Note on electron impact excitation for transition of Be-like isoelectronic sequence
Physics Department, National University of Singapore, Singapore 119260
Revised: 18 June 1998
Published online: 15 May 1999
Relativistic distorted-wave method was used to calculate the electron impact excitation collision strengths for transitions - of Be-like isoelectronic ions. The target states were described, respectively, by 10-level, 46-level and 133-level MCDF configuration-expansion. The relativistic continuum orbitals were calculated in the potential field of frozen target-ion charge distribution with semi-classical exchange potential. The influence of the target states on this collision process along the isoelectronic sequence was investigated in the above three MCDF configuration-expansion modes. It was found that the configurations in the n=3 and the n=4 complexes have great influence on both the high and the low Z ions but the influence is relatively small for intermediate Z ions. The latter phenomenon was attributed to competition between opposing correlation and relativistic effects on the collision strengths.
PACS: 34.50.Fa – Electronic excitation and ionization of atoms (including beam-foil excitation and ionization) / 34.80.Kw – Electron-ion scattering; excitation and ionization
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 1999