Measurements ofL2−andL3-Subshell Fluorescence Yields in Heavy Elements

Measurements have been made of $L_2-$ and $L_3$-subshell x-ray fluorescence yields, ${\omega }_2$ and ${\omega }_3$, for elements $Z=71-83, 90, \mathrm{and} 92$. The method consisted of photoexciting $K$-shell vacancies in thin metal or oxide samples; observing with a Ge(Li) spectrometer the $K{\alpha }_1$ and $K{\alpha }_2$ x rays emitted as the $K$ vacancies were filled by electrons from $L_3$ or $L_2$ subshells; and counting, with a detector of calculated efficiency, the $L$ x rays (unresolved) which signify radiative filling of those vacancies. The directly measured quantities were ${\omega }_3$ and ${\nu }_2={\omega }_2+f_{23}{\omega }_3$. The quantity $f_{23}$ was taken as 0.13±0.13 to estimate ${\omega }_2$. The estimated precision (2 standard deviations) varies between 8 and 15%. The ${\nu }_2$ data agree with previous work. The ${\omega }_2$ values lie above most previous results. The ${\omega }_3$ values substantiate other recent experimental work, but exceed earlier estimates. The yields increase monotonically with increasing atomic number, within the limit of precision. Results with an alternative experimental arrangement indicate a small angular correlation in $K-L_3-M$, $N$ x-ray cascades.