Fi-Stm Study of Fullerenes

Abstract

ABSTRACTAdsorption of C60, C70, C60(x)C70(1-x) and Sc2C84 on the Cu(111)1×1 and Ag(l11)1×1 surfaces has been investigated by field ion-scanning tunneling microscopy (FI-STM). On the Cu(111) and Ag(111) surfaces, the fullerene molecules are mobile on the terrace at room temperature and segregate to the steps to form linear chains then two-dimensional islands with a close-packed configuration. Upon monolayer adsorption, highly ordered 4×4 commensurate phases form in the case of the C60, C70 and C60(x)C70(1−x) adsorption on the Cu(111) surface, while close-packed hexagonal multiple phases, with nearest-neighbour distance equal to that of the bulk phase, form in the case of the C60 and Sc2C84 adsorption on the Ag(111) surface. These observations imply the competition between the adsorbate-adsorbate and adsorbate-substrate interactions. The intramolecular structures observed in the STM images of the C60 and C70 molecules in the Cu(111)-4×4 phases are analyzed to determine the adsorption geometry and are interpreted as the local density of the states of the C60 and C70 molecules.