U.S.-China Cooperative Research (Chemistry): Dynamic Nuclear Polarization in Carbonaceous Solids

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This is a two year collaborative project between Gary Maciel of Colorado State University and Ye Chaohui of the Wuhan Institute of Physics, Chinese Academy of Sciences. It is sponsored jointly by NSF and the Chinese Academy of Sciences. Research will focus on the continued development and application of dynamic nuclear polarization (DNP), a powerful electron.spin/nuclear.spin double.resonance technique that enhances the nuclear spin polarization in Nuclear Magnetic Resonance (NMR) experiments on materials containing both magnetic nuclei and unpaired electrons. DNP is especially important in the characterization of Chinese and U.S. coals and diamond.like carbon films prepared in Chinese and U.S. laboratories. For the coal studies, the striking differences between magnetic resonance properties measured for U.S. and certain Chinese coals will be examined in depth, and structural models will be explored for explaining both types of coals and these specific differences. In the diamond film studies, the nature of "defect" structures will be elucidated and related to film properties and preparation methods. The unusual field strength used in the 1.9 T DNP spectrometer in the Wuhan Institute of Physics will provide a good opportunity for elucidating fundamental details of the DNP phenomenon in these samples (via the field dependence of DNP properties) and for establishing the optimum magnetic field for DNP studies of typical carbonaceous solids.