Collinear laser spectroscopy has been performed on the 3079Zn49
isotope at ISOLDE-CERN. The existence of a long-lived isomer with a few hundred
milliseconds half-life was confirmed, and the nuclear spins and moments of the
ground and isomeric states in 79Zn as well as the isomer shift were
measured. From the observed hyperfine structures, spins I=9/2 and I=1/2
are firmly assigned to the ground and isomeric states. The magnetic moment
μ (79Zn) = −1.1866(10) μN, confirms the spin-parity
9/2+ with a νg9/2−1 shell-model configuration, in excellent
agreement with the prediction from large scale shell-model theories. The
magnetic moment μ (79mZn) = −1.0180(12) μN supports a
positive parity for the isomer, with a wave function dominated by a 2h-1p
neutron excitation across the N=50 shell gap. The large isomer shift
reveals an increase of the intruder isomer mean square charge radius with
respect to that of the ground state: δ⟨rc2⟩79,79m
= +0.204(6) fm2, providing first evidence of shape coexistence.Comment: 5 pages, 4 figures, 1 table, Accepeted by Phys. Rev. Lett. (2016