Temperature Dependence of Multiphonon Absorption

Abstract
The temperature dependence of multiphonon absorption in NaF, NaCl, and KCl was studied from room temperature to near the melting point at a wavelength of 10.6 μm. A large discrepancy was noted between the experimental results and those predicted using the usual expressions based upon temperature-dependent Bose-Einstein population factors and temperature-independent transition matrix elements.