A study has been made of $\gamma$-ray deexcitations following the $\beta$ decays of ${}_{}{}^{89}{}_{}{}^{}\mathrm{Kr}$ and ${}_{}{}^{89}{}_{}{}^{}\mathrm{Rb}$. The activities were produced from the TRISTAN on-line isotope-separator system. Measurements of $\gamma$-ray energies and intensities were made using Ge(Li) detectors. Level schemes have been constructed for ${}_{}{}^{89}{}_{}{}^{}\mathrm{Rb}$ and ${}_{}{}^{89}{}_{}{}^{}\mathrm{Sr}$ with the aid of $\gamma -\gamma$ coincidence information, and $\beta$ branching was determined from equilibrium data and $\gamma$-intensity balances. The excited levels of ${}_{}{}^{89}{}_{}{}^{}\mathrm{Sr}$ appear to be explained by single-particle states and the coupling of single-particle states to the vibration states of ${}_{}{}^{88}{}_{}{}^{}\mathrm{Sr}$. The ${}_{}{}^{89}{}_{}{}^{}\mathrm{Rb}$ nucleus is shown to have a complex level scheme and will require further studies to clarify the picture of its nuclear structure.

• Received 21 August 1972

DOI:https://doi.org/10.1103/PhysRevC.7.222