Laser-induced-fluorescence detection of collisional excitation transfer in atomic rubidium vapor during collisions with noble-gas and rubidium atoms

The 8 ${}_{}{}^2{}_{}{}^{}S$ state of rubidium is selectively populated by stepwise excitation using light from a rubidium lamp and a tunable dye laser. Excitation transfer from the 8 ${}_{}{}^2{}_{}{}^{}S$ to the 6 ${}_{}{}^2{}_{}{}^{}D$ state is studied in a glass cell containing rubidium vapor and noble-gas atoms at different pressures and ground-state rubidium atoms as perturbers. The thermally averaged cross sections for excitation transfer (in units of ${10}^{\mathrm{-}15}$ ${\mathrm{cm}}^2$) are 0.13±0.05, 3.0±1.2, 2.2±0.9, 1.7±0.7, and 4.3±2.6 for the noble gases He, Ne, Ar, Kr, and Xe, respectively, and (6.7±3.0)×${10}^{\mathrm{-}13}$ ${\mathrm{cm}}^2$ for rubidium atoms. The results show that the excitation-transfer cross sections for intermediately excited states cannot be accurately scaled from simple models.