Electron impact excitation of Fe XIX |
K. Butler and C.J. Zeippen |
Astronomy & Astrophysics, 2001, Vol.372, pp.1083 |
Collision strengths and collisional rate parameters have been calculated for
transitions among 92 n=2 and n=3 levels of O-like Fe XIX. The method used is
the Breit-Pauli R-matrix formalism in which most prominent relativistic effects
are accounted for. Partial wave contributions up to J=59/2 are included
explicitly while ``top-up'' procedures complete the sum to infinity. Several
thousand energy points were used to fully incorporate the effect of resonances
in the collisional cross sections when estimating the collisional rate
parameters. This is particularly important at lower temperatures
where the resonant contributions dominate. The present results are
expected to be accurate to better than 20% for transitions among n=2 levels.