Energy and Angular Distributions of Electrons from Ion Impact on Atomic and Molecular Hydrogen. III. 28–114-keV He⁺ + H₂

Authors

Y.-Y. Hsu, University of Nebraska - Lincoln
M. W. Gealy, University of Nebraska - Lincoln
G. W. Kerby III, University of Nebraska - Lincoln
M. Eugene Rudd, University of Nebraska - LincolnFollow

Date of this Version

1-1996

Comments

Published in Physical Review A Volume 53, Number 1, January 1996. Copyright © American Physical Society; used by permission.

Abstract

Absolute cross sections, differential in energy and angle of ejection of the secondary electrons, were determined for electron emission from He⁺ +H₂ collisions at 28–114 keV by measuring electron energy spectra from 1.5 to 300 eV at several angles from 15° to 160°. A rotatable electrostatic analyzer was used with an energy resolution of 5% and an angular acceptance of 4.6° full width at half maximum. The double-differential cross sections were integrated over angle, energy, or both to obtain single-differential and total ionization cross sections. The latter are in excellent agreement with previous experimental results. Agreement of the experimental double-differential cross sections with plane-wave Born approximation calculations is generally poor. The cross section for ejection of high-energy electrons by He⁺ is considerably larger than that for H⁺ at the same velocity. This is attributed mostly to electron emission from the projectile. The presence of prominent Doppler-shifted helium autoionization peaks in the spectra indicates an appreciable probability for electron capture by the helium ions with simultaneous double excitation.