In-plane intercalate lattice modes in graphite-bromine using Raman spectroscopy

Results of Raman scattering experiments associated with in-plane intercalate modes in graphite-bromine are reported. The spectra are interpreted in terms of models in which the molecular character of the bromine is retained and the molecular ordering of the intercalate layer is closely related to that in the layer structure of solid molecular bromine. The symmetry and group-theoretical analysis of several possible molecular arrangements are given. A large resonant enhancement of the Br₂ stretch mode is reported, which suggests molecular excitations for intercalated Br₂ at energies {}2.8 eV.