True Molecular-Scale Imaging in Atomic Force Microscopy: Experiment and Modeling

Abstract

Imaging with molecular-resolution achieved in tapping mode atomic force microscopy (AFM) opened a number of questions concerning image contrast and its variations. These issues are addressed in the interplay between experiment and theory in studies of polydiacetylene crystal. The dependence of image features on tip force and tip size has been revealed in theoretical simulations where bifurcation phenomenon played a major role. Experimental observations of periodical surface structures with molecular-scale single defects do not necessary prove true molecular-scale resolution because a number of periodical features seen in AFM images can originate in a result of bifurcation.