Paper XXIV

Electron excitation of Li-like Fe XXIV between the $n=2$ and $n^\prime=2,3,4$ fine-structure levels

K.A. Berrington and J.A. Tully

Astronomy & Astrophysics Supplement Series, 1997, Vol.126, pp.105-111

Collision strengths for electron induced transitions in Li-like Fe XXIV are calculated using a Breit-Pauli R-matrix technique. The target has 15 fine structure states corresponding to $n\le 4$. Autoionizing resonances are found to affect 18 of the 39 collision strengths, namely those for transitions $2lj\rightarrow n^\prime l^\prime j^\prime$ where $n^\prime = 2,3$. The present calculation is carried out only for electrons incident on the ground state with energies not exceeding 265 Ry. Beyond this we use the relativistic distorted wave collision strengths of Zhang et al. in order to complete our results. Thermally averaged collision strengths are computed and tabulated as functions of $\log T$ for transitions out of the 2s$_{1/2}$, 2p$_{1/2}$ and 2s$_{3/2}$ states. The temperature range considered is $6.2\le \log T \le 8.0$, Fe XXIV having its maximum coronal abundance when $\log T = 7.2$.