@article{Rossini:204313,
      title = {Dynamic Nuclear Polarization NMR Spectroscopy of  Microcrystalline Solids},
      author = {Rossini, Aaron J. and Zagdoun, Alexandre and Hegner,  Franziska and Schwarzwalder, Martin and Gajan, David and  Coperet, Christophe and Lesage, Anne and Emsley, Lyndon},
      publisher = {AMER CHEMICAL SOC},
      journal = {JOURNAL OF THE AMERICAN CHEMICAL SOCIETY},
      number = {40},
      volume = {134},
      pages = {16899-16908},
      year = {2012},
      abstract = {Dynamic nuclear polarization (DNP) solid-state NMR has  been applied to powdered microcrystalline solids to obtain  sensitivity enhancements on the order of 100. Glucose,  sulfathiazole, and paracetamol were impregnated with  bis-nitroxide biradical (bis-cyclohexyl-TEMPO-bisketal,  bCTbK) solutions of organic solvents. The organic solvents  were carefully chosen to be nonsolvents for the compounds,  so that DNP-enhanced solid-state NMR spectra of the  unaltered solids could be acquired. A theoretical model is  presented that illustrates that for externally doped  organic solids characterized by long spin-lattice  relaxation times (T-1(H-1) > 200 s), H-1-H-1 spin diffusion  can relay enhanced polarization over micrometer length  scales yielding substantial DNP enhancements (epsilon).  epsilon on the order of 60 are obtained for  microcrystalline glucose and sulfathiazole at 9.4 T and  with temperatures of ca. 105 K. The large gain in  sensitivity enables the rapid acquisition of C-13-C-13  correlation spectra at natural isotopic abundance. It is  anticipated that this will be a general method for  enhancing the sensitivity of solid-state NMR experiments of  organic solids.},
      url = {http://infoscience.epfl.ch/record/204313},
      doi = {10.1021/ja308135r},
}