Energy and angular distribution of electrons ejected from autoionization states in helium by electron impact. [65 to 1000 eV, differential cross sections]

Journal Article · Tue Feb 01 00:00:00 EST 1977 · Phys. Rev., A; (United States)

DOI:https://doi.org/10.1103/PhysRevA.15.574· OSTI ID:7236499

Oda, N; Tahira, S; Nishimura, F; Koike, F

Energy spectra of electrons ejected from autoionization states in helium by electron impact have been extensively measured for primary energies from 65 to 1000 eV and for ejection angles from 13degree to 142degree. The line shape in energy spectra undergoes a noticeable change with ejection angle as well as impact energy, reflecting the characteristics of the corresponding autoionization state. The single differential cross sections (differential in angle) for emissions of autoionized electrons have been obtained by integrating the energy spectra in the vicinity of each isolated resonance with respect to the energy after subtraction of the continuum background, for the (2s/sup 2/)/sup 1/S, (2s2p)/sup 3/P, (2p/sup 2/)/sup 1/D, and (2s2p)/sup 1/P states as a function of primary energy at 33degree, 127degree, and 142degree. Profiles of the spectra due to the (2s/sup 2/)/sup 1/S state have been analyzed using Fano's formula, and the shape parameter q is given as a function of ejection angle for 250-eV impact. A number of the autoionization states lying above approx. 62 eV have also been measured and identified as members of the (2sns)/sup 1/S, (2pnp)/sup 1/S, (sp2n-)/sup 3/P, (2pnp)/sup 1/D, and (sp2n+)/sup 1/P (n = 2--5) series, and our results are compared with previous results of theory and experiment. (AIP)

• Research Organization: Research Laboratory of Nuclear Reactor, Tokyo Institute of Technology, Meguro-ku, Tokyo, Japan
• OSTI ID: 7236499
• Journal Information: Phys. Rev., A; (United States), Vol. 15:2
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
ELECTRON-ATOM COLLISIONS
IONIZATION
HELIUM
ANGULAR DISTRIBUTION
DIFFERENTIAL CROSS SECTIONS
ENERGY SPECTRA
EV RANGE 10-100
EV RANGE 100-1000
EXCITED STATES
ATOM COLLISIONS
COLLISIONS
CROSS SECTIONS
CRYOGENIC FLUIDS
DISTRIBUTION
ELECTRON COLLISIONS
ELEMENTS
ENERGY LEVELS
ENERGY RANGE
EV RANGE
FLUIDS
NONMETALS
RARE GASES
SPECTRA
640304* - Atomic
Molecular & Chemical Physics- Collision Phenomena