7D322−7D522excitation transfer in rubidium induced in collisions with ground-state Rb and noble-gas atoms

Cross sections for $7{}_{}{}^2{}_{}{}^{}D_{\frac{3}{2}}^{}{}_{}{}^{}\leftrightarrow 7{}_{}{}^2{}_{}{}^{}D_{\frac{5}{2}}^{}{}_{}{}^{}$ transfer in Rb, induced in collisions with He, Ne, Ar, and with ground-state Rb atoms, have been determined using methods of atomic fluorescence. Rb vapor, pure or mixed with a noble gas, was irradiated in a glass fluorescence cell with pulses of 660-nm radiation from a ${\mathrm{N}}_2$-laser-pumped dye laser, populating one of the ${}_{}{}^2{}_{}{}^{}D$ states by two-photon absorption. The resulting fluorescence included a direct component emitted in the decay of the optically excited state and a sensitized component arising from the collisionally populated state. Relative intensities of the components yielded the cross sections for $7{}_{}{}^2{}_{}{}^{}D$ mixing: $Q({}_{}{}^2{}_{}{}^{}D_{\frac{3}{2}}^{}{}_{}{}^{}\to {}_{}{}^2{}_{}{}^{}D_{\frac{5}{2}}^{}{}_{}{}^{})=8.8,6.5,10.4, \mathrm{and} 30$; $Q({}_{}{}^2{}_{}{}^{}D_{\frac{3}{2}}^{}{}_{}{}^{}\leftarrow {}_{}{}^2{}_{}{}^{}D_{\frac{5}{2}}^{}{}_{}{}^{})=5.8,4.0,6.9, \mathrm{and} 18$, in units of ${10}^{-14\mathrm{}}$ ${\mathrm{cm}}^2$ for He, Ne, Ar, and Rb, respectively. Cross sections for the effective quenching of the ${}_{}{}^2{}_{}{}^{}D$ states were also determined.