Infrared spectra of hydrogen isotopes inα-Al2O3

Infrared absorption of O${\mathrm{H}}^{-}$, O${\mathrm{D}}^{-}$, and O${\mathrm{T}}^{-}$ in $\alpha$-${\mathrm{Al}}_2$ ${\mathrm{O}}_3$ at 77 K occurs at energies of 3282, 2439, and 2069 ${\mathrm{cm}}^{-1\mathrm{}}$, respectively. A small band at 3266 ${\mathrm{cm}}^{-1\mathrm{}}$ disappeared after high-temperature treatment of the crystal and was attributed to an O${\mathrm{H}}^{-}$ ion which is perturbed by an unidentified defect. Calculations of the electrostatic potential combined with measurements of the polarization of the absorbed light indicated that the O${\mathrm{H}}^{-}$ ion lies in the basal plane of the crystal. No evidence was found from measurements of the EPR spectrum of a $\gamma$-irradiated crystal for the presence of $V_{\mathrm{OH}}^{-}$ centers in $\alpha$-${\mathrm{Al}}_2$ ${\mathrm{O}}_3$.