Inelastic collisions between selectively excited rubidium atoms and ground-state rubidium atoms

Inelastic-collision processes in fine-structure-changing collisions have been studied by selective stepwise excitation and observation of the resulting fluorescence. Hereby, the effect of ground-state rubidium atoms colliding with excited-state rubidium atoms was investigated. The ground-state density was changed by three orders of magnitude by performing the measurements over the temperature range of 75 to 200 °C. The cross section for fine-structure-changing collisions [i.e., $\mathrm{Rb}\left(6^2{D}_{\frac{5}{2}}\right)+\mathrm{Rb}\left(5^2{S}_{\frac{1}{2}}\right)\to \mathrm{Rb}\left(6^2{D}_{\frac{3}{2}}\right)+\mathrm{Rb}\left(5^2{S}_{\frac{1}{2}}\right)$] is ${\sigma }_{\mathrm{fs}}=(1.0\mathrm{}\pm 0.6)\times {10}^{-13\mathrm{}}$ ${\mathrm{cm}}^2$. The cross sections for transfer out of the fine-structure doublet [i.e., $\mathrm{Rb}\left(6^{2}D\right)+\mathrm{Rb}\left(5^2{S}_{\frac{1}{2}}\right)\to \mathrm{states}\mathrm{other}\mathrm{than}\mathrm{Rb}\left(6^{2}D\right)$] is ${\sigma }_{\mathrm{tr}}=(3.8\mathrm{}\pm 0.6)\times {10}^{-13\mathrm{}}$ ${\mathrm{cm}}^2$. It is demonstrated that for the intermediate excited rubidium states, both the fine-structure-changing and transfer cross sections are of the order of the geometrical cross section of the excited rubidium states.