Ultraviolet Absorption of the Mixed System KCl-KBr

Abstract

The ultraviolet absorption of thin evaporated layers and the edge absorption of single crystals of the mixed system KCl-KBr were measured at room temperature in the photon energy range from 6-11 ev. In the thin layers, both the ${\mathrm{Cl}}^{-}$ and the ${\mathrm{Br}}^{-}$ absorption bands are present in the mixtures and their heights depend on the relative concentrations of the two ions. The energy values of the bands generally shift with composition, although in contrast to all the other bands, the high-energy KBr band shifts very little. The results obtained for the low-energy absorption bands can be described by a simple semiclassical electron transfer model. The behavior of the high-energy KBr band is discussed.