M2Isomerism inRb83and High-Resolution Spectroscopic Investigations of the Decay ofSr83

The photon spectrum accompanying the electron-capture decay of ${}_{}{}^{83}{}_{}{}^{}\mathrm{Sr}$ has been studied with highresolution Ge(Li) spectrometers in singles and coincidence configurations. The positron and internal-conversion-electron spectra were investigated with the MSU "orange" and $\pi \sqrt{2}$ iron-free electron spectrometers. Sixty transitions were identified. Excited states have been placed in ${}_{}{}^{83}{}_{}{}^{}\mathrm{Rb}$ at 5.0, 42.3, 295.2, 389.2, 423.5, 736.8, 804.8, 994.2, 1043.7, 1053.7, 1103.0, 1202.0, 1242.6, 1273.1, 1324.6, 1653.1, 1756.9, 1783.5, 1916.7, 1952.2, 2014.8, 2090.0, 2147.8, and 2179.3 keV. Internal-conversion coefficients, $log\mathrm{ft}$, and $\gamma$-ray branching ratios have been used to place limits upon the spins and parities of the excited states. An isomeric $M2\mathrm{}$ transition of 42.3 keV has been identified. The ground-state spin and parity of ${}_{}{}^{83}{}_{}{}^{}\mathrm{Sr}$ have been shown to be ${\frac{7}{2}}^{+}$, which are the same as for all other known 45-neutron nuclei.