INFLUENCE OF THE TOPOGRAPHY ON ADHESION MEASURED BY SFM

Surface properties such as adhesion are influenced by the surface topo graphy. This dependency complicates any quantitative investigation of the material constants. A simple and efficient model is used to calcul ate the influence of the topography on the pull of force determined by a scanning force microscope (SFM). In the model the SFM tip is repres ented by a sphere. The sample surface is modeled by two geometries: a step on a plane and a blister (spherical cap) on a plane. The atomic i nteraction between the tip and the surface is of the Lennard-Jones typ e. The theoretical results are compared with SFM-measurements on highl y oriented pyrolytic graphite (HOPG) in electrolytic environment. The calculations are in good agreement with the measured images.