Study on ultra-low-field nuclear magnetic resonance spectroscopy based on high-sensitivity atomic magnetometer

The frequency of the spectral line and the splitting rule under the ultra-low magnetic field were theoretically given. Then, using the home-built ultra-low-field NMR spectrometer based on a high-sensitivity atomic magnetometer, an experimental study on ultra-low-field NMR spectroscopy was carried out. Taking a typical AXn-type organic molecule as an example, the J-coupling spectra under zero magnetic field was measured and the J-coupling parameters were accurately obtained by combining a theoretical analysis in a variety of organic molecules. For chemical samples with the same spectral structure under zero magnetic field, by applying a weak static magnetic field (nT) to the samples, it was observed that different samples have a unique ultra-low field NMR spectral splitting, which can be used as the "fingerprinting" of the sample to identify them.