Double-electron capture and population of Rydberg levels in slow Ar{sup 8+}+He collisions
- Universite de Marne-La-Vallee, 93166 Noisy-Le-Grand (France)
- DARC, Observatoire de Paris, F-92195 Meudon Cedex (France)
- CEA, Departement de Recherche Fondamentale sur la Matiere Condensee, AIM, 38054 Grenoble Cedex 9 (France)
- Laboratoire Aimee Cotton, Batiment 505, Universite Paris--Sud, 91405 Orsay (France)
Double-electron capture by Ar{sup 8+} from He is analyzed. Since the incident ion beam contains a metastable fraction of the order 5{percent}, two distinctly behaving systems are considered: (1) Ar{sup 8+}(2p{sup 6}){sup 1}S{sub 0}+He{r_arrow}Ar{sup 6+}(2p{sup 6}nln{sup {prime}}l{sup {prime}}){sup 2S+1}L{sub J}+He{sup 2+} and (2) Ar{sup 8+}(2p{sup 5}3s){sup 3}P{sub J}+He{r_arrow}Ar{sup 6+}(2p{sup 5}3snln{sup {prime}}l{sup {prime}}){sup 2S+1}L{sub J}+He{sup 2+}. For process (1), the comparison of translational energy gain and Auger spectra, with an extensive set of calculated data, supports the conclusion of an asymmetric double-electron transfer peaking at Ar{sup 6+}(2p{sup 6}3d4f) with a Rydberg tail getting to (3lnl{sup {prime}}) with n{congruent}20 (l=1,2). For process (2), the double capture points dominantly into triply excited states Ar{sup 6+}(2p{sup 5}3s3l4l{sup {prime}}){sup 2S+1}L{sub J}. These are above the second ionization limit of the ground state Ar{sup 6+}(2p{sup 6}3s{sup 2}){sup 1}S{sub 0}. Their decay takes place via two successive Auger steps: the first ending in the intermediate levels, Ar{sup 7+}(2p{sup 5}3l3l{sup {prime}}){sup 2,4}L{sub J}. These, in turn, autoionize to the Ar{sup 8+}(2p{sup 6}){sup 1}S{sub 0} continuum. Both are identified in the Auger spectrum. These observations raise the question of the meaning of the auto transfer to Rydberg states and of correlated double capture processes. {copyright} {ital 1997} {ital The American Physical Society}
- OSTI ID:
- 553063
- Journal Information:
- Physical Review A, Journal Name: Physical Review A Journal Issue: 6 Vol. 56; ISSN 1050-2947; ISSN PLRAAN
- Country of Publication:
- United States
- Language:
- English
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