Lattice dynamic analysis of Raman data from tin tetrabromide: Chains at high pressures

Abstract

A lattice dynamic model of chains of SnBr, molecules is developed to analyze previously published Raman data at high pressures. This model is used to evaluate both the intra-and intermolecular bonding in SnBr, up to about 10 GPa. The effective force constant associated with the intramolecular Sn-Br bond is found to increase in an approximately linear manner with pressure. The effective force contant of the intramolecular Br-Br bond shows a dramatic decrease of about 30% near 6 GPA, the pressure at which chains of molecules begin to form in SnBr, . The effective force constant associated with the intermolecular Br-Br bond rises linearly with pressure after the chains begin to form.