Effect of Pre-Irradiation Annealing and Laser Modification on the Formation of Radiation-Induced Surface Color Centers in Lithium Fluoride

It is shown that surface color centers of the same type are formed in the surface layer and in regions with damaged crystal structure inside crystalline lithium fluoride after gamma-irradiation. Results are presented from a study of the effect of pre-irradiation annealing on the efficiency with which surface centers are formed in lithium fluoride nanocrystals. Raising the temperature for pre-irradiation annealing from room temperature to 250A degrees C leads to a substantial reduction in the efficiency with which these centers are created. Surface color centers are not detected after gamma-irradiation for pre-irradiation annealing temperatures of 300A degrees C and above. Adsorption of atmospheric gases on the crystal surface cannot be regarded as a necessary condition for the formation of radiation-induced surface centers.