Nuclear Overhauser effect: Difference between revisions
imported>Sekhar Talluri |
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==== '''Nuclear Overhauser effect''' ==== | ==== '''Nuclear Overhauser effect''' ==== | ||
Irradiation at the resonance frequency of one nucleus in the molecule may cause changes in the intensity of a signal at a different frequency corresponding to another nucleus - this is called the Nuclear Overhauser effect<ref>A.W.Overhauser (1953). Phys. Rev. 92, 411 </ref> (Noe). Nuclear overhauser effect is due to dipole-dipole interactions between the magnetic moments of the pair of nuclei. Unlike J-coupling, this interaction is not mediated through bonds and hence it may be possible to observe the Nuclear Overhauser effect between pairs of nuclei separated by many bonds provided that they are in spatial proximity. The strength of the observable Nuclear overhauser effect for molecules in solution is proportional to the inverse of the sixth power of the distance between the two nuclei due to averaging caused by rotational motion. Both the magnitude as well as the sign of the nuclear overhauser effect depend on the rotational frequencies of the pair of nuclei with respect to the applied magnetic field. | Irradiation at the resonance frequency of one nucleus in the molecule may cause changes in the intensity of a signal at a different frequency corresponding to another nucleus - this is called the Nuclear Overhauser effect<ref>A.W.Overhauser (1953). Phys. Rev. 92, 411 </ref> (Noe). Nuclear overhauser effect is due to dipole-dipole interactions between the magnetic moments of the pair of nuclei. Unlike J-coupling, this interaction is not mediated through bonds and hence it may be possible to observe the Nuclear Overhauser effect between pairs of nuclei separated by many bonds provided that they are in spatial proximity. The strength of the observable Nuclear overhauser effect for molecules in solution is proportional to the inverse of the sixth power of the distance between the two nuclei due to averaging caused by rotational motion. Both the magnitude as well as the sign of the nuclear overhauser effect depend on the rotational frequencies of the pair of nuclei with respect to the applied magnetic field. | ||
The Noe enhancement is quantitatively defined as | The Noe enhancement is quantitatively defined as <math>\eta = (S - So) / So </math> | ||
<math>\eta = </math> | |||
[[Category:CZ Live]] | [[Category:CZ Live]] | ||
[[Category:Stub Articles]] | [[Category:Stub Articles]] | ||
[[Category:Chemistry]] | [[Category:Chemistry]] | ||
Revision as of 04:28, 11 October 2008
Nuclear Overhauser effect
Irradiation at the resonance frequency of one nucleus in the molecule may cause changes in the intensity of a signal at a different frequency corresponding to another nucleus - this is called the Nuclear Overhauser effect[1] (Noe). Nuclear overhauser effect is due to dipole-dipole interactions between the magnetic moments of the pair of nuclei. Unlike J-coupling, this interaction is not mediated through bonds and hence it may be possible to observe the Nuclear Overhauser effect between pairs of nuclei separated by many bonds provided that they are in spatial proximity. The strength of the observable Nuclear overhauser effect for molecules in solution is proportional to the inverse of the sixth power of the distance between the two nuclei due to averaging caused by rotational motion. Both the magnitude as well as the sign of the nuclear overhauser effect depend on the rotational frequencies of the pair of nuclei with respect to the applied magnetic field. The Noe enhancement is quantitatively defined as
- ↑ A.W.Overhauser (1953). Phys. Rev. 92, 411