Infrared absorption by free polarons

Expressions are obtained for the coefficient of absorption of a weak electromagnetic wave by free carriers in polar semiconductors with interaction of polarons with acoustic and optical phonons. The appearance in the absorption coefficient of Feynman variational parameters leads, in general, to a change in the frequency dependence. The results are applicable for the frequency range (), where () is the mean reciprocal relaxation time.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 76–80, July, 1980.