Luminescence in KI:Tl

Abstract

Freshly cleaved single crystals of KI:TI containing various concentrations of Tl have been irradiated in a vacuum monochromator in the 2800-1100 A region at temper. atures between -140 and 45 °0. The relative luminescence efficiencies in the Tl absorption bands and the host crystal fundamental absorption show that energy is transferred from host crystal to impurity centre to produce luminescence at room temperatures. To the high energy side of a threshold, which appears to depend on activator concentration, the luminescence efficiency is superlinear above about 15 °0 for KI:Tl (0·0005%).