Lifetime effects in low-stage intercalated graphite systems

Based upon a superlattice model for graphite intercalated compounds (GIC's), we present in this paper a detailed calculation of the lifetime of a conduction electron in a stage-1, acceptor-type GIC. Both intraband and interband processes, as well as intervalley processes, are included in this calculation. We find that it is very important to include the dynamic screening in the scheme, because the Coulomb interaction can generate plasmons that provide an efficient way for electrons to decay. The calculated electronic lifetime is then applied to the examination of the broad edge structure found in optically induced interband transitions. There, only partial success is found, possibly because of inaccurate determination of the Fermi energy. Improvements of our present calculation are suggested.