Effects of synthesis conditions on existence and nonexistence of the ArF excimer laser and x-ray inducedB2α band in type-III fused silicas

ArF excimer laser and x-ray induced absorption bands in type-III fused silica synthesized under reducing (sample DR) and oxidizing (sample DO) conditions were investigated. Under ArF excimer laser and x-ray irradiation, an absorption band at 5.0 eV called the ${\mathit{B}}_2$α band and ascribed to an unrelaxed oxygen-deficient center was observed only in the sample DR and was not observed in the sample DO. Emission bands at 4.4 and 2.7 eV induced by exciting the ${\mathit{B}}_2$α band only appeared in the sample DR. The creation mechanism of the ${\mathit{B}}_2$α band in the sample DR and the reason for the nonexistence of the ${\mathit{B}}_2$α band in the sample DO were discussed.