Line Shape of the A Band of s2 Configuration Ions in Alkali Halide Crystals

Abstract

A systematic investigation of the line shape of the A band of several ions with the s2 configuration dissolved in alkali halides has been made on KCl:In+, KBr:In+, KCl:Sn2+, KBr:Sn2+, KI:Sn2+, RbCl:Sn2+, KCl:Tl+, KBr:Tl+, KI:Tl+, and KBr:Pb2+ crystals. A temperature sensitive doublet structure was observed for In+ and Sn2+ doped crystals and for KCl:Tl+, while a single band, which is asymmetric at high temperatures, was observed for KBr:Tl+ and KBr:Pb2+. The temperature dependence of the line shape supports Toyozawa and Inoue's theory in which the fine structure is ascribed to the dynamical Jahn–Teller effect. A discussion is given of the importance of quadratic electron–lattice interaction and its effect on the asymmetry of the line shape.