State‐selected photo‐recombination cross sections of H‐like ions in the KLL resonant energy range

Abstract

We theoretically study the state‐selected photo‐recombination process of highly charged ions using the close‐coupling approximation and the full relativistic Dirac R‐matrix method combined with the Dirac Atomic R‐matrix Codes (DARC). Focusing on the interference between the direct and indirect processes and the relativistic effects on the spin‐orbit splitting, we calculate the total and partial photo‐recombination cross sections of the H‐like Ne, Cl, Fe, and Kr ions. The energies of the incident electrons are considered as in the resonant regions, in which the initial state is the ground state of the H‐like ions and the recombined states includes the ground state and six lower excited states , and of the He‐like ions. We utilize the multi‐configuration Dirac‐Fock method to calculate the target state wavefunctions, transition energies, and transition probabilities of both the one‐electron one‐photon (OEOP) and two‐electron one‐photon (TEOP) transitions from the resonant captured states to the recombined states. By analyzing the calculated atomic data, we identify all resonant peaks in each partial photo‐recombination process, and our results agree well with the available results in literature. Our study reveals a significant interference effect in the photo‐recombination cross sections, especially in the partial cross sections. Moreover, we present the eigenphase as a function of the electron energy for each partial photo‐recombination channel.