DNP (dynamic nuclear polarization) experiments at 5 T are reported, in which a cycoltron resonance maser (gyrotron) is utilized as a 20 W, 140 GHz microwave source to perform the polarization. MAS (magic angle spinning) NMR spectroscopy with DNP has been performed on samples of polystyrene doped with the free radical BDPA (,-bisdiphenylene - phenylallyl) at room temperature. Maximal DNP enhancements of 10 for H1 and 40 for C13 are observed and are considerably larger than expected. The DNP and spin relaxation mechanisms that lead to these enhancements at 5 T are discussed.
ASJC Scopus subject areas
- Physics and Astronomy(all)