Ultraviolet Absorption of Insulators. V. The Cesium Halides

Abstract

The intrinsic ultraviolet spectra of the simple cubic Cs halides measured by Eby, Teegarden, and Dutton are analyzed into exciton and scattering parts. The effects of configuration interaction on spin-orbit splittings are discussed semiquantitatively, and specific mechanisms are proposed. It is shown that the conduction bands can be separated into a lowest $s$-like band and higher $d$-like bands in CsCl and CsBr. In CsI the bands may overlap. The stability of the extra excitons appears to be reduced by configuration interaction in CsI.