Topographic Contrast in Force Modulation Atomic Force Microscopy Images

Topographic influences on force modulation microscopy (FMM) amplitude image contrasts have been investigated. Experimental results and a simple model analysis demonstrate that the amplitude has a close relevance to the x-derivative of sample topography. When the tip sample is in a single-point contact and the mechanical properties of the sample are homogeneous, the contrasts of the amplitude and x-derivative topography are almost the same. In addition, the amplitude contrast is reversed when the scan direction is opposite. When the tip sample is in a multipoint contact, the amplitude at the multipoint contact region increases markedly and the scan-direction relevant contrast reversion is still distinguishable. These results can help in the interpretation of FMM data accurately.