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Abstract
We review recent work on the photoionization of atomic ions of astrophysical interest that has been carried out at the photon-ion merged-beams setup PIPE, a permanently installed end station at the XUV beamline P04 of the PETRA III synchrotron radiation source operated by DESY in Hamburg, Germany. Our results on single and multiple L-shell photoionization of Fe+, Fe2+, and Fe3+ ions, and on single and multiple K-shell photoionization of C−, C+, C4+, Ne+, and Si2+ ions are discussed in astrophysical contexts. Moreover, these experimental results bear witness of the fact that the implementation of the photon-ion merged-beams method at one of the world’s brightest synchrotron light sources has led to a breakthrough for the experimental study of atomic inner-shell photoionization processes with ions.
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Madesis I, Laoutaris A, Zouros TJM, Benis EP, Gao JW, Dubois A. Pauli Shielding and Breakdown of Spin Statistics in Multielectron Multi-Open-Shell Dynamical Atomic Systems. PHYSICAL REVIEW LETTERS 2020; 124:113401. [PMID: 32242719 DOI: 10.1103/physrevlett.124.113401] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 02/10/2020] [Accepted: 02/22/2020] [Indexed: 06/11/2023]
Abstract
We report on C^{3+}(1s2ℓ2ℓ^{'} ^{2S+1}L)-resolved cross sections of electron capture in collisions of swift C^{4+}(1s2s ^{3}S) ions with helium and hydrogen. The study focuses on the formation of doubly excited triply open-shell C^{3+}(1s2s2p) ^{4}P and ^{2}P_{±} states with emphasis on the ratio R of their cross sections as a measure of spin statistics. Using zero-degree Auger projectile spectroscopy and a three-electron close-coupling semiclassical approach, we resolve a long-standing puzzle and controversy on the value of R and on the effect of cascades, to clarify the underlying physics. The present results invalidate the frozen core approximation generally used in the past when considering electron capture in multielectron multi-open-shell quantum systems. A distinctive screening effect due to the Pauli exclusion principle (Pauli shielding) is proposed to account for the value of R, consistent with our findings.
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Affiliation(s)
- I Madesis
- Department of Physics, University of Crete, GR-70013 Heraklion, Greece and Tandem Accelerator Laboratory, Institute of Nuclear and Particle Physics, NCSR "Demokritos", GR-15310 Agia Paraskevi, Greece
| | - A Laoutaris
- Department of Physics, University of Crete, GR-70013 Heraklion, Greece and Tandem Accelerator Laboratory, Institute of Nuclear and Particle Physics, NCSR "Demokritos", GR-15310 Agia Paraskevi, Greece
| | - T J M Zouros
- Department of Physics, University of Crete, GR-70013 Heraklion, Greece and Tandem Accelerator Laboratory, Institute of Nuclear and Particle Physics, NCSR "Demokritos", GR-15310 Agia Paraskevi, Greece
| | - E P Benis
- Department of Physics, University of Ioannina, GR-45110 Ioannina, Greece
| | - J W Gao
- Institute of Applied Physics and Computational Mathematics, 100088 Beijing, China, Laser Fusion Research Center, China Academy of Engineering Physics, 621900 Mianyang, China and Sorbonne Université, CNRS, Laboratoire de Chimie Physique-Matière et Rayonnement, F-75005 Paris, France
| | - A Dubois
- Sorbonne Université, CNRS, Laboratoire de Chimie Physique-Matière et Rayonnement, F-75005 Paris, France
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