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Home > Nuclear magnetic resonance

NMR is used as a spectroscopy technique to obtain physical, chemical, and electronic properties of molecules. It is also the underlying principle of Magnetic Resonance Imaging. NMR is one of the techniques that has been used to build quantum computers.

1 How NMR works

A single atomic nucleus can be thought of as a spinning charged body, which acts as a tiny magnet. An external magnetic field into which the sample material is placed exerts a torque on the nucleus that acts to align the nuclear magnetic field with the external field; however, since the nucleus is spinning, it will precess about the magnetic field instead of aligning with it. The angle of the nucleus's magnetic field is quantized (due to the quantization of angular momentum). However, when the angles are randomly oriented, in net, they will align with the magnetic field slightly.

The sample to be tested is placed in a static external magnetic field. The nuclei (on a quantum mechanical level) are all precessing at approximately the same rate, and more precessing with net magnetic field aligned with the magnet. Then an antenna (usually a coil-shaped inductor with the sample inside) is used to irradiate the sample with radio waves. At certain frequencies, atomic nuclei within the sample will absorb the radiation and align. so that they all precess in phase with each other, yielding a new changing magnetic field with a characteristic frequency. This field can be detected and its frequencies quantified via Fourier transformThe Fourier transform named for Jean Baptiste Joseph Fourier, is an integral transform that re-expresses a function in terms of sinusoidal basis functions, i. as a sum or integral of sinusoidal functions multiplied by some coefficients ("amplitudes")..

This can also be though of in the classical sense where the net magnetization vector of the sample is tilted and then begins to precess at its characteristic frequency.

Only nuclei with non zero magnetic momentIn physics, the magnetic moment of an object is a vector relating the aligning torque in a magnetic field experienced by the object to the field vector itself. The relationship is given by: : where tau is the torque, measured in newton · metres mu is the can undergo NMR. Such nuclei must have an odd number of protonsFor alternative meanings see proton (disambiguation). Proton Classification Subatomic particle Fermion Hadron Baryon Nucleon Proton Properties Mass: 938 MeV/ c2 Electric Charge: 1. 6 × 10−19 C Spin: 1/2 In physics, the proton is a subatomic particle or neutronsNeutron Classification Subatomic particle Fermion Hadron Baryon Nucleon Neutron Properties Mass: 940 MeV/ c 2 Electric Charge: 0 C Spin: 1/2 In physics, the neutron is a subatomic particle with no net electric charge and a mass of 940 MeV/ c 2 ( kg; very (e.g. ¹ Hhydrogen helium H Li Full table General Name, Symbol, NumberHydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1 (IA), 1 , s Density, Hardness 0. 0899 kg/m3, NA Appearance colorless Atomic properties Atomic weight 1. 00794 amu Atomic radius (ca, ¹³ CAlternative meaning: Carbon (computing Carbon is a chemical element in the periodic table that has the symbol C and atomic number 6. An abundant nonmetallic, tetravalent element, carbon has several allotropic forms: diamonds (hardest known mineral). Bindi, ¹⁵ NNitrogen is the chemical element in the periodic table that has the symbol N and atomic number 7. A common normally colorless, odorless, tasteless and mostly inert diatomic non-metal gas, nitrogen constitutes 78 percent of Earth's atmosphere and is a cons, ³¹ PPhosphorus is the chemical element in the periodic table that has the symbol P and atomic number 15. A multivalent, nonmetal of the nitrogen group, phosphorus is commonly found in inorganic phosphate rocks and in all living cells but is never naturally fo, ¹⁹ F).

A technique related to NMR is electron spin resonance that deals with electrons instead of nuclei. The principles are otherwise similar.

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Nuclear physicsNuclear physics is that branch of physics concerned with the nucleus of the atom. Topics include: Strong interaction Radioactivity Models of the nucleus liquid drop model shell model interacting boson model Fission Fusion Nuclear reactions Applications Nu Nuclear magnetic resonanceNuclear magnetic resonance NMR is a physical phenomenon involving the interaction of atomic nuclei placed in an external magnetic field with an applied electromagnetic field oscillating at a particular frequency. Magnetic conditions within the material ar Nuclear fusionIn physics, nuclear fusion (a thermonuclear reaction is a process in which two nuclei join, forming a larger nucleus and releasing energy. Nuclear fusion is the energy source which causes stars to shine, and hydrogen bombs to explode. It takes considerabl NucleariidThe nucleariids are a small group of amoebae with filose pseudopods, known mostly from soils and freshwater. They are distinguished from the similar vampyrellids mainly by having mitochondria with discoid cristae. Genetic studies place them near the anima Nuclear weaponmushroom cloud of the atomic bombing of Nagasaki, Japan, in 1945 lifted nuclear fallout some 60,000 feet (18 km) above the epicenter. A nuclear weapon is a weapon that derives its energy from nuclear reactions and has enormous destructive power a single n Nuclear envelopeThe nuclear envelope refers to the double membrane of the nucleus that encloses genetic material in eukaryotic cells. It separates the contents of the nucleus ( DNA in particular) from the cytosol. The space between the two membranes that make up the nucl Nuclear pore Nuclear Nuclear fission Nuclear Non-Proliferation Treaty Nuclear chain reaction Nuclear reactor Nuclear proliferation Nuclear disarmament Nuclear winter