Nuclear magnetic resonance
hideNuclear magnetic resonance (NMR) is a property that magnetic nuclei have in a magnetic field and applied electromagnetic (EM) pulse, which cause the nuclei to absorb energy from the EM pulse and radiate this energy back out. The energy radiated back out is at a specific resonance frequency which depends on the strength of the magnetic field and other factors. This allows the observation of specific quantum mechanical magnetic properties of an atomic nucleus. Many scientific techniques exploit NMR phenomena to study molecular physics, crystals and non-crystalline materials through NMR spectroscopy. NMR is also routinely used in advanced medical imaging techniques, such as in magnetic resonance imaging (MRI).
All nuclei that contain odd numbers of nucleons have an intrinsic magnetic moment and angular momentum, in other words a spin > 0. The most commonly studied nuclei are 1H (the most NMR-sensitive isotope after the radioactive 3H) and 13C, although nuclei from isotopes of many other elements (e.g. 2H, 10B, 11B, 14N, 15N, 17O, 19F, 23Na, 29Si, 31P, 35Cl, 113Cd, 195Pt) are studied by high-field NMR spectroscopy as well.
A key feature of NMR is that the resonance frequency of a particular substance is directly proportional to the strength of the applied magnetic field. It is this feature that is exploited in imaging techniques; if a sample is placed in a non-uniform magnetic field then the resonance frequencies of the sample's nuclei depend on where in the field they are located. Since the resolution of the imaging techniques depends on how big the gradient of the field is, many efforts are made to develop more powerful magnets, often using superconductors. The effectiveness of NMR can also be improved using hyperpolarization, and/or using two-dimensional, three-dimensional and higher dimension multi-frequency techniques.
The principle of NMR usually involves two sequential steps:
The two fields are usually chosen to be perpendicular to each other as this maximises the NMR signal strength. The resulting response by the total magnetization (M) of the nuclear spins is the phenomenon that is exploited in NMR spectroscopy and magnetic resonance imaging. Both use intense applied magnetic fields (H0) in order to achieve dispersion and very high stability to deliver spectral resolution, the details of which are described by chemical shifts, the Zeeman effect, and Knight shifts (in metals).
NMR phenomena are also utilized in low-field NMR, NMR spectroscopy and MRI in the Earth's magnetic field (referred to as Earth's field NMR), and in several types of magnetometers.
For more information about Nuclear magnetic resonance, read the full article at
Wikipedia.
This text uses material from Wikipedia and is available under the GNU Free Documentation License.
News tagged with nuclear magnetic resonance
Reaching the summit of protein dynamics
Dec 10, 2009 |
5 / 5 (1) |
0
Understanding the incredibly speedy atomic mechanisms at work when a protein transitions from one shape to another has been an elusive scientific goal for years, but an essential one for elucidating the full ...
Fast, accurate urine test for pneumonia possible, study finds
Dec 09, 2009 |
4 / 5 (2) |
0
Doctors may soon be able to quickly and accurately diagnose the cause of pneumonia-like symptoms by examining the chemicals found in a patient's urine, suggests a new study led by UC Davis biochemist Carolyn ...
Wizard at circuits, physics
Dec 03, 2009 |
4.9 / 5 (14) |
0
(PhysOrg.com) -- Donhee Ham, Gordon McKay Professor of Electrical Engineering and Applied Physics, uses his personal energy and understanding of physics to design innovative integrated circuits.
A little magic provides an atomic-level look at bone
Chemistry / Analytical Chemistry
Dec 02, 2009 |
5 / 5 (1) |
0
(PhysOrg.com) -- A new study using solid-state NMR spectroscopy to analyze intact bone paves the way for atomic-level explorations of how disease and aging affect bone. The research by scientists at the University of Michigan ...
A challenge to improve Nuclear Magnetic Resonance for structural biology
Nov 30, 2009 |
4 / 5 (1) |
0
(PhysOrg.com) -- In structural biology, the only technique available to predict the three dimensional structure of large complex molecules in solution, such as proteins and DNA, is NMR spectroscopy. To catalyze improvements ...
Genetic analysis helps dissect molecular basis of cardiovascular disease
Nov 20, 2009 |
2 / 5 (1) |
0
Using highly precise measurements of plasma lipoprotein concentrations determined by nuclear magnetic resonance spectroscopy (NMR), researchers led by Daniel Chasman at Brigham and Women's Hospital and Harvard Medical School ...
An atomic-level look at an HIV accomplice
Nov 19, 2009 |
1 / 5 (1) |
0
(PhysOrg.com) -- Since the discovery in 2007 that a component of human semen called SEVI boosts infectivity of the virus that causes AIDS, researchers have been trying to learn more about SEVI and how it works, in hopes of ...
Shape of things to come: Structure of HIV coat could lead to new drugs
Medicine & Health / HIV & AIDS
Nov 12, 2009 |
not rated yet |
0
Structural biologists at the University of Pittsburgh School of Medicine have described the architecture of the complex of protein units that make up the coat surrounding the HIV genome and identified in it a "seam" of functional ...
Hyper-SAGE boosts remote MRI sensitivity
Oct 09, 2009 |
5 / 5 (1) |
0
A new technique in Magnetic Resonance Imaging dubbed "Hyper-SAGE" has the potential to detect ultra low concentrations of clincal targets, such as lung and other cancers. Development of Hyper-SAGE was led ...
Magnetic Resonance Now Also Comes In Tiny Quantities
Sep 29, 2009 |
5 / 5 (6) |
0
(PhysOrg.com) -- It is now possible to analyse very small samples using Nuclear Magnetic Resonance. Thanks to a specially constructed detector, a 'stripline', greater sensitivity can be achieved while maintaining the same ...
Chemists create protein structure database
Sep 09, 2009 |
not rated yet |
0
(PhysOrg.com) -- Any chemist with access to the Internet can now use a powerful tool to help them accurately identify the structure of a protein, thanks to recently published work led by Harold A. Scheraga, Cornell's Todd ...
Coming Soon: Tuberculosis Detection with a Chip?
Chemistry / Analytical Chemistry
Jul 29, 2009 |
not rated yet |
0
(PhysOrg.com) -- Many of the new techniques based on nanotechnology that have been developed for faster and more sensitive detection of pathogens fail in day-to-day clinical use because they require complex sample preparation ...
NMR on a microscale
Chemistry / Analytical Chemistry
May 12, 2009 |
5 / 5 (2) |
0
(PhysOrg.com) -- The technique well known from its use in MRI scanning - actually based on nuclear magnetic resonance (NMR) - can now also be applied to extremely small samples thanks to an ingenious combination ...
New imaging technique reveals structural changes in Tourette's
May 12, 2009 |
5 / 5 (2) |
0
Magnetization Transfer Imaging, MTI, has been used to visualize previously unknown alterations in the cerebral architecture of patients with Tourette's syndrome. The researchers, writing in the open access journal BMC Ne ...
First discovery of 'animals-only' pigment bilirubin in plants
Mar 11, 2009 |
4 / 5 (1) |
0
In a first-of-its-kind discovery that overturns conventional wisdom, scientists in Florida are reporting that certain plants — including the exotic “White Bird of Paradise Tree” -- make bilirubin. Until now, scientists thought ...
