OH−ions in Oxide Crystals

This article reviews the spectroscopic properties of hydrogen bound to a large variety of synthetic compounds like simple oxides, perovskites, the LiNbO3 family, KTP, sillenites, eulytites, borates, garnets, spinels and some others. In almost all compounds the OH stretch mode is found in the range 3200-3700 cm−1, with isotope replica of deuterium (2350-2750 cm−1) and a few examples of tritium (2050-2250 cm−1). The fundamental vibration, the isotope replica and the corresponding overtones are described with an anharmonic oscillator model. A nonlinear relation between the anharmonicity and the harmonic frequency is found and interpreted using recent second order perturbation calculations. An often pronounced temperature dependence of the stretch mode and phonon coupling is discussed. Data for the stretching vibration influenced by additional weak or strong doping are presented. Atomistic defect models are described and tested by means of light polarization, external perturbations like pressure and electric field, and Raman scattering analyzed with the behavior-type method. The last section briefly reviews applications profiting from doping with hydrogen and its easy detection by means of the OH stretch mode.