The gamma-ray and conversion-electron spectra accompanying the decay of 4.0-day ${\mathrm{Pd}}^{100}$ have been studied using a lithium-drifted germanium detector, permanent-magnet spectrographs, and an orange beta-ray spectrometer. Strong transitions with indicated multipolarities have been found at $32.72 \mathrm{}(M1+E2\mathrm{})\mathrm{}$, $42.10 \mathrm{}\left(E1\mathrm{}\right)\mathrm{}$, $74.77 \mathrm{}\left(E1\mathrm{}\right)\mathrm{}$, $84.00 \mathrm{}\left(M1\mathrm{}\right)\mathrm{}$, and $126.07 \mathrm{}\left(E1\mathrm{}\right)\mathrm{}$ keV; weaker transitions have been observed at 55.82, 139.72, 151.55, and $158.77 \mathrm{}\left(E1\mathrm{}\right)\mathrm{}$ keV. The level scheme of odd-odd ${\mathrm{Rh}}^{100}$ has been elucidated, using conversion electron-$\gamma$-ray coincidence measurements. Levels in ${\mathrm{Rh}}^{100}$ are indicated at 0 (1-), 32.70 (2-), 74.79 (2+), 158.77 (1+), and 214.6 (+) keV. Delayed-coincidence events were observed between the strong 74.77- and 84.00-keV transitions, indicating a lifetime of 0.18±0.02 μsec for the 74.79-keV level in ${\mathrm{Rh}}^{100}$. It is suggested that two different proton configurations ${\left(g_{\frac{9}{2}}\right)}^5$ and ${\left(g_{\frac{9}{2}}\right)}^4{p}_{\frac{1}{2}}$ contribute to the positive- and negative-parity ${\mathrm{Rh}}^{100}$ states, respectively. Proton and neutron shell-model configurations are suggested for several levels. A $\mathrm{jj}$-coupling model is used to interpret the spins and parities of the observed levels.

• Received 27 January 1965

DOI:https://doi.org/10.1103/PhysRev.138.B1017