Autoionization of He and Autodetachment of He\u3csup\u3e-\u3c/sup\u3e following Bombardment by H\u3csup\u3e+\u3c/sup\u3e, H\u3csub\u3e2\u3c/sub\u3e\u3csup\u3e+\u3c/sup\u3e, He\u3csup\u3e+\u3c/sup\u3e, and He Atoms

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