Gizatullin, Bulat, Carlos Mattea, and Siegfried Stapf. “Overhauser DNP FFC Study of Block Copolymer Diluted Solution.” Magnetic Resonance Imaging 56 (February 2019): 96–102.
Overhauser dynamic nuclear polarization (DNP) is the dominating hyperpolarization technique to increasing the nuclear magnetic resonance signal in liquids and diluted systems. The enhancement obtained depends on the overall mobility of the radical-carrying molecule but also on its speciﬁc interaction with the host molecules. Information about the nature of molecular and radical dynamics can be identiﬁed from determining the nuclear T1 as a function of Larmor frequency by Fast Field Cycling (FFC) relaxometry. In this work, DNP and FFC methods were combined for a detailed study of 1H Overhauser DNP enhancements at 340 mT (X-band) and 73 mT (S-band) for diluted solutions of a block-copolymer with and without the addition of TEMPO radicals. NMR relaxation dispersions of these solutions are measured at thermal polarization and DNP conditions in the Xband, and the obtained DNP data were analyzed by a model of electron-nucleus interactions modulated by translational diﬀusion. The coupling factors for the two diﬀerent blocks of the copolymer are obtained independently from DNP and NMRD experiments. An additional contribution from scalar interactions was found for polystyrene blocks.