He(2<sup>1</sup>S) and He<sup>-</sup> formation in fast charge-changing collisions and evidence for a long-lived doublet state of He<sup>-</sup>
K F Dunn; B J Gilmore; F R Simpson; H B Gilbody; K F Dunn; Dept. of Pure & Appl. Phys., Queen's Univ. Belfast, UK; B J Gilmore; Dept. of Pure & Appl. Phys., Queen's Univ. Belfast, UK; F R Simpson; Dept. of Pure & Appl. Phys., Queen's Univ. Belfast, UK; H B Gilbody; Dept. of Pure & Appl. Phys., Queen's Univ. Belfast, UK
Журнал:
Journal of Physics B: Atomic and Molecular Physics
Дата:
1978-05-28
Аннотация:
The formation of fast metastable helium atoms in two-electron capture by 200 keV <sup>4</sup>He<sup>2+</sup> ions in passage through hydrogen has been studied by means of the beam-attenuation technique. The results have been compared with metastable formation in one-electron capture by He<sup>+</sup> ions. The cross section for the process He<sup>2+</sup>+H<sub>2</sub> to He(2<sup>1</sup>S)+H<sup>+</sup>+H<sup>+</sup> which necessarily leads to 2<sup>1</sup>S rather than 2<sup>3</sup>S formation has been determined. The formation of He<sup>-</sup> ions in one-electron capture by 200 keV He(2<sup>1</sup>S) and (2<sup>3</sup>S) atoms has also been studied. The cross section for capture by 2<sup>1</sup>S atoms is shown to be approximately one half that for capture by 2<sup>3</sup>S atoms.
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