The Atomic Force Spectroscopy as a Tool to Investigate Surface Forces: Basic Principles and Applications

Atomic force microscopy (AFM) has been useful to investigate materials performance, processes, physical and surface properties at the nanometer scale. In addition to the standard AFM, which measures surface topography, many accessories have been developed to obtain specific additional information. In this chapter, we shall concentrate on atomic force spectroscopy (AFS), which derived from AFM and is used to measure surface forces through force curves. The latter curves have become an important tool to study materials properties, such as elasticity, surface charge densities and wettability. With AFS one probes interactions at the nanometer scale, especially van der Waals interactions and double-layer forces. A brief theoretical background is included, and we comment on the large variety of measurements involving AFS.