Plutonium-239 yields to nuclear magnetic resonance. An appropriately tuned RF wave will excite a nucleus whose energy levels have been split by an externally applied magnetic field; that’s the basis for nuclear magnetic resonance (NMR). The precise excitation frequency gives information about the nucleus’s local magnetic environment, which perturbs the field experienced by the nucleus. For more than 50 years, 239Pu stymied efforts to probe it with NMR, but Hiroshi Yasuoka and colleagues at the Japan Atomic Energy Agency and Los Alamos National Laboratory have now coaxed a signal from the iconic nucleus. The group had to overcome two principal difficulties. First, the hyperfine interaction between electron and nuclear spins is unusually strong in 239Pu, which means the NMR signal decays extremely quickly. Second, the gyromagnetic ratio γ of 239Pu, which relates external field and resonance frequency, was poorly known; the Yasuoka team had only a rough...

You do not currently have access to this content.