Photoionization of Cl-like Ni XII using relativistic R-matrix close-coupling method

Abstract

In this study, photoionization (PI) of nickel ions Ni XII is performed using the relativistic close-coupling Breit–Pauli R-matrix method. The calculation includes 47 lowest target states of Ni XIII, which have been evaluated using a sophisticated configuration interaction technique. Results for the PI of the ground state 3s23p5 (2[Formula: see text]) and first excited state 3s23p5 (2[Formula: see text]) are provided. The PI of this Cl-like ion is characterized by multiple Rydberg series of autoionizing resonances converging to various ionic states of Ni XIII. Our background cross section agrees well with that obtained using the Los Almos National Laboratory PI code. The resonance energy levels and widths of the Rydberg series are presented using the Quigley and Berrington approach. We believe that our results will be useful for astrophysical plasma research.