Anomalous drift of resonant particles in a buffer medium under pressure of light

We study theoretically the drift of resonant particles in a buffer medium when a traveling light wave impinges on the medium, with allowance for the velocity dependence of the transport collision rate. When the pressure of light dominates over the light-induced drift (low pressure of the buffer gas or the drift of conduction electrons in semiconductors), we discover a new sudden transformation of the spectral dependence of the drift velocity of the resonant particles: Instead of the ordinary bell-shaped function representing the velocity spectrum we have a double-humped curve with deep dip at the center of the absorption line. We show that the largest transformation of the drift velocity spectrum occurs in the atmosphere of a heavy buffer gas in the case of Coulomb interaction between the resonant and buffer particles. The transformation effect is caused by the variation of the transport rate of the collisions of the resonant and buffer particles due to the recoil effect in the absorption of radiation. Zh. éksp. Teor. Fiz. 112, 856–868 (September 1997)