Near-zero-field nuclear magnetic resonance

TL;DR

This paper explores nuclear magnetic resonance in near-zero magnetic fields, revealing how small fields cause spectral splitting and provide additional molecular information, supported by experiments and theoretical analysis.

Contribution

It introduces a new understanding of near-zero-field NMR, showing how small magnetic fields affect spectra and offering simple rules for interpretation.

Findings

Spectral splitting occurs due to small magnetic fields in near-zero-field NMR.

Experimental results align with perturbation theory and numerical simulations.

New rules enable interpretation of complex spectra in near-zero-field conditions.

Abstract

We investigate nuclear magnetic resonance (NMR) in near-zero-field, where the Zeeman interaction can be treated as a perturbation to the electron mediated scalar interaction (J-coupling). This is in stark contrast to the high field case, where heteronuclear J-couplings are normally treated as a small perturbation. We show that the presence of very small magnetic fields results in splitting of the zero-field NMR lines, imparting considerable additional information to the pure zero-field spectra. Experimental results are in good agreement with first-order perturbation theory and with full numerical simulation when perturbation theory breaks down. We present simple rules for understanding the splitting patterns in near-zero-field NMR, which can be applied to molecules with non-trivial spectra.