Parahydrogen enhanced zero-field nuclear magnetic resonance

TL;DR

This paper demonstrates high-resolution zero-field NMR using parahydrogen induced polarization, enabling sensitive, magnet-free chemical analysis with clear spectral features for molecular identification.

Contribution

It introduces a method for direct detection of zero-field NMR signals enhanced by parahydrogen, achieving high sensitivity without magnets.

Findings

Able to detect 13C-1H J-couplings in natural abundance samples

Spectra show clear, interpretable features for chemical fingerprinting

Single transient detection of zero-field NMR signals

Abstract

Nuclear magnetic resonance (NMR), conventionally detected in multi-tesla magnetic fields, is a powerful analytical tool for the determination of molecular identity, structure, and function. With the advent of prepolarization methods and alternative detection schemes using atomic magnetometers or superconducting quantum interference devices (SQUIDs), NMR in very low- (~earth's field), and even zero-field, has recently attracted considerable attention. Despite the use of SQUIDs or atomic magnetometers, low-field NMR typically suffers from low sensitivity compared to conventional high-field NMR. Here we demonstrate direct detection of zero-field NMR signals generated via parahydrogen induced polarization (PHIP), enabling high-resolution NMR without the use of any magnets. The sensitivity is sufficient to observe spectra exhibiting 13C-1H J-couplings in compounds with 13C in natural abundance in a single transient. The resulting spectra display distinct features that have straightforward interpretation and can be used for chemical fingerprinting.