A model for the relative intensities among ion pair → valence transitions in the heavier halogens and rare gas halides

Abstract

The separated atom or ( J A M A J B M B) coupling scheme is applied to the electronic structure of both ion pair and valence states of the heavier halogens and rare gas halides. Relative transition moments from low vibrational levels of selected ion pair states to all the valence states and the resulting radiative lifetimes are derived. σ↔σ electron transfer between atomic orbitals is assumed for parallel transitions. Russell-Saunders coupling is used for the atomic or ionic basis functions in the reference model. Departures from the model arising from partial jj coupling in the halogen positive ions and from intramolecular electrostatic effects each produce characteristic changes in the relative intensities of the various fluorescent systems from a given ion pair state. The effect of J and M J state mixing between asymptotically degenerate valence states is discussed and ion pair → valence transition intensities are shown to be a sensitive function of this mixing.