Deexcitation of Rydberg states of He by He, Ne, Ar, Kr, and Xe

The total quenching cross sections for $\mathrm{He}\left(n^{1,3}S\right)\left(2\mathrm{}\le n\le 11\right)$ states by thermal collisions [600(+ 200, - 100) K] with He, Ne, Ar, Kr, and Xe have been measured. The main quenching mechanism is attributed to Penning ionization for lower $n$, and collisional angular-momentum transfer for highly excited states. Measured cross sections are of the order of ${10}^{-15\mathrm{}}$ to ${10}^{-14\mathrm{}}$, ${\mathrm{cm}}^2$. The values for higher $n$ states are much smaller than the geometrical cross section; this is explained by a relatively large energy spread between the $S$ state and $l\ge 1$ states.