1H polarization above 60 % at room temperature by triplet dynamic nuclear polarization

Abstract

We achieved 61 % 1H polarization at room temperature and in 0.64 T via Dynamic Nuclear Polarization using photoexcited triplet electrons (Triplet-DNP). Dibenz[ a, h ]anthracene was introduced as a new host for pentacene- d 14, providing a long spin-lattice relaxation time ( T 1) exceeding 2 h. Single crystals doped with 0.05 mol% pentacene- d 14 were grown by the Bridgman method and cut to ∼1 mg for experiments. The 1H polarization buildup and relaxation measurements indicated that paramagnetic relaxation dominates over spin-lattice relaxation. Finally, potential applications of room-temperature hyperpolarization, i.e. , nuclear ordering and radiation-tolerant polarized targets, were discussed.