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Elastic electron scattering by laser-excited 138Ba( ... 6s6p 1P1) atoms

Trajmar, S. and Kanik, I. and Khakoo, M. A. and LeClair, L. R. and Bray, I. and Fursa, D. and Csanak, G. (1999) Elastic electron scattering by laser-excited 138Ba( ... 6s6p 1P1) atoms. Journal of Physics B: Atomic, Molecular and Optical Physics, 32 (12). pp. 2801-2829. ISSN 0953-4075. http://resolver.caltech.edu/CaltechAUTHORS:TRAjpb99

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Abstract

The results of a joint experimental and theoretical study concerning elastic electron scattering by laser-excited 138Ba( ... 6s6p 1P1) atoms are described. These studies demonstrate several important aspects of elastic electron collisions with coherently excited atoms, and are the first such studies. From the measurements, collision and coherence parameters, as well as cross sections associated with an atomic ensemble prepared with an arbitrary in-plane laser geometry and linear polarization (with respect to the collision frame), or equivalently with any magnetic sublevel superposition, have been obtained at 20 eV impact energy and at 10°, 15° and 20° scattering angles. The convergent close-coupling (CCC) method was used within the non-relativistic LS-coupling framework to calculate the magnetic sublevel scattering amplitudes. From these amplitudes all the parameters and cross sections at 20 eV impact energy were extracted in the full angular range in 1° steps. The experimental and theoretical results were found to be in good agreement, indicating that the CCC method can be reliably applied to elastic scattering by 138Ba( ... 6s6p 1P1) atoms, and possibly to other heavy elements when spin-orbit coupling effects are negligible. Small but significant asymmetry was observed in the cross sections for scattering to the left and to the right. It was also found that elastic electron scattering by the initially isotropic atomic ensemble resulted in the creation of significant alignment. As a byproduct of the present studies, elastic scattering cross sections for metastable 138Ba atoms were also obtained.


Item Type:Article
Additional Information:© 1999 IOP Publishing Ltd. Received 10 August 1998, in final form 22 February 1999. This work was supported by the National Science Foundation, the National Aeronautics and Space Administration and the Department of Energy in the USA and by the South Australian Centre for High Performance Computing and Communications in Australia. One of us (LRL), wishes to thank the National Research Council for the Resident Research Associateship appointment. The authors wish to thank T Fujimoto and SAKazantsev for calling our attention to the question raised in connection with the creation of alignment in elastic electron collisions and its importance in plasma polarization spectroscopy as well as for valuable discussions. We also wish to acknowledge valuable discussions with D C Cartwright and P W Zetner and the help of M B Das in preparing the manuscript.
Record Number:CaltechAUTHORS:TRAjpb99
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:TRAjpb99
Alternative URL:http://dx.doi.org/10.1088/0953-4075/32/12/302
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:669
Collection:CaltechAUTHORS
Deposited By: Archive Administrator
Deposited On:13 Sep 2005
Last Modified:26 Dec 2012 08:40

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