Nuclear magnetic resonance spectroscopy relaxation

The impact strength increases almost linearly with gel content and thus with the degree of crosslinking (17). Figure 9.3 shows the increase of the molecular mobility with the impact strength for ABS. For HIPS it is claimed that the situation is quite similar. The molecular mobility of the soft phase particles is determined by nuclear magnetic-resonance spectroscopy relaxation measurements (16). 

Oldfield, E., Norton, R. S., and Allerhand, A. (1975)./. Biol. Chem. 250, 6368. Studies of Individual Carbon Sites of Proteins in Solution by Natural Abundance Carbon-13 Nuclear Magnetic Resonance Spectroscopy. Relaxation Behavior. 

The process is reversible, and the excited particle can thus return to the ground state by reemission of the radiation. This is known as the relaxation process. Relaxation following resonance is the basis for nuclear magnetic resonance spectroscopy. It turns... 

Liquids are difficult to model because, on the one hand, many-body interactions are complicated on the other hand, liquids lack the symmetry of crystals which makes many-body systems tractable [364, 376, 94]. No rigorous solutions currently exist for the many-body problem of the liquid state. Yet the molecular properties of liquids are important for example, most chemistry involves solutions of one kind or another. Significant advances have recently been made through the use of spectroscopy (i.e., infrared, Raman, neutron scattering, nuclear magnetic resonance, dielectric relaxation, etc.) and associated time correlation functions of molecular properties. 

Figure 15.16. H Relaxation of 1-naphthol protons with increasing humic acid concentration at pH 7. All protons are observed to relax at a similar rate, suggesting a nonselective interaction between the protons of 1-naphthol and humic acid. Reprinted from Simpson, M. I, Simpson, A. J., and Hatcher, R G. (2004). Noncovalent interactions between aromatic compounds and dissolved humic acid examined by nuclear magnetic resonance spectroscopy. Environ. Toxi. Chem. 23, 355-362, with permission from the Society of Environmental Toxicology and Chemistry.

In addition to the specific references given in the chapter, much of the classic treatment of relaxation comes from the book by Abragam,33 but there are many other discussions of this subject in almost every book on NMR. Additional details along the lines presented here are given in Pulse and Fourier Transform NMR by Thomas C. Farrar and Edwin D. Becker,97 Nuclear Magnetic Resonance Spectroscopy by Robin K. Harris,32 and The Nuclear Overhauser Effect in Structural and Conformational Analysis by D. Neuhaus and M. P. Williamson.98... 

Secondary Relaxation Processes in Molecular Glasses Studied by Nuclear Magnetic Resonance Spectroscopy... 

Peters, J.A., Huskens, J., and Raber, D.J. (1996) Lanthanide induced shifts and relaxation rate enhancements. Progress in Nuclear Magnetic Resonance Spectroscopy, 28, 283-350. 

For NMR of solid-liquid interfaces, see K.J. Packer. Nuclear Spin Relaxation Studies of Molecules Adsorbed on Surfaces, in Progress in Nuclear Magnetic Resonance Spectroscopy, J.W. Emsley, J. Feeney and L.H. Sutcliffe. Eds., Vol. 3. Pergamon (1967), chapter 3. 87 A collection of papers on magnetic resonance in colloid and interface science can be found in Colloids Surf 72 (1993). 

The addition of a chemical species with a large dielectric constant to induce desired microwave effects in matrices devoid of such substances, or lacking substances with significantly different dielectric constants, can be compared, on a conceptual basis, to cross-polarisation experiments carried out in nuclear magnetic resonance spectroscopy (see Chapter 6). In that case, a nucleus that relaxes relatively rapidly is excited selectively and allowed to transfer that excitation energy to neighbouring nuclei with low or relatively lower relaxation rate (e.g., nuclei being cross-polarised to nuclei). 

Secondary relaxations are usually measured either by mechanical methods such as dynamic mechanical spectroscopy or (somewhat less often) by electrical methods such as dielectric relaxation spectroscopy [159], The existence of Tp is generally ascribed to the onset of a significant amount of some kind of motion of the polymer chains and/or the side groups attached to them, on a much smaller and more localized scale than the large-scale cooperative motions of chain segments associated with Ta. These motions are usually inferred from the results of measurements using methods such as nuclear magnetic resonance spectroscopy. See... 

Independent and reliable evidence that the temperature rbreak near 300 K is a singular point for water is given by the method of nuclear magnetic resonance (NMR) relaxation spectroscopy. 

Nuclear magnetic resonance spectroscopy (chapters BUT, B1.12. B1.13 and B1.14) can provide eross-relaxation rates between two proton spins, from which a set of short range (up to 5 A) distance constraints can be generated... 

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