Levels and rate coefficients of the Fe-L

A major challenge in X-ray spectral modeling is the Fe-L spectrum, which is basically a complex assembly of n>=3 to n=2 transitions of Fe ions in different ionization states, affected by a range of atomic processes such as collisional excitation, resonant excitation, radiative recombination, dielectronic recombination, and innershell ionization. In this paper we perform a large-scale theoretical calculation on each of the processes with the flexible atomic code (FAC), focusing on ions of FeXVII to FeXXIV that form the main body of the Fe-L complex.

The calculation includes a large set of energy levels with a broad range of quantum number n and l, taking into account the full-order configuration interaction and all possible resonant channels between two neighboring ions. The new data are found to agree within 20% with the recent individual R-matrix calculations for the main FeL lines, although the discrepancies become significantly larger for the weaker transitions, in particular for FeXVIII, FeXIX, and FeXX.