Assignment of the Raman active lattice vibrations in various phases of 1,2,4,5 tetrabromobenzene and 1,2,4,5-tetrachlorobenzene crystals

Results of polarized Raman spectroscopy are reported and used to obtain complete assignment of the optical lattice modes of 1,2,4,5-tetrabromobenzene crystals for both the beta and gamma phases. Similar information is provided for the beta phase of 1,2,4,5-tetrachlorobenzene crystal. The results are compared with lattice-dynamics calculations. Discrepancies with previously reported measurements and calculations are discussed and rationalized. The Journal of Chemical Physics is copyrighted by The American Institute of Physics