Excimer-laser-induced emission bands in fused quartz

The characteristics of KrF (5.0 eV) and ArF (6.4 eV) -excimer-laser-induced luminescence in type-I ([OH]<5 ppm) and type-II ([OH]=120 ppm) fused quartz were investigated. These two types of fused quartz have an absorption band near 5 eV, called the ${\mathit{B}}_2$ band. Comparing the absorption and the emission bands under excitation by these excimer lasers, we found that the ${\mathit{B}}_2$ bands in these types of fused quartz derived from different origins: In type-II fused quartz, the ${\mathit{B}}_2$ band is the ${\mathit{B}}_2$ β band caused by silicon lone-pair center (=Si:), which can be annealed out in air. The ${\mathit{B}}_2$ band in type-I silica consisted of two types of ${\mathit{B}}_2$ bands: the main component of this band is the ${\mathit{B}}_2$ α band caused by an oxygen-deficient center (≡Si...Si≡) and the other component is a small amount of the ${\mathit{B}}_2$ β band. We proposed a model in which these defects are located on the grain boundary, which is a trace of the contact between silica and silica particles.