Symmetry Properties of theV1Center

The symmetry of the $V_1$ center was studied using a technique of bleaching with polarized light. The $V_1$ band in KCl and KBr produced by x-rays and 2-Mev electron bombardment was examined. In addition, the effect of bleaching with polarized light on the phosphorescent emission of KCl was observed. It is concluded that the center responsible for the $V_1$ absorption band in KCl and KBr has cubic symmetry insofar as its optical absorption is concerned. The phosphorescent emission of KCl became anisotropic under polarized bleaching light, indicating the presence of a center of noncubic symmetry. This second center has a [011] axis of symmetry.