Effect of uniaxial stress on dynamics of electronic excitations in alkali halides

The effect of uniaxial stress supplied at various temperatures along the (100) crystal axis on the different stages of electronic excitation relaxation has been studied for several alkali halides. An increase in the intrinsic/extrinsic emission intensity ratio has been found and explained by the stress-induced increase of the self-trapping efficiency of electronic excitations and the corresponding decrease of their migration length, as well as by the stress-induced reduction of the efficiency of the non-radiative decay of electronic excitations. The increase of energy barriers between various self-trapped exciton configurations has been detected. The origin of the E-x emission in KI and RbI crystals as well as of the fast ultraviolet emissions of localized excitons in CsI is discussed. (C) 1998 Elsevier Science B.V. All rights reserved.