PHOTOEMISSION, AUTOIONIZATION, AND X-RAY-ABSORPTION SPECTROSCOPY OF ULTRATHIN-FILM C60 ON AU(110)

The occupied and unoccupied electronic states of C60 have been studied for single monolayer and multilayer coverages on Au(110). Only the el ectronic structure of the first layer, which is chemisorbed, is change d by the interaction with the substrate, due to hybridization with the possibility of charge transfer. There is no measurable bonding intera ction with the second layer, which has essentially the same electronic structure as the thick film. The unoccupied electronic states below t he ionization level are shown to be largely localized around the C60 m olecule. The energy levels of the molecules not in direct contact with the substrate are referenced to the vacuum level.