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.
@article{arxiv.1107.1706,
title = {Near-zero-field nuclear magnetic resonance},
author = {Micah Ledbetter and Thomas Theis and John Blanchard and Hattie Ring and Paul Ganssle and Stephan Appelt and Bernhard Bluemich and Alex Pines and Dmitry Budker},
journal= {arXiv preprint arXiv:1107.1706},
year = {2015}
}