Mainz 2017 – wissenschaftliches Programm
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A: Fachverband Atomphysik
A 20: Poster Session I
A 20.16: Poster
Dienstag, 7. März 2017, 17:00–19:00, P OG1
Multi-electron processes in K-shell double and triple photodetachment of oxygen anions — •Stefan Schippers1, Randolph Beerwerth2,3, Levente Abrok4, Sadia Bari5, Ticia Buhr1, Michael Martins6, Sandor Ricz4, Jens Viefhaus5, Stephan Fritzsche2,3, and Alfred Müller1 — 1Justus-Liebig-Universität Gießen — 2Helmholtz-Institut Jena — 3Friedrich-Schiller-Universität Jena — 4ATOMKI, Debrecen, Hungary — 5DESY, Hamburg — 6Universität Hamburg
The photon-ion merged-beams technique was used at a synchrotron light source for measuring absolute cross sections of double and triple photodetachment of O− ions [1]. The experimental photon energy range of 524–543 eV comprised the threshold for K-shell ionization. Using resolving powers of up to 13000, the position, strength and width of the below-threshold 1s 2s2 2p6 2S resonance as well as the positions of the 1s 2s2 2p5 3P and 1s 2s2 2p5 1P thresholds for K-shell ionization were determined with high-precision. In addition, systematically enlarged multi-configuration Dirac-Fock calculations have been performed for the resonant detachment cross sections. Results from these ab initio computations agree very well with the measurements for the widths and branching fractions for double and triple detachment, if double shake-up (and -down) of the valence electrons and the rearrangement of the electron density is taken into account. For the absolute cross sections, however, a previously found discrepancy between measurements and theory is confirmed.
S. Schippers et al., Phys. Rev. A 94 (2016) 041401(R).