Fourier ir and raman spectroscopy of the OH stretch modes in KTaO₃

Abstract

Undoped single crystals of KTaO₃ grown in our crystal growth laboratory show only one isotropic absorption line which is due to an OH stretch mode. Conflicting results with more than one mode have been reported so far. A well resolvable splitting is observed for an electric field applied perpendicular to the light propagation. From the overtone and the corresponding frequencies of the deuteron isotope, the spectroscopic parameters for an anharmonic oscillator are deduced. Right angle Raman scattering yield the Raman tensor of the dipole ensemble and point to an almost undisturbed charge distribution, when compared with the free OH molecule.