The high-spin states of near-spherical nuclei can be constructed by coupling the angular momentums of openshell nucleons. The maximum-spin state of valence space is made by aligning the angular momentums of all valenceFig. 1 The revised level scheme of 91Y deduced from thepresent work.nucleons. Beyond that, the higher-spin states can begenerated by breaking the shell closures. Many studieshave been made about such excitation process of nucleiaround the quasi-doubly magic nucleus[1??4].