Berlin 2001 – wissenschaftliches Programm
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A: Atomphysik
A 10: Posters Wednesday (Cooling and Trapping, Electron Scattering and Recombination)
A 10.18: Poster
Mittwoch, 4. April 2001, 12:30–15:00, AT3
Electron impact ionization of He-like metastable C4+-ions — •H. Knopp, C. Böhme, S. Schippers, W. Shi, and A. Müller — Universität Giessen
Indirect mechanisms in electron impact ionization of atoms or ions require the presence of at least two electrons. With He-like targets in the ground state only two-electron excitation provides ionization channels additional to direct removal of one electron. With metastable He-like (1s2s) ions resonant and nonresonant excitation of the one K-Shell electron can lead to net single ionization of the original target by subsequent electron emission processes. Indirect contributions to the net single ionization of C4+ (1s2s) have been investigated with high energy resolution and high precision by using a crossed-beams apparatus. An ECR-ion source produces an ion beam with a mixture of ground state and (1s2s 3S) metastable ions. We were able to observe resonance structures in the ionization cross section, which are unambiguously associated with the metastable ions. The experimental results are compared to theoretical predictions.