Berlin 2001 – wissenschaftliches Programm
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A: Atomphysik
A 10: Posters Wednesday (Cooling and Trapping, Electron Scattering and Recombination)
A 10.19: Poster
Mittwoch, 4. April 2001, 12:30–15:00, AT3
Resonant versus direct processes in electron impact ionization of Li-like ions — •A. Müller1, K. Aichele1, H. Knopp1, R. A. Phaneuf2, S. Ricz3, E. Salzborn1, F. Scheuermann1, S. Schippers1, W. Shi1, and H. Teng1 — 1Universität Giessen, Germany — 2University of Nevada, Reno, USA — 3ATOMKI Institute for Nuclear Research, Debrecen, Hungary
In the electron-impact ionisation of Li-like ions, in addition to the direct ionization (DI) of either a K-shell or L-shell electron, three important indirect processes can contribute to the total ionization cross section. We report on a detailed experimental and theoretical study of these processes for the ionization of C3+,O5+ and Ne7+. High resolution scan measurements of the K-shell excitation threshold region have been performed with statistical uncertainities as low as 0.03%. At this level of precision a wealth of features in the cross sections become visible, and even interference of direct ionization with resonant-excitation/auto-double-ionization (READI) and interference between the excitation/auto-ionization (EA) and the resonant-excitation/double-autoionization (REDA) are clearly observed. The experimental results are compared with R-matrix calculations that treat all processes (direct and indirect) in a unified manner. The calculations are in very good agreement with the experimental cross sections for all 3 ions.