NMR Studies of Actinide Compounds: The NMR of Actinide Nuclei

In a brief recap of recent work on actinide NMR studies at JAERI, we review the direct observation of 235 U NMR which has been carried out for both UO 2 and USb 2 , as well as the estimate of T 1 ( T ) for 235 U which has been obtained from indirect (i.e., T 2 of 103 Rh) NMR studies of the Pauli paramagnet URh 3 . New data for 1/ T 1 vs T for 17 O in NpO 2 are presented and analyzed. A sizeable fraction of the observed relaxation rate is strongly field-dependent, an effect attributed to a cross-relaxation process from the 100%-abundant, I = 5/2 237 Np nuclear spins. Analysis of this relaxation component leads to quantitative estimates of T 1Np (≃40 ns) and of anomalously enhanced values of the 17 O– 237 Np nuclear spin-spin coupling. These effects as well as future prospects for actinide NMR studies are discussed.