Thermo- and photo-stimulated processes were studied in H-containing -phase samples which were excited by ultra-violet light. It was found that ultra-violet excitation of the F absorption band at 90K resulted in ionization of the F-centers and the capture of released electrons at defects; thus producing an anisotropic absorption band at 4.2eV and a predominant thermoluminescence peak at 260K. This peak was accompanied by complete bleaching of the 4.2eV absorption band. Light stimulation in the region of the 4.2eV band caused the 260K thermoluminescence peak to disappear, and the released electrons recombined with F-centers. The effect of high-temperature heat treatment upon the formation of 4.2eV centers, and the observed dichroism characteristics, led to the conclusion that the corresponding complex defect contained H and could involve a vacancy pair.

M.Springis, P.Kulis, I.Tale: Radiation Effects and Defects in Solids, 1995, 134, 481-3