Evidence for significant backscattering in near-threshold electron-impact excitation ofAr7+(3s→3p)

1 January 1993

journal article
research article
Published by American Physical Society (APS) in Physical Review A

Vol. 47 (1) , R9-R12
https://doi.org/10.1103/physreva.47.r9

Abstract

Measurements of absolute total cross sections for electron-impact excitation of

{Ar}^{7 +}

(3s→3p) using a merged-beams electron-energy-loss technique show that near threshold the inelastically scattered electrons are ejected primarily in the backward direction. This unusual angular scattering has not been previously observed for atoms or ions, but may be typical for multiply charged ions. The total cross sections, measured over an energy range to 2.2 eV above threshold, agree with seven-state R-matrix close-coupling calculations. Both close-coupling and distorted-wave calculations also confirm the backscattering observed in these measurements.

Keywords

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