Proceedings of the European Symposium on Frontiers in Science and Technology with Synchrotron Radiation

J. Phys. IV France 04 (1994) C9-401-C9-404
DOI: 10.1051/jp4:1994967

Argon 3s autoionization

S.L. Sorensen¹, T. Åberg², J. Tulkki³, E. Rachlew-Källne¹, G. Sundström¹ and M. Kirm<sup>4

1</sup>  Department of Physics I, Royal Institute of Technology, 10044 Stockholm, Sweden
²  Laboratory of Physics, Helsinki University of Technology, 02150 Espoo, Finland
³  Optoelectronics Laboratory, Helsinki University of Technology, 02150 Espoo, Finland
⁴  Department of Atomic Spectroscopy, University of Lund, 22362 Lund, Sweden

Abstract
Synchrotron radiation-excited ion mass spectrometry has been used to study the 3s3p⁶np (n≥4) resonances in argon at 25.0 - 29.3 eV. It is shown using a time-independent resonant scattering approach that the Fano formalism may be applied to overlapping resonances. For the Dubau-Seaton profile an exact expression of the closed-channel phase shift is obtained. We find that regarding the window character of the Ar 3s series the Fano parameters calculated using the multichannel multiconfiguration Dirac-Fock method are in good agreement with those derived from fitting a convoluted Fano function to the measured n = 4 autoionizing resonance. The Fano parameters are also derived from fits to the 5≤n≤8 resonances which tests the validity of this parametrization to overlapping members of an inner-valence electron resonance series. In contrast, a parametrization of the entire series based upon the Dubau-Seaton formula did not result in a good fit without modifications. Using the same value of the shape parameter we find, however, that the n = 4 resonance can be accurately represented by both the Fano and Dubau-Seaton profiles.

© EDP Sciences 1994