L i ( i=1,2,3) subshell X-ray production cross-sections and fluorescence yields for Ir, Pt, Pb and Bi

Abstract

The L i ( i=1,2,3) subshell X-ray production (XRP) cross-sections were measured for 77Ir, 78Pt, 82Pb and 83Bi following direct ionization in the L i ( i=1,2,3) subshells by the 59.54 keV γ-rays and the L 3 subshell by the Br/Rb/Sr/Y K X-rays. The photon sources consisting of an 241Am source in (i) the direct excitation mode and (ii) the secondary excitation mode together with the KBr/RbNO 3/SrCO 3 /Y secondary exciter and an Si(Li) detector were used. The L i ( i=1,2,3) subshell fluorescence yields ( ω i ) for these elements were deduced using the measured XRP cross-sections and the L i subshell photoionization cross-sections based on the Hartree–Fock–Slater model. The measured ω 1 values are found to be higher upto 50% than those based on the relativistic Dirac–Hartree–Slater (RDHS) calculations, while the ω 2 and ω 3 values exhibit good agreement. The predicted jump in the RDHS based ω 1 values from 77Ir to 78Pt due to onset of intense L 1–L 3M 4 CK transition is not observed.