Formation and decay of nonbridging oxygen hole centers in SiO2 glasses induced by F2 laser irradiation:: In situ observation using a pump and probe technique

Formation and decay of nonbridging oxygen hole centers (NBOHC, an oxygen dangling 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 pump and probe technique. In wet SiO2, the SiO-H bond was efficiently photolyzed by F-2 laser photons to form NBOHC with a quantum yield of similar to0.2. However, the recombination with dissociated hydrogenous species suppressed the buildup of NBOHC. In dry SiO2, in contrast, NBOHC formation by dissociation of strained Si-O-Si bonds was inefficient but NBOHC accumulated with the number of F-2 pulses due to a negligibly slow reverse recombination reaction. (C) 2001 American Institute of Physics.