High-pressure Brillouin study of solid HBr at pressures up to 7 GPa

Abstract

High-pressure Brillouin scattering measurements have been carried out in orientationally disordered (OD) phases I and I′ of solid HBr, which yielded the first determination of acoustic velocities for all directions, the refractive index, the polarizability, the density, adiabatic elastic constants (C11, C12, and C44), bulk modulus, and the elastic anisotropy as a function of pressure up to 7 GPa and at room temperature. The I→I′ phase transition in solid HBr was confirmed on the discontinuous pressure dependence at P=2.3 GPa for average errors of the least-squares fit by the analysis of in situ Brillouin spectroscopy. These elastic properties of solid HBr are compared with recent results in the OD phase I of solid HCl. We suggest that the form of the potential energy function for intermolecular forces in solid HBr is similar to that in HCl.