Light-induced drift in a gas mixture with spectral structure formed by radiative transfer

Abstract

It has been suggested that white light-induced drift might be a mechanism for the separation of species in chemically peculiar stars. Light-induced drift velocities are calculated as a function of optical depth for two species of two level atoms in a gas mixture. Fraunhofer spectral lines form by radiative transfer as the light escapes from the optically-thick environment. Both species are assumed to be identical except for their resonant frequencies, which are separated by a small frequency displacement on the order of the Doppler width. Complete frequency redistribution is assumed. It is found that outward and inward propagating light both contribute to the light-induced drift. The outward contribution dominates near the edge of the vapor. Calculated drift velocities are ∼ 1 m/sec at temperatures of 6000 K.