PRESSURE DEPENDENCE OF THE LATTICE VIBRATIONS OF CRYSTALLINE BENZENE

Abstract

The Raman spectrum of crystalline benzene has been studied at temperatures between $77^{\circ} K$ and $300^{\circ} K$ and pressures up to 35 kbar. Lattice and internal vibrations have been observed for the orthorhombic and the monoclinic (high-pressure) phases. This paper reports primarily the results for the pressure-dependence of the gerade lattice vibrations in the orthorhombic phase at $77^{\circ} K$ . Theoretical calculations, based on an atom-atom intermolecular potential, are discussed. They include calculation of equilibrium crystal structure, elastic constants and pressure-dependence of structure and lattice frequencies. This work was supported in part by the Army Research Office (Durham) and by the United States Atomic Energy Commission.