Electron-impact excitation of the n<sup>3,1</sup>S and n<sup>3,1</sup>P (n=2, 3 and 4) states of helium at low energies
W C Fon; K P Lim; K A Berrington; T G Lee; W C Fon; Dept. of Math., Malaya Univ., Kuala Lumpur, Malaysia; K P Lim; Dept. of Math., Malaya Univ., Kuala Lumpur, Malaysia; K A Berrington; Dept. of Math., Malaya Univ., Kuala Lumpur, Malaysia; T G Lee; Dept. of Math., Malaya Univ., Kuala Lumpur, Malaysia
Журнал:
Journal of Physics B: Atomic, Molecular and Optical Physics
Дата:
1995-04-28
Аннотация:
The 19-state and 29-state R-matrix calculations are employed to obtain the differential cross sections and electron-photon coincidence parameters for the 1<sup>1</sup>S-n<sup>3,1</sup>S and 1<sup>1</sup>S-n<sup>3,1</sup>P (n=2, 3 and 4) excitation of helium at energies ranging from the ionization threshold to 31.2 eV. The scattering angle ranges from 0 degrees to 180 degrees . The results are compared with the experiments and the latest calculation of Bray and co-workers (1994) to estimate the contributions of the effects of ionization continuum. Attempts are also made to show that the angular distribution of scattered electrons of the same incident velocity that have excited the n<sup>3,1</sup>S (or n<sup>3,1</sup>P) levels of helium for n=2, 3 and 4 are almost identical when fitted together at one angle.
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