Unoccupied electronic states of a graphite surface as observed by local tunnelling spectroscopy

Abstract

We have investigated the empty electronic states of an oriented (0001) cleaved graphite sample with the STM in the energy range of EF<EEF+5eV. The local spectra obtained exhibit a three-peak structure at 1.5, 2.7 and 3.7eV above EF. The energy positions of the highest and the lowest fit well with that of the graphite interlayer (surface and bulk) state and a Π-antibonding state, in agreement with recent predictions by Selloni, Carnevali, Tosatti and Chen. The nature of the middle peak is less clear, and could be defect-related. © 1987 IOP Publishing Ltd.