Light scattering in graphite intercalation compounds

Abstract

Light scattering in graphite intercalation compounds gives key insights into the physics of these layered structures. In this chapter a review is presented of experimental Raman scattering studies and their interpretation based on models of the lattice dynamics of pristine and intercalated graphite. The periodic layer structure of intercalation compounds makes it possible to model the dynamical matrix by a Brillouin zone folding of the pristine graphite matrix. The stage dependence of the Raman-active modes is reported which correlates with a stage dependent strain. Resonant enhancement of the scattering cross-section permits observation of modes related to the intercalate layer. Explicit results are obtained for the internal modes of Br2 molecules in the graphite-Br2 system. Stage I alkali metal compounds show a lineshape of the Breit-Wigner-Fano form which implies a coupling between a sharp vibrational mode and a Ramanactive continuum. Second-order Raman scattering results for intercalated graphite are reported. A brief summary is also given on Raman scattering studies of intercalated graphite fibers, adsorbed molecules on graphite surfaces and ion-implanted graphite.