State-changing inNa(ns,np)−Xecollisions

In thermal-energy collisions between sodium atoms in $\mathrm{ns}$ or $\mathrm{np}$ states ($32<~n<~52$) and xenon atoms, depopulation of the Rydberg states is observed to occur predominantly through state-changing reactions of the type $\mathrm{Na}(ns or np)+\mathrm{Xe}\to \mathrm{Na}(n-1, l>~2)+\mathrm{Xe}$. For the present range of $n$, the measured cross sections increase with $n$ and lie between 1500 and 2600 ${\mathrm{\AA }}^2$ for $\mathrm{ns}$ states and between 2000 and 4200 ${\mathrm{\AA }}^2$ for $\mathrm{np}$ states. Implications of the data are discussed.