Down-to-earth NMR spectrometry

An ultra-high-resolution nuclear magnetic resonance spectrometer has been developed that forgoes the usual expensive superconducting magnet and uses Earth's weak but free magnetic field instead (Nat. Phys., published online Jan. 22, dx.doi.org/10.1038/nphys211). Stephan Appelt of the Helmholtz Research Center in Jülich, Germany, and his coworkers used the instrument to obtain ¹H, ⁷Li, and ¹⁹F NMR spectra of common compounds such as benzene, aqueous LiCl, silicone oil, and a nonafluorohexene. Earth's magnetic field is characterized by its high homogeneity, which surpasses that of the best man-made magnets and provides better peak resolution with just a single NMR scan, the researchers report. NMR using Earth's magnetic field has been carried out previously, but earlier approaches required complex equipment, such as cryogenically cooled detectors. Appelt and his coworkers suppose that their simpler device will lead to the first inexpensive and field-portable NMR spectrometers that could be used for medical imaging (MRI), in-line chemical reaction monitoring, and environmental monitoring.