Growth of ordered C-60 islands on TiO2(110)

Abstract

Non-contact atomic force microscopy is used to study C-60 molecules deposited on the rutile TiO2(110) surface in situ at room temperature. At submonolayer coverages, molecules adsorb preferentially at substrate step edges. Upon increasing coverage, ordered islands grow from the decorated step edges onto the lower terraces. Simultaneous imaging of bridging oxygen rows of the substrate and the C-60 island structure reveals that the C-60 molecules arrange themselves in a centered rectangular superstructure, with the molecules lying centered in the troughs formed by the bridging oxygen rows. Although the TiO2(110) surface exhibits a high density of surface defects, the observed C-60 islands are of high order. This indicates that the C-60 intermolecular interaction dominates over the molecule-substrate interactions that may cause structural perturbations on a defective surface. Slightly protruding C-60 strands on the islands are attributed to anti-phase boundaries due to stacking faults resulting from two islands growing together.