M-Shell Fluorescence Yields of Bismuth, Lead, Gold, and Osmium

The partial $M$-shell fluorescence yields of four heavy elements (bismuth, lead, gold, and osmium) have been determined. The method employed was similar to that used for previous measurements of $L$-shell fluorescence yields. Thin foils of the materials to be studied were exposed to x rays or $\gamma$ rays which could create vacancies in the $L$ shells of the irradiated materials. The $M$-shell fluorescence yields were then determined by measuring the coincidence rate between the $L$ and the $M$ x rays observed following the $M$-shell ionization. It is shown that for the method used here the $M$-shell fluorescence yield determined is predominantly a combination of the fluorescence yields of the $M_{\mathrm{IV}}$ and the $M_{\mathrm{V}}$ subshells. The following values were obtained: bismuth, 0.037±0.007; lead, 0.032±0.006; gold, 0.030±0.006; and osmium, 0.016±0.003.