Dresden 2011 – scientific programme

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A: Fachverband Atomphysik

A 22: Electron scattering and recombination I

A 22.4: Talk

Thursday, March 17, 2011, 15:00–15:15, BAR 106

Electron impact excitation of highly-charged ions — •Lalita Sharma^1,2, Andrey Surzhykov^1,2, Rajesh Srivastava³, and Stephan Fritzsche^2,4 — ¹Physikalisches Institut der Universität Heidelberg — ²GSI Helmholtzzentrum für Schwerionenforschung GmbH — ³Indian Institute of Technology Roorkee, India — ⁴Department of Physical Sciences, University of Oulu, Finland

During the last decade, electron impact excitation of few–electron ions has been explored intensively both at electron beam ion traps (EBIT) and ion storage ring facilities. In these studies, particular attention has been paid to the linear polarization of the subsequent characteristic photon emission. Such a (fluorescence) polarization can be used as a precise tool for the plasma diagnostic as well as for better understanding of the relativistic and many–body effects in electron-ion collisions. In this contribution, a fully–relativistic distorted–wave code was developed by us recently, and has been employed to investigate electron impact excitation of highly charged ions. Detailed calculations have been performed, in particular, for the K → L excitation of hydrogen–like Ar¹⁷⁺, Ti²¹⁺ and Fe²⁵⁺ ions for a wide range of collision energies. Apart from the total cross sections theoretical predictions were obtained for the alignment parameters of the excited ionic states and, hence, for the polarization of the characteristic Lyman–α lines. Results of our calculations are compared with the available experimental and theoretical data.