Figure 1

Neutron single-particle energies for the odd-mass Zr isotopes, expressed as the excitation energies (top), where positive (negative) values indicate particle (hole) states, and relative to that of the $\nu d_{5/2}$ orbital (bottom). The values for $A=91–97$ are taken from Ref. [2], and those for ${}^{99}\mathrm{Zr}$ are extracted from the IBFM calculations of Refs. [8, 9] (open symbols), and Ref. [1] (filled symbols).