CHARACTERISTICS OF ARF-EXCIMER-LASER-INDUCED 1.9-EV EMISSION BANDS IN TYPE-III AND SOOT-REMELTED SILICAS

Characteristics of the ArF-laser-induced emission band at 1.9 eV in type-III fused silica and soot-remelted silica were investigated. After annealing in ambient helium, the creation of the 1.9-eV band was enhanced in type-III fused silica, but suppressed in soot-remelted silica. We propose a model to describe the annealing mechanism in the soot-remelted silica and compare it to the annealing mechanism previously proposed in type-III silica. The precursor of the 1.9-eV band is O2 molecules trapped in the glass network. In the soot-remelted silica, the O2 molecules are localized in the ''grain boundary'' which is the trace of the fusion of the silica particles. These O2 molecules will diffuse into the glass to disperse homogeneously at high temperature, and the mean separation of the nearest-neighbor O2 molecules will increase to reduce the intensity of the 1.9-eV band.