COMMENT ON THE ARTICLES: "NUCLEAR MAGNETIC RELAXATION BY INTERMOLECULAR DIPOLE–DIPOLE INTERACTIONS", AND "NUCLEAR SPIN RELAXATION IN LIQUID AND SOLID METHANE: ISOTOPE EFFECTS"

1966 ◽  
Vol 44 (10) ◽  
pp. 2511-2513 ◽  
Author(s):  
B. H. Muller
Keyword(s):  
Spin Relaxation ◽  
Nuclear Spin ◽  
Magnetic Relaxation ◽  
Isotope Effects ◽  
Nuclear Magnetic Relaxation ◽  
Nuclear Spin Relaxation ◽  
Dipole Interactions ◽  
Solid Methane ◽  
Nuclear Magnetic

On the Role of Nuclear Spin Symmetry of Symmetric Top Molecules in Gas Phase Nuclear Magnetic Relaxation

1974 ◽  
Vol 52 (5) ◽  
pp. 387-395 ◽  
Author(s):  
B. C. Sanctuary
Keyword(s):  
Nuclear Spin ◽  
Magnetic Relaxation ◽  
Spin Symmetry ◽  
Nuclear Magnetic Relaxation ◽  
The Difference ◽  
Symmetric Top Molecules ◽  
Spin Species ◽  
Zero Frequency ◽  
Nuclear Magnetic

For symmetric top molecules the role of nuclear spin symmetry is included in the derivation of the nuclear magnetic relaxation rate. It is assumed that this is dominated by a spin-rotation mechanism. Of the three nuclear spin species which exist for ZX3Y' symmetric tops, it is found that the "zero frequency" K = −1 to +1 term results in two of the species relaxing with a different rate from the third. The difference, which allows a direct NMR evaluation of the relative values of [Formula: see text] and [Formula: see text], is enhanced at low temperatures.

scholarly journals Nuclear magnetic resonance and nuclear spin relaxation in AlAs quantum well probed by ESR

2016 ◽  
Vol 94 (24) ◽  
Author(s):  
A. V. Shchepetilnikov ◽  
D. D. Frolov ◽  
Yu. A. Nefyodov ◽  
I. V. Kukushkin ◽  
D. S. Smirnov ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Quantum Well ◽  
Spin Relaxation ◽  
Nuclear Spin ◽  
Nuclear Spin Relaxation ◽  
Nuclear Magnetic

The dynamics of water in heterogeneous systems

1977 ◽  
Vol 278 (959) ◽  
pp. 59-87 ◽  
Keyword(s):  
Neutron Scattering ◽  
Spin Relaxation ◽  
Nuclear Spin ◽  
Heterogeneous Systems ◽  
Proton Exchange ◽  
Nuclear Spin Relaxation ◽  
Water Molecules ◽  
Pure Liquid ◽  
Quasielastic Neutron ◽  
Nuclear Magnetic

The basic principles of nuclear spin relaxation, dielectric relaxation and quasielastic neutron scattering and their use in studying the motions of water molecules are outlined. A summary is given of the time scales associated with the translational and rotational motions of water molecules and of intermolecular proton exchange in pure liquid water. A model is then proposed for the dynamics of water molecules in heterogeneous systems involving regions having differing compositions, water molecules within each region existing in environments both affected by interaction with the macromolecular components and free of their influence and including exchange of water molecules between different environments and regions. The lifetime of the interaction of water molecules with the macromolecular components is assumed long compared with the time for rotation of such bound molecules. Exchange of protons between water molecules and between water molecules and macromolecules is also considered. The ways in which such processes would be expected to affect the observed nuclear magnetic resonance, dielectric and neutron scattering behaviour are outlined. Particular emphasis is placed on nuclear spin relaxation phenomena and the existence and observation of residual dipolar and quadrupolar splittings in the n.m.r. spectra of 1 H and 2 H (D) nuclei in water molecules in such systems, these splittings arising from water molecules dynamically oriented at water/macromolecule interfaces. Details are then given of particular studies of water molecule dynamics in heterogeneous systems using n.m.r., dielectric and neutron scattering techniques. The systems discussed include moist protein powders, protein solutions, phospholipid/ water and soap/water mesophases, clay/water systems and biological polymers and tissues. It is concluded that water in these systems is highly mobile, that water molecules affected directly by a macromolecule tumble anisotropically about all axes relative to the macromolecule with correlation times in the region of 10 -9 s at 260 K and that these molecules exchange with water molecules free of the influence of the macromolecule with a lifetime in the dynamically oriented state of the order of 10 -6 s at temperatures around 300 K. The ability of nuclear magnetic relaxation studies to distinguish water in different regions of a tissue is discussed and examples are given of the study of the rate of water transport across membranes using these techniques.

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