Experimental investigation of high-spin states in Nb91

High-spin states of ⁹¹Nb have been investigated using the heavy-ion fusion-evaporation reaction ⁶⁵Cu(³⁰Si, $2p2n)$ at a beam energy of 120 MeV. States of ⁹¹Nb up to excitation energy ≈12 MeV and spin 41/24pt0ex have been observed with the addition of thirteen new γ-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 ⁶⁸Ni 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 1g9/2 orbital, an important role of neutron excitation in the 1g7/2 orbital in generating the high-spin states in ⁹¹Nb has been identified.