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A: Fachverband Atomphysik
A 24: Photoionization
A 24.1: Talk
Thursday, March 13, 2008, 14:00–14:15, 3D
One-photon two-electron processes in Helium: Unity and diversity — •Celsus Bouri1,2,3, Laurence Malegat2, Patricia Selles2, and Moïse Kwato Njock3 — 1Quantum Optics and Statistics, Institute of Physics, Albert-Ludwigs-Universität Freiburg, Hermann-Herder Str.3, D-79104 Freiburg, Germany — 2LIXAM, Bât. 350, Université Paris Sud, F-91405 Orsay, France — 3CEPAMOQ, Université de Douala, B.P. 8580, Douala, Cameroon
The ab-initio HRM-SOW method has established itself as the ideally fit tool to explore the three-body dynamics of the helium atom close to the three-body break-up threshold. Accordingly, it is used here to perform a numerical experiment designed to enlighten the relation between the various competing processes which may occur in the vicinity of the double ionization threshold, be it double excitation, excitation-ionization or double ionization. More precisely, double ionization and ionization-excitation cross sections are produced at 100 meV above the double ionization threshold. The latter, obtained up to as high a level as n=50, are in addition analyzed in terms of spherical and parabolic partial waves in the photoelectron frame. Based on these extensive data, we establish a continuity relation between ionization-excitation and double ionization appropriate to the near threshold, confirm previous qualitative predictions regarding the dominant angular momentum achieved in these near threshold excitation processes, evidence the relation between ionized-excited and doubly excited states, and promote the partial parabolic ionization-excitation cross sections as the optimal observation channels of doubly excited states.