L-vacancy decay in heavy elements (72≤Z≤82) by the synchrotron photoionization method

Abstract

Employing the novel synchrotron photoionization method, the Coster-Kronig decay yields $f_{12}$, $f_{13}$, and $f_{23}$ as well as the ratios of radiative yields ${\omega }_1$/${\omega }_3$ and ${\omega }_2$/${\omega }_3$ have been measured for a series of neighboring heavy elements with a typical uncertainty of ±0.01 and ±0.03, respectively. The data for $f_{23}$ and ${\omega }_2$/${\omega }_3$ are compared to published experimental data obtained with the Kα-Lα coincidence method that have small uncertainty; reasonable agreement is found. In contrast, our $f_{12}$ values are considerably smaller (factor of 2–3) than published experimental values obtained by various techniques; this result indicates systematic problems of these techniques. Using the well-known fluorescence yield ${\omega }_3$ and calculated absolute transition rates of the radiative decay, we have derived absolute transition rates of the nonradiative decay from our experimental data. Comparison of the observed values with theoretical transition rates shows that the theory substantially overestimates the rates of such nonradiative transition channels in which the excess energy carried away by the emitted electron is substantially smaller than the energy of the initial vacancy state.