Heat flow in a gas exposed to radiation in resonance with a vibrational–rotational Doppler-broadened transition

It is shown that in a molecular gas exposed to a resonant wave both a heat flow and a temperature gradient are observed as a result of drift and transformation into heat of the rotational energy of molecules interacting with the field. As a result, a change in density comparable with that observed experimentally is found. An experiment is proposed to determine the contributions of the heat flow and optically induced drift.