ArF-excimer-laser-induced emission and absorption bands in fused silica synthesized in reducing conditions

ArF-excimer-laser-induced luminescence and absorption bands in type-III fused silica synthesized in a reducing condition were investigated. The fused silica shows 4.4-eV emission and 5.8-eV absorption bands ascribed to be the E’ center (?Si⋅). By annealing in various atmospheres, the creation of these bands is suppressed: The order of the suppression effect is as He≃${\mathit{O}}_2$>air>${\mathrm{N}}_2$. The 5.8-eV band decays after cessation of the irradiation. To describe these phenomena we proposed a model that the precursor of these bands is the ?Si-H H-O-Si? structure: By irradiating with an ArF-excimer-laser beam, the E’ centers are created as ?Si-H H-O-Si? →?Si⋅ H-O-Si?+H, and the E’ center decays after cessation of the irradiation by recombining with the hydrogen. By annealing, the structures are changed by the reaction ?Si-H H-O-Si?→?S-O-Si?+${\mathrm{H}}_2$. This reaction is enhanced by removing the hydrogen molecules by annealing in helium and oxygen.