The behavior of interstitial oxygen atoms induced by F₂ laser irradiation of oxygen-rich glassy SiO₂

Interstitial oxygen atoms in glassy silicon dioxide were created by photolysis of pre-existing interstitial oxygen molecules O₂ with a fluorine excimer laser (7.9 eV). The concentration of atomic oxygen interstitials was indirectly monitored by the disappearance and subsequent recovery of interstitial molecules which were monitored by their 1272 nm photoluminescence band. Most of the oxygen interstitials (>95%) are immobile at room temperature. The onset of their mobility occurs between 200 and 400 °C where around 95% of them recombine to form O₂ molecules. The high stability of interstitial oxygen atoms is consistent with the theoretical prediction that they are incorporated into silica structure in a form of peroxy linkages (POLs) Si-O-O-Si. The radiation-induced optical absorption band around 7.1 eV is tentatively assigned to POLs.