Low-Frequency Excitation of Singlet-Triplet Transitions. Application to Nuclear Hyperpolarization

TL;DR

This paper demonstrates how low-frequency magnetic fields can induce singlet-triplet transitions in coupled nuclear spins, enabling significant hyperpolarization of carbon-13 nuclei from hydrogen spin pairs, with potential applications in magnetic resonance.

Contribution

It introduces a novel method for hyperpolarization using low-frequency excitation of singlet-triplet transitions in coupled nuclear spins.

Findings

Hyperpolarization of ${}^{13} ext{C}$ achieved from hydrogen spin pairs.

Effective excitation of singlet-triplet transitions demonstrated.

Potential for enhanced NMR sensitivity in molecular systems.

Abstract

Coupled pairs of nuclear spins-1/2 support one singlet state and three triplet states. Transitions between the singlet state and one of the triplet states may be driven by an oscillating low-frequency magnetic field, in the presence of couplings to a third nuclear spin, and a weak bias magnetic field.This phenomenon allows the generation of strong nuclear hyperpolarization of ${}^{13}\mathrm{C}$ nuclei, starting from the nuclear singlet polarization of a ${}^{1}\mathrm{H}$ spin pair, associated with the enriched para spin isomer of hydrogen gas. Hyperpolarization is demonstrated for two molecular system.