Accumulation features of radiation-induced hydrogen defects in LiF

Infrared absorption and electron paramagnetic resonance spectra have been investigated for LiF:OH crystals irradiated in a nuclear reactor at low and normal reactor temperatures. The influence of irradiation temperature on accumulation of interstitial hydrogen ions Hi- (U1-centers) was studied. It was observed that these centers were predominantly accumulated under the low-temperature irradiation. The maximum frequency of local vibrations of Hi- ions in LiF depended on the irradiation dose. The shift of vibration frequency of U1-centers to low energy with the increase in the irradiation dose was studied and analyzed. Negative hydrogen ions [H−] in anionic sites (U-centers) were registered in irradiated LiF:OH crystals without their preliminary thermal treatment after the neutron irradiation both at reactor and low temperatures. Accumulation of hydrogen atoms (U2-centers) in LiF for different irradiation fluxes was studied by the thermal treatment. After the irradiation of LiF:OH at 20 K the H0 atoms were observed without annealing of the crystal.