Sub-Doppler manifestation of the magneto-optical radiation force.

We consider a novel manifestation of the magneto-optical radiation force for an optical transition with a ground-state magnetic substructure. The force originates from optical Zeeman-pumping in close relation to polarization cooling with linearly polarized light and, at low optical saturation, exhibits sub-Doppler dependnece on the atomic velocity. We show that, in an inhomogeneous magnetic field, the radiation force an be used for the magneto-optical trapping of ultracold atoms