Single and double K-shell resonant photoionization and Auger decay of 1s → 2p excited states of O⁺–O⁴⁺

Abstract

In this work, single and double photoionization cross sections in the vicinity of 1s → 2p resonances are investigated theoretically for quantum states belonging to the ground and first excited configurations of O + -O 4+ . R-matrix method has been employed to obtain the single ionization cross section, whereas the double ionization cross sections are obtained by the branching ratios of the direct double Auger decay to the total Auger decay. By analyzing possible double ionization pathways, we conclude that the double photoionization originates predominately from the direct double Auger decay of the K-shell resonant states. Our theoretical work diagnosed the population fraction of the quantum state prepared in a recent experiment and successfully interpreted the experimental observations on both single and double photoionization cross sections.

Effects of single-photon double photoionization and direct double Auger decay on K-shell ionization kinetics of Ar atoms interacting with XFEL pulses

“…Both the SPDP cross-sections and DDAD rates required in the rate equation are calculated according to the separation of KO and SO mechanisms. The details of such a separation can be found in references [31,[40][41][42][43]] and here we only give an outline. The SPDP cross-section for a transition from an initial state i to a final state f at a photon energy E 0 reads…”

Large-scale Multiconfiguration Dirac–Hartree–Fock Calculations for Astrophysics: C-like Ions from O iii to Mg vii

“…In the past decades, there were many atomic structure calculations involving low-lying states of the n = 2 and n = 3 configurations for C-like ions from O III to Mg VII (Fawcett 1987; Bhatia & Doschek 1993, 1995Zhang & Sampson 1996;Aggarwal et al 1997;Aggarwal & Keenan 1999;Aggarwal et al 2001;Tachiev & Froese Fischer 2001;Froese Fischer & Tachiev 2004;Gu 2005;Safronova et al 2006;Jönsson & Bieroń 2010;Jönsson et al 2011;Liu et al 2013;Zeng et al 2017;Sun et al 2018Sun et al , 2020. For a review of scattering calculations, see the recent paper by Mao et al (2020).…”