The low temperature electric quadrupole orientation of¹⁸⁴Ir and¹⁸⁵Ir in rhenium

Abstract

The half-lives of¹⁸⁴Ir,¹⁸⁵Ir and¹⁸⁶Ir have been determined to be 3.14(2) h, 14.4(1) h and 16.64(3) h, respectively. The quadrupole frequenciesv _Q = e²qQ_s/h of¹⁸⁴Ir and¹⁸⁵Ir in rhenium single crystal have been determined to be Q_s(¹⁸⁴Ir) = + 2.0(3) b MHz and Q_s(¹⁸⁵Ir) = +2.0(3) b MHz. Adopting the value of −3.6(2)×10¹⁷ V·cm⁻² for the electric field gradient eq at T=0 K, the values of the ground-state spectroscopic quadrupole moments of these isotopes are determined to be Q_s(¹⁸⁴Ir)=+2.0(3) b and Q_s(¹⁸⁵Ir)=−2.5(3) b. The¹⁸⁵Ir moment is only consistent with the ground state Nilsson configuration$I^\pi K = \tfrac{5}{2} - \tfrac{1}{2}$, the¹⁸⁴Ir moment is consistent with K≥4 with a predominant K=4 component, in disagreement with K=0,1 found for¹⁸⁶Ir. Our analysis differs in detail from the recent nuclear orientation study by Hagn et al.[1].