RHODE ISLAND UNIV KINGSTON DEPT OF ELECTRICAL ENGINEERING
The authors report measurements of the absorption coefficients of CaF2, SrF2 and BaF2 in the frequency range approximately 700 to approximately 1600 per cm, at temperatures ranging from 300 to 800K. The frequency dependence is found to be nearly exponential-like in the temperature range investigated, in agreement with existing multiphonon theories. A detailed analysis of the measured temperature dependence, using the theories of Bendow, and of Namjoshi and Mitra, shows that the observed behavior conforms overall to that predicted for intrinsic multiphonon processes. The role of the temperature dependence of the phonon spectrum in suppressing the temperature dependence of the multiphonon absorption is also investigated.
Pub. in Proceedings of Conference on Optical Properties of Highly Transparent Solids, 1975.