Luminescence of KI:Br and RbI:Br

Emission spectra and decay times of luminescence in KI and RbI containing small amounts of Br - ions are investigated. The Br - ions induce a reduction of Ex emissionin KI, but an enhancement of it in RbI. The Ex emission in KI seems to be of extrinsic origin. The luminescence center associated with the Ex emission in RbI:Br is deduced to be an STE of RbI perturbed by nearby Br - ions. The states responsible for the Ex and π emission bands in RbI are discussed in relation to the model of on- and off-center STEs.