Crystal‐field model study of the xenon hexafluoride molecule. III. Electronic transitions and band shapes

Abstract

The application of a two‐electron crystal‐field model to the electronic structure of xenon hexafluoride is extended to include the calculation of oscillator strengths for absorption transitions to the largely spin singlet and the largely spin triplet excited states. Band shapes are calculated in terms of their spectral moments by obtaining vibrational energies and wavefunctions for the mixed quadratic‐quartic potential energy functions calculated from the crystal‐field model. The key experimental features of the absorption spectrum of the vapor are reproduced, namely the pronounced red shift and the increased bandwidth with rising temperature. The over‐all similarity of the vapor spectrum to that of the isovalent hexahalotellurate (IV) complexes in solids in noted. It is concluded that the experimental data of Claassen, Goodman, and Kim are compatible with the pseudo‐Jahn‐Teller model of Gillespie as developed by Bartell and Gavin and by Wang and Lohr, and that the data do not require the use of the electronic isomers model of Goodman, although the latter model is not excluded.