Nuclear magnetic resonance of N-15 in the paramagnetic state of enriched uranium mononitride (U N-15)

Nuclear-magnetic-resonance (NMR) measurements were made on N-15 in the paramagnetic state of enriched (UN)-N-15. The Knight shift K and the linewidth in (UN)-N-15 were measured under similar conditions as in previous NMR measurements on (UN)-N-14, except that in (UN)-N-15 the observed dispersion lines were distorted and broadened experimentally. Although the K values in (UN)-N-15 are slightly lower than those in (UN)-N-14, their dependence on the molar susceptibility chi(M), K = K-0 +alpha chi(M), is nearly the same, with a slope alpha((UN)-N-15) = 3.8 +/- 0.4 mole/emu instead of alpha((UN)-N-14) = 4.20 +/- 0.25 mole/emu, and with similar K-0 values. The different chi(m) data in the literature and their effect on K-0 and K are attributed to variations in stoichiometry and substitutional impurities among the samples.