Nuclear Magnetic Resonance, Now Without Magnets
Materials Sciences Division's Alex Pines and colleagues have demonstrated the first high-resolution nuclear magnetic resonance (NMR) instrument capable of chemical analysis without large, cumbersome magnets. An inexpensive version of NMR, which reveals the identity and chemical environment of molecules or atoms, could help researchers fingerprint small quantities of a chemical in a variety of settings.
In traditional NMR, a large magnet is used to align magnetic spins within atoms. Radio waves disrupt these spins, which begin to precess, or wobble, in response. The degree of wobbling points to the chemical identity of a given molecular species. Here, these researchers exploited another aspect of spin behavior that is sensitive to geometry and relative orientation, but is independent of magnetic field.
This portable NMR device consists of a chamber designed to introduce a specific form of hydrogen gas into a chemical sample to polarize spins. The precession of these spins produces a distinct NMR spectrum, which identifies the chemical under investigation. This finding opens the door to a portable version of this technique.