Cheng, T., et al., Over 35% liquid-state (13)C polarization obtained via dissolution dynamic nuclear polarization at 7 T and 1 K using ubiquitous nitroxyl radicals. Phys Chem Chem Phys, 2013. 15(48): p. 20819-22.
http://www.ncbi.nlm.nih.gov/pubmed/24217111
The most versatile method to increase liquid-state (13)C NMR sensitivity is dissolution dynamic nuclear polarization. The use of trityl radicals is usually required to obtain very large (13)C polarization via this technique. We herein demonstrate that up to 35% liquid-state (13)C polarization can be obtained in about 1.5 h using ubiquitous nitroxyl radicals in (13)C-labeled sodium salts by partially deuterating the solvents and using a polarizer operating at 1 K and 7 T.