Jahn-Teller and Reorientation Effects in the ESR Spectrum of the Self-Trapped Holes in Mixed Crystals AgBr_1-<i>x</i>Cl_<i>x</i>

Abstract

We report details of the ESR study of (AgBrCl 5 ) 4- in AgBr 0.001 Cl 0.999 crystals. Most of holes produced by the blue-light irradiation at low temperatures are self-trapped as the complex (AgCl 6 ) 4- . When the temperature is elevated, holes move in the crystal and are retrapped near Br ions forming (AgBrCl 5 ) 4- . Three principal values of the g tensor of (AgBrCl 5 ) 4- are obtained from the low temperature spectrum as indicative of a Jahn-Teller effect. The spectrum changes abruptly with increasing temperature. The high temperature spectrum shows that thermally activated reorientation occurs between two configurations of Jahn-Teller distortion.