Measurement of the Effect of Resonant Light Pressure on the Dispersion Curve of a Gas of Two-Level Atoms

Abstract

The study of resonant light forces on the motion of free atoms is of strong current interest. So far, most of the experiments on light forces have been performed on atomic beams: It has been shown that atoms in a beam can be strongly deflected, decelerated, and even trapped by laser light. Although, quite obviously, resonant light forces can also act on the atoms in a gas /1/, very few experimental work has been performed on light pressure effects in gases; here the total modification of the velocity distribution that can be achieved by resonant light pressure under normal experimental conditions seems to be insignificantly small. Recent investigations, however, showed that even very small light-pressure-induced modifications of the atomic velocity distribution can have substantial effects on the optical response of a gas to laser light; here the effect of light pressure shows up in the transmitted light and is manifested in modifications of absorption and dispersion profiles.