The spectroscopic quadrupole moments of the neutron deficient radioactive Ir isotopes ${}^{184}$Ir, ${}^{186}$I${\mathrm{r}}^{\mathit{g}}$, ${}^{186}$I${\mathrm{r}}^{\mathit{m}}$, ${}^{187}$Ir, ${}^{188}$Ir, and ${}^{189}$Ir were measured with the technique of quadrupole-interaction-resolved NMR on oriented nuclei. The ratio of quadrupole moments of the $2^{-}$ isomeric state ${}^{186}$I${\mathrm{r}}^{\mathit{m}}$ and the $5^{+}$ ground state ${}^{186}$I${\mathrm{r}}^{\mathit{g}}$ points to different nuclear deformations in these states. In addition, we present a new method for the unambiguous measurement of ground state spins.

• Received 12 June 1996

DOI:https://doi.org/10.1103/PhysRevLett.77.5016