Microscopic methods of characterization

AFM is simply a modified version of a scanning tunneling microscope. Unlike STM, it is applicable to both conducting and insulating surfaces. AFM works by scanning similar to STM. In AFM the tip is positioned at the end of a cantilever, a flap shaped much like a diving board. The tip touches the surface while scanning. The tip is repelled or attracted by the surface of the specimen and the cantilever beam deflects. The magnitude of the deflection is captured by a laser beam that reflects at an oblique angle from the very end of cantilever. A plot of laser deflection versus tip position on the sample surface provides the resolution of hills and valleys that constitute the topography of the surface. AFM works with the tip touching the sample (constant mode), or the tip can tap across the surface (tapping mode). The other measurements can be made using modifications of AFM. These include variation in surface micro friction with a lateral force microscope (LFM), orientation of magnetic domains with magnetic force microscope (MFM), deflection in elastic modulii on micro scale with force modulation microscope (FMM) and obtaining the differences between chemical formulations across the surface area with chemical force microscope (CFM).

Instrumentation and detail working of atomic force microscope is very complex, its schematic diagram is shown below.

For studying surface derivatization of biosensors.

For nano material texture and roughness.

For polymer analysis.

For surface analysis of metals in metallurgy.