We have experimentally investigated the selective reflection of the $P-D$ transition in a high-density rubidium vapor and shown it to be sensitive to the exact spatial distribution of $P$-state atoms near the dielectric-vapor interface. This distribution results from the radiative and nonradiative transport of excitation and from wall-quenching collisions of excited-state atoms and is highly inhomogeneous. Selective reflection thus acts as a probe of the spatial dispersion in the vapor. The resulting spectra have been analyzed to show that the broadening due to $S-D$ collisions contributes considerably to the self-broadened linewidth of the $P-D$ transition.

• Received 17 November 1997

DOI:https://doi.org/10.1103/PhysRevA.58.4473