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

TL;DR

This paper reports achieving 61% proton polarization at room temperature using triplet-DNP with a new host molecule, demonstrating potential for hyperpolarization applications.

Contribution

Introduction of dibenz[a, h]anthracene as a new host molecule enabling high proton polarization at room temperature in triplet-DNP.

Findings

Achieved 61% 1H polarization at room temperature.

Dibenz[a, h]anthracene provides long T1 relaxation times.

Paramagnetic relaxation dominates over spin-lattice relaxation.

Abstract

1H polarization of 61% was achieved by Dynamic Nuclear Polarization using photoexcited triplet electrons (Triplet-DNP) at room temperature and in 0.64 T. We introduced dibenz[a, h]anthracene as a new host molecule of the polarizing agent, pentacene-d14. Its rigid structure provides a long spin-lattice relaxation time (T1) of more than 2 hours at room temperature. The single crystal of dibenz[a, h]anthracene doped with 0.05 mol% pentacene-d14 was grown by the Bridgman method, and cut into a small piece of ~1 mg for Triplet-DNP experiment. The 1H polarization buildup and relaxation measurements indicated that paramagnetic relaxation became the major source of the relaxation than spin-lattice relaxation. Finally, two promising applications of room-temperature hyperpolarization, i .e. nuclear ordering and radiation-tolerant polarized target, are discussed.