Blanc, F., et al., Dynamic Nuclear Polarization Enhanced Natural Abundance 17O Spectroscopy. J. Am. Chem. Soc., 2013. 135(8): p. 2975-2978.
http://dx.doi.org/10.1021/ja4004377
We show that natural abundance oxygen-17 NMR of solids could be obtained in minutes at a moderate magnetic field strength by using dynamic nuclear polarization (DNP). Electron spin polarization could be transferred either directly to 17O spins or indirectly via 1H spins in inorganic oxides and hydroxides using an oxygen-free solution containing a biradical polarization agent (bTbK). The results open up a powerful method for rapidly acquiring high signal-to-noise ratio solid-state NMR spectra of 17O nuclear spins and to probe sites on or near the surface, without the need for isotope labeling.