High-resolution NMR spectra under inhomogeneous fields via intermolecular double-quantum coherences.

High-resolution NMR spectroscopy is a powerful tool for analyzing molecular structures and compositions. Line-widths of conventional liquid NMR signals are directly proportional to the overall magnetic field inhomogeneity the sample experiences. In many circumstances, spatial and temporal homogeneity of the magnetic field is degraded. In this paper, a modified pulse sequence based on intermolecular double-quantum coherences (iDQCs) was proposed to obtain 1D high-resolution NMR spectra under inhomogeneous fields using 2D acquisition. Analytical expressions were derived from the intermolecular multiple-quantum coherence (iMQC) treatments. Both experimental and simulated spectra provide high-resolution 1D projection spectra similar to conventional 1D high-resolution spectra. Moreover, the apparent J coupling constants are threefold magnified, which allows a more accurate measurement of small J coupling constants.