A&A 418, 363-369 (2004)
Electron impact excitation of fine-structure levels in Cl IIS. S. Tayal
Department of Physics, Clark Atlanta University, Atlanta, GA 30314, USA
(Received 23 September 2003 / Accepted 7 November 2003 )
The B-spline basis has been used in the R-matrix approach to calculate electron impact excitation collision strengths for transitions between the , and levels and from these levels to the fine-structure levels of the excited , , , and configurations of Cl II. We considered 23 LS states , , , , , , , , , , , , , , , and in the close-coupling expansion that give rise to 51 fine-structure levels. The non-orthogonal orbitals are used for an accurate representation of both the target wavefunctions and the R-matrix basis functions. The collision strengths for transitions between fine-structure levels are calculated by transforming the LS-coupled K-matrices to K-matrices in an intermediate coupling scheme. The Rydberg series of resonances converging to excited state thresholds make substantial contributions to collision strengths. The thermally averaged collision strengths have been obtained by integrating collision strengths over a Maxwellian distribution of electron energies and these are listed in Table 2 for log T from 3.3 to 5.6 K.
Key words: atomic data -- atomic processes -- line: formation
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