NUCLEAR SPIN RELAXATION IN LIQUID AND SOLID METHANE: ISOTOPE EFFECTS

1965 ◽  
Vol 43 (6) ◽  
pp. 986-1000 ◽  
Author(s):  
Gerald A. De Wit ◽  
Myer Bloom
Keyword(s):  
Relaxation Time ◽  
Melting Point ◽  
Spin Relaxation ◽  
Isotope Effects ◽  
Rotational Diffusion ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Molecular Reorientation ◽  
Temperature Range ◽  
Deuteron Spin

The deuteron spin–lattice relaxation time T1 and spin–spin relaxation time T2 have been studied in CD4 and CD3H between 55 °K and 110 °K. T1 was found to increase very slowly with temperature over the entire temperature range for CD4 with no measurable change being observable at the melting point. Since the deuteron spin relaxation is produced by intramolecular quadrupolar interactions, these results are in strong disagreement with the Debye rotational diffusion model often used to describe molecular reorientation. These results have been used to reanalyze the proton T1 data for CH4−nDn previously given by Bloom and Sandhu. The contributions to T1 from intermolecular dipolar interactions were found to be in close agreement with theory. Contributions from the spin–rotation interaction were found to be extremely small or zero in this temperature range. The effects of translational diffusion on the proton and deuteron T1 and T2 just below the melting point are also discussed.

Chlorine Nuclear Spin-Spin Relaxation Mechanism in Mg(H2O)6SnCl6 as Studied by NQR and NMR Techniques

1992 ◽  
Vol 47 (1-2) ◽  
pp. 277-282 ◽  
Author(s):  
Keizo Horiuchi ◽  
Daiyu Nakamura
Keyword(s):  
Relaxation Time ◽  
Spin Relaxation ◽  
Lattice Relaxation ◽  
Relaxation Mechanism ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Local Magnetic Field ◽  
Spin Lattice Relaxation Time ◽  
Spin Lattice ◽  
Increasing Temperature

AbstractThe 35Cl NQR spin-lattice relaxation time T1Q, spin-spin-relaxation time T2Q, and 1H NMR spin-lattice relaxation time in the rotating frame T1Q in Mg(H2O) 6SnCl6 were measured as functions of temperature. Above room temperature T2Q increased rapidly with increasing temperature, which can be explained by fluctuations of the local magnetic field at the chlorine nuclei due to cationic motions. From the T1Q experiments, these motions are found to be attributable to uniaxial and overall reorientations of [Mg(H2O)6 ] 2 + ions with activation energies of 95 and 116 kJ mol - 1 , respectively. Above ca. 350 K, T1Q decreased rapidly with increasing temperature, which indicates a reorientational motion of [SnCl6] 2 - ions with an activation energy of 115 kJ mol -1 .

A nuclear magnetic resonance study of 1H, 23Na, and 31P relaxation and molecular dynamics in the sodium salts of some pyrophosphates

1989 ◽  
Vol 67 (6) ◽  
pp. 592-598 ◽  
Author(s):  
E. C. Reynhardt
Keyword(s):  
Relaxation Times ◽  
Lattice Relaxation ◽  
Laboratory Frame ◽  
Nuclear Magnetic Resonance Study ◽  
Spin Lattice Relaxation ◽  
Molecular Reorientation ◽  
Temperature Range ◽  
Spin Lattice ◽  
Second Moments ◽  
31P Relaxation

Proton second moments and spin-lattice relaxation times in the laboratory and rotating frames and 31P and 23Na spin-lattice relaxation times in the laboratory frame have been measured over the temperature region 295 > T > 100 K for the sodium pyrophosphate salts, Na2P2O7∙10H2O and Na2H2P2O7. Laboratory-frame 31P and 23Na spin-lattice relaxation times have also been measured over the same temperature range for Na4P2O7. In the case of Na4P2O7∙10H2O, the results show clearly that the H2O molecules execute a twofold jump motion at higher temperatures. The potential barriers to these motions range from 30 to 40 kJ/mol. The 31P and 23Na relaxations are also influenced by these motions. The [Formula: see text] ion in Na2H2P2O7 is stationary over the temperature range studied. T1(Na) is most probably dominated by acoustical lattice vibrations. The [Formula: see text] ion in Na4P2O7 is not involved in a molecular reorientation. A shallow T1(P) minimum of 55 s is associated with a limited motion of the pyrophosphate molecule.

INTERACTION BETWEEN DRUGS AND BIOMEDICAL MATERIALS I: BINDING POSITION OF BEZAFIBRATE TO HUMAN SERUM ALUBMIN

2012 ◽  
Vol 06 ◽  
pp. 751-756
Author(s):  
MASAMI TANAKA ◽  
KEIJI MINAGAWA ◽  
MOHAMED R. BERBER ◽  
INAS H. HAFEZ ◽  
TAKESHI MORI
Keyword(s):  
Relaxation Time ◽  
Human Serum ◽  
Spin Relaxation ◽  
Chemical Shifts ◽  
Equilibrium Dialysis ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Relaxation Rates ◽  
Binding Position

The interaction between bezafibrate (BZF) and human serum albumin (HSA) was investigated by equilibrium dialysis. Since the binding constant of BZF to HSA was independent of ionic strength and decreased with the addition of fatty acid, the interaction between BZF and HSA was considered to be due to hydrophobic mechanism. Chemical shifts in 1H-NMR spectra of BZF were independent of the concentration of BZF and addition of HSA. Spin-lattice relaxation time (T1) and spin-spin relaxation time (T2) of respective protons of BZF were independent of the concentration, but depended on the concentration of HSA added. The binding position of BZF to HSA was considered to involve the hydrophobic aromatic moiety of BZF from the ratio of spin-spin relaxation rates (1/T2) of BZF bound to HSA and free BZF.

Quadrupolar spin relaxation mechanisms for 235U in liquid UF6

1989 ◽  
Vol 67 (1) ◽  
pp. 52-55
Author(s):  
I. Ursu ◽  
M. Bogdan ◽  
F. Balibanu ◽  
Z. Gulacsi ◽  
M. Gulacsi ◽  
...  
Keyword(s):  
Relaxation Time ◽  
Electric Fields ◽  
Spin Relaxation ◽  
Nuclear Spin ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Spin Lattice ◽  
Nuclear Spin Lattice Relaxation ◽  
Quadrupolar Relaxation

The nuclear spin lattice relaxation time is calculated for 235U situated at the center of an octahedral 235UF6 molecule. Vibrational distortion, collisional deformation, and electric fields induced by neighbouring hexadecapole moments are considered as possible mechanisms that could account for the observed 235U quadrupolar relaxation rate. The efficiency of these mechanisms in causing relaxation is discussed by comparing the calculated value with the experimentally determined one.

Hydrosulfide-ion dynamics in cesium and rubidium hydrosulfide: a deuteron nuclear magnetic resonance study

1986 ◽  
Vol 64 (7) ◽  
pp. 833-838
Author(s):  
Kenneth R. Jeffrey ◽  
Roderick E. Wasylishen
Keyword(s):  
Quadrupole Interaction ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Site Symmetry ◽  
Time Data ◽  
Molecular Reorientation ◽  
Temperature Range ◽  
Spin Lattice ◽  
Nuclear Quadrupole

RbSD and CsSD have a multiplicity of solid-state phase transitions involving changes in the degree of order of the SD− ion. Because the deuteron has a nuclear quadrupole moment, the observed NMR spectrum reflects any changes that take place in the deuteron-site symmetry as a result of a phase change. Furthermore, the magnitude of the observed nuclear quadrupole interaction depends on the time average of the electric-field gradient at the deuteron site; this, in general, is a function of any molecular motion in the crystal. The nuclear spin–lattice relaxation times provide information about the time scale of any molecular reorientation taking place in the crystal structure. Deuteron NMR spectra and relaxation times are presented for RbSD and CsSD over the temperature range from 100 to 400 K. The spin–lattice relaxation time data show that there is reorientation of the SD− ion in the tetragonal phase of CsSD and in the trigonal phase of RbSD. While the correlation time for the reorientation changes from being short compared with the reciprocal of the quadrupole interaction to being the same order of magnitude in the temperature range studied, the deuterium NMR line shapes do not change substantially. It is concluded that the observed reorientation of the SD− ion in both RbSD and CsSD in the low-temperature noncubic phases is end-for-end flipping of the SD− ion since only reorientation by 180° leaves the static quadrupole splitting unchanged.

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