PHASE-DEPENDENT RADIATION FORCE ON MULTILEVEL ATOMS

We investigate theoretically the behavior of multilevel atoms in a las er light field formed by a pair of counterpropagating, linearly polari zed laser beams in the presence of a longitudinal magnetic field. The light force is derived under the condition of an arbitrary angle betwe en the two polarization planes. We show that, for parallel polarizatio n, phenomena that are characteristic for two-level atoms (like Doppler on resonances and a force-inversion for low velocities) prevail. For o rthogonal polarization and an angular momentum J(g) = 1/2 of the groun d state, a sub-Doppler cooling force occurs even in the limit of high saturation. For all other polarization angles, we find a stimulated re distributive force, which can be completely rectified depending on las er frequency, magnetic field strength, and saturation.