Atomic lattice structures in two-dimensional momentum space

In sub-Doppler laser cooling, the application of an additional homogeneous magnetic field gives rise to velocity selective resonances and laser cooling to nonzero velocities. We present a systematic investigation of the resulting structures in two-dimensional momentum space in an atomic beam experiment. The rms width of the resonances is close to one recoil momentum. The analysis of these structures in terms of a resonance condition shows good quantitative agreement with experimental results.