Three dimensional polarization dependence of OH bands absorption in potassium niobate crystals

Absorption band countered on wave numbers 3504 and 6843 cm^-1 have been observed in potassium niobate crystals. These absorption bands correspond to the transition energies of O-H stretching vibration, from the ground state to the first excited state and to the second excited state, respectively. Absorption bands around 3992 and 4476 cm^-1 are attributed to the combination of O-H vibration plus libration. The integrated absorption intensities around 3504, 3992, and 4476 cm^-1 are three dimensional polarization dependent which indicates the motion properties of hydrogen ions in the lattice.