Oblique Polaritons in Uniaxial Crystals: Application to LiIO3

Abstract
In Raman scattering involving polaritons propagating at arbitrary oblique angles with respect to the crystallographic axes, the selection rules derived for polaritons propagating along the crystal axes are no longer obeyed. We present the analysis of oblique polaritons which account for their frequency dispersion as a function of both the magnitude and the direction of the wave vector k. Application of this theory to the experimental results obtained for LiIO3 easily clarifies the appearance of "new" lines in the polariton region.