The low temperature electric quadrupole orientation of 184Ir and 185Ir in rhenium

The half-lives of 184Ir, 185Ir and 186Ir have been determined to be 3.14(2) h, 14.4(1) h and 16.64(3) h, respectively. The quadrupole frequencies of 184Ir and 185Ir in rhenium single crystal have been determined to be -175(26) MHz and 219(20) MHz respectively. Adopting the value of -3.6(2) x 1017 V.cm-2 for the electric field gradient at T = 0 K, the values of the ground-state spectroscopic quadrupole moments of these isotopes are determined to be +2.0(3) b and -2.5(3) b respectively. The 185Ir moment is only consistent with the ground state Nilsson configuration Isup(π)K=5/2-1/2, the 184Ir moment is consistent with K>=4 with a predominant K = 4 component, in disagreement with K = 0, 1 found for 186Ir. (Auth.)