L 1–L 3 Coster–Kronig yield for Ir, Pt and Bi

Abstract

The L 1–L 3 Coster–Kronig yield, f 13, for 77Ir, 78Pt and 83Bi was determined using measured intensities of the Lα X-rays following photoionisation in the L i ( i=1,2,3) subshells in different proportions by the 59.5 keV γ-rays and the characteristic K X-rays of the Br/Sr/Y elements. The measurements involved an Si(Li) detector and photon sources consisting of an 241Am source used in (i) the direct excitation mode and (ii) the secondary excitation mode together with the KBr, SrCO 3 and Y secondary exciters. The measured values of the f 13 yield are 0.467±0.025, 0.527±0.027 and 0.620±0.025 for 77Ir, 78Pt and 83Bi, respectively. These values are found to be substantially smaller than those based on the relativistic Dirac–Hartree–Slater calculations.