Autoionization of He and Autodetachment of He^- following Bombardment by H⁺, H₂⁺, He⁺, and He Atoms

Authors

F. D. Schowengerdt, University of Nebraska - Lincoln
S. R. Smart, University of Nebraska - Lincoln
M. Eugene Rudd, University of Nebraska - LincolnFollow

Date of this Version

1973

Comments

Published in Physical Review A 7, 560 - 566 (1973)
©1973 The American Physical Society
URL: http://link.aps.org/doi/10.1103/PhysRevA.7.560
DOI: 10.1103/PhysRevA.7.560

Abstract

Presented here are experimental results of a study of the systematics of electron emission from discrete states of He and He- as produced by H⁺, H₂⁺, He⁺, and He impacts. The results were obtained by energy analysis of the electrons emitted at angles of 10° to 160°. Projectile energies ranged from 20 to 150 keV. Differential and integrated cross sections are presented for emission of electrons from the 2s² (¹S), 2s2p(³P), the sum of the 2p² (¹D) and 2s2p(¹P) autoionizing levels of He, and the 1s2s² (²S) autodetaching level of He-. The 2s² (¹S) cross section is nearly isotropic, while the 2s2p(³P) and 2p² (¹D)+2s2p(¹P) cross sections are in general anisotropic. The ratios of the ³P to the ¹S cross sections follow an approximate A+Bcos²θ form. The peak arising from the He^- level has an asymmetric profile with a positive q value which increases as the projectile energy decreases.