L i ( i = 1, 2, 3) sub‐shell fluorescence yields for 79 Au, 80 Hg and 81 Tl

The L i ( i = 1, 2, 3) sub‐shell x‐ray fluorescence yields (ω i ) for 79 Au, 80 Hg and 81 Tl were deduced from the measured cross‐sections for the L i ( i = 1, 2, 3) sub‐shell x‐rays following ionization by 59.54 keV γ‐rays ( B   L   1< E inc < B K ) and for the L 3 sub‐shell x‐rays following ionization by Rb K x‐rays ( B   L   3< E Kα < B   L   2, B   L   1 /L   2< E Kβ < B K ), where B   K/L   iis the K shell/L i sub‐shell ionization threshold of the target element. An energy‐dispersive x‐ray fluorescence setup, involving photon sources consisting of a 241 Am annular source in the direct and secondary excitation modes along with RbCl secondary exciter and an Si(Li) detector, was used for the measurements. The measured ω 2 and ω 3 values exhibit good agreement with those based on the relativistic Dirac–Hartree–Slater (RDHS) calculations, while the ω 1 values are found to be higher by ∼25%. The present data indicate that the L 1 –L 3 Coster–Kronig yield f 13 based on the RDHS calculations are overestimated. Copyright © 2004 John Wiley & Sons, Ltd.