Electron scattering by Rb, Cs, and Fr targets at low energies

C. Bahrim
(Dept. of Physics, Kansas State University, Manhattan, KS,
and Chemistry and Physics Dept., Lamar University, Beaumont, TX)

U. Thumm
(Dept. of Physics, Kansas State University, Manhattan, KS)

I. I. Fabrikant
(Dept. of Physics and Astronomy, University of Nebraska, Lincoln, NE)

Within the relativistic Dirac R-matrix method and a model based on an effective two-electron approach1, we analyze the spectra of Rb-, Cs-, and Fr- ions in electron scattering by Rb, Cs, and Fr targets at energies below 2.8 eV. Our calculations predict the same 3Po,e , 3Fo, and 1Po resonances for all three anions2 in calculations of angle-dependent, momentum transfer, and total cross sections. We discuss relativistic effects in the resonance profiles. Our 1+ partial cross sections show pronounced Ramsauer-Townsend (RT) minima at 41/46/32 meV for Rb/Cs/Fr, caused by the strong atomic polarizability and related to a 3Se virtual state. In the total converged cross section these RT minima are shifted to lower energies (4.6/1.1 meV for Rb/Cs, and below 1 meV for Fr) due to the nearby 3Po resonance. We also discuss our spin-flip and spin-exchange cross sections for e- + Rb, Cs, and Fr collisions in comparison with experimental data.


1) U. Thumm and D.W. Norcross Phys.Rev.A 45, 6349 (1992).
2) C. Bahrim, U. Thumm, and I.I. Fabrikant Phys.Rev.A 63, 042710 (2001)

This work was supported by the Chemical Sciences, Geosciences and Biosciences Division,
Office of Basic Energy Sciences, Office of Science, U.S. Department of Energy.

Submitted to DAMOP 2002, May 2002 in Williamsburg, VA.

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