Raman Studies of Molecular Reorientation in Liquid Sulfur Hexafluoride

1974 ◽  
Vol 52 (13) ◽  
pp. 1209-1214 ◽  
Author(s):  
S. Sunder ◽  
R. E. D. McClung
Keyword(s):  
Sulfur Hexafluoride ◽  
Fourier Transforms ◽  
Raman Band ◽  
Rotational Diffusion ◽  
Diffusion Limit ◽  
Molecular Reorientation ◽  
Rotation Tensor ◽  
Liquid Sulfur ◽  
Correlation Times ◽  
Tensor Formula

The contour of the v2 Raman band of SF6 liquid has been studied over the temperature range 226–315 K. Reorientational and angular momentum correlation times were obtained by comparing the Fourier transforms of the band contours with the reorientational correlation functions calculated using the J diffusion limit of the extended rotational diffusion model. A reanalysis of Hackleman and Hubbard's nuclear relaxation data for liquid SF6, using the correlation times obtained from the Raman studies, yields the value ± 6.2 × 104 s−1 for the asymmetry in the spin–rotation tensor [Formula: see text] for fluorine nuclei in SF6.

Raman spectral studies of molecular reorientation in liquid tetramethylsilane

1976 ◽  
Vol 54 (2) ◽  
pp. 211-216 ◽  
Author(s):  
S. Sunder ◽  
R. E. D. McClung
Keyword(s):  
Fourier Transforms ◽  
Rotational Diffusion ◽  
Spectral Studies ◽  
Diffusion Limit ◽  
Nuclear Relaxation ◽  
Molecular Reorientation ◽  
Correlation Times ◽  
Momentum Correlation ◽  
Relaxation Study ◽  
Raman Spectral

The contours of five Raman bands of liquid tetramethylsilane have been studied over the temperature range 178–350 K. Two bands were further analyzed to obtain the reorientational and angular momentum correlation times by removing the contributions from nonreorientational broadening and comparing the corrected Fourier transforms of the bands with the reorientational correlation functions calculated using the J diffusion limit of the extended rotational diffusion model. The agreement between the correlation times obtained from the analysis of the two Raman bands and those obtained from the nuclear relaxation study of liquid tetramethylsilane is satisfactory.

Proton Spin Relaxation of a Liquid Crystal with a Glassy Cholesteric State

1990 ◽  
Vol 45 (9-10) ◽  
pp. 1077-1084 ◽  
Author(s):  
D. Pusiol ◽  
F. Noack ◽  
C. Aguilera
Keyword(s):  
Spin Relaxation ◽  
Rotational Diffusion ◽  
Glassy State ◽  
Larmor Frequency ◽  
Proton Spin ◽  
Relaxation Dispersion ◽  
Proton Relaxation ◽  
Relaxation Processes ◽  
Molecular Reorientation ◽  
Cholesteric Phase

Abstract Field-cycling and standard pulsed NMR techniques have been used to study the frequency dependence of the longitudinal proton spin relaxation time T x in the crystalline estradiol compound (+)3,1,7-ß-bis-(4n-butoxybenzoyloxy)-estra-1,3,5-(10)-trien or BET, which is a mesogenic material with a chiral molecular structure. From the measured Larmor frequency and temperature depen-dences we conclude that, at low NMR frequencies in the cholesteric phase, T1 reflects in addition to the relaxation process familiar from nematic liquid crystals (director fluctuation modes) another slow mechanism theoretically predicted for cholesteric systems, namely diffusion induced rotational molecular reorientation. These relaxation processes are not or much less effective in the crystalline and glassy state, where they are frozen. Also the high NMR frequency relaxation dispersion strongly differs between the cholesteric mesophase and the not liquid crystalline samples. This is interpreted by a change from essentially translational self-diffusion to rotational diffusion controlled proton relaxation.

scholarly journals Effects of Hydrogen Bonding on the Rotational Dynamics of Water-Like Molecules in Liquids: Insights from Molecular Dynamics Simulations

2020 ◽  
Vol 73 (8) ◽  
pp. 734
Author(s):  
W. A. Monika Madhavi ◽  
Samantha Weerasinghe ◽  
Konstantin I. Momot
Keyword(s):  
Molecular Dynamics ◽  
Hydrogen Bonding ◽  
Hydrogen Sulfide ◽  
Spin Relaxation ◽  
Rotational Diffusion ◽  
Molecular Geometry ◽  
Md Simulations ◽  
Water Molecules ◽  
Molecular Reorientation ◽  
Nmr Spin Relaxation

Rotational motion of molecules plays an important role in determining NMR spin relaxation properties of liquids. The textbook theory of NMR spin relaxation predominantly uses the assumption that the reorientational dynamics of molecules is described by a continuous time rotational diffusion random walk with a single rotational diffusion coefficient. Previously we and others have shown that reorientation of water molecules on the timescales of picoseconds is not consistent with the Debye rotational-diffusion model. In particular, multiple timescales of molecular reorientation were observed in liquid water. This was attributed to the hydrogen bonding network in water and the consequent presence of collective rearrangements of the molecular network. In order to better understand the origins of the complex reorientational behaviour of water molecules, we carried out molecular dynamics (MD) simulations of a liquid that has a similar molecular geometry to water but does not form hydrogen bonds: hydrogen sulfide. These simulations were carried out at T=208K and p=1 atm (~5K below the boiling point). Ensemble-averaged Legendre polynomial functions of hydrogen sulfide exhibited a Gaussian decay on the sub-picosecond timescale but, unlike water, did not exhibit oscillatory behaviour. We attribute these differences to hydrogen sulfide’s absence of hydrogen bonding.

Study of Heating Device for Sulfur Hexafluoride Gasification

2020 ◽  
Vol 18 (2) ◽  
pp. 157-163
Author(s):  
Hong Yu ◽  
Maoyong Cao ◽  
Tanbo Zhu ◽  
Fanming Liu
Keyword(s):  
Sulfur Hexafluoride ◽  
Steel Cylinder ◽  
Liquid Sulfur ◽  
Heating Device ◽  
Gas Insulated Switchgear ◽  
Temperature And Humidity ◽  
Speed Up ◽  
Specific Temperature

Sulfur hexafluoride (SF6) gas has been used to gas-insulated switchgear (GIS) because of its insulation properties and extinguishing characteristics. The processing of liquid sulfur hexafluoride from cylinders into GIS is endothermic. The processing gas inflation always leads to decrease SF6 gas inflation speed due to the lack of heat supplement and the infiltrated moisture will stick on the GIS equipment, especially at the valve outlet. In the paper, a heater detection device for sulfur hexafluoride (SF6) steel cylinder is developed. The new heater device will monitor and display the specific temperature and humidity of the valve outlet instantaneously and then heat and dry the sulfur hexafluoride (SF6) steel cylinder with automatic and stability. Then it helps to speed up the sulfur hexafluoride gasification. Meanwhile, the whole device is portable in safety.

Raman Band Shapes and Molecular Reorientation

1972 ◽  
Vol 57 (4) ◽  
pp. 1795-1796 ◽  
Author(s):  
Stanislav Sýkora
Keyword(s):  
Raman Band ◽  
Molecular Reorientation

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.

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