Title: Cross Sections for the De-Excitation of Helium Metastable Atoms by Collisions with Atoms
Abstract:The lifetimes of metastable helium atoms $\mathrm{He}(2^{3}S)$ and $\mathrm{He}(2^{1}S)$ were measured by a time-resolved optical absorption technique in the afterglow of a pulsed helium discharge at ...The lifetimes of metastable helium atoms $\mathrm{He}(2^{3}S)$ and $\mathrm{He}(2^{1}S)$ were measured by a time-resolved optical absorption technique in the afterglow of a pulsed helium discharge at 10-mm pressure with small concentrations of various impurity gases added. The following de-excitation cross sections in units of ${10}^{\ensuremath{-}16}$ ${\mathrm{cm}}^{2}$ have been determined for $\mathrm{He}(2^{3}S)$: Ne---0.28, Ar---6.6, Kr---10.3, Xe---13.9, ${\mathrm{N}}_{2}$---6.4, and ${\mathrm{H}}_{2}$---6.0. The uncertainties are estimated to be \ifmmode\pm\else\textpm\fi{}20% for the rare gases and \ifmmode\pm\else\textpm\fi{}50% for the molecular gases. $\mathrm{He}(2^{1}S)$ cross sections were measured to be Ne---4.1, Ar---55, Kr---64, and Xe---103, all times ${10}^{\ensuremath{-}16}$ ${\mathrm{cm}}^{2}$. The neon cross section is believed reliable to \ifmmode\pm\else\textpm\fi{}20% but the remaining singlet cross sections may be too high by as much as a factor 2 or 3. The cross sections refer to de-excitation by ionizing collisions except in the case of neon where neon excitation occurs. Competing destruction processes render the singlet cross-section analysis somewhat uncertain except in the case of neon.Read More
Publication Year: 1962
Publication Date: 1962-10-01
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 129
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