Miniature and Tabletop Nuclear Magnetic Resonance Spectrometers

Abstract

The most striking component of nuclear magnetic resonance (NMR) spectrometers for chemical analysis used to be a large super‐conducting, confining NMR spectrometers to dedicated laboratories away from the chemical work bench. This situation has changed in 2010 with the invention of small permanent magnets capable of providing magnetic fields sufficiently homogeneous and stable to resolve the chemical shift. Up to then NMR with compact magnets was limited to materials testing by relaxation and diffusion measurements without chemical resolution. While sensitivity and spectral dispersion of high‐resolution tabletop NMR spectrometers are lower than those of hitherto conventional high‐field NMR spectrometers due to lower field strength, they can be operated with the whole methodology known from high‐field NMR but inside the chemical laboratory and under the fume hood. This shortens the time for chemical analysis in reaction control applications from hours to minutes and opens up new opportunities for reaction monitoring and analysis of hazardous compounds. The lower cost makes NMR available to a wider user community and drives the progress in simplification and automation of the measurement process. In the following, compact NMR machines and their uses for materials testing and chemical analysis are reviewed.