An Intermolecular Single-Quantum Coherence Detection Scheme for High-Resolution Two-Dimensional J -resolved Spectroscopy in Inhomogeneous Fields

Abstract

A new pulse sequence based on intermolecular single-quantum coherences (iSQCs) is proposed to achieve high-resolution two-dimensional (2D) J-resolved spectra in inhomogeneous fields via three-dimensional (3D) acquisition. Since the iSQC evolution period and spin echo evolution period in this sequence are intrinsically insensitive to magnetic field inhomogeneities, high-resolution 2D J-resolved spectra can be recovered from nuclei in inhomogeneous fields by projecting the 3D data onto the 2D plane. Analytical expressions of the resulting signals were derived assuming the secular dipole–dipole interaction. Analyses of a solution sample placed in a deliberately unshimmed magnetic field and of a biological sample with intrinsic field inhomogeneities were performed. The results show that this sequence provides an attractive and efficient way to eliminate the influence of field inhomogeneities on 2D J-resolved spectra, which is potentially useful for characterizing complex chemical materials and studying biological metabolites in inhomogeneous fields.