We report on new or more precise half-lives, $\beta$-decay endpoint energies, and $\beta$-delayed proton emission branching ratios of ${}^{91}\mathrm{Pd}$, ${}^{95}\mathrm{Cd}$, ${}^{97}\mathrm{In}$, and ${}^{99}\mathrm{Sn}$. The measured values are consistent with known mirror transitions in lighter $T_z=-1/2$ nuclei, shell-model calculations, and various mass models. In addition to the $\beta$-decaying $(9/2^{+})$ ground state, circumstantial evidence for a short-lived, proton-emitting isomer with spin $(1/2^{-})$ was found in ${}^{97}\mathrm{In}$. Based on the experimental data, a semiempirical theory on proton emission, and shell-model calculations, the proton separation energy of the ${}^{97}\mathrm{In}$ ground state was determined to be $-0.10\pm 0.19$ MeV. The existence of the short-lived, proton-unstable $(1/2^{-})$ isomer in ${}^{97}\mathrm{In}$ establishes ${}^{96}\mathrm{Cd}$ as an $rp$-process waiting point.

• Received 7 June 2017
• Revised 11 January 2018

DOI:https://doi.org/10.1103/PhysRevC.97.051301