An empirical model of optical susceptibilities of crystals II. Elasto-optical effect in alkali halides

Abstract

The elasto-optic coefficients p^a re described in terms of the bond polarizability ß and in terms of /, which measures the relative change of ß caused by a relative change of the bond length. It is shown that two types of ß do exist, a longitudinal and a transverse one. The values of ß as determined from the p^h ave been related to the bond lengths and to the ionic radii. Only few quantities are needed to describe the elasto-optic coefficients and the optical susceptibilities in all alkali halides.

Calculations of hyper-Raman tensor components of alkali halides

“…The ionic radii correspond to the minimum of electron density between cation and anion as determined in x-ray scattering experiments. The values of β L and f L l have been derived from interionic part of the linear optical susceptibility from elasto-optic data by Weber (1986). The dependence (∂f i /∂R) has been calculated previously in terms of the Phillips-Van Vechten theory and applied to evaluate the volume dependence of the Szigeti effective charge in alkali halides (Kucharczyk 1991).…”