SubstitutionalH−-ion vibrations in the alkaline-earth oxides reduced at high temperatures

The infrared absorption spectra of MgO, CaO, and SrO, crystals containing high concentrations of hydrogen are studied. Samples reduced at high temperatures and high pressures of the alkaline-earth vapor exhibit sharp absorption lines that can be attributed to the fundamental vibrations of substitutional ${\mathrm{H}}^{-}$ ions. In MgO:${\mathrm{H}}^{-}$ a first-harmonic line is also observed. A comparison is made with results for ${\mathrm{H}}^{-}$ ions in the alkali halides.