Nuclear Magnetic Resonance

Name:
Nuclear Magnetic Resonance
Detailed information:
(NMR). A type of radio-frequency spectroscopy based on the magnetic field generated by the spinning of electrically charged atomic nuclei. This nuclear magnetic field is caused to interact with a very large (10,000–50,000 gauss) magnetic field of the instrument magnet. The magnetic properties of atomic nuclei are the spin number and the magnetic moment. Hydrogen nuclei, fluorine, phosphorus, boron, nitrogen, carbon-13, and oxygen-17 have distinctive magnetic properties. The molecular or chemical environment of the nucleus produces characteristic shifts and fine structure in the NMR spectra. Because of its dependence on molecular structure, NMR has become a fundamental research tool for structure determinations in organic chemistry. Studies of hydrogen locations in crystals have been useful, as these cannot be determined directly by means of X rays. NMR techniques have been applied to studies of electron densities and chemical bonding, the composition of mixtures, percentage purity determinations, and elemental hydrogen analyses.