Atomic data from the IRON Project = 2, 3, 4 configurations. LVI. Electron excitation of Belike Fe XXIII for the n = 2,3,4 configurations
Abstract
Collision strengths for electron induced transitions in the berylliumlike ion Fe^{+22} are calculated using the intermediate coupling frame transformation (ICFT) version of the Rmatrix programs. Our target has 98 fine structure states 1s^{2} nl n'l' SLJ corresponding to n = 2 and n' = 2, 3, 4 . The present calculation is for electron impact energies in the range 3.15 to 380 Ry. When T exceeds about ten million degrees one needs to take account of contributions to the thermally averaged collision strength Υ coming from electrons with energies in excess of 380 Ry. We discuss a way of allowing for these contributions. Values of Υ for all the transitions between the ground state and the excited states 1s^{2} 2l n l n'l' S'L'J', with n'=2,3,4 are tabulated as a function of log T. The temperature range 6.3 ≤log T ≤8.1 is centred on log T = 7.1 which is approximately where Fe^{+22} has maximum abundance in ionization equilibrium. To the best of our knowledge these are the first Rmatrix calculations for Fe^{+22} for excitations to the n = 3,4 levels. Good agreement with previous distoredwave calculations is found. However, the resonance contributions have an important effect on the effective collision strengths and in turn on the level populations.
Full Tables 2, 4 and 6 are only available in electronic form at the CDS via anonymous ftp to cdsarc.ustrasbg.fr (130.79.128.5) or via http://cdsweb.ustrasbg.fr/cgibin/qcat?J/A+A/430/331. The full datasets of wavelengths and gf values (Table 4) and of effective collision strengths (Table 7) are only available at the same address. The same data are also available at the TIPbase (http://vizier.ustrasbg.fr/tipbase/home.html) database and as an `adf04' file at the Oak Ridge National Laboratory's database via http://wwwcfadc.phy.ornl.gov/
 Publication:

Astronomy and Astrophysics
 Pub Date:
 January 2005
 DOI:
 10.1051/00046361:20041358
 Bibcode:
 2005A&A...430..331C
 Keywords:

 atomic data;
 Sun: corona