Nuclear Magnetic Resonance Without a Magnet

A group of German researchers have shown that a powerful chemical analysis technique, Nuclear Magnetic Resonance (NMR) spectroscopy, could lead to a highly sensitive way to measure the magnetic fields around living creatures, sample the Earth’s magnetic field, or test the composition of mineral oils in wells. The key to the advance is developing an NMR system that makes use of the relatively weak magnetic field of the Earth.

NMR spectroscopy is an analytical technique that relies on the fact that the nuclei of atoms have magnetic fields similar to those of common bar magnets. Placing atoms in a strong magnetic field and applying the appropriate radio signal can cause the nuclei to flip over and create signals that reveal information about the atoms and their environments. This makes NMR spectroscopy an important method for analyzing chemical composition and molecular structure.

NMR is also the phenomenon at the heart of Magnetic Resonance Imaging (MRI), one of the most powerful diagnostic tools in modern medicine.

When they were first developed, NMR systems employed very strong fields, generated by large, power-hungry magnets. In recent years, researchers have developed NMR techniques in ever weaker fields. Now S. Appelt et al. report that they have developed NMR techniques that rely only on the Earth’s natural, and very weak magnetic field.

The advance may turn NMR into a valuable analysis tool in places where large magnets are impractical, such as the tight confines of well holes. It may also lead to precise measurements of very weak magnetic fields, including those surrounding living creatures and the Earth itself.

See http://link.aps.org/abstract/PRL/v94/e197602

http://www.aps.org

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