Dr. Frédéric Blanc ，Department of Chemistry and Stephenson Institute for Renewable Energy, University of Liverpool
Conference Room of Basic Energy Science Building
July 1, 2015 (Wednesday) 9:00am
Abstract
Dynamic nuclear polarization (DNP) is an extremely powerful approach for signal enhancement in solid-state NMR1 by increasing the sensitivity by multiple orders of magnitude, and is being used to elucidate the atomic scale structures of a wide range of materials.2–5 We will present how this could be used to quickly detect the NMR signals of insensitive nuclei such as the ones with low natural abundance (e.g. 17O, 0.067 %) or with small magnetic moments (e.g. 89Y).
Natural abundance 17O NMR of solids could be obtained in minutes only at 9.4 T by using DNP at low temperature under static and MAS conditions. Electron spin polarization could be transferred either directly to 17O spins or indirectly via 1H in oxides and hydroxides using an oxygen-free 1,1,2,2-tetracholoroethane solution containing a biradical polarization agent.6 The results open up a powerful method for rapidly acquiring high signal-to-noise ratio solid-state NMR spectra of 17O and to probe sites on or near the surface, without the need for isotope labeling.
Solid-state NMR spectra of nuclei with low gyromagnetic ratio such as 89Y can be acquired fairly quickly with cross polarization and DNP at 9.4 T.7 The detection of the 89Y NMR signals from hydrated yttrium doped zirconates,8 in combination with DFT calculations, allows the local yttrium (and proton) environments present in these important protonic conductors to be detected.
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Blanc, F. et al. J. Am. Chem. Soc. 2013, 135, 15290. (4) Zhe Ni, Q. et al. Acc. Chem. Res. 2013, 46, 1933.
(5) Rossini, A. J. et al. L. Acc. Chem. Res. 2013, 46, 1942. (6) Blanc, F. et al. J. Am. Chem. Soc. 2013, 135,
2975. (7) Blanc, F. et al. J. Phys. Chem. Lett. 2014, 5, 2431. (8) Yamazaki, Y. et al. Nat. Mat. 2013, 12,
647.
Ying Shi （9128）