Interstitial O3 molecules were identified in 7.9eV photon-irradiated silica. Their optical absorption band at 4.8eV almost coincided with the 4.8eV band of non-bridging O hole centres. The O3-related band was distinguished by a smaller half-width (0.84 rather than 1.05eV), by a susceptibility to ultra-violet bleaching, by a lack of correlation with the 1.9eV luminescence band, and by an increase in the singlet O2 luminescence band at 0.974eV during photo-bleaching. This identification ended a long controversy concerning the nature of optical bands in silica, and offered a tool for the study of the mobility of atomic O in SiO2.

Oxygen-Related Intrinsic Defects in Glassy SiO2: Interstitial Ozone Molecules. L.Skuja, M.Hirano, H.Hosono: Physical Review Letters, 2000, 84[2], 302-5