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Title: Photoionization of Ne Atoms and Ne + Ions Near the K Edge: PrecisionSpectroscopy and Absolute Cross-sections

Single, double, and triple photoionization of Ne + ions by single photons have been investigated at the synchrotron radiation source PETRA III in Hamburg, Germany. Absolute cross-sections were measured by employing the photon-ion merged-beams technique. Photon energies were between about 840 and 930 eV, covering the range from the lowest-energy resonances associated with the excitation of one single K-shell electron up to double excitations involving one K- and one L-shell electron, well beyond the K-shell ionization threshold. Also, photoionization of neutral Ne was investigated just below the K edge. The chosen photon energy bandwidths were between 32 and 500 meV, facilitating the determination of natural line widths. The uncertainty of the energy scale is estimated to be 0.2 eV. For comparison with existing theoretical calculations, astrophysically relevant photoabsorption cross-sections were inferred by summing the measured partial ionization channels. Discussion of the observed resonances in the different final ionization channels reveals the presence of complex Auger-decay mechanisms. The ejection of three electrons from the lowest K-shell-excited Ne + (1s2s 2p 6 2S 1/2) level, for example, requires cooperative interaction of at least four electrons.
Authors:
ORCiD logo [1] ;  [1] ;  [2] ;  [2] ;  [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [7] ;  [7] ; ORCiD logo [2]
  1. Justus-Liebig Univ., Giessen (Germany). Inst. of Atomic and Molecular Physics (IAMP)
  2. Justus-Liebig Univ., Giessen (Germany). Inst. of Atomic and Molecular Physics (IAMP), Physical Inst.
  3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source
  4. Univ. of Hamburg (Germany). Inst. for Experimental Physics; Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Photon Science
  5. Univ. of Hamburg (Germany). Inst. for Experimental Physics
  6. Inst. of Nuclear Research of the Hungarian Academy of Sciences, Debrecen (Hungary)
  7. Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Photon Science
Publication Date:
Grant/Contract Number:
AC02-05CH11231
Type:
Accepted Manuscript
Journal Name:
The Astrophysical Journal (Online)
Additional Journal Information:
Journal Name: The Astrophysical Journal (Online); Journal Volume: 836; Journal Issue: 2; Journal ID: ISSN 1538-4357
Publisher:
Institute of Physics (IOP)
Research Org:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; atomic data; atomic processes; ISM: atoms; line: identification; line: profiles; opacity
OSTI Identifier:
1393123