Formation and decay of nonbridging oxygen hole centers in SiO2 glasses induced by F-2 laser irradiation: In situ observation using a pump and probe technique

Formation and decay of nonbridging oxygen hole centers (NBOHC, an oxygen da ngling bond) in SiO2 glasses by F-2 excimer laser (7.9 eV) irradiation were in situ analyzed by monitoring 1.9 eV photoluminescence of NBOHC using a p ump and probe technique. In wet SiO2, the SiO-H bond was efficiently photol yzed by F-2 laser photons to form NBOHC with a quantum yield of similar to0 .2. However, the recombination with dissociated hydrogenous species suppres sed the buildup of NBOHC. In dry SiO2, in contrast, NBOHC formation by diss ociation of strained Si-O-Si bonds was inefficient but NBOHC accumulated wi th the number of F-2 pulses due to a negligibly slow reverse recombination reaction. (C) 2001 American Institute of Physics.