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K-shell photoabsorption and photoionization

Description

This is the final report of a three-paper series on the K-shell photoabsorption and photoionization of trace elements (low cosmic abundance), namely F, Na, P, Cl, K, Sc, Ti, V, Cr, Mn, Co, Cu, and Zn. K lines and edges from such elements are observed in the X-ray spectra of supernova remnants, galaxy clusters, and accreting black holes and neutron stars, their diagnostic potential being limited by poor atomic data. We here complete the previously reported radiative datasets with new photoabsorption and photoionization cross sections for isoelectronic sequences with electron number 19<=N<=26. We also describe the access to and integrity and usability of the whole resulting atomic database. Target representations were obtained with the atomic structure code AUTOSTRUCTURE. Where possible, cross sections for ground-configuration states were computed with the Breit--Pauli R-matrix method (BPRM) in either intermediate or LS coupling including damping (radiative and Auger) effects; otherwise and more generally, they were generated in the isolated-resonance approximation with AUTOSTRUCTURE. Cross sections were computed with BPRM only for the K (N=19) and Ca (N=20) isoelectronic sequences, the latter in LS coupling. For the remaining sequences (21<=N<=26), AUTOSTRUCTURE was run in LS-coupling mode taking into account damping effects. Comparisons between these two methods for K-like ZnXII and Ca-like ZnXI show that to ensure reasonable accuracy, the LS calculations must be performed taking into account the non-fine-structure relativistic corrections. The original data structures of the BPRM and AUTOSTRUCTURE output files, namely photoabsorption and total and partial photoionization cross sections, are maintained but supplemented with files detailing the target (N_T_-electron system, where N_T_=N-1) representations and photon states (N-electron system). We conclude that because of the large target size, the photoionization of ions with N>20 involving inner-shell excitations rapidly leads to untractable BPRM calculations, and is then more effectively treated in the isolated resonance approximation with AUTOSTRUCTURE. This latter approximation by no means involves small calculations as Auger damping must be explicitly specified in the intricate decay routes.