Berlin 2001 – wissenschaftliches Programm

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A: Atomphysik

A 10: Posters Wednesday (Cooling and Trapping, Electron Scattering and Recombination)

A 10.15: Poster

Mittwoch, 4. April 2001, 12:30–15:00, AT3

Deep-Core Dielectronic-Capture Resonances in the Electron-Impact Ionization of Sm Ions — •F. Scheuermann¹, K. Aichele¹, W. Arnold¹, D. Hathiramani¹, A. Müller¹, E. Salzborn¹, D. Mitnik², J. Colgan², and M. S. Pindzola² — ¹Institut für Kernphysik, University of Giessen, Giessen, Germany — ²Department of Physics, Auburn University, Auburn, Alabama, USA

Experimental measurements and theoretical calculations have been carried out for the electron-impact ionization of Sm^q+ (q=5−12). The measurements have been performed using the dynamic crossed-beams technique from threshold up to 1 keV electron energy. The low energy region of the single ionization cross sections for Sm^q+ ions is found to be dominated by contributions of the indirect process of excitation-autoionization. Below 1 keV, strong resonance features are found in the measurements for single, double and triple ionization of Sm⁹⁺-Sm¹³⁺ performed in energy-scan mode at high resolution. Calculations for resonance energies and autoionization rates confirm that the observed resonances are due to dielectronic capture followed by sequential double, triple and quadruple Auger decay. Similar unusual high energy resonances are also found in ionization cross sections of Pr^q+ and Ba^q+ ions. This opens the door for future systematic studies of how heavy ions achieve final stabilization after dielectronic-capture.