Anharmonicity of the stretching vibrations in SF₆

Abstract

A model for the anharmonic potential constants of the stretching vibrations of SF₆ is proposed and fitted to the available spectroscopic data. The model includes general terms arising from the stretching of individual bonds and the interaction between pairs of bonds. Explicit expressions are given for the ℒ-tensor elements and the relationship of normal-mode potential constants to internal coordinate force constants. The anharmonic constants derived from the present model predict band origins in good agreement with the high overtone and combination bands of stretching modes measured by Levene and Perry.