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Two-electron processes in multiple ionization under strong soft-x-ray radiation

Ilchen, M.; Mazza, T.; Karamatskos, E. T.; Markellos, D.; Bakhtiarzadeh, S.; Rafipoor, A. J.; Costello, J. T.; Walsh, N.; Kelly, T. J.; O'Keeffe, P.; Gerken, N.; Martins, M.; Lambropoulos, P.; Meyer, M.

Authors

M. Ilchen

P. O'Keeffe

N. Gerken

M. Martins

P. Lambropoulos

M. Meyer

T. Mazza

E. T. Karamatskos

D. Markellos

S. Bakhtiarzadeh

A. J. Rafipoor

J. T. Costello

N. Walsh

T. J. Kelly

Abstract

In a combined experimental and theoretical study we have investigated the ionization of atomic argon upon irradiation with intense soft-x-ray pulses of 105 eV photon energy from the free-electron laser FLASH. The measured ion yields show charge states up to Ar7+. The comparison with the theoretical study of the underlying photoionization dynamics highlights the importance of excited states in general and of processes governed by electron correlation in particular, namely, ionization with excitation and shake-off, processes usually inaccessible by measurements of ionic yields only. The Ar7+ yield shows a clear deviation from the predictions of the commonly used model of sequential ionization via single-electron processes and the observed signal can only be explained by taking into account the full multiplet structure of the involved configurations and by inclusion of two-electron processes. The competing process of two-photon ionization from the ground state of Ar6+ is calculated to be orders of magnitude smaller.

Journal Article Type Article
Publication Date Jul 18, 2016
Journal Physical review a
Print ISSN 2469-9926
Electronic ISSN 2469-9934
Publisher American Physical Society
Peer Reviewed Peer Reviewed
Volume 94
Issue 1
Article Number ARTN 013413
Pages 013413-1-013413-11
DOI https://doi.org/10.1103/PhysRevA.94.013413
Keywords Photoionization
Publisher URL https://journals.aps.org/pra/abstract/10.1103/PhysRevA.94.013413
Additional Information This is the author's accepted version of an article published in: Physical review a, 2016, v.94.

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