Internal-Conversion Studies withSn119mandSn117m

Measurements were made with a magnetic spectrometer of the internal conversion-electron lines from the $M4\mathrm{}$ and $M1\mathrm{}\left(E2\mathrm{}\right)\mathrm{}$ transitions which occur in cascade in the decay of ${\mathrm{Sn}}^{117m}$ and ${\mathrm{Sn}}^{119m}$. In the case of ${\mathrm{Sn}}^{117m}$, the transition energies are 156.0±0.1 keV ($M4\mathrm{}$) and 158.6±0.1 keV [$M1\mathrm{}\left(E2\mathrm{}\right)\mathrm{}$]; ${\alpha }_K\mathrm{}\left(158.6\right)\mathrm{}$ was found to be 0.1373±0.0030. ${\mathrm{Sn}}^{117m}$ is shown to be a convenient reference standard for conversion-coefficient measurements, and working values of the "coefficient" for several kinds of measurement are given. In the case of ${\mathrm{Sn}}^{119\mathit{m}}$, the energies are 65.66±0.01 keV ($M4\mathrm{}$) and 23.875±0.010 keV [$M1\mathrm{}\left(E2\mathrm{}\right)\mathrm{}$]. Comparisons are made of measured subshell intensities with theoretical values, including those of Hager and Seltzer for the $M$ subshells; and upper limits are set for the amounts of $E2\mathrm{}$ admixture in the two $M1\mathrm{}$ transitions. For the 23.875-keV $M1\mathrm{}$ transition, the $L_1:M_1:N_1$ conversion ratios observed agree with the ratios of the electron densities near the nucleus of the bound $2s$, $3s$, and $4s$ electrons, in accord with the results of Drell and of Church and Monahan.