Correlation between the green photoluminescence band and the peroxy radical in γ-irradiated silica glass

We studied the origin of a green photoluminescence (PL) in silica glass at about 2.25 eV using electron spin resonance. The 2.25 eV PL band (lifetime: similar to 300 ns, full width at half maximum: similar to 0.2 eV) appears strong in gamma-irradiated high-oxygen content silica glass suggesting that this PL is associated with a large surplus of oxygen states in silica glass. We investigated the correlation between the 2.25 eV PL band and the peroxy radical by the isochronal annealing method. Peroxy radicals are formed by the O(3)drop Si-O-O . bond (.: unpaired electron) and the small "peroxy radical" (SPR) bond in silica glass. Based on the annealing characteristics of the 2.25 eV PL band and the peroxy radical, we suggest that the PL band is associated with a surplus of oxygen defects formed by the SPR rather than the O(3)drop Si-O-O . bond. (C) 2000 American Institute of Physics. [S0021-8979(00)01112-9].