Influence of the νg9/2 orbital on level structures of neutron-rich Mn61,6236,37

Level structures in Mn61,62_36,37 were studied with Gammasphere in the reaction of a 430-MeV Ni64 beam and a thick U238 target. The newly identified levels decrease in excitation energy compared to the analogous structures in the lighter Mn isotopes and behave similarly to states in the corresponding Fe isotones that involve g_9/2 neutron excitations. This behavior illustrates the importance of the inclusion of the νg_9/2 orbital in any realistic shell-model calculations in this region.