THEORETICAL ATOMIC-FORCE-MICROSCOPY STUDY OF ADSORBED FULLERENE MOLECULES

The capability of atomic-force microscopy (AFM) to localize both indiv idual adsorbates and aggregates of adsorbed molecules was demonstrated a few years ago. More recently submonolayers of fullerene molecules d eposited on a gold Substrate have been imaged using such devices. In t his paper, simulations of the atomic force between a thin probe tip an d a set of adsorbed molecules is presented. The long-range part of the interaction is determined from a whole self-consistent procedure in w hich many-body effects are accounted for at all orders. In this descri ption the probe tip interacts with the molecules and the surface throu gh many-body dispersion forces. Short-range interactions are then incl uded by using an atom-atom semiempirical pairwise potential. Simulatio ns of AFM images of C-60 adsorbed molecules are presented in two diffe rent modes of imaging: the constant-tip-height mode and the constant-f orce mode.