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Abstract

Magnetic and quadrupole moments of the 7/2⁺ ground state in ¹³³Sb and the (7⁻) isomer in ¹³⁴Sb have been measured by collinear laser spectroscopy to investigate the single-particle behavior above the doubly magic nucleus 132Sn. The comparison of experimental data of the 7/2⁺ states in ¹³³Sb and neighboring N=82 isotones to shell-model calculations reveals the sensitivity of magnetic moments to the splitting of the spin-orbit partners π0g_9/2 and π0g_7/2 across the proton shell closure at Z=50. In contrast, quadrupole moments of the N=82 isotones are insensitive to cross-shell excitations, but require the full proton model space from Z=50 to 82 for their accurate description. In fact, the linear trend of the quadrupole moment follows approximately the expectation of the seniority scheme when filling the π0g_7/2 orbital. As far as the isomer in ¹³⁴Sb is concerned, its electromagnetic moments can be perfectly described by the additivity rule employing the moments of ¹³³Sb and ¹³³Sn, respectively. These findings agree with shell-model calculations and thus confirm the weak coupling between the valence proton and neutron in ¹³⁴Sb.