Measurements of M-shell fluorescence yields and Coster-Kronig transition probabilities for Bi and Th employing synchrotron radiation induced selective photoionization

Abstract

In the present work, the M-shell fluorescence yields (ω3, ω4 and ω5) and Coster-Kronig (CK) transition probabilities (f45, f34, f35, f23, f24, f25) have been determined for Bi (Z=83) and Th (Z=90) using synchrotron radiation energies tuned across the Mi (i = 1-5) sub-shell absorption edge energies ranging 2.5 keV -5.2 keV. For both elements, two sets of fluorescence yields and Coster-Kronig transition probabilities were evaluated experimentally by employing the M-shell photoionization cross sections (PCS) based on the non-relativistic Hartree-Fock-Slater (NHFS) model tabulated by Scofield and the self-consistent Dirac-Hartree-Fock (DHF) model tabulated by Chantler. The present measured ωi and fij values have been compared with two sets of theoretical values based on the non-relativistic Hartree-Slater (NRHS) calculations employing the Hermann-Skillman potential reported by McGuire (1972) and the Dirac-Hartree-Slater (DHS) model predictions reported by Chauhan and Puri (2008) to assess the validity of theoretical approaches. The present work provides new experimental benchmarks for the M-shell fluorescence yields and Coster-Kronig transition probabilities, addressing existing gaps in atomic databases.