Splitting of atomic beams by Raman transitions in continous light waves

A new scheme for a coherent splitting of atomic beams is presented. The scheme is based on Raman transitions between two stable sublevels of an atom induced by a bichromatic standing light wave and a superimposed traveling light wave. The main advantage of the scheme is that the population of the excited state of the atom can be very small. Therefore the probability of interrupting the coherent de Broglie wave splitting by spontaneously emitted photons is very low. These properties of the beam splitter allow to apply it for all alkali atoms with strong transitions including the case of very slow atoms. We show that the momentum splitting can be as large as few hundred times the photon momentum.