Coherence effects in light-induced drift

Abstract

The occurrence of black resonances in light-induced drift in a Na-Xe mixture is demonstrated experimentally. On the D 1 a strong effect on the drift velocity is observed, whereas on the D 2 line the effect is less pronounced. This difference is explained in terms of excited state hyperfine structure. The effect is described with a four level rate-equation model, in which the influence of the ground-state coherence has been included. A sign reversal of the light-induced drift velocity at the black resonance is predicted for small laser bandwidths.