High Resolution FT-IR Spectroscopy of OH− Ion Perturbed by Sr2+ in KCl

High resolution (0.04cm−1) FT-IR absorption spectroscopy was applied in the range 9-300 K to study vibrational modes of OH− in KCl: Sr2+ mixture. The lines (very narrow at 9 K) in the range 3500–3650 cm−1 were attributed to the stretching of OH− embedded in Sr2+-complexes. The spectra (fundamentals, overtones, and isotopic replicas) were analysed in by means of the Morse anharmonic oscillator model, the parameters of which were evaluated and discussed. A single phonon coupling model, applied to the temperature-dependence of the line position, provided the frequencies of the coupled phonons.