The excited states in the transitional nucleus ${}^{131}\mathrm{Xe}$ have been populated by using $\alpha$-induced fusion-evaporation reaction and the de-exciting $\gamma$ rays were detected with the Compton suppressed clover detector setup of the Indian National Gamma Array coupled to digital data acquisition system. The existing level structure of ${}^{131}\mathrm{Xe}$ has been significantly extended with the observation and placement of 72 new $\gamma$-ray transitions. The use of light-ion ($\alpha$) beam helped to identify several new band structures in ${}^{131}\mathrm{Xe}$ with different quasiparticle (qp) configurations. The multipolarities of the observed $\gamma$ rays have been determined on the basis of the directional correlation from oriented states ratio and polarization asymmetry measurements. The yrast negative-parity band has been confirmed up to ${35/2}^{-}$ spin and the highly nonyrast signature partner of this band has been identified for the first time. The positive-parity band, based on the ${3/2}^{+}$ ground state, has been extended up to ${23/2}^{+}$ with the observation of a signature inversion, which signifies a pair of particle alignment around the spin of 15/2 $\hslash$. A dipole band, consisting of $M1$ transitions has been identified and assigned a 5-qp configuration. A new band structure built on a 3-qp ${23/2}^{+}$ state has been observed with a large signature splitting. A comparison in the isotopic and isotonic chains reveals the transitional nature of the $N=77$ nuclei. Total Routhian surface calculations have been performed to understand the structure of ${}^{131}\mathrm{Xe}$ associated with different configurations.

• Received 3 October 2019
• Revised 6 January 2020
• Accepted 4 March 2020

DOI:https://doi.org/10.1103/PhysRevC.101.044306