Static quadrupole moments ($Q$) of $8^{+}$ isomers in ${}_{}{}^{88,90}{}_{}{}^{}\mathrm{Zr}$ and the ${\frac{21}{2}}^{+}$ isomer in ${}_{}{}^{91}{}_{}{}^{}\mathrm{Zr}$, as well as $Q$ ratios of $8^{+}$ isomers in ${}_{}{}^{90,92,94}{}_{}{}^{}\mathrm{Mo}$, have been measured with the time-differential perturbed-angular-distribution technique. The isomers were excited by pulsed heavy-ion beams and recoil implanted into single crystals of Zr in which their quadrupole precession was observed. Our results, the first such data for high-spin isomers in the $g_{\frac{9}{2}}$ shell, yield large $E2\mathrm{}$ effective charges for the $g_{\frac{9}{2}}$ proton and the $g_{\frac{9}{2}}$ neutron. The systematics of these charges are comprehensively explained by particle-vibration coupling and the blocking effect.

• Received 26 December 1984

DOI:https://doi.org/10.1103/PhysRevLett.54.2592