Anomalous transmission in atom optics

Anomalous transmission for X-rays in crystals as discovered by Borrmann can also be observed for atoms interacting with a standing light wave on resonance. It may be interpreted as a manifestation of a grey state. We describe phenomena based on anomalous transmission for various regimes of the atom-light interaction and elucidate these by numerical calculations for argon and calcium. The grey state in anomalous transmission is linked to the dark state in velocity selective coherent population trapping in atomic threelevel A systems.