Chromatography Techniques and Spectrometry

Nuclear Magnetic Resonance (NMR)

Nuclear magnetic resonance (NMR) is a physical aspect in which magnetic field absorb and re-emit electromagnetic radiation in a nuclei. Depending on the strength of the magnetic field and the magnetic properties of the isotope of the atoms, this energy is at a specific resonance frequency which; the frequency is similar to television broadcasts (60–1000 MHz) VHF and UHF in practical applications. Observation of specific quantum mechanical magnetic properties of the atomic nucleus, NMR can be used. To study many other topics like molecular physics, crystals, and non-crystalline materials through nuclear magnetic resonance spectroscopy many scientific techniques exploit NMR phenomena. In advanced medical imaging techniques such as in magnetic resonance imaging (MRI) NMR is also routinely used.

Intrinsic magnetic moment and angular momentum can be found in odd number of protons and/or neutrons of isotopes. H and C are the most commonly studied nuclei, high-field NMR spectroscopy is used to study nuclei from isotopes of many other elements (e.g. H, Li, B, B, N, N, O, F, Na, Si, P, Cl, Cd, Xe, Pt) as well. Resonance frequency of a particular substance is directly proportional to the strength of the applied magnetic field is the key feature of NMR. In imaging techniques it is this feature that is exploited; in a non-uniform magnetic field if a sample is placed then the sample's nuclei’s resonance frequencies depend on where they are located in the field. Many efforts are made to develop increased field strength, often using superconductors, since the resolution of the imaging technique depends on the magnitude of magnetic field gradient. Using hyperpolarization, using multi-frequency techniques like two-dimensional, three-dimensional and higher-dimensional the effectiveness of NMR can also be improved.