Atomic data for the K-vacancy states of Fe XXIV

Abstract

As part of a project to compute atomic data for the spectral modeling of iron K lines, we report calculations and comparisons of atomic data for K-vacancy states in Fe XXIV. The data sets include: (i) energy levels, line wavelengths, radiative and Auger rates; (ii) inner-shell electron impact excitation rates and (iii) fine structure inner-shell photoabsorption cross sections. The calculations of energy levels and radiative and Auger rates have involved a detailed study of orbital representations, core relaxation, configuration interaction, relativistic corrections, cancellation effects and semi-empirical corrections. It is shown that a formal treatment of the Breit interaction is essential to render the important magnetic correlations that take part in the decay pathways of this ion. As a result, the accuracy of the present A-values is estimated at 10% while that of the Auger rates at 15%. The calculations of collisional excitation and photoabsorption cross sections take into account the effects of radiation and spectator Auger dampings. In collisional excitation, these effects cause significant attenuation of resonances leading to a good agreement with a simpler method where resonances are excluded. In photoabsorption. resonances converging to the K thresholds display symmetric profiles of constant width that causes edge smearing.