High-Resolution,>1GHzNMR in Unstable Magnetic Fields

Resistive or hybrid magnets can achieve substantially higher fields than those available in superconducting magnets, but their spatial homogeneity and temporal stability are unacceptable for high-resolution NMR. We show that modern stabilization and shimming technology, combined with detection of intermolecular zero-quantum coherences (iZQCs), can remove almost all of the effects of inhomogeneity and drifts, while retaining chemical shift differences and $J$ couplings. In a 25-T electromagnet (1 kHz/s drift, 3 kHz linewidth over $1{\mathrm{cm}}^3$), iZQC detection removes $>99\mathrm{}\%$ of the remaining inhomogeneity, to generate the first high-resolution liquid-state NMR spectra acquired at $>1\mathrm{}\mathrm{GHz}$.