Frequency dependence study of the proton spin relaxation in the re‐entrant nematic phase

1982 ◽  
Vol 76 (12) ◽  
pp. 5659-5661 ◽  
Author(s):  
Ronald Y. Dong
Keyword(s):  
Frequency Dependence ◽  
Spin Relaxation ◽  
Nematic Phase ◽  
Proton Spin

Proton Spin Relaxation Study of the Cholesteric‐to‐Nematic Phase Transition

1971 ◽  
Vol 55 (5) ◽  
pp. 2449-2451 ◽  
Author(s):  
Ronald Y. Dong ◽  
M. M. Pintar ◽  
W. F. Forbes
Keyword(s):  
Phase Transition ◽  
Spin Relaxation ◽  
Nematic Phase ◽  
Proton Spin ◽  
Relaxation Study

Frequency Dependence of Proton Spin Relaxation in Liquid Crystalline PAA

1975 ◽  
Vol 30 (4) ◽  
pp. 437-441 ◽  
Author(s):  
W. Wölfel ◽  
F. Noack ◽  
M. Stohrer
Keyword(s):  
Relaxation Time ◽  
Transition Temperature ◽  
Frequency Dependence ◽  
Spin Relaxation ◽  
Correlation Time ◽  
Liquid Crystalline ◽  
Larmor Frequency ◽  
Proton Spin ◽  
Isotropic Phase ◽  
Frequency Range

Abstract We report on measurements of the Larmor frequency dependence of the proton spin relaxation time T1 in the nematic and isotropic phase of p-azoxyanisole (frequency range: 3.8 kHz ≦ ωL/2 π≦75 MHz) . In both cases our results clearly support the Pincus-Cahane mechanism of spin relaxation by order fluctuations ("ωL−½-law") and exclude the alternative translational dif­fusion model (“ωL+½-law”). For the isotropic phase it was possible to evaluate the correlation time τ of the liquid crystalline order fluctuations from the observed T1 dispersion. As a function of the deviation ⊿ν=ν-νc from the critical nematic-isotropic transition temperature, νc= (136± 0.5)°C, we found τ=2.71·10-7-⊿ν-0.25s .

Frequency dependence of nuclear spin relaxation in paramagnetic transition-metal complexes

1976 ◽  
Vol 29 (9) ◽  
pp. 1885 ◽  
Author(s):  
DT Pegg ◽  
DM Doddrell
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Frequency Dependence ◽  
Transition Metal Complexes ◽  
Spin Relaxation ◽  
Nuclear Spin ◽  
Relaxation Times ◽  
Proton Spin ◽  
Spin Lattice Relaxation ◽  
Zero Field

Proton spin-lattice relaxation times have been determined as a function of magnetic field strength (H0) for a series of paramagnetic transition-metal complexes chosen so that, for some, the electron spin relaxation times (te) fall in the Redfield limit (te � tr) while for others te << tr being the rotational correlation time. When te � tr dominates the nuclear relaxation and the experimental results can be readily explained by Redfield theory. When te << tr current theory predicts the nuclear T1 values to get longer as H0 decreases. This is not observed experimentally. This can only be explained by using non-Redfield relaxation theory and by assuming the spacings of the electron-nuclear spin energy levels are not dominated by H0. It is shown that, although the trace of the zero-field splitting tensor is zero TrD = 0 because TrD is averaged by tr when te < tr the value of Dzz is important in determining the energy-level spacings. By this approach the frequency dependence can be explained. Experimentally, it is shown that a Phase Alternating Pulse Sequence (PAPS) is required to measure T1. The problem originates from interference from transverse magnetization. A density matrix theory of the PAPS sequence is presented.

Proton spin relaxation in water

1964 ◽  
Vol 9 (3) ◽  
pp. 239-241 ◽  
Author(s):  
J.G. Powles ◽  
D.W.G. Smith
Keyword(s):  
Spin Relaxation ◽  
Proton Spin

Proton spin-spin relaxation time of peel and flesh of navel orange varieties exposed to freezing temperature

2005 ◽  
Vol 85 (14) ◽  
pp. 2482-2486 ◽  
Author(s):  
Prem N Gambhir ◽  
Young J Choi ◽  
David C Slaughter ◽  
James F Thompson ◽  
Michael J McCarthy
Keyword(s):  
Relaxation Time ◽  
Spin Relaxation ◽  
Freezing Temperature ◽  
Proton Spin ◽  
Spin Relaxation Time ◽  
Navel Orange

scholarly journals Solid state proton spin relaxation in ethylbenzenes: Methyl reorientation barriers and molecular structure

1991 ◽  
Vol 95 (2) ◽  
pp. 828-835 ◽  
Author(s):  
Peter A. Beckmann ◽  
Laura Happersett ◽  
Antonia V. Herzog ◽  
William M. Tong
Keyword(s):  
Molecular Structure ◽  
Solid State ◽  
Spin Relaxation ◽  
Proton Spin

Proton spin relaxation in bisphenol-a polycarbonate, butyl rubber, and their composites

1970 ◽  
Vol 4 (4) ◽  
pp. 853-861 ◽  
Author(s):  
D. Stefan ◽  
H. Leverne Williams ◽  
D. R. Renton ◽  
M. M. Pintar
Keyword(s):  
Bisphenol A ◽  
Spin Relaxation ◽  
Butyl Rubber ◽  
Proton Spin ◽  
Bisphenol A Polycarbonate
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