L-Shell Fluorescence Yields of Pt, Tl, and Pb

Partial $L$-shell fluorescence yields for three heavy elements have been measured using an x-ray coincidence counting method. Vacancies in the $K$ shell of the atom are produced either by $K$-electron capture or internal conversion of a nuclear gamma ray in the $K$ shell. The coincidence rate between the $K$ and $L$ x rays observed after the creation of the $K$ vacancy determines the partial fluorescence yield, ${\omega }_{\mathrm{KL}}$. This quantity is defined as the fluorescence yield of those vacancies in the $L$ shell created by $K_{{\alpha }_1}$ and $K_{{\alpha }_2}$ x-ray emission. In some cases, it was also possible to determine the partial fluorescence yield, ${\omega }_{\mathrm{LL}}$ of the $L$ shell following $L$-electron capture. The results obtained are in reasonable agreement with previous measurements. The relationship between ${\omega }_{\mathrm{KL}}$, ${\omega }_{\mathrm{LL}}$, and the fluorescence yields of individual $L$ subshells is discussed.