High-spin states of ${}^{91}\mathrm{Nb}$ have been investigated using the heavy-ion fusion-evaporation reaction ${}^{65}\mathrm{Cu}({}^{30}\mathrm{Si}$, $2p2n)$ at a beam energy of 120 MeV. States of ${}^{91}\mathrm{Nb}$ up to excitation energy $\approx 12$ MeV and spin $41/2\hslash$ have been observed with the addition of thirteen new $\gamma$-ray transitions to the proposed level scheme. Structures of positive- and negative-parity states up to the highest observed spin have been interpreted with shell-model calculations using the GWBXG interaction and a ${}^{68}\mathrm{Ni}$ core. High-spin states in this nucleus are dominated by the configurations involving both proton- and neutron-core excited structures. Owing to the presence of one valence proton in the $1g_{9/2}$ orbital, an important role of neutron excitation in the $1g_{7/2}$ orbital in generating the high-spin states in ${}^{91}\mathrm{Nb}$ has been identified.

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• Electromagnetic transitions
• High spin states
• Nuclear structure & decays
• Transfer reactions
• 90 ≤ A ≤ 149