摘要
F_(2) centers in colored undoped and doped NaF crystals can be converted nearly completely into F_(2)^(+) centers with the high density of more than 10^(17)cm^(-3) by irradiating the crystals with a 505nm laser at room temperature.A process of conversion from F_(2)^(+) to (F_(2)^(+))^(*) centers in the NaF crystals doped with divalent metal ions such as Mn^(++),Mg^(++) and Ni^(++) after the 505nm laser irradiation was observed in our experiments.
