Inelastic Electron Scattering Spectroscopy of Graphite Intercalation Compounds

Abstract

In recent years graphite intercalation compounds have been the focus of much research because of their unique properties as a testing ground for fundamental studies of electrical and electronic properties, structural properties and phase transitions in quasi-two-dimensiona1 systems which are capable of a great deal of manipulation and control. The range of possible intercalation compounds is indicated in Figure 1. These materials consist of n layers of carbon atoms, covalently bonded within the plane in the usual graphite honeycomb lattice, between which are inserted planes of intercalants labeled X. The number of graphite layers, n, determines the stage of the compound. Well characterized compounds up to stage 5 or 6 can be easily prepared. X-ray and electron diffraction have been widely used to understand the structure of these compounds but many questions remain to be answered. This paper will concentrate on the fact that the intercalant always transfers charge to the graphite, acting either as an acceptor or a donor. Inelastic electron scattering spectroscopy has been used to study the electronic structure of the intercalant compounds and how it differs from graphite, as well as to determine the amount of charge transfer and the Fermi level position.