Interaction of Exciton with Electron Trapping Centers in Alkali Halide Crystals

1. F and U Centers in KCl and KBr Crystals

Abstract

The quantum efficiency for the bleaching of F centers in the KCl crystal with incident ultra violet lights in the region of the fundamental absorption band was obtained to have five times larger value than that with the visible light in F-absorption region. With the estimation of the absorption coefficient of the crystal at the fundamental absorption tail, it is infered that one exciton can bleach at least six F centers. From the similar experiments to measure the quantum efficiency for the process of U→F transformation using monochromatic lights, it is concluded that one exciton is able to transform about three U centers. Dependence of the quantum efficiency on the wavelength of exciting light was determined in the KBr crystal.