Rotational states have been identified in ${}_{51}{}^{111}{}_{}{}^{}\mathrm{Sb}$ for the first time. Three decoupled (ΔI=2) bands extending to over 1 MeV in rotational frequency have been observed. At the highest frequencies, the ${\mathit{scrJ}}^{\mathrm{}\left(2\right)\mathrm{}}$ moments of inertia for these three bands are seen to decrease steadily to unexpectedly low values; this is interpreted as evidence for a novel form of band termination. One of these bands is interpreted as being based on the π${\mathit{h}}_{11/2}$ orbital coupled to a deformed [(π${\mathit{g}}_{9/2}$${)}^{\mathrm{-}2}$⊗(π${\mathit{g}}_{7/2}$)${]}_{0+}$ state of the ${}_{50}{}^{110}{}_{}{}^{}\mathrm{Sn}$ core. The interaction strength for the alignment of a pair of ${\mathit{h}}_{11/2}$ neutrons has been extracted and compared with calculations. Two possible quasiparticle configurations are discussed for the other decoupled bands. Two strongly coupled (ΔI=1) bands have been identified and both shown to involve the [(π${\mathit{g}}_{9/2}$${)}^{\mathrm{-}1}$⊗(π${\mathit{g}}_{7/2}$${)}^2$] configuration. A large number of spherical states have also been observed, which can be explained on the basis of valence protons coupled to spherical states in the ${}_{}{}^{110}{}_{}{}^{}\mathrm{Sn}$ core.

• Received 4 April 1994

DOI:https://doi.org/10.1103/PhysRevC.50.1819