~(239)Pu-distant ENDOR in Pu(III) sulphate; Pu_2(SO_4)_3.7H_2O : A ease of large pseudo-nuclear Zccman Effect

摘要

NMR of Pu~(239) has not been reported so far presumably due to problems associated with nuclides of low magnetic moment. A possible alternative way to get information similar to that obtainable by NMR is to look for distant ENDGR, using a suitable paramagnetic center, in plutonium compounds. The EPR spectra of title compound at room temperature, in the initial stages (dose of approx 12 kGy) showed presence of SO_4 ( g// = 2.0402, gx = 2.0033) and SO_3~-(g_(iso) = 1.9976 ) radicals along with signal from silver impurity. However, on long irradiation (dose ~ 600 kGy) only an intense signal of SO_3~- with g// -2.0013 and g =2.0002 having DELTA H = 3.0 G was observed. An ENDOR spectrum of self-irradiated sample was recorded by saturating the SO3" signal. The room temperature ENDOR consisted of two relatively intense transitions, one at 2.9 MHz and the other at 14.5 MHz respectively in addition to a weak one around 1.35 MHz with line shape typical of a parallel component (Fig. 1). The signal at 14.5 MHz is assigned to free Larmor precession of 1H~1.