Line-shape effects on the determination of Coster-Kronig probabilities using Si(Li) x-ray detectors.

Abstract

The great majority of measured values of the Coster-Kronig probability ${\mathit{f}}_{23}$ derive from x-ray coincidence experiments using radionuclide sources or from synchrotron-radiation excitation of thin foils. Very little attention has been paid in published work to the role of line-shape effects and satellites in the x-ray spectra that are obtained. It is shown that this neglect can influence ${\mathit{f}}_{23}$ values derived from such measurements. This may explain in part the well-established trends for measured ${\mathit{f}}_{23}$ values to fall below the theoretical predictions for elements with atomic number Z90 and to fall above when Z>92. In elemental analysis techniques based upon x-ray emission spectroscopy, where a database of atomic parameters such as Coster-Kronig probabilities is used, the same approximations are made in treating the spectra. Until a more sophisticated approach to spectrum reduction is developed, it may be preferable in this context to use ``nominal'' Coster-Kronig probabilities derived from experiment in preference to theoretical values.