A 15 N dynamic nuclear polarization (DNP) experiment is reported in which a 15 N DNP enhancement factor of approximately 2.6 X 102 is obtained on free radical doped samples of 99% 15N labeled benzamide. The free radicals BDPA (1:1 complex of a, y-bisdiphenylene-B-phenylallyl with benzene) and DPPH (2,2-Di(4-tert-octylphenyl)-1-picrylhydrazyl) are used as dopants and the spin relaxation effects of adding these dopants are studied by means of changes in proton and nitrogen T1 values of the samples. The combination in solids of a very low natural abundance, 0.37%, a small gyromagnetic ratio, and a long spin-lattice relaxation time for 15N nuclei create severe sensitivity problems that, in large part, are ameliorated by the signal enhancement observed in the 15N DNP experiment on samples containing free electrons.
Revised: June 22, 2018 |
Published: April 1, 1997
Citation
Hu J., J. Zhou, B. Yang, L. Li, J. Qiu, C. Ye, and M.S. Solum, et al. 1997."Dynamic Nuclear Polarization of Nitrogen-15 In Benzamide".Solid State Nuclear Magnetic Resonance 8, no. 2:129-137.PNNL-SA-35523.doi:10.1016/S0926-2040(96)01263-5