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

The total quenching cross sections for He(n1,3S)(2≤n≤11) 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 to 10^-14, cm². 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≥1 states.