Color Centers in MgF2

Abstract

The effects of radiation temperature and intensity on the colorability of Mg${\mathrm{F}}_2$ single crystals obtained from various commercial sources were investigated. The results show that the radiation-damage process in Mg${\mathrm{F}}_2$ is photochemical in nature and strikingly similar to that in the alkali halides. In the past it has been proposed that long-range focusing events are, in part, responsible for the photochemical coloration of the alkali halides. However, in Mg${\mathrm{F}}_2$ there are no obvious long-range focusing directions, and the data suggest that such a process is not necessary for the production of photochemical damage. The radiation equilibrium observed to prevail between $F$ and $M$ centers in KCl is also evident in Mg${\mathrm{F}}_2$, and this effect was used to propose that absorption bands at 370 and 400 nm are due to $M$ centers.