Spin-1/2 nuclides resonance

A homonudear 2-D COSY NMR spectrum shows chemical shifts from the same nuclide on both the fj and fj axes. Signal normally appears on the diagonal where the analogous 1-D spectrum contains resonances (5j = 82). A signal off the diagonal is called a cross peak (81 52). The COSY cross peaks appear whenever the spins with resonances at 5j and 82 are coupled to each other. The intensity of COSY cross peaks varies in direct proportion to the magnitude of the J-cou-pling between the two resonances. 

Magnetic Resonance of Systems with Equivalent Spin-1/2 Nuclides... 

The situation has been elucidated in a series of recent papers Magnetic resonance in systems with equivalent spin-1/2 nuclides. 13 1 38 39 These works deal with EPR examples, that is each with an impaired electron exposed to a set of n equivalent 1=1/2 nuclei. For our present purpose, we can deem the electron to have been replaced by some spin-bearing nucleus to be examined by NMR. 

S. M. Nokhrin, J. A. Weil and D. F. Howarth, Magnetic resonance in systems with equivalent spin-1/2 nuclides. Part 1. J. Magn. Reson., 2005,174, 209-218. 

It is my pleasure to present Volume 71 of Annual Reports on NMR, which consists of a collection of reports on advances in many scientific areas due to the application of NMR techniques. The volume commences with an account of Magnetic Resonance of Systems with Equivalent Spin-1/2 Nuclides by J.A. Weil Protein Dynamics as Reported by NMR is presented by Z. Gaspari and A. Perczel Virtual MRS Spectral Simulation and its Applications is covered by B.J. Soher, K. Young and L. Kaiser F.H. Larsen reports on Simulation of Molecular Motion of Quadrupolar Nuclei in Solid State NMR finally, NMR Studies of Disorder in Condensed Matter Systems is discussed by K.P. Ramesh. My thanks are due to all of these reporters for their interesting and timely contributions. 

Many NMR studies of nuclides of low sensitivity (nucleus X) that are spin coupled to protons are now carried out by indirect detection of the proton resonance, primarily by multidimensional NMR methods that we discuss later. For such detection to be effective for an X that is in low natural abundance (such as 13C) or is selectively enriched, it is essential to discriminate against the much larger signal arising from proton resonances of molecules with a nonmagnetic form of the nuclide (e.g., t2C).We describe here two simple ways to achieve such discrimination. 

To bridge the gap between ideal and practical catalysts, optical spectroscopies, electron spin resonance (ESR), nuclear magnetic resonance (NMR), and Mossbauer spectroscopy can be used. All have been reviewed recently (373, 396), and some examples have been cited earlier (107, 108). Electron spin resonance has been used in several studies of electroorganic reactions (357,371). It can detect short-lived radicals resulting from electron transfer. Recent application of Mossbauer spectroscopy in situ in electrochemical cells deserves mentioning, although it addressed only the anodic polarization and film stability of Co- and Sn-coated electrodes (397,398). Extension to electrocatalytic studies involving Mossbauer nuclides seems feasible. 

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