Spin-orbit relaxation of cesium7 2Din mixtures of helium and argon

Abstract

Pulsed excitation on the two-photon Cs $6{\phantom{\rule{0.16em}{0ex}}}^{2}{S}_{1/2}\ensuremath{\rightarrow}7{\phantom{\rule{0.16em}{0ex}}}^{2}{D}_{3/2,5/2}$ transition results in time-resolved fluorescence at 697 and 672 nm. The rates for fine-structure mixing between the $7{\phantom{\rule{0.16em}{0ex}}}^{2}{D}_{3/2,5/2}$ states have been measured for helium and argon rare-gas collision partners. The mixing rates are very fast, $1.26\ifmmode\pm\else\textpm\fi{}0.05\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}9} {\mathrm{cm}}^{3}$/atom s for He and $1.52\ifmmode\pm\else\textpm\fi{}0.05\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10} {\mathrm{cm}}^{3}$/atom s for Ar, driven by the small energy splitting and large radial distribution for the valence electron. The quenching rates are considerably slower, $6.84\ifmmode\pm\else\textpm\fi{}0.09\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}11}$ and $2.65\ifmmode\pm\else\textpm\fi{}0.04\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}11} {\mathrm{cm}}^{3}$/atom s for He and Ar, respectively. The current results are placed in context with similar rates for other alkali-metal--rare-gas collision pairs using adiabaticity arguments.