Prompt and delayed $\gamma$ rays from ${}^{191,193}\mathrm{Bi}$ have been identified using the recoil-decay tagging, isomer tagging, and recoil gating techniques, resulting in extensive level schemes for both nuclei. Excitation energies of the isomeric $13∕2^{+}$ states have been established and oblate strongly coupled bands built on them have been observed. The nearly spherical $9∕2^{-}$ ground-state bands appear to be crossed by more oblate-deformed low-lying structures. The properties of the bands feeding the $1∕2^{+}$ intruder states indicate some structural change between ${}^{193}\mathrm{Bi}$ and ${}^{191}\mathrm{Bi}$. The deformation associated with each of these states has been extracted from total Routhian surface calculations which also reveal the development of prolate minima with decreasing neutron number. $B\left(M1\right)∕B\left(E2\right)$ ratios have been measured for the observed strongly coupled bands in order to resolve the intrinsic excitations. The observed quasiparticle structures in ${}^{193}\mathrm{Bi}$ and high-spin isomers both in ${}^{193}\mathrm{Bi}$ and ${}^{191}\mathrm{Bi}$ are interpreted based on the coupling of the odd proton to the even-even $\mathrm{Pb}$ core.

• Received 2 December 2003

DOI:https://doi.org/10.1103/PhysRevC.69.064326