Multiple ionization and coupling effects in L-subshell ionization of heavy atoms by oxygen ions

M. Pajek, D. Banaś, J. Semaniak, J. Braziewicz, U. Majewska, S. Chojnacki, T. Czyżewski, I. Fijał, M. Jaskóła, A. Glombik, W. Kretschmer, D. Trautmann, G. Lapicki, T. Mukoyama

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Abstract

The multiple-ionization and coupling effects in L-shell ionization of atoms by heavy-ion impact have been studied by measuring the L x-ray production cross sections in solid targets of Au, Bi, Th, and U bombarded by oxygen ions in the energy range 6.4–70 MeV. The measured L x-ray spectra were analyzed using the recently proposed method accounting for the multiple-ionization effects, such as x-ray line shifting and broadening, which enables one to obtain the ionization probabilities for outer shells. The L-subshell ionization cross sections have been obtained from measured x-ray production cross sections for resolved [Formula Presented] [Formula Presented] and [Formula Presented] transitions using the L-shell fluorescence and Coster-Kronig yields being substantially modified by the multiple ionization in the M and N shells. In particular, the effect of closing of strong [Formula Presented] Coster-Kronig transitions in multiple-ionized atoms was evidenced and discussed. The experimental ionization cross sections for the [Formula Presented] [Formula Presented] and [Formula Presented] subshells have been compared with the predictions of the semiclassical approximation (SCA) and the ECPSSR theory that includes the corrections for the binding-polarization effect within the perturbed stationary states approximation, the projecticle energy loss, and Coulomb deflection effects as well as the relativistic description of inner-shell electrons. These approaches were further modified to include the L-subshell couplings within the “coupled-subshell model” (CSM). Both approaches, when modified for the coupling effects, are in better agreement with the data. Particularly, the predictions of the SCA-CSM calculations reproduce the experimental L-subshell ionization cross section reasonably well. Remaining discrepancies are discussed qualitatively, in terms of further modifications of the L-shell decay rates caused by a change of electronic wave functions in multiple-ionized atoms.

Original languageEnglish
Article number022705
Number of pages1
JournalPhysical Review A - Atomic, Molecular, and Optical Physics
Volume68
Issue number2
DOIs
Publication statusPublished - Jan 1 2003

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

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    Pajek, M., Banaś, D., Semaniak, J., Braziewicz, J., Majewska, U., Chojnacki, S., Czyżewski, T., Fijał, I., Jaskóła, M., Glombik, A., Kretschmer, W., Trautmann, D., Lapicki, G., & Mukoyama, T. (2003). Multiple ionization and coupling effects in L-subshell ionization of heavy atoms by oxygen ions. Physical Review A - Atomic, Molecular, and Optical Physics, 68(2), [022705]. https://doi.org/10.1103/PhysRevA.68.022705