Temperature Dependence of the Absorption Coefficient of Alkali Halides in the Multiphonon Regime

Abstract
The theory of infrared absorption by an array of independent, anharmonic oscillators is discussed. When the oscillator potential is the Morse potential, the theory provides an excellent description of the temperature dependence of the absorption coefficient at 10.6 μm in NaCl and NaF reported by Harrington and Hass.