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Topic: Nuclear magnetic resonance


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In the News (Tue 25 Jun 19)

  
  Nuclear Magnetic Resonance
When the nuclear magnetic moment associated with a nuclear spin is placed in an external magnetic field, the different spin states are given different magnetic potential energies.
Note that the electron spin magnetic moment is opposite to the electron spin while the proton spin magnetic moment is in the direction of the proton spin.
The Larmor frequency of the electron spin is in the microwave region of the electromagnetic spectrum and is used in electron spin resonance.
hyperphysics.phy-astr.gsu.edu /hbase/nuclear/nmr.html   (523 words)

  
  Nuclear magnetic resonance
Nuclear magnetic resonance (NMR) is a physical phenomenon described independently by Felix Bloch and Edward Mills Purcell[?] in 1946 both of whom shared the Nobel Prize in physics in 1952 for their discovery.
NMR is used as a spectroscopy technique to obtain physical, chemical, and electronic properties of molecules.
The 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.
www.ebroadcast.com.au /lookup/encyclopedia/nm/NMR.html   (1591 words)

  
 Nuclear magnetic resonance - Biocrawler   (Site not responding. Last check: 2007-10-05)
Nuclear magnetic resonance (NMR) is a physical phenomenon based upon the magnetic property of an atom's nucleus.
NMR studies a magnetic nucleus, like that of a hydrogen atom, by aligning it with an external magnetic field and perturbing this alignment using an electromagnetic field.
NMR was first described independently by Felix Bloch and Edward Mills Purcell in 1946 both of whom shared the Nobel Prize in physics in 1952 for their discovery.
www.biocrawler.com /encyclopedia/NMR   (3699 words)

  
 NMR Spectroscopy
Nmr spectroscopy is therefore the energetically mildest probe used to examine the structure of molecules.
The magnitude or intensity of nmr resonance signals is displayed along the vertical axis of a spectrum, and is proportional to the molar concentration of the sample.
C nmr spectroscopy is the use of high-field pulse technology coupled with broad-band heteronuclear decoupling of all protons.
www.cem.msu.edu /~reusch/VirtualText/Spectrpy/nmr/nmr1.htm   (6080 words)

  
 Nuclear Magnetic Resonance (NMR)
Nuclear Magnetic Resonance (NMR) is an analysis technique that works by first exciting atoms in a sample using a high frequency magnetic pulse, then measuring the re-emitted radio signal from those same atoms as they return to normal.
When the radio frequency magnetic field is removed, the nuclear magnets revert back to their original orientations, emitting a decaying radio signal in the process.
This means that the frequency of the high frequency field required to twist the nuclear magnets, and the subsequent emitted radio signal, both depend on the chemical environment of each nuclear spin.
www.ifr.ac.uk /materials/fractures/NMR.html   (749 words)

  
 Nuclear magnetic resonance
Nuclear magnetic resonance is an experimental technique of importance in molecular structure elucidation.
Since a spinning charge generates a magnetic field, there is a magnetic moment associated with its moment (Also, the neutron has a magnetic moment).
The magnitude of the nuclear magnetic moment is specified in terms of the magnetogyric ratio
folk.uio.no /eugen/nmr.html   (826 words)

  
 Nuclear Magnetic Resonance
Nuclear magnetic resonance (NMR) of protons in bulk matter was first demonstrated in 1946 independently by F. Bloch and E. Purcell who were jointly awarded the Nobel prize for their discoveries in 1952.
In thermal equilibrium, the magnetization M produced by the protons in a sample is constant in magnitude and direction, so that it does not produce a changing magnetic flux at the coils shown in Fig.
To detect the magnetization M by coils lying in the xy plane of the laboratory frame, it is desirable to have the magnetization M lie in the x'y' plane so that the magnetization sweeps its associated magnetic field through the area of the coils as the magnetization precesses in the laboratory.
www.breadloaf.middlebury.edu /~PHManual/nuclearmag.html   (4090 words)

  
 Nuclear magnetic resonance - Wikipedia, the free encyclopedia
NMR studies a magnetic nucleus, like that of a hydrogen atom (protium being the most receptive isotope at natural abundance) by aligning it with a very powerful external magnetic field and perturbing this alignment using an electromagnetic field.
Nuclear magnetic resonance was first described independently by Felix Bloch and Edward Mills Purcell, in 1946, both of whom shared the Nobel Prize in physics in 1952 for their discovery.
A relatively recent example of nuclear magnetic resonance being used in the determination of a structure is that of buckminsterfullerene.
en.wikipedia.org /wiki/Nuclear_magnetic_resonance   (3317 words)

  
 The Nuclear Magnetic Resonance Laboratory
The Nuclear Magnetic Resonance Laboratory is responsible for maintaining the high field NMR spectrometers, training users, providing spectra on a service basis, and assisting users with design, execution, and interpretation of NMR experiments.
The NMR Lab received an 800 MHz instrument in September 2004 (and equipped it with a TCI cryoprobe in September 2005), housed in a specialized laboratory in room 100 of the new Structural Biology Center (SBC).
We received a triple resonance PFG cold probe for this instrument in July 2005.
www.msg.ku.edu /~msg/nmr2.html   (604 words)

  
 Nuclear Magnetic Resonance
In NMR, EM radiation is used to "flip" the alignment of nuclear spins from the low energy spin aligned state to the higher energy spin opposed state.
The realigned magnetic fields induce a radio signal in the output circuit which is used to generate the output signal.
Since the magnetic field strength dictates the energy separation of the spin states and hence the radio frequency of the resonance, the structural factors mean that different types of proton will occur at different chemical shifts.
www.mhhe.com /physsci/chemistry/carey/student/olc/ch13nmr.html   (2537 words)

  
 JEOL Nuclear Magnetic Resonance
The NMR signal is a natural physical property of the certain atomic nuclei but it can only be detected with an external magnetic field.
The NMR signal for most spectrometers is in the radio frequency part of the electromagnetic energy spectrum and NMR spectrometers are referred to by the proton NMR frequency, e.g.
Sample concentrations of solute for 1H NMR are usually in the range of 100ug to 5g, with 10 to 50mg being typical.
www.jeol.com /tabid/97/Default.aspx   (450 words)

  
 Introduction to MRI Physics, Page 1
Magnetic Resonance Imaging has at its root the chemical technique known as Nuclear Magnetic Resonance.
As every chemist knows, the use of the word "Nuclear" has nothing to do with radioactivity, but since the general population is not composed of mostly chemists, the medical community has dropped that emotion laden word to become, simply, MRI.
The faster it moves or the larger the charge, the larger the magnetic field it produces.
www.simplyphysics.com /page2_1.html   (228 words)

  
 Nuclear Magnetic Resonance Spectroscopy
H NMR allows for the #, type, and position of the H atoms in a molecule to be determined.
C NMR allows for the type and position of 13C atoms in a molecule to be determined.
NMR Spectroscopy: does involve transitions from lower energy spin states to higher energy spin states but uses a very different detection method, which will be very briefly and very incompletely mentioned in this course.
www.ipfw.edu /chem/262/262Spring04/262nt0411.htm   (1434 words)

  
 Nuclear Magnetic Resonance Spectroscopy
Nuclear Magnetic Resonance Spectroscopy, or NMR as it is usually called, is the same as a medical technique you may have heard of, MRI or Magnetic Resonance Imaging.
There's no need to fear, NMR and MRI use harmless radio waves to acquire their data, not the gamma rays that "nuke ya." In fact, radio waves are on the opposite end of the electromagnetic spectrum from gamma rays.
NMR is also a characterization technique where a sample is immersed in a magnetic field and hit with radio waves.
www.pslc.ws /mactest/nmr.htm   (895 words)

  
 Nuclear Magnetic Resonance (NMR)
The practical uses for this phenomenon are for determining the value of nuclear magnetic moments by comparison with the proton, the measurement of magnetic fields, and most recently for medical diagnostics.
Observe the behavior of the pattern as the RF level is varied, as frequency is varied, as the DC magnetic field is varied slightly, as the RF coil is moved away from the center of the gap, and as the modulating field amplitude and frequency are varied.
Without altering either the static (H_0) or modulating fields, the RF level, or the position of the coil in the magnet gap, replace the Teflon with machine oil, and measure the resonant frequency for protons (carefully adjust the frequency) in the same field.
www.its.caltech.edu /~derose/labs/exp5.html   (2248 words)

  
 Today's Chemist at Work -- Why NMR Is Attracting Drug Designers
Thirty-five years have gone by since NMR (nuclear magnetic resonance) spectroscopy first hit the analytical scene, and yet its capabilities and applications continue to evolve.
NMR allows you to observe the physical flexibility of proteins and the dynamics of their interactions with other molecules—a huge advantage when studying a protein’s biochemical function.
Only the initial experiments of SAR by NMR are exploratory in nature: screening for weakly bound, low molecular weight inhibitors of the target protein (the dissociation constant, a measure of a drug’s potency, is in the millimolar range).
pubs.acs.org /hotartcl/tcaw/00/jan/miller.html   (1874 words)

  
 Nuclear Magnetic Resonance - Search Results - MSN Encarta   (Site not responding. Last check: 2007-10-05)
Nuclear Magnetic Resonance, technique developed in the late 1940s by the Swiss-born United States physicist Felix Bloch for the spectroscopic...
Large, powerful magnets are crucial to a variety of modern technologies.
- energy pulse from atomic nucleus: the energy pulse released by an atomic nucleus exposed to high-frequency radiation in a magnetic field.
uk.encarta.msn.com /Nuclear_Magnetic_Resonance.html   (127 words)

  
 The Birth of MRI - Magnetic Resonance Imaging - Stony Brook Chemistry Department
The instrument on which Lauterbur performed this critical experiment was a Varian A-60 NMR spectrometer capable of detecting protons at 60 MHz.
The ability to perform non-invasive imaging of the interior of living organisms using nuclear magnetic resonance is one of the most important medical discoveries of the twentieth century.
Lauterbur left Stony Brook in 1985 to become the director of the Biomedical Magnetic Resonance Laboratory at the University of Illinois.
www.sunysb.edu /chemistry/news/mri.html   (189 words)

  
 Magnetic Nuclear Resonance
This is a simple application of the classical "resonance" effect - the most efficient transfer of energy is when the "transferer" is at the same frequency as the "transferee".
In this case the longitudinal and transverse magnetization they talk about are the respective projections of this vector along and orthogonal to the main magnetic field.
If the proton, spinning in the transverse plane imposed by the 90 degree RF wave amplitude,is relaxing and regaining his alignment with the main field, then any lost in his transverse magnetization is a gain in his longitudinal magnetization and the two phenomena are one.
www.physicsforums.com /showthread.php?p=313712   (3037 words)

  
 Nuclear Magnetic Resonance
Explain how the general orientation of magnetic nuclei change when tissue containing the nuclei is placed in a strong magnetic field.
Explain the concept of resonance as it applies to nuclear magnetic resonance.
Describe the relationship between resonant frequency of tissue and the strength of the magnetic field where the tissue is located.
www.sprawls.org /resources/MRINMR   (378 words)

  
 NUCLEAR MAGNETIC RESONANCE
In case the magnetic moment corresponds to a nuclear spin, then there it is associated an angular momentum and the combination of both, a torque and an angular momentum, gives rise to precession, like in the case of a turning "toy gyroscope" subjected to the torque produced by the action of the gravity.
The magnetisation, M, is a macroscopic field vector defined as the average magnetic moment per unit volume, n, n being the number of dipoles (spins) per unit volume.
This lack of synchronism is associated to the different magnetic fields that the spins see, mainly due to the magnetic fields of the neighbouring spins.
colos.fcu.um.es /colos/xdev/EXAMPLES/USERS/ernesto_nmr.html   (806 words)

  
 Edward Purcell and Nuclear Magnetic Resonance (NMR)
Edward M. Purcell was awarded the 1952 Nobel Prize in Physics for his "development of new methods for nuclear magnetic precision measurements and discoveries in connection therewith".
Purcell first observed nuclear magnetic resonance (NMR) in 1945 while working at the Massachusetts Institute of Technology (MIT) Radiation Laboratory in an after-hours experiment.
Purcell's stunning introductory textbook on Electricity and Magnetism has educated and inspired a generation of physicists, who refer to it often, and depend on it utterly.
www.osti.gov /accomplishments/purcell.html   (501 words)

  
 nuclear magnetic resonance (nmr) menu   (Site not responding. Last check: 2007-10-05)
An explanation of how an NMR spectrum arises, and the meaning of the term "chemical shift".
How a low resolution NMR spectrum is used to identify where the hydrogen atoms in a molecule are.
Looks at the additional information which you can get from a high resolution NMR spectrum.
www.chemguide.co.uk /analysis/nmrmenu.html   (76 words)

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