Using the thermodynamic expression for the Soret coefficient for diluted mixtures, expressed through the temperature derivative of the molecule chemical potential at the constant pressure, statistical mechanics is applied to relate this expression to the microscopic molecular parameters. When the contribution of the internal degrees of freedom in molecules is accounted for in the calculations, the results are equivalent to previous approaches, adding new terms to the Soret coefficient. These terms are related to the differences in molecular vibration and rotation between the solute and solvent molecules. These “internal” contributions to molecular thermodiffusion explain the isotopic effect observed in molecular systems. The theory describes most of the experimental data on the thermodiffusion of isolated molecules placed in non-electrolyte liquids. The approach also reveals a strong dependence of molecular thermodiffusion on molecular symmetry.
Semen N. Semenov 1; Martin E. Schimpf 2
@article{CRMECA_2011__339_5_335_0,
author = {Semen N. Semenov and Martin E. Schimpf},
title = {Internal degrees of freedom, molecular symmetry and thermodiffusion},
journal = {Comptes Rendus. M\'ecanique},
pages = {335--341},
publisher = {Elsevier},
volume = {339},
number = {5},
year = {2011},
doi = {10.1016/j.crme.2011.03.011},
language = {en},
}
Semen N. Semenov; Martin E. Schimpf. Internal degrees of freedom, molecular symmetry and thermodiffusion. Comptes Rendus. Mécanique, Thermodiffusion and coupled phenomena, Volume 339 (2011) no. 5, pp. 335-341. doi : 10.1016/j.crme.2011.03.011. https://comptes-rendus.academie-sciences.fr/mecanique/articles/10.1016/j.crme.2011.03.011/
[1] Thermodynamics of Irreversible Processes, North-Holland Publishing Company, Amsterdam, 1952
[2] Non-Equilibrium Thermodynamics, North-Holland, Amsterdam, 1962
[3] Modern Thermodynamics, Wiley, New York, 1999
[4] The 2H thermal diffusion isotope effect in benzene and methanol, J. Chem. Phys., Volume 78 (1983), p. 7010
[5] Effect of mass distribution on the isotopic thermal diffusion of benzene, J. Chem. Phys., Volume 86 (1987), p. 5217
[6] Separation of isotopically substituted liquids in the thermal diffusion column, J. Chem. Phys., Volume 59 (1973), p. 6061
[7] Effect of carbon and hydrogen isotopic substitutions on the thermal diffusion of benzene, J. Chem. Phys., Volume 90 (1989), p. 602
[8] Effect of mass distribution on the isotopic thermal diffusion of substituted benzenes, J. Chem. Phys., Volume 81 (1984), p. 6136
[9] Isotopic thermal diffusion of carbon disulfide in the liquid phase, J. Chem. Phys., Volume 86 (1987), p. 397
[10] Thermodiffusion in D2-HT und anderen Wasserstoffgemischen, Z. Naturforsch., Volume 16A (1960), p. 133
[11] Handbuch der Physik (S. Flügge, ed.), Springer, Berlin, 1958, p. 12
[12] Thermal Nonequilibrium Phenomena in Fluid Mixtures (W. Köhler; S. Wiegand, eds.), Springer, Heidelberg, 2002
[13] On the molecular mechanism of thermal diffusion in liquids, Mol. Phys., Volume 80 (1993), p. 1389
[14] On the nature of thermal diffusion in binary Lennard-Jones liquids, J. Chem. Phys., Volume 112 (2000), p. 2436
[15] The influence of interaction details on the thermal diffusion in binary Lennard-Jones liquids, J. Chem. Phys., Volume 115 (2001), p. 8978
[16] Thermal diffusion sensitivity to the molecular parameters of a binary equimolar mixture, a non-equilibrium molecular dynamics approach, Fluid Phase Equil., Volume 208 (2003), p. 171
[17] On thermal diffusion in binary and ternary mixtures by nonequilibrium molecular dynamics, Philos. Mag., Volume 83 (2003), p. 2097
[18] Molecular origin of thermal diffusion in benzene + cyclohexane mixtures, Phys. Rev. Lett., Volume 87 (2001), p. 055901
[19] Universal isotope effect in thermal diffusion of mixtures containing cyclohexane and cyclohexane-d12, J. Chem. Phys., Volume 123 (2005), p. 014506
[20] Statistical thermodynamic expression for the Soret coefficient, EPL, Volume 90 (2010), p. 56002
[21] On thermodynamic approach to mass transport, Thermal Nonequilibrium, Lecture Notes of 8th International Meeting on Thermodiffusion, 2008, pp. 109-116 (ISBN: 978-3-89336-523-4)
[22] Mass transport thermodynamics in nonisothermal molecular liquid mixtures, Phys. Usp., Volume 52 (2009), p. 1045
[23] Thermodiffusion of charged colloids: Single-particle diffusion, Langmuir, Volume 23 (2007), p. 1674
[24] The radial distribution function in liquids, J. Chem. Phys., Volume 10 (1942), p. 394
[25] Statistical Theory of Liquids, Chicago Univ., 1964
[26] Statistical Physics (E.M. Lifshitz; L.P. Pitaevskii, eds.), Pergamon Press, 1980 (Part 1, Chapter IV, English translation)
[27] Colloid transport in non-uniform temperature, Phys. Rev. E, Volume 67 (2003), p. 011404
[28] Colloid thermophoresis as a non-proportional response, J. Non-Equil. Thermodyn., Volume 32 (2007), p. 221
[29] Thermodiffusion of charged micelles, Phys. Rev. Lett., Volume 95 (2005), p. 208301
[30] Symmetric diffusion equations, barodiffusion, and cross-diffusion in concentrated liquid mixtures, Phys. Rev. E, Volume 70 (2004), p. 031202
[31] Molecular thermodiffusion (thermophoresis) in liquid mixtures, Phys. Rev. E, Volume 72 (2005), p. 041202
[32] Mechanism of polymer thermophoresis in nonaqueous solvents, J. Phys. Chem. B, Volume 104 (2000), p. 9935
[33] Order and disorder in liquid solutions, J. Phys. Chem., Volume 43 (1939), p. 97
[34] Colloid transport by interfacial forces, Annu. Rev. Fluid Mech., Volume 21 (1989), p. 61
[35] Thermophoresis of metal particles in a liquid, J. Colloid Interface Sci., Volume 176 (1995), p. 454
[36] Particle thermophoresis in liquids, Eur. Phys. J., Volume 15 (2004), p. 255
[37] Statistical Physics (E.M. Lifshitz; L.P. Pitaevskii, eds.), Pergamon Press, 1980 (Part 1, Chapter IX, English translation)
[38] Colloidal Systems and Interfaces, Wiley, New York, 1988
[39] Soret effect of flexible macromolecules, C. R. Seances Acad. Sci., Ser. 2, Volume 293 (1981), p. 1025
[40] The “macromolecular tourist”: universal temperature dependence of thermal diffusion in aqueous colloidal suspensions, Eur. Phys. J. E, Volume 19 (2006), p. 59
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