Infrared and Raman spectroscopy of graphite-ferric chloride

We present the first detailed study of the stage dependence of the IR- and Raman-active optic graphitic modes in a graphite acceptor intercalation compound. The general frequency upshift observed with increasing FeCl₃ concentration for all optic modes is interpreted to indicate an in-plane compression within the graphitic layers. An identification of the IR-active modes with bounding and interior graphite layers is made. A lineshape analysis of the IR spectra implies IR dipole moments corresponding to ～70% of the effective charge in the graphite bounding layers, independent of stage, and ～30% distributed among the graphite interior layers for stage n?3 compounds.