Infrared photoluminescence of preexisting or irradiation-induced interstitial oxygen molecules in glassySiO2and α-quartz

A sensitive technique for detecting interstitial ${\mathrm{O}}_2$ molecules in ${\mathrm{SiO}}_2$ is demonstrated by measuring their infrared $\overrightarrow{a}X$ luminescence at 1272.2 nm under a Ti-sapphire laser excitation into the ${\mathrm{O}}_2\overrightarrow{X}b$ absorption band at 765 nm. Contrary to the case of ${\mathrm{O}}_2$ trapped in inert gas matrices, the visible emission of ${\mathrm{O}}_2$ corresponding to the direct $\overrightarrow{b}X$ transition is not found. Examination of different neutron- and gamma-irradiated glassy ${\mathrm{SiO}}_2$ and α-quartz samples reveals radiation-induced interstitial oxygen molecules in concentrations between ${10}^{14}$ and ${10}^{16}{\mathrm{m}\mathrm{o}\mathrm{l}\mathrm{e}\mathrm{c}\mathrm{u}\mathrm{l}\mathrm{e}\mathrm{s}/\mathrm{c}\mathrm{m}}^3.$ The radiolytic ${\mathrm{O}}_2$ molecules in α-quartz and glassy ${\mathrm{SiO}}_2$ experience different structural environments.