The high spin yrast structure of ${}_{}{}^{117}{}_{}{}^{}\mathrm{I}$ has been studied with the ${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}$${+}^{94}$Mo reaction at 129 MeV. Three structural features have been identified: (i) coexisting prolate (γ=0°) and oblate (γ=-60°) collective shapes involving the π${\mathit{h}}_{11/2}$ orbital, (ii) noncollective oblate (γ=+60°) shapes associated with band termination, and (iii) a delayed ν${\mathit{h}}_{11/2}$ crossing frequency in the π[550]1/$2^{\mathrm{-}}$ yrast band.

• Received 24 June 1993

DOI:https://doi.org/10.1103/PhysRevC.48.2629