Development and research of X-band dynamic nuclear polarization system

In order to investigate the experimental technique and the high magnetic field effect in the dynamic nuclear polarization (DNP) experiments, the X-band 1H-DNP experiments have been performed on a organic solution of α ,γ-bisdiphenylene-β-phyenylallyl (BDPA) radical at room temperature. Because BDPA-doped toluene solution evaporated immediately during sub-THz irradiation, we tried DNP experiments with changing the solvent from toluene to benzene. As a result, we obtained similar DNP effects on the two solutions. We can expect that benzene solution is an appropriate sample for sub-THz DNP experiments. Further, we performed DNP measurements with degassed sample in order to avoid the relaxation due to oxygen in the sample solution. DNP enhancement observed in our measurements is well interpreted in terms of Overhauser effect