PerspectiveChemistry

NMR Tools for Determining the Structure of Plutonium Materials

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Science  18 May 2012:
Vol. 336, Issue 6083, pp. 811-812
DOI: 10.1126/science.1222927

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Summary

Nuclear magnetic resonance (NMR) is an extremely powerful method for determining molecular structures in a rapid and nondestructive way. The technique is typically applied to nuclei that have a spin quantum number of ½, which fortunately includes many of the nuclei in organic molecules, such as 1H, 13C, and 31P. NMR spectroscopy yields different signals for specific nuclei—“chemical shifts”—because different local arrangements of nearby nuclei and electronic bonds perturb the local magnetic field of a nucleus. The patterns of chemical shifts can be determined for compounds of known structure, and structures of unknown compounds can often be ascertained on the basis of the number and location of signals in the spectrum; their relative intensity of signal reflects the number of nuclei experiencing that specific chemical environment. The last of the heavy nuclei with I = ½ for which the NMR spectrum was undetermined has been 239Pu, despite decades of effort, but on page 901 of this issue, Yasuoka et al. (1) report a technique for 239Pu NMR.