Berlin 2001 – scientific programme
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A: Atomphysik
A 10: Posters Wednesday (Cooling and Trapping, Electron Scattering and Recombination)
A 10.14: Poster
Wednesday, April 4, 2001, 12:30–15:00, AT3
Formation and decay of hollow carbon ions during electron impact ionization — •J. Jacobi, K. Ariki, H. Knopp, S. Schippers, and A. Müller — Institut für Kernphysik, Universität Giessen, Germany
In case of the triple ionization of C2+ two different reaction channels are possible. The first one is the direct ionization of 3 outer electrons. The second process is the formation of a hollow ion by simultaneously removing the two K-shell electrons. This hollow ion then decays by emitting one further electron in an Auger process, so that a C5+ ion is produced. Investigations of the electron impact ionization of C2+ have been made with an electron ion crossed beam setup. Cross sections of triple ionization of C2+ have been measured in an energy range between 300 eV and 1050 eV. A clear onset of hollow ion formation is observed at around 800 eV, the minimum energy for double K-shell ionization. At higher energies the corresponding cross section rises up to 6×10−23 cm2.