Annealing temperature effect on the absorption spectra of γ-irradiated LiF crystals

Isochronous (1 day) annealings of lithium fluoride monocrystals gamma-irradiated at 77 K ensuring consequent decay of Vk centres (195 K), the motion of anionic vacancies (255 K) and decay of F2+ (295 K) centres have shown a decrease as a result of each annealing of absorption indices for the bands with the maxima of 245 and 340 nm with approximately equal ratio. As a result the intensity of centre band decreased by a factor of 2, and bands with the maximum of 340 nm - by a factor of 5. Besides, after annealing at 195 K the band with the maximum of 750 nm has disappeared, and a band with the maximum of approximately 600 nm has appeared, the intensity of which decreased with consequent annealings; annealing at 255 K resulted in the appearance of a band with the maximum of about 635 nm (F2+ centres), which disappeared after annealing at 295 K