On the velocity redistribution of atoms interacting with a light beam

Jan Fiutak, S Kryszewski, S. Zielinska

S Zielinska

A simple method which allows one to study the influence of all relaxation processes and the pumping rate on the velocity distribution of the two-level atom populations is reviewed. In particular, the author presents a treatment that consistently includes the effects of phase and velocity relaxation on the atomic coherences. This method is applied to describe the drift of absorbing atoms-the effect which is also named light-induced gas diffusion. The results of numerical calculations for the drift velocity are presented and the role of the atomic coherences in the description of this phenomenon is pointed out. The dependence of the drift velocity on various parameters is discussed and the best experimental conditions for observing this effect are suggested.

Yu. G. Abashev, Gennady F. Voronin, R. A. Valitov

Soo Chang, Taeg Yong Kwon, Ho Seong Lee +1 more

It is shown that dipole interaction of multilevel atoms having three or more ground-state sublevels with counterpropagating circular polarized laser waves is strongly influenced by ground-state coherence produced by two-photon processes. In the simplest case of a (3+5)-level atom the ground-state coherence is shown to be responsible for constructive atomic interference that enhances upper atomic populations at small velocities. Ground-state coherence is also responsible for the coherent redistribution of the ground-state atomic populations at small velocities. It is found that a two-photon coherent redistribution of atomic populations enhances considerably the radiation force at small velocities and accordingly the friction produced by the radiation force.

C.G. Aminoff

Optical pumping performed with a quasi monochromatic laser beam in an atomic gas introduces a redistribution of Zeeman populations selectively in a single velocity class. In the limit of low pumping intensity the rate theory is valid for a description of velocity-selective optical pumping (V.S.O.P.). Well-defined atomic observables (population, orientation, alignment) and their velocity-correlated collisional relaxation can be studied. Also, a modified scheme for the detection of second order effects of optical pumping allows one to observe light shift induced signals. In particular, V.S.O.P. and its combination with modulated pumping, magnetic depolarization (level crossing), and magnetic resonance techniques provide information about the atomic collision characteristics such as collision rates and kernels for velocity-changing collisions.