Carbon K-shell near-edge structure calculations for graphite using the multiple-scattering approach

Abstract

The near-edge absorption fine structure of carbon in graphite has been calculated using the multiple-scattering approach. The effects of both a neutral carbon absorber and taking into account the effect of the core hole by using a nitrogen (Z + 1) absorber atom are considered. The best agreement with experiment was obtained for the case of the nitrogen absorber and a cluster of 145 atoms, with the calculated near-edge structure (NES) containing the main features observed experimentally. A splitting near the onset of the -peak, similar to that seen experimentally, was found to occur in the calculated NES for one of the two inequivalent carbon atoms in the graphite structure. This splitting was not observed in the calculated NES for a single sheet of graphite, supporting the proposition that it only occurs in well ordered graphite. This result supports the proposition that the splitting originates from a sharp -peak and a dipole-allowed bandlike contribution associated to the branch of the free-electron-like interlayer states.