Accelerated Detection for Low-Field NMR Using Nonuniform Sampling and Improved Reconstruction

The low-field nuclear magnetic resonance (LF NMR) system allows rapid, on-site, and nondestructive detection of molecular structures using portable equipment. However, LF NMR suffers from limited resolution, low sensitivity, and poor stability, resulting in peak overlap and limitations in practical applications. In this work, an accelerated spectroscopic method that combines nonuniform sampling (NUS) with a fast and accurate low-rank reconstruction method is proposed to rapidly acquire and faithfully reconstruct high-resolution 2-D spectra. Benefiting from the NUS and the group sparsity constraint, this method reduces the acquisition time and reconstruction time to overcome the effects of field drift while preserving low-intensity broad peaks. Through theoretical analyses, both high-field and low-field nuclear magnetic resonance (NMR) spectra reconstruction experiments, and in situ reaction monitoring, we show that this accelerated method is effective and efficient in terms of preserving sensitivity, improving the spectral resolution, and monitoring the molecular structures of reactants in real time. Thus, this proposed accelerated method may expand the applicability of low-cost LF NMR systems in fast detection.