Photoluminescence decay kinetics of alkali halides

Photoluminescence decay kinetics of alkali halide crystals activated with thalium, indium, tin and europium is investigated. Excitation arises both in short-wave and long-wave bands of impurity absorption. It is determined that decay accurs in two stages that is there existc hyperbolic stage alongside with wellknown exponential one. Spectra of activator luminescence at ifferent moment of its decay undergo no changes. Contribution of an exponential stage is determined by activator concentration and by the fact whether excitation occurs in long- or short-wave band of absorption. Exponential component is minimal one in crystals with low impurity content. The results are explained on the basis of the model suggested by the authors earlier for formation of excimerlike bond between the space-separated defects during excitation. Consideration of luminescence decay kinetics made from the point of view of this model allows to realize Becquerel empirical law of decay