Self-trapped excitons in KI:Br and Rbl:Br

Abstract The effect of Br - ion impurities on the emission spectra and the decay times of the luminescence has been investigated in KI and RbI at low temperatures. Among the two π emission bands observed in the undoped sample, the higher energy one is enhanced in efficiency by the admixture of Br - ions. The decay time of the emission and its temperature dependence are almost unaffected by the doping. The results indicate that the Br - ion impurities induce a selective increase in the population of the one type between the two different self-trapped excitons (STEs). The structure of the two kinds of STEs is briefly discussed.