Cross sections for the K-shell photoabsorption of neutral iron

The Fe I K alpha emission lines are observed during solar flares and in the emission spectra of other astrophysical sources, such as active galactic n uclei. This paper presents cross sections for the K-shell photoionization o f neutral iron, which are urgently required for the modeling of these astro physical phenomena. A 16 target-state representation is utilized, where eac h target state is represented by an extensive configuration-interaction-typ e wave function. The consequent introduction of electron correlation effect s is seen to significantly alter the magnitude of the background cross sect ion in comparison with earlier work, while extensive resonance structure is also resolved near threshold for the first time.