Electron-impact coherence parameters for excitation of the /sup 1/P states in helium

Journal Article · Thu Sep 15 04:00:00 EDT 1988 · Phys. Rev. A; (United States)

DOI:https://doi.org/10.1103/PhysRevA.38.2740· OSTI ID:6764290

Csanak, G; Cartwright, D C

First-order many-body theory (FOMBT) has been used to calculate differential cross sections (DCS's) and electron-impact coherence parameters (EICP's) associated with excitation of the n/sup 1/P (n = 2,3) electronic states of helium for incident-electron energies in the range 22 eV less than or equal toEless than or equal to500 eV. The DCS's predicted by FOMBT agree reasonably well with the available experimental data and in the 50 eV less than or equal toEless than or equal to500 eV energy range, as well as, or better than, those predicted by any other theory. The EICP's predicted by R-matrix methods are found to agree better with the available experimental data in the threshold region (Eless than or equal to30 eV) than those predicted by FOMBT. However, in the intermediate-energy region, 50 eV less than or equal toEless than or equal to500 eV, FOMBT provides EICP results that are in semiquantitative agreement with the available data. Partial-wave decompositions of the parameter at various incident-electron energies show that the structure observed in this parameter is caused by interference among the free-electron partial waves and that the small-angle characteristics of this parameter are determined principally by low-l partial waves, i.e., by incident electrons with small-impact parameters. Additional experimental measurements and results from more elaborate calculations at intermediate and large scattering angles and for intermediate and high incident-electron energies are needed to resolve a number of issues associated with the interpretation of the EICP's.

• Research Organization: Los Alamos National Laboratory, University of California, Los Alamos, New Mexico 87545
• OSTI ID: 6764290
• Journal Information: Phys. Rev. A; (United States), Journal Name: Phys. Rev. A; (United States) Vol. 38:6; ISSN PLRAA
• Country of Publication: United States
• Language: English

Related Subjects

640304* -- Atomic
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
ATOM COLLISIONS
COLLISIONS
CROSS SECTIONS
DIFFERENTIAL CROSS SECTIONS
ELECTRON COLLISIONS
ELECTRON-ATOM COLLISIONS
ELEMENTS
ENERGY-LEVEL TRANSITIONS
EXCITATION
FINE STRUCTURE
FLUIDS
GASES
HELIUM
INELASTIC SCATTERING
MANY-BODY PROBLEM
NONMETALS
RARE GASES
SCATTERING