Mechanism for Coloration of Alkali Halides at Low Temperatures

Abstract

A mechanism for low-temperature coloration of alkali halides is proposed in which double ionization of a halide ion or single ionization of two adjacent halide ions leads to the formation of an uncharged halogen molecule which occupies two adjacent halide ion sites. If the molecule is localized at one of these sites by the jump of a nearby halide ion into the other site, a vacancy and interstitial are formed. Capture of an electron by each of these imperfections leads to the production of the $F$ center and $H$ center.