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Physical Review A

Ionization of low Rydberg He atoms by rotational deexcitation of N H3

A. Pesnelle, C. Ronge, M. Perdrix, G. Watel

Published Dec 1, 1986• 9 citations
Publisher

Abstract

Ionization of excited helium atoms in $n^{1}P(14\ensuremath{\le}n\ensuremath{\le}16)$ states due to collisions with the polar molecules N${\mathrm{H}}_{3}$ has been studied in a thermal energy crossed-beam experiment. A large ionization signal from these low Rydberg states is observed even though there is insufficient energy available from rotational $\ensuremath{\Delta}J=\ensuremath{-}1$, $\ensuremath{\Delta}K=0$ relaxation transitions of the molecule. In order to explain our observations, large $|\ensuremath{\Delta}J|$ transitions must be postulated.

DOI
10.1103/physreva.34.5146

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The ionization of low-Rydberg-state He atoms in the n 1P^{1}P1P state (n=14) in collisions with the polar molecules NH3{\mathrm{NH}}_{3}NH3​, SO2{\mathrm{SO}}_{2}SO2​, and acetone (C3{\mathrm{C}}_{3}C3​H6{\mathrm{H}}_{6}H6​O) is carried out in a crossed-beam experiment at thermal kinetic energies. The dependence of the experimental ionization cross sections ${\ensuremath{\sigma}}_{i}^{\mathrm{expt}}$ on the relative velocity of the reactants is obtained by a time-of-flight method. We observe that it varies mainly as 1/vr2{v}_{r}^{2}vr2​ in a large part of the studied velocity range, while a 1/vr{v}_{r}vr​ velocity dependence is predicted by the free-electron model for the higher Rydberg levels.
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