High-spin excited states in the very neutron-rich nucleus ${}^{114}\mathrm{Rh}$ have been studied by examining the prompt $\gamma$ rays emitted in the spontaneous fission of ${}^{252}\mathrm{Cf}$ with the Gammasphere detector array. A high-spin level scheme of ${}^{114}\mathrm{Rh}$ has been established for the first time with 13 new levels. The level scheme is proposed to be built on a $7^{-}$ state. The existence of a relatively large signature splitting and an yrare band show features which may indicate triaxial deformation. The phenomenon of signature inversion has been observed in ${}^{114}\mathrm{Rh}$ at $I=12\hspace{0.5em}\hslash$. The observed signature inversion of ${}^{114}\mathrm{Rh}$ is interpreted successfully in terms of the triaxial projected shell model. Theoretical calculations suggest that the negative-parity, yrast band of ${}^{114}\mathrm{Rh}$ has the two-quasi-particle configuration of $\pi g_{9/2}\otimes \nu h_{11/2}$, consistent with the systematics of odd-odd Rh isotopes. The signature inversion at spin $12\hspace{0.5em}\hslash$ may be attributed to the change of rotational mode, from quasi-particle aligned rotation at low spins to collective rotation at high spins.

• Received 22 February 2011

DOI:https://doi.org/10.1103/PhysRevC.83.064310