Color centers in ruby crystals with varying activator concentrations

A study is made of the recharging of color centers in ruby single crystals due to UV irradiation and thermal activation. It is shown that the color level and the mechanisms of interaction between color centers are a function of the mass concentration of the activator, Cr(3+). UV irradiation leads to the transfer of holes from anion vacancies to the valence zone and localization at the hole centers: V-centers and Cr(3+) ions. For Cr(3+) concentrations above 0.04 percent, activator ion complexes are a determining factor in the formation of color centers. Models of color center recharging are examined.