NanoWiki - Brukerbidrag [nb]

TFY4340 - Mesoskopisk fysikk

2011-02-08T13:08:30Z

Audunnys:

{{Infobox
|Fakta vår 2011
|*Foreleser: Jon Andreas Støvneng
*Vurderingsform: Skriftlig eksamen
*Eksamensdato: 10. juni
}}

{{Infobox
|Øvingsopplegg vår 2011
|* Antall godkjente: ??/??
* Innleveringssted: ???
* Frist: ???
}}

Mesoskopisk fysikk (mesos (gr): mellom) foregår på en lengdeskala der både partikkel- og bølgeegenskapene til elektronene er viktig, typisk fra ti til noen hundre nanometer, dvs mellom det makroskopiske og det mikroskopiske atomære nivå. Moderne nanoteknologi har gjort det mulig å lage elektroniske kretser på en slik lengdeskala og dermed banet veien for oppdagelsen av en rekke nye fysiske effekter. Dette kurset vil ta for seg noen av de mest sentrale eksperimentelle resultatene gjennom de siste to-tre tiårene, der både klassisk fysikk og kvantemekanikk benyttes for å beskrive og forstå de ulike eksperimentene. Aktuelle tema er bl.a: kvantisert konduktans, Coulomb-blokkade, Büttiker-Landauer-formalisme, universelle konduktansfluktuasjoner, kvante-Hall-effekt, Aharonov-Bohm-effekt, gigantisk magnetoresistans.

== Eksterne linker ==

*[http://www.ntnu.no/studier/emner/TFY4340/2010 NTNUs fagbeskrivelse]
*[http://www.ntnu.no/studieinformasjon/timeplan/v11/?emnekode=TFY4340-1&valg=emnekode&bokst= Timeplan Vår11]

[[Kategori:Valgbare emner]]
[[Kategori:Fag 8. semester]]
[[Kategori:Fag]]

TFE4230 - Nanofotonikk

2011-01-24T13:20:00Z

Audunnys: /* Eksterne linker */

{{Infobox
|Fakta vår 2011
|*Foreleser: Helge Weman
*Vurderingsform: Skriftlig eksamen
*Eksamensdato: 21. mai
}}

{{Infobox
|Øvingsopplegg vår 2011
|* Antall godkjente: ??/??
* Innleveringssted: ???
* Frist: ???
}}

Kurset fokuserer på komponentutvikling og generelle konsepter innen de raskt ekspanderende feltene nanooptikk og nanofotonikk. Emner som dekkes inkluderer: nanoskala og nærfelts optikk, optiske nærfelts prober, kvantematerialer og plasmonikk. Nanofotoniske komponenter som diskuteres inkluderer: fotoniske krystaller, nanolasere, enkeltfotonkilder, nanostrukturerte solceller og sensorer.

== Eksterne linker ==

*[http://www.ntnu.no/studier/emner/TFE4230/2010 NTNUs fagbeskrivelse]
*[http://www.ntnu.no/studieinformasjon/timeplan/v11/?emnekode=TFE4230-1 Timeplan Vår11]

[[Kategori:Valgbare emner]]
[[Kategori:Fag 8. semester]]
[[Kategori:Fag]]

TFE4165 - Anvendt fotonikk

2011-01-24T13:19:42Z

Audunnys:

{{Infobox
|Fakta vår 2011
|*Foreleser: Dag Roar Hjelme
*Vurderingsform: Skriftlig eksamen
*Eksamensdato: 28. mai
*Pensum: E.A. Saleh, M.C. Teich: Fundamentals of Photonics
}}

{{Infobox
|Øvingsopplegg vår 2011
|* Antall godkjente: ??/??
* Innleveringssted: ???
* Frist: ???
}}

{{Infobox
|Lab vår 2010
|* Info om lab
}}

Optiske bølgeledere, integrert optikk og optiske fibre. Elektrooptikk, ikke-lineær optikk og akustooptikk. Spredning. Bølgeleder komponenter, optiske modulatorer og svitsjer. Fotodetektorer. Anvendelser av fotonikk innen optisk kommunikasjon, fiberoptiske sensorer og måleteknikk.

== Lab ==

== Eksterne linker ==

*[http://www.ntnu.no/studier/emner/TFE4165/2010 NTNUs fagbeskrivelse]
*[http://www.ntnu.no/studieinformasjon/timeplan/v11/?emnekode=TFE4165-1 Timeplan Vår11]

[[Kategori:Fag 8. semester]]
[[Kategori:Fag]]
[[Kategori:Valgbare emner]]

TFE4230 - Nanofotonikk

2011-01-24T13:16:29Z

Audunnys:

{{Infobox
|Fakta vår 2011
|*Foreleser: Helge Weman
*Vurderingsform: Skriftlig eksamen
*Eksamensdato: 21. mai
}}

{{Infobox
|Øvingsopplegg vår 2011
|* Antall godkjente: ??/??
* Innleveringssted: ???
* Frist: ???
}}

Kurset fokuserer på komponentutvikling og generelle konsepter innen de raskt ekspanderende feltene nanooptikk og nanofotonikk. Emner som dekkes inkluderer: nanoskala og nærfelts optikk, optiske nærfelts prober, kvantematerialer og plasmonikk. Nanofotoniske komponenter som diskuteres inkluderer: fotoniske krystaller, nanolasere, enkeltfotonkilder, nanostrukturerte solceller og sensorer.

== Eksterne linker ==

*[http://www.ntnu.no/studier/emner/TFE4230/2010 NTNUs fagbeskrivelse]
*[http://www.ntnu.no/studieinformasjon/timeplan/v11/?emnekode=TFE4230-1 Timeplan Vår10]

[[Kategori:Valgbare emner]]
[[Kategori:Fag 8. semester]]
[[Kategori:Fag]]

CMOS

2010-10-13T12:11:12Z

Audunnys: /* Fabrikasjon av en CMOS */

CMOS (Complementary metal oxide semiconductor) er en klasse av mange forskjellige integrerte kretser. CMOS brukes blant annet i mikroprosessorer.

== Fabrikasjon av en CMOS ==

Denne artikkelen er under arbeid. Det er lov å hjelpe til, og det er lov å pirke. For her går det litt fort i svingene.

I faget Halvlederteknologi lærer man hvordan en CMOS fabrikeres. Prosessen kan deles inn i 14 godt gjennomtenkte trinn.

'''1. Twin well process'''

Utgangspunktet for prosesseringen er en wafer av silisium. Se figuren under. Epilaget er av samme art som substratet, men renere og har færre defekter. Silisiumet er på forhånd dopet.

[[Bilde:Wafer.JPG|thumb|Wafer som anommer CMOS-fabrikken]]

Denne renses, renhet er uhyre viktig. Partikler, uorganiske og organiske forurensninger og oksidlag som skapes naturlig når silisiumet kommer i kontakt med oksygen ønskes fjernet. Deretter gror man med vilje et nytt oksidlag (temperatur rundt 1000 grader Celsius og tilførsel av Oksygen). Dette laget beskytter waferen mot nye forurensninger og forindrer at det blir stor skade på wafer ved kommende [[ioneimplantasjon]]. Det skal også bli lettere å kontrollere dybden ionene implanteres i. For ordens skyld er laget 150 Å tykt.

Ved [[Fotolitografi]] lages en maske med åpning der det skal lages i brønner, i første omgang for n-brønner. Seinere gjøres samme prosess for p-brønnene. N-brønnene og p-brønnene er de dopede områdene mellom source og drain i transistoren, hvorpå dopingen er av motsatt art enn den i source og drain. Fra nå av brukes det engelse ordet for brønn - well.

[[Bilde:Twinwell.JPG|thumb|Dannelsen av en n-dopet well (brønn)]]

p+ og p- angir henholdsvis tyngre og lett doping. Etter ioneimplatasjonen strippes fotoresisten med oksygen, og man renser waferen. Så varmebehandles waferen slik at dopingatomene aktiveres og eventuelle ødeleggelser av silisiumkrystallet helbredes. Dette står bedre begrunnet i artikkelen om [[ioneimplantasjon]].

Alt dette gjøres en gang til, men nå lages en p-well.

[[Bilde:Twinwell2.JPG|thumb|Nissens hjelpere står på. Her ser du dannelsen av en p-dopet well (brønn). Kanskje blir det hard pakke til jul?]]

'''2. Shallow trench isolation process'''

Nå ønsker man å lage isolerende områder mellom p- og n-wells. Dette er en prosess som krever mange steg. Foreløpig gidder jeg bare å gi en kort oppsummering:

2.1 Oksidlaget fra (1) fjernes, og nytt lages på samme måte.

2.2 Et lag med nitrid deposteres ved LPCVD (Low Pressure [[Chemical Vapour Deposition]]). Nitridlaget har til felles med oksidlag at det fungerer som maske, men siden nitridlaget er mye hardere fungerer det også som poleringsstopp - noe som kommer til nytte senere.

2.3 Ny runde med fotolitografi for å lage en maske for etsing.

2.4 Gropene som skal fylles med isolerende oksid etses. [[Etsing]]en skal være anisotrop.

2.5 Oksidlag dannes på veggene i gropa.

2.6 Oksid deponeres på wafer ved CVD.

2.7 Kjemisk-Mekanisk polering av oksidlaget. Poleringen stopper når man når nitridlaget.

2.8 Nitridlaget etses bort.

'''3. Poly gate structure process'''

Gaten lages av polysilisium, fra nå av kalt poly. Poly deponeres på wafer, og maske lages. Poly etses bort, bortsett fra der gaten er.

'''4. Lightly doped drain'''

Source og drain dopes i to omganger. Først en lett og grunn doping, deretter en sterkere og litt dypere doping. I denne omgangen gjøres den lette dopingen.

Man bruker fotolitografi for å lage en maske som beskytter n-well når man skal dope source og drain til p-well. Source og drain til p-well skal nemlig n-dopes, og man ønsker for all del ikke å øke dopingkonsentrasjonen i n-well. Motsatt i tilfellet for doping av source og drain til n-well.

Dopingen skjer med tyngre dopingmidler for at dopingen ikke skal trenge for dypt ned. Arsenikk (As) of BF<sub>2</sub> brukes som henholdsvis n- og p-doping.

'''5. Sidewall spacer formation'''

Før man kommer med den tyngre dopingen i source og drain, ønsker man å beskytte sideveggene til gate, slik at ioner ikke hopper inn der. Et oksidlag deponeres, og etses bort (dry plasma etch). Det flotte er at når man etser på denne måten (anisotropt) blir oksidet på sideveggene til gate igjen.

'''6. Source/Drain implant'''

På lignede måte som i (4) dopes source og drain. Denne gangen implanteres dopingatomne litt dypere.

'''7. Contact formation'''

Man ønsker å lage kontakter på de aktive områdene (source, drain, gate). Titan brukes. Titan binder seg godt til silisium, men ikke silisiumoksid. Derfor kan man deponere Titan på waferen, og etse. Kun titanet som ligger oppå oksider forsvinner. Det er tøffe krav til kontaktenes egenskaper; ... her er det noen krav. Kommer senere.

'''8. Local Interconnect Process (LI)'''
[[Bilde:Cmosmanufacturingsteps.JPG|thumb|Alle stegene i prossessruten for CMOS IC.]]
Neste steg på vegen er å lage tilkoblinger mellom kontaktene du lagde i trinn 7. Man begynne med å deponere et nitridlag (Silisiumnitrid) på waferen. Dette laget skal beskytte aktive områder mot dopingen i det kommende oksidlaget. For oppå nitridlaget deponeres et oksidlag som skal virke isolerende mellom silisiumen og metallaget som kommer senere. Ved å dope oksidet forbedres de dielektriske egenskapene til oksidet. Oksidet varmes slikt at det flyter utover, flaten blir litt rettere. Nå poleres oksidet slik at laget blir helt plant. Det er viktig for å få best mulig resultat i neste steg som er fotolitografi. En maske lages, og man etser ut groper der man ønsker tilkoblinger. Som over source og drain.

Nå skal man fylle disse hullene med noe som gir elektrisk kontakt. Først et lag med Titan, som forbedrer adhesjonen mellom lagene. Så et lag med TiN, som virker som en diffusjonsbarriere mellom Wolfram (tungsten) og oksidet. Det er nemlig Wolfram som brukes til å fylle kontaktene. Dette materialet fyller hull godt. Det er viktig å unngå tomrom, samt at det har gode "poleringsegenskaper", og leder strøm.

Når alt dete er deponert er det selvfølgelig et lag av litt av hvert oppå oksidet (interlayer dielectric, ILD). Dette laget med litt av hvert poleres bort.

'''9. Via-1 og Plug-1 formasjon'''

Ny oksiddeponering, polering og fotolitografi for å etse hull til viasene. Deponering av Ti og TiN av samme grunner som tidligere. Viasene fylles med Wolfram, og polering. Alle disse prosesstegene er av samme årsak som i punkt 8.

'''10. Metal-1 Interconnect formasjon'''

Titanlag deponeres for god adhesjon mellom metall og W-pluggene. Ledningsmetallet deponeres så (i dette eksempelet er det Aluminium blandet med 1 % Cu . Dette er ikke tilfeldig. Det er en grunn, men den har jeg glemt. På toppen av metallet legges et lag TiN, som er et anti refleksjonslag som kommer til nytte når man IGJEN skal kjøre fotolitografi og lage maske til etsing av steder man ikke ønsker metall. (Da etses alle tre lagene - Ti, Al, TiN - bort akkurat der.

'''11. - 12. Nye vias og metalllag '''

Her gjøres ca samme prosedyre som 9. og 10. så mange ganger som trengs, for å skape de tilkoplingsmulighetene som er ønsket.

'''13. Topplag'''

Når alle lagene med vias og metall er lagd, lager man et likeens metallag på toppen, og et isolerende lag, og et lag med "bonding pad metal, evt nytt dielektrisk lag, og et passiveringslag på toppen som skal beskytte CMOS mot mekanisk skade.

''' 14. Testing'''

Så er det igjen å teste om alt er som det skal.

Millimeter

2010-10-13T12:09:48Z

Audunnys: Ny side: En millimeter (mm) er <math>10^6</math> nanometer (nm).

En millimeter (mm) er <math>10^6</math> [[nanometer]] (nm).

Fagoversikt

2010-09-06T12:00:11Z

Audunnys: /* Emner utenom fagplanen */

For Studiehåndbok for teknologistudiet (sivilingeniør) ved NTNU 2009-2010 se [http://www.ntnu.no/studier/studiehandbok/teknologi her]. Denne inneholder overgangsordninger for 3. klasse i 2009/2010.

== Felles obligatoriske emner i fagplanen ==

=== 1. klasse ===

{| class="wikitable sortable"
|-
! Fagkode
! Emnetittel
! Semester
! Studiepoeng
|-
| [[TDT4105]]
| Informasjonsteknologi, GK
| 1. Høst
| 7,5
|-
| [[TFE4220]]
| Nanoteknologi intro
| 1. Høst
| 7,5
|-
| [[TMA4100]]
| Matematikk 1
| 1. Høst
| 7,5
|-
| [[TFY4115]]
| Fysikk
| 1. Høst
| 7,5
|-
| [[TMA4105]]
| Matematikk 2
| 2. Vår
| 7,5
|-
| [[TMA4115]]
| Matematikk 3
| 2. Vår
| 7,5
|-
| [[TMT4110]]
| Kjemi
| 2. Vår
| 7,5
|-
| [[EXPH0001]]
| Filosofi og vitenskapsteori
| 2. Vår
| 7,5
|-
|}

=== 2. klasse ===

{| class="wikitable sortable"
|-
! Fagkode
! Emnetittel
! Semester
! Studiepoeng
|-
| [[TBT4160]]
| Organisk kjemi og biokjemi (1)
| 3. Høst
| 7,5
|-
| [[TFE4180]]
| Halvlederteknologi
| 3. Høst
| 7,5
|-
| [[TMT4185]]
| Materialteknologi
| 3. Høst
| 7,5
|-
| [[TMA4130]]
| Matematikk 4N
| 3. Høst
| 7,5
|-
| [[TFE4120]]
| Elektromagnetisme
| 4. Vår
| 7,5
|-
| [[TKP4115]]
| Overflate- og kolloidkjemi (2)
| 4. Vår
| 7,5
|-
| [[TKJ4215]]
| Statistisk termodynamikk i kjemi og biologi
| 4. Vår
| 7,5
|-
| [[TMA4245]]
| Statistikk
| 4. Vår
| 7,5
|-
|}
Fra studieåret 2010/2011:

(1) Splittes til to fag Organisk kjemi GK og Bioteknologi GK.

(2) Byttes ut med Bioteknologi GK, gjøres obligatorisk for NanoMEM og valgbart for Bionano og Nanoelektronikk i 3. klasse.

=== 3. klasse ===

{| class="wikitable sortable"
|-
! Fagkode
! Emnetittel
! Semester
! Studiepoeng
|-
| [[TFY4170]]
| Fysikk 2
| 5. Høst
| 7,5
|-
| [[TFY4335]]
| Bionanovitenskap
| 5. Høst
| 7,5
|-
| [[TFY4185]]
| Måleteknikk
| 5. Høst
| 7,5
|-
| [[TMT4320]]
| Nanomaterialer
| 5. Høst
| 7,5
|-
| [[TFY4220]]
| Faste stoffers fysikk (erstatter TFE4215, er like)
| 6. Vår
| 7,5
|-
| [[TIØ4257]]
| Teknologiledelse
| 6. Vår
| 7,5
|-
|}

=== 4. klasse ===

{| class="wikitable sortable"
|-
! Fagkode
! Emnetittel
! Semester
! Studiepoeng
|-
|
| Perspektivemne
| 7. Høst
| 7,5
|-
| [[Eksperter i team]]
| Eksperter i team
| 8. Vår
| 7,5
|-
| [[TFY4330]]
| Nanoverktøy (Revideres)
| 8. Vår
| 7,5
|-
|}

=== 5. klasse ===

{| class="wikitable sortable"
|-
! Fagkode
! Emnetittel
! Semester
! Studiepoeng
|-
|
| Ikke-teknologisk emne
| 9. Høst
| 7,5
|-
|
| Fordypningsemne
| 9. Høst
| 7,5
|-
|
| Fordypningsproskjekt
| 9. Høst
| 15
|-
|
| Masteroppgave
| 10. Vår
| 30
|-
|}

==Emner for retning Bionano ==

=== 3. klasse ===

{| class="wikitable sortable"
|-
! Fagkode
! Emnetittel
! Semester
! Merknad
! Studiepoeng
|-
| [[TKP4115]]
| Overflate- og kolloidkjemi
| 6. Vår
|
| 7,5
|-
| [[TBT4110]]
| Mikrobiologi
| 6. Vår
|
| 7,5
|-
| [[TFY4195]]
| Optikk
| 6. Vår
|
| 7,5
|-
| [[TFY4260]]
| Cellbiologi og cellulær biofysikk
| 6. Vår
| Anbefalt
| 7,5
|-
| [[TMM4100]]
| Materialteknikk I
| 6. Vår
|
| 7,5
|-
| [[TMM4175]]
| Polymerer og kompositter
| 6. Vår
|
| 7,5
|-
|}

=== 4. klasse ===

{| class="wikitable sortable"
|-
! Fagkode
! Emnetittel
! Semester
! Merknad
! Studiepoeng
|-
| [[MOL3014]]
| Nanomedisin I - Bioanalyse
| 7. Høst
| Obligatorisk
| 7,5
|-
| [[MOL3005]]
| Immunologi
| 7. Høst
|
| 7,5
|-
| [[TBT4102]]
| Biokjemi 1
| 7. Høst
|
| 7,5
|-
| [[TBT4135]]
| Biopolymerkjemi
| 7. Høst
| (1)
| 7,5
|-
| [[TFY4265]]
| Biofysiske mikroteknikker
| 7. Høst
| Anbefalt
| 7,5
|-
| [[TFE4160]]
| Elektrooptikk og lasere
| 7. Høst
|
| 7,5
|-
| [[MOL3015]]
| Nanomedisin II - Terapi
| 8. Vår
| Obligatorisk
| 7,5
|-
| [[MOL3007]]
| Funksjonell genomforskning
| 8. Vår
|
| 7,5
|-
| [[TFY4195]]
| Optikk
| 8. Vår
|
| 7,5
|-
| [[TOKS3001]]
| Medisinsk toksikologi
| 8. Vår
|
| 7,5
|-
| [[TBT4110]]
| Mikrobiologi
| 8. Vår
|
| 7,5
|-
| [[TEP4100]]
| Fluidmekanikk
| 8. Vår
|
| 7,5
|-
|}

(1) Anbefalt emne for studenter som planlegger fordypningsprosjekt eller master ved Institutt for bioteknologi.

==Emner for retning Nanomaterialer ==

=== 3. klasse ===

{| class="wikitable sortable"
|-
! Fagkode
! Emnetittel
! Semester
! Merknad
! Studiepoeng
|-
| [[TKP4115]]
| Overflate- og kolloidkjemi
| 6. Vår
| Obligatorisk
| 7,5
|-
| [[TKP4190]]
| Fabrikasjon og anvendelse av nanomaterialer
| 6. Vår
| (1)
| 7,5
|-
| [[TFY4195]]
| Optikk
| 6. Vår
|
| 7,5
|-
| [[TKJ4166]]
| Kjemisk bindingsteori og spektroskopi
| 6. Vår
|
| 7,5
|-
| [[TKP4130]]
| Polymerkjemi
| 6. Vår
|
| 7,5
|-
| [[TMT4285]]
| Hydrogenteknologi, brenselceller og solceller
| 6. Vår
|
| 7,5
|-
| [[TDT4100]]
| Objektorientert programmering
| 6. Vår
|
| 7,5
|-
|}

(1) Obligatorisk, emnet må velges i 3. eller 4. årskurs.

=== 4. klasse ===

{| class="wikitable sortable"
|-
! Fagkode
! Emnetittel
! Semester
! Merknad
! Studiepoeng
|-
| [[TFY4255]]
| Materialfysikk
| 7. Høst
|
| 7,5
|-
| [[TFE4145]]
| Elektronfysikk
| 7. Høst
|
| 7,5
|-
| [[TFY4300]]
| Energi og miljøfysikk
| 7. Høst
|
| 7,5
|-
| [[TKP4155]]
| Reaksjonskinetikk og katalyse
| 7. Høst
|
| 7,5
|-
| [[TMT4145]]
| Keramisk material vitenskap
| 7. Høst
|
| 7,5
|-
| [[TFY4250]]
| Atom- og molekylfysikk
| 7. Høst
|
| 7,5
|-
| [[TMT4155]]
| Heterogene likevekter og fasediagram
| 7. Høst
|
| 7,5
|-
| [[TFE4160]]
| Elektrooptikk og lasere
| 7. Høst
| (1)
| 7,5
|-
| [[TKJ4205]]
| Molekylmodellering
| 7. Høst
| (1)
| 7,5
|-
| [[TMT4222]]
| Metallenes mekaniske egenskaper
| 7. Høst
| (1)
| 7,5
|-
| [[TMT4322]]
| Solceller og fotovoltaiske nanostrukturer
| 8. Vår
|
| 7,5
|-
| [[TMT4245]]
| Funksjonelle materialer
| 8. Vår
|
| 7,5
|-
| [[TFY4200]]
| Optikk, videregående kurs
| 8. Vår
|
| 7,5
|-
| [[TFE4230]]
| Nanofotonikk
| 8. Vår
|
| 7,5
|-
| [[TEP4220]]
| Energi og miljøkonsekvensanalyse
| 8. Vår
|
| 7,5
|-
| [[TFY4245]]
| Faststoff-fysikk, videregående kurs
| 8. Vår
|
| 7,5
|-
| [[TKP4190]]
| Fabrikasjon og anvendelse av nanomaterialer
| 8. Vår
| (2)
| 7,5
|-
| [[TFE4210]]
| Nanoelektronikk
| 8. Vår
| (1)
| 7,5
|-
| [[TKP4130]]
| Polymerkjemi
| 8. Vår
| (1), Gjelder kun 2009/2010
| 7,5
|-
|}

(1) Ikke hensyn ved time- og eksamensplanlegging.

(2) Obligatorisk, emnet må velges i 3. eller 4. årskurs.

==Emner for retning Nanoelektronikk ==

=== 3. klasse ===

{| class="wikitable sortable"
|-
! Fagkode
! Emnetittel
! Semester
! Merknad
! Studiepoeng
|-
| [[TFY4195]]
| Optikk
| 6. Vår
| Anbefalt
| 7,5
|-
| [[TDT4100]]
| Objektorientert programmering
| 6. Vår
|
| 7,5
|-
| [[TDT4102]]
| Prosedyre- og objektorientert programmering
| 6. Vår
|
| 7,5
|-
| [[TFY4215]]
| Kjemisk fysikk/kvantemekanikk
| 6. Vår
|
| 7,5
|-
| [[TFY4235]]
| Numerisk fysikk
| 6. Vår
|
| 7,5
|-
| [[TKP4115]]
| Overflate og kolloidkjemi
| 6. Vår
|
| 7,5
|-
|}

=== 4. klasse ===

{| class="wikitable sortable"
|-
! Fagkode
! Emnetittel
! Semester
! Merknad
! Studiepoeng
|-
| [[TFY4250]]
| Atom- og molekylfysikk
| 7. Høst
|
| 7,5
|-
| [[FY3114]]
| Funksjonelle materialer
| 7. Høst
|
| 7,5
|-
| [[TFE4145]]
| Elektronfysikk
| 7. Høst
| Anbefalt
| 7,5
|-
| [[TFE4160]]
| Elektrooptikk og lasere
| 7. Høst
|
| 7,5
|-
| [[TFE4225]]
| MEMS-design
| 7. Høst
|
| 7,5
|-
| [[TFY4205]]
| Kvantemekanikk
| 7. Høst
|
| 7,5
|-
| [[TFE4230]]
| Nanofotonikk
| 8. Vår
|
| 7,5
|-
| [[TFY4340]]
| Mesoskopisk fysikk
| 8. Vår
|
| 7,5
|-
| [[TFE4165]]
| Anvendt fotonikk
| 8. Vår
|
| 7,5
|-
| [[TFE4210]]
| Nanoelektronikk
| 8. Vår
| Anbefalt
| 7,5
|-
| [[TFY4210]]
| Anvendt kvantemekanikk
| 8. Vår
|
| 7,5
|-
| [[TFY4245]]
| Faststoff-fysikk, videregående kurs
| 8. Vår
|
| 7,5
|-
|}

==Emner utenom fagplanen==

{| class="wikitable sortable"
|-
! Fagkode
! Emnetittel
! Studiepoeng
|-
| [[NEVR2010]]
| Innføring i nevrovitenskap
| 15
|-
| [[NEVR2020]]
| Innføring i nevrovitenskap
| 7,5
|-
| [[MFEL1010]]
| Innføring i medisin for ikke-medisinere
| 7,5
|-
| [[TTT4234]]
| Romteknologi I
| 7,5
|-
| [[TTT4235]]
| Romteknologi II
| 7,5
|-
|}

==Eldre fagplaner==
*[[Emner i fagplanen 2009/2010]]
*[[Emner i fagplanen 2008/2009]]

Fil:Img 0725.jpg

2010-05-14T15:17:31Z

Audunnys: test

test

TKJ4215 - Statistisk termodynamikk i kjemi og biologi

2009-08-18T09:42:21Z

Audunnys:

{{Infobox
|Statistisk termodynamikk i kjemi og biologi
|*Faglærer: Øystein Hestad
*Stud.ass.: Audun Nystad Bugge
*Vurderingsform: Skriftlig eksamen
*Eksamensdato: 8/12 2009
}}

{{Infobox
|Øvingsopplegg høst 2008
|* 2x2 timer i uken med frivillige øvinger
}}

Statistisk termodynamikk (også kjent som statistisk mekanikk) tar som mål å forklare mye av termodynamikken ut fra statistiske grunnprinsipp. Fra våren 2010 vil statistisk termodynamikk bli undervist i 4. semester.

== Faglig ==
=== Statistikk ===
Dersom <math>N</math> objekter skal ordnes blir antall mulige ordninger <math>N!</math> dersom partiklene er distinkte, altså at de kan skilles fra hverandre, eller <math>\frac{N!}{n_1!\cdot n_2!\cdot ... \cdot n_i!}</math>, dersom hver av de <math>n_i</math> kategoriene er distinkt fra de andre <math>n_{i-1}</math> kategoriene, men objektene i hver kategori ikke er distinkte.

For ''n'' ikke distinkte partikler som kan fordeles i ''N'' tilstander blir antall mulige konfigurasjoner da <math>\frac{N!}{n!\cdot (N-n)!}</math>

=== Ensembler ===
Hvordan skal man vite hvilke variabler som er frie og hvilke som er avhengig for en gitt termodynamisk funksjon? Med hvilke forbehold er variabler definert? Svaret ligger i hvilke ensembler som brukes.

Termodynamiske variabler kommer i to hovedvarianter: ekstensive og intensive. De ekstensive variablene er lik summen av variablene for delsystemer, f.eks. er volumet til et system satt sammen av delsystemer A og B lik volumet av A pluss volumet av B. Dette er ikke tilfellet for f.eks. temperatur, som er en intensiv variabel.

Det er to ensembler som defineres kun ut i fra de ekstensive variablene: <math>U(S,V,N)</math> og <math>S(U,V,N)</math>. Disse ensemblene (altså (S,V,N) og (U,V,N) ensamblene) definerer enkle termodynamiske system fullstendig, og differensialformene av disse angir alle endringer som kan skje i systemene. Dette gjør også F(T,V,N), H(S,p,N) og G(T,p,N), men disse inneholder kombinasjoner av intensive og ekstensive variabler.

Termodynamikken er definert ut i fra den indre energien, der det er entropien S, volumet V og antall partikler N som er de frie variablene. Denne kan defineres på differensialform:

<math>dU=\left(\frac{\partial U}{\partial S}\right)_{V,N} dS+\left(\frac{\partial U}{\partial V}\right)_{S,N}dV+\left(\frac{\partial U}{\partial N_j}\right)_{S,V} dN_j</math>

Legg merke til to ting her: det ene er at ingen relasjoner har blitt definert, man har kun sagt at den indre energien er en funksjon av kun ekstensive variabler, og at den dermed er homogen (se [http://en.wikipedia.org/wiki/Homogeneous_function]). Derfor må de andre ensemblene (bortsett fra S(U,V,N)) defineres ut i fra denne. Det andre som er viktig er at det blir gjort [http://en.wikipedia.org/wiki/Partial_differential partielle derivasjoner], der man deriverer med hensyn på en variabler og holder de andre som konstante. Dermed kan vi definere de intensive variablene slik:

<math>T=\left(\frac{\partial U}{\partial S}\right)_{V,N}, p = -\left(\frac{\partial U}{\partial V}\right)_{S,N},\mu_j = \left(\frac{\partial U}{\partial N_j}\right)_{S,V} . </math>

Legg merke til betingelsene for at hver skal gjelde. Ved bruk av Maxwell-relasjoner vil disse betingelsene endre seg grunnet partiell derivasjon med hensyn på andre variabler, men tankegangen er den samme.

==Notater fra Boka==
'''Dette er tilpassa fra notatene som Dag Håkon la ut på forumet.'''
===Kapittel 1: Prinsipper i sannsynlighet===
Dette kapittelet er en innføring i enkel sannsynlighetsregning som brukes når man regner på
entropi på mikronivå.

Definisjonen av sannsynlighet: <math> p_A = \left(\frac{n_A}{N}\right)</math>

Antallet måter man kan velge ut n av N på: <math>W(n,N) = \frac{N!}{n! (N-n)!}</math>

dette kalles også multiplisiteten i termodynamikken.

Videre går kapittelet gjennom sannsylighetsregning som forventes å kunne fra [[TMA4245]].

===Kapittel 2: Bunn- og toppunktsanalyse – forutsi likevekt ===
For å minimere eller maksimere en variabel i en termodynamisk funksjon bruker man ofte
derivasjon. Dette eksemplifiseres i dette kapitlet.

===Kapittel 3: Varme, arbeid og energi ===
”Varme strømmer mot å maksimere entropien”

Kinetisk energi til et legeme med fart v og masse m: <math>K = \frac{1}{2}mv^2</math>

Loven om konservering av energi: <math> E_{kin} + E_{pot} = E_{tot} = konstant </math>

Termisk vs. kinetisk energi for et gassmolekyl: <math>\frac{3}{2}k_B T = \frac{m\langle v^2\rangle}{2}</math>

===Kapittel 4: Matematiske verktøy: Rekker og tilnærminger===
Mange av konvergensene for rekker finner man i Rottmann, og forklaring på Taylor-rekker
finnes på side 53 i boka. I dette faget kan ofte Stirlings approksimasjon være nyttig:

<math>n! = \sqrt{2\pi n}\left(\frac{n}{e}\right)^n</math>

Det er en konvensjon at når ''n'' er større enn 10, kan Stirlings formel forenkles til:

<math>n!=\left (\frac{n}{e} \right )^n</math>

Det er denne formen som brukes i alle forenklingene senere i kapitlene, da ''n'' i alle reelle system vil være veldig mye høyere enn 10.

===Kapittel 5: Matematiske verktøy: Flervariabel kalkulus===
For at en punkt skal være et ektrempunkt i en flervariabel funksjon, må alle partiellderiverte
være lik 0.

Ofte er det i tillegg til funksjonen vi skal regne på en betingelsesfunksjon, for å regne med
dette er Lagranges multiplikatormetode nyttig:

<math>\left(\frac{\partial f}{\partial x}\right)_y = \lambda \left(\frac{\partial g}{\partial x}\right)_y</math> , <math>\left(\frac{\partial f}{\partial y}\right)_x = \lambda \left(\frac{\partial g}{\partial y}\right)_x</math>

Eulers resiproke sammenheng: <math>\left(\frac{\partial^2 f}{\partial x \partial y}\right) = \left(\frac{\partial^2 f}{\partial y \partial x}\right)</math>

Kjerneregel og partiellderivasjon forventes å kunne fra [[TMA4105]].

===Kapittel 6: Entropi og Boltzmann-loven===
<math>S = k_B \ln{W}</math>

hvor W er multiplisiteten.

Når man regner med multiplisiteter kan det lønne seg å bruke Stirlings approksimasjon.

Entropi er såkalt uorden i systemet, som er proporsjonal med antallet tilstander systemet kan
være i. Å regne på entropi kan sammenliknes med å regne på sannsynligheter. For å regne å
entropiendringer bruker man Boltzmanns distribusjonslov: <math>p_i^* = \frac{e^{-\beta \epsilon_i}}{\sum_{i=1}^t e^{-\beta \epsilon_i}} = \frac{e^{-\beta \epsilon_i}}{q}</math>

Hvor q er partisjonsfunskjonen, som er summen av alle tilstander tilgjengelig for systemet under de gitte forutsetninger.

<math>q = \sum_{i=1}^t e^{-\beta \epsilon_i}</math>

===Kapittel 7: Termodynamiske drivkrefter===
I termodynamikken snakker man ofte om termodyamiske systemer, disse er definert som ulike typer listet opp på side 106 i boka.

Variabler i et system kan deles i intensive og ekstensive. En intensiv variabel er uavhengige av størrelsen på systemet, for eksempel temperatur. Temperaturen dobles IKKE når to like varme legoklosser settes sammen. En ekstensiv variabel er avhengig av størrelsen på systemet, for eksempel er antallet molekyler i to legoklosser satt sammen lik summen av molekylene i de to klossene.

Den fundamentale termodynamiske likingen for energi: <math>U = U\left(S,V,N\right)</math>

Såkalte fundamentallikinger kan skrives på derivatform, som for eksempel:

<math>dU = TdS - pdV + \sum_{j=1}^M \mu_j dN_j</math>

Ved å gjøre om på derivatformer og vet å bruke definisjoner på variabler kan man komme fram til andre fundamentallikninger på diffrensialform, for eksempel for entropi:

<math>dS = \left(\frac{1}{T}\right)dU + \left(\frac{p}{T}\right)dV - \sum_{j=1}^M \left(\frac{\mu_j}{T}\right) dN_j</math>

Ved å se på de matematiske definisjonene på temperatur, trykk og kjemisk potensial kan man si:
* 1/T gir tendensen til varmestrøm
* p/T gir tendensen for volumendring
* μ/T gir tendensen for utveksling av stoff
For at et system skal være i likevekt må dS=0 være oppfylt.
En kvasi-statisk prosess er en prosess som er så treg at verken tid eller hastighet spiller noen rolle. I en slik prosess er arbeidet utført ved konstant trykk og en volumendring fra Vi til Vf gitt ved:

<math>w = -\int_{V_a}^{V_b} p_{ext} dV = -p_{ext}\left(V_B - V_A\right)</math>

Termodynamikkens første lov; Endring i energi er summen av varme tilført og arbeid utført på systemet: <math>dU = \partial q + \partial w</math>

For kvasi-statiske prosesser gjelder også: <math>\partial w = -pdV</math>, <math>dS = \frac{\partial q}{T}</math>

Den siste likningen kalles ofte den termodynamiske definisjonen på entropi.

===Kapittel 8: Laboratoriebetingelser og frie energier===
2 hovedtyper fri energi:
* Helmholtz fri energi: F = U - TS
* Gibbs fri energi: G = H - TS

Akkurat som maksimering av entropien er en betingelse for likevekt, er også minimalisering av fri energi det.

H er entalpi som er summen av indre egergi og volum/trykk-arbeid:
<math>H = H\left(S, p, N\right) = U + pV dH = dU + pdV + Vdp</math>

Her følger en oversikt over fundamentale funskjoner hva likevekt angår:

{| class="wikitable"
|-
! Funksjon
! Ved likevekt
! Fundamental likning
! Definisjon
|-
| U(S,V,N)
| min
| <math>dU = TdS - pdV + \sum_j \left(\mu_j dN_j\right)</math>
|
|-
| S(U,V,N)
| maks
| <math>dS = \left(\frac{1}{T}\right)dU + \left(\frac{p}{T}\right)dV - \sum_j \left(\frac{\mu_j}{T}\right) dN_j</math>
|
|-
| H(S,p,N)
| min
| <math>dH = TdS + VdP - \sum_j \left(\mu_j dN_j\right)</math>
| H = U + pV
|-
| F(T,V,N)
| min
| <math>dF = -SdT - pdV + \sum_j \left(\mu_j dN_j\right)</math>
| F = U - TS
|-
| G(T,p,N)
| min
| <math>dG = -SdT + Vdp + \sum_j \left(\mu_j dN_j\right)</math>
| G = H - TS
|-
|}

Varmekapasitet ved konstant volum:

<math>C_V = \left(\frac{\partial q}{\partial T}\right)_V = \left(\frac{\partial U}{\partial T}\right)_V = T \left(\frac{\partial S}{\partial T}\right)_V</math>

Varmekapasitet ved konstant trykk:

<math>C_p = \left(\frac{\partial q}{\partial T}\right)_p = \left(\frac{\partial H}{\partial T}\right)_p = T \left(\frac{\partial S}{\partial T}\right)_p</math>

== Eksterne linker ==

*[http://www.ntnu.no/studier/emner?emnekode=TKJ4215 NTNUs fagbeskrivelse]
*[http://www.ntnu.no/studieinformasjon/timeplan/h08/?emnekode=TKJ4215-1 Timeplan Høsten 08]

[[Kategori:Obligatoriske emner]]
[[Kategori:Fag 4. semester]]
[[Kategori:Fag 5. semester]]
[[Kategori:Fag]]

TKJ4215 - Statistisk termodynamikk i kjemi og biologi

2009-05-30T09:39:02Z

Audunnys: Endrer stud.ass

{{Infobox
|Statistisk termodynamikk i kjemi og biologi
|*Faglærer: Per-Olof Åstrand
*Stud.ass.: Audun Nystad Bugge
*Vurderingsform: Skriftlig eksamen
*Eksamensdato: ?
}}

{{Infobox
|Øvingsopplegg høst 2008
|* 2x2 timer i uken med frivillige øvinger
}}

Statistisk termodynamikk (også kjent som statistisk mekanikk) tar som mål å forklare mye av termodynamikken ut fra statistiske grunnprinsipp. Fra våren 2010 vil statistisk termodynamikk bli undervist i 4. semester.

== Faglig ==
=== Statistikk ===
Dersom <math>N</math> objekter skal ordnes blir antall mulige ordninger <math>N!</math> dersom partiklene er distinkte, altså at de kan skilles fra hverandre, eller <math>\frac{N!}{n_1!\cdot n_2!\cdot ... \cdot n_i!}</math>, dersom hver av de <math>n_i</math> kategoriene er distinkt fra de andre <math>n_{i-1}</math> kategoriene, men objektene i hver kategori ikke er distinkte.

For ''n'' ikke distinkte partikler som kan fordeles i ''N'' tilstander blir antall mulige konfigurasjoner da <math>\frac{N!}{n!\cdot (N-n)!}</math>

=== Ensembler ===
Hvordan skal man vite hvilke variabler som er frie og hvilke som er avhengig for en gitt termodynamisk funksjon? Med hvilke forbehold er variabler definert? Svaret ligger i hvilke ensembler som brukes.

Termodynamiske variabler kommer i to hovedvarianter: ekstensive og intensive. De ekstensive variablene er lik summen av variablene for delsystemer, f.eks. er volumet til et system satt sammen av delsystemer A og B lik volumet av A pluss volumet av B. Dette er ikke tilfellet for f.eks. temperatur, som er en intensiv variabel.

Det er to ensembler som defineres kun ut i fra de ekstensive variablene: <math>U(S,V,N)</math> og <math>S(U,V,N)</math>. Disse ensemblene (altså (S,V,N) og (U,V,N) ensamblene) definerer enkle termodynamiske system fullstendig, og differensialformene av disse angir alle endringer som kan skje i systemene. Dette gjør også F(T,V,N), H(S,p,N) og G(T,p,N), men disse inneholder kombinasjoner av intensive og ekstensive variabler.

Termodynamikken er definert ut i fra den indre energien, der det er entropien S, volumet V og antall partikler N som er de frie variablene. Denne kan defineres på differensialform:

<math>dU=\left(\frac{\partial U}{\partial S}\right)_{V,N} dS+\left(\frac{\partial U}{\partial V}\right)_{S,N}dV+\left(\frac{\partial U}{\partial N_j}\right)_{S,V} dN_j</math>

Legg merke til to ting her: det ene er at ingen relasjoner har blitt definert, man har kun sagt at den indre energien er en funksjon av kun ekstensive variabler, og at den dermed er homogen (se [http://en.wikipedia.org/wiki/Homogeneous_function]). Derfor må de andre ensemblene (bortsett fra S(U,V,N)) defineres ut i fra denne. Det andre som er viktig er at det blir gjort [http://en.wikipedia.org/wiki/Partial_differential partielle derivasjoner], der man deriverer med hensyn på en variabler og holder de andre som konstante. Dermed kan vi definere de intensive variablene slik:

<math>T=\left(\frac{\partial U}{\partial S}\right)_{V,N}, p = -\left(\frac{\partial U}{\partial V}\right)_{S,N},\mu_j = \left(\frac{\partial U}{\partial N_j}\right)_{S,V} . </math>

Legg merke til betingelsene for at hver skal gjelde. Ved bruk av Maxwell-relasjoner vil disse betingelsene endre seg grunnet partiell derivasjon med hensyn på andre variabler, men tankegangen er den samme.

==Notater fra Boka==
'''Dette er tilpassa fra notatene som Dag Håkon la ut på forumet.'''
===Kapittel 1: Prinsipper i sannsynlighet===
Dette kapittelet er en innføring i enkel sannsynlighetsregning som brukes når man regner på
entropi på mikronivå.

Definisjonen av sannsynlighet: <math> p_A = \left(\frac{n_A}{N}\right)</math>

Antallet måter man kan velge ut n av N på: <math>W(n,N) = \frac{N!}{n! (N-n)!}</math>

dette kalles også multiplisiteten i termodynamikken.

Videre går kapittelet gjennom sannsylighetsregning som forventes å kunne fra [[TMA4245]].

===Kapittel 2: Bunn- og toppunktsanalyse – forutsi likevekt ===
For å minimere eller maksimere en variabel i en termodynamisk funksjon bruker man ofte
derivasjon. Dette eksemplifiseres i dette kapitlet.

===Kapittel 3: Varme, arbeid og energi ===
”Varme strømmer mot å maksimere entropien”

Kinetisk energi til et legeme med fart v og masse m: <math>K = \frac{1}{2}mv^2</math>

Loven om konservering av energi: <math> E_{kin} + E_{pot} = E_{tot} = konstant </math>

Termisk vs. kinetisk energi for et gassmolekyl: <math>\frac{3}{2}k_B T = \frac{m\langle v^2\rangle}{2}</math>

===Kapittel 4: Matematiske verktøy: Rekker og tilnærminger===
Mange av konvergensene for rekker finner man i Rottmann, og forklaring på Taylor-rekker
finnes på side 53 i boka. I dette faget kan ofte Stirlings approksimasjon være nyttig:

<math>n! = \sqrt{2\pi n}\left(\frac{n}{e}\right)^n</math>

Det er en konvensjon at når ''n'' er større enn 10, kan Stirlings formel forenkles til:

<math>n!=\left (\frac{n}{e} \right )^n</math>

Det er denne formen som brukes i alle forenklingene senere i kapitlene, da ''n'' i alle reelle system vil være veldig mye høyere enn 10.

===Kapittel 5: Matematiske verktøy: Flervariabel kalkulus===
For at en punkt skal være et ektrempunkt i en flervariabel funksjon, må alle partiellderiverte
være lik 0.

Ofte er det i tillegg til funksjonen vi skal regne på en betingelsesfunksjon, for å regne med
dette er Lagranges multiplikatormetode nyttig:

<math>\left(\frac{\partial f}{\partial x}\right)_y = \lambda \left(\frac{\partial g}{\partial x}\right)_y</math> , <math>\left(\frac{\partial f}{\partial y}\right)_x = \lambda \left(\frac{\partial g}{\partial y}\right)_x</math>

Eulers resiproke sammenheng: <math>\left(\frac{\partial^2 f}{\partial x \partial y}\right) = \left(\frac{\partial^2 f}{\partial y \partial x}\right)</math>

Kjerneregel og partiellderivasjon forventes å kunne fra [[TMA4105]].

===Kapittel 6: Entropi og Boltzmann-loven===
<math>S = k_B \ln{W}</math>

hvor W er multiplisiteten.

Når man regner med multiplisiteter kan det lønne seg å bruke Stirlings approksimasjon.

Entropi er såkalt uorden i systemet, som er proporsjonal med antallet tilstander systemet kan
være i. Å regne på entropi kan sammenliknes med å regne på sannsynligheter. For å regne å
entropiendringer bruker man Boltzmanns distribusjonslov: <math>p_i^* = \frac{e^{-\beta \epsilon_i}}{\sum_{i=1}^t e^{-\beta \epsilon_i}} = \frac{e^{-\beta \epsilon_i}}{q}</math>

Hvor q er partisjonsfunskjonen, som er summen av alle tilstander tilgjengelig for systemet under de gitte forutsetninger.

<math>q = \sum_{i=1}^t e^{-\beta \epsilon_i}</math>

===Kapittel 7: Termodynamiske drivkrefter===
I termodynamikken snakker man ofte om termodyamiske systemer, disse er definert som ulike typer listet opp på side 106 i boka.

Variabler i et system kan deles i intensive og ekstensive. En intensiv variabel er uavhengige av størrelsen på systemet, for eksempel temperatur. Temperaturen dobles IKKE når to like varme legoklosser settes sammen. En ekstensiv variabel er avhengig av størrelsen på systemet, for eksempel er antallet molekyler i to legoklosser satt sammen lik summen av molekylene i de to klossene.

Den fundamentale termodynamiske likingen for energi: <math>U = U\left(S,V,N\right)</math>

Såkalte fundamentallikinger kan skrives på derivatform, som for eksempel:

<math>dU = TdS - pdV + \sum_{j=1}^M \mu_j dN_j</math>

Ved å gjøre om på derivatformer og vet å bruke definisjoner på variabler kan man komme fram til andre fundamentallikninger på diffrensialform, for eksempel for entropi:

<math>dS = \left(\frac{1}{T}\right)dU + \left(\frac{p}{T}\right)dV - \sum_{j=1}^M \left(\frac{\mu_j}{T}\right) dN_j</math>

Ved å se på de matematiske definisjonene på temperatur, trykk og kjemisk potensial kan man si:
* 1/T gir tendensen til varmestrøm
* p/T gir tendensen for volumendring
* μ/T gir tendensen for utveksling av stoff
For at et system skal være i likevekt må dS=0 være oppfylt.
En kvasi-statisk prosess er en prosess som er så treg at verken tid eller hastighet spiller noen rolle. I en slik prosess er arbeidet utført ved konstant trykk og en volumendring fra Vi til Vf gitt ved:

<math>w = -\int_{V_a}^{V_b} p_{ext} dV = -p_{ext}\left(V_B - V_A\right)</math>

Termodynamikkens første lov; Endring i energi er summen av varme tilført og arbeid utført på systemet: <math>dU = \partial q + \partial w</math>

For kvasi-statiske prosesser gjelder også: <math>\partial w = -pdV</math>, <math>dS = \frac{\partial q}{T}</math>

Den siste likningen kalles ofte den termodynamiske definisjonen på entropi.

===Kapittel 8: Laboratoriebetingelser og frie energier===
2 hovedtyper fri energi:
* Helmholtz fri energi: F = U - TS
* Gibbs fri energi: G = H - TS

Akkurat som maksimering av entropien er en betingelse for likevekt, er også minimalisering av fri energi det.

H er entalpi som er summen av indre egergi og volum/trykk-arbeid:
<math>H = H\left(S, p, N\right) = U + pV dH = dU + pdV + Vdp</math>

Her følger en oversikt over fundamentale funskjoner hva likevekt angår:

{| class="wikitable"
|-
! Funksjon
! Ved likevekt
! Fundamental likning
! Definisjon
|-
| U(S,V,N)
| min
| <math>dU = TdS - pdV + \sum_j \left(\mu_j dN_j\right)</math>
|
|-
| S(U,V,N)
| maks
| <math>dS = \left(\frac{1}{T}\right)dU + \left(\frac{p}{T}\right)dV - \sum_j \left(\frac{\mu_j}{T}\right) dN_j</math>
|
|-
| H(S,p,N)
| min
| <math>dH = TdS + VdP - \sum_j \left(\mu_j dN_j\right)</math>
| H = U + pV
|-
| F(T,V,N)
| min
| <math>dF = -SdT - pdV + \sum_j \left(\mu_j dN_j\right)</math>
| F = U - TS
|-
| G(T,p,N)
| min
| <math>dG = -SdT + Vdp + \sum_j \left(\mu_j dN_j\right)</math>
| G = H - TS
|-
|}

Varmekapasitet ved konstant volum:

<math>C_V = \left(\frac{\partial q}{\partial T}\right)_V = \left(\frac{\partial U}{\partial T}\right)_V = T \left(\frac{\partial S}{\partial T}\right)_V</math>

Varmekapasitet ved konstant trykk:

<math>C_p = \left(\frac{\partial q}{\partial T}\right)_p = \left(\frac{\partial H}{\partial T}\right)_p = T \left(\frac{\partial S}{\partial T}\right)_p</math>

== Eksterne linker ==

*[http://www.ntnu.no/studier/emner?emnekode=TKJ4215 NTNUs fagbeskrivelse]
*[http://www.ntnu.no/studieinformasjon/timeplan/h08/?emnekode=TKJ4215-1 Timeplan Høsten 08]

[[Kategori:Obligatoriske emner]]
[[Kategori:Fag 4. semester]]
[[Kategori:Fag 5. semester]]
[[Kategori:Fag]]

Diskusjon:Optiske mikropskop

2009-05-25T15:10:52Z

Audunnys:

Ligger en lik side her: [[Optisk_mikroskopi]]

Jeg foreslår at de slåes sammen og at en av de slettes

Enig. Dersom innholdet i de to er likt er det bare å gjøre den ene til en ## REDIRECT til den andre. --[[Bruker:Goranb|Goranb]] 25. mai 2009 kl. 14:28 (UTC)

Merged and moved. --[[Bruker:Audunnys|Audunnys]] 25. mai 2009 kl. 15:10 (UTC)

Optiske mikropskop

2009-05-25T15:10:15Z

Audunnys: Omdirigerer til Optisk mikroskopi

#REDIRECT [[Optisk_mikroskopi]]

Optisk mikroskopi

2009-05-25T15:08:25Z

Audunnys: Endringer gjort av ingrhal på Optiske_mikroskop

== Oppsett ==
Består av en kilde (lyspære), "condenser" linser og aperturer, objektivlinser og aperturer og et kamera. Condenser linsen fokuserer lyset til et fokal punkt - back focal plane, mens aperturen begrenser mengden lys. Ved å sette aperturen til at bare litt lys kommer inn øker man kontrasten, men intensiteten minker. Objektivlinsen bestemmer forstørrelsen og er avhenging av den numeriske aperturen (NA). For å øke lysstyrken kan man øke NA, men dette vil samtidig føre til en kortere "working distance".

== Oppløsning, forstørring og kontrast==
Oppløsning er gitt av Rayleighs kriterium:
<math>r=0.61\frac{\lambda}{\mu sin \alpha}</math>
der <math>\lambda</math> er bølgelengden, <math>\mu</math> er brytningsindeksen og <math>\alpha</math> er halve aperturevinkelen. <math>\mu sin \alpha</math> er gitt som den numeriske aperturen NA, som kan stilles inn på mikroskopet.
Oppløsningen er definert som den minste avstand man kan skille to punkter. Oppløsningen kan økes ved å minimerer bølgelengden eller maksimere den numeriske aperturen.

Forstørring er definert som <math>M=\frac{u}{v}</math> der u er størrelsen på bilde og v er størrelsen på objektet.

Kontrast er definert som <math>C= \frac{I_{feature}- I_{background}}{I_{background}}</math>

Depth of field er dybden man fremdeles har objektet i fokus og er gitt ved: <math>d=r tan \alpha</math>. Økende NA (økende kontrast) gir dermed mindre depth of field.

Depht of focus er dybden man fremedeles har bildet i fokus, og er gitt ved:<math>D=M^2d</math> der M er forstørrelsen og d er depth of field.

Avik i oppløsningen er gitt ved sfæriske og kromatiske avik (spherical and cromatic aberrations). Sfæriske avik kommer fra at stråler i forskjellig avstand fra den optiske aksen (forskjellig vinkel) vil fokuseres ved forskjellige fokal punkt. Der en stråle lengre unna aksen vil fokuseres på et punkt nærmere linsen. Kromatiske avik kommer fra at stråler med forskjellig bølgelengde vil fokuserers ved forskjellige fokalpunkt. En stråle med mindre bølgelengde vil fokuseres på et punkt nærmere linsen. Kromatisk avvik kan forsvinne ved bruk av monokromatisk lys.

Astigmatisme kommer fra manglende aksial symmetri ved objektiv linsene, noe som også fører til en usikkerhet i fokalpunktet. Dette kan som regel korrigeres ved å justere linsene.

==Teknikker==
===Bright field===
Bruker lys normalt på prøven, reflektert lys blir dermed lyse felt, mens spredd lys vil spres utenfor linsa, og opptre som mørke felt.
===Dark field===
Setter for en aperture slik at lyset kommer på skrått inn mot prøven. Nå blir altså spredd lys til hvite felt, og reflekterlys til mørke felt. Dark field har større kontrast pga at bakgrunnen er mørk (intensiteten er null).
===Phase contrast===
Bruker her at en høydeforskjell i prøven gir en forskjellig veilengde for lyset, og dermed forskjellig fase. Denne forskjellen i fase brukes til å lage kontrast. For å måle forskjellen brukes en faseplate som skifter lyset enda mer. Denne kontrasten er svært god for prøver med lik brytningsindeks som bakgrunnen, for eksempel biologiske prøver.

Fagoversikt

2009-05-13T11:25:29Z

Audunnys: /* 1. klasse */

For Studiehåndbok for teknologistudiet (sivilingeniør) ved NTNU 2009-2010 se [http://www.ntnu.no/studier/studiehandbok/teknologi her]. Dette inneholder overgangsordinger for 3. klasse i 2009/2010.

== Felles obligatoriske emner i fagplanen ==

=== 1. klasse ===

{| class="wikitable sortable"
|-
! Fagkode
! Emnetittel
! Semester
! Studiepoeng
|-
| [[TDT4105]]
| Informasjonsteknologi, GK
| 1. Høst
| 7,5
|-
| [[TFE4220]]
| Nanoteknologi intro
| 1. Høst
| 7,5
|-
| [[TMA4100]]
| Matematikk 1
| 1. Høst
| 7,5
|-
| [[TFY4115]]
| Fysikk
| 1. Høst
| 7,5
|-
| [[TMA4105]]
| Matematikk 2
| 2. Vår
| 7,5
|-
| [[TMA4115]]
| Matematikk 3
| 2. Vår
| 7,5
|-
| [[TMT4110]]
| Kjemi
| 2. Vår
| 7,5
|-
| [[EXPH0001]]
| Filosofi og vitenskapsteori
| 2. Vår
| 7,5
|-
|}

=== 2. klasse ===

{| class="wikitable sortable"
|-
! Fagkode
! Emnetittel
! Semester
! Studiepoeng
|-
| [[TBT4160]]
| Organisk kjemi og boikjemi
| 3. Høst
| 7,5
|-
| [[TFE4180]]
| Halvlederteknologi
| 3. Høst
| 7,5
|-
| [[TMT4185]]
| Materialteknologi
| 3. Høst
| 7,5
|-
| [[TMA4130]]
| Matematikk 4N
| 3. Høst
| 7,5
|-
| [[TFE4120]]
| Elektromagnetisme
| 4. Vår
| 7,5
|-
| [[TKP4115]]
| Overflate- og kolloidkjemi
| 4. Vår
| 7,5
|-
| [[TKJ4215]]
| Statistisk termodynamikk i kjemi og biologi
| 4. Vår
| 7,5
|-
| [[TMA4245]]
| Statistikk
| 4. Vår
| 7,5
|-
|}

=== 3. klasse ===

{| class="wikitable sortable"
|-
! Fagkode
! Emnetittel
! Semester
! Studiepoeng
|-
| [[TFY4170]]
| Fysikk 2
| 5. Høst
| 7,5
|-
| [[TFY4335]]
| Bionanovitenskap
| 5. Høst
| 7,5
|-
| [[TFY4185]]
| Måleteknikk
| 5. Høst
| 7,5
|-
| [[TMT4320]]
| Nanomaterialer
| 5. Høst
| 7,5
|-
| [[TFY4220]]
| Faste stoffers fysikk (erstatter TFE4215, er like)
| 6. Vår
| 7,5
|-
| [[TIØ4257]]
| Teknologiledelse
| 6. Vår
| 7,5
|-
|}

=== 4. klasse ===

{| class="wikitable sortable"
|-
! Fagkode
! Emnetittel
! Semester
! Studiepoeng
|-
|
| Perspektivemne
| 7. Høst
| 7,5
|-
| [[Eksperter i team]]
| Eksperter i team
| 8. Vår
| 7,5
|-
| [[TFY4330]]
| Nanoverktøy (Revideres)
| 8. Vår
| 7,5
|-
|}

=== 5. klasse ===

{| class="wikitable sortable"
|-
! Fagkode
! Emnetittel
! Semester
! Studiepoeng
|-
|
| Ikke-teknologisk emne
| 9. Høst
| 7,5
|-
|
| Fordypningsemne og -proskjekt
| 9. Høst
| 22,5
|-
|
| Masteroppgave
| 10. Vår
| 30
|-
|}

==Emner for retning Bionano ==

=== 3. klasse ===

{| class="wikitable sortable"
|-
! Fagkode
! Emnetittel
! Semester
! Merknad
! Studiepoeng
|-
| [[TKP4115]]
| Overflate- og kolloidkjemi
| 6. Vår
|
| 7,5
|-
| [[TBT4110]]
| Mikrobiologi
| 6. Vår
|
| 7,5
|-
| [[TFY4195]]
| Optikk
| 6. Vår
|
| 7,5
|-
| [[TFY4260]]
| Cellbiologi og cellulær biofysikk
| 6. Vår
| Anbefalt
| 7,5
|-
| [[TMM4100]]
| Materialteknikk I
| 6. Vår
|
| 7,5
|-
| [[TMM4175]]
| Polymerer og kompositter
| 6. Vår
|
| 7,5
|-
|}

=== 4. klasse ===

{| class="wikitable sortable"
|-
! Fagkode
! Emnetittel
! Semester
! Merknad
! Studiepoeng
|-
| [[MOL3014]]
| Nanomedisin I
| 7. Høst
| Obligatorisk
| 7,5
|-
| [[MOL3005]]
| Immunologi
| 7. Høst
|
| 7,5
|-
| [[TBT4102]]
| Biokjemi 1
| 7. Høst
|
| 7,5
|-
| [[TBT4135]]
| Biopolymerkjemi
| 7. Høst
| (1)
| 7,5
|-
| [[TFY4265]]
| Biofysiske mikroteknikker
| 7. Høst
| Anbefalt
| 7,5
|-
| [[TFE4160]]
| Elektrooptikk og lasere
| 7. Høst
|
| 7,5
|-
| [[MOL3015]]
| Nanomedisin II
| 8. Vår
| Obligatorisk
| 7,5
|-
| [[MOL3007]]
| Funksjonell genomforskning
| 8. Vår
|
| 7,5
|-
| [[TFY4195]]
| Optikk
| 8. Vår
|
| 7,5
|-
| [[TOKS3001]]
| Medisinsk toksikologi
| 8. Vår
|
| 7,5
|-
| [[TBT4110]]
| Mikrobiologi
| 8. Vår
|
| 7,5
|-
| [[TEP4100]]
| Fluidmekanikk
| 8. Vår
|
| 7,5
|-
|}

(1) Anbefalt emne for studenter som planlegger fordypningsprosjekt eller master ved Institutt for bioteknologi.

==Emner for retning Nanomaterialer ==

=== 3. klasse ===

{| class="wikitable sortable"
|-
! Fagkode
! Emnetittel
! Semester
! Merknad
! Studiepoeng
|-
| [[TKP4115]]
| Overflate- og kolloidkjemi
| 6. Vår
| Obligatorisk
| 7,5
|-
| [[TKP4190]]
| Fabrikasjon og anvendelse av nanomaterialer
| 6. Vår
| (1)
| 7,5
|-
| [[TFY4195]]
| Optikk
| 6. Vår
|
| 7,5
|-
| [[TKJ4166]]
| Kjemisk bindingsteori og spektroskopi
| 6. Vår
|
| 7,5
|-
| [[TKP4130]]
| Polymerkjemi
| 6. Vår
|
| 7,5
|-
| [[TMT4285]]
| Hydrogenteknologi, brenselceller og solceller
| 6. Vår
|
| 7,5
|-
| [[TDT4100]]
| Objektorientert programmering
| 6. Vår
|
| 7,5
|-
|}

(1) Obligatorisk, emnet må velges i 3. eller 4. årskurs.

=== 4. klasse ===

{| class="wikitable sortable"
|-
! Fagkode
! Emnetittel
! Semester
! Merknad
! Studiepoeng
|-
| [[TFE4145]]
| Elektronfysikk
| 7. Høst
|
| 7,5
|-
| [[TFY4300]]
| Energi og miljøfysikk
| 7. Høst
|
| 7,5
|-
| [[TKP4155]]
| Reaksjonskinetikk og katalyse
| 7. Høst
|
| 7,5
|-
| [[TMT4145]]
| Keramisk material vitenskap
| 7. Høst
|
| 7,5
|-
| [[TFY4250]]
| Atom- og molekylfysikk
| 7. Høst
|
| 7,5
|-
| [[TMT4155]]
| Heterogene likevekter og fasediagram
| 7. Høst
|
| 7,5
|-
| [[TFE4160]]
| Elektrooptikk og lasere
| 7. Høst
| (1)
| 7,5
|-
| [[TKJ4205]]
| Molekylmodellering
| 7. Høst
| (1)
| 7,5
|-
| [[TMT4222]]
| Metallenes mekaniske egenskaper
| 7. Høst
| (1)
| 7,5
|-
| [[TMT4322]]
| Solceller
| 8. Vår
|
| 7,5
|-
| [[TMT4245]]
| Funksjonelle materialer
| 8. Vår
|
| 7,5
|-
| [[TFY4200]]
| Optikk, videregående kurs
| 8. Vår
|
| 7,5
|-
| [[TFE4230]]
| Nanofotonikk
| 8. Vår
|
| 7,5
|-
| [[TEP4220]]
| Energi og miljøkonsekvensanalyse
| 8. Vår
|
| 7,5
|-
| [[TFY4245]]
| Faststoff-fysikk, videregående kurs
| 8. Vår
|
| 7,5
|-
| [[TKP4190]]
| Fabrikasjon og anvendelse av nanomaterialer
| 8. Vår
| (2)
| 7,5
|-
| [[TFE4210]]
| Nanoelektronikk
| 8. Vår
| (1)
| 7,5
|-
| [[TKP4130]]
| Polymerkjemi
| 8. Vår
| (1), Gjelder kun 2009/2010
| 7,5
|-
|}

(1) Ikke hensyn ved time- og eksamensplanlegging.

(2) Obligatorisk, emnet må velges i 3. eller 4. årskurs.

==Emner for retning Nanoelektronikk ==

=== 3. klasse ===

{| class="wikitable sortable"
|-
! Fagkode
! Emnetittel
! Semester
! Merknad
! Studiepoeng
|-
| [[TFY4195]]
| Optikk
| 6. Vår
| Anbefalt
| 7,5
|-
| [[TDT4100]]
| Objektorientert programmering
| 6. Vår
|
| 7,5
|-
| [[TDT4102]]
| Prosedyre- og objektorientert programmering
| 6. Vår
|
| 7,5
|-
| [[TFY4215]]
| Kjemisk fysikk/kvantemekanikk
| 6. Vår
|
| 7,5
|-
| [[TFY4235]]
| Numerisk fysikk
| 6. Vår
|
| 7,5
|-
| [[TKP4115]]
| Overflate og kolloidkjemi
| 6. Vår
|
| 7,5
|-
|}

=== 4. klasse ===

{| class="wikitable sortable"
|-
! Fagkode
! Emnetittel
! Semester
! Merknad
! Studiepoeng
|-
| [[TFY4250]]
| Atom- og molekylfysikk
| 7. Høst
|
| 7,5
|-
| [[FY3114]]
| Funksjonelle materialer
| 7. Høst
|
| 7,5
|-
| [[TFE4145]]
| Elektronfysikk
| 7. Høst
| Anbefalt
| 7,5
|-
| [[TFE4160]]
| Elektrooptikk og lasere
| 7. Høst
|
| 7,5
|-
| [[TFE4225]]
| MEMS-design
| 7. Høst
|
| 7,5
|-
| [[TFY4205]]
| Kvantemekanikk
| 7. Høst
|
| 7,5
|-
| [[TFE4230]]
| Nanofotonikk
| 8. Vår
|
| 7,5
|-
| [[TFY4340]]
| Mesoskopisk fysikk
| 8. Vår
|
| 7,5
|-
| [[TFE4165]]
| Anvendt fotonikk
| 8. Vår
|
| 7,5
|-
| [[TFE4210]]
| Nanoelektronikk
| 8. Vår
| Anbefalt
| 7,5
|-
| [[TFY4210]]
| Anvendt kvantemekanikk
| 8. Vår
|
| 7,5
|-
| [[TFY4245]]
| Faststoff-fysikk, videregående kurs
| 8. Vår
|
| 7,5
|-
|}

==Emner utenom fagplanen==

{| class="wikitable sortable"
|-
! Fagkode
! Emnetittel
! Studiepoeng
|-
| [[NEVR2010]]
| Innføring i nevrovitenskap
| 15
|-
| [[NEVR2010|NEVR2020]]
| Innføring i nevrovitenskap
| 7,5
|-
| [[MFEL1010]]
| Innføring i medisin for ikke-medisinere
| 7,5
|-
| [[FY3020]]
| Romteknologi I
| 7,5
|-
| [[TTT4235]]
| Romteknologi II
| 7,5
|-
|}

==Eldre fagplaner==
[[Emner i fagplanen 2008/2009]]

Hovedside

2009-05-13T10:53:47Z

Audunnys:

{| width="100%"
|-
|style="vertical-align:top" |


<div style="margin: 0 10px 0 0; border: 2px solid #dfdfdf; padding: 0 1em 1em 1em; background-color:#f8f8ff; ">
===Velkommen til Nanowiki!===
[[Wiki#Nanowiki|Nanowiki]] er en [[Wiki#Fagwiki|fagwiki]] for [[MTNANO]], sivilingeniørstudiet i [[nanoteknologi]] ved NTNU. Wikien er driftet av [[Timini]], og inneholder [[Special:Statistics|{{NUMBEROFARTICLES}}]] artikler.
</div>


<div style="margin: 1em 10px 0 0; border: 2px solid #dfdfdf; padding: 1em 1em 1em 1em; background-color:#f8f8ff; ">
===Om nanoteknologistudiet===
Sivilingeniørstudiet i nanoteknologi er et tverrfaglig studie som gir studentene bred kompentanse innenfor fysikk, kjemi, materialteknologi, elektronikk og biologi, med spesialisering avhengig av valg av fordypning de siste tre årene av studiet. Se også [http://www.ntnu.no/studier/nanoteknologi NTNUs beskrivelse av studiet] og [[Fagoversikt|fagoversikten]] for mer informasjon om hvilken kompetanse studentene kan bidra med.
</div>



<div style="font-variant: small-caps; text-align: center; margin: 10px 10px 0 0; padding: 0 1em 0 1em; ">
[[:Kategori:Fag|Fag]] | [[:Kategori:Obligatoriske emner|Obligatoriske emner]] | [[:Kategori:Utveksling|Utveksling]]</div>

<div style="text-align: center; margin: 0 10px 0 0">''[[Spesial:Kategorier|Bla gjennom kategoriene]]''</div>



<div style="margin: 10px 10px 0 0; border: 2px solid #dfdfdf; padding: 0em 1em 1em 1em; background-color: #f8f8ff; ">
<div style="width:100%;">
===Hvordan kan jeg hjelpe?===
For å komme i gang med å redigere artikler, se [[Hjelp:Hjelp|Hjelp]]. Husk også å lese [[Retningslinjer for nanowiki]] før du oppretter artikler. Deretter kan du ta en titt på [[Spesial:Ønskede_sider|listen over ønskede sider]] for inspirasjon.

For å kunne redigere artikler må du være registrert bruker og logget inn. I utgangspunktet er alle medlemmer av [[Timini]] lagt til som brukere, men dersom noen andre (forelesere, stud.asser, andre som har fag sammen med MTNANO) ønsker å bidra, ta kontakt med [[infodep]] på wiki alfakrøll timini.no for å få tildelt brukertilgang.
</div>
</div>



| width="40%" style="vertical-align:top" |



<div style="margin:0; border:2px solid #dfdfdf; padding: 0em 1em 1em 1em; background-color:#efefdf; text-align:left;">
====English info====
<div style="font-size:small; margin-left:1em;">
This wiki is run by Timini, the student association for the nanotechnology students at [[NTNU]]. The wiki is primarily in Norwegian, although some English content exists. If you want to contribute to the wiki or have any questions or feedback, please contact us at our e-mail address; wiki [at] timini [dot] no.

For information about the courses studied in the nanotechnology study program and which competence the students have, check out [http://www.ntnu.no/studies/nanotechnology NTNU's description of the program], and our [[Fagoversikt|course overview]] (only in Norwegian).
</div></div>


<div style="margin: 10px 0 0 0; border:2px solid #dfdfdf; padding: 0em 1em 1em 1em; background-color:#dfefdf; ">
====Visste du at ...====
<div style="font-size:small">
{{nye}}
</div>
</div>

<div style="margin:10px 0 0 0; border:2px solid #dfdfdf; padding: 0em 1em 1em 1em; background-color:#efefdf; text-align:left;">
====Fagspørsmål====
<div style="font-size:small; margin-left:1em;">
Hvis noen har mer dyptgående spørsmål rundt fag, eller har forslag til endringer/forbedringer av fagplanen, oppfordres det til å ta kontakt med [[fagteamet]].
</div></div>

|} __NOTOC__ __NOEDITSECTION__

Fil:Fox2.jpg

2009-01-31T14:34:32Z

Audunnys: Tester bildeopplasting

Tester bildeopplasting

TDT4102

2008-12-29T23:14:59Z

Audunnys: TDT4102 flyttet til TDT4102 - Prosedyre- og objektorientert programmering

#REDIRECT [[TDT4102 - Prosedyre- og objektorientert programmering]]

TDT4102 - Prosedyre- og objektorientert programmering

2008-12-29T23:14:59Z

Audunnys: TDT4102 flyttet til TDT4102 - Prosedyre- og objektorientert programmering

{{Infobox
|Fakta vår 2009
|*Foreleser: Trond Aalberg
*Stud-ass: ???
*Vurderingsform: Skriftlig eksamen (100 %)
*Eksamensdato: 6. juni
*Pensum: Absolute C++, Walter Savitch. Third ed., Pearson Addison Wesley 2008. ISBN-10 0-321-49438-5, ISBN-13 978-0-321-49438-2
}}

{{Infobox
|Øvingsopplegg vår 2009
|* Antall godkjente: ??/??
* Innleveringssted: ???
* Frist: ???
}}

Emner som tas opp i faget:

Programmeringsspråk og datamaskiner. Problemløsnings- og programmeringsmetodikk. Variable, datatyper og datastrukturer. Kontrollstrukturer. Prosedyrer, funksjoner, parameteroverføring. Filer og filbehandling, innlesing / utskrift. Rekursjon. Minneallokering. Pekere og dynamiske variable, lenkede lister, binære trær. Objekter og klasser, arv og innkapsling, metodekall, overstyring. Funksjons- og klassebiblioteker. Programmeringsspråket som brukes i kurset er C/C++.

== Eksterne lenker ==

*[http://www.ntnu.no/studier/emner?emnekode=TDT4102 NTNUs fagbeskrivelse]
*[http://www.ntnu.no/studieinformasjon/timeplan/v09/?emnekode=TDT4102-1 Timeplan Vår09]

[[Kategori:Valgbare emner]]
[[Kategori:Fag 6. semester]]
[[Kategori:Fag]]

TDT4102 - Prosedyre- og objektorientert programmering

2008-12-29T23:14:26Z

Audunnys: Ny side: {{Infobox |Fakta vår 2009 |*Foreleser: Trond Aalberg *Stud-ass: ??? *Vurderingsform: Skriftlig eksamen (100 %) *Eksamensdato: 6. juni *Pensum: Absolute C++, Walter Savitch. Third ed., Pear...

TFY4185 - Måleteknikk

2008-12-17T21:44:37Z

Audunnys: /* Chapter 4: Control and Feedback */ formatering

{{Infobox
|Fakta høst 2010
|*Foreleser: ???
*Stud-ass: ???
*Vurderingsform: Skriftlig eksamen (?? %), midtsemester (?? %), arbeider (?? %), prosjekt (?? %)
*Eksamensdato: ???
}}

{{Infobox
|Øvingsopplegg høst 2010
|* Antall godkjente: ??/??
* Innleveringssted: ???
* Frist: ???
}}

{{Infobox
|Lab høst 2010
|* Info om lab
}}

Dette faget er flyttet opp i 3. klasse f.o.m. neste skoleår(2009/2010).

== Fagets innhold ==
Elektroniske kretselementer:
*Enkle passive kretser
*Halvleder kretselementer
*Aktive kretser, operasjonsforsterkere
*Digitale kretser
Laboratorium i kretsteknikk:
*Bygging og utprøving av et utvalg av elektroniske kretser
*Datamaskinlaboratorium: Simulering av kretser med dataverktøy (PSpice)

== Vurderingsform ==
Det gis karakterene bestått/ikke bestått.
Faget har en (frivillig) semesterprøve som teller i endelig vurdering dersom den teller positivt.
For å ta avsluttende eksamen må man levere 5 av 6 øvinger, samt fullføre lab.

[[Kategori:Obligatoriske emner]]
[[Kategori:Fag 3. semester]]
[[Kategori:Fag 5. semester]]
[[Kategori:Fag]]

== Oppsummering av pensum ==

=== Kompendium: Gustafsson og Skullerud, TFY 4185 Lecture Notes 2008 ===
*Voltage and current dividers
**Om man har to impedanser i serie (<math>Z_1</math> og <math>Z_2</math>), er forholdet mellom spenning <math>V_0</math> over <math>Z_1</math> og spenning <math>V</math> over begge:
::<math>\frac{V_0}{V} = \frac{Z_1}{Z_2 + Z_1}</math>
**Om man har to impedanser i parallell (<math>Z_1</math> og <math>Z_2</math>), er forholdet mellom strøm <math>I_0</math> gjennom <math>Z_1</math> og strøm gjennom begge <math>I</math>:
::<math>\frac{I_0}{I} = \frac{Z_2}{Z_2 + Z_1}</math>
*Norton and Thevenin equivalents
**Thevenins theorem: Enhver krets med to poler uten andre aktive elementer enn spenningskilder og strømkilder, kan framstilles som en krets med en spenningskilde i serie med en resistans, <math>R_i</math>, som er den indre resistansen mellom polene.
::<math>V_T=</math> "open source voltage", spenningen mellom polene når de er åpne. Finnes ved hjelp av f.eks. Kirchhoffs lover.
::<math>R_T=R_i</math> "output resistance", total resistansen i kretsen. Finnes ved å kortslutte alle spenningskilder og sette inn åpne ender i stedet for strømkilder.
**Nortons theorem: Enhver krets med to poler uten andre aktive elementer enn spenningskilder og strømkilder, kan framstilles som en krets med en strømkilde i parallell med en resistans, <math>R_i</math>, som er den indre resistansen mellom polene.
::<math>I_N</math> "short circuit current", strømmen når polene er kortsluttet. Kan også finnes ved hjelp av f.eks. Kirchoffs lover.
::Sammnehengen mellom Thevenin og Norton<math>I_T=\frac{V_T}{R_T}</math>
*Impedance matching, input and output
*Maximum power transfer to the load (both AC and DC cases)
*Phase shift induced by passive components
*Resonant circuits: Give an example of a simple resonant circuit, its resonant frequency and what
the Q value is and what it means.

=== Lærebok: Neil Storey, Electronics A Systems Approach ===
==== Chapter 3: Amplification ====
*Definition of amplification
**Forsterkningen av en størrelse er forholdet mellom den forsterkede størrelsen <math>X_o</math> og den uforsterkede <math>X_i</math>. Vi definerer:
:: voltage gain (<math>A_V</math>) <math> = \frac{V_o}{V_i}</math>
:: current gain (<math>A_I</math>) <math> = \frac{I_o}{I_i}</math>
:: power gain (<math>A_P</math>) <math> = \frac{P_o}{P_i}</math>
**Ofte oppgis gain i dB. Da har vi:
:: voltage gain (<math>A_V</math>) <math> = 10 \cdot \log(\frac{V_o}{V_i})</math>
:: current gain (<math>A_I</math>) <math> = 10 \cdot \log(\frac{I_o}{I_i})</math>
:: power gain (<math>A_P</math>) <math> = 10 \cdot \log(\frac{P_o}{P_i}) = 20 \cdot \log(\frac{V_o}{V_i})</math>
*Simple High-pass and Low-pass filters including their Bode dagrams (Both amplification and
phase)

==== Chapter 4: Control and Feedback ====
*Negative feedback
I et generelt elektronisk tilbakemeldingssystem (feedback) kan vi utrykke ytelsen (gain) som
::<math>G=\frac{A}{1+AB}</math> der A er "forward path" og B er "feedback path". Se utledning s.97 i boka.
::Hvis AB er negativ får vi positiv "feedback". I spesialtilfellet <math>AB=-1</math>, går G mot uendelig, noe som brukes i produksjonen av oscillatorer.
::Hvis AB er positiv får vi negativ "feedback". Når AB er mye større enn 1, kan vi forenkle G til:
::<math>G=\frac{1}{B}</math>
::G blir dermed bare avhengig av "feedback path". For å få et stabilt system må "feedback path" konstrueres av bare passive komponenter, og B må være mindre enn 1 for å få en positiv "gain".
*The advantage of using feedback amplifiers
**Gain: Siden <math>AB>>1</math>, er <math>A>>\frac{1}{B}</math>, altså er "open-loop gain">>"closed-loop gain". Feedback reduserer altså "gain" med en faktor <math>1+AB</math>
**Frequency response: Ytelsen (gain) av en forsterker minker ved høye og lave frekvenser. Ved negativ "feedback" (og AB mye større enn 1> avhenger "gain" nesten bare av "feedback path", og denne effekten vil minke betraktelig. Vi får altså et mer stabilt system ved høye og lave frekvenser, dvs båndbredden øker for systemet.
**Input and Output resistance: Et negativt "feedback"system vil prøve å holde "output" konstant, uansett endringer i miljøet (f.eks. når man setter på en "load"). Dette gjør den ved å øke/minke "input" og "output"resistans (vanligvis med en faktor AB+1)
***Hvis feedback er "output"spenningen => redusering av "output"resistans
***Hvis feedback er "output"strømmen => økning av "output"resistans
***Hvis feedback er en spenning relatert til output => øking av "input"resistans
***Hvis feedback er en strøm relatert til output => redusering av "input"resistans
**Distortion, Noise: "Distortion" og støy fra forsterkeren reduseres av negativ feedback.
**Stability: A og B har ikke bare en størrelse, de har også en fasevinkel. Hvis A eller B opplever et faseskift på 180 grader, skiftes fortegnet på A eller B, og AB blir negativ. Man opplever dermed positiv feedback, i stedet for negativ. Hvis <math>AB=-1</math> begynner systemet å oscillere (se kap. 11), og systemet blir ustabilt.

==== Chapter 5: Operational Amplifiers ====
*A simple operational amplifier based non-inverting amplifier
**Non-inverting:(se figur s. 118) Får <math>V_i</math> inn på plusssiden, og feedback på minussiden av forsterkeren.
::"Gain" er gitt ved <math>G=\frac{R_1+R_2}{R_2}</math>
**Unity gain: (figus s. 122) <math>R_1=0</math> og <math>R_2=</math>∞
*A simple operational amplifier based inverting amplifier
**Inverting:(se figur s. 120) Får både <math>V_i</math> og feedback inn på minussiden av forsterkeren.
::"Gain" er gitt ved <math>G=-\frac{R_1}{R_2}</math>
**Current-to-voltage converter: (figur s. 123) <math>R_2=0</math> og <math>I_i</math> inn på minussiden. <math>V_0=-I_iR</math>

*Characteristics for an ideal operational amplifier compared to a non-ideal (real world) operational amplifier

*Frequency dependence of amplification and how it is influenced by feedback
*How the input and output impedance are influenced by feedback

==== Chapter 6: Semiconductors and Diodes ====
*How the [[ideal diode]] work and its typical applications
**One could characterise an ideal diode as a component that conducts no current when voltage is applied across it in one direction, but appears as a short circuit when a voltage is applied in the other direction.
**Diode circuit symbol: an arrow pointing in the direction of forward current.
**Wide range of applications: rectification of alternating voltages (AC to DC), Voltage control (Zener diodes), demodulation (making an AM signal meaningful), signal clamping.
*Describe the electrical properties of insulators, semi-conductors and metals in a simple energy band model
**Semi-conductors: Fermi level is between the conduction and valence bands, i.e. in an area of low density of states. The valence and conduction bands are close enough (~less than 2-3 eV) to allow considerable excitation of electrons by increasing temperature or doping.
*Give a simple description of “doping” and how it influences the material
**In silicon: boron-> p-type, phosphorus-> n-type.
*How a PN diode functions and its I-V characteristic
** Due to diffusion of charge in a pn-junction a voltage barrier is created between the p and n type semiconductors. This voltage barrier can either be enhanced or decreased depending on the direction current is sent through the depletion layer.
*The function of a Zener diode
**Voltage control (protection of a circuit from too high voltage values, or to make voltage output constant).

==== Chapter 7: Field-Effect Transistors ====
*The construction and function of the different sorts of [[field-effect transistor]]
** Husk på at navngivingen Drain og Source er '''motsatt av det man skulle tro''', dvs positiv strøm går fra Drain til Source.
** '''MOSFET''': Bruker figur 7.4 s 173: Er en positiv spenning V(ds)=V(d) - V(s) mellom Drain og Source. Tilkoblingen på høyre side er Substratet, denne er gjerne jordet og setter nullpunkt for systemet (den er heller ikke noe videre forklart i boka, så tipper den har lite relevans). Gaten på venstre side er isolert fra halvlederen ved et MO-lag(MetallOksid). Setter vi på en positiv spenning over gaten, vil de negative ladningsbærerne fra P-feltet "trekkes" over mot N-feltet, og depletion-layeret vil bli mindre, dermed blir det flere ladningsbærere som kan sende strøm, og det går mer strøm. Om spenningen er negativ, vil på samme måte elektronene i N-laget "skyves" inn i P-laget, dvs depletion-lageret blir større.
*** '''DE MOSFET''' - Depletion - Enhancement MOSFET: som beskrevet overfor, '''kan gi signal både for positiv og negativ Gate-spenning.'''
*** '''Enhanced MOSFET''' - her går P-laget i figur 7.4 fra høyre side av transistoren og helt inn til gaten, dvs det er ikke et N-lag mellom P-laget og gaten. Poenget med denne MOSFETen er at man '''hele tiden må ha en positiv spenning''' på gaten. Da dras de få ledende elektronene i P-laget inn mot gaten, og det lages en "bro" av elektroner som kan lede strøm mellom Source og Drain.
** '''JFET''': Bruker figur 7.7 s 175: I denne transistoren må Gate-spenningen '''alltid være negativ''' for at det ikke skal gå noen strøm gjennom gaten(her er det ikke noe MO-lag mellom gaten og halvlederen). Poenget med denne FET-en er at man bruker Reverse Bias-egenskapene ved halvlederen til å regulere strømmen mellom Source og Drain. Dvs, jo mer spenning man setter på "feil vei" fra Source til Gate, jo større vil depletion-laget være (figur b), og dermed er det færre ladningsbærere som kan sende strøm fra Drain til Source. Hadde man satt på en positiv strøm, ville strømmen gå fra Gate til Source som i en diode.
** '''Symboler''': Sammenlign figur 7.3 og figur 7.5: Dette er logisk, for MOSFET er det ikke kontakt mellom Gate og Source-Drain. Samtidig er Enhancement tegnet med stiplet linje, for der er det ikke kontakt mellom Source- og Drain-lagene. '''Generelt for alle transistorsymboler går pilen i Substrate eller Gain fra P-dopet til N-dopet i den fysiske transistoren''' På samme måte for figur 7.6 og 7.8: Her er Gaten fysisk koblet til transistoren, så også i symbolet.
*How a transistor is used in a simple amplifier
*The I-V characteristics for the different sorts of field-effect transistors

==== Chapter 8: Bipolar Juction Transistors ====
*How a bipolar transistor works
** Tar for oss en NPN-transistor (for figur, se boka s. 224)
** Denne består av et tungt N-dopet Emitter-lag (tilsvarer Source i MOSFET), et tynt, relativt svakt P-dopet Base-lag (tilsvarer Gate), og et N-dopet Collector-lag (Drain).
** Har positiv spenning fra Collector til Emitter - Om Base er åpen, vil det gå en liten strøm ''I(CEO)'' fra Collector til Emitter. Setter man opp en positiv strøm fra Base til Emitter, vil elektroner gå motsatt vei, fra Emitter til Base, som i en vanlig diode. Forskjellen er at siden Emitter er sterkt N-dopet og Base er svakt P-dopet, vil '''ladningsbærerne i Base-laget også være elektroner'''. I overgangen mellom Base og Collector vil det som i alle p-n-overganger være et depletion layer med positiv ladning på N-siden og negativ ladning på P-siden. '''Siden P-laget er så tynt''', vil elektronene som kommer fra Emitter og over i P-laget merke et positivt elektrisk felt fra Collector-siden og bli trukket over til Collector. Strømmen fra B til E er liten sammenlignet med strømmen fra C til E.
** To viktige karakteristikker for en Bipolar Transistor:
*** '''Emitter et tungt dopet og Base er svakt dopet''' - siden det i dette P-N-systemet er flest negative ladningsbærere, vil ladningsbærerne i Base være elektroner, og disse vil tiltrekkes av det positive feltet i Collector.
*** '''Base er tynn''' - Dersom ikke Base var tynn, ville elektronene bare gått fra Emitter til Base som i en vanlig diode.
** En bipolar transistor gjør om et '''strømsignal''' til en ut-strøm, i motsetning til FET, der man bruker spenning som input.

==== Chapter 9: Power Electronics ====
*The different classes of power amplifiers
**Det viktige i dette kapitlet er hva slags ut-signal de forskjellige forsterkerklassene gir og hvor effektive de er. Dere kommer til å se en grei linearitet i dette, og klassene er logisk delt inn.
**Effekten måles i % og er gitt ved E=(Effekten forbrukt i lasten)/(Effekten fra kraftforsyningen)
***'''Klasse A''' (s 291 for illustrasjoner): En effektforsterker som overfører '''hele''' signalet fra inputen. Mindre fare for distortion, men effektiviteten har et maksimum på ca. '''25 prosent'''.
***'''Klasse B''' (s 292) : Overfører '''50 prosent''' av signalet fra inputen, dvs enten den positive eller negative delen av et sinussignal. Effektiviteten kan komme opp i '''78 prosent''', men faren for distortion er større.
***'''Klasse AB''' (s 292) : Overfører '''mellom 50 og 100 prosent''' av inn-signalet, kutter gjerne av toppen eller bunnen av sinussignaler. Effektiviteten et sted mellom A og B, og samme med mengden distortion.
***'''Klasse C''' (s 293) : Gir ut-signal for '''under 50 prosent''' av sinusbølgen, f.eks. signal for topp eller bunn i sinussignalet. Effektiviteten kommer '''opp mot 100 prosent'''.
***'''Klasse D''' (s 293) : Gir '''av eller på-signal''' med uendelig resistans når den er av, og null resistans når den er på.
*How TRIAC’s and thyristors are used within power control circuits
** '''En Thyristor''' (s 301) kan forstås som en sammensetning av to bipolare transistorer. Den fungerer slik at om man gir et signal i gaten, vil det gå strøm fra anoden(a) til katoden(c) så lenge V(a) - V(c) er positiv. Om spenningen snus, stopper signalet. Thyristorer brukes i en krets for å kun gi en del av en AC-strøm. Den må trigges i gaten for å starte, og så leder den strøm fram til spenningen blir negativ (s 302).
** '''En Triac''' er en bidireksjonal Thyristor, dvs den kan fungere både når spenningen fra (a) til (c) er negativ OG positiv, men den slår seg i begge tilfeller av når spenningen blir ~0.
*The different ways to convert AC-DC as well as the advantages and disadvantages of the different methods

==== Chapter 10: Analogue Signal Processing ====
*The difference between a Butterworth, Chebyshev and Bessel filter
** Side 317 - 319
**: '''Kort bakgrunn:''' Man kan dele elektriske filtre inn i passive og aktive. Aktive filtre inneholder en eller flere aktive komponenter, for eksempel en operasjonsforsterker. De tre filtrene beskrevet her er alle eksempler på aktive filtre. Foruten operasjonsforsterker(e), inneholder aktive filtre resistanser og kondensatorer (merk: ikke spoler). Ulike filterdesign gir ulike filteregenskaper. Dessverre er det ofte slik at én ''gunstig'' filteregenskap er forbundet med en annen ''ugunstig'' filteregenskap. Filterkretsen må derfor skreddersys slik at filteret får den egenskapen som er viktigst med tanke på dets funksjon.
**# '''Butterworth-filter'''
**#: Laget for å gi "flatest" mulig respons innenfor passband. Det vil si at gain skal være så lik som mulig for alle frekvenser som er innenfor passband.
**# '''Chebyshev-filter'''
**#: Laget for å få en skarp overgang i gain mellom passband og stopband. Det vil si at gain skal falle drastisk med én gang frekvensen til input-signalet er utenfor passband.
**# '''Bessel-filter'''
**#: Laget slik at faseforskjellen mellom input- og output-signal står i et lineært forhold til input-frekvensen. Dette gjør at alle frekvens-komponenter som går gjennom filteret (innenfor passband) forsinkes med det samme tidsintervallet. Fordelen med dette er at bølgeformen fra input-signalet bevares i output-signalet. Denne typen filter er derfor ideell når det er viktig å bevare en komplisert bølgeform (som består av flere ulike frekvens-komponenter).

*Sketch out a general measurement system, explain where you think the best places to filter the signal are and why

==== Chapter 11: Positive Feedback, Oscillatiors and Stability ====
*Positive feedback and the Barkhausen criteria
::"Gain" er gitt som <math>G=\frac{A}{1+AB}</math> (se kap. 4), og positiv feedback er når AB er negativ og mindre enn 1.
::Ved <math>AB=-1</math> får vi at G går mot uendelig. Da vil systemet generere en output, selv om det ikke finnes noen input. Vi får altså en oscillator. Forutsetningene for oscillering er gitt av Barkhausen kriteriene:
::1. Størrelsen av AB må være lik 1
::2. Faseskiftet av AB må være lik 180 grader, eller 180 pluss et heltall ganger 360 grader.

==== Chapter 12: Digital Systems ====
*The difference between combinational and sequential logic
*Reducing a logical expression with the aid of Boolean algebra or the Karnough diagram
==== Chapter 13: Sequential Logic ====
*The function and workings of: Bi-stable, mono-stable and astable sequential logic
*The function and workings of a shift register and counter
==== Chapter 14: Digital Devices ====
*How transistors are used within digital electronics
*The important parameters for the TTL and CMOS digital-logic families
*How one couples to an open collector logical circuit
==== Chapter 15: Array Logic ====
*The function of PLA, PAL, GAL, EPLD, PEEL, PROM, FPGA
*Describing the building up of a micro-computer

== Eksterne linker ==

*[http://www.ntnu.no/studier/emner?emnekode=TFY4185 NTNUs fagbeskrivelse]
*[http://www.ntnu.no/studieinformasjon/timeplan/h10/?emnekode=TFY4185-1 Timeplan Høst10]
*[http://www.hardware.no/artikler/guide_elektronikkens_verden_-_del_1/18842 Guide: Elektronikkens verden - del 1]
*[http://www.hardware.no/artikler/guide_elektronikkens_verden_-_del_2/20924 Guide: Elektronikkens verden - del 2]
*[http://www.hardware.no/artikler/guide_elektronikkens_verden_-_del_3/32707 Guide: Elektronikkens verden - del 3]

TMT4320 - Nanomaterialer

2008-12-15T16:53:48Z

Audunnys: /* LED */

{{Infobox
|Fakta høst 2008
|*Foreleser: Fride Vullum
*Stud-ass: Katja Ekroll Jahren og Ørjan Fossmark Lohne
*Vurderingsform: Skriftlig eksamen
*Eksamensdato: 18. desember
}}

{{Infobox
|Øvingsopplegg høst 2008
|* Antall godkjente: 6/12
* Innleveringssted: Utenfor R7
* Frist: Tirsdager 16:00 (?)
}}

Emnet skal gi en innføring i grunnleggende kjemisk prinsipper for å lage nanomaterialer. Stikkord: "Self-assembled" monolag ([[SAM]]) og hvordan disse kan formes ved myk litografi og "dip pen" nanolitografi, syntese av tredimensjonale multilag strukturer. Tynne filmer ved kjemisk gassfase deponering. Syntese av nanopartikler, nanostaver, nanorør og nanoledninger. Våtkjemiske syntese av oksidbaserte nanomaterialer. "Self-asembly" av kolloidale mikrokuler til fotoniske krystaller, porøse nanomaterialer, blokk-kopolymere som nanomaterialer. "Self assembly" av store byggeblokker til funksjonelle anordninger.

== Oppsummering av pensum ==
Her vil det etterhvert vokse fram et lite kompendium i faget. Dette følger i utgangspunktet pensumlista som gjelder for høsten 2008.

===Chapter 1: Nanochemistry Basics ===
Not terribly important.

===Chapter 2: Soft Lithography===
====Self-assembled monolayers (SAMs)====
*The typical example of a SAM is a layer of alkanethiols on a gold substrate.
*The S-H bond is cleaved by oxidation on the gold surface and a covalent Au-S covalent bond is formed.
*The alkanethiols are tilted off-axis from the normal. The angle depends on the surface. (30 ° for a {111} gold surface, 10 ° for a silver surface).
*The end group on the alkanethiols can be tailored to achieve different monolayer properties, thus modifying the surface properties of the structure.

====PDMS stamp====
* PDMS (PolyDiMethylSiloxane) is a soft elastic polymer.
* A master (casting) of the stamp, with the desired pattern, is made with electron or UV-lithography. The master is silanized and made hydrophobic so removing of the stamp becomes easier.
* Liquid PDMS is then poured into the master, after which it is cured and a finished PDMS stamp is removed from the master.
* The critical dimensions of the stamp are limited by the lithography techniques used, and for [[photolithography]] the wavelengths of the light used to expose the [[photoresist]] limits the dimensions. Typical CDs given are, for lateral dimensions within the range of 500nm-200µm, and for the height of patterns 200nm-20µm.
* The PDMS stamp can be dipped in alkanethiol solutions (or solutions of other molecules, collectively known as "chemical ink") and be stamped onto surfaces.
* PDMS stamps work on both planar and curved surfaces.
* For the stamp to properly print a pattern onto a surface, the molecules need to adhere to the stamp from the solution, but the affinity for binding to the surface has to be stronger.

====Hydrophilic / Hydrophobic stamps====
* The endgroup/terminal group on the alkanethiols (or other molecules used) determine the properties of the monolayer, f. ex. a OH-terminal group makes the monolayer hydrophilic, while a <math>CH_3</math>-group makes it hydrophobic.
* Wetability is determined by the polarity of the endgroups.
* By introducing a wetability gradient or abrupt changes in wetability, different effects can be obtained:
** Square drops, by having checkerboard square patterns of hydrophilic monolayers with hydrophobic lines inbetween, and condensating water onto the surface. This is called condensation figures and results from the condensation on the hydrophilic areas, when the substrate is cooled below the dew point. The diffraction pattern of the structure can be studied for obtaining information on the kinetics and structure of the water droplets. This can be used in biological sensing.
** Droplets "running uphill" by having wetability gradients. The droplets are moving towards the more hydrophilic areas, against the force of gravity.
** Nanoring arrays can be synthesized using the condensation figures as templates for molding. A solvent precursor which wets the regions between the microdroplets is added and then evaporated. Deposition of precursor occurs around the perimeter of the droplets. Finally, the water droplets is evaporated, and the precursor remains on the substrate as nanorings.
** Solid state patterning by dipping a SAM-patterned substrate in a precursor solution. This creates microdroplets with a predetermined precursor concentration, which on evaporation and vertical drying leaves behind an array of size-tunable solid precursor dots.

====Printing thin films====
* As long as the adhesion between the chemical ink and the substrate is stronger than the adhesion between the ink and the stamp, printing thin films is no problem
* Metal thin films can be evaporated onto a PDMS stamp (f. ex. gold). Evaporation gives homogenous and directional coatings, and no covering of the side walls on the stamp. This pattern is printed onto a SAM-primed substrate with exposed thiol groups (gold adheres strongly to the metal layer).
* This is a very gentle technique for metal film depositing, good for making contacts on fragile layers. Also good for making 3D stuctures by printing multiple layers. Also, there is no need for photoresist because the pattern is printed directly.

====Electrically contacting SAMs====
* Molecular electronic devices need to make good electrical contact with SAMs.
* Making electrical contacts by vapor deposition on the SAMs may sometimes be more convenient than thin-film printing with a PDMS stamp.
* Other, less gentle methods of metal deposition than printing with PDMS stamps (sputtering, CVD, etc) can cause the metal layer to penetrate the SAM and deposit on the substrate, or even diffuse into the substrate, introducing defects to the structure.
* Morale: Use stamps to deposit metals on SAMs!

====Patterning by photocatalysis====
* Photocatalysis is used to remove parts of a SAM (making patterns)
* Titania (<math>TiO_2</math>) can photocatalytically decompose organic molecules.
* A quartz slide patterned with titanium dioxide in the required pattern using ALD is pressed against a wafer with the SAM on it.
* The assembly is exposed to UV radiation, triggering the degradation of the (organic) SAM. When titania is exposed to UV, radiation free radicals are created, which react with the organic molecues, removing the parts of the SAM that is in contact with the titania. Thus, the substrate in these areas is revealed.

===Kapittel 3: Building layer-by-layer===

====Electrostatic superlattices====
* LbL multilayer films formed by alternate immersion in suspensions of opposite charges.
* A primer layer with a charge adheres to the substrate. The substrate is then dipped in a solution of polyelectrolytes of opposite charge from the primer layer. This process can be repeated numerous times in order to get the desired thickness or functionality of the film.
* As the amount and identity of constituents of each layer can be controlled, a composition gradient can easily be constructed throughout the structure.
* Any species bearing multiple ionic charges can be layered.
* Can be applied to curved surfaces like microspheres, enables applications like hollow spheres with a semipermeable cap.

====Some applications====
* Electrochromic layers (change color when a potential is applied), used in "smart windows" for instance
* Construction of cantilevers for AFMs and similar equipment, using photolithography and LbL

====Analysis, measuring film thickness====
* Optical spectroscopy: If the substrate is transparent, and the film absorbs light at a certain wavelength, the film thickness can be found by monitoring the optical absorption as a function of number of layers. A dye can be introduced to ensure absorption. Easy to perform but hard to interpret - must know the observation area and extinction coefficient of the absorbing group.
* Ellipsometry: Film is probed by polarized light, and change in polarization in the reflected light is measured. This can be used to find the refractive index, thickness, roughness and orientation of a thin film. Ellipsometry works with films much thinner than the wavelength of light - down to atomic layers.
* Quartz crystal microbalance (QCM): Quartz (piezoelectric material) in an alternating electric field contracts/expands with a characteristic oscillation frequency. When mass is added to a QCM the frequency decreases, which correlates directly with the amount of mass added. This allows real-time thickness measurements when the density of the material is known. Works well for hard materials like metals and ceramics, but not for viscoelastic materials.
* Direct techniques: Label each layer with heavy metal atoms and image by TEM. Alternately, deposit a thin gold layer on top of the surface and image cross section by TEM.

====Non-electrostatic lbl assembly====
* LbL doesn't need electrostatic bridges - can use hydrogen bonding, ligand-receptor interactions or even covalent bonds.
* Example: DNA (adenine-thymine and guanine-cytosine bridges)
* Hydrogen bonds can be broken again by changing the pH, or can be strengthened by UV irradiation

====Low-pressure layers====
* Molecular beam epitaxy (MBE): Performed in ultrahigh vacuum, sources of constituents (elemental) are heated, and a thin film alloyed from the constituents is deposited. The result is a single crystal film with homogeneous thickness grown epitaxially on the substrate. The substrate should have a similar lattice constant to that of the layer deposited. If the lattice constant of the substrate is substantially different from that of the deposited material, there will be a dewetting effect where the material can form quantum dots.
* Chemical vapor deposition (CVD): Volatile precursors are introduced in gas phase in a low-pressure reactor chamber. Argon or nitrogen gas are usually used as carrier gas to dilute the precursor and achieve optimal pressure and concentration. The substrate is heated, and the precursor decomposes at the surface. There are several different types of CVD reactors, such as cold wall and hot wall reactors. There are also plasma enhanced reactors (PECVD) where the electric field in the plasma can force growth of nanowires in the direction of the electric field.

====Lbl self-limiting reactions====
* Atomic layer deposition: Similar to CVD, but usually carried out in solution.
* Iterative saturating reactions. ALD is a self-limiting process where only one layer at a time is deposited. When the first layer is deposited it needs to be reactivated in order to grow a second layer. It is therefore easy to kontroll thickness.

=== Kapittel 4: Nanocontact printing and writing ===

====Soft lithography and microcontact printing ====
* Sub 100 nm Soft Lithography: Previous chapters has covered printing on 10.000-100 nm scale. Need for further miniaturization because of demand for more power, efficiency, and density. This can be done by manipulating PDMS stamp, Dip Pen Nanolithography (DPN), Whittling Nanostructures or by Nanoplotters

====Manipulating PDMS stamp====
* Manipulating PDMS stamp can be done in various ways, and seven of the basic ideas will now be explained. Illustrating pictures are in the book and in foils.
# Compress the stamp, mold to get a new stamp with inverse pattern, peel off and repeat.
# Apply force perpendicular onto stamp when on substrate. The areas in contact with substrate will then increase, and spaces in between gets smaller.
# Size reduction by reactive spreading of ink when in contact with substrate. The contact time + properties of the ink decide to which degree the ink spreads. The printed area is increased and the spacing between is reduced.
# Size reduction by extraction of inert filler (just like removing water from a sponge).
# Size reduction by swelling the stamp in toluene. The areas in contact with the surface are increased in size while the spacing between is reduced.
# Size reduction by stretching stamp so that dimensions get smaller in one direction and larger in another.
# Size reduction by double-printing.
* Overpressure printing
**Defect-free contact printing is restricted to a certain range of height-to-width ratios. If ratio is outside 0,2-2, the roof of the grooves on stamp will touch the substrate. Too high perpendicular force on stamp has the same effect, but overpressure can also be used to form new patterns such as micron scale discs and rings of ferromagnetic core-shell nanoparticles. Nanoparticles are then transferred to PDMS stamp by Langmuir-Blodgett technique (chapter 6) and then into contact with Au-coated silicon substrate. Low pressure => discs, high pressure => rings.
*Limitations
** Deformation can be a shortcoming if care is not taken with the dimensions of surface relief pattern in the stamp as this can give unwanted deformations. Quality of printed pattern will not be good.

====Dip pen nanolithography====
* Alkanethiols can be written on gold substrate with AFM tip. The alkanethiols are delivered to the tip via a water meniscus, and this can be adapted to suit other surface chemistries. The result is 10 nm fine patterns of molecules (biomolecules, polymers etc.) on metals, semiconductors and dielectrics.
* Sol-gel DPN: patterning of solid-state materials. Nanoscale patterns are written using a metal oxide sol-gel precursor in a solvent carrier. The sol-gel precursors are hydrolyzed to metal oxide by use of atmospheric moisture and water meniscus at the tip-substrate interface. pH, substrate temperature and post treatment can be varied.
*Enzyme DPN: A scanning microscope tip can be used to place an enzyme on a specific site on a biomolecule with nanometer presicion. This method leads to the possibility of bionanodegradable electronic and optical devices.
*Electrostatic DPN: Like thin films can be made of charged polyelectrolytes, an AFM tip can "draw" lines or structures of charged polymers with for example specific electrical properties to build nanoscale electronic devices.
*Electrochemical DPN: The meniscus that forms between surface and tip is used as a nanochemical reactor. Electrochemical deposition can be done by applying voltage between tip and substrate. Ex: making platinum lines can be done by reducing Pt salt at -4 V, and silica lines can be made by oxidation of a silicon surface at +10 V.

====Whittling of nanostructures (section 4.19)====
* Only be able to explain basic principle
**The spatial extent of SAMs can be reduced by so-called "whittling". Whittling is an electrochemical desorption process where a voltage applied will cause ligands to desorb. It has been found that the larger the accessibility of a molecule, the lower the desorbation voltage is (fig. 4.22)

====Nanoplotters and nanoblotters====
* What are these and what can they be used for?
**Nanoplotter: Parallel cantilevers write SAM nanopatterns simultaneously.
**Nanoblotters: An PDMS inkwell has been created to deliver ink to the nanoplotter cantilever tips (fig. 4.26)

====Combinatorial libraries====
* Be able to explain the basic principle and how it is used to find new and improved materials.
**DPN can be used to put different materials together in the research of new material composition. With DPN, many different combinations can be made with small material amounts used.

=== Kapittel 5: Nano-rod, nanotube, nanowire self-assembly ===

''Emily skriver på denne. Håper folk retter opp dersom de finner feil, og legg gjerne til flere ting:)''

====Templating nanowires and nanorods====
Templates can be used for making solid nanorods and nanotubes of controlled sizes. Examples of templates are alumina, silicon, zeolites and lipid bilayers.

====Making modulated diameter silicon templates====
A p-doped silicon wafer is put in aqueous HF and an oxidizing potential is applied. The result from this is nanoporous silicon with a random network of pores. The diameter of the pores can be tuned by controlling the voltage or current. The higher the current is, the wider the channels get. If the current is modulated during oxidation, the resulting structure is an array of modulated diameter nanochannels. If perfectly ordered pores are desired, the wafer can be lithographically patterned with regular array of nanowells in advance. The electric field will then be focused at the tip of these wells.

====Making porous alumina membranes====
Porous alumina membranes can be made by anodic oxidation of lithograpically embossed aluminum sheet in phosphoric or oxalic acid electrolyte (the almunium sheet functions as the anode).

<math> 2Al + 3PO_4^{3-} \rightarrow Al_2O_3 + 3PO_3^{3-}</math>

The residual Al and <math>Al_2O_3</math> is removed by mercuric chloride and phosphoric acid. The diameter is controlled and can be 20-500nm. Mechanisms that give ordered channels are the fact that electric fields created by applied voltage repell each other, and that we have volume expansion when aluminum becomes alumina. Temperature is also a factor that affects the reaction.
In this process oxygen diffuses through the alumina layer from the electrolyte and alumina grows at the alumina/aluminum interface, while alumina is slowly dissolved at the alumina/electrolyte interface. This growth/dissolution comes to an equilibrium at the bottom of the pore, giving a specific thickness for a certain current/voltage. The growth of alumina is still allowed to continue upwards (along the pore walls) where the electric field is weaker, giving longer pores. Growth continues until the electric field is quenced or there is no more aluminum left.

====Modulated diameter gold nanorods====
With use of silicon template. The back surface of the silicon membrane is subjected to a local thermal oxidation which formes silica. The silica is then removed by HF. By proceeding with a KOH anisotropic etch on the same area, and a dip in HF, the pores in the template are opened. A gold sputter deposition can then be done on the backside. This gold layer acts as a catalyst for continued electroless deposition of gold. Finally, the silicon membrane is etched away, and the gold nanorod dispersion can be collected.

====Modulated composition nanorods/nanobarcodes====
Modulated composition nanorods can be made by electrochemical deposition of different metal segments within the channels of an alumina template (electrodeposition will be better explained in the following section). Any type of material that can be electrodeposited can be used in the nanobarcodes. One synthesis route is to evaporate thin metal film to one side of an alumina membrane. This metal film function as the cathode, and metal deposition begins at the bottom. Bath can be switched between different metal salts to grow several segments. The alumina membrane is dissolved using sodium hydroxide, and the metal backing is dissolved using acid.

Nanobarcodes can be used to tag molecules in analytical chemistry and biology. Characteristic of metals are optical reflectivity, which means that different segments of the barcode nanorod can be distinguished in optical microscopy. Probe molecules must be anchored to different segments, and the rods must be dispersed in analyte containing target molecules which bear a luminescent label. By molecular recognition, the target molecules bind to the probe molecules (ex: ligand-receptor binding for biological applications). By looking at the segments that light up, it can be decided which molecules excist in the solution.

====Electroplating/electrodeposition====
The part to be plated is the cathode, while the anode is made of the material to be plated. Both components are immersed in electrolyte solution. The dissolved metal ions (cations) are reduced at the interface between the solution and the cathode when current is applied.

====Electroless deposition====
This is an auto-catalytic plating method that involves several simultaneous reactions in an aqueous solution. The reaction involves plating of a metal onto a conductive surface and occurs without the use of external electrical power. This is accomplished when hydrogen is released by a reducing agent and thus producing a negative charge on the surface of the metal. There is no direct controll over length or thickness of the deposited layer. This needs to be calibrated with regards to concentration of precursor and amount of time that reaction is allowed to run.

====Nanotubes====
Nanotubes can be made by partial filling of the membranes radially. This means that a uniform coating must be deposited on the pore walls. One way to do this is by letting fluid spontaneously wet inside the template pores. Fluids that can be used are molten polymers, polymer solution or sol-gel preparation. These are coated onto template using capillary forces resulting from small diameter channels with a large available surface. Solidification of these fluids can be done by heating, cooling, waiting or using a catalyst. With this method it is difficult to control the wall thickness.
Another way to make nanotubes is by using LbL growth procedure inside the pores. This can be done by CVD of gas phase species, solution phase ALD or LbL electrostatic assembly. Wall thickness is easier to control with these methods.
Finally, the membrane is dissolved. It can also be deposited other material inside the remaining void to get coaxially coated rod or wire.

Nanotubes can also be made from LbL electrostatic coating of nanorods. The rods can be dissolved afterwards, and will leave a closed-ended tube. This method is applicable to any material that can be coated onto a nanorod and not be affected by the etching step.

====Magnetic Nanorods====
Magnetic metals such as iron, cobalt or nickel can easily be deposited into membranes. Magnetic properties are direction and size dependent. If the thickness of the magnetic segments on a nanorod is smaller than the diameter, they will self assemble into 3D bundles. If the thickness is bigger than the diameter, they will align in chains of rods. If the thickness is the same as the diameter they will be in random aggregates. Magnetic nanorods can be used for separation of molecules. A tri-segmented Au-Ni-Au nanorods can be used as affinity template for histidine- tagged proteins. Nickel selectively captures the labeled protein, and a magnetic field can be used to separate the rod with the captured protein from the rest of the solution of biomolecules. After this, the proteins can be chemically released from the magnetic nanorod. The gold segments must be in the rod to protect nickel from the etching during dissolution of alumina template after electrodeposition, and also to prevent aggregation.

====Making Single Crystal Nanowires====
Single crystal nanowires can be made by Vapor-Liquid-Solid (VLS) synthesis, Supercritical Fluid-Liquid-Solid (SFLS) synthesis or by Pulsed laser deposition.

*VLS Synthesis
A catalyst droplet first melts, then becomes saturated with precursors. Elements extrude out of the catalyst droplet as a single crystal nanowire in a furnace where the temperature is controlled to maintain liquid state of the catalyst droplet. Micrometer length with diameter less than 10 nm can be done. The diameter is controlled by the diameter of the catalyst droplet, and growth stops when the nanowire pass out of the hot zone, if the precursor is depleted or the catalyst droplet no longer is in liquid state. One example is to use laser ablation of Fe-Si target to create a Fe-Si nanocluster catalyst droplet. The Si nanowire grow with the (111) lattice planes perpendicular to the growth axis due to epitaxy at the nanocluster-nanowire interface. Doping can be done by controlling stoichometry of the target, or by introducing dopant into gas phase during growth.

*SFLS Synthesis
Similar to VLS, but used for high-eutectic temperature combinations. The solvent is pressurized above its critical point to reach higher temperatures. Can be applied to semiconductor/metal combinations (Ga/GaAs, In/InN) with eutectic temperature below 600 degrees. Au is used as catalytic seed, and diameter depends on this.

*Pulsed laser deposition
A pulsed laser is used to ablate a target (pulsed laser ablation), meaning that the pulsed laser vaporizes small parts of the target for each pulse. This creates a plume of vaporized precursor material which is allowed to deposit onto a substrate that is placed in the reaction chamber. When small catalyst particles are placed on the substrate, small single crystal nanowires can be grown. The diameter of the nanowires are determined by the size of the catalyst particles.

====Nanowires branch out====
Can create branched nanowires by VLS growth. The catalytic nanoclusters from solution placed on specific point on the body of a parent nanowire before growth. The process can be repeated for a hyper-branched construction. This could be the future development of nanowire electronics in 3D.

====Quantum Size Effects (QSE)====
QSE appear when the particle size becomes smaller than the exciton size for the material (about 5 nm for silicon). Exciton is a bound state of an electron and an electron hole in an insulator or semiconductor, which is defined by the energy gap between the valence band and the conduction band. Color of the emitted light is determined by the size of gap energy. Gap energy increases with decreasing nanowire diameter. This can be used for LEDs and lasers. Both quantum confined nanoclusters and nanowires show QSE, but anisotropy make them different. Luminescent nanocluster emits plane-polarized light, while nanorod exhibits linearly polarized light.

====Alignment methods====
Alignment methods include electric field based alignment, microfluidic alignment and Langmuir-Blodgett technique.

*Electric Field Based Alignment
Apply voltage between two micropatterned electrodes to produce electric field. Charges within a nanowire in solution become polarized, creating an attraction between the electrodes and the nanowire. The electric field is quenched when the gap between the electrodes are bridged by a nanowire. This eliminates absorption of a second nanowire at the same electrodes. Metal spots can be evaporated onto insulator surface to focus the electric field.

*Microfluidic Alignment
A PDMS stamp with a series of parallel rectangular grooves is used for this purpose. The channels are aligned under a microscope with electrodes that have been previously patterned on a substrate (these will function as metal contacts for the conducting or semiconducting lines made by this method). A drop of nanowire suspension is flowed into the microchannels by capillary forces, and solvent evaporation aligns the wires at the edges of the channels.

*Langmuir-Blodgett Technique
A Langmuir film is first created when a small amount of insoluble liquid (amphiphile) is poured onto another liquid. The balance of surface tension forces determines the profile of the meniscus formed when a substrate is pushed into this liquid. If the substrate is hydrophobic it will experience deposition of the amphiphiles during immersion. If it is hydrophilic it will experience deposition during retraction. A nanowire array can be made by firstly compressing the interface to increase the surface density of nanowires (so they align parallel to each other), and then do a double dip. The second dip must be done so that the wires align normal to the previous once.

Application areas for these methods are in LED’s, transistors and in nanowire UV photodetectors.

====LED====
A LED can be made by assembling an n-doped and a p-doped semiconductor nanowire perpendicular to each other. This is done by [[TMT4320_-_Nanomaterialer#Alignment_methods|electric field based alignment]] with two electrode pairs aligned perpendicular to each other where voltage is applied to one pair at a time. They can also be assembled by using the microfluidic approach. When a potential is applied across the junction, light is emitted when electrons recombine with holes at the junction between the differently doped wires. Color of the emitted light depends on composition and condition of semiconducting material used. The LED can only conduct current in one direction. With positive voltage current flows. With negative voltage current is inhibited. The key for success is to achieve abrupt and uncontaminated junction between n and p doped wire. Efficiency can be improved by using core-shell-shell nanowire axial heterostructure. The greatest challenge is to make arrays of closely spaced junctions because the nanowires are so thin. This leads to the pitch problem, how to pack light sources into smallest possible area.

====Transistors====
A transistor can switch or amplify signals, and has three terminals (n-p-n). The n-type region attached to the negative end of the battery sends electrons into p-region, and the n-type region attached to the positive end slows the electrons down. The p-type region in the middle does both. Because of this, a depletion layer develops between the base and the emitter, and the base and the collector. The thickness of the layer is varied by the potential in each region. Active bipolar n-p-n transistor can be built from heavy and lightly n-doped nanowires crossing a common p-type wire base.

====How can nanowire transistors be used as sensors?====
Si nanowires are naturally coated with silica through VLS synthesis. This makes it easy for surface silanol groups to attach to the wire. If probe molecules are anchored to the surface silanols, highly sensitive real time electrically based sensors can be made. Low levels of chemical and biological species can be detected. Boron doped silicon nanowire is used as a FET. The wire is self assembled across electrodes (source and drain), and aminoethylsilane anchored to SiOH surface groups. The conductance of the wire changes with pH linearly due to protonation or deprotonation of the amine. An increase of the surface negative charge (deprotonation) attracts additional holes into the p-channel and the conductance is enhanced. The reverse action at low pH, an increase of surface positive charge causes protonation which repell holes from the channel. The conductance is decreased. Almost any type of molecule can be anchored to silica, so sensors can be designed to detect almost anything. For example, a biotin could be strapped to the surface amine groups to detect streptavidin.

====Nanowire UV photodetector====
The conductivity of ZnO nanowires is extremely sensitive to ultraviolet light exposure, which means that UV light can switch the nanowires between ON and OFF states. ZnO nanowires are highly insulating in the dark, but UV light with wavelength less than 380 nm decreases resistivity by 4 to 6 orders of magnitude. These nanowire photoconductors exhibit excellent wavelength selectivity. Green light (532nm) gives no response, while less intense UV light increases conductivity 4 orders. The response cut-off wavelength is at about 370 nm.

====Simplifying complex nanowires====
Complex oxides with superconducting, ferroelectric and ferromagnetic properties can not easily be made as nanowires by conventional methods. MgO nanowires must be used as templates. Firstly, single crystal orthogonal MgO nanowires are grown on single crystal MgO substrate. Oxygen is flowed over <math>Mg_3N_2</math> at 900 degrees as precursor for VLS, using Au catalyst. After the MgO nanowires have been made, the complex metal oxide is deposited by pulsed laser deposition to create a shell on the surface of MgO wires. Another approach to simplify complex nanowires is to use hydrothermal synthesis. This can be used to make <math>PbTiO_3</math> nanorods which is a ferroelectric material and potentially useful as building blocks in nanoelectrochemical systems. (Amorphous <math>PbTiO_{(3-X)}OH_{2X}</math> (mulig jeg rettet feil/misforstod?) precursor is mixed with sodium dodecyl benzene sulfonate surfactant and reacted at 48 h at 180 degrees at alkaline conditions in the presence of a substrate.) The nanorods obtained have a squared cross section 35-400 nm, and up to 5 um long. The rods grow in the (001) direction by self-assembly of nanocubes to anisotropic mesocrystals, which is ripened into nanorods.

====Electrospinning====
Electrospinning is nanofiber extrusion in a capillary jet. A polymer solution or polymer sol-gel pass through a high voltage metal capillary to create a thin charged stream. The stream undergoes stretching, bending and solvent evaporation. The charged nanofibers are driven to ground electrodes. The dimensions of the fibers depend on solvent viscosity, conductivity, surface tension and precursor concentration. The collector electrodes can be patterned to make organized arrays between them by electrostatic self assembly. The electrodes can be grounded simultaneously or sequentially. This can be used to make single layer or multilayer nanowire architectures.

====Hollow nanofibers by electrospinning====
Hollow nanofibers can be made by co-axial double capillary electrospinning that creates heavy mineral oil core with inorganic polymer around (Ti and PVP). The core-shell nanofibers are collected on an aluminum or silicon substrate and hydrolyzed. The oily core can be extracted with octane, which creates nanotubes with amorphous <math>TiO_2</math> + PVP. To crystallize <math>TiO_2</math> and oxidate PVP, the tubes can be calcined in air at 500 degrees.

====Dual electrospinning====
A side by side spinneret can be used to make bicomponent fibers. Ex: two solutions containing <math>TiO_2</math>/<math>SnO_2</math> are simultaneously jetted. This is calcined. A heterojunction of <math>SnO_2</math>/<math>TiO_2</math> can create devices with extremely high quantum efficiency and photocatalytic activity for treatment of organic pollutants in water and air.

====Dette mangler:====
* Carbon nanotubes (sections 5.41, 5.42, 5.44, 5.45-5.48 and lecture notes)
** What are carbon nanotubes? Be able to describe the three different structures they can have and how their properties are different.
** Be able to describe briefly (basic principles) at least two of the three main methods used to synthesize carbon nanotubes
*** Arc discharge
*** Laser ablation
*** CVD
** How can the different structure nanotubes be separated from each other and from other carbon particles.
** Be able to say something about their properties
*** Mechanical
*** Electrical
*** Chemical
** Know some about carbon nanotube chemistry (reactivity on the surface vs the ends etc.)
** Aligning of carbon nanotubes
*** Evaporation induced self-assembly
*** Patterned hydrophilic SAM on substrate – carbon nanotubes will assemble only on the hydrophilic patches.
*** Alignment by pre-existing patterns
**** Perpendicular to substrate
**** Parallel to substrate
*** AC/DC electric fields
** Applications of carbon nanotubes
*** Sensors
*** Strengthening of materials (composites)
*** Added to materials to improve conductivity

=== Kapittel 6: Nanocluster Self-Assembly ===

====Capped nanoclusters====

A capped nanocluster is a nanometer scale particle with well-defined positions of the constituent atoms. They nucleate from atoms and enter a size range where they behave electronically as molecular nanoclusters. As the number of atoms increases further, they cross over into the nanoscale size domain where quantum size effects dominate, they become quantum dots. A capped nanocluster has a monolayer of a capping ligand on the surface, which can be a polymer or an alkane thiol (if the surface is silver or gold) or some other molecule with an end group that will bind to the surface of the nanocluster. The capping molecules will prevent further growth of the nanocluster. Capping groups serve multiple purposes:
*Change solubility properties
*Enable size-selective crystallization
*Surface functionalization
*Protect nanoclusters from luminescence or charge-carrier quenching

====General principles for synthesis of capped nanoclusters (arrested nucleation and growth)====

One general synthesis method is the arrested nucleation and growth synthesis. The basic idea is to rapidly create a large number of nucleated seeds (of desired materials) and then allow these to grow at the same rate below supersaturation conditions. This method can be described by the following steps:
* Desired precursors are added to a solution containing a proper capping agent, which is held at an intermediate temperature (200-400 °C depending on the materials. Temperature needs to be high enough to overcome the activation energy for the reaction.).
* Precursors need to be added at an amount that is over the saturation point for the materials in that specific solution.
* Materials will rapidly nucleate (precipitate) and start growing. Once the first molecules have reacted and created a small seed, the energy required for further growth is smaller than the initial activation energy. The nucleated seed can therefore continue to grow below the saturation concentration for the precursor materials.
* Once the nanoclusters reach a certain size range, which may vary from one material to the other, the capping agents will adsorb on the surface of the nanoclusters and prevent further growth. The nanoclusters that are formed will not all have the same diameter, but a range of different diameter clusters will be formed. This can be due to for example concentration gradients in the reactor or reaction medium.

====Minimize size dispersity by confining the reaction space====

The size of the capped nanoclusters can be controlled by growing them in nanowells made by the methode in figure x. The nanowells are obtained by patterning a silicon wafer with a layer of well-ordered microspheres. By pressing the microspheres against a the wafer and at the same time melt the surface of the wafer with a pulsed laser molten silicon will flow into the voids between the spheres. The size of the nanowells depend on the size of the spheres, the energy density of the laser pulse and applied mechanical pressure, while the size of the crystals depend on the well volume and concentration of the reactants. The crystals can be removed by ultrasound. The downside of the approach is that the amount of nanocrystals obtained will be quiet small.

====Tuning properties through physical dimensions rather than chemical composition (QSE)====

When electrons are confined in space the size invariant continuum of electronic states of bulk matter transformes into size dependent discrete electronic states in a quantum dot. At the 1-5 nm length scale, which is the CdSe nanocluster size range, the parent continuous electron bands of the bulk semiconductor becomes discrete. The nanoclusters then belong to the quantum size regime, and the properties begin to scale in a predictable fashion with size. By looking at the Schrödinger wave equation it can be seen that there is a blue quantum size effect shift in the energy of the first exciton band or band gap that scales with the reciprocal of the square of the radius of the nanocluster. The wavelengths absorbed change, and the colors of the nanoclusters can be alterd from yellow to red, by changing the physical size of the clusters

====How can different phases occur for smaller size particles?====

Similar to temperature and pressure, phase transformations in bulk materials are dependent on size. Phase transitions that are prohibited or slowed down by activation energies in the bulk can occur much more readily in nanocrystals of same material. Because of the small size of the crystal the influence of bulk and surface-free energies are different from in a bulk matter. Phase transformations show a distinct dependence on nanocrystal size. It can be shown that phase of nanoclusters can change just by exposing them to a different chemical environment at room temperature.

====Makeing nanoclusters water soluble====

Why? Water is cheap, widely available and use of it avoides the disposal o organic solvents, which can be quiet harmful for the environment. (Green chemistry). You can use the same principles as for the SAM surface chemistry. A hydrophilic SAM is made by choosing a hydrophilic group such as a carboxylate, ammonium or oligo ethylene glycol. In the case of a gold nanocluster, a thiol with a terminal carboxyl group gives an ionized, water loving carboxylate when in aqueous solution. Hydrophobic nanoclusters can be wrapped by amphiphilic polyers. The polymer coating is stabilized by partially cross linking the anhydride gropuos with bis(6-aminohexyl)amine. Can also coat with silica. Often, the resulting crystals bear a surface charge, which allows their use in electrostatic layer-by-layer deposition.

====Separation of nanoclusters by size using using a non-solvent and centrifugation====

Nanoclusters can be dissolved in toluene and by gradually adding a non-solvent (e.g. acetone) the nanoclusters will precipitate. The largest clusters precipitate first. Every time a bit of acetone is added the solution is centrifuged and the precipitate collected. The result is highly monodisperse nanoclusters collected in each fraction.

====Superlattice====

A superlattice is a material with periodically alternating layers of several substances. Such structures possess periodicity both on the scale of each layer's crystal lattice and on the scale of the alternating layers.

====Assembling of superlattices====

A superlattice can be assembled by means of these techniques:
*Tri-layer solvent diffusion crystallization - Three immiscible solvents are arranged to form separate layers in a test tube. Bottom layer →capped CdSe nanoclusters dissolved in toluene. Middle layer →buffer layer of 2-propanol selected for poor solvent properties wrt the nanoclusters. Top layer →non-solvent for the nanoclusters such as methanol. The process involves slow diffusion of the nanoclusters from the toluene bottom layer and the methanol from the top layer into the buffer layer. The change in solvent properties causes a slow and controlled nucleation and growth of capped CdSe nanocluster crystals.
*Sedimentation –
*Evaporation induced self-assembly – Strong capillary forces in an evaporating water meniscus drives the nanocomponents into close-packing.
*Langmuir-Blodgett – A dilute monolayer of capped silver nanoclusters is spread on an air-water interface. Using Langmuir – Blodgett “equipment”, this monolayer can gradually be compressed until a compact monolayer is formed.

====Gjenstår====

*Why do we want to make superlattices? (change of properties, properties of superlattice does not necessarily equal the sum of the properties of the individual constituents)How can capping agents (different type and length) affect the properties of a superstructure? (section 6.15)Alloying core-shell nanoclusters

* Nanocluster-polymer composites
** What is it?
** How can it be used for down-conversion of light?
* Be able to give one or two examples of how different size nanoclusters labeled with different fluorescent molecules can be used in biology.
* What is a tetrapod and what is the main priciples of the synthesis behind the tetrapod?
** Using a material that has two common crystal polymorphs where growth of one over the other can be controlled by synthesis temperature.
** Use of a long chain molecule which selectively binds to specific facets of the structure and hinders growth in those directions. This confines the growth of the material to one spatial dimension.
* Photochromic metal nanoclusters (section 6.31)
** Be able to explain what happens to silver nanoclusters embedded in a titania matrix when it is exposed to either UV-light or visible light.
* What is a buckyball and what can it be used for? What special properties does it exhibit? (Do not need to know specific details of synthesis or assembly techniques.)

=== Kapittel 7: Microspheres – Colors from the Beaker ===

Nå ferdig med så mye som forfatteren greide, men finn gjerne ut resten og del det med alle!

====What is a photonic crystal (PC)? ====
*It is a crystal consisting of a material with high dielectric contrast and periodicity at the light scale
*Wavelengths of light that are allowed to travel are known as modes, and groups of allowed modes form bands. Disallowed bands of wavelengths are called photonic band gaps (PBG).
*Vullums definition: Natural gratings that diffract light are based on dielectric lattices with periodicity at optical wavelengths. 3D optical diffraction gratings have dielectric lattices that are geometrically complimentary.
*1D PC (planes) is a crystal which only inhibit light to travel in one direction
*2D PC (rods) inhibits light to travel in two directions
*3D PC (spheres) inhibits litght to travel in any direction and has a full photonic band gap, whilst 1D and 2D only have so called stopgaps

====Photonic Crystal defects====
*Point defects: Holes, missing spheres, in a 3D PC can trap light inside the crystal
*Line defects: Many holes which make a line can guide light through a crystal
*Plane defects: A missing plane or a defect in a plane can make photons slip through to the other side. Planes consisting of another type of material can cause the perfect reflection curve of a PBG-crystal to drop at certain wavelengths depending on the size of the defect.

====Making defects====
*Writing defects: Multiphoton laser writing using a confocal optical microscope induced polymerization of an organic monomer in the colloidal crystal to create small line inside the photonic lattice. Then you treat the crystal and remove the polymer. In reversed opal structures you can use laser microwriting where you attach a laser to a scanning optical microscope which again changes the phase (which again changes the refractive index) of the inverse opal by annealing.
*Synthesizing planar defects: Introducing a dense layer or a layer with spheres of a different size than the surrounding colloidal crystal. Dense layers can be introduced by either CVD, electrolyte LbL, PDMS-stamps or maybe another deposition technique. The process consists of growing a photonic crystal, then using electrolyte LbL-deposition or PDMS-stamp make a thin film before making another photonic crystal. It's like a sandwich.

====Manipulating photonic crystals usage====
*Color of the structure is partially determined by the size of its spheres, where small spheres give blue/purple colors and larger spheres goes towards red (from yellow to green and then red).
*Non-close-packed polymerized colloidal crystalline arrays can be made to swell or shrink by external influence. As the diffraction colors of the crystal depend on the spacing between microspheres you can place a hydrogel between the spheres and this gel will swell or shrink depending on external environments. This will make the color change when the gel shrinks or swells as the pH, temperature, water concentration or ionic strength changes.
*The dielectric constant can be changed by changing the material, the structure of the crystal ''or something else that others edit in here''
*An example: Removal of cation causes a hydrogel to shrink, which can be detected at even very small concentrations. The order of cation complexation determines how sensitive the sensor is. Cation selectively binds covalently to the polymer network, sol-gel or hydrogel.

====Core-corona, core-shell-corona and multi-shell microspheres====
Core-corona and core-shell-corona can be made by both re-growth and one stage growth as multishell microspheres probably is better off being made by the re-growth process. The purpose of making these spheres is to put a lot more functionalities into just one sphere. The shells can be fluorescent, magnetic , photoactive, semiconductive, sacrificial or something else pulled out of a hat.

====Growth synthesis====
*One stage: Reagents are mixed and the microspheres are obtained in solution by a nucleation and growth
*Re-growth: First a sees is produced. The seed is then allowed to grow in several steps. Surface tension controls the shape, where low surface tension gives spherical particles.

====Self assembly of photonic crystals====
*Sedimentation (be able to explain in more detail): Use Stokes equation to make the radius as you want it by changing the viscosity very slowly.
*Electrophoresis '''– noen som veit?'''
*Hydrodynamic shear '''– noen som veit?'''
*Spin coating '''– noen som veit?'''
*Langmuir-Blodgett layer-by-layer (be able to explain in more detail) '''– noen som veit?'''
*Parallel plate confinement: Force spheres to assemble by placing them between two parallel plates and slowly moving one plate closer to the other. Important with slow movement to prevent defects. This can be done both dry and in fluid. It is necessary to increase density and viscosity of solvent so that settling occurs slowly in order to control structure and shape, and to avoid defects.
*Evaporation induced self-assembly, EISA (be able to explain in more detail) Capillary forces drive the assembly of spheres in a solution as you remove a wetting plate out of the solution. These the need to be dried and this can cause cracking. Vertical substrate is placed in a dispersion of microspheres. As solvent evaporates, the microspheres are driven by convective forces (forces from movement in solvent towards wall, surface, water meniscus) to the solvent-air meniscus. The layer thickness is determined by the diameter of the microspheres, their volume, concentration and the wetting properties of the solvent on the substrate.

====Colloidal aggregates====
*CA are made either by templated pattern in a surface or by aggregation in a homogeneous emulsion.
Emulsion-way:
*They are disperse microspheres in a solvent such as toulene.
*Add dispersion to solution of surfactant and water
*Stir or shake to get emulsion
*Toulene evapourates and as toulene droplets shrink, microspheres are pulled together in a stable cluster through capillary forces.
Photonic crystal marbles:
*Aqueous dispersion of microspheres is forced, under pressure, through a small syringe in the presence of an electric field. Surface charge on the liquid jet make it break into homogeneously sized spherical particles. Each droplet (sphere) contains a preset quantity of microspheres.
*Electrospraying - '''noen forslag?'''

====Bragg-Snell law====
*The reflected light has a wavelength depending on Bragg's and Snell's law. This then tells us that the wavelength of the first stop band is proportional to distance between the lattice plains. This gives that the longer the distance between the plains (bigger microspheres) gives longer wavelength.
<math>\lambda_{c(hkl)} = 2d_{hkl}\sqrt{\langle \epsilon \rangle - sin^2{\theta}} </math>
der <math>\langle \epsilon \rangle</math> is the effective dielectric constant of the colloidal crystal.

====Cracking====
This happens when the thin hydration layers around the crystal spheres dry out. This creates capillary stress and thermal expansion. To prevent cracking you can dry the crystal slowly, use hydrophobic spheres. Methods for preventing this is:
*<math>SiCl_4</math> reacting within the hydration layer to create a <math>SiO_2</math> layer between the spheres. Rehydrate to form multiple layers. Advantages as good control of layer thickness as it can be controlled/monitores by optical diffraction as a thicker layer res-shifts the diffraction peak.
*Necking at room temperature using vapor phase alternating chemical reactions
*Heat treatment before assembly. This may require pretreatment before assembly to give desired surface charges. Redeisperse and crystallize without volume contraction

====Liquid crystal photonic crystal====
A liquid crystal is neither a liquid nor a crystal, but an intermediate state of matter, so called mesophase. Lacks the long range order of the crystalline state and does not exhibit the randomness of the liquid state.
*Themotropics are liquid crystals which consists of melted anisotropical shapes (rods or discs) where they ar partially alligned. The order of the components in the liquid crystal is determined and changed bu the temperature.
*Two groups of thermotropics are ''nematic'', where the molecules have no positional order, but they have a long-range orientational order, and ''discotic'', which consists of disc-shaped particles that can orient in a layer-like fashion.
*By applying electric- and/or magnetic fields the small crystals in the liquid will align after the applied fields and this can control the refractive index of the film or whatever you have made out of this liquid crystal. Electric/magnetic fields or temperature changes can make it go from nearly transparent to reflective. Eksample of usage is privacy/smart windows.
*By filling the voids in an inverse opal photonic crystal with liquid crystal we make what's called a Liquid Crystal Photonic Crystal. (LCPC) Applying a field or changing the temperature makes the refractive index of the liquid crystal inside the voids change. This means that other wavelengths will satisfy Bragg's criterion, which in practice means that the color of the LCPC changes (you alter the stop band frequency) See [[TMT4320_-_Nanomaterialer#Bragg-Snell_law | Bragg-Snell law]].
*LCPC is thought to be used as tunable photonic crystal device and liquid crystal-colloidal crystal switch.

=== Reactions that you need to know: ===
* Reaction of alkane thiolate with gold. Important to know that alkane thiols have a specific affinity for gold (also keep in mind that silver and gold have very similar properties).
* Reaction that occurs when during anodic oxidation of Al to produce porous alumina membranes.
* Reaction that occurs when silica microspheres are formed from Si(OEt)4 and water (section 7.9): <math>Si(OEt)_4 + 2H_2O \rightarrow SiO_2 + 4EtOH</math>

== Eksterne linker ==
*[http://www.ntnu.no/portal/page/portal/ntnuno/AlleEmner?rootItemId=22934&selectedItemId=31007&emnekode=TMT4320 NTNUs fagbeskrivelse]
*[http://www.ntnu.no/studieinformasjon/timeplan/h08/?emnekode=TMT4320-1&valg=emnekode&bokst= Timeplan Høst08]

[[Kategori:Obligatoriske emner]]
[[Kategori:Fag 5. semester]]
[[Kategori:Fag]]

TMT4320 - Nanomaterialer

2008-12-15T16:52:34Z

Audunnys: /* LED */

{{Infobox
|Fakta høst 2008
|*Foreleser: Fride Vullum
*Stud-ass: Katja Ekroll Jahren og Ørjan Fossmark Lohne
*Vurderingsform: Skriftlig eksamen
*Eksamensdato: 18. desember
}}

{{Infobox
|Øvingsopplegg høst 2008
|* Antall godkjente: 6/12
* Innleveringssted: Utenfor R7
* Frist: Tirsdager 16:00 (?)
}}

Emnet skal gi en innføring i grunnleggende kjemisk prinsipper for å lage nanomaterialer. Stikkord: "Self-assembled" monolag ([[SAM]]) og hvordan disse kan formes ved myk litografi og "dip pen" nanolitografi, syntese av tredimensjonale multilag strukturer. Tynne filmer ved kjemisk gassfase deponering. Syntese av nanopartikler, nanostaver, nanorør og nanoledninger. Våtkjemiske syntese av oksidbaserte nanomaterialer. "Self-asembly" av kolloidale mikrokuler til fotoniske krystaller, porøse nanomaterialer, blokk-kopolymere som nanomaterialer. "Self assembly" av store byggeblokker til funksjonelle anordninger.

== Oppsummering av pensum ==
Her vil det etterhvert vokse fram et lite kompendium i faget. Dette følger i utgangspunktet pensumlista som gjelder for høsten 2008.

===Chapter 1: Nanochemistry Basics ===
Not terribly important.

===Chapter 2: Soft Lithography===
====Self-assembled monolayers (SAMs)====
*The typical example of a SAM is a layer of alkanethiols on a gold substrate.
*The S-H bond is cleaved by oxidation on the gold surface and a covalent Au-S covalent bond is formed.
*The alkanethiols are tilted off-axis from the normal. The angle depends on the surface. (30 ° for a {111} gold surface, 10 ° for a silver surface).
*The end group on the alkanethiols can be tailored to achieve different monolayer properties, thus modifying the surface properties of the structure.

====PDMS stamp====
* PDMS (PolyDiMethylSiloxane) is a soft elastic polymer.
* A master (casting) of the stamp, with the desired pattern, is made with electron or UV-lithography. The master is silanized and made hydrophobic so removing of the stamp becomes easier.
* Liquid PDMS is then poured into the master, after which it is cured and a finished PDMS stamp is removed from the master.
* The critical dimensions of the stamp are limited by the lithography techniques used, and for [[photolithography]] the wavelengths of the light used to expose the [[photoresist]] limits the dimensions. Typical CDs given are, for lateral dimensions within the range of 500nm-200µm, and for the height of patterns 200nm-20µm.
* The PDMS stamp can be dipped in alkanethiol solutions (or solutions of other molecules, collectively known as "chemical ink") and be stamped onto surfaces.
* PDMS stamps work on both planar and curved surfaces.
* For the stamp to properly print a pattern onto a surface, the molecules need to adhere to the stamp from the solution, but the affinity for binding to the surface has to be stronger.

====Hydrophilic / Hydrophobic stamps====
* The endgroup/terminal group on the alkanethiols (or other molecules used) determine the properties of the monolayer, f. ex. a OH-terminal group makes the monolayer hydrophilic, while a <math>CH_3</math>-group makes it hydrophobic.
* Wetability is determined by the polarity of the endgroups.
* By introducing a wetability gradient or abrupt changes in wetability, different effects can be obtained:
** Square drops, by having checkerboard square patterns of hydrophilic monolayers with hydrophobic lines inbetween, and condensating water onto the surface. This is called condensation figures and results from the condensation on the hydrophilic areas, when the substrate is cooled below the dew point. The diffraction pattern of the structure can be studied for obtaining information on the kinetics and structure of the water droplets. This can be used in biological sensing.
** Droplets "running uphill" by having wetability gradients. The droplets are moving towards the more hydrophilic areas, against the force of gravity.
** Nanoring arrays can be synthesized using the condensation figures as templates for molding. A solvent precursor which wets the regions between the microdroplets is added and then evaporated. Deposition of precursor occurs around the perimeter of the droplets. Finally, the water droplets is evaporated, and the precursor remains on the substrate as nanorings.
** Solid state patterning by dipping a SAM-patterned substrate in a precursor solution. This creates microdroplets with a predetermined precursor concentration, which on evaporation and vertical drying leaves behind an array of size-tunable solid precursor dots.

====Printing thin films====
* As long as the adhesion between the chemical ink and the substrate is stronger than the adhesion between the ink and the stamp, printing thin films is no problem
* Metal thin films can be evaporated onto a PDMS stamp (f. ex. gold). Evaporation gives homogenous and directional coatings, and no covering of the side walls on the stamp. This pattern is printed onto a SAM-primed substrate with exposed thiol groups (gold adheres strongly to the metal layer).
* This is a very gentle technique for metal film depositing, good for making contacts on fragile layers. Also good for making 3D stuctures by printing multiple layers. Also, there is no need for photoresist because the pattern is printed directly.

====Electrically contacting SAMs====
* Molecular electronic devices need to make good electrical contact with SAMs.
* Making electrical contacts by vapor deposition on the SAMs may sometimes be more convenient than thin-film printing with a PDMS stamp.
* Other, less gentle methods of metal deposition than printing with PDMS stamps (sputtering, CVD, etc) can cause the metal layer to penetrate the SAM and deposit on the substrate, or even diffuse into the substrate, introducing defects to the structure.
* Morale: Use stamps to deposit metals on SAMs!

====Patterning by photocatalysis====
* Photocatalysis is used to remove parts of a SAM (making patterns)
* Titania (<math>TiO_2</math>) can photocatalytically decompose organic molecules.
* A quartz slide patterned with titanium dioxide in the required pattern using ALD is pressed against a wafer with the SAM on it.
* The assembly is exposed to UV radiation, triggering the degradation of the (organic) SAM. When titania is exposed to UV, radiation free radicals are created, which react with the organic molecues, removing the parts of the SAM that is in contact with the titania. Thus, the substrate in these areas is revealed.

===Kapittel 3: Building layer-by-layer===

====Electrostatic superlattices====
* LbL multilayer films formed by alternate immersion in suspensions of opposite charges.
* A primer layer with a charge adheres to the substrate. The substrate is then dipped in a solution of polyelectrolytes of opposite charge from the primer layer. This process can be repeated numerous times in order to get the desired thickness or functionality of the film.
* As the amount and identity of constituents of each layer can be controlled, a composition gradient can easily be constructed throughout the structure.
* Any species bearing multiple ionic charges can be layered.
* Can be applied to curved surfaces like microspheres, enables applications like hollow spheres with a semipermeable cap.

====Some applications====
* Electrochromic layers (change color when a potential is applied), used in "smart windows" for instance
* Construction of cantilevers for AFMs and similar equipment, using photolithography and LbL

====Analysis, measuring film thickness====
* Optical spectroscopy: If the substrate is transparent, and the film absorbs light at a certain wavelength, the film thickness can be found by monitoring the optical absorption as a function of number of layers. A dye can be introduced to ensure absorption. Easy to perform but hard to interpret - must know the observation area and extinction coefficient of the absorbing group.
* Ellipsometry: Film is probed by polarized light, and change in polarization in the reflected light is measured. This can be used to find the refractive index, thickness, roughness and orientation of a thin film. Ellipsometry works with films much thinner than the wavelength of light - down to atomic layers.
* Quartz crystal microbalance (QCM): Quartz (piezoelectric material) in an alternating electric field contracts/expands with a characteristic oscillation frequency. When mass is added to a QCM the frequency decreases, which correlates directly with the amount of mass added. This allows real-time thickness measurements when the density of the material is known. Works well for hard materials like metals and ceramics, but not for viscoelastic materials.
* Direct techniques: Label each layer with heavy metal atoms and image by TEM. Alternately, deposit a thin gold layer on top of the surface and image cross section by TEM.

====Non-electrostatic lbl assembly====
* LbL doesn't need electrostatic bridges - can use hydrogen bonding, ligand-receptor interactions or even covalent bonds.
* Example: DNA (adenine-thymine and guanine-cytosine bridges)
* Hydrogen bonds can be broken again by changing the pH, or can be strengthened by UV irradiation

====Low-pressure layers====
* Molecular beam epitaxy (MBE): Performed in ultrahigh vacuum, sources of constituents (elemental) are heated, and a thin film alloyed from the constituents is deposited. The result is a single crystal film with homogeneous thickness grown epitaxially on the substrate. The substrate should have a similar lattice constant to that of the layer deposited. If the lattice constant of the substrate is substantially different from that of the deposited material, there will be a dewetting effect where the material can form quantum dots.
* Chemical vapor deposition (CVD): Volatile precursors are introduced in gas phase in a low-pressure reactor chamber. Argon or nitrogen gas are usually used as carrier gas to dilute the precursor and achieve optimal pressure and concentration. The substrate is heated, and the precursor decomposes at the surface. There are several different types of CVD reactors, such as cold wall and hot wall reactors. There are also plasma enhanced reactors (PECVD) where the electric field in the plasma can force growth of nanowires in the direction of the electric field.

====Lbl self-limiting reactions====
* Atomic layer deposition: Similar to CVD, but usually carried out in solution.
* Iterative saturating reactions. ALD is a self-limiting process where only one layer at a time is deposited. When the first layer is deposited it needs to be reactivated in order to grow a second layer. It is therefore easy to kontroll thickness.

=== Kapittel 4: Nanocontact printing and writing ===

====Soft lithography and microcontact printing ====
* Sub 100 nm Soft Lithography: Previous chapters has covered printing on 10.000-100 nm scale. Need for further miniaturization because of demand for more power, efficiency, and density. This can be done by manipulating PDMS stamp, Dip Pen Nanolithography (DPN), Whittling Nanostructures or by Nanoplotters

====Manipulating PDMS stamp====
* Manipulating PDMS stamp can be done in various ways, and seven of the basic ideas will now be explained. Illustrating pictures are in the book and in foils.
# Compress the stamp, mold to get a new stamp with inverse pattern, peel off and repeat.
# Apply force perpendicular onto stamp when on substrate. The areas in contact with substrate will then increase, and spaces in between gets smaller.
# Size reduction by reactive spreading of ink when in contact with substrate. The contact time + properties of the ink decide to which degree the ink spreads. The printed area is increased and the spacing between is reduced.
# Size reduction by extraction of inert filler (just like removing water from a sponge).
# Size reduction by swelling the stamp in toluene. The areas in contact with the surface are increased in size while the spacing between is reduced.
# Size reduction by stretching stamp so that dimensions get smaller in one direction and larger in another.
# Size reduction by double-printing.
* Overpressure printing
**Defect-free contact printing is restricted to a certain range of height-to-width ratios. If ratio is outside 0,2-2, the roof of the grooves on stamp will touch the substrate. Too high perpendicular force on stamp has the same effect, but overpressure can also be used to form new patterns such as micron scale discs and rings of ferromagnetic core-shell nanoparticles. Nanoparticles are then transferred to PDMS stamp by Langmuir-Blodgett technique (chapter 6) and then into contact with Au-coated silicon substrate. Low pressure => discs, high pressure => rings.
*Limitations
** Deformation can be a shortcoming if care is not taken with the dimensions of surface relief pattern in the stamp as this can give unwanted deformations. Quality of printed pattern will not be good.

====Dip pen nanolithography====
* Alkanethiols can be written on gold substrate with AFM tip. The alkanethiols are delivered to the tip via a water meniscus, and this can be adapted to suit other surface chemistries. The result is 10 nm fine patterns of molecules (biomolecules, polymers etc.) on metals, semiconductors and dielectrics.
* Sol-gel DPN: patterning of solid-state materials. Nanoscale patterns are written using a metal oxide sol-gel precursor in a solvent carrier. The sol-gel precursors are hydrolyzed to metal oxide by use of atmospheric moisture and water meniscus at the tip-substrate interface. pH, substrate temperature and post treatment can be varied.
*Enzyme DPN: A scanning microscope tip can be used to place an enzyme on a specific site on a biomolecule with nanometer presicion. This method leads to the possibility of bionanodegradable electronic and optical devices.
*Electrostatic DPN: Like thin films can be made of charged polyelectrolytes, an AFM tip can "draw" lines or structures of charged polymers with for example specific electrical properties to build nanoscale electronic devices.
*Electrochemical DPN: The meniscus that forms between surface and tip is used as a nanochemical reactor. Electrochemical deposition can be done by applying voltage between tip and substrate. Ex: making platinum lines can be done by reducing Pt salt at -4 V, and silica lines can be made by oxidation of a silicon surface at +10 V.

====Whittling of nanostructures (section 4.19)====
* Only be able to explain basic principle
**The spatial extent of SAMs can be reduced by so-called "whittling". Whittling is an electrochemical desorption process where a voltage applied will cause ligands to desorb. It has been found that the larger the accessibility of a molecule, the lower the desorbation voltage is (fig. 4.22)

====Nanoplotters and nanoblotters====
* What are these and what can they be used for?
**Nanoplotter: Parallel cantilevers write SAM nanopatterns simultaneously.
**Nanoblotters: An PDMS inkwell has been created to deliver ink to the nanoplotter cantilever tips (fig. 4.26)

====Combinatorial libraries====
* Be able to explain the basic principle and how it is used to find new and improved materials.
**DPN can be used to put different materials together in the research of new material composition. With DPN, many different combinations can be made with small material amounts used.

=== Kapittel 5: Nano-rod, nanotube, nanowire self-assembly ===

''Emily skriver på denne. Håper folk retter opp dersom de finner feil, og legg gjerne til flere ting:)''

====Templating nanowires and nanorods====
Templates can be used for making solid nanorods and nanotubes of controlled sizes. Examples of templates are alumina, silicon, zeolites and lipid bilayers.

====Making modulated diameter silicon templates====
A p-doped silicon wafer is put in aqueous HF and an oxidizing potential is applied. The result from this is nanoporous silicon with a random network of pores. The diameter of the pores can be tuned by controlling the voltage or current. The higher the current is, the wider the channels get. If the current is modulated during oxidation, the resulting structure is an array of modulated diameter nanochannels. If perfectly ordered pores are desired, the wafer can be lithographically patterned with regular array of nanowells in advance. The electric field will then be focused at the tip of these wells.

====Making porous alumina membranes====
Porous alumina membranes can be made by anodic oxidation of lithograpically embossed aluminum sheet in phosphoric or oxalic acid electrolyte (the almunium sheet functions as the anode).

<math> 2Al + 3PO_4^{3-} \rightarrow Al_2O_3 + 3PO_3^{3-}</math>

The residual Al and <math>Al_2O_3</math> is removed by mercuric chloride and phosphoric acid. The diameter is controlled and can be 20-500nm. Mechanisms that give ordered channels are the fact that electric fields created by applied voltage repell each other, and that we have volume expansion when aluminum becomes alumina. Temperature is also a factor that affects the reaction.
In this process oxygen diffuses through the alumina layer from the electrolyte and alumina grows at the alumina/aluminum interface, while alumina is slowly dissolved at the alumina/electrolyte interface. This growth/dissolution comes to an equilibrium at the bottom of the pore, giving a specific thickness for a certain current/voltage. The growth of alumina is still allowed to continue upwards (along the pore walls) where the electric field is weaker, giving longer pores. Growth continues until the electric field is quenced or there is no more aluminum left.

====Modulated diameter gold nanorods====
With use of silicon template. The back surface of the silicon membrane is subjected to a local thermal oxidation which formes silica. The silica is then removed by HF. By proceeding with a KOH anisotropic etch on the same area, and a dip in HF, the pores in the template are opened. A gold sputter deposition can then be done on the backside. This gold layer acts as a catalyst for continued electroless deposition of gold. Finally, the silicon membrane is etched away, and the gold nanorod dispersion can be collected.

====Modulated composition nanorods/nanobarcodes====
Modulated composition nanorods can be made by electrochemical deposition of different metal segments within the channels of an alumina template (electrodeposition will be better explained in the following section). Any type of material that can be electrodeposited can be used in the nanobarcodes. One synthesis route is to evaporate thin metal film to one side of an alumina membrane. This metal film function as the cathode, and metal deposition begins at the bottom. Bath can be switched between different metal salts to grow several segments. The alumina membrane is dissolved using sodium hydroxide, and the metal backing is dissolved using acid.

Nanobarcodes can be used to tag molecules in analytical chemistry and biology. Characteristic of metals are optical reflectivity, which means that different segments of the barcode nanorod can be distinguished in optical microscopy. Probe molecules must be anchored to different segments, and the rods must be dispersed in analyte containing target molecules which bear a luminescent label. By molecular recognition, the target molecules bind to the probe molecules (ex: ligand-receptor binding for biological applications). By looking at the segments that light up, it can be decided which molecules excist in the solution.

====Electroplating/electrodeposition====
The part to be plated is the cathode, while the anode is made of the material to be plated. Both components are immersed in electrolyte solution. The dissolved metal ions (cations) are reduced at the interface between the solution and the cathode when current is applied.

====Electroless deposition====
This is an auto-catalytic plating method that involves several simultaneous reactions in an aqueous solution. The reaction involves plating of a metal onto a conductive surface and occurs without the use of external electrical power. This is accomplished when hydrogen is released by a reducing agent and thus producing a negative charge on the surface of the metal. There is no direct controll over length or thickness of the deposited layer. This needs to be calibrated with regards to concentration of precursor and amount of time that reaction is allowed to run.

====Nanotubes====
Nanotubes can be made by partial filling of the membranes radially. This means that a uniform coating must be deposited on the pore walls. One way to do this is by letting fluid spontaneously wet inside the template pores. Fluids that can be used are molten polymers, polymer solution or sol-gel preparation. These are coated onto template using capillary forces resulting from small diameter channels with a large available surface. Solidification of these fluids can be done by heating, cooling, waiting or using a catalyst. With this method it is difficult to control the wall thickness.
Another way to make nanotubes is by using LbL growth procedure inside the pores. This can be done by CVD of gas phase species, solution phase ALD or LbL electrostatic assembly. Wall thickness is easier to control with these methods.
Finally, the membrane is dissolved. It can also be deposited other material inside the remaining void to get coaxially coated rod or wire.

Nanotubes can also be made from LbL electrostatic coating of nanorods. The rods can be dissolved afterwards, and will leave a closed-ended tube. This method is applicable to any material that can be coated onto a nanorod and not be affected by the etching step.

====Magnetic Nanorods====
Magnetic metals such as iron, cobalt or nickel can easily be deposited into membranes. Magnetic properties are direction and size dependent. If the thickness of the magnetic segments on a nanorod is smaller than the diameter, they will self assemble into 3D bundles. If the thickness is bigger than the diameter, they will align in chains of rods. If the thickness is the same as the diameter they will be in random aggregates. Magnetic nanorods can be used for separation of molecules. A tri-segmented Au-Ni-Au nanorods can be used as affinity template for histidine- tagged proteins. Nickel selectively captures the labeled protein, and a magnetic field can be used to separate the rod with the captured protein from the rest of the solution of biomolecules. After this, the proteins can be chemically released from the magnetic nanorod. The gold segments must be in the rod to protect nickel from the etching during dissolution of alumina template after electrodeposition, and also to prevent aggregation.

====Making Single Crystal Nanowires====
Single crystal nanowires can be made by Vapor-Liquid-Solid (VLS) synthesis, Supercritical Fluid-Liquid-Solid (SFLS) synthesis or by Pulsed laser deposition.

*VLS Synthesis
A catalyst droplet first melts, then becomes saturated with precursors. Elements extrude out of the catalyst droplet as a single crystal nanowire in a furnace where the temperature is controlled to maintain liquid state of the catalyst droplet. Micrometer length with diameter less than 10 nm can be done. The diameter is controlled by the diameter of the catalyst droplet, and growth stops when the nanowire pass out of the hot zone, if the precursor is depleted or the catalyst droplet no longer is in liquid state. One example is to use laser ablation of Fe-Si target to create a Fe-Si nanocluster catalyst droplet. The Si nanowire grow with the (111) lattice planes perpendicular to the growth axis due to epitaxy at the nanocluster-nanowire interface. Doping can be done by controlling stoichometry of the target, or by introducing dopant into gas phase during growth.

*SFLS Synthesis
Similar to VLS, but used for high-eutectic temperature combinations. The solvent is pressurized above its critical point to reach higher temperatures. Can be applied to semiconductor/metal combinations (Ga/GaAs, In/InN) with eutectic temperature below 600 degrees. Au is used as catalytic seed, and diameter depends on this.

*Pulsed laser deposition
A pulsed laser is used to ablate a target (pulsed laser ablation), meaning that the pulsed laser vaporizes small parts of the target for each pulse. This creates a plume of vaporized precursor material which is allowed to deposit onto a substrate that is placed in the reaction chamber. When small catalyst particles are placed on the substrate, small single crystal nanowires can be grown. The diameter of the nanowires are determined by the size of the catalyst particles.

====Nanowires branch out====
Can create branched nanowires by VLS growth. The catalytic nanoclusters from solution placed on specific point on the body of a parent nanowire before growth. The process can be repeated for a hyper-branched construction. This could be the future development of nanowire electronics in 3D.

====Quantum Size Effects (QSE)====
QSE appear when the particle size becomes smaller than the exciton size for the material (about 5 nm for silicon). Exciton is a bound state of an electron and an electron hole in an insulator or semiconductor, which is defined by the energy gap between the valence band and the conduction band. Color of the emitted light is determined by the size of gap energy. Gap energy increases with decreasing nanowire diameter. This can be used for LEDs and lasers. Both quantum confined nanoclusters and nanowires show QSE, but anisotropy make them different. Luminescent nanocluster emits plane-polarized light, while nanorod exhibits linearly polarized light.

====Alignment methods====
Alignment methods include electric field based alignment, microfluidic alignment and Langmuir-Blodgett technique.

*Electric Field Based Alignment
Apply voltage between two micropatterned electrodes to produce electric field. Charges within a nanowire in solution become polarized, creating an attraction between the electrodes and the nanowire. The electric field is quenched when the gap between the electrodes are bridged by a nanowire. This eliminates absorption of a second nanowire at the same electrodes. Metal spots can be evaporated onto insulator surface to focus the electric field.

*Microfluidic Alignment
A PDMS stamp with a series of parallel rectangular grooves is used for this purpose. The channels are aligned under a microscope with electrodes that have been previously patterned on a substrate (these will function as metal contacts for the conducting or semiconducting lines made by this method). A drop of nanowire suspension is flowed into the microchannels by capillary forces, and solvent evaporation aligns the wires at the edges of the channels.

*Langmuir-Blodgett Technique
A Langmuir film is first created when a small amount of insoluble liquid (amphiphile) is poured onto another liquid. The balance of surface tension forces determines the profile of the meniscus formed when a substrate is pushed into this liquid. If the substrate is hydrophobic it will experience deposition of the amphiphiles during immersion. If it is hydrophilic it will experience deposition during retraction. A nanowire array can be made by firstly compressing the interface to increase the surface density of nanowires (so they align parallel to each other), and then do a double dip. The second dip must be done so that the wires align normal to the previous once.

Application areas for these methods are in LED’s, transistors and in nanowire UV photodetectors.

====LED====
A LED can be made by assembling an n-doped and a p-doped semiconductor nanowire perpendicular to each other. This is done by [TMT4320_-_Nanomaterialer#Alignment_methods|electric field based alignment] with two electrode pairs aligned perpendicular to each other where voltage is applied to one pair at a time. They can also be assembled by using the microfluidic approach. When a potential is applied across the junction, light is emitted when electrons recombine with holes at the junction between the differently doped wires. Color of the emitted light depends on composition and condition of semiconducting material used. The LED can only conduct current in one direction. With positive voltage current flows. With negative voltage current is inhibited. The key for success is to achieve abrupt and uncontaminated junction between n and p doped wire. Efficiency can be improved by using core-shell-shell nanowire axial heterostructure. The greatest challenge is to make arrays of closely spaced junctions because the nanowires are so thin. This leads to the pitch problem, how to pack light sources into smallest possible area.

====Transistors====
A transistor can switch or amplify signals, and has three terminals (n-p-n). The n-type region attached to the negative end of the battery sends electrons into p-region, and the n-type region attached to the positive end slows the electrons down. The p-type region in the middle does both. Because of this, a depletion layer develops between the base and the emitter, and the base and the collector. The thickness of the layer is varied by the potential in each region. Active bipolar n-p-n transistor can be built from heavy and lightly n-doped nanowires crossing a common p-type wire base.

====How can nanowire transistors be used as sensors?====
Si nanowires are naturally coated with silica through VLS synthesis. This makes it easy for surface silanol groups to attach to the wire. If probe molecules are anchored to the surface silanols, highly sensitive real time electrically based sensors can be made. Low levels of chemical and biological species can be detected. Boron doped silicon nanowire is used as a FET. The wire is self assembled across electrodes (source and drain), and aminoethylsilane anchored to SiOH surface groups. The conductance of the wire changes with pH linearly due to protonation or deprotonation of the amine. An increase of the surface negative charge (deprotonation) attracts additional holes into the p-channel and the conductance is enhanced. The reverse action at low pH, an increase of surface positive charge causes protonation which repell holes from the channel. The conductance is decreased. Almost any type of molecule can be anchored to silica, so sensors can be designed to detect almost anything. For example, a biotin could be strapped to the surface amine groups to detect streptavidin.

====Nanowire UV photodetector====
The conductivity of ZnO nanowires is extremely sensitive to ultraviolet light exposure, which means that UV light can switch the nanowires between ON and OFF states. ZnO nanowires are highly insulating in the dark, but UV light with wavelength less than 380 nm decreases resistivity by 4 to 6 orders of magnitude. These nanowire photoconductors exhibit excellent wavelength selectivity. Green light (532nm) gives no response, while less intense UV light increases conductivity 4 orders. The response cut-off wavelength is at about 370 nm.

====Simplifying complex nanowires====
Complex oxides with superconducting, ferroelectric and ferromagnetic properties can not easily be made as nanowires by conventional methods. MgO nanowires must be used as templates. Firstly, single crystal orthogonal MgO nanowires are grown on single crystal MgO substrate. Oxygen is flowed over <math>Mg_3N_2</math> at 900 degrees as precursor for VLS, using Au catalyst. After the MgO nanowires have been made, the complex metal oxide is deposited by pulsed laser deposition to create a shell on the surface of MgO wires. Another approach to simplify complex nanowires is to use hydrothermal synthesis. This can be used to make <math>PbTiO_3</math> nanorods which is a ferroelectric material and potentially useful as building blocks in nanoelectrochemical systems. (Amorphous <math>PbTiO_{(3-X)}OH_{2X}</math> (mulig jeg rettet feil/misforstod?) precursor is mixed with sodium dodecyl benzene sulfonate surfactant and reacted at 48 h at 180 degrees at alkaline conditions in the presence of a substrate.) The nanorods obtained have a squared cross section 35-400 nm, and up to 5 um long. The rods grow in the (001) direction by self-assembly of nanocubes to anisotropic mesocrystals, which is ripened into nanorods.

====Electrospinning====
Electrospinning is nanofiber extrusion in a capillary jet. A polymer solution or polymer sol-gel pass through a high voltage metal capillary to create a thin charged stream. The stream undergoes stretching, bending and solvent evaporation. The charged nanofibers are driven to ground electrodes. The dimensions of the fibers depend on solvent viscosity, conductivity, surface tension and precursor concentration. The collector electrodes can be patterned to make organized arrays between them by electrostatic self assembly. The electrodes can be grounded simultaneously or sequentially. This can be used to make single layer or multilayer nanowire architectures.

====Hollow nanofibers by electrospinning====
Hollow nanofibers can be made by co-axial double capillary electrospinning that creates heavy mineral oil core with inorganic polymer around (Ti and PVP). The core-shell nanofibers are collected on an aluminum or silicon substrate and hydrolyzed. The oily core can be extracted with octane, which creates nanotubes with amorphous <math>TiO_2</math> + PVP. To crystallize <math>TiO_2</math> and oxidate PVP, the tubes can be calcined in air at 500 degrees.

====Dual electrospinning====
A side by side spinneret can be used to make bicomponent fibers. Ex: two solutions containing <math>TiO_2</math>/<math>SnO_2</math> are simultaneously jetted. This is calcined. A heterojunction of <math>SnO_2</math>/<math>TiO_2</math> can create devices with extremely high quantum efficiency and photocatalytic activity for treatment of organic pollutants in water and air.

====Dette mangler:====
* Carbon nanotubes (sections 5.41, 5.42, 5.44, 5.45-5.48 and lecture notes)
** What are carbon nanotubes? Be able to describe the three different structures they can have and how their properties are different.
** Be able to describe briefly (basic principles) at least two of the three main methods used to synthesize carbon nanotubes
*** Arc discharge
*** Laser ablation
*** CVD
** How can the different structure nanotubes be separated from each other and from other carbon particles.
** Be able to say something about their properties
*** Mechanical
*** Electrical
*** Chemical
** Know some about carbon nanotube chemistry (reactivity on the surface vs the ends etc.)
** Aligning of carbon nanotubes
*** Evaporation induced self-assembly
*** Patterned hydrophilic SAM on substrate – carbon nanotubes will assemble only on the hydrophilic patches.
*** Alignment by pre-existing patterns
**** Perpendicular to substrate
**** Parallel to substrate
*** AC/DC electric fields
** Applications of carbon nanotubes
*** Sensors
*** Strengthening of materials (composites)
*** Added to materials to improve conductivity

=== Kapittel 6: Nanocluster Self-Assembly ===

====Capped nanoclusters====

A capped nanocluster is a nanometer scale particle with well-defined positions of the constituent atoms. They nucleate from atoms and enter a size range where they behave electronically as molecular nanoclusters. As the number of atoms increases further, they cross over into the nanoscale size domain where quantum size effects dominate, they become quantum dots. A capped nanocluster has a monolayer of a capping ligand on the surface, which can be a polymer or an alkane thiol (if the surface is silver or gold) or some other molecule with an end group that will bind to the surface of the nanocluster. The capping molecules will prevent further growth of the nanocluster. Capping groups serve multiple purposes:
*Change solubility properties
*Enable size-selective crystallization
*Surface functionalization
*Protect nanoclusters from luminescence or charge-carrier quenching

====General principles for synthesis of capped nanoclusters (arrested nucleation and growth)====

One general synthesis method is the arrested nucleation and growth synthesis. The basic idea is to rapidly create a large number of nucleated seeds (of desired materials) and then allow these to grow at the same rate below supersaturation conditions. This method can be described by the following steps:
* Desired precursors are added to a solution containing a proper capping agent, which is held at an intermediate temperature (200-400 °C depending on the materials. Temperature needs to be high enough to overcome the activation energy for the reaction.).
* Precursors need to be added at an amount that is over the saturation point for the materials in that specific solution.
* Materials will rapidly nucleate (precipitate) and start growing. Once the first molecules have reacted and created a small seed, the energy required for further growth is smaller than the initial activation energy. The nucleated seed can therefore continue to grow below the saturation concentration for the precursor materials.
* Once the nanoclusters reach a certain size range, which may vary from one material to the other, the capping agents will adsorb on the surface of the nanoclusters and prevent further growth. The nanoclusters that are formed will not all have the same diameter, but a range of different diameter clusters will be formed. This can be due to for example concentration gradients in the reactor or reaction medium.

====Minimize size dispersity by confining the reaction space====

The size of the capped nanoclusters can be controlled by growing them in nanowells made by the methode in figure x. The nanowells are obtained by patterning a silicon wafer with a layer of well-ordered microspheres. By pressing the microspheres against a the wafer and at the same time melt the surface of the wafer with a pulsed laser molten silicon will flow into the voids between the spheres. The size of the nanowells depend on the size of the spheres, the energy density of the laser pulse and applied mechanical pressure, while the size of the crystals depend on the well volume and concentration of the reactants. The crystals can be removed by ultrasound. The downside of the approach is that the amount of nanocrystals obtained will be quiet small.

====Tuning properties through physical dimensions rather than chemical composition (QSE)====

When electrons are confined in space the size invariant continuum of electronic states of bulk matter transformes into size dependent discrete electronic states in a quantum dot. At the 1-5 nm length scale, which is the CdSe nanocluster size range, the parent continuous electron bands of the bulk semiconductor becomes discrete. The nanoclusters then belong to the quantum size regime, and the properties begin to scale in a predictable fashion with size. By looking at the Schrödinger wave equation it can be seen that there is a blue quantum size effect shift in the energy of the first exciton band or band gap that scales with the reciprocal of the square of the radius of the nanocluster. The wavelengths absorbed change, and the colors of the nanoclusters can be alterd from yellow to red, by changing the physical size of the clusters

====How can different phases occur for smaller size particles?====

Similar to temperature and pressure, phase transformations in bulk materials are dependent on size. Phase transitions that are prohibited or slowed down by activation energies in the bulk can occur much more readily in nanocrystals of same material. Because of the small size of the crystal the influence of bulk and surface-free energies are different from in a bulk matter. Phase transformations show a distinct dependence on nanocrystal size. It can be shown that phase of nanoclusters can change just by exposing them to a different chemical environment at room temperature.

====Makeing nanoclusters water soluble====

Why? Water is cheap, widely available and use of it avoides the disposal o organic solvents, which can be quiet harmful for the environment. (Green chemistry). You can use the same principles as for the SAM surface chemistry. A hydrophilic SAM is made by choosing a hydrophilic group such as a carboxylate, ammonium or oligo ethylene glycol. In the case of a gold nanocluster, a thiol with a terminal carboxyl group gives an ionized, water loving carboxylate when in aqueous solution. Hydrophobic nanoclusters can be wrapped by amphiphilic polyers. The polymer coating is stabilized by partially cross linking the anhydride gropuos with bis(6-aminohexyl)amine. Can also coat with silica. Often, the resulting crystals bear a surface charge, which allows their use in electrostatic layer-by-layer deposition.

====Separation of nanoclusters by size using using a non-solvent and centrifugation====

Nanoclusters can be dissolved in toluene and by gradually adding a non-solvent (e.g. acetone) the nanoclusters will precipitate. The largest clusters precipitate first. Every time a bit of acetone is added the solution is centrifuged and the precipitate collected. The result is highly monodisperse nanoclusters collected in each fraction.

====Superlattice====

A superlattice is a material with periodically alternating layers of several substances. Such structures possess periodicity both on the scale of each layer's crystal lattice and on the scale of the alternating layers.

====Assembling of superlattices====

A superlattice can be assembled by means of these techniques:
*Tri-layer solvent diffusion crystallization - Three immiscible solvents are arranged to form separate layers in a test tube. Bottom layer →capped CdSe nanoclusters dissolved in toluene. Middle layer →buffer layer of 2-propanol selected for poor solvent properties wrt the nanoclusters. Top layer →non-solvent for the nanoclusters such as methanol. The process involves slow diffusion of the nanoclusters from the toluene bottom layer and the methanol from the top layer into the buffer layer. The change in solvent properties causes a slow and controlled nucleation and growth of capped CdSe nanocluster crystals.
*Sedimentation –
*Evaporation induced self-assembly – Strong capillary forces in an evaporating water meniscus drives the nanocomponents into close-packing.
*Langmuir-Blodgett – A dilute monolayer of capped silver nanoclusters is spread on an air-water interface. Using Langmuir – Blodgett “equipment”, this monolayer can gradually be compressed until a compact monolayer is formed.

====Gjenstår====

*Why do we want to make superlattices? (change of properties, properties of superlattice does not necessarily equal the sum of the properties of the individual constituents)How can capping agents (different type and length) affect the properties of a superstructure? (section 6.15)Alloying core-shell nanoclusters

* Nanocluster-polymer composites
** What is it?
** How can it be used for down-conversion of light?
* Be able to give one or two examples of how different size nanoclusters labeled with different fluorescent molecules can be used in biology.
* What is a tetrapod and what is the main priciples of the synthesis behind the tetrapod?
** Using a material that has two common crystal polymorphs where growth of one over the other can be controlled by synthesis temperature.
** Use of a long chain molecule which selectively binds to specific facets of the structure and hinders growth in those directions. This confines the growth of the material to one spatial dimension.
* Photochromic metal nanoclusters (section 6.31)
** Be able to explain what happens to silver nanoclusters embedded in a titania matrix when it is exposed to either UV-light or visible light.
* What is a buckyball and what can it be used for? What special properties does it exhibit? (Do not need to know specific details of synthesis or assembly techniques.)

=== Kapittel 7: Microspheres – Colors from the Beaker ===

Nå ferdig med så mye som forfatteren greide, men finn gjerne ut resten og del det med alle!

====What is a photonic crystal (PC)? ====
*It is a crystal consisting of a material with high dielectric contrast and periodicity at the light scale
*Wavelengths of light that are allowed to travel are known as modes, and groups of allowed modes form bands. Disallowed bands of wavelengths are called photonic band gaps (PBG).
*Vullums definition: Natural gratings that diffract light are based on dielectric lattices with periodicity at optical wavelengths. 3D optical diffraction gratings have dielectric lattices that are geometrically complimentary.
*1D PC (planes) is a crystal which only inhibit light to travel in one direction
*2D PC (rods) inhibits light to travel in two directions
*3D PC (spheres) inhibits litght to travel in any direction and has a full photonic band gap, whilst 1D and 2D only have so called stopgaps

====Photonic Crystal defects====
*Point defects: Holes, missing spheres, in a 3D PC can trap light inside the crystal
*Line defects: Many holes which make a line can guide light through a crystal
*Plane defects: A missing plane or a defect in a plane can make photons slip through to the other side. Planes consisting of another type of material can cause the perfect reflection curve of a PBG-crystal to drop at certain wavelengths depending on the size of the defect.

====Making defects====
*Writing defects: Multiphoton laser writing using a confocal optical microscope induced polymerization of an organic monomer in the colloidal crystal to create small line inside the photonic lattice. Then you treat the crystal and remove the polymer. In reversed opal structures you can use laser microwriting where you attach a laser to a scanning optical microscope which again changes the phase (which again changes the refractive index) of the inverse opal by annealing.
*Synthesizing planar defects: Introducing a dense layer or a layer with spheres of a different size than the surrounding colloidal crystal. Dense layers can be introduced by either CVD, electrolyte LbL, PDMS-stamps or maybe another deposition technique. The process consists of growing a photonic crystal, then using electrolyte LbL-deposition or PDMS-stamp make a thin film before making another photonic crystal. It's like a sandwich.

====Manipulating photonic crystals usage====
*Color of the structure is partially determined by the size of its spheres, where small spheres give blue/purple colors and larger spheres goes towards red (from yellow to green and then red).
*Non-close-packed polymerized colloidal crystalline arrays can be made to swell or shrink by external influence. As the diffraction colors of the crystal depend on the spacing between microspheres you can place a hydrogel between the spheres and this gel will swell or shrink depending on external environments. This will make the color change when the gel shrinks or swells as the pH, temperature, water concentration or ionic strength changes.
*The dielectric constant can be changed by changing the material, the structure of the crystal ''or something else that others edit in here''
*An example: Removal of cation causes a hydrogel to shrink, which can be detected at even very small concentrations. The order of cation complexation determines how sensitive the sensor is. Cation selectively binds covalently to the polymer network, sol-gel or hydrogel.

====Core-corona, core-shell-corona and multi-shell microspheres====
Core-corona and core-shell-corona can be made by both re-growth and one stage growth as multishell microspheres probably is better off being made by the re-growth process. The purpose of making these spheres is to put a lot more functionalities into just one sphere. The shells can be fluorescent, magnetic , photoactive, semiconductive, sacrificial or something else pulled out of a hat.

====Growth synthesis====
*One stage: Reagents are mixed and the microspheres are obtained in solution by a nucleation and growth
*Re-growth: First a sees is produced. The seed is then allowed to grow in several steps. Surface tension controls the shape, where low surface tension gives spherical particles.

====Self assembly of photonic crystals====
*Sedimentation (be able to explain in more detail): Use Stokes equation to make the radius as you want it by changing the viscosity very slowly.
*Electrophoresis '''– noen som veit?'''
*Hydrodynamic shear '''– noen som veit?'''
*Spin coating '''– noen som veit?'''
*Langmuir-Blodgett layer-by-layer (be able to explain in more detail) '''– noen som veit?'''
*Parallel plate confinement: Force spheres to assemble by placing them between two parallel plates and slowly moving one plate closer to the other. Important with slow movement to prevent defects. This can be done both dry and in fluid. It is necessary to increase density and viscosity of solvent so that settling occurs slowly in order to control structure and shape, and to avoid defects.
*Evaporation induced self-assembly, EISA (be able to explain in more detail) Capillary forces drive the assembly of spheres in a solution as you remove a wetting plate out of the solution. These the need to be dried and this can cause cracking. Vertical substrate is placed in a dispersion of microspheres. As solvent evaporates, the microspheres are driven by convective forces (forces from movement in solvent towards wall, surface, water meniscus) to the solvent-air meniscus. The layer thickness is determined by the diameter of the microspheres, their volume, concentration and the wetting properties of the solvent on the substrate.

====Colloidal aggregates====
*CA are made either by templated pattern in a surface or by aggregation in a homogeneous emulsion.
Emulsion-way:
*They are disperse microspheres in a solvent such as toulene.
*Add dispersion to solution of surfactant and water
*Stir or shake to get emulsion
*Toulene evapourates and as toulene droplets shrink, microspheres are pulled together in a stable cluster through capillary forces.
Photonic crystal marbles:
*Aqueous dispersion of microspheres is forced, under pressure, through a small syringe in the presence of an electric field. Surface charge on the liquid jet make it break into homogeneously sized spherical particles. Each droplet (sphere) contains a preset quantity of microspheres.
*Electrospraying - '''noen forslag?'''

====Bragg-Snell law====
*The reflected light has a wavelength depending on Bragg's and Snell's law. This then tells us that the wavelength of the first stop band is proportional to distance between the lattice plains. This gives that the longer the distance between the plains (bigger microspheres) gives longer wavelength.
<math>\lambda_{c(hkl)} = 2d_{hkl}\sqrt{\langle \epsilon \rangle - sin^2{\theta}} </math>
der <math>\langle \epsilon \rangle</math> is the effective dielectric constant of the colloidal crystal.

====Cracking====
This happens when the thin hydration layers around the crystal spheres dry out. This creates capillary stress and thermal expansion. To prevent cracking you can dry the crystal slowly, use hydrophobic spheres. Methods for preventing this is:
*<math>SiCl_4</math> reacting within the hydration layer to create a <math>SiO_2</math> layer between the spheres. Rehydrate to form multiple layers. Advantages as good control of layer thickness as it can be controlled/monitores by optical diffraction as a thicker layer res-shifts the diffraction peak.
*Necking at room temperature using vapor phase alternating chemical reactions
*Heat treatment before assembly. This may require pretreatment before assembly to give desired surface charges. Redeisperse and crystallize without volume contraction

====Liquid crystal photonic crystal====
A liquid crystal is neither a liquid nor a crystal, but an intermediate state of matter, so called mesophase. Lacks the long range order of the crystalline state and does not exhibit the randomness of the liquid state.
*Themotropics are liquid crystals which consists of melted anisotropical shapes (rods or discs) where they ar partially alligned. The order of the components in the liquid crystal is determined and changed bu the temperature.
*Two groups of thermotropics are ''nematic'', where the molecules have no positional order, but they have a long-range orientational order, and ''discotic'', which consists of disc-shaped particles that can orient in a layer-like fashion.
*By applying electric- and/or magnetic fields the small crystals in the liquid will align after the applied fields and this can control the refractive index of the film or whatever you have made out of this liquid crystal. Electric/magnetic fields or temperature changes can make it go from nearly transparent to reflective. Eksample of usage is privacy/smart windows.
*By filling the voids in an inverse opal photonic crystal with liquid crystal we make what's called a Liquid Crystal Photonic Crystal. (LCPC) Applying a field or changing the temperature makes the refractive index of the liquid crystal inside the voids change. This means that other wavelengths will satisfy Bragg's criterion, which in practice means that the color of the LCPC changes (you alter the stop band frequency) See [[TMT4320_-_Nanomaterialer#Bragg-Snell_law | Bragg-Snell law]].
*LCPC is thought to be used as tunable photonic crystal device and liquid crystal-colloidal crystal switch.

=== Reactions that you need to know: ===
* Reaction of alkane thiolate with gold. Important to know that alkane thiols have a specific affinity for gold (also keep in mind that silver and gold have very similar properties).
* Reaction that occurs when during anodic oxidation of Al to produce porous alumina membranes.
* Reaction that occurs when silica microspheres are formed from Si(OEt)4 and water (section 7.9): <math>Si(OEt)_4 + 2H_2O \rightarrow SiO_2 + 4EtOH</math>

== Eksterne linker ==
*[http://www.ntnu.no/portal/page/portal/ntnuno/AlleEmner?rootItemId=22934&selectedItemId=31007&emnekode=TMT4320 NTNUs fagbeskrivelse]
*[http://www.ntnu.no/studieinformasjon/timeplan/h08/?emnekode=TMT4320-1&valg=emnekode&bokst= Timeplan Høst08]

[[Kategori:Obligatoriske emner]]
[[Kategori:Fag 5. semester]]
[[Kategori:Fag]]

Hovedside

2008-12-15T15:06:04Z

Audunnys: typo

{| width="100%"
|-
|style="vertical-align:top" |


<div style="margin: 0 10px 0 0; border: 2px solid #dfdfdf; padding: 0 1em 1em 1em; background-color:#f8f8ff; ">
===Velkommen til Nanowiki!===
[[Nanowiki]] er en [[fagwiki]] for [[MTNANO]], sivilingeniørstudiet i [[nanoteknologi]] ved NTNU. Wikien er driftet av [[Timini]], og inneholder [[Special:Statistics|{{NUMBEROFARTICLES}}]] artikler.
</div>



<div style="font-variant: small-caps; text-align: center; margin: 10px 10px 0 0; padding: 0 1em 0 1em; ">
[[:Kategori:Fag|Fag]] | [[:Kategori:Obligatoriske emner|Obligatoriske emner]] | [[:Kategori:Utveksling|Utveksling]]</div>

<div style="text-align: center; margin: 0 10px 0 0">''[[Spesial:Kategorier|Bla gjennom kategoriene]]''</div>



<div style="margin: 10px 10px 0 0; border: 2px solid #dfdfdf; padding: 0em 1em 1em 1em; background-color: #f8f8ff; ">
<div style="width:100%;">
===Hvordan kan jeg hjelpe?===
For å komme i gang med å redigere artikler, se [[Hjelp:Hjelp|Hjelp]]. Husk også å lese [[Retningslinjer for nanowiki]] før du oppretter artikler. Deretter kan du ta en titt på [[Spesial:Ønskede_sider|listen over ønskede sider]] for inspirasjon.

For å kunne redigere artikler må du være registrert bruker og logget inn. I utgangspunktet er alle medlemmer av [[Timini]] lagt til som brukere, men dersom noen andre (forelesere, stud.asser, andre som har fag sammen med MTNANO) ønsker å bidra, ta kontakt med [[infodep]] på wiki alfakrøll timini.no for å få tildelt brukertilgang.
</div>
</div>



| width="40%" style="vertical-align:top" |

<div style="margin:0; border:2px solid #dfdfdf; padding: 0em 1em 1em 1em; background-color:#efefdf; text-align:left;">
====English info====
<div style="font-size:small; margin-left:1em;">
This wiki is run by the student association for the nano technology students at NTNU, Timini. The wiki is primarily norwegian, although some english content exists. If you want to contribute to the wiki or has any questions or feedback, please contact us at our e-mail address; wiki [at] timini.no.
</div></div>


<div style="margin: 10px 0 0 0; border:2px solid #dfdfdf; padding: 0em 1em 1em 1em; background-color:#dfefdf; ">
====Visste du at ...====
<div style="font-size:small">
{{nye}}
</div>
</div>

<div style="margin:10px 0 0 0; border:2px solid #dfdfdf; padding: 0em 1em 1em 1em; background-color:#efefdf; text-align:left;">
====Fagspørsmål====
<div style="font-size:small; margin-left:1em;">
Hvis noen har mer dyptgående spørsmål rundt fag, eller har forslag til endringer/forbedringer av fagplanen, oppfordres det til å ta kontakt med [[fagteamet]].
</div></div>

|} __NOTOC__ __NOEDITSECTION__

Mal:Nye

2008-12-15T15:05:14Z

Audunnys:

* … Det har blitt skrevet et ganske utfyllende sammendrag av [[TMT4320 - Nanomaterialer]]?
* … [[LaTeX]] automatisk oppretter innholdsfortegnelser?
* … vi har en oversikt over [[nyttige sider]]?
<noinclude>[[Kategori:Forsidemaler|{{PAGENAME}}]]</noinclude>

Hovedside

2008-12-15T14:53:25Z

Audunnys: Legger til info på engelsk og mailadresse for kontakt

{| width="100%"
|-
|style="vertical-align:top" |


<div style="margin: 0 10px 0 0; border: 2px solid #dfdfdf; padding: 0 1em 1em 1em; background-color:#f8f8ff; ">
===Velkommen til Nanowiki!===
[[Nanowiki]] er en [[fagwiki]] for [[MTNANO]], sivilingeniørstudiet i [[nanoteknologi]] ved NTNU. Wikien er driftet av [[Timini]], og inneholder [[Special:Statistics|{{NUMBEROFARTICLES}}]] artikler.
</div>



<div style="font-variant: small-caps; text-align: center; margin: 10px 10px 0 0; padding: 0 1em 0 1em; ">
[[:Kategori:Fag|Fag]] | [[:Kategori:Obligatoriske emner|Obligatoriske emner]] | [[:Kategori:Utveksling|Utveksling]]</div>

<div style="text-align: center; margin: 0 10px 0 0">''[[Spesial:Kategorier|Bla gjennom kategoriene]]''</div>



<div style="margin: 10px 10px 0 0; border: 2px solid #dfdfdf; padding: 0em 1em 1em 1em; background-color: #f8f8ff; ">
<div style="width:100%;">
===Hvordan kan jeg hjelpe?===
For å komme i gang med å redigere artikler, se [[Hjelp:Hjelp|Hjelp]]. Husk også å lese [[Retningslinjer for nanowiki]] før du oppretter artikler. Deretter kan du ta en titt på [[Spesial:Ønskede_sider|listen over ønskede sider]] for inspirasjon.

For å kunne redigere artikler må du være registrert bruker og logget inn. I utgangspunktet er alle medlemmer av [[Timini]] lagt til som brukere, men dersom noen andre (forelesere, stud.asser, andre som har fag sammen med MTNANO) ønsker å bidra, ta kontakt med [[infodep]] på wiki alfakrøll timini.no for å få tildelt brukertilgang.
</div>
</div>



| width="40%" style="vertical-align:top" |

<div style="margin:0; border:2px solid #dfdfdf; padding: 0em 1em 1em 1em; background-color:#efefdf; text-align:left;">
====English info====
<div style="font-size:small; margin-left:1em;">
This wiki is run by the student association for the nano technology students at NTNU, Timini. The wiki is primarily norwegian, although some english content exist. If you want to contribute to the wiki or has any questions or feedback, please contact us at our e-mail address; wiki [at] timini.no.
</div></div>


<div style="margin: 10px 0 0 0; border:2px solid #dfdfdf; padding: 0em 1em 1em 1em; background-color:#dfefdf; ">
====Visste du at ...====
<div style="font-size:small">
{{nye}}
</div>
</div>

<div style="margin:10px 0 0 0; border:2px solid #dfdfdf; padding: 0em 1em 1em 1em; background-color:#efefdf; text-align:left;">
====Fagspørsmål====
<div style="font-size:small; margin-left:1em;">
Hvis noen har mer dyptgående spørsmål rundt fag, eller har forslag til endringer/forbedringer av fagplanen, oppfordres det til å ta kontakt med [[fagteamet]].
</div></div>

|} __NOTOC__ __NOEDITSECTION__

TMT4320 - Nanomaterialer

2008-12-15T10:45:57Z

Audunnys: /* Making porous alumina membranes */

{{Infobox
|Fakta høst 2008
|*Foreleser: Fride Vullum
*Stud-ass: Katja Ekroll Jahren og Ørjan Fossmark Lohne
*Vurderingsform: Skriftlig eksamen
*Eksamensdato: 18. desember
}}

{{Infobox
|Øvingsopplegg høst 2008
|* Antall godkjente: 6/12
* Innleveringssted: Utenfor R7
* Frist: Tirsdager 16:00 (?)
}}

Emnet skal gi en innføring i grunnleggende kjemisk prinsipper for å lage nanomaterialer. Stikkord: "Self-assembled" monolag ([[SAM]]) og hvordan disse kan formes ved myk litografi og "dip pen" nanolitografi, syntese av tredimensjonale multilag strukturer. Tynne filmer ved kjemisk gassfase deponering. Syntese av nanopartikler, nanostaver, nanorør og nanoledninger. Våtkjemiske syntese av oksidbaserte nanomaterialer. "Self-asembly" av kolloidale mikrokuler til fotoniske krystaller, porøse nanomaterialer, blokk-kopolymere som nanomaterialer. "Self assembly" av store byggeblokker til funksjonelle anordninger.

== Oppsummering av pensum ==
Her vil det etterhvert vokse fram et lite kompendium i faget. Dette følger i utgangspunktet pensumlista som gjelder for høsten 2008.
===Chapter 1: Nanochemistry Basics ===
Not terribly important.

===Chapter 2: Soft Lithography===
====Self-assembled monolayers (SAMs)====
*The typical example of a SAM is a layer of alkanethiols on a gold substrate.
*The S-H bond is cleaved on the gold surface and an Au-S covalent bond is formed.
*The alkanethiols are tilted off-axis from the normal. The angle depends on the surface. (30 ° for a {111} gold surface, 10 ° for a silver surface).
*The end group on the alkanethiols can be tailored to achieve different monolayer properties.

====PDMS stamp====
* PDMS = PolyDiMethylSiloxane
* A master (casting) of the stamp, with the desired pattern, is made with lithography. The master is silanized and made hydrophobic so removing the stamp becomes easier.
* Liquid PDMS is then poured into the master, after which it is cured and a finished PDMS stamp is removed from the master.
* The critical dimensions of the pattern are limited by the lithography techniques used, and for [[photolithography]] the wavelengths of the light used to expose the [[photoresist]] limits the dimensions. Typical CDs given are, for lateral dimensions within the range of 500nm-200µm, and for the height of patterns 200nm-20µm.
* The PDMS stamp can be dipped in alkanethiol solutions (or solutions of other molecules, collectively known as "chemical ink") and be stamped onto surfaces
* PDMS stamps work on both planar and curved surfaces
* For the stamp to properly print a pattern onto a surface, the molecules need to adhere to the stamp from the solution, but needs to adhere more strongly to the surface to be printed on.

====Hydrophilic / Hydrophobic stamps====
* The endgroup/terminal group on the alkanethiols (or other molecules used) determine the properties of the monolayer
* By introducing a wetability gradient or abrupt changes in wetability, different effects can be obtained
** Square drops, by having checkerboard square patterns of hydrophilic monolayers with hydrophobic lines inbetween, and condensating a vapor onto the surface
** Drops "running uphill" by having wetability gradients

====Printing thin films====
* As long as the adhesion between the chemical ink and the substrate is stronger than the adhesion between the ink and the stamp, printing thin films is no problem
* Metal thin films can be evaporated onto the stamp (evaporation gives homogenous and directional coatings, not covering the side walls on the stamp) and printed onto a substrate that has been primed with a SAM with exposed thiol groups (adheres strongly to the metal layer)
* This is a very gentle technique for metal film depositing, good for making contacts on fragile layers. Also good for making 3D stuctures by printing multiple layers.
====Electrically conducting SAMS====
* Electronic devices will always need to make electrical contact with SAMs
* Other, less gentle methods of metal deposition than printing with PDMS stamps (sputtering, CVD, etc) can cause the metal layer to penetrate the SAM
* Morale: Use stamps to deposit metals on SAMs!
====Patterning by photocatalysis====
* Photocatalysis is used to remove parts of a SAM (making patterns)
* Titania can photocatalytically decompose organic molecules.
* A quartz slide patterned with titanium dioxide in the required pattern is pressed against a wafer with the SAM on it.
* The assembly is exposed to UV radiation, triggering the degradation of the (organic) SAM. When titania is exposed to UV radiation free radicals are created, which react with the organic molecues, removing the parts of the SAM that is in contact with the titania.

===Kapittel 3: Building layer-by-layer===
====Electrostatic superlattices====
* LbL multilayer films formed by alternate immersion in suspensions of opposite charges.
* A primer layer with a charge adheres to the substrate. The substrate is then dipped in a solution of polyelectrolytes of opposite charge from the primer layer. This process can be repeated numerous times in order to get the desired thickness or functionality of the film.
* As the amount and identity of constituents of each layer can be controlled, a composition gradient can easily be constructed throughout the structure.
* Any species bearing multiple ionic charges can be layered.
* Can be applied to curved surfaces like microspheres, enables applications like hollow spheres with a semipermeable cap.

====Some applications====
* Electrochromic layers (change color when a potential is applied), used in "smart windows" for instance
* Construction of cantilevers for AFMs and similar equipment, using photolithography and LbL

====Analysis, measuring film thickness====
* Optical spectroscopy: If the substrate is transparent, and the film absorbs light at a certain wavelength, the film thickness can be found by monitoring the optical absorption as a function of number of layers. A dye can be introduced to ensure absorption. Easy to perform but hard to interpret - must know the observation area and extinction coefficient of the absorbing group.
* Ellipsometry: Film is probed by polarized light, and change in polarization in the reflected light is measured. This can be used to find the refractive index, thickness, roughness and orientation of a thin film. Ellipsometry works with films much thinner than the wavelength of light - down to atomic layers.
* Quartz crystal microbalance (QCM): Quartz (piezoelectric material) in an alternating electric field contracts/expands with a characteristic oscillation frequency. When mass is added to a QCM the frequency decreases, which correlates directly with the amount of mass added. This allows real-time thickness measurements when the density of the material is known. Works well for hard materials like metals and ceramics, but not for viscoelastic materials.
* Direct techniques: Label each layer with heavy metal atoms and image by TEM. Alternately, deposit a thin gold layer on top of the surface and image cross section by TEM.

====Non-electrostatic lbl assembly====
* LbL doesn't need electrostatic bridges - can use hydrogen bonding, ligand-receptor interactions or even covalent bonds.
* Example: DNA (adenine-thymine and guanine-cytosine bridges)
* Hydrogen bonds can be broken again by changing the pH, or can be strengthened by UV irradiation

====Low-pressure layers====
* Molecular beam epitaxy (MBE): Performed in ultrahigh vacuum, sources of constituents (elemental) are heated, and a thin film alloyed from the constituents is deposited. The result is a single crystal film with homogeneous thickness grown epitaxially on the substrate. The substrate should have a similar lattice constant to that of the layer deposited. If the lattice constant of the substrate is substantially different from that of the deposited material, there will be a dewetting effect where the material can form quantum dots.
* Chemical vapor deposition (CVD): Volatile precursors are introduced in gas phase in a low-pressure reactor chamber. Argon or nitrogen gas are usually used as carrier gas to dilute the precursor and achieve optimal pressure and concentration. The substrate is heated, and the precursor decomposes at the surface. There are several different types of CVD reactors, such as cold wall and hot wall reactors. There are also plasma enhanced reactors (PECVD) where the electric field in the plasma can force growth of nanowires in the direction of the electric field.

====Lbl self-limiting reactions====
* Atomic layer deposition: Similar to CVD, but usually carried out in solution.
* Iterative saturating reactions. ALD is a self-limiting process where only one layer at a time is deposited. When the first layer is deposited it needs to be reactivated in order to grow a second layer. It is therefore easy to kontroll thickness.

=== Kapittel 4: Nanocontact printing and writing ===

''Dag H. jobber med kap.4''
====Soft lithography and microcontact printing ====
* Sub 100 nm Soft Lithography: Previous chapters has covered printing on 10.000-100 nm scale. Need for further miniaturization because of demand for more power, efficiency, and density. This can be done by manipulating PDMS stamp, Dip Pen Nanolithography (DPN), Whittling Nanostructures or by Nanoplotters

====Manipulating PDMS stamp====
* Manipulating PDMS stamp can be done in various ways, and seven of the basic ideas will now be explained. Illustrating pictures are in the book and in foils.
# Compress the stamp, mold to get a new stamp with inverse pattern, peel off and repeat.
# Apply force perpendicular onto stamp when on substrate. The areas in contact with substrate will then increase, and spaces in between gets smaller.
# Size reduction by reactive spreading of ink when in contact with substrate. The contact time + properties of the ink decide to which degree the ink spreads. The printed area is increased and the spacing between is reduced.
# Size reduction by extraction of inert filler (just like removing water from a sponge).
# Size reduction by swelling the stamp in toluene. The areas in contact with the surface are increased in size while the spacing between is reduced.
# Size reduction by stretching stamp so that dimensions get smaller in one direction and larger in another.
# Size reduction by double-printing.
* Overpressure printing
**Defect-free contact printing is restricted to a certain range of height-to-width ratios. If ratio is outside 0,2-2, the roof of the grooves on stamp will touch the substrate. Too high perpendicular force on stamp has the same effect, but overpressure can also be used to form new patterns such as micron scale discs and rings of ferromagnetic core-shell nanoparticles. Nanoparticles are then transferred to PDMS stamp by Langmuir-Blodgett technique (chapter 6) and then into contact with Au-coated silicon substrate. Low pressure => discs, high pressure => rings.
*Limitations
** Deformation can be a shortcoming if care is not taken with the dimensions of surface relief pattern in the stamp as this can give unwanted deformations. Quality of printed pattern will not be good.

====Dip pen nanolithography====
* Alkanethiols can be written on gold substrate with AFM tip. The alkanethiols are delivered to the tip via a water meniscus, and this can be adapted to suit other surface chemistries. The result is 10 nm fine patterns of molecules (biomolecules, polymers etc.) on metals, semiconductors and dielectrics.
* Sol-gel DPN: patterning of solid-state materials. Nanoscale patterns are written using a metal oxide sol-gel precursor in a solvent carrier. The sol-gel precursors are hydrolyzed to metal oxide by use of atmospheric moisture and water meniscus at the tip-substrate interface. pH, substrate temperature and post treatment can be varied.
*Enzyme DPN: A scanning microscope tip can be used to place an enzyme on a specific site on a biomolecule with nanometer presicion. This method leads to the possibility of bionanodegradable electronic and optical devices.
*Electrostatic DPN: Like thin films can be made of charged polyelectrolytes, an AFM tip can "draw" lines or structures of charged polymers with for example specific electrical properties to build nanoscale electronic devices.
*Electrochemical DPN: The meniscus that forms between surface and tip is used as a nanochemical reactor. Electrochemical deposition can be done by applying voltage between tip and substrate. Ex: making platinum lines can be done by reducing Pt salt at -4 V, and silica lines can be made by oxidation of a silicon surface at +10 V.

====Whittling of nanostructures (section 4.19)====
* Only be able to explain basic principle
**The spatial extent of SAMs can be reduced by so-called "whittling". Whittling is an electrochemical desorption process where a voltage applied will cause ligands to desorb. It has been found that the larger the accessibility of a molecule, the lower the desorbation voltage is (fig. 4.22)

====Nanoplotters and nanoblotters====
* What are these and what can they be used for?
**Nanoplotter: Parallel cantilevers write SAM nanopatterns simultaneously.
**Nanoblotters: An PDMS inkwell has been created to deliver ink to the nanoplotter cantilever tips (fig. 4.26)

====Combinatorial libraries====
* Be able to explain the basic principle and how it is used to find new and improved materials.
**DPN can be used to put different materials together in the research of new material composition. With DPN, many different combinations can be made with small material amounts used.

=== Kapittel 5: Nano-rod, nanotube, nanowire self-assembly ===

''Emily skriver på denne. Håper folk retter opp dersom de finner feil, og legg gjerne til flere ting:)''

====Templating nanowires and nanorods====
Templates can be used for making solid nanorods and nanotubes of controlled sizes. Examples of templates are alumina, silicon, zeolites and lipid bilayers.

====Making modulated diameter silicon templates====
A p-doped silicon wafer is put in aqueous HF and an oxidizing potential is applied. The result from this is nanoporous silicon with a random network of pores. The diameter of the pores can be tuned by controlling the voltage or current. The higher the current is, the wider the channels get. If the current is modulated during oxidation, the resulting structure is an array of modulated diameter nanochannels. If perfectly ordered pores are desired, the wafer can be lithographically patterned with regular array of nanowells in advance. The electric field will then be focused at the tip of these wells.

====Making porous alumina membranes====
Porous alumina membranes can be made by anodic oxidation of lithograpically embossed aluminum sheet in phosphoric or oxalic acid electrolyte (the almunium sheet functions as the anode).

<math> 2Al + 3PO_4^{3-} \rightarrow Al_2O_3 + 3PO_3^{3-}</math>

The residual Al and <math>Al_2O_3</math> is removed by mercuric chloride and phosphoric acid. The diameter is controlled and can be 20-500nm. Mechanisms that give ordered channels are the fact that electric fields created by applied voltage repell each other, and that we have volume expansion when aluminum becomes alumina. Temperature is also a factor that affects the reaction.
In this process alumina grows at the alumina/aluminum interface, while alumina is slowly dissolved at the alumina/electrolyte interface. This growth/dissolution comes to an equilibrium at the bottom of the pore, giving a specific thickness for a certain current/voltage. The growth of alumina is still allowed to continue upwards where the ele

====Modulated diameter gold nanorods====
With use of silicon template. The back surface of the silicon membrane is subjected to a local thermal oxidation which formes silica. The silica is then removed by HF. By proceeding with a KOH anisotropic etch on the same area, and a dip in HF, the pores in the template are opened. A gold sputter deposition can then be done on the backside. This gold layer acts as a catalyst for continued electroless deposition of gold. Finally, the silicon membrane is etched away, and the gold nanorod dispersion can be collected.

====Modulated composition nanorods/nanobarcodes====
Modulated composition nanorods can be made by electrochemical deposition of different metal segments within the channels of an alumina template (electrodeposition will be better explained in the following section). Any type of material that can be electrodeposited can be used in the nanobarcodes. One synthesis route is to evaporate thin metal film to one side of an alumina membrane. This metal film function as the cathode, and metal deposition begins at the bottom. Bath can be switched between different metal salts to grow several segments. The alumina membrane is dissolved using sodium hydroxide, and the metal backing is dissolved using acid.

Nanobarcodes can be used to tag molecules in analytical chemistry and biology. Characteristic of metals are optical reflectivity, which means that different segments of the barcode nanorod can be distinguished in optical microscopy. Probe molecules must be anchored to different segments, and the rods must be dispersed in analyte containing target molecules which bear a luminescent label. By molecular recognition, the target molecules bind to the probe molecules (ex: ligand-receptor binding for biological applications). By looking at the segments that light up, it can be decided which molecules excist in the solution.

====Electroplating/electrodeposition====
The part to be plated is the cathode, while the anode is made of the material to be plated. Both components are immersed in electrolyte solution. The dissolved metal ions (cations) are reduced at the interface between the solution and the cathode when current is applied.

====Electroless deposition====
Spontaneous reduction of a metal (ex: copper or silver) from a solution of its salt. A reducing agent (which acts as the source of the electrons) is required, but no current is required. The surface acts as a catalyst to allow the deposition to proceed (ex: the gold sputtered layer in making the gold nanorods in alumina).

====Nanotubes====
Nanotubes can be made by partial filling of the membranes radially. This means that a uniform coating must be deposited on the pore walls. One way to do this is by letting fluid spontaneously wet inside the template pores. Fluids that can be used are molten polymers, polymer solution or sol-gel preparation. These are coated onto template using capillary forces resulting from small diameter channels with a large available surface. Solidification of these fluids can be done by heating, cooling, waiting or using a catalyst. With this method it is difficult to control the wall thickness.
Another way to make nanotubes is by using LbL growth procedure inside the pores. This can be done by CVD of gas phase species, solution phase ALD or LbL electrostatic assembly. Wall thickness is easier to control with these methods.
Finally, the membrane is dissolved. It can also be deposited other material inside the remaining void to get coaxially coated rod or wire.

Nanotubes can also be made from LbL electrostatic coating of nanorods. The rods can be dissolved afterwards, and will leave a closed-ended tube. This method is applicable to any material that can be coated onto a nanorod and not be affected by the etching step.

====Magnetic Nanorods====
Magnetic metals such as iron, cobalt or nickel can easily be deposited into membranes. Magnetic properties are direction and size dependent. If the thickness of the magnetic segments on a nanorod is smaller than the diameter, they will self assemble into 3D bundles. If the thickness is bigger than the diameter, they will align in chains of rods. If the thickness is the same as the diameter they will be in random aggregates. Magnetic nanorods can be used for separation of molecules. A tri-segmented Au-Ni-Au nanorods can be used as affinity template for histidine- tagged proteins. Nickel selectively captures the labeled protein, and a magnetic field can be used to separate the rod with the captured protein from the rest of the solution of biomolecules. After this, the proteins can be chemically released from the magnetic nanorod. The gold segments must be in the rod to protect nickel from the etching during dissolution of alumina template after electrodeposition, and also to prevent aggregation.

====Making Single Crystal Nanowires====
Single crystal nanowires can be made by Vapor-Liquid-Solid (VLS) synthesis, Supercritical Fluid-Liquid-Solid (SFLS) synthesis or by Pulsed laser deposition.

*VLS Synthesis
A catalyst droplet first melts, then becomes saturated with precursors. Elements extrude out of the catalyst droplet as a single crystal nanowire in a furnace where the temperature is controlled to maintain liquid state of the catalyst droplet. Micrometer length with diameter less than 10 nm can be done. The diameter is controlled by the diameter of the catalyst droplet, and growth stops when the nanowire pass out of the hot zone, if the precursor is depleted or the catalyst droplet no longer is in liquid state. One example is to use laser ablation of Fe-Si target to create a Fe-Si nanocluster catalyst droplet. The Si nanowire grow with the (111) lattice planes perpendicular to the growth axis due to epitaxy at the nanocluster-nanowire interface. Doping can be done by controlling stoichometry of the target, or by introducing dopant into gas phase during growth.

*SFLS Synthesis
Similar to VLS, but used for high-eutectic temperature combinations. The solvent is pressurized above its critical point to reach higher temperatures. Can be applied to semiconductor/metal combinations (Ga/GaAs, In/InN) with eutectic temperature below 600 degrees. Au is used as catalytic seed, and diameter depends on this.

*Pulsed laser deposition
?????? laser ablation?????

====Nanowires branch out====
Can create branched nanowires by VLS growth. The catalytic nanoclusters from solution placed on specific point on the body of a parent nanowire before growth. The process can be repeated for a hyper-branched construction. This could be the future development of nanowire electronics in 3D.

====Quantum Size Effects (QSE)====
QSE appear when the particle size becomes smaller than the exciton size for the material (about 5 nm for silicon). Exciton is a bound state of an electron and an electron hole in an insulator or semiconductor, which is defined by the energy gap between the valence band and the conduction band. Color of the emitted light is determined by the size of gap energy. Gap energy increases with decreasing nanowire diameter. This can be used for LEDs and lasers. Both quantum confined nanoclusters and nanowires show QSE, but anisotropy make them different. Luminescent nanocluster emits plane-polarized light, while nanorod exhibits linearly polarized light.

====Alignment methods====
Alignment methods include electric field based alignment, microfluidic alignment and Langmuir-Blodgett technique.

*Electric Field Based Alignment
Apply voltage between two micropatterned electrodes to produce electric field. Charges within a nanowire in solution become polarized, creating an attraction between the electrodes and the nanowire. The electric field is quenched when the gap between the electrodes are bridged by a nanowire. This eliminates absorption of a second nanowire at the same electrodes. Metal spots can be evaporated onto insulator surface to focus the electric field.

*Microfluidic Alignment
A PDMS stamp with a series of parallel rectangular grooves is used for this purpose. The channels are aligned under a microscope with electrodes that have been previously patterned on a substrate (these will function as metal contacts for the conducting or semiconducting lines made by this method). A drop of nanowire suspension is flowed into the microchannels by capillary forces, and solvent evaporation aligns the wires at the edges of the channels.

*Langmuir-Blodgett Technique
A Langmuir film is first created when a small amount of insoluble liquid (amphiphile) is poured onto another liquid. The balance of surface tension forces determines the profile of the meniscus formed when a substrate is pushed into this liquid. If the substrate is hydrophobic it will experience deposition of the amphiphiles during immersion. If it is hydrophilic it will experience deposition during retraction. A nanowire array can be made by firstly compressing the interface to increase the surface density of nanowires (so they align parallel to each other), and then do a double dip. The second dip must be done so that the wires align normal to the previous once.

Application areas for these methods are in LED’s, transistors and in nanowire UV photodetectors.

====LED====
A LED is a two terminal device consisting of an n-doped and a p-doped semiconductor (eg. nanowires). To collect the doped nanowires into LED structure, voltage is firstly applied to one pair of electrodes, and then the second pair so that they lie in a cross. They can also be assembled by using the microfluidic approach. Light is emitted when electrons recombine with holes at the junction between the differently doped wires. Color of the emitted light depends on composition and condition of semiconducting material used. The LED can only conduct current in one direction. With positive voltage current flows. With negative voltage current is inhibited. The key for success is to achieve abrupt and uncontaminated junction between n and p doped wire. Efficiency can be improved by using core-shell-shell nanowire axial heterostructure. The greatest challenge is to make arrays of closely spaced junctions because the nanowires are so thin. This leads to the pitch problem, how to pack light sources into smallest possible area.

====Transistors====
A transistor can switch or amplify signals, and has three terminals (n-p-n). The n-type region attached to the negative end of the battery sends electrons into p-region, and the n-type region attached to the positive end slows the electrons down. The p-type region in the middle does both. Because of this, a depletion layer develops between the base and the emitter, and the base and the collector. The thickness of the layer is varied by the potential in each region. Active bipolar n-p-n transistor can be built from heavy and lightly n-doped nanowires crossing a common p-type wire base.

====How can nanowire transistors be used as sensors?====
Si nanowires are naturally coated with silica through VLS synthesis. This makes it easy for surface silanol groups to attach to the wire. If probe molecules are anchored to the surface silanols, highly sensitive real time electrically based sensors can be made. Low levels of chemical and biological species can be detected. Boron doped silicon nanowire is used as a FET. The wire is self assembled across electrodes (source and drain), and aminoethylsilane anchored to SiOH surface groups. The conductance of the wire changes with pH linearly due to protonation or deprotonation of the amine. An increase of the surface negative charge (deprotonation) attracts additional holes into the p-channel and the conductance is enhanced. The reverse action at low pH, an increase of surface positive charge causes protonation which repell holes from the channel. The conductance is decreased. Almost any type of molecule can be anchored to silica, so sensors can be designed to detect almost anything. For example, a biotin could be strapped to the surface amine groups to detect streptavidin.

====Nanowire UV photodetector====
The conductivity of ZnO nanowires is extremely sensitive to ultraviolet light exposure, which means that UV light can switch the nanowires between ON and OFF states. ZnO nanowires are highly insulating in the dark, but UV light with wavelength less than 380 nm decreases resistivity by 4 to 6 orders of magnitude. These nanowire photoconductors exhibit excellent wavelength selectivity. Green light (532nm) gives no response, while less intense UV light increases conductivity 4 orders. The response cut-off wavelength is at about 370 nm.

====Simplifying complex nanowires====
Complex oxides with superconducting, ferroelectric and ferromagnetic properties can not easily be made as nanowires by conventional methods. MgO nanowires must be used as templates. Firstly, single crystal orthogonal MgO nanowires are grown on single crystal MgO substrate. Oxygen is flowed over <math>Mg_3N_2</math> at 900 degrees as precursor for VLS, using Au catalyst. After the MgO nanowires have been made, the complex metal oxide is deposited by pulsed laser deposition to create a shell on the surface of MgO wires. Another approach to simplify complex nanowires is to use hydrothermal synthesis. This can be used to make <math>PbTiO_3</math> nanorods which is a ferroelectric material and potentially useful as building blocks in nanoelectrochemical systems. (Amorphous <math>PbTiO_{(3-X)}OH_{2X}</math> (mulig jeg rettet feil/misforstod?) precursor is mixed with sodium dodecyl benzene sulfonate surfactant and reacted at 48 h at 180 degrees at alkaline conditions in the presence of a substrate.) The nanorods obtained have a squared cross section 35-400 nm, and up to 5 um long. The rods grow in the (001) direction by self-assembly of nanocubes to anisotropic mesocrystals, which is ripened into nanorods.

====Electrospinning====
Electrospinning is nanofiber extrusion in a capillary jet. A polymer solution or polymer sol-gel pass through a high voltage metal capillary to create a thin charged stream. The stream undergoes stretching, bending and solvent evaporation. The charged nanofibers are driven to ground electrodes. The dimensions of the fibers depend on solvent viscosity, conductivity, surface tension and precursor concentration. The collector electrodes can be patterned to make organized arrays between them by electrostatic self assembly. The electrodes can be grounded simultaneously or sequentially. This can be used to make single layer or multilayer nanowire architectures.

====Hollow nanofibers by electrospinning====
Hollow nanofibers can be made by co-axial double capillary electrospinning that creates heavy mineral oil core with inorganic polymer around (Ti and PVP). The core-shell nanofibers are collected on an aluminum or silicon substrate and hydrolyzed. The oily core can be extracted with octane, which creates nanotubes with amorphous TiO2 + PVP. To crystallize TiO2 and oxidate PVP, the tubes can be calcined in air at 500 degrees.

====Dual electrospinning====
A side by side spinneret can be used to make bicomponent fibers. Ex: two solutions containing <math>TiO_2</math>/<math>SnO_2</math> are simultaneously jetted. This is calcined. A heterojunction of <math>SnO_2</math>/<math>TiO_2</math> can create devices with extremely high quantum efficiency and photocatalytic activity for treatment of organic pollutants in water and air.

====Dette mangler:====
* Carbon nanotubes (sections 5.41, 5.42, 5.44, 5.45-5.48 and lecture notes)
** What are carbon nanotubes? Be able to describe the three different structures they can have and how their properties are different.
** Be able to describe briefly (basic principles) at least two of the three main methods used to synthesize carbon nanotubes
*** Arc discharge
*** Laser ablation
*** CVD
** How can the different structure nanotubes be separated from each other and from other carbon particles.
** Be able to say something about their properties
*** Mechanical
*** Electrical
*** Chemical
** Know some about carbon nanotube chemistry (reactivity on the surface vs the ends etc.)
** Aligning of carbon nanotubes
*** Evaporation induced self-assembly
*** Patterned hydrophilic SAM on substrate – carbon nanotubes will assemble only on the hydrophilic patches.
*** Alignment by pre-existing patterns
**** Perpendicular to substrate
**** Parallel to substrate
*** AC/DC electric fields
** Applications of carbon nanotubes
*** Sensors
*** Strengthening of materials (composites)
*** Added to materials to improve conductivity

=== Kapittel 6: Nanocluster Self-Assembly ===

====Capped nanoclusters====

A capped nanocluster is a nanometer scale particle with well-defined positions of the constituent atoms. They nucleate from atoms and enter a size range where they behave electronically as molecular nanoclusters. As the number of atoms increases further, they cross over into the nanoscale size domain where quantum size effects dominate, they become quantum dots. A capped nanocluster has a monolayer of a capping ligand on the surface, which can be a polymer or an alkane thiol (if the surface is silver or gold) or some other molecule with an end group that will bind to the surface of the nanocluster. The capping molecules will prevent further growth of the nanocluster. Capping groups serve multiple purposes:
*Change solubility properties
*Enable size-selective crystallization
*Surface functionalization
*Protect nanoclusters from luminescence or charge-carrier quenching

====General principles for synthesis of capped nanoclusters (arrested nucleation and growth)====

One general synthesis method is the arrested nucleation and growth synthesis. The basic idea is to rapidly create a large number of nucleated seeds (of desired materials) and then allow these to grow at the same rate below supersaturation conditions. This method can be described by the following steps:
* Desired precursors are added to a solution containing a proper capping agent, which is held at an intermediate temperature (200-400 °C depending on the materials. Temperature needs to be high enough to overcome the activation energy for the reaction.).
* Precursors need to be added at an amount that is over the saturation point for the materials in that specific solution.
* Materials will rapidly nucleate (precipitate) and start growing. Once the first molecules have reacted and created a small seed, the energy required for further growth is smaller than the initial activation energy. The nucleated seed can therefore continue to grow below the saturation concentration for the precursor materials.
* Once the nanoclusters reach a certain size range, which may vary from one material to the other, the capping agents will adsorb on the surface of the nanoclusters and prevent further growth. The nanoclusters that are formed will not all have the same diameter, but a range of different diameter clusters will be formed. This can be due to for example concentration gradients in the reactor or reaction medium.

====Minimize size dispersity by confining the reaction space====

The size of the capped nanoclusters can be controlled by growing them in nanowells made by the methode in figure x. The nanowells are obtained by patterning a silicon wafer with a layer of well-ordered microspheres. By pressing the microspheres against a the wafer and at the same time melt the surface of the wafer with a pulsed laser molten silicon will flow into the voids between the spheres. The size of the nanowells depend on the size of the spheres, the energy density of the laser pulse and applied mechanical pressure, while the size of the crystals depend on the well volume and concentration of the reactants. The crystals can be removed by ultrasound. The downside of the approach is that the amount of nanocrystals obtained will be quiet small.

====Tuning properties through physical dimensions rather than chemical composition (QSE)====

When electrons are confined in space the size invariant continuum of electronic states of bulk matter transformes into size dependent discrete electronic states in a quantum dot. At the 1-5 nm length scale, which is the CdSe nanocluster size range, the parent continuous electron bands of the bulk semiconductor becomes discrete. The nanoclusters then belong to the quantum size regime, and the properties begin to scale in a predictable fashion with size. By looking at the Schrödinger wave equation it can be seen that there is a blue quantum size effect shift in the energy of the first exciton band or band gap that scales with the reciprocal of the square of the radius of the nanocluster. The wavelengths absorbed change, and the colors of the nanoclusters can be alterd from yellow to red, by changing the physical size of the clusters

====How can different phases occur for smaller size particles?====

Similar to temperature and pressure, phase transformations in bulk materials are dependent on size. Phase transitions that are prohibited or slowed down by activation energies in the bulk can occur much more readily in nanocrystals of same material. Because of the small size of the crystal the influence of bulk and surface-free energies are different from in a bulk matter. Phase transformations show a distinct dependence on nanocrystal size. It can be shown that phase of nanoclusters can change just by exposing them to a different chemical environment at room temperature.

====Makeing nanoclusters water soluble====

Why? Water is cheap, widely available and use of it avoides the disposal o organic solvents, which can be quiet harmful for the environment. (Green chemistry). You can use the same principles as for the SAM surface chemistry. A hydrophilic SAM is made by choosing a hydrophilic group such as a carboxylate, ammonium or oligo ethylene glycol. In the case of a gold nanocluster, a thiol with a terminal carboxyl group gives an ionized, water loving carboxylate when in aqueous solution. Hydrophobic nanoclusters can be wrapped by amphiphilic polyers. The polymer coating is stabilized by partially cross linking the anhydride gropuos with bis(6-aminohexyl)amine. Can also coat with silica. Often, the resulting crystals bear a surface charge, which allows their use in electrostatic layer-by-layer deposition.

====Separation of nanoclusters by size using using a non-solvent and centrifugation====

Nanoclusters can be dissolved in toluene and by gradually adding a non-solvent (e.g. acetone) the nanoclusters will precipitate. The largest clusters precipitate first. Every time a bit of acetone is added the solution is centrifuged and the precipitate collected. The result is highly monodisperse nanoclusters collected in each fraction.

====Superlattice====

A superlattice is a material with periodically alternating layers of several substances. Such structures possess periodicity both on the scale of each layer's crystal lattice and on the scale of the alternating layers.

====Assembling of superlattices====

A superlattice can be assembled by means of these techniques:
*Tri-layer solvent diffusion crystallization - Three immiscible solvents are arranged to form separate layers in a test tube. Bottom layer →capped CdSe nanoclusters dissolved in toluene. Middle layer →buffer layer of 2-propanol selected for poor solvent properties wrt the nanoclusters. Top layer →non-solvent for the nanoclusters such as methanol. The process involves slow diffusion of the nanoclusters from the toluene bottom layer and the methanol from the top layer into the buffer layer. The change in solvent properties causes a slow and controlled nucleation and growth of capped CdSe nanocluster crystals.
*Sedimentation –
*Evaporation induced self-assembly – Strong capillary forces in an evaporating water meniscus drives the nanocomponents into close-packing.
*Langmuir-Blodgett – A dilute monolayer of capped silver nanoclusters is spread on an air-water interface. Using Langmuir – Blodgett “equipment”, this monolayer can gradually be compressed until a compact monolayer is formed.

====Gjenstår====

*Why do we want to make superlattices? (change of properties, properties of superlattice does not necessarily equal the sum of the properties of the individual constituents)How can capping agents (different type and length) affect the properties of a superstructure? (section 6.15)Alloying core-shell nanoclusters

* Nanocluster-polymer composites
** What is it?
** How can it be used for down-conversion of light?
* Be able to give one or two examples of how different size nanoclusters labeled with different fluorescent molecules can be used in biology.
* What is a tetrapod and what is the main priciples of the synthesis behind the tetrapod?
** Using a material that has two common crystal polymorphs where growth of one over the other can be controlled by synthesis temperature.
** Use of a long chain molecule which selectively binds to specific facets of the structure and hinders growth in those directions. This confines the growth of the material to one spatial dimension.
* Photochromic metal nanoclusters (section 6.31)
** Be able to explain what happens to silver nanoclusters embedded in a titania matrix when it is exposed to either UV-light or visible light.
* What is a buckyball and what can it be used for? What special properties does it exhibit? (Do not need to know specific details of synthesis or assembly techniques.)

=== Kapittel 7: Microspheres – Colors from the Beaker ===

Nå ferdig med så mye som forfatteren greide, men finn gjerne ut resten og del det med alle!

====What is a photonic crystal? ====
*It is a crystal consisting of a material with high dielectric contrast and periodicity at the light scale
*Vullums definition: Natural gratings that diffract light are based on dielectric lattices with periodicity at optical wavelengths. 3D optical diffraction gratings have dielectric lattices that are geometrically complimentary.
*1D PC (planes) is a crystal which only inhibit light to travel in one direction
*2D PC (rods) inhibits light to travel in two directions
*3D PC (spheres) inhibits litght to travel in any direction and has a full photonic band gap (PBG), whilst 1D and 2D only have so called stopgaps

====Photonic Crystal defects====
*Point defects: Holes, missing spheres, in a 3D PC can trap light inside the crystal
*Line defects: Many holes which make a line can guide light through a crystal
*Plane defects: A missing plane or a defect in a plane can make photons slip through to the other side. Planes consisting of another type of material can cause the perfect reflection curve of a PBG-crystal to drop at certain wavelengths depending on the size of the defect.

====Making defects====
*Writing defects: Multiphoton laser writing using a confocal optical microscope induced polymerization of an organic monomer in the colloidal crystal to create small line inside the photonic lattice. Then you treat the crystal and remove the polymer. In reversed opal structures you can use laser microwriting where you attach a laser to a scanning optical microscope which again changes the phase (which again changes the refractive index) of the inverse opal by annealing.
*Synthesizing planar defects: Introducing a dense layer or a layer with spheres of a different size than the surrounding colloidal crystal. Dense layers can be introduced by either CVD, electrolyte LbL, PDMS-stamps or maybe another deposition technique. The process consists of growing a photonic crystal, then using electrolyte LbL-deposition or PDMS-stamp make a thin film before making another photonic crystal. It's like a sandwich.

====Manipulating photonic crystals usage====
*Color of the structure is partially determined by the size of its spheres, where small spheres give blue/purple colors and larger spheres goes towards red (from yellow to green and then red).
*Non-close-packed polymerized colloidal crystalline arrays can be made to swell or shrink by external influence. As the diffraction colors of the crystal depend on the spacing between microspheres you can place a hydrogel between the spheres and this gel will swell or shrink depending on external environments. This will make the color change when the gel shrinks or swells as the pH, temperature, water concentration or ionic strength changes.
*The dielectric constant can be changed by changing the material, the structure of the crystal ''or something else that others edit in here''
*An example: Removal of cation causes a hydrogel to shrink, which can be detected at even very small concentrations. The order of cation complexation determines how sensitive the sensor is. Cation selectively binds covalently to the polymer network, sol-gel or hydrogel.

====Core-corona, core-shell-corona and multi-shell microspheres====
Core-corona and core-shell-corona can be made by both re-growth and one stage growth as multishell microspheres probably is better off being made by the re-growth process. The purpose of making these spheres is to put a lot more functionalities into just one sphere. The shells can be fluorescent, magnetic , photoactive, semiconductive, sacrificial or something else pulled out of a hat.

====Growth synthesis====
*One stage: Reagents are mixed and the microspheres are obtained in solution by a nucleation and growth
*Re-growth: First a sees is produced. The seed is then allowed to grow in several steps. Surface tension controls the shape, where low surface tension gives spherical particles.

====Self assembly of photonic crystals====
*Sedimentation (be able to explain in more detail): Use Stokes equation to make the radius as you want it by changing the viscosity very slowly.
*Electrophoresis '''– noen som veit?'''
*Hydrodynamic shear '''– noen som veit?'''
*Spin coating '''– noen som veit?'''
*Langmuir-Blodgett layer-by-layer (be able to explain in more detail) '''– noen som veit?'''
*Parallel plate confinement: Force spheres to assemble by placing them between two parallel plates and slowly moving one plate closer to the other. Important with slow movement to prevent defects. This can be done both dry and in fluid. It is necessary to increase density and viscosity of solvent so that settling occurs slowly in order to control structure and shape, and to avoid defects.
*Evaporation induced self-assembly, EISA (be able to explain in more detail) Capillary forces drive the assembly of spheres in a solution as you remove a wetting plate out of the solution. These the need to be dried and this can cause cracking. Vertical substrate is placed in a dispersion of microspheres. As solvent evaporates, the microspheres are driven by convective forces (forces from movement in solvent towards wall, surface, water meniscus) to the solvent-air meniscus. The layer thickness is determined by the diameter of the microspheres, their volume, concentration and the wetting properties of the solvent on the substrate.

====Colloidal aggregates====
*CA are made either by templated pattern in a surface or by aggregation in a homogeneous emulsion.
Emulsion-way:
*They are disperse microspheres in a solvent such as toulene.
*Add dispersion to solution of surfactant and water
*Stir or shake to get emulsion
*Toulene evapourates and as toulene droplets shrink, microspheres are pulled together in a stable cluster through capillary forces.
Photonic crystal marbles:
*Aqueous dispersion of microspheres is forced, under pressure, through a small syringe in the presence of an electric field. Surface charge on the liquid jet make it break into homogeneously sized spherical particles. Each droplet (sphere) contains a preset quantity of microspheres.
*Electrospraying - '''noen forslag?'''

====Bragg-Snell law====
*The reflected light has a wavelength depending on Bragg's and Snell's law. This then tells us that the wavelength of the first stop band is proportional to distance between the lattice plains. This gives that the longer the distance between the plains (bigger microspheres) gives longer wavelength.
<math>\lambda_{c(hkl)} = 2d_{hkl}\sqrt{\langle \epsilon \rangle - sin^2{\theta}} </math>
der <math>\langle \epsilon \rangle</math> is the effective dielectric constant of the colloidal crystal.

====Cracking====
This happens when the thin hydration layers around the crystal spheres dry out. This creates capillary stress and thermal expansion. To prevent cracking you can dry the crystal slowly, use hydrophobic spheres. Methods for preventing this is:
*<math>SiCl_4</math> reacting within the hydration layer to create a <math>SiO_2</math> layer between the spheres. Rehydrate to form multiple layers. Advantages as good control of layer thickness as it can be controlled/monitores by optical diffraction as a thicker layer res-shifts the diffraction peak.
*Necking at room temperature using vapor phase alternating chemical reactions
*Heat treatment before assembly. This may require pretreatment before assembly to give desired surface charges. Redeisperse and crystallize without volume contraction

====Liquid crystal photonic crystal====
A liquid crystal is neither a liquid nor a crystal, but an intermediate state of matter, so called mesophase. Lacks the long range order of the crystalline state and does not exhibit the randomness of the liquid state.
*Themotropics are liquid crystals which consists of melted anisotropical shapes (rods or discs) where they ar partially alligned. The order of the components in the liquid crystal is determined and changed bu the temperature.
*Two groups of thermotropics are ''nematic'', where the molecules have no positional order, but they have a long-range orientational order, and ''discotic'', which consists of disc-shaped particles that can orient in a layer-like fashion.
*By applying electric- and/or magnetic fields the small crystals in the liquid will align after the applied fields and this can control the refractive index of the film or whatever you have made out of this liquid crystal. Electric/magnetic fields or temperature changes can make it go from nearly transparent to reflective. Eksample of usage is privacy/smart windows.
*By filling the voids in an inverse opal photonic crystal with liquid crystal we make what's called a Liquid Crystal Photonic Crystal. (LCPC) Applying a field or changing the temperature makes the refractive index of the liquid crystal inside the voids change. This means that other wavelengths will satisfy Bragg's criterion, which in practice means that the color of the LCPC changes (you alter the stop band frequency) See formula page 343.
*LCPC is thought to be used as tunable photonic crystal device and liquid crystal-colloidal crystal switch.

=== Reactions that you need to know: ===
* Reaction of alkane thiolate with gold. Important to know that alkane thiols have a specific affinity for gold (also keep in mind that silver and gold have very similar properties).
* Reaction that occurs when during anodic oxidation of Al to produce porous alumina membranes.
* Reaction that occurs when silica microspheres are formed from Si(OEt)4 and water (section 7.9): <math>Si(OEt)_4 + 2H_2O \rightarrow SiO_2 + 4EtOH</math>

== Eksterne linker ==
*[http://www.ntnu.no/portal/page/portal/ntnuno/AlleEmner?rootItemId=22934&selectedItemId=31007&emnekode=TMT4320 NTNUs fagbeskrivelse]
*[http://www.ntnu.no/studieinformasjon/timeplan/h08/?emnekode=TMT4320-1&valg=emnekode&bokst= Timeplan Høst08]

[[Kategori:Obligatoriske emner]]
[[Kategori:Fag 5. semester]]
[[Kategori:Fag]]

TMT4320 - Nanomaterialer

2008-12-15T09:15:18Z

Audunnys: /* Making modulated diameter silicon templates */

{{Infobox
|Fakta høst 2008
|*Foreleser: Fride Vullum
*Stud-ass: Katja Ekroll Jahren og Ørjan Fossmark Lohne
*Vurderingsform: Skriftlig eksamen
*Eksamensdato: 18. desember
}}

{{Infobox
|Øvingsopplegg høst 2008
|* Antall godkjente: 6/12
* Innleveringssted: Utenfor R7
* Frist: Tirsdager 16:00 (?)
}}

Emnet skal gi en innføring i grunnleggende kjemisk prinsipper for å lage nanomaterialer. Stikkord: "Self-assembled" monolag ([[SAM]]) og hvordan disse kan formes ved myk litografi og "dip pen" nanolitografi, syntese av tredimensjonale multilag strukturer. Tynne filmer ved kjemisk gassfase deponering. Syntese av nanopartikler, nanostaver, nanorør og nanoledninger. Våtkjemiske syntese av oksidbaserte nanomaterialer. "Self-asembly" av kolloidale mikrokuler til fotoniske krystaller, porøse nanomaterialer, blokk-kopolymere som nanomaterialer. "Self assembly" av store byggeblokker til funksjonelle anordninger.

== Oppsummering av pensum ==
Her vil det etterhvert vokse fram et lite kompendium i faget. Dette følger i utgangspunktet pensumlista som gjelder for høsten 2008.
===Chapter 1: Nanochemistry Basics ===
Not terribly important.

===Chapter 2: Soft Lithography===
====Self-assembled monolayers (SAMs)====
*The typical example of a SAM is a layer of alkanethiols on a gold substrate.
*The S-H bond is cleaved on the gold surface and an Au-S covalent bond is formed.
*The alkanethiols are tilted off-axis from the normal. The angle depends on the surface. (30 ° for a {111} gold surface, 10 ° for a silver surface).
*The end group on the alkanethiols can be tailored to achieve different monolayer properties.

====PDMS stamp====
* PDMS = PolyDiMethylSiloxane
* A master (casting) of the stamp, with the desired pattern, is made with lithography. The master is silanized and made hydrophobic so removing the stamp becomes easier.
* Liquid PDMS is then poured into the master, after which it is cured and a finished PDMS stamp is removed from the master.
* The critical dimensions of the pattern are limited by the lithography techniques used, and for [[photolithography]] the wavelengths of the light used to expose the [[photoresist]] limits the dimensions. Typical CDs given are, for lateral dimensions within the range of 500nm-200µm, and for the height of patterns 200nm-20µm.
* The PDMS stamp can be dipped in alkanethiol solutions (or solutions of other molecules, collectively known as "chemical ink") and be stamped onto surfaces
* PDMS stamps work on both planar and curved surfaces
* For the stamp to properly print a pattern onto a surface, the molecules need to adhere to the stamp from the solution, but needs to adhere more strongly to the surface to be printed on.

====Hydrophilic / Hydrophobic stamps====
* The endgroup/terminal group on the alkanethiols (or other molecules used) determine the properties of the monolayer
* By introducing a wetability gradient or abrupt changes in wetability, different effects can be obtained
** Square drops, by having checkerboard square patterns of hydrophobic/hydrophilic monolayers, and condensating a vapor onto the surface
** Drops "running uphill" by having wetability gradients
====Printing thin films====
* As long as the adhesion between the chemical ink and the substrate is stronger than the adhesion between the ink and the stamp, printing thin films is no problem
* Metal thin films can be evaporated onto the stamp (evaporation gives homogenous and directional coatings, not covering the side walls on the stamp) and printed onto a substrate that has been primed with a SAM with exposed thiol groups (adheres strongly to the metal layer)
* This is a very gentle technique for metal film depositing, good for making contacts on fragile layers. Also good for making 3D stuctures by printing multiple layers.
====Electrically conducting SAMS====
* Electronic devices will always need to make electrical contact with SAMs
* Other, less gentle methods of metal deposition than printing with PDMS stamps (sputtering, CVD, etc) can cause the metal layer to penetrate the SAM
* Morale: Use stamps to deposit metals on SAMs!
====Patterning by photocatalysis====
* Photocatalysis is used to remove parts of a SAM (making patterns)
* Titania can photocatalytically decompose organic molecules.
* A quartz slide patterned with titanium dioxide in the required pattern is pressed against a wafer with the SAM on it.
* The assembly is exposed to UV irradiation, triggering the degeneration of the (organic) SAM

===Kapittel 3: Building layer-by-layer===
====Electrostatic superlattices====
* Lbl multilayer films formed by alternate immersion in suspensions of opposite charges
* A primer layer with a charge adheres to the substrate. The substrate is then dipped in a solution of polyelectrolytes of opposite charge from the primer layer. Repeated with opposite charges.
* As the amount and identity of constituents of each layer can be controlled, a composition gradient can easily be constructed throughout the structure.
* Any species bearing multiple ionic charges can be layered.
* Can be applied to curved surfaces like microspheres, enables applications like hollow spheres with a semipermeable cap.

====Some applications====
* Electrochromics layers (change color when a potential is applied), used in "smart windows" for instance
* Construction of cantilevers for AFMs and similar equipment, using photolithography and lbl

====Analysis, measuring film thickness====
* Optical spectroscopy: If the substrate is transparent, and the film absorbs light at a certain wavelength, the film thickness can be found by monitoring the optical absorption as a function of number of layers. A dye can be introduced to ensure absorption. Easy to perform but hard to interpret - must know the observation area and extinction coefficient of the absorbing group.
* Ellipsometry: Film is probed by polarized light, and change in polarization in the reflected light is measured. This can be used to find the refractive index, thickness, roughness and orientation of a thin film. Ellipsometry works with films much thinner than the wavelength of light - down to atomic layers.
* Quartz crystal microbalance (QCM): Quartz (piezoelectric) in an alternating electric field contracts/expands with a characteristic oscillation frequency. When mass is added to QCM the frequency decreases. This allows real-time thickness measurements. Works well for hard materials like metals and ceramics, but not for viscoelastic materials.
* Direct techniques: Label each layer with heavy metal atoms and image by TEM. Alternately, deposit a thin gold layer on top of the surface and image cross section by TEM.

====Non-electrostatic lbl assembly====
* Lbl doesn't need electrostatic bridges - can use hydrogen bonding, ligand-receptor interactions or even covalent bonds.
* Example: DNA (adenine-thymine and guanine-cytosine bridges)
* Hydrogen bonds can be broken again by changing the pH, or can be strengthened by UV irradiation

====Low-pressure layers====
* Molecular beam epitaxy (MBE): Performed in a vacuum, sources of constituents (elemental) are heated, and a thin film alloyed from the constituents is deposited. The result is a homogeneous crystal. The substrate should have a similar lattice constant to that of the layer deposited.
* Chemical vapor deposition (CVD): Volatile precursors are introduced in gas phase in a low-pressure reactor chamber. Argon gas is used to dilute the precursor gas to achieve optimal pressure and concentration. The substrate is heated, and the precursor decomposes at the surface.

====Lbl self-limiting reactions====
* Atomic layer deposition: Similar to CVD, but usually carried out in solution.
* Iterative saturating reactions.

=== Kapittel 4: Nanocontact printing and writing ===

''Dag H. jobber med kap.4''
====Soft lithography and microcontact printing ====
* Sub 100 nm Soft Lithography: Previous chapters has covered printing on 10.000-100 nm scale. Need for further miniaturization because of demand for more power, efficiency, and density. This can be done by manipulating PDMS stamp, Dip Pen Nanolithography (DPN), Whittling Nanostructures or by Nanoplotters

====Manipulating PDMS stamp====
* Manipulating PDMS stamp can be done in various ways, and seven of the basic ideas will now be explained. Illustrating pictures are in the book and in foils.
# Compress the stamp, mold to get a new stamp with inverse pattern, peel off and repeat.
# Apply force perpendicular onto stamp when on substrate. The areas in contact with substrate will then increase, and spaces in between gets smaller.
# Size reduction by reactive spreading some sort of ink when in contact with substrate. The contact time + properties of the ink decide to which degree the ink spreads.
# Size reduction by extraction of inert filler (just like retracting water from a sponge).
# Size reduction by swelling the stamp in toluene.
# Size reduction by stretching stamp so that dimensions get smaller in one axis and larger in another.
# Size reduction by double-printing.
* Overpressure printing
**Defect-free contact printing is restricted to a certain range of height-to-width ratios. If ratio is outside 0,2-2, the roof of the grooves on stamp will touch the substrate. Too high perpendicular force on stamp has the same effect, but overpressure can also be used to form new patterns such as micron scale discs and rings of ferromagnetic core-shell nanoparticles. Nanoparticles are then transferred to PDMS stamp by Langmuir-Blodgett technique (chapter 6) and then into contact with Au-coated silicon substrate. Low pressure => discs, high pressure => rings.
*Limitations
** Deformation can be a shortcoming if care is not taken with the dimensions of surface relief pattern in the stamp as this can give unwanted deformations. Quality of printed pattern will not be good.

====Dip pen nanolithography====
* Alkanethiols can be written on gold substrate with AFM tip. The alkanethiols are delivered to the tip via a water meniscus, and this can be adapted to suit other surface chemistries. The result is 10 nm fine patterns of molecules (biomolecules, polymers etc.) on metals, semiconductors and dielectrica.
* Sol-gel DPN:patterning of solid-state materials. Nanoscale patterns are written using a metal oxide sol-gel precursor in a solvent carrier. The sol-gel precursors are hydrolyzed to metal oxide by use of atmospheric moisture and water meniscus at the tip-substrate interface. pH, substrate temperature and post treatment can be varied.
*Enzyme DPN: A scanning microscope tip can be used to place an enzyme on a specific site on a biomolecule with nanometer presicion. This method leads to the possibility of bionanodegradable electronic and optical devices.
*Electrostatic DPN: Like thin films can be made of charged polyelectrolytes, an AFM tip can "draw" lines or structures of charged polymers with for example specific electrical properties to build nanoscale electronic devices.
*Electrochemical DPN: The meniscus that forms between surface and tip is used as a nanochemical reactor. Electrochemical deposition can be done by applying voltage between tip and substrate. Ex: making platinum lines can be made by reducing Pt salt at -4 V, and silica lines can be made by oxidation of silicon surface at +10 V.

====Whittling of nanostructures (section 4.19)====
* Only be able to explain basic principle
**The spatial extent of SAMs can be reduced by so-called "whittling". Whittling is an electrochemical desorption process where a voltage applied will cause ligands to desorbate. It has been found that the larger the accessibility of a molecule, the lower the desorbation voltage is (fig. 4.22)

====Nanoplotters and nanoblotters====
* What are these and what can they be used for?
**Nanoplotter: Parallel cantilevers write SAM nanopatterns simultaneously.
**Nanoblotters: An PDMS inkwell has been created to deliver ink to the nanoplotter cantilever tips (fig. 4.26)

====Combinatorial libraries====
* Be able to explain the basic principle and how it is used to find new and improved materials.
**DPN can be used to put different materials together in the research of new material composition. With DPN, many different combinations can be made with small material amounts used.

=== Kapittel 5: Nano-rod, nanotube, nanowire self-assembly ===

''Emily skriver på denne. Håper folk retter opp dersom de finner feil, og legg gjerne til flere ting:)''

====Templating nanowires and nanorods====
Templates can be used for making solid nanowires/nanorods/nanotubes of controlled sizes. Examples of templates are alumina, silicon, zeolites and lipid bilayers.

====Making modulated diameter silicon templates====
A p-doped silicon wafer is put in aqueous HF and an oxidizing potential is applied. The result from this is nanoporous silicon with random network pores. The diameter of the pores can be tuned by controlling the voltage or current. The higher the current is, the wider the channels get. If the current is modulated during oxidation, the resulting structure is an array of modulated diameter nanochannels. If perfectly ordered pores are desired, the wafer can be lithographically patterned with regular array of nanowells in advance. The electric field will then be focused at the tip of these wells.

====Making porous alumina membranes====
Porous alumina membranes can be made by anodic oxidation of lithograpically embossed aluminum sheet in phosphoric or oxalic acid electrolyte (the almunium sheet functions as the anode).

<math> 2Al + 3PO_4^{3-} \rightarrow Al_2O_3 + 3PO_3^{3-}</math>

The residual Al and Al2O3 is removed by mercuric chloride and phosphoric acid. The diameter is controlled and can be 20-500nm. Mechanisms that give ordered channels are the fact that electric fields created by applied voltage repell each other, and that we have volume expansion when aluminum becomes alumina. Temperature is also a factor that affects the reaction.

====Modulated diameter gold nanorods====
With use of silicon template. The back surface of the silicon membrane is subjected to a local thermal oxidation which formes silica. The silica is then removed by HF. By proceeding with a KOH anisotropic etch on the same area, and a dip in HF, the pores in the template are opened. A gold sputter deposition can then be done on the backside. This gold layer acts as a catalyst for continued electroless deposition of gold. Finally, the silicon membrane is etched away, and the gold nanorod dispersion can be collected.

====Modulated composition nanorods/nanobarcodes====
Modulated composition nanorods can be made by electrochemical deposition of different metal segments within the channels of an alumina template (electrodeposition will be better explained in the following section). Any type of material that can be electrodeposited can be used in the nanobarcodes. One synthesis route is to evaporate thin metal film to one side of an alumina membrane. This metal film function as the cathode, and metal deposition begins at the bottom. Bath can be switched between different metal salts to grow several segments. The alumina membrane is dissolved using sodium hydroxide, and the metal backing is dissolved using acid.

Nanobarcodes can be used to tag molecules in analytical chemistry and biology. Characteristic of metals are optical reflectivity, which means that different segments of the barcode nanorod can be distinguished in optical microscopy. Probe molecules must be anchored to different segments, and the rods must be dispersed in analyte containing target molecules which bear a luminescent label. By molecular recognition, the target molecules bind to the probe molecules (ex: ligand-receptor binding for biological applications). By looking at the segments that light up, it can be decided which molecules excist in the solution.

====Electroplating/electrodeposition====
The part to be plated is the cathode, while the anode is made of the material to be plated. Both components are immersed in electrolyte solution. The dissolved metal ions (cations) are reduced at the interface between the solution and the cathode when current is applied.

====Electroless deposition====
Spontaneous reduction of a metal (ex: copper or silver) from a solution of its salt. A reducing agent (which acts as the source of the electrons) is required, but no current is required. The surface acts as a catalyst to allow the deposition to proceed (ex: the gold sputtered layer in making the gold nanorods in alumina).

====Nanotubes====
Nanotubes can be made by partial filling of the membranes radially. This means that a uniform coating must be deposited on the pore walls. One way to do this is by letting fluid spontaneously wet inside the template pores. Fluids that can be used are molten polymers, polymer solution or sol-gel preparation. These are coated onto template using capillary forces resulting from small diameter channels with a large available surface. Solidification of these fluids can be done by heating, cooling, waiting or using a catalyst. With this method it is difficult to control the wall thickness.
Another way to make nanotubes is by using LbL growth procedure inside the pores. This can be done by CVD of gas phase species, solution phase ALD or LbL electrostatic assembly. Wall thickness is easier to control with these methods.
Finally, the membrane is dissolved. It can also be deposited other material inside the remaining void to get coaxially coated rod or wire.

Nanotubes can also be made from LbL electrostatic coating of nanorods. The rods can be dissolved afterwards, and will leave a closed-ended tube. This method is applicable to any material that can be coated onto a nanorod and not be affected by the etching step.

====Magnetic Nanorods====
Magnetic metals such as iron, cobalt or nickel can easily be deposited into membranes. Magnetic properties are direction and size dependent. If the thickness of the magnetic segments on a nanorod is smaller than the diameter, they will self assemble into 3D bundles. If the thickness is bigger than the diameter, they will align in chains of rods. If the thickness is the same as the diameter they will be in random aggregates. Magnetic nanorods can be used for separation of molecules. A tri-segmented Au-Ni-Au nanorods can be used as affinity template for histidine- tagged proteins. Nickel selectively captures the labeled protein, and a magnetic field can be used to separate the rod with the captured protein from the rest of the solution of biomolecules. After this, the proteins can be chemically released from the magnetic nanorod. The gold segments must be in the rod to protect nickel from the etching during dissolution of alumina template after electrodeposition, and also to prevent aggregation.

====Making Single Crystal Nanowires====
Single crystal nanowires can be made by Vapor-Liquid-Solid (VLS) synthesis, Supercritical Fluid-Liquid-Solid (SFLS) synthesis or by Pulsed laser deposition.

*VLS Synthesis
A catalyst droplet first melts, then becomes saturated with precursors. Elements extrude out of the catalyst droplet as a single crystal nanowire in a furnace where the temperature is controlled to maintain liquid state of the catalyst droplet. Micrometer length with diameter less than 10 nm can be done. The diameter is controlled by the diameter of the catalyst droplet, and growth stops when the nanowire pass out of the hot zone, if the precursor is depleted or the catalyst droplet no longer is in liquid state. One example is to use laser ablation of Fe-Si target to create a Fe-Si nanocluster catalyst droplet. The Si nanowire grow with the (111) lattice planes perpendicular to the growth axis due to epitaxy at the nanocluster-nanowire interface. Doping can be done by controlling stoichometry of the target, or by introducing dopant into gas phase during growth.

*SFLS Synthesis
Similar to VLS, but used for high-eutectic temperature combinations. The solvent is pressurized above its critical point to reach higher temperatures. Can be applied to semiconductor/metal combinations (Ga/GaAs, In/InN) with eutectic temperature below 600 degrees. Au is used as catalytic seed, and diameter depends on this.

*Pulsed laser deposition
?????? laser ablation?????

====Nanowires branch out====
Can create branched nanowires by VLS growth. The catalytic nanoclusters from solution placed on specific point on the body of a parent nanowire before growth. The process can be repeated for a hyper-branched construction. This could be the future development of nanowire electronics in 3D.

====Quantum Size Effects (QSE)====
QSE appear when the particle size becomes smaller than the exciton size for the material (about 5 nm for silicon). Exciton is a bound state of an electron and an electron hole in an insulator or semiconductor, which is defined by the energy gap between the valence band and the conduction band. Color of the emitted light is determined by the size of gap energy. Gap energy increases with decreasing nanowire diameter. This can be used for LEDs and lasers. Both quantum confined nanoclusters and nanowires show QSE, but anisotropy make them different. Luminescent nanocluster emits plane-polarized light, while nanorod exhibits linearly polarized light.

====Alignment methods====
Alignment methods include electric field based alignment, microfluidic alignment and Langmuir-Blodgett technique.

*Electric Field Based Alignment
Apply voltage between two micropatterned electrodes to produce electric field. Charges within a nanowire in solution become polarized, creating an attraction between the electrodes and the nanowire. The electric field is quenched when the gap between the electrodes are bridged by a nanowire. This eliminates absorption of a second nanowire at the same electrodes. Metal spots can be evaporated onto insulator surface to focus the electric field.

*Microfluidic Alignment
A PDMS stamp with a series of parallel rectangular grooves is used for this purpose. The channels are aligned under a microscope with electrodes that have been previously patterned on a substrate (these will function as metal contacts for the conducting or semiconducting lines made by this method). A drop of nanowire suspension is flowed into the microchannels by capillary forces, and solvent evaporation aligns the wires at the edges of the channels.

*Langmuir-Blodgett Technique
A Langmuir film is first created when a small amount of insoluble liquid (amphiphile) is poured onto another liquid. The balance of surface tension forces determines the profile of the meniscus formed when a substrate is pushed into this liquid. If the substrate is hydrophobic it will experience deposition of the amphiphiles during immersion. If it is hydrophilic it will experience deposition during retraction. A nanowire array can be made by firstly compressing the interface to increase the surface density of nanowires (so they align parallel to each other), and then do a double dip. The second dip must be done so that the wires align normal to the previous once.

Application areas for these methods are in LED’s, transistors and in nanowire UV photodetectors.

====LED====
A LED is a two terminal device consisting of an n-doped and a p-doped semiconductor (eg. nanowires). To collect the doped nanowires into LED structure, voltage is firstly applied to one pair of electrodes, and then the second pair so that they lie in a cross. They can also be assembled by using the microfluidic approach. Light is emitted when electrons recombine with holes at the junction between the differently doped wires. Color of the emitted light depends on composition and condition of semiconducting material used. The LED can only conduct current in one direction. With positive voltage current flows. With negative voltage current is inhibited. The key for success is to achieve abrupt and uncontaminated junction between n and p doped wire. Efficiency can be improved by using core-shell-shell nanowire axial heterostructure. The greatest challenge is to make arrays of closely spaced junctions because the nanowires are so thin. This leads to the pitch problem, how to pack light sources into smallest possible area.

====Transistors====
A transistor can switch or amplify signals, and has three terminals (n-p-n). The n-type region attached to the negative end of the battery sends electrons into p-region, and the n-type region attached to the positive end slows the electrons down. The p-type region in the middle does both. Because of this, a depletion layer develops between the base and the emitter, and the base and the collector. The thickness of the layer is varied by the potential in each region. Active bipolar n-p-n transistor can be built from heavy and lightly n-doped nanowires crossing a common p-type wire base.

====How can nanowire transistors be used as sensors?====
Si nanowires are naturally coated with silica through VLS synthesis. This makes it easy for surface silanol groups to attach to the wire. If probe molecules are anchored to the surface silanols, highly sensitive real time electrically based sensors can be made. Low levels of chemical and biological species can be detected. Boron doped silicon nanowire is used as a FET. The wire is self assembled across electrodes (source and drain), and aminoethylsilane anchored to SiOH surface groups. The conductance of the wire changes with pH linearly due to protonation or deprotonation of the amine. An increase of the surface negative charge (deprotonation) attracts additional holes into the p-channel and the conductance is enhanced. The reverse action at low pH, an increase of surface positive charge causes protonation which repell holes from the channel. The conductance is decreased. Almost any type of molecule can be anchored to silica, so sensors can be designed to detect almost anything. For example, a biotin could be strapped to the surface amine groups to detect streptavidin.

====Nanowire UV photodetector====
The conductivity of ZnO nanowires is extremely sensitive to ultraviolet light exposure, which means that UV light can switch the nanowires between ON and OFF states. ZnO nanowires are highly insulating in the dark, but UV light with wavelength less than 380 nm decreases resistivity by 4 to 6 orders of magnitude. These nanowire photoconductors exhibit excellent wavelength selectivity. Green light (532nm) gives no response, while less intense UV light increases conductivity 4 orders. The response cut-off wavelength is at about 370 nm.

====Simplifying complex nanowires====
Complex oxides with superconducting, ferroelectric and ferromagnetic properties can not easily be made as nanowires by conventional methods. MgO nanowires must be used as templates. Firstly, single crystal orthogonal MgO nanowires are grown on single crystal MgO substrate. Oxygen is flowed over Mg3N2 at 900 degrees as precursor for VLS, using Au catalyst. After the MgO nanowires have been made, the complex metal oxide is deposited by pulsed laser deposition to create a shell on the surface of MgO wires. Another approach to simplify complex nanowires is to use hydrothermal synthesis. This can be used to make PbTiO3 nanorods which is a ferroelectric material and potentially useful as building blocks in nanoelectrochemical systems. (Amorphous PbTiO(3-X)(OH)2X precursor is mixed with sodium dodecyl benzene sulfonate surfactant and reacted at 48 h at 180 degrees at alkaline conditions in the presence of a substrate.) The nanorods obtained have a squared cross section 35-400 nm, and up to 5 um long. The rods grow in the (001) direction by self-assembly of nanocubes to anisotropic mesocrystals, which is ripened into nanorods.

====Electrospinning====
Electrospinning is nanofiber extrusion in a capillary jet. A polymer solution or polymer sol-gel pass through a high voltage metal capillary to create a thin charged stream. The stream undergoes stretching, bending and solvent evaporation. The charged nanofibers are driven to ground electrodes. The dimensions of the fibers depend on solvent viscosity, conductivity, surface tension and precursor concentration. The collector electrodes can be patterned to make organized arrays between them by electrostatic self assembly. The electrodes can be grounded simultaneously or sequentially. This can be used to make single layer or multilayer nanowire architectures.

====Hollow nanofibers by electrospinning====
Hollow nanofibers can be made by co-axial double capillary electrospinning that creates heavy mineral oil core with inorganic polymer around (Ti and PVP). The core-shell nanofibers are collected on an aluminum or silicon substrate and hydrolyzed. The oily core can be extracted with octane, which creates nanotubes with amorphous TiO2 + PVP. To crystallize TiO2 and oxidate PVP, the tubes can be calcined in air at 500 degrees.

====Dual electrospinning====
A side by side spinneret can be used to make bicomponent fibers. Ex: two solutions containing TiO2/SnO2 are simultaneously jetted. This is calcined. A heterojunction of SnO2/TiO2 can create devices with extremely high quantum efficiency and photocatalytic activity for treatment of organic pollutants in water and air.

Dette mangler:
* Carbon nanotubes (sections 5.41, 5.42, 5.44, 5.45-5.48 and lecture notes)
** What are carbon nanotubes? Be able to describe the three different structures they can have and how their properties are different.
** Be able to describe briefly (basic principles) at least two of the three main methods used to synthesize carbon nanotubes
*** Arc discharge
*** Laser ablation
*** CVD
** How can the different structure nanotubes be separated from each other and from other carbon particles.
** Be able to say something about their properties
*** Mechanical
*** Electrical
*** Chemical
** Know some about carbon nanotube chemistry (reactivity on the surface vs the ends etc.)
** Aligning of carbon nanotubes
*** Evaporation induced self-assembly
*** Patterned hydrophilic SAM on substrate – carbon nanotubes will assemble only on the hydrophilic patches.
*** Alignment by pre-existing patterns
**** Perpendicular to substrate
**** Parallel to substrate
*** AC/DC electric fields
** Applications of carbon nanotubes
*** Sensors
*** Strengthening of materials (composites)
*** Added to materials to improve conductivity

=== Kapittel 6: Nanocluster Self-Assembly ===

====Capped nanoclusters====

A capped nanocluster is a nanometer scale particle with well-defined positions of the constituent atoms. They nucleate from atoms and enter a size range where they behave electronically as molecular nanoclusters. As the number of atoms increases further, they cross over into the nanoscale size domain where quantum size effects dominate, they become quantum dots. A capped nanocluster has a monolayer of a capping ligand on the surface, which can be a polymer or an alkane thiol (if the surface is silver or gold) or some other molecule with an end group that will bind to the surface of the nanocluster. The capping molecules will prevent further growth of the nanocluster. Capping groups serve multiple purposes:
*Change solubility properties
*Enable size-selective crystallization
*Surface functionalization
*Protect nanoclusters from luminescence or charge-carrier quenching

====General principles for synthesis of capped nanoclusters (arrested nucleation and growth)====

One general synthesis method is the arrested nucleation and growth synthesis. The basic idea is to rapidly create a large number of nucleated seeds (of desired materials) and then allow these to grow at the same rate below supersaturation conditions. This method can be described by the following steps:
* Desired precursors are added to a solution containing a proper capping agent, which is held at an intermediate temperature (200-400 °C depending on the materials. Temperature needs to be high enough to overcome the activation energy for the reaction.).
* Precursors need to be added at an amount that is over the saturation point for the materials in that specific solution.
* Materials will rapidly nucleate (precipitate) and start growing. Once the first molecules have reacted and created a small seed, the energy required for further growth is smaller than the initial activation energy. The nucleated seed can therefore continue to grow below the saturation concentration for the precursor materials.
* Once the nanoclusters reach a certain size range, which may vary from one material to the other, the capping agents will adsorb on the surface of the nanoclusters and prevent further growth. The nanoclusters that are formed will not all have the same diameter, but a range of different diameter clusters will be formed. This can be due to for example concentration gradients in the reactor or reaction medium.

====Minimize size dispersity by confining the reaction space====

The size of the capped nanoclusters can be controlled by growing them in nanowells made by the methode in figure x. The nanowells are obtained by patterning a silicon wafer with a layer of well-ordered microspheres. By pressing the microspheres against a the wafer and at the same time melt the surface of the wafer with a pulsed laser molten silicon will flow into the voids between the spheres. The size of the nanowells depend on the size of the spheres, the energy density of the laser pulse and applied mechanical pressure, while the size of the crystals depend on the well volume and concentration of the reactants. The crystals can be removed by ultrasound. The downside of the approach is that the amount of nanocrystals obtained will be quiet small.

====Tuning properties through physical dimensions rather than chemical composition (QSE)====

When electrons are confined in space the size invariant continuum of electronic states of bulk matter transformes into size dependent discrete electronic states in a quantum dot. At the 1-5 nm length scale, which is the CdSe nanocluster size range, the parent continuous electron bands of the bulk semiconductor becomes discrete. The nanoclusters then belong to the quantum size regime, and the properties begin to scale in a predictable fashion with size. By looking at the Schrödinger wave equation it can be seen that there is a blue quantum size effect shift in the energy of the first exciton band or band gap that scales with the reciprocal of the square of the radius of the nanocluster. The wavelengths absorbed change, and the colors of the nanoclusters can be alterd from yellow to red, by changing the physical size of the clusters

====How can different phases occur for smaller size particles?====

Similar to temperature and pressure, phase transformations in bulk materials are dependent on size. Phase transitions that are prohibited or slowed down by activation energies in the bulk can occur much more readily in nanocrystals of same material. Because of the small size of the crystal the influence of bulk and surface-free energies are different from in a bulk matter. Phase transformations show a distinct dependence on nanocrystal size. It can be shown that phase of nanoclusters can change just by exposing them to a different chemical environment at room temperature.

====Makeing nanoclusters water soluble====

Why? Water is cheap, widely available and use of it avoides the disposal o organic solvents, which can be quiet harmful for the environment. (Green chemistry). You can use the same principles as for the SAM surface chemistry. A hydrophilic SAM is made by choosing a hydrophilic group such as a carboxylate, ammonium or oligo ethylene glycol. In the case of a gold nanocluster, a thiol with a terminal carboxyl group gives an ionized, water loving carboxylate when in aqueous solution. Hydrophobic nanoclusters can be wrapped by amphiphilic polyers. The polymer coating is stabilized by partially cross linking the anhydride gropuos with bis(6-aminohexyl)amine. Can also coat with silica. Often, the resulting crystals bear a surface charge, which allows their use in electrostatic layer-by-layer deposition.

====Separation of nanoclusters by size using using a non-solvent and centrifugation====

Nanoclusters can be dissolved in toluene and by gradually adding a non-solvent (e.g. acetone) the nanoclusters will precipitate. The largest clusters precipitate first. Every time a bit of acetone is added the solution is centrifuged and the precipitate collected. The result is highly monodisperse nanoclusters collected in each fraction.

====Superlattice====

A superlattice is a material with periodically alternating layers of several substances. Such structures possess periodicity both on the scale of each layer's crystal lattice and on the scale of the alternating layers.

====Assembling of superlattices====

A superlattice can be assembled by means of these techniques:
*Tri-layer solvent diffusion crystallization - Three immiscible solvents are arranged to form separate layers in a test tube. Bottom layer →capped CdSe nanoclusters dissolved in toluene. Middle layer →buffer layer of 2-propanol selected for poor solvent properties wrt the nanoclusters. Top layer →non-solvent for the nanoclusters such as methanol. The process involves slow diffusion of the nanoclusters from the toluene bottom layer and the methanol from the top layer into the buffer layer. The change in solvent properties causes a slow and controlled nucleation and growth of capped CdSe nanocluster crystals.
*Sedimentation –
*Evaporation induced self-assembly – Strong capillary forces in an evaporating water meniscus drives the nanocomponents into close-packing.
*Langmuir-Blodgett – A dilute monolayer of capped silver nanoclusters is spread on an air-water interface. Using Langmuir – Blodgett “equipment”, this monolayer can gradually be compressed until a compact monolayer is formed.

====Gjenstår====

*Why do we want to make superlattices? (change of properties, properties of superlattice does not necessarily equal the sum of the properties of the individual constituents)How can capping agents (different type and length) affect the properties of a superstructure? (section 6.15)Alloying core-shell nanoclusters

* Nanocluster-polymer composites
** What is it?
** How can it be used for down-conversion of light?
* Be able to give one or two examples of how different size nanoclusters labeled with different fluorescent molecules can be used in biology.
* What is a tetrapod and what is the main priciples of the synthesis behind the tetrapod?
** Using a material that has two common crystal polymorphs where growth of one over the other can be controlled by synthesis temperature.
** Use of a long chain molecule which selectively binds to specific facets of the structure and hinders growth in those directions. This confines the growth of the material to one spatial dimension.
* Photochromic metal nanoclusters (section 6.31)
** Be able to explain what happens to silver nanoclusters embedded in a titania matrix when it is exposed to either UV-light or visible light.
* What is a buckyball and what can it be used for? What special properties does it exhibit? (Do not need to know specific details of synthesis or assembly techniques.)

=== Kapittel 7: Microspheres – Colors from the Beaker ===

Nå ferdig med så mye som forfatteren greide, men finn gjerne ut resten og del det med alle!

====What is a photonic crystal? ====
*It is a crystal consisting of a material with high dielectric contrast and periodicity at the light scale
*Vullums definition: Natural gratings that diffract light are based on dielectric lattices with periodicity at optical wavelengths. 3D optical diffraction gratings have dielectric lattices that are geometrically complimentary.
*1D PC (planes) is a crystal which only inhibit light to travel in one direction
*2D PC (rods) inhibits light to travel in two directions
*3D PC (spheres) inhibits litght to travel in any direction and has a full photonic band gap (PBG), whilst 1D and 2D only have so called stopgaps

====Photonic Crystal defects====
*Point defects: Holes, missing spheres, in a 3D PC can trap light inside the crystal
*Line defects: Many holes which make a line can guide light through a crystal
*Plane defects: A missing plane or a defect in a plane can make photons slip through to the other side. Planes consisting of another type of material can cause the perfect reflection curve of a PBG-crystal to drop at certain wavelengths depending on the size of the defect.

====Making defects====
*Writing defects: Multiphoton laser writing using a confocal optical microscope induced polymerization of an organic monomer in the colloidal crystal to create small line inside the photonic lattice. Then you treat the crystal and remove the polymer. In reversed opal structures you can use laser microwriting where you attach a laser to a scanning optical microscope which again changes the phase (which again changes the refractive index) of the inverse opal by annealing.
*Synthesizing planar defects: Introducing a dense layer or a layer with spheres of a different size than the surrounding colloidal crystal. Dense layers can be introduced by either CVD, electrolyte LbL, PDMS-stamps or maybe another deposition technique. The process consists of growing a photonic crystal, then using electrolyte LbL-deposition or PDMS-stamp make a thin film before making another photonic crystal. It's like a sandwich.

====Manipulating photonic crystals usage====
*Color of the structure is partially determined by the size of its spheres, where small spheres give blue/purple colors and larger spheres goes towards red (from yellow to green and then red).
*Non-close-packed polymerized colloidal crystalline arrays can be made to swell or shrink by external influence. As the diffraction colors of the crystal depend on the spacing between microspheres you can place a hydrogel between the spheres and this gel will swell or shrink depending on external environments. This will make the color change when the gel shrinks or swells as the pH, temperature, water concentration or ionic strength changes.
*The dielectric constant can be changed by changing the material, the structure of the crystal ''or something else that others edit in here''
*An example: Removal of cation causes a hydrogel to shrink, which can be detected at even very small concentrations. The order of cation complexation determines how sensitive the sensor is. Cation selectively binds covalently to the polymer network, sol-gel or hydrogel.

====Core-corona, core-shell-corona and multi-shell microspheres====
Core-corona and core-shell-corona can be made by both re-growth and one stage growth as multishell microspheres probably is better off being made by the re-growth process. The purpose of making these spheres is to put a lot more functionalities into just one sphere. The shells can be fluorescent, magnetic , photoactive, semiconductive, sacrificial or something else pulled out of a hat.

====Growth synthesis====
*One stage: Reagents are mixed and the microspheres are obtained in solution by a nucleation and growth
*Re-growth: First a sees is produced. The seed is then allowed to grow in several steps. Surface tension controls the shape, where low surface tension gives spherical particles.

====Self assembly of photonic crystals====
*Sedimentation (be able to explain in more detail): Use Stokes equation to make the radius as you want it by changing the viscosity very slowly.
*Electrophoresis '''– noen som veit?'''
*Hydrodynamic shear '''– noen som veit?'''
*Spin coating '''– noen som veit?'''
*Langmuir-Blodgett layer-by-layer (be able to explain in more detail) '''– noen som veit?'''
*Parallel plate confinement: Force spheres to assemble by placing them between two parallel plates and slowly moving one plate closer to the other. Important with slow movement to prevent defects. This can be done both dry and in fluid. It is necessary to increase density and viscosity of solvent so that settling occurs slowly in order to control structure and shape, and to avoid defects.
*Evaporation induced self-assembly, EISA (be able to explain in more detail) Capillary forces drive the assembly of spheres in a solution as you remove a wetting plate out of the solution. These the need to be dried and this can cause cracking. Vertical substrate is placed in a dispersion of microspheres. As solvent evaporates, the microspheres are driven by convective forces (forces from movement in solvent towards wall, surface, water meniscus) to the solvent-air meniscus. The layer thickness is determined by the diameter of the microspheres, their volume, concentration and the wetting properties of the solvent on the substrate.

====Colloidal aggregates====
*CA are made either by templated pattern in a surface or by aggregation in a homogeneous emulsion.
Emulsion-way:
*They are disperse microspheres in a solvent such as toulene.
*Add dispersion to solution of surfactant and water
*Stir or shake to get emulsion
*Toulene evapourates and as toulene droplets shrink, microspheres are pulled together in a stable cluster through capillary forces.
Photonic crystal marbles:
*Aqueous dispersion of microspheres is forced, under pressure, through a small syringe in the presence of an electric field. Surface charge on the liquid jet make it break into homogeneously sized spherical particles. Each droplet (sphere) contains a preset quantity of microspheres.
*Electrospraying - '''noen forslag?'''

====Bragg-Snell law====
*The reflected light has a wavelength depending on Bragg's and Snell's law. This then tells us that the wavelength of the first stop band is proportional to distance between the lattice plains. This gives that the longer the distance between the plains (bigger microspheres) gives longer wavelength.
<math>\lambda_{c(hkl)} = 2d_{hkl}\sqrt{\langle \epsilon \rangle - sin^2{\theta}} </math>
der <math>\langle \epsilon \rangle</math> is the effective dielectric constant of the colloidal crystal.

====Cracking====
This happens when the thin hydration layers around the crystal spheres dry out. This creates capillary stress and thermal expansion. To prevent cracking you can dry the crystal slowly, use hydrophobic spheres. Methods for preventing this is:
*<math>SiCl_4</math> reacting within the hydration layer to create a <math>SiO_2</math> layer between the spheres. Rehydrate to form multiple layers. Advantages as good control of layer thickness as it can be controlled/monitores by optical diffraction as a thicker layer res-shifts the diffraction peak.
*Necking at room temperature using vapor phase alternating chemical reactions
*Heat treatment before assembly. This may require pretreatment before assembly to give desired surface charges. Redeisperse and crystallize without volume contraction

====Liquid crystal photonic crystal====
A liquid crystal is neither a liquid nor a crystal, but an intermediate state of matter, so called mesophase. Lacks the long range order of the crystalline state and does not exhibit the randomness of the liquid state.
*Themotropics are liquid crystals which consists of melted anisotropical shapes (rods or discs) where they ar partially alligned. The order of the components in the liquid crystal is determined and changed bu the temperature.
*Two groups of thermotropics are ''nematic'', where the molecules have no positional order, but they have a long-range orientational order, and ''discotic'', which consists of disc-shaped particles that can orient in a layer-like fashion.
*By applying electric- and/or magnetic fields the small crystals in the liquid will align after the applied fields and this can control the refractive index of the film or whatever you have made out of this liquid crystal. Electric/magnetic fields or temperature changes can make it go from nearly transparent to reflective. Eksample of usage is privacy/smart windows.
*By filling the voids in an inverse opal photonic crystal with liquid crystal we make what's called a Liquid Crystal Photonic Crystal. (LCPC) Applying a field or changing the temperature makes the refractive index of the liquid crystal inside the voids change. This means that other wavelengths will satisfy Bragg's criterion, which in practice means that the color of the LCPC changes (you alter the stop band frequency) See formula page 343.
*LCPC is thought to be used as tunable photonic crystal device and liquid crystal-colloidal crystal switch.

=== Reactions that you need to know: ===
* Reaction of alkane thiolate with gold. Important to know that alkane thiols have a specific affinity for gold (also keep in mind that silver and gold have very similar properties).
* Reaction that occurs when during anodic oxidation of Al to produce porous alumina membranes.
* Reaction that occurs when silica microspheres are formed from Si(OEt)4 and water (section 7.9): <math>Si(OEt)_4 + 2H_2O \rightarrow SiO_2 + 4EtOH</math>

== Eksterne linker ==
*[http://www.ntnu.no/portal/page/portal/ntnuno/AlleEmner?rootItemId=22934&selectedItemId=31007&emnekode=TMT4320 NTNUs fagbeskrivelse]
*[http://www.ntnu.no/studieinformasjon/timeplan/h08/?emnekode=TMT4320-1&valg=emnekode&bokst= Timeplan Høst08]

[[Kategori:Obligatoriske emner]]
[[Kategori:Fag 5. semester]]
[[Kategori:Fag]]

TMT4320 - Nanomaterialer

2008-12-15T08:40:18Z

Audunnys: /* Soft lithography and microcontact printing */ Formatering/omorganisering

{{Infobox
|Fakta høst 2008
|*Foreleser: Fride Vullum
*Stud-ass: ?
*Vurderingsform: Skriftlig eksamen
*Eksamensdato: 18. desember
}}

{{Infobox
|Øvingsopplegg høst 2008
|* Antall godkjente: 6/12
* Innleveringssted: Utenfor R7
* Frist: Tirsdager 16:00 (?)
}}

Emnet skal gi en innføring i grunnleggende kjemisk prinsipper for å lage nanomaterialer. Stikkord: "Self-assembled" monolag ([[SAM]]) og hvordan disse kan formes ved myk litografi og "dip pen" nanolitografi, syntese av tredimensjonale multilag strukturer. Tynne filmer ved kjemisk gassfase deponering. Syntese av nanopartikler, nanostaver, nanorør og nanoledninger. Våtkjemiske syntese av oksidbaserte nanomaterialer. "Self-asembly" av kolloidale mikrokuler til fotoniske krystaller, porøse nanomaterialer, blokk-kopolymere som nanomaterialer. "Self assembly" av store byggeblokker til funksjonelle anordninger.

== Oppsummering av pensum ==
Her vil det etterhvert vokse fram et lite kompendium i faget. Dette følger i utgangspunktet pensumlista som gjelder for høsten 2008.
===Chapter 1: Nanochemistry Basics ===
Not terribly important.

===Chapter 2: Soft Lithography===
====Self-assembled monolayers (SAMs)====
*The typical example of a SAM is a layer of alkanethiols on a gold substrate.
*The S-H bond is cleaved on the gold surface and an Au-S covalent bond is formed.
*The alkanethiols are tilted off-axis from the normal. The angle depends on the surface. (30 ° for a {111} gold surface, 10 ° for a silver surface).
*The end group on the alkanethiols can be tailored to achieve different monolayer properties.

====PDMS stamp====
* PDMS = PolyDiMethylSiloxane
* A master (casting) of the stamp, with the desired pattern, is made with lithography. The master is silanized and made hydrophobic so removing the stamp becomes easier.
* Liquid PDMS is then poured into the master, after which it is cured and a finished PDMS stamp is removed from the master.
* The critical dimensions of the pattern are limited by the lithography techniques used, and for [[photolithography]] the wavelengths of the light used to expose the [[photoresist]] limits the dimensions. Typical CDs given are, for lateral dimensions within the range of 500nm-200µm, and for the height of patterns 200nm-20µm.
* The PDMS stamp can be dipped in alkanethiol solutions (or solutions of other molecules, collectively known as "chemical ink") and be stamped onto surfaces
* PDMS stamps work on both planar and curved surfaces
* For the stamp to properly print a pattern onto a surface, the molecules need to adhere to the stamp from the solution, but needs to adhere more strongly to the surface to be printed on.

====Hydrophilic / Hydrophobic stamps====
* The endgroup/terminal group on the alkanethiols (or other molecules used) determine the properties of the monolayer
* By introducing a wetability gradient or abrupt changes in wetability, different effects can be obtained
** Square drops, by having checkerboard square patterns of hydrophobic/hydrophilic monolayers, and condensating a vapor onto the surface
** Drops "running uphill" by having wetability gradients
====Printing thin films====
* As long as the adhesion between the chemical ink and the substrate is stronger than the adhesion between the ink and the stamp, printing thin films is no problem
* Metal thin films can be evaporated onto the stamp (evaporation gives homogenous and directional coatings, not covering the side walls on the stamp) and printed onto a substrate that has been primed with a SAM with exposed thiol groups (adheres strongly to the metal layer)
* This is a very gentle technique for metal film depositing, good for making contacts on fragile layers. Also good for making 3D stuctures by printing multiple layers.
====Electrically conducting SAMS====
* Electronic devices will always need to make electrical contact with SAMs
* Other, less gentle methods of metal deposition than printing with PDMS stamps (sputtering, CVD, etc) can cause the metal layer to penetrate the SAM
* Morale: Use stamps to deposit metals on SAMs!
====Patterning by photocatalysis====
* Photocatalysis is used to remove parts of a SAM (making patterns)
* Titania can photocatalytically decompose organic molecules.
* A quartz slide patterned with titanium dioxide in the required pattern is pressed against a wafer with the SAM on it.
* The assembly is exposed to UV irradiation, triggering the degeneration of the (organic) SAM

===Kapittel 3: Building layer-by-layer===
====Electrostatic superlattices====
* Lbl multilayer films formed by alternate immersion in suspensions of opposite charges
* A primer layer with a charge adheres to the substrate. The substrate is then dipped in a solution of polyelectrolytes of opposite charge from the primer layer. Repeated with opposite charges.
* As the amount and identity of constituents of each layer can be controlled, a composition gradient can easily be constructed throughout the structure.
* Any species bearing multiple ionic charges can be layered.
* Can be applied to curved surfaces like microspheres, enables applications like hollow spheres with a semipermeable cap.

====Some applications====
* Electrochromics layers (change color when a potential is applied), used in "smart windows" for instance
* Construction of cantilevers for AFMs and similar equipment, using photolithography and lbl

====Analysis, measuring film thickness====
* Optical spectroscopy: If the substrate is transparent, and the film absorbs light at a certain wavelength, the film thickness can be found by monitoring the optical absorption as a function of number of layers. A dye can be introduced to ensure absorption. Easy to perform but hard to interpret - must know the observation area and extinction coefficient of the absorbing group.
* Ellipsometry: Film is probed by polarized light, and change in polarization in the reflected light is measured. This can be used to find the refractive index, thickness, roughness and orientation of a thin film. Ellipsometry works with films much thinner than the wavelength of light - down to atomic layers.
* Quartz crystal microbalance (QCM): Quartz (piezoelectric) in an alternating electric field contracts/expands with a characteristic oscillation frequency. When mass is added to QCM the frequency decreases. This allows real-time thickness measurements. Works well for hard materials like metals and ceramics, but not for viscoelastic materials.
* Direct techniques: Label each layer with heavy metal atoms and image by TEM. Alternately, deposit a thin gold layer on top of the surface and image cross section by TEM.

====Non-electrostatic lbl assembly====
* Lbl doesn't need electrostatic bridges - can use hydrogen bonding, ligand-receptor interactions or even covalent bonds.
* Example: DNA (adenine-thymine and guanine-cytosine bridges)
* Hydrogen bonds can be broken again by changing the pH, or can be strengthened by UV irradiation

====Low-pressure layers====
* Molecular beam epitaxy (MBE): Performed in a vacuum, sources of constituents (elemental) are heated, and a thin film alloyed from the constituents is deposited. The result is a homogeneous crystal. The substrate should have a similar lattice constant to that of the layer deposited.
* Chemical vapor deposition (CVD): Volatile precursors are introduced in gas phase in a low-pressure reactor chamber. Argon gas is used to dilute the precursor gas to achieve optimal pressure and concentration. The substrate is heated, and the precursor decomposes at the surface.

====Lbl self-limiting reactions====
* Atomic layer deposition: Similar to CVD, but usually carried out in solution.
* Iterative saturating reactions.

=== Kapittel 4: Nanocontact printing and writing ===

''Dag H. jobber med kap.4''
====Soft lithography and microcontact printing ====
* Sub 100 nm Soft Lithography: Previous chapters has covered printing on 10.000-100 nm scale. Need for further miniaturization because of demand for more power, efficiency, and density. This can be done by manipulating PDMS stamp, Dip Pen Nanolithography (DPN), Whittling Nanostructures or by Nanoplotters

====Manipulating PDMS stamp====
* Manipulating PDMS stamp can be done in various ways, and seven of the basic ideas will now be explained. Illustrating pictures are in the book and in foils.
# Compress the stamp, mold to get a new stamp with inverse pattern, peel off and repeat.
# Apply force perpendicular onto stamp when on substrate. The areas in contact with substrate will then increase, and spaces in between gets smaller.
# Size reduction by reactive spreading some sort of ink when in contact with substrate. The contact time + properties of the ink decide to which degree the ink spreads.
# Size reduction by extraction of inert filler (just like retracting water from a sponge).
# Size reduction by swelling the stamp in toluene.
# Size reduction by stretching stamp so that dimensions get smaller in one axis and larger in another.
# Size reduction by double-printing.
* Overpressure printing
**Defect-free contact printing is restricted to a certain range of height-to-width ratios. If ratio is outside 0,2-2, the roof of the grooves on stamp will touch the substrate. Too high perpendicular force on stamp has the same effect, but overpressure can also be used to form new patterns such as micron scale discs and rings of ferromagnetic core-shell nanoparticles. Nanoparticles are then transferred to PDMS stamp by Langmuir-Blodgett technique (chapter 6) and then into contact with Au-coated silicon substrate. Low pressure => discs, high pressure => rings.
*Limitations
** Deformation can be a shortcoming if care is not taken with the dimensions of surface relief pattern in the stamp as this can give unwanted deformations. Quality of printed pattern will not be good.

====Dip pen nanolithography====
* Alkanethiols can be written on gold substrate with AFM tip. The alkanethiols are delivered to the tip via a water meniscus, and this can be adapted to suit other surface chemistries. The result is 10 nm fine patterns of molecules (biomolecules, polymers etc.) on metals, semiconductors and dielectrica.
* Sol-gel DPN:patterning of solid-state materials. Nanoscale patterns are written using a metal oxide sol-gel precursor in a solvent carrier. The sol-gel precursors are hydrolyzed to metal oxide by use of atmospheric moisture and water meniscus at the tip-substrate interface. pH, substrate temperature and post treatment can be varied.
*Enzyme DPN: A scanning microscope tip can be used to place an enzyme on a specific site on a biomolecule with nanometer presicion. This method leads to the possibility of bionanodegradable electronic and optical devices.
*Electrostatic DPN: Like thin films can be made of charged polyelectrolytes, an AFM tip can "draw" lines or structures of charged polymers with for example specific electrical properties to build nanoscale electronic devices.
*Electrochemical DPN: The meniscus that forms between surface and tip is used as a nanochemical reactor. Electrochemical deposition can be done by applying voltage between tip and substrate. Ex: making platinum lines can be made by reducing Pt salt at -4 V, and silica lines can be made by oxidation of silicon surface at +10 V.

====Whittling of nanostructures (section 4.19)====
* Only be able to explain basic principle
**The spatial extent of SAMs can be reduced by so-called "whittling". Whittling is an electrochemical desorption process where a voltage applied will cause ligands to desorbate. It has been found that the larger the accessibility of a molecule, the lower the desorbation voltage is (fig. 4.22)

====Nanoplotters and nanoblotters====
* What are these and what can they be used for?
**Nanoplotter: Parallel cantilevers write SAM nanopatterns simultaneously.
**Nanoblotters: An PDMS inkwell has been created to deliver ink to the nanoplotter cantilever tips (fig. 4.26)

====Combinatorial libraries====
* Be able to explain the basic principle and how it is used to find new and improved materials.
**DPN can be used to put different materials together in the research of new material composition. With DPN, many different combinations can be made with small material amounts used.

=== Kapittel 5: Nano-rod, nanotube, nanowire self-assembly ===

''Emily skriver på denne. Håper folk retter opp dersom de finner feil, og legg gjerne til flere ting:)''

====Templating nanowires and nanorods====
Templates can be used for making solid nanowires/nanorods/nanotubes of controlled sizes. Examples of templates are alumina, silicon, zeolites and lipid bilayers.

====Making modulated diameter silicon templates====
A p+ doped silicon wafer is put in aqueous HF and an oxidizing potential is applied. The result from this is nanoporous silicon with random network pores. The diameter of the pores can be tuned by controlling the voltage or current. The higher the current is, the wider the channels get. If perfectly ordered pores are desired, the wafer can be lithographically patterned with regular array of nanowells in advance. The electric field will then be focused at the tip of these wells.

====Making porous alumina membranes====
Porous alumina membranes can be made by anodic oxidation of lithograpically embossed aluminum sheet in phosphoric or oxalic acid electrolyte (the almunium sheet functions as the anode).

<math> 2Al + 3PO_4^{3-} \rightarrow Al_2O_3 + 3PO_3^{3-}</math>

The residual Al and Al2O3 is removed by mercuric chloride and phosphoric acid. The diameter is controlled and can be 20-500nm. Mechanisms that give ordered channels are the fact that electric fields created by applied voltage repell each other, and that we have volume expansion when aluminum becomes alumina. Temperature is also a factor that affects the reaction.

====Modulated diameter gold nanorods====
With use of silicon template. The back surface of the silicon membrane is subjected to a local thermal oxidation which formes silica. The silica is then removed by HF. By proceeding with a KOH anisotropic etch on the same area, and a dip in HF, the pores in the template are opened. A gold sputter deposition can then be done on the backside. This gold layer acts as a catalyst for continued electroless deposition of gold. Finally, the silicon membrane is etched away, and the gold nanorod dispersion can be collected.

====Modulated composition nanorods/nanobarcodes====
Modulated composition nanorods can be made by electrochemical deposition of different metal segments within the channels of an alumina template (electrodeposition will be better explained in the following section). Any type of material that can be electrodeposited can be used in the nanobarcodes. One synthesis route is to evaporate thin metal film to one side of an alumina membrane. This metal film function as the cathode, and metal deposition begins at the bottom. Bath can be switched between different metal salts to grow several segments. The alumina membrane is dissolved using sodium hydroxide, and the metal backing is dissolved using acid.

Nanobarcodes can be used to tag molecules in analytical chemistry and biology. Characteristic of metals are optical reflectivity, which means that different segments of the barcode nanorod can be distinguished in optical microscopy. Probe molecules must be anchored to different segments, and the rods must be dispersed in analyte containing target molecules which bear a luminescent label. By molecular recognition, the target molecules bind to the probe molecules (ex: ligand-receptor binding for biological applications). By looking at the segments that light up, it can be decided which molecules excist in the solution.

====Electroplating/electrodeposition====
The part to be plated is the cathode, while the anode is made of the material to be plated. Both components are immersed in electrolyte solution. The dissolved metal ions (cations) are reduced at the interface between the solution and the cathode when current is applied.

====Electroless deposition====
Spontaneous reduction of a metal (ex: copper or silver) from a solution of its salt. A reducing agent (which acts as the source of the electrons) is required, but no current is required. The surface acts as a catalyst to allow the deposition to proceed (ex: the gold sputtered layer in making the gold nanorods in alumina).

====Nanotubes====
Nanotubes can be made by partial filling of the membranes radially. This means that a uniform coating must be deposited on the pore walls. One way to do this is by letting fluid spontaneously wet inside the template pores. Fluids that can be used are molten polymers, polymer solution or sol-gel preparation. These are coated onto template using capillary forces resulting from small diameter channels with a large available surface. Solidification of these fluids can be done by heating, cooling, waiting or using a catalyst. With this method it is difficult to control the wall thickness.
Another way to make nanotubes is by using LbL growth procedure inside the pores. This can be done by CVD of gas phase species, solution phase ALD or LbL electrostatic assembly. Wall thickness is easier to control with these methods.
Finally, the membrane is dissolved. It can also be deposited other material inside the remaining void to get coaxially coated rod or wire.

Nanotubes can also be made from LbL electrostatic coating of nanorods. The rods can be dissolved afterwards, and will leave a closed-ended tube. This method is applicable to any material that can be coated onto a nanorod and not be affected by the etching step.

====Magnetic Nanorods====
Magnetic metals such as iron, cobalt or nickel can easily be deposited into membranes. Magnetic properties are direction and size dependent. If the thickness of the magnetic segments on a nanorod is smaller than the diameter, they will self assemble into 3D bundles. If the thickness is bigger than the diameter, they will align in chains of rods. If the thickness is the same as the diameter they will be in random aggregates. Magnetic nanorods can be used for separation of molecules. A tri-segmented Au-Ni-Au nanorods can be used as affinity template for histidine- tagged proteins. Nickel selectively captures the labeled protein, and a magnetic field can be used to separate the rod with the captured protein from the rest of the solution of biomolecules. After this, the proteins can be chemically released from the magnetic nanorod. The gold segments must be in the rod to protect nickel from the etching during dissolution of alumina template after electrodeposition, and also to prevent aggregation.

====Making Single Crystal Nanowires====
Single crystal nanowires can be made by Vapor-Liquid-Solid (VLS) synthesis, Supercritical Fluid-Liquid-Solid (SFLS) synthesis or by Pulsed laser deposition.

*VLS Synthesis
A catalyst droplet first melts, then becomes saturated with precursors. Elements extrude out of the catalyst droplet as a single crystal nanowire in a furnace where the temperature is controlled to maintain liquid state of the catalyst droplet. Micrometer length with diameter less than 10 nm can be done. The diameter is controlled by the diameter of the catalyst droplet, and growth stops when the nanowire pass out of the hot zone, if the precursor is depleted or the catalyst droplet no longer is in liquid state. One example is to use laser ablation of Fe-Si target to create a Fe-Si nanocluster catalyst droplet. The Si nanowire grow with the (111) lattice planes perpendicular to the growth axis due to epitaxy at the nanocluster-nanowire interface. Doping can be done by controlling stoichometry of the target, or by introducing dopant into gas phase during growth.

*SFLS Synthesis
Similar to VLS, but used for high-eutectic temperature combinations. The solvent is pressurized above its critical point to reach higher temperatures. Can be applied to semiconductor/metal combinations (Ga/GaAs, In/InN) with eutectic temperature below 600 degrees. Au is used as catalytic seed, and diameter depends on this.

*Pulsed laser deposition
?????? laser ablation?????

====Nanowires branch out====
Can create branched nanowires by VLS growth. The catalytic nanoclusters from solution placed on specific point on the body of a parent nanowire before growth. The process can be repeated for a hyper-branched construction. This could be the future development of nanowire electronics in 3D.

====Quantum Size Effects (QSE)====
QSE appear when the particle size becomes smaller than the exciton size for the material (about 5 nm for silicon). Exciton is a bound state of an electron and an electron hole in an insulator or semiconductor, which is defined by the energy gap between the valence band and the conduction band. Color of the emitted light is determined by the size of gap energy. Gap energy increases with decreasing nanowire diameter. This can be used for LEDs and lasers. Both quantum confined nanoclusters and nanowires show QSE, but anisotropy make them different. Luminescent nanocluster emits plane-polarized light, while nanorod exhibits linearly polarized light.

====Alignment methods====
Alignment methods include electric field based alignment, microfluidic alignment and Langmuir-Blodgett technique.

*Electric Field Based Alignment
Apply voltage between two micropatterned electrodes to produce electric field. Charges within a nanowire in solution become polarized, creating an attraction between the electrodes and the nanowire. The electric field is quenched when the gap between the electrodes are bridged by a nanowire. This eliminates absorption of a second nanowire at the same electrodes. Metal spots can be evaporated onto insulator surface to focus the electric field.

*Microfluidic Alignment
A PDMS stamp with a series of parallel rectangular grooves is used for this purpose. The channels are aligned under a microscope with electrodes that have been previously patterned on a substrate (these will function as metal contacts for the conducting or semiconducting lines made by this method). A drop of nanowire suspension is flowed into the microchannels by capillary forces, and solvent evaporation aligns the wires at the edges of the channels.

*Langmuir-Blodgett Technique
A Langmuir film is first created when a small amount of insoluble liquid (amphiphile) is poured onto another liquid. The balance of surface tension forces determines the profile of the meniscus formed when a substrate is pushed into this liquid. If the substrate is hydrophobic it will experience deposition of the amphiphiles during immersion. If it is hydrophilic it will experience deposition during retraction. A nanowire array can be made by firstly compressing the interface to increase the surface density of nanowires (so they align parallel to each other), and then do a double dip. The second dip must be done so that the wires align normal to the previous once.

Application areas for these methods are in LED’s, transistors and in nanowire UV photodetectors.

====LED====
A LED is a two terminal device consisting of an n-doped and a p-doped semiconductor (eg. nanowires). To collect the doped nanowires into LED structure, voltage is firstly applied to one pair of electrodes, and then the second pair so that they lie in a cross. They can also be assembled by using the microfluidic approach. Light is emitted when electrons recombine with holes at the junction between the differently doped wires. Color of the emitted light depends on composition and condition of semiconducting material used. The LED can only conduct current in one direction. With positive voltage current flows. With negative voltage current is inhibited. The key for success is to achieve abrupt and uncontaminated junction between n and p doped wire. Efficiency can be improved by using core-shell-shell nanowire axial heterostructure. The greatest challenge is to make arrays of closely spaced junctions because the nanowires are so thin. This leads to the pitch problem, how to pack light sources into smallest possible area.

====Transistors====
A transistor can switch or amplify signals, and has three terminals (n-p-n). The n-type region attached to the negative end of the battery sends electrons into p-region, and the n-type region attached to the positive end slows the electrons down. The p-type region in the middle does both. Because of this, a depletion layer develops between the base and the emitter, and the base and the collector. The thickness of the layer is varied by the potential in each region. Active bipolar n-p-n transistor can be built from heavy and lightly n-doped nanowires crossing a common p-type wire base.

====How can nanowire transistors be used as sensors?====
Si nanowires are naturally coated with silica through VLS synthesis. This makes it easy for surface silanol groups to attach to the wire. If probe molecules are anchored to the surface silanols, highly sensitive real time electrically based sensors can be made. Low levels of chemical and biological species can be detected. Boron doped silicon nanowire is used as a FET. The wire is self assembled across electrodes (source and drain), and aminoethylsilane anchored to SiOH surface groups. The conductance of the wire changes with pH linearly due to protonation or deprotonation of the amine. An increase of the surface negative charge (deprotonation) attracts additional holes into the p-channel and the conductance is enhanced. The reverse action at low pH, an increase of surface positive charge causes protonation which repell holes from the channel. The conductance is decreased. Almost any type of molecule can be anchored to silica, so sensors can be designed to detect almost anything. For example, a biotin could be strapped to the surface amine groups to detect streptavidin.

====Nanowire UV photodetector====
The conductivity of ZnO nanowires is extremely sensitive to ultraviolet light exposure, which means that UV light can switch the nanowires between ON and OFF states. ZnO nanowires are highly insulating in the dark, but UV light with wavelength less than 380 nm decreases resistivity by 4 to 6 orders of magnitude. These nanowire photoconductors exhibit excellent wavelength selectivity. Green light (532nm) gives no response, while less intense UV light increases conductivity 4 orders. The response cut-off wavelength is at about 370 nm.

====Simplifying complex nanowires====
Complex oxides with superconducting, ferroelectric and ferromagnetic properties can not easily be made as nanowires by conventional methods. MgO nanowires must be used as templates. Firstly, single crystal orthogonal MgO nanowires are grown on single crystal MgO substrate. Oxygen is flowed over Mg3N2 at 900 degrees as precursor for VLS, using Au catalyst. After the MgO nanowires have been made, the complex metal oxide is deposited by pulsed laser deposition to create a shell on the surface of MgO wires. Another approach to simplify complex nanowires is to use hydrothermal synthesis. This can be used to make PbTiO3 nanorods which is a ferroelectric material and potentially useful as building blocks in nanoelectrochemical systems. (Amorphous PbTiO(3-X)(OH)2X precursor is mixed with sodium dodecyl benzene sulfonate surfactant and reacted at 48 h at 180 degrees at alkaline conditions in the presence of a substrate.) The nanorods obtained have a squared cross section 35-400 nm, and up to 5 um long. The rods grow in the (001) direction by self-assembly of nanocubes to anisotropic mesocrystals, which is ripened into nanorods.

====Electrospinning====
Electrospinning is nanofiber extrusion in a capillary jet. A polymer solution or polymer sol-gel pass through a high voltage metal capillary to create a thin charged stream. The stream undergoes stretching, bending and solvent evaporation. The charged nanofibers are driven to ground electrodes. The dimensions of the fibers depend on solvent viscosity, conductivity, surface tension and precursor concentration. The collector electrodes can be patterned to make organized arrays between them by electrostatic self assembly. The electrodes can be grounded simultaneously or sequentially. This can be used to make single layer or multilayer nanowire architectures.

====Hollow nanofibers by electrospinning====
Hollow nanofibers can be made by co-axial double capillary electrospinning that creates heavy mineral oil core with inorganic polymer around (Ti and PVP). The core-shell nanofibers are collected on an aluminum or silicon substrate and hydrolyzed. The oily core can be extracted with octane, which creates nanotubes with amorphous TiO2 + PVP. To crystallize TiO2 and oxidate PVP, the tubes can be calcined in air at 500 degrees.

====Dual electrospinning====
A side by side spinneret can be used to make bicomponent fibers. Ex: two solutions containing TiO2/SnO2 are simultaneously jetted. This is calcined. A heterojunction of SnO2/TiO2 can create devices with extremely high quantum efficiency and photocatalytic activity for treatment of organic pollutants in water and air.

Dette mangler:
* Carbon nanotubes (sections 5.41, 5.42, 5.44, 5.45-5.48 and lecture notes)
** What are carbon nanotubes? Be able to describe the three different structures they can have and how their properties are different.
** Be able to describe briefly (basic principles) at least two of the three main methods used to synthesize carbon nanotubes
*** Arc discharge
*** Laser ablation
*** CVD
** How can the different structure nanotubes be separated from each other and from other carbon particles.
** Be able to say something about their properties
*** Mechanical
*** Electrical
*** Chemical
** Know some about carbon nanotube chemistry (reactivity on the surface vs the ends etc.)
** Aligning of carbon nanotubes
*** Evaporation induced self-assembly
*** Patterned hydrophilic SAM on substrate – carbon nanotubes will assemble only on the hydrophilic patches.
*** Alignment by pre-existing patterns
**** Perpendicular to substrate
**** Parallel to substrate
*** AC/DC electric fields
** Applications of carbon nanotubes
*** Sensors
*** Strengthening of materials (composites)
*** Added to materials to improve conductivity

=== Kapittel 6: Nanocluster Self-Assembly ===

====Capped nanoclusters====

A capped nanocluster is a nanometer scale particle with well-defined positions of the constituent atoms. They nucleate from atoms and enter a size range where they behave electronically as molecular nanoclusters. As the number of atoms increases further, they cross over into the nanoscale size domain where quantum size effects dominate, they become quantum dots. A capped nanocluster has a monolayer of a capping ligand on the surface, which can be a polymer or an alkane thiol (if the surface is silver or gold) or some other molecule with an end group that will bind to the surface of the nanocluster. The capping molecules will prevent further growth of the nanocluster. Capping groups serve multiple purposes:
*Change solubility properties
*Enable size-selective crystallization
*Surface functionalization
*Protect nanoclusters from luminescence or charge-carrier quenching

====General principles for synthesis of capped nanoclusters (arrested nucleation and growth)====

One general synthesis method is the arrested nucleation and growth synthesis. The basic idea is to rapidly create a large number of nucleated seeds (of desired materials) and then allow these to grow at the same rate below supersaturation conditions. This method can be described by the following steps:
* Desired precursors are added to a solution containing a proper capping agent, which is held at an intermediate temperature (200-400 °C depending on the materials. Temperature needs to be high enough to overcome the activation energy for the reaction.).
* Precursors need to be added at an amount that is over the saturation point for the materials in that specific solution.
* Materials will rapidly nucleate (precipitate) and start growing. Once the first molecules have reacted and created a small seed, the energy required for further growth is smaller than the initial activation energy. The nucleated seed can therefore continue to grow below the saturation concentration for the precursor materials.
* Once the nanoclusters reach a certain size range, which may vary from one material to the other, the capping agents will adsorb on the surface of the nanoclusters and prevent further growth. The nanoclusters that are formed will not all have the same diameter, but a range of different diameter clusters will be formed. This can be due to for example concentration gradients in the reactor or reaction medium.

====Minimize size dispersity by confining the reaction space====

The size of the capped nanoclusters can be controlled by growing them in nanowells made by the methode in figure x. The nanowells are obtained by patterning a silicon wafer with a layer of well-ordered microspheres. By pressing the microspheres against a the wafer and at the same time melt the surface of the wafer with a pulsed laser molten silicon will flow into the voids between the spheres. The size of the nanowells depend on the size of the spheres, the energy density of the laser pulse and applied mechanical pressure, while the size of the crystals depend on the well volume and concentration of the reactants. The crystals can be removed by ultrasound. The downside of the approach is that the amount of nanocrystals obtained will be quiet small.

====Tuning properties through physical dimensions rather than chemical composition (QSE)====

When electrons are confined in space the size invariant continuum of electronic states of bulk matter transformes into size dependent discrete electronic states in a quantum dot. At the 1-5 nm length scale, which is the CdSe nanocluster size range, the parent continuous electron bands of the bulk semiconductor becomes discrete. The nanoclusters then belong to the quantum size regime, and the properties begin to scale in a predictable fashion with size. By looking at the Schrödinger wave equation it can be seen that there is a blue quantum size effect shift in the energy of the first exciton band or band gap that scales with the reciprocal of the square of the radius of the nanocluster. The wavelengths absorbed change, and the colors of the nanoclusters can be alterd from yellow to red, by changing the physical size of the clusters

====How can different phases occur for smaller size particles?====

Similar to temperature and pressure, phase transformations in bulk materials are dependent on size. Phase transitions that are prohibited or slowed down by activation energies in the bulk can occur much more readily in nanocrystals of same material. Because of the small size of the crystal the influence of bulk and surface-free energies are different from in a bulk matter. Phase transformations show a distinct dependence on nanocrystal size. It can be shown that phase of nanoclusters can change just by exposing them to a different chemical environment at room temperature.

====Makeing nanoclusters water soluble====

Why? Water is cheap, widely available and use of it avoides the disposal o organic solvents, which can be quiet harmful for the environment. (Green chemistry). You can use the same principles as for the SAM surface chemistry. A hydrophilic SAM is made by choosing a hydrophilic group such as a carboxylate, ammonium or oligo ethylene glycol. In the case of a gold nanocluster, a thiol with a terminal carboxyl group gives an ionized, water loving carboxylate when in aqueous solution. Hydrophobic nanoclusters can be wrapped by amphiphilic polyers. The polymer coating is stabilized by partially cross linking the anhydride gropuos with bis(6-aminohexyl)amine. Can also coat with silica. Often, the resulting crystals bear a surface charge, which allows their use in electrostatic layer-by-layer deposition.

====Separation of nanoclusters by size using using a non-solvent and centrifugation====

Nanoclusters can be dissolved in toluene and by gradually adding a non-solvent (e.g. acetone) the nanoclusters will precipitate. The largest clusters precipitate first. Every time a bit of acetone is added the solution is centrifuged and the precipitate collected. The result is highly monodisperse nanoclusters collected in each fraction.

====Superlattice====

A superlattice is a material with periodically alternating layers of several substances. Such structures possess periodicity both on the scale of each layer's crystal lattice and on the scale of the alternating layers.

====Assembling of superlattices====

A superlattice can be assembled by means of these techniques:
*Tri-layer solvent diffusion crystallization - Three immiscible solvents are arranged to form separate layers in a test tube. Bottom layer →capped CdSe nanoclusters dissolved in toluene. Middle layer →buffer layer of 2-propanol selected for poor solvent properties wrt the nanoclusters. Top layer →non-solvent for the nanoclusters such as methanol. The process involves slow diffusion of the nanoclusters from the toluene bottom layer and the methanol from the top layer into the buffer layer. The change in solvent properties causes a slow and controlled nucleation and growth of capped CdSe nanocluster crystals.
*Sedimentation –
*Evaporation induced self-assembly – Strong capillary forces in an evaporating water meniscus drives the nanocomponents into close-packing.
*Langmuir-Blodgett – A dilute monolayer of capped silver nanoclusters is spread on an air-water interface. Using Langmuir – Blodgett “equipment”, this monolayer can gradually be compressed until a compact monolayer is formed.

====Gjenstår====

*Why do we want to make superlattices? (change of properties, properties of superlattice does not necessarily equal the sum of the properties of the individual constituents)How can capping agents (different type and length) affect the properties of a superstructure? (section 6.15)Alloying core-shell nanoclusters

* Nanocluster-polymer composites
** What is it?
** How can it be used for down-conversion of light?
* Be able to give one or two examples of how different size nanoclusters labeled with different fluorescent molecules can be used in biology.
* What is a tetrapod and what is the main priciples of the synthesis behind the tetrapod?
** Using a material that has two common crystal polymorphs where growth of one over the other can be controlled by synthesis temperature.
** Use of a long chain molecule which selectively binds to specific facets of the structure and hinders growth in those directions. This confines the growth of the material to one spatial dimension.
* Photochromic metal nanoclusters (section 6.31)
** Be able to explain what happens to silver nanoclusters embedded in a titania matrix when it is exposed to either UV-light or visible light.
* What is a buckyball and what can it be used for? What special properties does it exhibit? (Do not need to know specific details of synthesis or assembly techniques.)

=== Kapittel 7: Microspheres – Colors from the Beaker ===

Nå ferdig med så mye som forfatteren greide, men finn gjerne ut resten og del det med alle!

====What is a photonic crystal? ====
*It is a crystal consisting of a material with high dielectric contrast and periodicity at the light scale
*Vullums definition: Natural gratings that diffract light are based on dielectric lattices with periodicity at optical wavelengths. 3D optical diffraction gratings have dielectric lattices that are geometrically complimentary.
*1D PC (planes) is a crystal which only inhibit light to travel in one direction
*2D PC (rods) inhibits light to travel in two directions
*3D PC (spheres) inhibits litght to travel in any direction and has a full photonic band gap (PBG), whilst 1D and 2D only have so called stopgaps

====Photonic Crystal defects====
*Point defects: Holes, missing spheres, in a 3D PC can trap light inside the crystal
*Line defects: Many holes which make a line can guide light through a crystal
*Plane defects: A missing plane or a defect in a plane can make photons slip through to the other side. Planes consisting of another type of material can cause the perfect reflection curve of a PBG-crystal to drop at certain wavelengths depending on the size of the defect.

====Making defects====
*Writing defects: Multiphoton laser writing using a confocal optical microscope induced polymerization of an organic monomer in the colloidal crystal to create small line inside the photonic lattice. Then you treat the crystal and remove the polymer. In reversed opal structures you can use laser microwriting where you attach a laser to a scanning optical microscope which again changes the phase (which again changes the refractive index) of the inverse opal by annealing.
*Synthesizing planar defects: Introducing a dense layer or a layer with spheres of a different size than the surrounding colloidal crystal. Dense layers can be introduced by either CVD, electrolyte LbL, PDMS-stamps or maybe another deposition technique. The process consists of growing a photonic crystal, then using electrolyte LbL-deposition or PDMS-stamp make a thin film before making another photonic crystal. It's like a sandwich.

====Manipulating photonic crystals usage====
*Color of the structure is partially determined by the size of its spheres, where small spheres give blue/purple colors and larger spheres goes towards red (from yellow to green and then red).
*Non-close-packed polymerized colloidal crystalline arrays can be made to swell or shrink by external influence. As the diffraction colors of the crystal depend on the spacing between microspheres you can place a hydrogel between the spheres and this gel will swell or shrink depending on external environments. This will make the color change when the gel shrinks or swells as the pH, temperature, water concentration or ionic strength changes.
*The dielectric constant can be changed by changing the material, the structure of the crystal ''or something else that others edit in here''
*An example: Removal of cation causes a hydrogel to shrink, which can be detected at even very small concentrations. The order of cation complexation determines how sensitive the sensor is. Cation selectively binds covalently to the polymer network, sol-gel or hydrogel.

====Core-corona, core-shell-corona and multi-shell microspheres====
Core-corona and core-shell-corona can be made by both re-growth and one stage growth as multishell microspheres probably is better off being made by the re-growth process. The purpose of making these spheres is to put a lot more functionalities into just one sphere. The shells can be fluorescent, magnetic , photoactive, semiconductive, sacrificial or something else pulled out of a hat.

====Growth synthesis====
*One stage: Reagents are mixed and the microspheres are obtained in solution by a nucleation and growth
*Re-growth: First a sees is produced. The seed is then allowed to grow in several steps. Surface tension controls the shape, where low surface tension gives spherical particles.

====Self assembly of photonic crystals====
*Sedimentation (be able to explain in more detail): Use Stokes equation to make the radius as you want it by changing the viscosity very slowly.
*Electrophoresis '''– noen som veit?'''
*Hydrodynamic shear '''– noen som veit?'''
*Spin coating '''– noen som veit?'''
*Langmuir-Blodgett layer-by-layer (be able to explain in more detail) '''– noen som veit?'''
*Parallel plate confinement: Force spheres to assemble by placing them between two parallel plates and slowly moving one plate closer to the other. Important with slow movement to prevent defects. This can be done both dry and in fluid. It is necessary to increase density and viscosity of solvent so that settling occurs slowly in order to control structure and shape, and to avoid defects.
*Evaporation induced self-assembly, EISA (be able to explain in more detail) Capillary forces drive the assembly of spheres in a solution as you remove a wetting plate out of the solution. These the need to be dried and this can cause cracking. Vertical substrate is placed in a dispersion of microspheres. As solvent evaporates, the microspheres are driven by convective forces (forces from movement in solvent towards wall, surface, water meniscus) to the solvent-air meniscus. The layer thickness is determined by the diameter of the microspheres, their volume, concentration and the wetting properties of the solvent on the substrate.

====Colloidal aggregates====
*CA are made either by templated pattern in a surface or by aggregation in a homogeneous emulsion.
Emulsion-way:
*They are disperse microspheres in a solvent such as toulene.
*Add dispersion to solution of surfactant and water
*Stir or shake to get emulsion
*Toulene evapourates and as toulene droplets shrink, microspheres are pulled together in a stable cluster through capillary forces.
Photonic crystal marbles:
*Aqueous dispersion of microspheres is forced, under pressure, through a small syringe in the presence of an electric field. Surface charge on the liquid jet make it break into homogeneously sized spherical particles. Each droplet (sphere) contains a preset quantity of microspheres.
*Electrospraying - '''noen forslag?'''

====Bragg-Snell law====
*The reflected light has a wavelength depending on Bragg's and Snell's law. This then tells us that the wavelength of the first stop band is proportional to distance between the lattice plains. This gives that the longer the distance between the plains (bigger microspheres) gives longer wavelength.
<math>\lambda_{c(hkl)} = 2d_{hkl}\sqrt{\langle \epsilon \rangle - sin^2{\theta}} </math>
der <math>\langle \epsilon \rangle</math> is the effective dielectric constant of the colloidal crystal.

====Cracking====
This happens when the thin hydration layers around the crystal spheres dry out. This creates capillary stress and thermal expansion. To prevent cracking you can dry the crystal slowly, use hydrophobic spheres. Methods for preventing this is:
*<math>SiCl_4</math> reacting within the hydration layer to create a <math>SiO_2</math> layer between the spheres. Rehydrate to form multiple layers. Advantages as good control of layer thickness as it can be controlled/monitores by optical diffraction as a thicker layer res-shifts the diffraction peak.
*Necking at room temperature using vapor phase alternating chemical reactions
*Heat treatment before assembly. This may require pretreatment before assembly to give desired surface charges. Redeisperse and crystallize without volume contraction

====Liquid crystal photonic crystal====
Neither a liquid nor a crystal, but an intermediate state of matter, so called mesophase. Lacks the long range order of the crystalline state and does not exhibit the randomness of the liquid state.
*Themotropics are LCPC which consists of melted anisotropical shapes (rods or discs) where they ar partially alligned. The order of the components in the LCPC is determined and changed bu the temperature.
*Two groups of thermotropics are ''nematic'', where the molecules have no positional order, but they have a long-range orientational order, and ''discotic'', which consists of disc-shaped particles that can orient in a layer-like fashion.
*By applying electric- and/or magnetic fields the small crystals in the liquid will align after the applied fields and this can control the transparency of the film or whatever you have made out of this LCPC. Eksample of usage is privacy/smart windows.
*By using LCPC with an inverse opal you can tune the color by changing the temperature or applying a field of some sort.
*LCPC is thought to be used as tunable photonic crystal device and liquid crystal-colloidal crystal switch.
How can the colors of such a crystal be altered and what can it be used for?

=== Reactions that you need to know: ===
* Reaction of alkane thiolate with gold. Important to know that alkane thiols have a specific affinity for gold (also keep in mind that silver and gold have very similar properties).
* Reaction that occurs when during anodic oxidation of Al to produce porous alumina membranes.
* Reaction that occurs when silica microspheres are formed from Si(OEt)4 and water (section 7.9): <math>Si(OEt)_4 + 2H_2O \rightarrow SiO_2 + 4EtOH</math>

== Eksterne linker ==
*[http://www.ntnu.no/portal/page/portal/ntnuno/AlleEmner?rootItemId=22934&selectedItemId=31007&emnekode=TMT4320 NTNUs fagbeskrivelse]
*[http://www.ntnu.no/studieinformasjon/timeplan/h08/?emnekode=TMT4320-1&valg=emnekode&bokst= Timeplan Høst08]

[[Kategori:Obligatoriske emner]]
[[Kategori:Fag 5. semester]]
[[Kategori:Fag]]

TMT4320 - Nanomaterialer

2008-12-15T08:28:46Z

Audunnys: /* Kapittel 4: Nanocontact printing and writing */ Endret formatering for å gjøre det mer konsistent med resten av siden

{{Infobox
|Fakta høst 2008
|*Foreleser: Fride Vullum
*Stud-ass: ?
*Vurderingsform: Skriftlig eksamen
*Eksamensdato: 18. desember
}}

{{Infobox
|Øvingsopplegg høst 2008
|* Antall godkjente: 6/12
* Innleveringssted: Utenfor R7
* Frist: Tirsdager 16:00 (?)
}}

Emnet skal gi en innføring i grunnleggende kjemisk prinsipper for å lage nanomaterialer. Stikkord: "Self-assembled" monolag ([[SAM]]) og hvordan disse kan formes ved myk litografi og "dip pen" nanolitografi, syntese av tredimensjonale multilag strukturer. Tynne filmer ved kjemisk gassfase deponering. Syntese av nanopartikler, nanostaver, nanorør og nanoledninger. Våtkjemiske syntese av oksidbaserte nanomaterialer. "Self-asembly" av kolloidale mikrokuler til fotoniske krystaller, porøse nanomaterialer, blokk-kopolymere som nanomaterialer. "Self assembly" av store byggeblokker til funksjonelle anordninger.

== Oppsummering av pensum ==
Her vil det etterhvert vokse fram et lite kompendium i faget. Dette følger i utgangspunktet pensumlista som gjelder for høsten 2008.
===Chapter 1: Nanochemistry Basics ===
Not terribly important.

===Chapter 2: Soft Lithography===
====Self-assembled monolayers (SAMs)====
*The typical example of a SAM is a layer of alkanethiols on a gold substrate.
*The S-H bond is cleaved on the gold surface and an Au-S covalent bond is formed.
*The alkanethiols are tilted off-axis from the normal. The angle depends on the surface. (30 ° for a {111} gold surface, 10 ° for a silver surface).
*The end group on the alkanethiols can be tailored to achieve different monolayer properties.

====PDMS stamp====
* PDMS = PolyDiMethylSiloxane
* A master (casting) of the stamp, with the desired pattern, is made with lithography. The master is silanized and made hydrophobic so removing the stamp becomes easier.
* Liquid PDMS is then poured into the master, after which it is cured and a finished PDMS stamp is removed from the master.
* The critical dimensions of the pattern are limited by the lithography techniques used, and for [[photolithography]] the wavelengths of the light used to expose the [[photoresist]] limits the dimensions. Typical CDs given are, for lateral dimensions within the range of 500nm-200µm, and for the height of patterns 200nm-20µm.
* The PDMS stamp can be dipped in alkanethiol solutions (or solutions of other molecules, collectively known as "chemical ink") and be stamped onto surfaces
* PDMS stamps work on both planar and curved surfaces
* For the stamp to properly print a pattern onto a surface, the molecules need to adhere to the stamp from the solution, but needs to adhere more strongly to the surface to be printed on.

====Hydrophilic / Hydrophobic stamps====
* The endgroup/terminal group on the alkanethiols (or other molecules used) determine the properties of the monolayer
* By introducing a wetability gradient or abrupt changes in wetability, different effects can be obtained
** Square drops, by having checkerboard square patterns of hydrophobic/hydrophilic monolayers, and condensating a vapor onto the surface
** Drops "running uphill" by having wetability gradients
====Printing thin films====
* As long as the adhesion between the chemical ink and the substrate is stronger than the adhesion between the ink and the stamp, printing thin films is no problem
* Metal thin films can be evaporated onto the stamp (evaporation gives homogenous and directional coatings, not covering the side walls on the stamp) and printed onto a substrate that has been primed with a SAM with exposed thiol groups (adheres strongly to the metal layer)
* This is a very gentle technique for metal film depositing, good for making contacts on fragile layers. Also good for making 3D stuctures by printing multiple layers.
====Electrically conducting SAMS====
* Electronic devices will always need to make electrical contact with SAMs
* Other, less gentle methods of metal deposition than printing with PDMS stamps (sputtering, CVD, etc) can cause the metal layer to penetrate the SAM
* Morale: Use stamps to deposit metals on SAMs!
====Patterning by photocatalysis====
* Photocatalysis is used to remove parts of a SAM (making patterns)
* Titania can photocatalytically decompose organic molecules.
* A quartz slide patterned with titanium dioxide in the required pattern is pressed against a wafer with the SAM on it.
* The assembly is exposed to UV irradiation, triggering the degeneration of the (organic) SAM

===Kapittel 3: Building layer-by-layer===
====Electrostatic superlattices====
* Lbl multilayer films formed by alternate immersion in suspensions of opposite charges
* A primer layer with a charge adheres to the substrate. The substrate is then dipped in a solution of polyelectrolytes of opposite charge from the primer layer. Repeated with opposite charges.
* As the amount and identity of constituents of each layer can be controlled, a composition gradient can easily be constructed throughout the structure.
* Any species bearing multiple ionic charges can be layered.
* Can be applied to curved surfaces like microspheres, enables applications like hollow spheres with a semipermeable cap.

====Some applications====
* Electrochromics layers (change color when a potential is applied), used in "smart windows" for instance
* Construction of cantilevers for AFMs and similar equipment, using photolithography and lbl

====Analysis, measuring film thickness====
* Optical spectroscopy: If the substrate is transparent, and the film absorbs light at a certain wavelength, the film thickness can be found by monitoring the optical absorption as a function of number of layers. A dye can be introduced to ensure absorption. Easy to perform but hard to interpret - must know the observation area and extinction coefficient of the absorbing group.
* Ellipsometry: Film is probed by polarized light, and change in polarization in the reflected light is measured. This can be used to find the refractive index, thickness, roughness and orientation of a thin film. Ellipsometry works with films much thinner than the wavelength of light - down to atomic layers.
* Quartz crystal microbalance (QCM): Quartz (piezoelectric) in an alternating electric field contracts/expands with a characteristic oscillation frequency. When mass is added to QCM the frequency decreases. This allows real-time thickness measurements. Works well for hard materials like metals and ceramics, but not for viscoelastic materials.
* Direct techniques: Label each layer with heavy metal atoms and image by TEM. Alternately, deposit a thin gold layer on top of the surface and image cross section by TEM.

====Non-electrostatic lbl assembly====
* Lbl doesn't need electrostatic bridges - can use hydrogen bonding, ligand-receptor interactions or even covalent bonds.
* Example: DNA (adenine-thymine and guanine-cytosine bridges)
* Hydrogen bonds can be broken again by changing the pH, or can be strengthened by UV irradiation

====Low-pressure layers====
* Molecular beam epitaxy (MBE): Performed in a vacuum, sources of constituents (elemental) are heated, and a thin film alloyed from the constituents is deposited. The result is a homogeneous crystal. The substrate should have a similar lattice constant to that of the layer deposited.
* Chemical vapor deposition (CVD): Volatile precursors are introduced in gas phase in a low-pressure reactor chamber. Argon gas is used to dilute the precursor gas to achieve optimal pressure and concentration. The substrate is heated, and the precursor decomposes at the surface.

====Lbl self-limiting reactions====
* Atomic layer deposition: Similar to CVD, but usually carried out in solution.
* Iterative saturating reactions.

=== Kapittel 4: Nanocontact printing and writing ===

''Dag H. jobber med kap.4''
====Soft lithography and microcontact printing ====
* Sub 100 nm Soft Lithography: Previous chapters has covered printing on 10.000-100 nm scale. Need for further miniaturization because of demand for more power, efficiency, and density. This can be done by manipulating PDMS stamp, Dip Pen Nanolithography (DPN),Whittling Nanostructures or by Nanoplotters

**Manipulating PDMS stamp: Manipulating PDMS stamp can be done in various ways, and seven of the basic ideas will now be explained. Illustrating pictures are in the book and in foils. 1) Compress the stamp, mold to get a new stamp with inverse pattern, peel off and repeat. 2) Apply force perpendicular onto stamp when on substrate. The areas in contact with substrate will then increase, and spaces in between gets smaller. 3) Size reduction by reactive spreading some sort of ink when in contact with substrate. The contact time + properties of the ink decide to which degree the ink spreads. 4) Size reduction by extraction of inert filler (just like retracting water from a sponge). 5) Size reduction by swelling the stamp in toluene. 6) Size reduction by stretching stamp so that dimensions get smaller in one axis and larger in another. 7) Size reduction by double-printing. Limitations:Deformation can be a shortcoming if care is not taken with the dimensions of surface relief pattern in the stamp as this can give unwanted deformations. Quality of printed pattern will not be good. Defect-free contact printing is restricted to a certain range of height-to-width ratios. If ratio is outside 0,2-2, the roof of the grooves on stamp will touch the substrate.Too high perpendicular force on stamp has the same effect, but overpressure can also be used to form new patterns such as micron scale discs and rings of ferromagnetic core-shell nanoparticles. Nanoparticles are then transferred to PDMS stamp by Langmuir-Blodgett technique (chapter 6) and then into contact with Au-coated silicon substrate. Low pressure => discs, high pressure => rings.

====Dip pen nanolithography====
* Alkanethiols can be written on gold substrate with AFM tip. The alkanethiols are delivered to the tip via a water meniscus, and this can be adapted to suit other surface chemistries. The result is 10 nm fine patterns of molecules (biomolecules, polymers etc.) on metals, semiconductors and dielectrica.
* Sol-gel DPN:patterning of solid-state materials. Nanoscale patterns are written using a metal oxide sol-gel precursor in a solvent carrier. The sol-gel precursors are hydrolyzed to metal oxide by use of atmospheric moisture and water meniscus at the tip-substrate interface. pH, substrate temperature and post treatment can be varied.
*Enzyme DPN: A scanning microscope tip can be used to place an enzyme on a specific site on a biomolecule with nanometer presicion. This method leads to the possibility of bionanodegradable electronic and optical devices.
*Electrostatic DPN: Like thin films can be made of charged polyelectrolytes, an AFM tip can "draw" lines or structures of charged polymers with for example specific electrical properties to build nanoscale electronic devices.
*Electrochemical DPN: The meniscus that forms between surface and tip is used as a nanochemical reactor. Electrochemical deposition can be done by applying voltage between tip and substrate. Ex: making platinum lines can be made by reducing Pt salt at -4 V, and silica lines can be made by oxidation of silicon surface at +10 V.

====Whittling of nanostructures (section 4.19)====
* Only be able to explain basic principle
**The spatial extent of SAMs can be reduced by so-called "whittling". Whittling is an electrochemical desorption process where a voltage applied will cause ligands to desorbate. It has been found that the larger the accessibility of a molecule, the lower the desorbation voltage is (fig. 4.22)

====Nanoplotters and nanoblotters====
* What are these and what can they be used for?
**Nanoplotter: Parallel cantilevers write SAM nanopatterns simultaneously.
**Nanoblotters: An PDMS inkwell has been created to deliver ink to the nanoplotter cantilever tips (fig. 4.26)

====Combinatorial libraries====
* Be able to explain the basic principle and how it is used to find new and improved materials.
**DPN can be used to put different materials together in the research of new material composition. With DPN, many different combinations can be made with small material amounts used.

=== Kapittel 5: Nano-rod, nanotube, nanowire self-assembly ===

''Emily skriver på denne. Håper folk retter opp dersom de finner feil, og legg gjerne til flere ting:)''

====Templating nanowires and nanorods====
Templates can be used for making solid nanowires/nanorods/nanotubes of controlled sizes. Examples of templates are alumina, silicon, zeolites and lipid bilayers.

====Making modulated diameter silicon templates====
A p+ doped silicon wafer is put in aqueous HF and an oxidizing potential is applied. The result from this is nanoporous silicon with random network pores. The diameter of the pores can be tuned by controlling the voltage or current. The higher the current is, the wider the channels get. If perfectly ordered pores are desired, the wafer can be lithographically patterned with regular array of nanowells in advance. The electric field will then be focused at the tip of these wells.

====Making porous alumina membranes====
Porous alumina membranes can be made by anodic oxidation of lithograpically embossed aluminum sheet in phosphoric or oxalic acid electrolyte (the almunium sheet functions as the anode).

<math> 2Al + 3PO_4^{3-} \rightarrow Al_2O_3 + 3PO_3^{3-}</math>

The residual Al and Al2O3 is removed by mercuric chloride and phosphoric acid. The diameter is controlled and can be 20-500nm. Mechanisms that give ordered channels are the fact that electric fields created by applied voltage repell each other, and that we have volume expansion when aluminum becomes alumina. Temperature is also a factor that affects the reaction.

====Modulated diameter gold nanorods====
With use of silicon template. The back surface of the silicon membrane is subjected to a local thermal oxidation which formes silica. The silica is then removed by HF. By proceeding with a KOH anisotropic etch on the same area, and a dip in HF, the pores in the template are opened. A gold sputter deposition can then be done on the backside. This gold layer acts as a catalyst for continued electroless deposition of gold. Finally, the silicon membrane is etched away, and the gold nanorod dispersion can be collected.

====Modulated composition nanorods/nanobarcodes====
Modulated composition nanorods can be made by electrochemical deposition of different metal segments within the channels of an alumina template (electrodeposition will be better explained in the following section). Any type of material that can be electrodeposited can be used in the nanobarcodes. One synthesis route is to evaporate thin metal film to one side of an alumina membrane. This metal film function as the cathode, and metal deposition begins at the bottom. Bath can be switched between different metal salts to grow several segments. The alumina membrane is dissolved using sodium hydroxide, and the metal backing is dissolved using acid.

Nanobarcodes can be used to tag molecules in analytical chemistry and biology. Characteristic of metals are optical reflectivity, which means that different segments of the barcode nanorod can be distinguished in optical microscopy. Probe molecules must be anchored to different segments, and the rods must be dispersed in analyte containing target molecules which bear a luminescent label. By molecular recognition, the target molecules bind to the probe molecules (ex: ligand-receptor binding for biological applications). By looking at the segments that light up, it can be decided which molecules excist in the solution.

====Electroplating/electrodeposition====
The part to be plated is the cathode, while the anode is made of the material to be plated. Both components are immersed in electrolyte solution. The dissolved metal ions (cations) are reduced at the interface between the solution and the cathode when current is applied.

====Electroless deposition====
Spontaneous reduction of a metal (ex: copper or silver) from a solution of its salt. A reducing agent (which acts as the source of the electrons) is required, but no current is required. The surface acts as a catalyst to allow the deposition to proceed (ex: the gold sputtered layer in making the gold nanorods in alumina).

====Nanotubes====
Nanotubes can be made by partial filling of the membranes radially. This means that a uniform coating must be deposited on the pore walls. One way to do this is by letting fluid spontaneously wet inside the template pores. Fluids that can be used are molten polymers, polymer solution or sol-gel preparation. These are coated onto template using capillary forces resulting from small diameter channels with a large available surface. Solidification of these fluids can be done by heating, cooling, waiting or using a catalyst. With this method it is difficult to control the wall thickness.
Another way to make nanotubes is by using LbL growth procedure inside the pores. This can be done by CVD of gas phase species, solution phase ALD or LbL electrostatic assembly. Wall thickness is easier to control with these methods.
Finally, the membrane is dissolved. It can also be deposited other material inside the remaining void to get coaxially coated rod or wire.

Nanotubes can also be made from LbL electrostatic coating of nanorods. The rods can be dissolved afterwards, and will leave a closed-ended tube. This method is applicable to any material that can be coated onto a nanorod and not be affected by the etching step.

====Magnetic Nanorods====
Magnetic metals such as iron, cobalt or nickel can easily be deposited into membranes. Magnetic properties are direction and size dependent. If the thickness of the magnetic segments on a nanorod is smaller than the diameter, they will self assemble into 3D bundles. If the thickness is bigger than the diameter, they will align in chains of rods. If the thickness is the same as the diameter they will be in random aggregates. Magnetic nanorods can be used for separation of molecules. A tri-segmented Au-Ni-Au nanorods can be used as affinity template for histidine- tagged proteins. Nickel selectively captures the labeled protein, and a magnetic field can be used to separate the rod with the captured protein from the rest of the solution of biomolecules. After this, the proteins can be chemically released from the magnetic nanorod. The gold segments must be in the rod to protect nickel from the etching during dissolution of alumina template after electrodeposition, and also to prevent aggregation.

====Making Single Crystal Nanowires====
Single crystal nanowires can be made by Vapor-Liquid-Solid (VLS) synthesis, Supercritical Fluid-Liquid-Solid (SFLS) synthesis or by Pulsed laser deposition.

*VLS Synthesis
A catalyst droplet first melts, then becomes saturated with precursors. Elements extrude out of the catalyst droplet as a single crystal nanowire in a furnace where the temperature is controlled to maintain liquid state of the catalyst droplet. Micrometer length with diameter less than 10 nm can be done. The diameter is controlled by the diameter of the catalyst droplet, and growth stops when the nanowire pass out of the hot zone, if the precursor is depleted or the catalyst droplet no longer is in liquid state. One example is to use laser ablation of Fe-Si target to create a Fe-Si nanocluster catalyst droplet. The Si nanowire grow with the (111) lattice planes perpendicular to the growth axis due to epitaxy at the nanocluster-nanowire interface. Doping can be done by controlling stoichometry of the target, or by introducing dopant into gas phase during growth.

*SFLS Synthesis
Similar to VLS, but used for high-eutectic temperature combinations. The solvent is pressurized above its critical point to reach higher temperatures. Can be applied to semiconductor/metal combinations (Ga/GaAs, In/InN) with eutectic temperature below 600 degrees. Au is used as catalytic seed, and diameter depends on this.

*Pulsed laser deposition
?????? laser ablation?????

====Nanowires branch out====
Can create branched nanowires by VLS growth. The catalytic nanoclusters from solution placed on specific point on the body of a parent nanowire before growth. The process can be repeated for a hyper-branched construction. This could be the future development of nanowire electronics in 3D.

====Quantum Size Effects (QSE)====
QSE appear when the particle size becomes smaller than the exciton size for the material (about 5 nm for silicon). Exciton is a bound state of an electron and an electron hole in an insulator or semiconductor, which is defined by the energy gap between the valence band and the conduction band. Color of the emitted light is determined by the size of gap energy. Gap energy increases with decreasing nanowire diameter. This can be used for LEDs and lasers. Both quantum confined nanoclusters and nanowires show QSE, but anisotropy make them different. Luminescent nanocluster emits plane-polarized light, while nanorod exhibits linearly polarized light.

====Alignment methods====
Alignment methods include electric field based alignment, microfluidic alignment and Langmuir-Blodgett technique.

*Electric Field Based Alignment
Apply voltage between two micropatterned electrodes to produce electric field. Charges within a nanowire in solution become polarized, creating an attraction between the electrodes and the nanowire. The electric field is quenched when the gap between the electrodes are bridged by a nanowire. This eliminates absorption of a second nanowire at the same electrodes. Metal spots can be evaporated onto insulator surface to focus the electric field.

*Microfluidic Alignment
A PDMS stamp with a series of parallel rectangular grooves is used for this purpose. The channels are aligned under a microscope with electrodes that have been previously patterned on a substrate (these will function as metal contacts for the conducting or semiconducting lines made by this method). A drop of nanowire suspension is flowed into the microchannels by capillary forces, and solvent evaporation aligns the wires at the edges of the channels.

*Langmuir-Blodgett Technique
A Langmuir film is first created when a small amount of insoluble liquid (amphiphile) is poured onto another liquid. The balance of surface tension forces determines the profile of the meniscus formed when a substrate is pushed into this liquid. If the substrate is hydrophobic it will experience deposition of the amphiphiles during immersion. If it is hydrophilic it will experience deposition during retraction. A nanowire array can be made by firstly compressing the interface to increase the surface density of nanowires (so they align parallel to each other), and then do a double dip. The second dip must be done so that the wires align normal to the previous once.

Application areas for these methods are in LED’s, transistors and in nanowire UV photodetectors.

====LED====
A LED is a two terminal device consisting of an n-doped and a p-doped semiconductor (eg. nanowires). To collect the doped nanowires into LED structure, voltage is firstly applied to one pair of electrodes, and then the second pair so that they lie in a cross. They can also be assembled by using the microfluidic approach. Light is emitted when electrons recombine with holes at the junction between the differently doped wires. Color of the emitted light depends on composition and condition of semiconducting material used. The LED can only conduct current in one direction. With positive voltage current flows. With negative voltage current is inhibited. The key for success is to achieve abrupt and uncontaminated junction between n and p doped wire. Efficiency can be improved by using core-shell-shell nanowire axial heterostructure. The greatest challenge is to make arrays of closely spaced junctions because the nanowires are so thin. This leads to the pitch problem, how to pack light sources into smallest possible area.

====Transistors====
A transistor can switch or amplify signals, and has three terminals (n-p-n). The n-type region attached to the negative end of the battery sends electrons into p-region, and the n-type region attached to the positive end slows the electrons down. The p-type region in the middle does both. Because of this, a depletion layer develops between the base and the emitter, and the base and the collector. The thickness of the layer is varied by the potential in each region. Active bipolar n-p-n transistor can be built from heavy and lightly n-doped nanowires crossing a common p-type wire base.

====How can nanowire transistors be used as sensors?====
Si nanowires are naturally coated with silica through VLS synthesis. This makes it easy for surface silanol groups to attach to the wire. If probe molecules are anchored to the surface silanols, highly sensitive real time electrically based sensors can be made. Low levels of chemical and biological species can be detected. Boron doped silicon nanowire is used as a FET. The wire is self assembled across electrodes (source and drain), and aminoethylsilane anchored to SiOH surface groups. The conductance of the wire changes with pH linearly due to protonation or deprotonation of the amine. An increase of the surface negative charge (deprotonation) attracts additional holes into the p-channel and the conductance is enhanced. The reverse action at low pH, an increase of surface positive charge causes protonation which repell holes from the channel. The conductance is decreased. Almost any type of molecule can be anchored to silica, so sensors can be designed to detect almost anything. For example, a biotin could be strapped to the surface amine groups to detect streptavidin.

====Nanowire UV photodetector====
The conductivity of ZnO nanowires is extremely sensitive to ultraviolet light exposure, which means that UV light can switch the nanowires between ON and OFF states. ZnO nanowires are highly insulating in the dark, but UV light with wavelength less than 380 nm decreases resistivity by 4 to 6 orders of magnitude. These nanowire photoconductors exhibit excellent wavelength selectivity. Green light (532nm) gives no response, while less intense UV light increases conductivity 4 orders. The response cut-off wavelength is at about 370 nm.

====Simplifying complex nanowires====
Complex oxides with superconducting, ferroelectric and ferromagnetic properties can not easily be made as nanowires by conventional methods. MgO nanowires must be used as templates. Firstly, single crystal orthogonal MgO nanowires are grown on single crystal MgO substrate. Oxygen is flowed over Mg3N2 at 900 degrees as precursor for VLS, using Au catalyst. After the MgO nanowires have been made, the complex metal oxide is deposited by pulsed laser deposition to create a shell on the surface of MgO wires. Another approach to simplify complex nanowires is to use hydrothermal synthesis. This can be used to make PbTiO3 nanorods which is a ferroelectric material and potentially useful as building blocks in nanoelectrochemical systems. (Amorphous PbTiO(3-X)(OH)2X precursor is mixed with sodium dodecyl benzene sulfonate surfactant and reacted at 48 h at 180 degrees at alkaline conditions in the presence of a substrate.) The nanorods obtained have a squared cross section 35-400 nm, and up to 5 um long. The rods grow in the (001) direction by self-assembly of nanocubes to anisotropic mesocrystals, which is ripened into nanorods.

====Electrospinning====
Electrospinning is nanofiber extrusion in a capillary jet. A polymer solution or polymer sol-gel pass through a high voltage metal capillary to create a thin charged stream. The stream undergoes stretching, bending and solvent evaporation. The charged nanofibers are driven to ground electrodes. The dimensions of the fibers depend on solvent viscosity, conductivity, surface tension and precursor concentration. The collector electrodes can be patterned to make organized arrays between them by electrostatic self assembly. The electrodes can be grounded simultaneously or sequentially. This can be used to make single layer or multilayer nanowire architectures.

====Hollow nanofibers by electrospinning====
Hollow nanofibers can be made by co-axial double capillary electrospinning that creates heavy mineral oil core with inorganic polymer around (Ti and PVP). The core-shell nanofibers are collected on an aluminum or silicon substrate and hydrolyzed. The oily core can be extracted with octane, which creates nanotubes with amorphous TiO2 + PVP. To crystallize TiO2 and oxidate PVP, the tubes can be calcined in air at 500 degrees.

====Dual electrospinning====
A side by side spinneret can be used to make bicomponent fibers. Ex: two solutions containing TiO2/SnO2 are simultaneously jetted. This is calcined. A heterojunction of SnO2/TiO2 can create devices with extremely high quantum efficiency and photocatalytic activity for treatment of organic pollutants in water and air.

Dette mangler:
* Carbon nanotubes (sections 5.41, 5.42, 5.44, 5.45-5.48 and lecture notes)
** What are carbon nanotubes? Be able to describe the three different structures they can have and how their properties are different.
** Be able to describe briefly (basic principles) at least two of the three main methods used to synthesize carbon nanotubes
*** Arc discharge
*** Laser ablation
*** CVD
** How can the different structure nanotubes be separated from each other and from other carbon particles.
** Be able to say something about their properties
*** Mechanical
*** Electrical
*** Chemical
** Know some about carbon nanotube chemistry (reactivity on the surface vs the ends etc.)
** Aligning of carbon nanotubes
*** Evaporation induced self-assembly
*** Patterned hydrophilic SAM on substrate – carbon nanotubes will assemble only on the hydrophilic patches.
*** Alignment by pre-existing patterns
**** Perpendicular to substrate
**** Parallel to substrate
*** AC/DC electric fields
** Applications of carbon nanotubes
*** Sensors
*** Strengthening of materials (composites)
*** Added to materials to improve conductivity

=== Kapittel 6: Nanocluster Self-Assembly ===

====Capped nanoclusters====

A capped nanocluster is a nanometer scale particle with well-defined positions of the constituent atoms. They nucleate from atoms and enter a size range where they behave electronically as molecular nanoclusters. As the number of atoms increases further, they cross over into the nanoscale size domain where quantum size effects dominate, they become quantum dots. A capped nanocluster has a monolayer of a capping ligand on the surface, which can be a polymer or an alkane thiol (if the surface is silver or gold) or some other molecule with an end group that will bind to the surface of the nanocluster. The capping molecules will prevent further growth of the nanocluster. Capping groups serve multiple purposes:
*Change solubility properties
*Enable size-selective crystallization
*Surface functionalization
*Protect nanoclusters from luminescence or charge-carrier quenching

====General principles for synthesis of capped nanoclusters (arrested nucleation and growth)====

One general synthesis method is the arrested nucleation and growth synthesis. The basic idea is to rapidly create a large number of nucleated seeds (of desired materials) and then allow these to grow at the same rate below supersaturation conditions. This method can be described by the following steps:
* Desired precursors are added to a solution containing a proper capping agent, which is held at an intermediate temperature (200-400 °C depending on the materials. Temperature needs to be high enough to overcome the activation energy for the reaction.).
* Precursors need to be added at an amount that is over the saturation point for the materials in that specific solution.
* Materials will rapidly nucleate (precipitate) and start growing. Once the first molecules have reacted and created a small seed, the energy required for further growth is smaller than the initial activation energy. The nucleated seed can therefore continue to grow below the saturation concentration for the precursor materials.
* Once the nanoclusters reach a certain size range, which may vary from one material to the other, the capping agents will adsorb on the surface of the nanoclusters and prevent further growth. The nanoclusters that are formed will not all have the same diameter, but a range of different diameter clusters will be formed. This can be due to for example concentration gradients in the reactor or reaction medium.

====Minimize size dispersity by confining the reaction space====

The size of the capped nanoclusters can be controlled by growing them in nanowells made by the methode in figure x. The nanowells are obtained by patterning a silicon wafer with a layer of well-ordered microspheres. By pressing the microspheres against a the wafer and at the same time melt the surface of the wafer with a pulsed laser molten silicon will flow into the voids between the spheres. The size of the nanowells depend on the size of the spheres, the energy density of the laser pulse and applied mechanical pressure, while the size of the crystals depend on the well volume and concentration of the reactants. The crystals can be removed by ultrasound. The downside of the approach is that the amount of nanocrystals obtained will be quiet small.

====Tuning properties through physical dimensions rather than chemical composition (QSE)====

When electrons are confined in space the size invariant continuum of electronic states of bulk matter transformes into size dependent discrete electronic states in a quantum dot. At the 1-5 nm length scale, which is the CdSe nanocluster size range, the parent continuous electron bands of the bulk semiconductor becomes discrete. The nanoclusters then belong to the quantum size regime, and the properties begin to scale in a predictable fashion with size. By looking at the Schrödinger wave equation it can be seen that there is a blue quantum size effect shift in the energy of the first exciton band or band gap that scales with the reciprocal of the square of the radius of the nanocluster. The wavelengths absorbed change, and the colors of the nanoclusters can be alterd from yellow to red, by changing the physical size of the clusters

====How can different phases occur for smaller size particles?====

Similar to temperature and pressure, phase transformations in bulk materials are dependent on size. Phase transitions that are prohibited or slowed down by activation energies in the bulk can occur much more readily in nanocrystals of same material. Because of the small size of the crystal the influence of bulk and surface-free energies are different from in a bulk matter. Phase transformations show a distinct dependence on nanocrystal size. It can be shown that phase of nanoclusters can change just by exposing them to a different chemical environment at room temperature.

====Makeing nanoclusters water soluble====

Why? Water is cheap, widely available and use of it avoides the disposal o organic solvents, which can be quiet harmful for the environment. (Green chemistry). You can use the same principles as for the SAM surface chemistry. A hydrophilic SAM is made by choosing a hydrophilic group such as a carboxylate, ammonium or oligo ethylene glycol. In the case of a gold nanocluster, a thiol with a terminal carboxyl group gives an ionized, water loving carboxylate when in aqueous solution. Hydrophobic nanoclusters can be wrapped by amphiphilic polyers. The polymer coating is stabilized by partially cross linking the anhydride gropuos with bis(6-aminohexyl)amine. Can also coat with silica. Often, the resulting crystals bear a surface charge, which allows their use in electrostatic layer-by-layer deposition.

====Separation of nanoclusters by size using using a non-solvent and centrifugation====

Nanoclusters can be dissolved in toluene and by gradually adding a non-solvent (e.g. acetone) the nanoclusters will precipitate. The largest clusters precipitate first. Every time a bit of acetone is added the solution is centrifuged and the precipitate collected. The result is highly monodisperse nanoclusters collected in each fraction.

====Superlattice====

A superlattice is a material with periodically alternating layers of several substances. Such structures possess periodicity both on the scale of each layer's crystal lattice and on the scale of the alternating layers.

====Assembling of superlattices====

A superlattice can be assembled by means of these techniques:
*Tri-layer solvent diffusion crystallization - Three immiscible solvents are arranged to form separate layers in a test tube. Bottom layer →capped CdSe nanoclusters dissolved in toluene. Middle layer →buffer layer of 2-propanol selected for poor solvent properties wrt the nanoclusters. Top layer →non-solvent for the nanoclusters such as methanol. The process involves slow diffusion of the nanoclusters from the toluene bottom layer and the methanol from the top layer into the buffer layer. The change in solvent properties causes a slow and controlled nucleation and growth of capped CdSe nanocluster crystals.
*Sedimentation –
*Evaporation induced self-assembly – Strong capillary forces in an evaporating water meniscus drives the nanocomponents into close-packing.
*Langmuir-Blodgett – A dilute monolayer of capped silver nanoclusters is spread on an air-water interface. Using Langmuir – Blodgett “equipment”, this monolayer can gradually be compressed until a compact monolayer is formed.

====Gjenstår====

*Why do we want to make superlattices? (change of properties, properties of superlattice does not necessarily equal the sum of the properties of the individual constituents)How can capping agents (different type and length) affect the properties of a superstructure? (section 6.15)Alloying core-shell nanoclusters

* Nanocluster-polymer composites
** What is it?
** How can it be used for down-conversion of light?
* Be able to give one or two examples of how different size nanoclusters labeled with different fluorescent molecules can be used in biology.
* What is a tetrapod and what is the main priciples of the synthesis behind the tetrapod?
** Using a material that has two common crystal polymorphs where growth of one over the other can be controlled by synthesis temperature.
** Use of a long chain molecule which selectively binds to specific facets of the structure and hinders growth in those directions. This confines the growth of the material to one spatial dimension.
* Photochromic metal nanoclusters (section 6.31)
** Be able to explain what happens to silver nanoclusters embedded in a titania matrix when it is exposed to either UV-light or visible light.
* What is a buckyball and what can it be used for? What special properties does it exhibit? (Do not need to know specific details of synthesis or assembly techniques.)

=== Kapittel 7: Microspheres – Colors from the Beaker ===

Nå ferdig med så mye som forfatteren greide, men finn gjerne ut resten og del det med alle!

====What is a photonic crystal? ====
*It is a crystal consisting of a material with high dielectric contrast and periodicity at the light scale
*Vullums definition: Natural gratings that diffract light are based on dielectric lattices with periodicity at optical wavelengths. 3D optical diffraction gratings have dielectric lattices that are geometrically complimentary.
*1D PC (planes) is a crystal which only inhibit light to travel in one direction
*2D PC (rods) inhibits light to travel in two directions
*3D PC (spheres) inhibits litght to travel in any direction and has a full photonic band gap (PBG), whilst 1D and 2D only have so called stopgaps

====Photonic Crystal defects====
*Point defects: Holes, missing spheres, in a 3D PC can trap light inside the crystal
*Line defects: Many holes which make a line can guide light through a crystal
*Plane defects: A missing plane or a defect in a plane can make photons slip through to the other side. Planes consisting of another type of material can cause the perfect reflection curve of a PBG-crystal to drop at certain wavelengths depending on the size of the defect.

====Making defects====
*Writing defects: Multiphoton laser writing using a confocal optical microscope induced polymerization of an organic monomer in the colloidal crystal to create small line inside the photonic lattice. Then you treat the crystal and remove the polymer. In reversed opal structures you can use laser microwriting where you attach a laser to a scanning optical microscope which again changes the phase (which again changes the refractive index) of the inverse opal by annealing.
*Synthesizing planar defects: Introducing a dense layer or a layer with spheres of a different size than the surrounding colloidal crystal. Dense layers can be introduced by either CVD, electrolyte LbL, PDMS-stamps or maybe another deposition technique. The process consists of growing a photonic crystal, then using electrolyte LbL-deposition or PDMS-stamp make a thin film before making another photonic crystal. It's like a sandwich.

====Manipulating photonic crystals usage====
*Color of the structure is partially determined by the size of its spheres, where small spheres give blue/purple colors and larger spheres goes towards red (from yellow to green and then red).
*Non-close-packed polymerized colloidal crystalline arrays can be made to swell or shrink by external influence. As the diffraction colors of the crystal depend on the spacing between microspheres you can place a hydrogel between the spheres and this gel will swell or shrink depending on external environments. This will make the color change when the gel shrinks or swells as the pH, temperature, water concentration or ionic strength changes.
*The dielectric constant can be changed by changing the material, the structure of the crystal ''or something else that others edit in here''
*An example: Removal of cation causes a hydrogel to shrink, which can be detected at even very small concentrations. The order of cation complexation determines how sensitive the sensor is. Cation selectively binds covalently to the polymer network, sol-gel or hydrogel.

====Core-corona, core-shell-corona and multi-shell microspheres====
Core-corona and core-shell-corona can be made by both re-growth and one stage growth as multishell microspheres probably is better off being made by the re-growth process. The purpose of making these spheres is to put a lot more functionalities into just one sphere. The shells can be fluorescent, magnetic , photoactive, semiconductive, sacrificial or something else pulled out of a hat.

====Growth synthesis====
*One stage: Reagents are mixed and the microspheres are obtained in solution by a nucleation and growth
*Re-growth: First a sees is produced. The seed is then allowed to grow in several steps. Surface tension controls the shape, where low surface tension gives spherical particles.

====Self assembly of photonic crystals====
*Sedimentation (be able to explain in more detail): Use Stokes equation to make the radius as you want it by changing the viscosity very slowly.
*Electrophoresis '''– noen som veit?'''
*Hydrodynamic shear '''– noen som veit?'''
*Spin coating '''– noen som veit?'''
*Langmuir-Blodgett layer-by-layer (be able to explain in more detail) '''– noen som veit?'''
*Parallel plate confinement: Force spheres to assemble by placing them between two parallel plates and slowly moving one plate closer to the other. Important with slow movement to prevent defects. This can be done both dry and in fluid. It is necessary to increase density and viscosity of solvent so that settling occurs slowly in order to control structure and shape, and to avoid defects.
*Evaporation induced self-assembly, EISA (be able to explain in more detail) Capillary forces drive the assembly of spheres in a solution as you remove a wetting plate out of the solution. These the need to be dried and this can cause cracking. Vertical substrate is placed in a dispersion of microspheres. As solvent evaporates, the microspheres are driven by convective forces (forces from movement in solvent towards wall, surface, water meniscus) to the solvent-air meniscus. The layer thickness is determined by the diameter of the microspheres, their volume, concentration and the wetting properties of the solvent on the substrate.

====Colloidal aggregates====
*CA are made either by templated pattern in a surface or by aggregation in a homogeneous emulsion.
Emulsion-way:
*They are disperse microspheres in a solvent such as toulene.
*Add dispersion to solution of surfactant and water
*Stir or shake to get emulsion
*Toulene evapourates and as toulene droplets shrink, microspheres are pulled together in a stable cluster through capillary forces.
Photonic crystal marbles:
*Aqueous dispersion of microspheres is forced, under pressure, through a small syringe in the presence of an electric field. Surface charge on the liquid jet make it break into homogeneously sized spherical particles. Each droplet (sphere) contains a preset quantity of microspheres.
*Electrospraying - '''noen forslag?'''

====Bragg-Snell law====
*The reflected light has a wavelength depending on Bragg's and Snell's law. This then tells us that the wavelength of the first stop band is proportional to distance between the lattice plains. This gives that the longer the distance between the plains (bigger microspheres) gives longer wavelength.
<math>\lambda_{c(hkl)} = 2d_{hkl}\sqrt{\langle \epsilon \rangle - sin^2{\theta}} </math>
der <math>\langle \epsilon \rangle</math> is the effective dielectric constant of the colloidal crystal.

====Cracking====
This happens when the thin hydration layers around the crystal spheres dry out. This creates capillary stress and thermal expansion. To prevent cracking you can dry the crystal slowly, use hydrophobic spheres. Methods for preventing this is:
*<math>SiCl_4</math> reacting within the hydration layer to create a <math>SiO_2</math> layer between the spheres. Rehydrate to form multiple layers. Advantages as good control of layer thickness as it can be controlled/monitores by optical diffraction as a thicker layer res-shifts the diffraction peak.
*Necking at room temperature using vapor phase alternating chemical reactions
*Heat treatment before assembly. This may require pretreatment before assembly to give desired surface charges. Redeisperse and crystallize without volume contraction

====Liquid crystal photonic crystal====
Neither a liquid nor a crystal, but an intermediate state of matter, so called mesophase. Lacks the long range order of the crystalline state and does not exhibit the randomness of the liquid state.
*Themotropics are LCPC which consists of melted anisotropical shapes (rods or discs) where they ar partially alligned. The order of the components in the LCPC is determined and changed bu the temperature.
*Two groups of thermotropics are ''nematic'', where the molecules have no positional order, but they have a long-range orientational order, and ''discotic'', which consists of disc-shaped particles that can orient in a layer-like fashion.
*By applying electric- and/or magnetic fields the small crystals in the liquid will align after the applied fields and this can control the transparency of the film or whatever you have made out of this LCPC. Eksample of usage is privacy/smart windows.
*By using LCPC with an inverse opal you can tune the color by changing the temperature or applying a field of some sort.
*LCPC is thought to be used as tunable photonic crystal device and liquid crystal-colloidal crystal switch.
How can the colors of such a crystal be altered and what can it be used for?

=== Reactions that you need to know: ===
* Reaction of alkane thiolate with gold. Important to know that alkane thiols have a specific affinity for gold (also keep in mind that silver and gold have very similar properties).
* Reaction that occurs when during anodic oxidation of Al to produce porous alumina membranes.
* Reaction that occurs when silica microspheres are formed from Si(OEt)4 and water (section 7.9): <math>Si(OEt)_4 + 2H_2O \rightarrow SiO_2 + 4EtOH</math>

== Eksterne linker ==
*[http://www.ntnu.no/portal/page/portal/ntnuno/AlleEmner?rootItemId=22934&selectedItemId=31007&emnekode=TMT4320 NTNUs fagbeskrivelse]
*[http://www.ntnu.no/studieinformasjon/timeplan/h08/?emnekode=TMT4320-1&valg=emnekode&bokst= Timeplan Høst08]

[[Kategori:Obligatoriske emner]]
[[Kategori:Fag 5. semester]]
[[Kategori:Fag]]

TMT4320 - Nanomaterialer

2008-12-15T07:21:46Z

Audunnys: Mindre endringer/tillegg i kap. 2/3

{{Infobox
|Fakta høst 2008
|*Foreleser: Fride Vullum
*Stud-ass: ?
*Vurderingsform: Skriftlig eksamen
*Eksamensdato: 18. desember
}}

{{Infobox
|Øvingsopplegg høst 2008
|* Antall godkjente: 6/12
* Innleveringssted: Utenfor R7
* Frist: Tirsdager 16:00 (?)
}}

Emnet skal gi en innføring i grunnleggende kjemisk prinsipper for å lage nanomaterialer. Stikkord: "Self-assembled" monolag ([[SAM]]) og hvordan disse kan formes ved myk litografi og "dip pen" nanolitografi, syntese av tredimensjonale multilag strukturer. Tynne filmer ved kjemisk gassfase deponering. Syntese av nanopartikler, nanostaver, nanorør og nanoledninger. Våtkjemiske syntese av oksidbaserte nanomaterialer. "Self-asembly" av kolloidale mikrokuler til fotoniske krystaller, porøse nanomaterialer, blokk-kopolymere som nanomaterialer. "Self assembly" av store byggeblokker til funksjonelle anordninger.

== Oppsummering av pensum ==
Her vil det etterhvert vokse fram et lite kompendium i faget. Dette følger i utgangspunktet pensumlista som gjelder for høsten 2008.
===Chapter 1: Nanochemistry Basics ===
Not terribly important.

===Chapter 2: Soft Lithography===
====Self-assembled monolayers (SAMs)====
*The typical example of a SAM is a layer of alkanethiols on a gold substrate.
*The S-H bond is cleaved on the gold surface and an Au-S covalent bond is formed.
*The alkanethiols are tilted off-axis from the normal. The angle depends on the surface. (30 ° for a {111} gold surface, 10 ° for a silver surface).
*The end group on the alkanethiols can be tailored to achieve different monolayer properties.

====PDMS stamp====
* PDMS = PolyDiMethylSiloxane
* A master (casting) of the stamp, with the desired pattern, is made with lithography. The master is silanized and made hydrophobic so removing the stamp becomes easier.
* Liquid PDMS is then poured into the master, after which it is cured and a finished PDMS stamp is removed from the master.
* The critical dimensions of the pattern are limited by the lithography techniques used, and for [[photolithography]] the wavelengths of the light used to expose the [[photoresist]] limits the dimensions. Typical CDs given are, for lateral dimensions within the range of 500nm-200µm, and for the height of patterns 200nm-20µm.
* The PDMS stamp can be dipped in alkanethiol solutions (or solutions of other molecules, collectively known as "chemical ink") and be stamped onto surfaces
* PDMS stamps work on both planar and curved surfaces
* For the stamp to properly print a pattern onto a surface, the molecules need to adhere to the stamp from the solution, but needs to adhere more strongly to the surface to be printed on.

====Hydrophilic / Hydrophobic stamps====
* The endgroup/terminal group on the alkanethiols (or other molecules used) determine the properties of the monolayer
* By introducing a wetability gradient or abrupt changes in wetability, different effects can be obtained
** Square drops, by having checkerboard square patterns of hydrophobic/hydrophilic monolayers, and condensating a vapor onto the surface
** Drops "running uphill" by having wetability gradients
====Printing thin films====
* As long as the adhesion between the chemical ink and the substrate is stronger than the adhesion between the ink and the stamp, printing thin films is no problem
* Metal thin films can be evaporated onto the stamp (evaporation gives homogenous and directional coatings, not covering the side walls on the stamp) and printed onto a substrate that has been primed with a SAM with exposed thiol groups (adheres strongly to the metal layer)
* This is a very gentle technique for metal film depositing, good for making contacts on fragile layers. Also good for making 3D stuctures by printing multiple layers.
====Electrically conducting SAMS====
* Electronic devices will always need to make electrical contact with SAMs
* Other, less gentle methods of metal deposition than printing with PDMS stamps (sputtering, CVD, etc) can cause the metal layer to penetrate the SAM
* Morale: Use stamps to deposit metals on SAMs!
====Patterning by photocatalysis====
* Photocatalysis is used to remove parts of a SAM (making patterns)
* Titania can photocatalytically decompose organic molecules.
* A quartz slide patterned with titanium dioxide in the required pattern is pressed against a wafer with the SAM on it.
* The assembly is exposed to UV irradiation, triggering the degeneration of the (organic) SAM

===Kapittel 3: Building layer-by-layer===
====Electrostatic superlattices====
* Lbl multilayer films formed by alternate immersion in suspensions of opposite charges
* A primer layer with a charge adheres to the substrate. The substrate is then dipped in a solution of polyelectrolytes of opposite charge from the primer layer. Repeated with opposite charges.
* As the amount and identity of constituents of each layer can be controlled, a composition gradient can easily be constructed throughout the structure.
* Any species bearing multiple ionic charges can be layered.
* Can be applied to curved surfaces like microspheres, enables applications like hollow spheres with a semipermeable cap.

====Some applications====
* Electrochromics layers (change color when a potential is applied), used in "smart windows" for instance
* Construction of cantilevers for AFMs and similar equipment, using photolithography and lbl

====Analysis, measuring film thickness====
* Optical spectroscopy: If the substrate is transparent, and the film absorbs light at a certain wavelength, the film thickness can be found by monitoring the optical absorption as a function of number of layers. A dye can be introduced to ensure absorption. Easy to perform but hard to interpret - must know the observation area and extinction coefficient of the absorbing group.
* Ellipsometry: Film is probed by polarized light, and change in polarization in the reflected light is measured. This can be used to find the refractive index, thickness, roughness and orientation of a thin film. Ellipsometry works with films much thinner than the wavelength of light - down to atomic layers.
* Quartz crystal microbalance (QCM): Quartz (piezoelectric) in an alternating electric field contracts/expands with a characteristic oscillation frequency. When mass is added to QCM the frequency decreases. This allows real-time thickness measurements. Works well for hard materials like metals and ceramics, but not for viscoelastic materials.
* Direct techniques: Label each layer with heavy metal atoms and image by TEM. Alternately, deposit a thin gold layer on top of the surface and image cross section by TEM.

====Non-electrostatic lbl assembly====
* Lbl doesn't need electrostatic bridges - can use hydrogen bonding, ligand-receptor interactions or even covalent bonds.
* Example: DNA (adenine-thymine and guanine-cytosine bridges)
* Hydrogen bonds can be broken again by changing the pH, or can be strengthened by UV irradiation

====Low-pressure layers====
* Molecular beam epitaxy (MBE): Performed in a vacuum, sources of constituents (elemental) are heated, and a thin film alloyed from the constituents is deposited. The result is a homogeneous crystal. The substrate should have a similar lattice constant to that of the layer deposited.
* Chemical vapor deposition (CVD): Volatile precursors are introduced in gas phase in a low-pressure reactor chamber. Argon gas is used to dilute the precursor gas to achieve optimal pressure and concentration. The substrate is heated, and the precursor decomposes at the surface.

====Lbl self-limiting reactions====
* Atomic layer deposition: Similar to CVD, but usually carried out in solution.
* Iterative saturating reactions.

=== Kapittel 4: Nanocontact printing and writing ===

''Dag H. jobber med kap.4''
* Soft lithography and microcontact printing
-Sub 100 nm Soft Lithography: Previous chapters has covered printing on 10.000-100 nm scale. Need for further miniaturization because of demand for more power, efficiency, and density. This can be done by manipulating PDMS stamp, Dip Pen Nanolithography (DPN),Whittling Nanostructures or by Nanoplotters

**Manipulating PDMS stamp: Manipulating PDMS stamp can be done in various ways, and seven of the basic ideas will now be explained. Illustrating pictures are in the book and in foils. 1) Compress the stamp, mold to get a new stamp with inverse pattern, peel off and repeat. 2) Apply force perpendicular onto stamp when on substrate. The areas in contact with substrate will then increase, and spaces in between gets smaller. 3) Size reduction by reactive spreading some sort of ink when in contact with substrate. The contact time + properties of the ink decide to which degree the ink spreads. 4) Size reduction by extraction of inert filler (just like retracting water from a sponge). 5) Size reduction by swelling the stamp in toluene. 6) Size reduction by stretching stamp so that dimensions get smaller in one axis and larger in another. 7) Size reduction by double-printing. Limitations:Deformation can be a shortcoming if care is not taken with the dimensions of surface relief pattern in the stamp as this can give unwanted deformations. Quality of printed pattern will not be good. Defect-free contact printing is restricted to a certain range of height-to-width ratios. If ratio is outside 0,2-2, the roof of the grooves on stamp will touch the substrate.Too high perpendicular force on stamp has the same effect, but overpressure can also be used to form new patterns such as micron scale discs and rings of ferromagnetic core-shell nanoparticles. Nanoparticles are then transferred to PDMS stamp by Langmuir-Blodgett technique (chapter 6) and then into contact with Au-coated silicon substrate. Low pressurediscs, high pressurerings.

** Dip pen nanolithography: Alkanethiols can be written on gold substrate with AFM tip. The alkanethiols are delivered to the tip via a water meniscus, and this can be adapted to suit other surface chemistries. The result is 10 nm fine patterns of molecules (biomolecules, polymers etc.) on metals, semiconductors and dielectrica.
*** Sol-gel DPN:patterning of solid-state materials. Nanoscale patterns are written using a metal oxide sol-gel precursor in a solvent carrier. The sol-gel precursors are hydrolyzed to metal oxide by use of atmospheric moisture and water meniscus at the tip-substrate interface. pH, substrate temperature and post treatment can be varied.
***Enzyme DPN: A scanning microscope tip can be used to place an enzyme on a specific site on a biomolecule with nanometer presicion. This method leads to the possibility of bionanodegradable electronic and optical devices.
***Electrostatic DPN: Like thin films can be made of charged polyelectrolytes, an AFM tip can "draw" lines or structures of charged polymers with for example specific electrical properties to build nanoscale electronic devices.
***Electrochemical DPN: The meniscus that forms between surface and tip is used as a nanochemical reactor. Electrochemical deposition can be done by applying voltage between tip and substrate. Ex: making platinum lines can be made by reducing Pt salt at -4 V, and silica lines can be made by oxidation of silicon surface at +10 V.

** Whittling of nanostructures (section 4.19)
** Only be able to explain basic principle
***The spatial extent of SAMs can be reduced by so-called "whittling". Whittling is an electrochemical desorption process where a voltage applied will cause ligands to desorbate. It has been found that the larger the accessibility of a molecule, the lower the desorbation voltage is (fig. 4.22)
* Nanoplotters and nanoblotters
** What are these and what can they be used for?
***Nanoplotter: Parallel cantilevers write SAM nanopatterns simultaneously.
***Nanoblotters: An PDMS inkwell has been created to deliver ink to the nanoplotter cantilever tips (fig. 4.26)
** Be able to explain basic principles.
* Combinatorial libraries
** Be able to explain the basic principle and how it is used to find new and improved materials.
***Combinatorial libraries: DPN can be used to put different materials together in the research of new material composition. With DPN, many different combinations can be made with small material amounts used.

=== Kapittel 5: Nano-rod, nanotube, nanowire self-assembly ===

''Emily skriver på denne. Håper folk retter opp dersom de finner feil, og legg gjerne til flere ting:)''

====Templating nanowires and nanorods====
Templates can be used for making solid nanowires/nanorods/nanotubes of controlled sizes. Examples of templates are alumina, silicon, zeolites and lipid bilayers.

====Making modulated diameter silicon templates====
A p+ doped silicon wafer is put in aqueous HF and an oxidizing potential is applied. The result from this is nanoporous silicon with random network pores. The diameter of the pores can be tuned by controlling the voltage or current. The higher the current is, the wider the channels get. If perfectly ordered pores are desired, the wafer can be lithographically patterned with regular array of nanowells in advance. The electric field will then be focused at the tip of these wells.

====Making porous alumina membranes====
Porous alumina membranes can be made by anodic oxidation of lithograpically embossed aluminum sheet in phosphoric or oxalic acid electrolyte (the almunium sheet functions as the anode).

<math> 2Al + 3PO_4^{3-} \rightarrow Al_2O_3 + 3PO_3^{3-}</math>

The residual Al and Al2O3 is removed by mercuric chloride and phosphoric acid. The diameter is controlled and can be 20-500nm. Mechanisms that give ordered channels are the fact that electric fields created by applied voltage repell each other, and that we have volume expansion when aluminum becomes alumina. Temperature is also a factor that affects the reaction.

====Modulated diameter gold nanorods====
With use of silicon template. The back surface of the silicon membrane is subjected to a local thermal oxidation which formes silica. The silica is then removed by HF. By proceeding with a KOH anisotropic etch on the same area, and a dip in HF, the pores in the template are opened. A gold sputter deposition can then be done on the backside. This gold layer acts as a catalyst for continued electroless deposition of gold. Finally, the silicon membrane is etched away, and the gold nanorod dispersion can be collected.

====Modulated composition nanorods/nanobarcodes====
Modulated composition nanorods can be made by electrochemical deposition of different metal segments within the channels of an alumina template (electrodeposition will be better explained in the following section). Any type of material that can be electrodeposited can be used in the nanobarcodes. One synthesis route is to evaporate thin metal film to one side of an alumina membrane. This metal film function as the cathode, and metal deposition begins at the bottom. Bath can be switched between different metal salts to grow several segments. The alumina membrane is dissolved using sodium hydroxide, and the metal backing is dissolved using acid.

Nanobarcodes can be used to tag molecules in analytical chemistry and biology. Characteristic of metals are optical reflectivity, which means that different segments of the barcode nanorod can be distinguished in optical microscopy. Probe molecules must be anchored to different segments, and the rods must be dispersed in analyte containing target molecules which bear a luminescent label. By molecular recognition, the target molecules bind to the probe molecules (ex: ligand-receptor binding for biological applications). By looking at the segments that light up, it can be decided which molecules excist in the solution.

====Electroplating/electrodeposition====
The part to be plated is the cathode, while the anode is made of the material to be plated. Both components are immersed in electrolyte solution. The dissolved metal ions (cations) are reduced at the interface between the solution and the cathode when current is applied.

====Electroless deposition====
Spontaneous reduction of a metal (ex: copper or silver) from a solution of its salt. A reducing agent (which acts as the source of the electrons) is required, but no current is required. The surface acts as a catalyst to allow the deposition to proceed (ex: the gold sputtered layer in making the gold nanorods in alumina).

====Nanotubes====
Nanotubes can be made by partial filling of the membranes radially. This means that a uniform coating must be deposited on the pore walls. One way to do this is by letting fluid spontaneously wet inside the template pores. Fluids that can be used are molten polymers, polymer solution or sol-gel preparation. These are coated onto template using capillary forces resulting from small diameter channels with a large available surface. Solidification of these fluids can be done by heating, cooling, waiting or using a catalyst. With this method it is difficult to control the wall thickness.
Another way to make nanotubes is by using LbL growth procedure inside the pores. This can be done by CVD of gas phase species, solution phase ALD or LbL electrostatic assembly. Wall thickness is easier to control with these methods.
Finally, the membrane is dissolved. It can also be deposited other material inside the remaining void to get coaxially coated rod or wire.

Nanotubes can also be made from LbL electrostatic coating of nanorods. The rods can be dissolved afterwards, and will leave a closed-ended tube. This method is applicable to any material that can be coated onto a nanorod and not be affected by the etching step.

====Magnetic Nanorods====
Magnetic metals such as iron, cobalt or nickel can easily be deposited into membranes. Magnetic properties are direction and size dependent. If the thickness of the magnetic segments on a nanorod is smaller than the diameter, they will self assemble into 3D bundles. If the thickness is bigger than the diameter, they will align in chains of rods. If the thickness is the same as the diameter they will be in random aggregates. Magnetic nanorods can be used for separation of molecules. A tri-segmented Au-Ni-Au nanorods can be used as affinity template for histidine- tagged proteins. Nickel selectively captures the labeled protein, and a magnetic field can be used to separate the rod with the captured protein from the rest of the solution of biomolecules. After this, the proteins can be chemically released from the magnetic nanorod. The gold segments must be in the rod to protect nickel from the etching during dissolution of alumina template after electrodeposition, and also to prevent aggregation.

====Making Single Crystal Nanowires====
Single crystal nanowires can be made by Vapor-Liquid-Solid (VLS) synthesis, Supercritical Fluid-Liquid-Solid (SFLS) synthesis or by Pulsed laser deposition.

*VLS Synthesis
A catalyst droplet first melts, then becomes saturated with precursors. Elements extrude out of the catalyst droplet as a single crystal nanowire in a furnace where the temperature is controlled to maintain liquid state of the catalyst droplet. Micrometer length with diameter less than 10 nm can be done. The diameter is controlled by the diameter of the catalyst droplet, and growth stops when the nanowire pass out of the hot zone, if the precursor is depleted or the catalyst droplet no longer is in liquid state. One example is to use laser ablation of Fe-Si target to create a Fe-Si nanocluster catalyst droplet. The Si nanowire grow with the (111) lattice planes perpendicular to the growth axis due to epitaxy at the nanocluster-nanowire interface. Doping can be done by controlling stoichometry of the target, or by introducing dopant into gas phase during growth.

*SFLS Synthesis
Similar to VLS, but used for high-eutectic temperature combinations. The solvent is pressurized above its critical point to reach higher temperatures. Can be applied to semiconductor/metal combinations (Ga/GaAs, In/InN) with eutectic temperature below 600 degrees. Au is used as catalytic seed, and diameter depends on this.

*Pulsed laser deposition
?????? laser ablation?????

====Nanowires branch out====
Can create branched nanowires by VLS growth. The catalytic nanoclusters from solution placed on specific point on the body of a parent nanowire before growth. The process can be repeated for a hyper-branched construction. This could be the future development of nanowire electronics in 3D.

====Quantum Size Effects (QSE)====
QSE appear when the particle size becomes smaller than the exciton size for the material (about 5 nm for silicon). Exciton is a bound state of an electron and an electron hole in an insulator or semiconductor, which is defined by the energy gap between the valence band and the conduction band. Color of the emitted light is determined by the size of gap energy. Gap energy increases with decreasing nanowire diameter. This can be used for LEDs and lasers. Both quantum confined nanoclusters and nanowires show QSE, but anisotropy make them different. Luminescent nanocluster emits plane-polarized light, while nanorod exhibits linearly polarized light.

====Alignment methods====
Alignment methods include electric field based alignment, microfluidic alignment and Langmuir-Blodgett technique.

*Electric Field Based Alignment
Apply voltage between two micropatterned electrodes to produce electric field. Charges within a nanowire in solution become polarized, creating an attraction between the electrodes and the nanowire. The electric field is quenched when the gap between the electrodes are bridged by a nanowire. This eliminates absorption of a second nanowire at the same electrodes. Metal spots can be evaporated onto insulator surface to focus the electric field.

*Microfluidic Alignment
A PDMS stamp with a series of parallel rectangular grooves is used for this purpose. The channels are aligned under a microscope with electrodes that have been previously patterned on a substrate (these will function as metal contacts for the conducting or semiconducting lines made by this method). A drop of nanowire suspension is flowed into the microchannels by capillary forces, and solvent evaporation aligns the wires at the edges of the channels.

*Langmuir-Blodgett Technique
A Langmuir film is first created when a small amount of insoluble liquid (amphiphile) is poured onto another liquid. The balance of surface tension forces determines the profile of the meniscus formed when a substrate is pushed into this liquid. If the substrate is hydrophobic it will experience deposition of the amphiphiles during immersion. If it is hydrophilic it will experience deposition during retraction. A nanowire array can be made by firstly compressing the interface to increase the surface density of nanowires (so they align parallel to each other), and then do a double dip. The second dip must be done so that the wires align normal to the previous once.

Application areas for these methods are in LED’s, transistors and in nanowire UV photodetectors.

====LED====
A LED is a two terminal device consisting of an n-doped and a p-doped semiconductor (eg. nanowires). To collect the doped nanowires into LED structure, voltage is firstly applied to one pair of electrodes, and then the second pair so that they lie in a cross. They can also be assembled by using the microfluidic approach. Light is emitted when electrons recombine with holes at the junction between the differently doped wires. Color of the emitted light depends on composition and condition of semiconducting material used. The LED can only conduct current in one direction. With positive voltage current flows. With negative voltage current is inhibited. The key for success is to achieve abrupt and uncontaminated junction between n and p doped wire. Efficiency can be improved by using core-shell-shell nanowire axial heterostructure. The greatest challenge is to make arrays of closely spaced junctions because the nanowires are so thin. This leads to the pitch problem, how to pack light sources into smallest possible area.

====Transistors====
A transistor can switch or amplify signals, and has three terminals (n-p-n). The n-type region attached to the negative end of the battery sends electrons into p-region, and the n-type region attached to the positive end slows the electrons down. The p-type region in the middle does both. Because of this, a depletion layer develops between the base and the emitter, and the base and the collector. The thickness of the layer is varied by the potential in each region. Active bipolar n-p-n transistor can be built from heavy and lightly n-doped nanowires crossing a common p-type wire base.

====How can nanowire transistors be used as sensors?====
Si nanowires are naturally coated with silica through VLS synthesis. This makes it easy for surface silanol groups to attach to the wire. If probe molecules are anchored to the surface silanols, highly sensitive real time electrically based sensors can be made. Low levels of chemical and biological species can be detected. Boron doped silicon nanowire is used as a FET. The wire is self assembled across electrodes (source and drain), and aminoethylsilane anchored to SiOH surface groups. The conductance of the wire changes with pH linearly due to protonation or deprotonation of the amine. An increase of the surface negative charge (deprotonation) attracts additional holes into the p-channel and the conductance is enhanced. The reverse action at low pH, an increase of surface positive charge causes protonation which repell holes from the channel. The conductance is decreased. Almost any type of molecule can be anchored to silica, so sensors can be designed to detect almost anything. For example, a biotin could be strapped to the surface amine groups to detect streptavidin.

====Nanowire UV photodetector====
The conductivity of ZnO nanowires is extremely sensitive to ultraviolet light exposure, which means that UV light can switch the nanowires between ON and OFF states. ZnO nanowires are highly insulating in the dark, but UV light with wavelength less than 380 nm decreases resistivity by 4 to 6 orders of magnitude. These nanowire photoconductors exhibit excellent wavelength selectivity. Green light (532nm) gives no response, while less intense UV light increases conductivity 4 orders. The response cut-off wavelength is at about 370 nm.

====Simplifying complex nanowires====
Complex oxides with superconducting, ferroelectric and ferromagnetic properties can not easily be made as nanowires by conventional methods. MgO nanowires must be used as templates. Firstly, single crystal orthogonal MgO nanowires are grown on single crystal MgO substrate. Oxygen is flowed over Mg3N2 at 900 degrees as precursor for VLS, using Au catalyst. After the MgO nanowires have been made, the complex metal oxide is deposited by pulsed laser deposition to create a shell on the surface of MgO wires. Another approach to simplify complex nanowires is to use hydrothermal synthesis. This can be used to make PbTiO3 nanorods which is a ferroelectric material and potentially useful as building blocks in nanoelectrochemical systems. (Amorphous PbTiO(3-X)(OH)2X precursor is mixed with sodium dodecyl benzene sulfonate surfactant and reacted at 48 h at 180 degrees at alkaline conditions in the presence of a substrate.) The nanorods obtained have a squared cross section 35-400 nm, and up to 5 um long. The rods grow in the (001) direction by self-assembly of nanocubes to anisotropic mesocrystals, which is ripened into nanorods.

====Electrospinning====
Electrospinning is nanofiber extrusion in a capillary jet. A polymer solution or polymer sol-gel pass through a high voltage metal capillary to create a thin charged stream. The stream undergoes stretching, bending and solvent evaporation. The charged nanofibers are driven to ground electrodes. The dimensions of the fibers depend on solvent viscosity, conductivity, surface tension and precursor concentration. The collector electrodes can be patterned to make organized arrays between them by electrostatic self assembly. The electrodes can be grounded simultaneously or sequentially. This can be used to make single layer or multilayer nanowire architectures.

====Hollow nanofibers by electrospinning====
Hollow nanofibers can be made by co-axial double capillary electrospinning that creates heavy mineral oil core with inorganic polymer around (Ti and PVP). The core-shell nanofibers are collected on an aluminum or silicon substrate and hydrolyzed. The oily core can be extracted with octane, which creates nanotubes with amorphous TiO2 + PVP. To crystallize TiO2 and oxidate PVP, the tubes can be calcined in air at 500 degrees.

====Dual electrospinning====
A side by side spinneret can be used to make bicomponent fibers. Ex: two solutions containing TiO2/SnO2 are simultaneously jetted. This is calcined. A heterojunction of SnO2/TiO2 can create devices with extremely high quantum efficiency and photocatalytic activity for treatment of organic pollutants in water and air.

Dette mangler:
* Carbon nanotubes (sections 5.41, 5.42, 5.44, 5.45-5.48 and lecture notes)
** What are carbon nanotubes? Be able to describe the three different structures they can have and how their properties are different.
** Be able to describe briefly (basic principles) at least two of the three main methods used to synthesize carbon nanotubes
*** Arc discharge
*** Laser ablation
*** CVD
** How can the different structure nanotubes be separated from each other and from other carbon particles.
** Be able to say something about their properties
*** Mechanical
*** Electrical
*** Chemical
** Know some about carbon nanotube chemistry (reactivity on the surface vs the ends etc.)
** Aligning of carbon nanotubes
*** Evaporation induced self-assembly
*** Patterned hydrophilic SAM on substrate – carbon nanotubes will assemble only on the hydrophilic patches.
*** Alignment by pre-existing patterns
**** Perpendicular to substrate
**** Parallel to substrate
*** AC/DC electric fields
** Applications of carbon nanotubes
*** Sensors
*** Strengthening of materials (composites)
*** Added to materials to improve conductivity

=== Kapittel 6: Nanocluster Self-Assembly ===

====Capped nanoclusters====

A capped nanocluster is a nanometer scale particle with well-defined positions of the constituent atoms. They nucleate from atoms and enter a size range where they behave electronically as molecular nanoclusters. As the number of atoms increases further, they cross over into the nanoscale size domain where quantum size effects dominate, they become quantum dots. A capped nanocluster has a monolayer of a capping ligand on the surface, which can be a polymer or an alkane thiol (if the surface is silver or gold) or some other molecule with an end group that will bind to the surface of the nanocluster. The capping molecules will prevent further growth of the nanocluster. Capping groups serve multiple purposes:
*Change solubility properties
*Enable size-selective crystallization
*Surface functionalization
*Protect nanoclusters from luminescence or charge-carrier quenching

====General principles for synthesis of capped nanoclusters (arrested nucleation and growth)====

One general synthesis method is the arrested nucleation and growth synthesis. The basic idea is to rapidly create a large number of nucleated seeds (of desired materials) and then allow these to grow at the same rate below supersaturation conditions. This method can be described by the following steps:
* Desired precursors are added to a solution containing a proper capping agent, which is held at an intermediate temperature (200-400 °C depending on the materials. Temperature needs to be high enough to overcome the activation energy for the reaction.).
* Precursors need to be added at an amount that is over the saturation point for the materials in that specific solution.
* Materials will rapidly nucleate (precipitate) and start growing. Once the first molecules have reacted and created a small seed, the energy required for further growth is smaller than the initial activation energy. The nucleated seed can therefore continue to grow below the saturation concentration for the precursor materials.
* Once the nanoclusters reach a certain size range, which may vary from one material to the other, the capping agents will adsorb on the surface of the nanoclusters and prevent further growth. The nanoclusters that are formed will not all have the same diameter, but a range of different diameter clusters will be formed. This can be due to for example concentration gradients in the reactor or reaction medium.

====Minimize size dispersity by confining the reaction space====

The size of the capped nanoclusters can be controlled by growing them in nanowells made by the methode in figure x. The nanowells are obtained by patterning a silicon wafer with a layer of well-ordered microspheres. By pressing the microspheres against a the wafer and at the same time melt the surface of the wafer with a pulsed laser molten silicon will flow into the voids between the spheres. The size of the nanowells depend on the size of the spheres, the energy density of the laser pulse and applied mechanical pressure, while the size of the crystals depend on the well volume and concentration of the reactants. The crystals can be removed by ultrasound. The downside of the approach is that the amount of nanocrystals obtained will be quiet small.

====Tuning properties through physical dimensions rather than chemical composition (QSE)====

When electrons are confined in space the size invariant continuum of electronic states of bulk matter transformes into size dependent discrete electronic states in a quantum dot. At the 1-5 nm length scale, which is the CdSe nanocluster size range, the parent continuous electron bands of the bulk semiconductor becomes discrete. The nanoclusters then belong to the quantum size regime, and the properties begin to scale in a predictable fashion with size. By looking at the Schrödinger wave equation it can be seen that there is a blue quantum size effect shift in the energy of the first exciton band or band gap that scales with the reciprocal of the square of the radius of the nanocluster. The wavelengths absorbed change, and the colors of the nanoclusters can be alterd from yellow to red, by changing the physical size of the clusters

====How can different phases occur for smaller size particles?====

Similar to temperature and pressure, phase transformations in bulk materials are dependent on size. Phase transitions that are prohibited or slowed down by activation energies in the bulk can occur much more readily in nanocrystals of same material. Because of the small size of the crystal the influence of bulk and surface-free energies are different from in a bulk matter. Phase transformations show a distinct dependence on nanocrystal size. It can be shown that phase of nanoclusters can change just by exposing them to a different chemical environment at room temperature.

====Makeing nanoclusters water soluble====

Why? Water is cheap, widely available and use of it avoides the disposal o organic solvents, which can be quiet harmful for the environment. (Green chemistry). You can use the same principles as for the SAM surface chemistry. A hydrophilic SAM is made by choosing a hydrophilic group such as a carboxylate, ammonium or oligo ethylene glycol. In the case of a gold nanocluster, a thiol with a terminal carboxyl group gives an ionized, water loving carboxylate when in aqueous solution. Hydrophobic nanoclusters can be wrapped by amphiphilic polyers. The polymer coating is stabilized by partially cross linking the anhydride gropuos with bis(6-aminohexyl)amine. Can also coat with silica. Often, the resulting crystals bear a surface charge, which allows their use in electrostatic layer-by-layer deposition.

====Separation of nanoclusters by size using using a non-solvent and centrifugation====

Nanoclusters can be dissolved in toluene and by gradually adding a non-solvent (e.g. acetone) the nanoclusters will precipitate. The largest clusters precipitate first. Every time a bit of acetone is added the solution is centrifuged and the precipitate collected. The result is highly monodisperse nanoclusters collected in each fraction.

====Superlattice====

A superlattice is a material with periodically alternating layers of several substances. Such structures possess periodicity both on the scale of each layer's crystal lattice and on the scale of the alternating layers.

====Assembling of superlattices====

A superlattice can be assembled by means of these techniques:
*Tri-layer solvent diffusion crystallization - Three immiscible solvents are arranged to form separate layers in a test tube. Bottom layer →capped CdSe nanoclusters dissolved in toluene. Middle layer →buffer layer of 2-propanol selected for poor solvent properties wrt the nanoclusters. Top layer →non-solvent for the nanoclusters such as methanol. The process involves slow diffusion of the nanoclusters from the toluene bottom layer and the methanol from the top layer into the buffer layer. The change in solvent properties causes a slow and controlled nucleation and growth of capped CdSe nanocluster crystals.
*Sedimentation –
*Evaporation induced self-assembly – Strong capillary forces in an evaporating water meniscus drives the nanocomponents into close-packing.
*Langmuir-Blodgett – A dilute monolayer of capped silver nanoclusters is spread on an air-water interface. Using Langmuir – Blodgett “equipment”, this monolayer can gradually be compressed until a compact monolayer is formed.

====Gjenstår====

*Why do we want to make superlattices? (change of properties, properties of superlattice does not necessarily equal the sum of the properties of the individual constituents)How can capping agents (different type and length) affect the properties of a superstructure? (section 6.15)Alloying core-shell nanoclusters

* Nanocluster-polymer composites
** What is it?
** How can it be used for down-conversion of light?
* Be able to give one or two examples of how different size nanoclusters labeled with different fluorescent molecules can be used in biology.
* What is a tetrapod and what is the main priciples of the synthesis behind the tetrapod?
** Using a material that has two common crystal polymorphs where growth of one over the other can be controlled by synthesis temperature.
** Use of a long chain molecule which selectively binds to specific facets of the structure and hinders growth in those directions. This confines the growth of the material to one spatial dimension.
* Photochromic metal nanoclusters (section 6.31)
** Be able to explain what happens to silver nanoclusters embedded in a titania matrix when it is exposed to either UV-light or visible light.
* What is a buckyball and what can it be used for? What special properties does it exhibit? (Do not need to know specific details of synthesis or assembly techniques.)

=== Kapittel 7: Microspheres – Colors from the Beaker ===

Nå ferdig med så mye som forfatteren greide, men finn gjerne ut resten og del det med alle!

====What is a photonic crystal? ====
*It is a crystal consisting of a material with high dielectric contrast and periodicity at the light scale
*Vullums definition: Natural gratings that diffract light are based on dielectric lattices with periodicity at optical wavelengths. 3D optical diffraction gratings have dielectric lattices that are geometrically complimentary.
*1D PC (planes) is a crystal which only inhibit light to travel in one direction
*2D PC (rods) inhibits light to travel in two directions
*3D PC (spheres) inhibits litght to travel in any direction and has a full photonic band gap (PBG), whilst 1D and 2D only have so called stopgaps

====Photonic Crystal defects====
*Point defects: Holes, missing spheres, in a 3D PC can trap light inside the crystal
*Line defects: Many holes which make a line can guide light through a crystal
*Plane defects: A missing plane or a defect in a plane can make photons slip through to the other side. Planes consisting of another type of material can cause the perfect reflection curve of a PBG-crystal to drop at certain wavelengths depending on the size of the defect.

====Making defects====
*Writing defects: Multiphoton laser writing using a confocal optical microscope induced polymerization of an organic monomer in the colloidal crystal to create small line inside the photonic lattice. Then you treat the crystal and remove the polymer. In reversed opal structures you can use laser microwriting where you attach a laser to a scanning optical microscope which again changes the phase (which again changes the refractive index) of the inverse opal by annealing.
*Synthesizing planar defects: Introducing a dense layer or a layer with spheres of a different size than the surrounding colloidal crystal. Dense layers can be introduced by either CVD, electrolyte LbL, PDMS-stamps or maybe another deposition technique. The process consists of growing a photonic crystal, then using electrolyte LbL-deposition or PDMS-stamp make a thin film before making another photonic crystal. It's like a sandwich.

====Manipulating photonic crystals usage====
*Color of the structure is partially determined by the size of its spheres, where small spheres give blue/purple colors and larger spheres goes towards red (from yellow to green and then red).
*Non-close-packed polymerized colloidal crystalline arrays can be made to swell or shrink by external influence. As the diffraction colors of the crystal depend on the spacing between microspheres you can place a hydrogel between the spheres and this gel will swell or shrink depending on external environments. This will make the color change when the gel shrinks or swells as the pH, temperature, water concentration or ionic strength changes.
*The dielectric constant can be changed by changing the material, the structure of the crystal ''or something else that others edit in here''
*An example: Removal of cation causes a hydrogel to shrink, which can be detected at even very small concentrations. The order of cation complexation determines how sensitive the sensor is. Cation selectively binds covalently to the polymer network, sol-gel or hydrogel.

====Core-corona, core-shell-corona and multi-shell microspheres====
Core-corona and core-shell-corona can be made by both re-growth and one stage growth as multishell microspheres probably is better off being made by the re-growth process. The purpose of making these spheres is to put a lot more functionalities into just one sphere. The shells can be fluorescent, magnetic , photoactive, semiconductive, sacrificial or something else pulled out of a hat.

====Growth synthesis====
*One stage: Reagents are mixed and the microspheres are obtained in solution by a nucleation and growth
*Re-growth: First a sees is produced. The seed is then allowed to grow in several steps. Surface tension controls the shape, where low surface tension gives spherical particles.

====Self assembly of photonic crystals====
*Sedimentation (be able to explain in more detail): Use Stokes equation to make the radius as you want it by changing the viscosity very slowly.
*Electrophoresis '''– noen som veit?'''
*Hydrodynamic shear '''– noen som veit?'''
*Spin coating '''– noen som veit?'''
*Langmuir-Blodgett layer-by-layer (be able to explain in more detail) '''– noen som veit?'''
*Parallel plate confinement: Force spheres to assemble by placing them between two parallel plates and slowly moving one plate closer to the other. Important with slow movement to prevent defects. This can be done both dry and in fluid. It is necessary to increase density and viscosity of solvent so that settling occurs slowly in order to control structure and shape, and to avoid defects.
*Evaporation induced self-assembly, EISA (be able to explain in more detail) Capillary forces drive the assembly of spheres in a solution as you remove a wetting plate out of the solution. These the need to be dried and this can cause cracking. Vertical substrate is placed in a dispersion of microspheres. As solvent evaporates, the microspheres are driven by convective forces (forces from movement in solvent towards wall, surface, water meniscus) to the solvent-air meniscus. The layer thickness is determined by the diameter of the microspheres, their volume, concentration and the wetting properties of the solvent on the substrate.

====Colloidal aggregates====
*CA are made either by templated pattern in a surface or by aggregation in a homogeneous emulsion.
Emulsion-way:
*They are disperse microspheres in a solvent such as toulene.
*Add dispersion to solution of surfactant and water
*Stir or shake to get emulsion
*Toulene evapourates and as toulene droplets shrink, microspheres are pulled together in a stable cluster through capillary forces.
Photonic crystal marbles:
*Aqueous dispersion of microspheres is forced, under pressure, through a small syringe in the presence of an electric field. Surface charge on the liquid jet make it break into homogeneously sized spherical particles. Each droplet (sphere) contains a preset quantity of microspheres.
*Electrospraying - '''noen forslag?'''

====Bragg-Snell law====
*The reflected light has a wavelength depending on Bragg's and Snell's law. This then tells us that the wavelength of the first stop band is proportional to distance between the lattice plains. This gives that the longer the distance between the plains (bigger microspheres) gives longer wavelength.
<math>\lambda_{c(hkl)} = 2d_{hkl}\sqrt{\langle \epsilon \rangle - sin^2{\theta}} </math>
der <math>\langle \epsilon \rangle</math> is the effective dielectric constant of the colloidal crystal.

====Cracking====
This happens when the thin hydration layers around the crystal spheres dry out. This creates capillary stress and thermal expansion. To prevent cracking you can dry the crystal slowly, use hydrophobic spheres. Methods for preventing this is:
*<math>SiCl_4</math> reacting within the hydration layer to create a <math>SiO_2</math> layer between the spheres. Rehydrate to form multiple layers. Advantages as good control of layer thickness as it can be controlled/monitores by optical diffraction as a thicker layer res-shifts the diffraction peak.
*Necking at room temperature using vapor phase alternating chemical reactions
*Heat treatment before assembly. This may require pretreatment before assembly to give desired surface charges. Redeisperse and crystallize without volume contraction

====Liquid crystal photonic crystal====
Neither a liquid nor a crystal, but an intermediate state of matter, so called mesophase. Lacks the long range order of the crystalline state and does not exhibit the randomness of the liquid state.
*Themotropics are LCPC which consists of melted anisotropical shapes (rods or discs) where they ar partially alligned. The order of the components in the LCPC is determined and changed bu the temperature.
*Two groups of thermotropics are ''nematic'', where the molecules have no positional order, but they have a long-range orientational order, and ''discotic'', which consists of disc-shaped particles that can orient in a layer-like fashion.
*By applying electric- and/or magnetic fields the small crystals in the liquid will align after the applied fields and this can control the transparency of the film or whatever you have made out of this LCPC. Eksample of usage is privacy/smart windows.
*By using LCPC with an inverse opal you can tune the color by changing the temperature or applying a field of some sort.
*LCPC is thought to be used as tunable photonic crystal device and liquid crystal-colloidal crystal switch.
How can the colors of such a crystal be altered and what can it be used for?

=== Reactions that you need to know: ===
* Reaction of alkane thiolate with gold. Important to know that alkane thiols have a specific affinity for gold (also keep in mind that silver and gold have very similar properties).
* Reaction that occurs when during anodic oxidation of Al to produce porous alumina membranes.
* Reaction that occurs when silica microspheres are formed from Si(OEt)4 and water (section 7.9): <math>Si(OEt)_4 + 2H_2O \rightarrow SiO_2 + 4EtOH</math>

== Eksterne linker ==
*[http://www.ntnu.no/portal/page/portal/ntnuno/AlleEmner?rootItemId=22934&selectedItemId=31007&emnekode=TMT4320 NTNUs fagbeskrivelse]
*[http://www.ntnu.no/studieinformasjon/timeplan/h08/?emnekode=TMT4320-1&valg=emnekode&bokst= Timeplan Høst08]

[[Kategori:Obligatoriske emner]]
[[Kategori:Fag 5. semester]]
[[Kategori:Fag]]

Hjelp:Hjelp

2008-12-13T23:18:40Z

Audunnys:

== Kort om Nanowiki ==
Nanowiki er en wiki som det er meningen at alle som går MTNANO samt andre interesserte skal bidra til å utvikle.

Litt av poenget med en wiki som dette er at alt man skriver i utgangspunktet kun er et ''utkast'', noe som betyr at man ikke trenger å ha et perfekt produkt klart når man trykker på "Lagre siden". Dersom noe er feil, mangelfult eller dårlig formulert kan man endre det senere, eller noen andre kan gjøre det. En wiki er en levende kunnskapsdatabase.

== Om å opprette artikler ==
For å opprette en ny artikkel: Søk på det navnet du vil ha på siden i søkeboksen og trykk på "opprett artikkel". Alternativt, kan man klikke på en rød link i en eksisterende artikkel. Dette vil ta en direkte til en boks hvor man kan begynne å skrive den nye artikkelen.

{{Hjelp:Hvordan_redigere}}

== Diskusjoner ==
Alle meninger om innholdet i en artikkel diskuteres i den aktuelle artikkelens diskusjonsside. Når du legger inn et nytt innlegg i en diskusjon er det greit å lage innrykk slik at du alltid har et nivå innrykk mer enn det innlegget du svarer på. For å lage innrykk bruker du en kolon på starten av linja. Det vil si at hvis du skal svare på noe som er et svar på innlegget som startet diskusjonen (vi er altså på nivå tre), begynner du linja med to kolon, for eksempel blir
<nowiki>:: Jeg er helt uenig. --~~~~</nowiki>
til
:: Jeg er helt uenig. --[[Bruker:Audunnys|Audunnys]] 13. des 2008 kl. 23:18 (UTC)

Diskusjon:Retningslinjer for nanowiki

2008-12-13T23:08:28Z

Audunnys:

Disse er ikke nødvendigvis de absolutte reglene for nanowiki, men tenkte å sette i gang en debatt om bruk av denne wikien. Synspunkter? --[[Bruker:Goranb|Goranb]] 22. okt 2008 kl. 21:52 (UTC)

Føler at vi burde kjøre en konsis linje i alle fall. Det burde være en eller annen form for struktur (les: sensur). Hva er egentlig vitsen med å ha artikler her som ikke er spesiellt rettet mot linja og som kan finnes andre steder (les: wikipedia)? --[[Bruker:Mariusuv|Mariusuv]] 23. okt 2008 kl. 19:34 (UTC)

Når kommer egentlig denne avgjørelsen av at disse 'regler' skal bli innført i og med at de foreløpig kun er ansett som et forslag? --[[Bruker:Mariusuv|Mariusuv]] 24. okt 2008 kl. 17:06 (UTC)

Det er vel OK å skrive enkle artikler om ting som SEM, TEM ol. selv om dette står på wikipedia? Er jo greit å ha litt mer kortfattetede og forståelige artikler? (Spør selvfølgelig om tilgivelse, ikke tillatelse) --[[Bruker:Mariusuv|Mariusuv]] 26. okt 2008 kl. 16:07 (UTC)

Enig i at vi bør kjøre en konsis linje. Ønsker ikke å drive noe særlig overdreven sensur though, så retningslinjene bør være enkle å forstå og uten for mange påheng og unntak. Noe ala "faglig stuff er bra, andre ting har lite her å gjøre." Tar gjerne i mot konkrete forslag til ordlyd på denne siden, men tenker ikke å åpne den for redigering siden ordlyden bør diskuteres før den settes i verk. Når det gjelder enkle artikler om SEM og TEM og sånt synes jeg det er helt topp! Jeg mener ikke at nanowikien trenger å være en wikipediakopi, men mange slike tekniske ting gjør det ingenting om man får forklart fra flere synspunkter. Jeg kommer ikke til å slette noe fagrelevant innhold så lenge det ikke er direkte løsningsforslag på øvingsopplegg i noen fag. Forøvrig veldig bra innsats Marius :) --[[Bruker:Goranb|Goranb]] 27. okt 2008 kl. 18:28 (UTC)

Ok. Men det jeg også lurer litt på var om vi/jeg skulle legge alt av mikroskopiting innunder måleteknikk, eller om de skulle få lov til å være egne artikler? Kan godt flytte det i og med at jeg har funnet ut hvordan man omdirigerer sider og gjort en del av det... --[[Bruker:Mariusuv|Mariusuv]] 28. okt 2008 kl. 07:45 (UTC)

Du tenker vel på nanotools, og ikke måleteknikk? Synes i alle fall det er greit at konsepter som er aktuelt for flere fag har sine egne artikler, så kan man heller linke til dem fra de forskjellige fagene. På den måten er det også enklere å søke seg fram til det man ser etter. --[[Bruker:Goranb|Goranb]] 28. okt 2008 kl. 10:20 (UTC)

Jeg synes det kan være en liten gradient på disse tingene, hvis det er naturlig at beskrivelse av ett eller annet emne kommer under et spesifikt fag begynner man med å skrive den der. Hvis den blir ''for'' stor, eller stor nok, kan den legges i et eget dokument, dette kan gjerne også skje dersom den begynner å bli aktuell under flere fag. Løsningen som wikipedia bruker er å ha et relevant utdrag fra en hovedartikkel, dersom denne finnes. I vårt tilfelle kan det f.eks. finnes en egen artikkel om SEM, også kan man ha relevante utdrag eller oppsummeringer av denne under fag som halvledertek, nanotools og nanomat, med link til hovedartikkelen.

--[[Bruker:Beckwith|beckwith]] 28. okt 2008 kl. 12:11 (UTC)

Når det gjelder kloning fra wikipedia, synes jeg at dersom man kun ender med å ta "klipp ut og lim inn" direkte fra wikipedia er det noe unødvendig, men med en gang man kan bidra med litt eksformasjon (forkasting av unyttig informasjon uten å miste meninga), om det er oversetting, omskriving, oppklaring eller oppsummering, så er det helt greit å ha artikkeler som overlapper med wikipedia o.l.

--[[Bruker:Beckwith|beckwith]] 28. okt 2008 kl. 12:23 (UTC)

Ang. kloning fra wikipedia, så er dette '''ulovlig''', så den saken er ute av verden. Ta heller å link til artikkelen, evt. siter og referer.

--[[Bruker:Vidarton|Vidarton]] 4. nov 2008 kl. 00:02 (UTC)

Ulovlig? Siterer: "All of the text in Wikipedia, and most of the images and other content, is covered by the GNU Free Documentation License (GFDL). Contributions remain the property of their creators, while the GFDL license ensures the content is freely distributable and reproducible. (See the copyright notice and the content disclaimer for more information.)".

Jeg tolker dette som at innholdet kan brukes som man ønsker, men at det bør refereres tilbake til wikipedia hvis det er direkte rip-off (som det står i copyright notice). Jeg tror uansett vi er enige om fremgangsmåten her.

--[[Bruker:Beckwith|beckwith]] 4. nov 2008 kl. 10:50 (UTC)

Ønsker meg konkrete forslag til ordlyd. -[[Bruker:Goranb|Goranb]] 4. nov 2008 kl. 12:15 (UTC)

Har fiksa og ordna litt. Tilbakemelding? --[[Bruker:Goranb|Goranb]] 12. nov 2008 kl. 15:39 (UTC)

== Engelsk? ==

Vi har nå invitert en hel del forelesere til å bidra på wikien, og jeg fikk respons fra Pawel i dag. Han stilte spørsmålet som har lurt i bakhodet mitt siden oppstarten; skal wikien være utelukkende på norsk?

Min personlige mening er nei. En veldig stor andel av undervisningen vår foregår allerede på engelsk så jeg tror ikke noen vil ha problemer med det. Hvordan løser vi så eventuelt en tospråklig wiki rent praktisk? Uten å tenkt fryktelig mye på det, foreslår jeg at hvis det finnes en engelsk artikkel kan den tilsvarende tittelen på norsk inneholde en link til den engelske artikkelen og vice versa. Kjør diskusjon!

Pawel foreslo forøvrig å gjøre det å skrive artikler på nanowikien til en del av bionanoprosjektet, det synes jeg er en super idé som virkelig kan få fart på det faglige innholdet.

--[[Bruker:Audunnys|Audunnys]] 24. nov 2008 kl. 08:50 (UTC)

For det første - veldig godt forslag fra Pawel. Det håper jeg vi får gjennomført! Når det gjelder språk er det alltid litt rart å skulle ha en multispråklig nettportal, men jeg ser absolutt behovet for engelsk. Samtidig er det nok ikke noe triks å skulle tvinge alle til å skrive engelsk hele veien, så vi må nok akseptere dette. Foreslår at vi gjør som du foreslår - vi godtar artikler på både norsk og engelsk og linker disse til hverandre.
--[[Bruker:Goranb|Goranb]] 24. nov 2008 kl. 10:08 (UTC)

Hadde vært en fordel om flere ble engasjert nok til å skrive litt her en gang i blandt, så Pawels ide er god. (Jeg har mistet litt inspirasjon i det siste...) Ellers er vel en tospråklig versjon ikke så dumt i alle fall hvis man kjører link-versjonen, men da må det jo selvfølgelig skrives på engelsk også, men det er jo ikke verdens undergang. --[[Bruker:Mariusuv|Mariusuv]] 24. nov 2008 kl. 15:10 (UTC)

== Bilder og opphavsrett ==

Vi kan ikke laste opp opphavsbeskyttet materiale uten tillatelse. [http://no.wikipedia.org/wiki/Hjelp:Bildeopplasting Wikipedia] kjører den strenge linja - alt må være fritt tilgjengelig for at det skal kunne lastes opp. Hvordan skal vi gjøre det? Er vi fornøyde så lenge noen sender en mail til rettighetshaver og får OK? --[[Bruker:Audunnys|Audunnys]] 13. des 2008 kl. 09:42 (UTC)

Da er det vel lov å bruke bilder fra Wikipedia? [[Bruker:Mariusuv|Mariusuv]] 13. des 2008 kl. 17:15 (UTC)

: Nå har jeg ikke studert Wikipedias lisenser, men såvidt jeg har forstått så er det som ligger under creative commons fritt tilgjengelig for all bruk og modifisering, altså er svaret ja. (Forøvrig er det veldig greit å bruke innrykk med : (kolon) i diskusjoner, så ser vi hvem som svarer på hva) --[[Bruker:Audunnys|Audunnys]] 13. des 2008 kl. 23:08 (UTC)

Diskusjon:Retningslinjer for nanowiki

2008-12-13T09:42:42Z

Audunnys: Glemte signatur

Diskusjon:Retningslinjer for nanowiki

2008-12-13T09:42:16Z

Audunnys: /* Bilder og opphavsrett */ ny seksjon

TKP4115

2008-12-12T00:55:46Z

Audunnys: TKP4115 flyttet til TKP4115 - Overflate- og kolloidkjemi

#REDIRECT [[TKP4115 - Overflate- og kolloidkjemi]]

TKP4115 - Overflate- og kolloidkjemi

2008-12-12T00:55:46Z

Audunnys: TKP4115 flyttet til TKP4115 - Overflate- og kolloidkjemi

{{Infobox
|Fakta vår 2009
|*Foreleser: Gisle Øye
*Stud-ass: Silje Haga og Thor Christian Hobæk
*Vurderingsform: Skriftlig eksamen
*Eksamensdato: 22. mai
}}

[[Kategori:Obligatoriske emner]]
[[Kategori:Fag 4. semester]]
[[Kategori:Fag]]

Hovedside

2008-12-03T07:33:30Z

Audunnys:

Hovedside

2008-12-03T06:59:33Z

Audunnys:

Hovedside

2008-12-03T06:59:09Z

Audunnys:

Diskusjon:Retningslinjer for nanowiki

2008-11-24T08:50:44Z

Audunnys: /* Engelsk? */ ny seksjon

TFE4180 - Halvleder komponent- og kretsteknologi

2008-10-25T09:50:49Z

Audunnys: /* Tips */

{{Infobox
|Fakta høst 2008
|*Foreleser: Bjørn-Ove Fimland
*Stud-ass: Magnus Breivik
*Vurderingsform: Skriftlig eksamen
*Eksamensdato: 10. desember
}}

{{Infobox
|Øvingsopplegg høst 2008
|* Antall godkjente: 8/12
* Innleveringssted: Utenfor A383, Elektrobygget
* Frist: Mandager 16:00
}}

{{Infobox
|Lab høst 2008
|* Skal lage en Hall-bar
*4 labøkter av 4 timer
*Avsluttende raport leveres for godkjenning
}}

Emnet skal formidle innsikt i halvleder tynnfilmteknologi for fremstilling av elektroniske og fotoniske komponenter og integrerte kretser.

== Kort om faget ==
Hoveddelen av emnet er dedikert prosessering av halvlederkomponenter og integrerte kretser, som filmdeponering, ioneimplantasjon, fotolitografi og avansert litografi, etsing, metallisering, trådbonding og pakking. Det vil også ble gjennomgått krystallgroing fra smelte og epitaksielle deponeringsteknikker (dampfase-, væskefase- og molekylstråle-epitaksi). Halvleder heterostruktur og supergitter. Karakterisering av halvledere med elektriske målinger (resistivitet, mobilitet, dopekonsentrasjoner), diffraksjonsmetoder ([http://en.wikipedia.org/wiki/X-ray_crystallography XRD], [http://en.wikipedia.org/wiki/RHEED RHEED], [http://en.wikipedia.org/wiki/Low-energy_electron_diffraction LEED]), ionestråle-baserte teknikker ([http://en.wikipedia.org/wiki/Secondary_ion_mass_spectrometry SIMS]) og mikroskopi ([http://en.wikipedia.org/wiki/Optical_microscope OM], [http://en.wikipedia.org/wiki/Scanning_Electron_Microscope SEM], [http://en.wikipedia.org/wiki/Transmission_electron_microscopy TEM], [http://en.wikipedia.org/wiki/Scanning_tunneling_microscope STM], [http://en.wikipedia.org/wiki/Atomic_force_microscope AFM]).

== Lab ==
Labben består av fire deler som går ut på å lage og måle en Hallbar. Tenkikker som blir brukt er fotolitografi, mikroskop, elektronmikroskop, etsing, og måling av [http://en.wikipedia.org/wiki/Hall_effect Hall effekten].

=== Rapporten ===
Rapporten skal ha en vitenskapelig oppbygning som beskrevet i infofilen. Hele målet er finnne dopetype og ladningsbærerkonsentrasjon. Videre kan man si noe om mobiliteten og hvordan denne gir et uttrykk for feil i krystallstrukturen.

I teorien bør man ha med ting som: hall effekt, geometrisk magnetoresistans, hall motstand og andre ting man diskuterer i rapporten.

Under Eksprimentdelen går det fint å henvise til dokumentet ''Lab_practical.pdf'', men da må denne legges ved. Viktig å få med hvilken fotoresist og maske man brukte, og parametrene i fotolitografiens ti trinn.

Under Resultater bør man ha med dimensjoner på hallbaren, en tabell over høydemålinger gjort med talysteppen, samt alle grafene du fikk fra målingene. Mangus (vit.ass) sa at man kun trengte å se på gjennomsnittsgrafen i figurene.

Det er viktig å ha med feilkilder som: loddingen og at varme kan ødelegge dopingen, og vis dere så noe rart under inspeksjonen av hallbaren etter fotolitografien.

Se [[Rapport]] for mer info om hvordan skrive en vitenskapelig rapport.

==== Tips ====
* Vi har benyttet evaporation på alle prøvene i år. Evaporation/Damping er mer anisotrop enn sputtering, som er fordelaktig ved lift-off på fotoresist med undercut

* Hall-måle-maskin: Vi benyttet oss av "7500/7700 & 9500/9700 Series". Husker ikke hvilken av de, men de har felles manual.

* Det man ofte er mest interessert i er dopekonsentrasjon. Videre så er dopetype (n, p) interessant for dere, siden dere i utgangspunktet ikke vet hvilken som er hvilken. Videre så vil mobiliteten fortelle noe om kvaliteten på krystallen, så det er interessant å sammenligne denne med forventet verdi fra litteraturen. For beregning selv kan det være interessant å sml dopekonsentrasjon og mobilitet med IV-kurven via <math>J=\sigma \cdot E</math>. Ellers er vel igrunnen de fleste verdiene allerede gitt av hall-målingsprogrammet...

* r-parameteren er et tall for å relatere målt mobilitet (Hall-mobilitet) til faktisk mobilitet (og dermed driftshastigheten i materialet). Om man ikke vet hva denne er så er det best å sette den lik 1 og heller nevne det i teksten.

== Eksterne linker ==
*[http://www.ntnu.no/portal/page/portal/ntnuno/AlleEmner?rootItemId=22934&selectedItemId=31007&emnekode=TFE4180 NTNUs fagbeskrivelse]
*[http://www.ntnu.no/studieinformasjon/timeplan/h08/?emnekode=TFE4180-1&valg=emnekode&bokst= Timeplan Høst08]

[[Kategori:Obligatoriske emner]]
[[Kategori:Fag 5. semester]]
[[Kategori:Fag]]

TFE4180 - Halvleder komponent- og kretsteknologi

2008-10-25T09:49:22Z

Audunnys: /* Rapporten */

{{Infobox
|Fakta høst 2008
|*Foreleser: Bjørn-Ove Fimland
*Stud-ass: Magnus Breivik
*Vurderingsform: Skriftlig eksamen
*Eksamensdato: 10. desember
}}

{{Infobox
|Øvingsopplegg høst 2008
|* Antall godkjente: 8/12
* Innleveringssted: Utenfor A383, Elektrobygget
* Frist: Mandager 16:00
}}

{{Infobox
|Lab høst 2008
|* Skal lage en Hall-bar
*4 labøkter av 4 timer
*Avsluttende raport leveres for godkjenning
}}

Emnet skal formidle innsikt i halvleder tynnfilmteknologi for fremstilling av elektroniske og fotoniske komponenter og integrerte kretser.

== Kort om faget ==
Hoveddelen av emnet er dedikert prosessering av halvlederkomponenter og integrerte kretser, som filmdeponering, ioneimplantasjon, fotolitografi og avansert litografi, etsing, metallisering, trådbonding og pakking. Det vil også ble gjennomgått krystallgroing fra smelte og epitaksielle deponeringsteknikker (dampfase-, væskefase- og molekylstråle-epitaksi). Halvleder heterostruktur og supergitter. Karakterisering av halvledere med elektriske målinger (resistivitet, mobilitet, dopekonsentrasjoner), diffraksjonsmetoder ([http://en.wikipedia.org/wiki/X-ray_crystallography XRD], [http://en.wikipedia.org/wiki/RHEED RHEED], [http://en.wikipedia.org/wiki/Low-energy_electron_diffraction LEED]), ionestråle-baserte teknikker ([http://en.wikipedia.org/wiki/Secondary_ion_mass_spectrometry SIMS]) og mikroskopi ([http://en.wikipedia.org/wiki/Optical_microscope OM], [http://en.wikipedia.org/wiki/Scanning_Electron_Microscope SEM], [http://en.wikipedia.org/wiki/Transmission_electron_microscopy TEM], [http://en.wikipedia.org/wiki/Scanning_tunneling_microscope STM], [http://en.wikipedia.org/wiki/Atomic_force_microscope AFM]).

== Lab ==
Labben består av fire deler som går ut på å lage og måle en Hallbar. Tenkikker som blir brukt er fotolitografi, mikroskop, elektronmikroskop, etsing, og måling av [http://en.wikipedia.org/wiki/Hall_effect Hall effekten].

=== Rapporten ===
Rapporten skal ha en vitenskapelig oppbygning som beskrevet i infofilen. Hele målet er finnne dopetype og ladningsbærerkonsentrasjon. Videre kan man si noe om mobiliteten og hvordan denne gir et uttrykk for feil i krystallstrukturen.

I teorien bør man ha med ting som: hall effekt, geometrisk magnetoresistans, hall motstand og andre ting man diskuterer i rapporten.

Under Eksprimentdelen går det fint å henvise til dokumentet ''Lab_practical.pdf'', men da må denne legges ved. Viktig å få med hvilken fotoresist og maske man brukte, og parametrene i fotolitografiens ti trinn.

Under Resultater bør man ha med dimensjoner på hallbaren, en tabell over høydemålinger gjort med talysteppen, samt alle grafene du fikk fra målingene. Mangus (vit.ass) sa at man kun trengte å se på gjennomsnittsgrafen i figurene.

Det er viktig å ha med feilkilder som: loddingen og at varme kan ødelegge dopingen, og vis dere så noe rart under inspeksjonen av hallbaren etter fotolitografien.

Se [[Rapport]] for mer info om hvordan skrive en vitenskapelig rapport.

==== Tips ====
* Vi har benyttet evaporation på alle prøvene i år. Evaporation/Damping er mer anisotrop enn sputtering, som er fordelaktig ved lift-off på fotoresist med undercut

* Hall-måle-maskin: Vi benyttet oss av "7500/7700 & 9500/9700 Series". Husker ikke hvilken av de, men de har felles manual.

* Det man ofte er mest interessert i er dopekonsentrasjon. Videre så er dopetype (n, p) interessant for dere, siden dere i utgangspunktet ikke vet hvilken som er hvilken. Videre så vil mobiliteten fortelle noe om kvaliteten på krystallen, så det er interessant å sammenligne denne med forventet verdi fra litteraturen. For beregning selv kan det være interessant å sml dopekonsentrasjon og mobilitet med IV-kurven via J=sigma*E. Ellers er vel igrunnen de fleste verdiene allerede gitt av hall-målingsprogrammet...

* r-parameteren er et tall for å relatere målt mobilitet (Hall-mobilitet) til faktisk mobilitet (og dermed driftshastigheten i materialet). Om man ikke vet hva denne er så er det best å sette den lik 1 og heller nevne det i teksten.

== Eksterne linker ==
*[http://www.ntnu.no/portal/page/portal/ntnuno/AlleEmner?rootItemId=22934&selectedItemId=31007&emnekode=TFE4180 NTNUs fagbeskrivelse]
*[http://www.ntnu.no/studieinformasjon/timeplan/h08/?emnekode=TFE4180-1&valg=emnekode&bokst= Timeplan Høst08]

[[Kategori:Obligatoriske emner]]
[[Kategori:Fag 5. semester]]
[[Kategori:Fag]]

Diskusjon:Linjeforening

2008-10-23T15:05:54Z

Audunnys:

Kan admin slette denne siden? --[[Bruker:Mariusuv|Mariusuv]] 23. okt 2008 kl. 14:29 (UTC)

Jeg vil gjerne la folk diskutere [[retningslinjer_for_nanowiki|retningslinjene]] noen dager før vi evt begynner å slette sider. --[[Bruker:Audunnys|Audunnys]] 23. okt 2008 kl. 15:05 (UTC)

Diskusjon:Kjellerstyret

2008-10-22T19:43:30Z

Audunnys:

Hører dette her hjemme på nanowikien?

--[[Bruker:Beckwith|beckwith]] 15. okt 2008 kl. 12:05 (UTC)

Si det... Det må i alle fall være alt eller ingenting. --[[Bruker:Mariusuv|Mariusuv]] 15. okt 2008 kl. 17:04 (UTC)

Ja, og i dette tilfellet synes jeg ingenting er et mer passende alternativ. Det er tre grupper som er logiske å ha her: Fagteamet, siden de har faglige tilknytninger, infodep, siden de drifter siden og er de man må kontakte hvis noko er gale, og Timini, med en minimal beskrivelse slik siden er i dag. Resten finner man på Timinisiden. Så jeg synes både Timini Idrett og kjellerstyret sine sider bør slettes.

--[[Bruker:Beckwith|beckwith]] 18. okt 2008 kl. 08:35 (UTC)

For å oppsummere dette så er det da kun nødvendig med fag og utveksling og litt til som [[Linjeforening]]? Ikke ment sarkastisk, men kan vel leses sånn, så jeg bare vil ha opp det at noen burde drive 'sensur' etter en mal. --[[Bruker:Mariusuv|Mariusuv]] 18. okt 2008 kl. 13:53 (UTC)

Tror jeg er enig med Kai her. Wikien er ment som en fagwiki uten å egentlig være tilknyttet Timini på annen måte enn at det er infodep som drifter den og at det i utgangspunktet er timinis medlemmer som har skrivetilgang. Flere meninger om saken? --[[Bruker:Audunnys|Audunnys]] 18. okt 2008 kl. 14:08 (UTC)

Så da er det bare fag og utveksling nanowikien tar for seg. Da er det vel en mal for innhold. --[[Bruker:Mariusuv|Mariusuv]] 18. okt 2008 kl. 14:23 (UTC)

Det er forsåvidt en del gode poenger som dukker opp her. Vi har aldri definert noen retningslinjer for hva denne wikien skal inneholde og bør derfor være litt forsiktig med å drive sensur. Det man i alle fall kan si er at dette ikke er en Timiniwiki, så alle timini-team som presenteres her må understrekes at de tilhører linjeforeningen Timini. Man kunne eventuelt vurdert å opprette en kategori:timini og putte slike ting der? Jeg er forøvrig ENIG i at Kjellerstyret ikke har noe i nanowikien å gjøre, jeg ønsker bare å påpeke at vi bør ha klare retningslinjer for hva som skal og ikke skal være her før vi sletter noe. --[[Bruker:Goranb|Goranb]] 19. okt 2008 kl. 15:55 (UTC)

Åja,har visst misforstått litt jeg da=/
Tenkte at siden logoen til sida er Timinilogoen(eller det jeg forbinder med timini),ville det være ok å legge ut tiministuff her også...
Men kan slette sida, no big deal. Bare kjeda meg litt en dag....=P
Forøvrig enig med at noen retningslinjer hadde vært fint!

Fikk forresten ikke til å slette,jeg,så nå er det bare en overskrift...

Når denne da er borte kanskje også linjeforening skulle ha tatt seg en tur til et annet sted, og nabla få seg litt annet innhold? --[[Bruker:Mariusuv|Mariusuv]] 21. okt 2008 kl. 21:51 (UTC)

Vi diskuterte litt retningslinjer for wikien på infodepmøtet i dag, og Gøran kommer til å legge ut ei side for diskusjon ganske snart.--[[Bruker:Audunnys|Audunnys]] 22. okt 2008 kl. 19:43 (UTC)

Diskusjon:Kjellerstyret

2008-10-18T14:08:49Z

Audunnys:

TDT4105

2008-10-05T15:39:38Z

Audunnys: TDT4105 flyttet til TDT4105 - IT Grunnkurs

#REDIRECT [[TDT4105 - IT Grunnkurs]]

TDT4105 - IT Grunnkurs

2008-10-05T15:39:38Z

Audunnys: TDT4105 flyttet til TDT4105 - IT Grunnkurs

== Om faget ==

Faget TDT 4105 er et innføringsfag i informasjonsteknologi. For MTNANO betyr dette å lære enkel HTML og Matlab.

== Lærebøker ==

Tilleggskompendiet (til matlab) er nyttig å ha. Ellers finnes det meste på internett. For HTML er [http://w3schools.com w3schools] en fin side.

Læreboken (teoriboken) kan være overflødig for de med noe IT-kunnskaper, men inneholder en del begreper som kan være lure å få med seg når eksamen nærmer seg. Denne boken kan enkelt skaffes brukt fra eldre studenter.

Matlab kan skaffes fra [http://infoweb.ntnu.no/programmer/generelt/progdistinfo.html progdist], og NTNUstudenter får gratis lisens.

[[Kategori:Obligatoriske emner]]
[[Kategori:Fag 1. semester]]
[[Kategori:Fag]]

TIØ4258 - Teknologiledelse

2008-09-29T22:42:27Z

Audunnys: Ny side: Kategori:Obligatoriske emner Kategori:Fag 6. semester Kategori:Fag

[[Kategori:Obligatoriske emner]]
[[Kategori:Fag 6. semester]]
[[Kategori:Fag]]

TFE4215 - Faststoff-materialer og nanostrukturer

2008-09-29T22:41:51Z

Audunnys: Ny side: Kategori:Obligatoriske emner Kategori:Fag 6. semester Kategori:Fag

[[Kategori:Obligatoriske emner]]
[[Kategori:Fag 6. semester]]
[[Kategori:Fag]]

TKJ4215 - Statistisk termodynamikk i kjemi og biologi

2008-09-29T22:40:10Z

Audunnys:

{{Infobox
|Statistisk termodynamikk i kjemi og biologi
|Faglærer: Per-Olof Åstrand

Stud.ass.: Magnus Ringholm
}}

Statistisk termodynamikk (også kjent som statistisk mekanikk) tar som mål å forklare mye av termodynamikken ut fra statistiske grunnprinsipp. Fra våren 2009 vil statistisk termodynamikk bli undervist i 4. semester.

== Erfaringer ==
Statistisk termodynamikk forklarer alt. Fra bunnen. Bare husk at hvis <math>N</math> objekter skal ordnes blir antall mulige ordninger <math>N!</math> dersom partiklene er distinkte, altså at de kan skilles fra hverandre, eller <math>\frac{N!}{n_1!\cdot n_2!\cdot ... \cdot n_i!}</math>, dersom hver av de <math>n_i</math> kategoriene er distinkt fra de andre <math>n_{i-1}</math> kategoriene, men objektene i hver kategori ikke er distinkte.

For ''n'' partikler som kan fordeles i ''N'' tilstander blir antall mulige konfigurasjoner da <math>\frac{N!}{n!\cdot (N-n)!}</math>

[[Kategori:Obligatoriske emner]]
[[Kategori:Fag 5. semester]]
[[Kategori:Fag]]