Thermodiffusion in D<sub>2-</sub>HT und anderen Wasserstoffgemischen

Schirdewahn, J.; Klemm, A.; Waldmann, L.

doi:10.1515/zna-1961-0201

Cited by 55 publications

(13 citation statements)

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“…The physical reason for this phenomenon in liquids is not clear. In an old work by Schirdewahn et al 38 about gaseous mixtures, the moment of inertia part is vaguely related to the rotational diffusion contribution to the thermal diffusion. At the same time, it is obvious that the values of the main moments of inertia for a given molecule characterize its size ͑or van der Waals volume͒ and the mass distribution, while all three possible ratios ͑I x / I y , I x / I z , I y / I z ͒ characterize the shape.…”

Section: Discussion Of the Effect Of The Moment Of Inertiamentioning

confidence: 99%

Thermal diffusion measurements and simulations of binary mixtures of spherical molecules

Polyakov

Zhang

Müller‐Plathe

et al. 2007

The Journal of Chemical Physics

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Thermal diffusion forced Rayleigh scattering measurements on binary mixtures of carbon tetrabromide (CBr(4)), tetraethylsilane, and di-tert-butylsilane in carbon tetrachloride (CCl(4)) are reported at different temperatures and concentrations. The Soret coefficient of CBr(4) in CCl(4) is positive and S(T) of both silanes in CCl(4) is negative, which implies that the heavier component always moves to the cold side. This is the expected behavior for unpolar simple molecules. Both silanes have the same mass so the influence of the difference in shape and moment of inertia could be studied. For all three systems, S(T) decreases with decreasing CCl(4) concentration. The results are discussed in the framework of thermodynamic theories and the Hildebrand parameter concept. Additionally, the Soret coefficients for both silaneCCl(4) systems were determined by nonequilibrium molecular-dynamics calculations. The simulations predict the correct direction of the thermophoretic motion and reflect the stronger drive toward the warm side for di-tert-butylsilane compared to the more symmetric tetraethylsilane. The values deviate systematically between 9% and 18% from the experimental values.

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Section: Discussion Of the Effect Of The Moment Of Inertiamentioning

confidence: 99%

Thermal diffusion measurements and simulations of binary mixtures of spherical molecules

Polyakov

Zhang

Müller‐Plathe

et al. 2007

The Journal of Chemical Physics

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“…␦M = ͑M 1 − M 2 ͒ / ͑M 1 + M 2 ͒ and ␦I = ͑I 1 − I 2 ͒ / ͑I 1 + I 2 ͒ are the relative differences of the molar mass and the in-plane moment of inertia. The above relation had originally been applied to gaseous isotopic mixtures of hydrogen by Schirdewahn et al 9 and previously been proposed for binary gaseous mixtures of polyatomic molecules by Waldmann. 10 Molecular-dynamics simulations of Lennard-Jones liquids show that the differences in molecular mass, moment of inertia, diameter, and interaction strength contribute additively to S T in such a manner that the molecules with the higher mass, the higher moment of inertia, the smaller diameter, and the stronger interaction prefer the cold side.…”

Section: Introductionmentioning

confidence: 99%

Universal isotope effect in thermal diffusion of mixtures containing cyclohexane and cyclohexane-d12

Wittko

Köhler

2005

The Journal of Chemical Physics

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The Soret coefficients S(T) of the liquids acetone, benzene, benzene-d1, 1,3,5-benzene-d3, benzene-d5, benzene-13C6, benzene-d6, n-hexane, toluene, 1,2,3,4-tetrahydronaphthalene, isobutylbenzene, and 1,6-dibromohexane have been measured in protonated and perdeuterated cyclohexane by a transient holographic grating technique. It has been found that S(T) can be either positive or negative and even change its sign as a function of concentration. The isotope effect DeltaS(T)=-0.99 x 10(-3) K(-1), which is the change of S(T) after isotopic substitution of cyclohexane, neither depends on concentration nor on the nature of the mixing partner. Only in the case of the polar acetone is DeltaS(T) approximately 30% larger but still concentration independent. Based on the experimental findings, some general conclusions about the dependence of the Soret coefficient on molecular properties are drawn.

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“…B Z ' ( 8) from which the optimum pressure is derived as a solution of ( 9) The only term which depends on P in the expression of Eq. ( 8 ) is B :…”

Section: Maximum Separation Factormentioning

confidence: 99%

Optimum Pressure for Total-Reflux Operated Thermal Diffusion Column for Isotope Separation

Yamamoto

Makino

Kanagawa

1990

Journal of Nuclear Science and Technology

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A formula for prediction of the optimum operating pressure Popt of the thermal diffusion columns at total reflux is derived based on the approximate formulae for the column constants which can be evaluated analytically. The formula is expressed explicitly in terms of (1) a parameter of cold wall radius r c. and physical properties (evaluated at the reference mean temperature T) of gases to be separated, or pD' R!r~Mg, where f': viscosity, D': product of diffusion coefficient at a standard pressure and the standard pressure, R : gas constant, M: molecular weight and g: gravitational acceleration, (2) ratio of radii o between hot wire r~~, and rc, and (3) the ratio of the temperature difference LIT to the cold wall temperature Tc, in the formThe result is compared with experimental data; (1) binary monatomic gas systems, (2) multicomponent monatomic gas . systems, (3) isotopically substituted polyatomic systems, (4) systems of low atomic or molecular weight, and (5) mixtures of unlike gases; mainly obtained by Rutherford & coworkers. Although the formula is based on the rather rough approximation for the column constants, the optimum pressures predicted by the present formula are in successfully good agreement with the experimental data even for the systems of low atomic or molecular weight and that of mixtures of unlike gases.

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Thermodiffusion in D_2-HT und anderen Wasserstoffgemischen

Cited by 55 publications

References 0 publications

Thermal diffusion measurements and simulations of binary mixtures of spherical molecules

Thermal diffusion measurements and simulations of binary mixtures of spherical molecules

Universal isotope effect in thermal diffusion of mixtures containing cyclohexane and cyclohexane-d12

Optimum Pressure for Total-Reflux Operated Thermal Diffusion Column for Isotope Separation

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Thermodiffusion in D2-HT und anderen Wasserstoffgemischen

Cited by 55 publications

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Thermal diffusion measurements and simulations of binary mixtures of spherical molecules

Thermal diffusion measurements and simulations of binary mixtures of spherical molecules

Universal isotope effect in thermal diffusion of mixtures containing cyclohexane and cyclohexane-d12

Optimum Pressure for Total-Reflux Operated Thermal Diffusion Column for Isotope Separation

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Thermodiffusion in D_2-HT und anderen Wasserstoffgemischen