We report an experimental investigation of the Cs ${\mathit{D}}_2$ line-shape changes due to laser-induced optical pumping and collisions in a buffer gas. A model dealing with the population of the ground-state hyperfine levels, the pressure broadening in the presence of Ne, and the diffusion of the atoms outside the laser beam describes well the complex line shapes.

• Received 29 December 1992

DOI:https://doi.org/10.1103/PhysRevA.48.3820