Forskjell mellom versjoner av «Surface Probe Microscopy»
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==Surface forces== |
==Surface forces== |
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| − | Three regions can be distinguished on the potential energy curve of to solid surfaces brought into contact. |
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| + | Three interaction zones: |
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| − | For larger distances, the non-contact mode, where the attractive forces dominate. These are for example caused by the Coulombic electrostatic forces, if the surfaces are of differernt charge. |
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| + | *Non-contact zone: Only long range forces are experienced. Usually attractive. Coulomb forces - strongest long range forces (can be repulsive as well). |
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| − | At distances smaller than the distance at which the potential enrgy is zero, one can define the contact mode. The repulsive forces are dominating and the attractive ones negligible. These are caused by steric hindrance, or the Debye/diffuse double layers for example. |
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| + | *Semi-contact region: Similar magnitude of repulsive and attractive forces. |
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| − | In between these two regions there is the semi-contact region. |
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| + | *Contact zone: Distances smaller than the distance at which the potential energy is zero. Attractive forces are negligible. Short range repulsive forces dominate. |
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| + | The forces: |
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| + | * Strong long-range forces: Coulomb forces |
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| + | * Shorter distances: Van der Waals (kålloidal kemmistri!) These forces decay rapidly, with <math>f \propto d^{-7}</math> |
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| + | * Strong short range forces: Overlapping of electron shells (steric hindrance), Debye/diffuse double layers for example. |
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==Resolution== |
==Resolution== |
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Nåværende revisjon fra 24. mai 2009 kl. 12:34
Scaning probe microscopy is a field where microstructural information can be obtained by bringing a sharp, needle-shaped solid probe into close proximity to the surface we want to study. This method can give information about the surface structure and surface properties.
Surface forces
Three interaction zones:
- Non-contact zone: Only long range forces are experienced. Usually attractive. Coulomb forces - strongest long range forces (can be repulsive as well).
- Semi-contact region: Similar magnitude of repulsive and attractive forces.
- Contact zone: Distances smaller than the distance at which the potential energy is zero. Attractive forces are negligible. Short range repulsive forces dominate.
The forces:
- Strong long-range forces: Coulomb forces
- Shorter distances: Van der Waals (kålloidal kemmistri!) These forces decay rapidly, with <math>f \propto d^{-7}</math>
- Strong short range forces: Overlapping of electron shells (steric hindrance), Debye/diffuse double layers for example.
Resolution
The probe tip radius limits the resolution of the image and it will be at least one order of magnitude bigger than the atom spacings. But it can still give atomic resolution.
