239Pu

Observation of ²³⁹Pu Nuclear Magnetic Resonance

H. Yasuoka et al.

doi: 10.1126/science.1220801

In principle, the spin-½ plutonium-239 (²³⁹Pu) nucleus should be active in nuclear magnetic resonance spectroscopy. However, its signal has eluded detection for the past 50 years. Here, we report observation of a ²³⁹Pu resonance from a solid sample of plutonium dioxide (PuO2) subjected to a wide scan of external magnetic field values (3 to 8 tesla) at a temperature of 4 kelvin. By mapping the external field dependence of the measured resonance frequency, we determined the nuclear gyromagnetic ratio ²³⁹γγ_n(PuO2)/2π to be 2.856&plusm;0.001 megahertz per tesla (MHz/T). Assuming a free-ion value for the Pu⁴⁺ hyperfine coupling constant, we estimated a bare ²³⁹γγ_n/2π value of ~2.29 MHz/T, corresponding to a nuclear magnetic moment of μ_n ≈ 0.15 μμ_N (where μ_N is the nuclear magneton).