Atomic Force Nano Microscope (AFM) is One of the Optical Devices

Abstract

In nanotechnology, from modern techniques of molecular simulation to a general framework for the interpretation of AFM images, especially  the analysis of atomic mechanisms that determine the force changes that the microscope measures and the contrast of the image, produces.

The recent advent of high-resolution imaging and force spectroscopy using atomic force mi- croscopy (AFM) in organic and inorganic solutions opens the way to imaging a wide variety of surfaces and their solvent structure. However, to take full advantage of the high resolution and provide signicant new analytical capability, a detailed understanding of the background contrast mechanisms that lead to atomic and molecular resolution is critical. Without a theory that connects the measured force to atomic models of the surface and tip of the microscope, the information that can be distilled from these measurements is limited. Molecular dynamics simulations show that the forces acting on the microscope tip result from the direct interaction between a tip and a surface and are entirely due to the structure of water around the tip and surface. The observed force depends on a tip structure, and the balance is between the mainly repulsive potential energy changes as the tip approaches the surface and the entropic increase, which is sterically prevented from occupying sites near the tip and the water surface. Under- standing the interplay of these various components that contribute to the force of microscopy measurements is critical to the interpretation of high-resolution images of solution interfaces.