Model of first-stageF-center production in alkali halides containing divalent cation impurities

Abstract

A system of equations, describing the formation of $F$ centers and their complements in irradiated alkali halides doped with divalent impurities, has been developed. These incorporate the stabilization of $H$ centers and di-interstitial halogen defects at impurity-vacancy dipoles or aggregates of such dipoles, as well as radiation-induced interstitial detrapping mechanisms. Numerical and approximate analytical solutions of the equations reproduce the dynamic, temperature-dependent features of $F$-center growth found in experimental studies. They provide a new explanation of the experimentally observed relations between the growth of defects and the divalent-cation-impurity concentration; i.e., the square-root relation between first-stage $F$ centers and such impurities, and the relation between the saturation concentration of $H_D$ centers and these impurities.