Data by NMR and Representations of Self-Diffusion Coefficients in Carbon Tetrafluoride and the Determination of Intermolecular Force Constants

Khoury, Fouad; Kobayashi, Riki

doi:10.1063/1.1676430

Cited by 28 publications

(6 citation statements)

References 15 publications

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“…60 The experimental initial slopes for other substances are, in general, slightly negative or almost zero. [22][23][24][25][26][30][31][32][33] On the other hand, the Enskog theory for hard spheres at higher densities gives a much more negative slope than the present. 3 Here we test whether the density dependence of D / ͱ T can be accounted for or not in analogy with the Enskog theory in terms of g͑͒.…”

Section: Density Dependence Of the Self-diffusion At Low Densitiescontrasting

confidence: 53%

“…Self-diffusion coefficients have been determined for various supercritical fluids and gases by the van der Waals laboratory group, [22][23][24] Kobayashi and co-workers, 25,26 Jonas and co-workers, 18,27 and Asahi and Nakamura 28,29 using the PGSE method. Peereboom et al found that the initial slope of D for xenon is almost zero, in contrast to the prediction of the strongly negative slope by the Enskog theory for dense gases.…”

Section: Introductionmentioning

confidence: 99%

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Self-diffusion of supercritical water in extremely low-density region

Yoshida

Matubayasi

Nakahara

2006

The Journal of Chemical Physics

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The self-diffusion coefficient D for super- and subcritical water is determined by using the proton pulsed-field-gradient spin echo method at high temperatures and low densities. The density of water is ranged in the steamlike region from 0.0041 to 0.0564 g [corrected] cm(-3) at a supercritical temperature of 400 degrees C, also at 0.0041-0.0079 and 0.0041-0.0462 g [corrected] cm(-3) (the steam-branch densities on the coexistence curve and lower) at 200 and 300 degrees C, respectively. The density is precisely determined on the basis of the PVT dependence of the proton chemical shift. The density-diffusivity products in the zero-density limit divided by the square root of the temperature, (rho D)0/square root of T, are 0.94, 1.17, and 1.35 mg m(-1) s(-1) K(-1/2) (mg=10(-3)g) [corrected] at 200, 300, and 400 degrees C, respectively. The (rhoD)0/square root of T obtained decreases with decreasing temperature and is significantly smaller than the temperature-independent value from the hard sphere model, 1.95 mg [corrected] m(-1) s(-1) K(-1/2). The marked temperature dependence reflects the presence of the strong attractive interaction between a pair of water molecules. The magnitude of the experimental D values and the temperature dependence are well reproduced by the molecular dynamics simulation using TIP4P-FQ model. The initial slope of the product rhoD/square root of T against rho is slightly negative at 300 and 400 [corrected] degrees C.

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Section: Density Dependence Of the Self-diffusion At Low Densitiescontrasting

confidence: 53%

Section: Introductionmentioning

confidence: 99%

Self-diffusion of supercritical water in extremely low-density region

Yoshida

Matubayasi

Nakahara

2006

The Journal of Chemical Physics

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“…The accuracy in the values of 11 is dependent on the accuracy in the knowledge of G , that is usually estimated in four ways: − (i) theoretically, from the known dimensions, geometry, number of turns of wire in the coil, and current applied; (ii) by measuring the changes in the magnetic field when a small sample (commonly, water) is placed at different locations; (iii) by calibration (Cal) with a substance of known self-diffusion; and (iv) by the shape of the spin echo after the 90° pulse, which for cylindrical probes is related to the first-order Bessel function. Dawson et al and Khoury et al cited the use of a “flux-gate magnetometer” for this task by a procedure which is very close to the second way; that is, the apparatus indicates the values of the magnetic field along the axis of coils, and G is calculated with these data. For the methods of Burnett and Harmon and Barbe et al, the determination of G is not required.…”

Section: Methodsmentioning

confidence: 99%

“…In the case of carbon tetrafluoride, where only two sets of supercritical points are available, it is not possible to know which are correct, since those of Khoury and Kobayashi 284 are systematically (20 to 40) % lower than those of Has and Ludemann. 291 For hydrogen, the neutron scattering 551 produced results (5 to 10) % higher than the spin−echo technique, 419 the former being in better agreement with the low-density tracer diffusivities than the latter.…”

Section: General Considerationsmentioning

confidence: 99%

Self-Diffusion in Molecular Fluids and Noble Gases: Available Data

et al. 2015

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Experimental self-diffusivities of gases, vapors, and liquids obtained by means of tracer techniques and nuclear magnetic resonance are reviewed. The considered substances range from noble gases and simple diatomics (nitrogen, oxygen, carbon monoxide, etc.) to complex organic molecules, such as phenolphthalein dimethyl ether and 2-(α-methylbenzylamino)-5-nitropyridine, although polymers have not been included. Some comments on the applicability of neutron scattering to the determination of self-diffusion coefficients are also made. All the experimental results of the investigated systems are given as Supporting Information, whereas the references, temperatures, and pressures of these data and the main features of the measurement methods are compiled and classified.

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“…A number of functions have been proposed to fit the self-diffusion coefficient data. They have been applied and tested for a variety of gases and liquids. − The fitting functions can be categorized into the following types; (i) the Arrhenius type, − ,,,,, (ii) the scaling to the hard-sphere model, ,,,− ,− (iii) the simple hydrodynamic model or modified ones, ,− ,,,,,,, (iv) the molar-volume type, , (v) explicit terms of density and temperature, ,, (vi) the density expansion type, ,− and (vii) the gas kinetic theory with collision integrals. ,,,,,,− The choice of the fitting function is based on the region of the thermodynamic states in which the function can appropriately represent the temperature and density dependencies of the self-diffusion coefficients. Some of them are based on physical concepts or meaning, but some others are simply phenomenological models.…”

Section: Introductionmentioning

confidence: 99%

Scaled Polynomial Expression for Self-Diffusion Coefficients for Water, Benzene, and Cyclohexane over a Wide Range of Temperatures and Densities

et al. 2010

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Self-diffusion coefficients D for water, benzene, and cyclohexane were determined in high-temperature conditions along the liquid branch of the coexistence curve and in supercritical conditions including an extremely low density region. The diffusion data available in literature were compared and evaluated. A fifth-order polynomial for ln D with the single variable T −1 (ln(D/10−9 m2·s−1) = a 0+ a 1 x + a 2 x 2 + a 3 x 3 + a 4 x 4 + a 5 x 5 with x = 1000/(T/K)) was found to provide good fitting along the liquid branch of the coexistence curve. A single polynomial function for the scaled quantity ρD/T 1/2 with the two variables, density ρ and temperature T −1 (third-order polynomial of ρ and T −1 and the cross terms), can universally represent the diffusion data over a wider range including both the gas−liquid coexistence and the extremely low density conditions. The function gives a reliable and reasonable behavior of D in the medium-density supercritical states in which the experimental uncertainty is rather large due to the severe conditions. The temperature and density differentials thus obtained were used to shed light on the effect of hydrogen bonding that makes water different from nonpolar organic liquids. The temperature dependence of the self-diffusion coefficient for water is larger than those for organic liquids, due to the large contribution of the attractive hydrogen-bonding interaction. The density dependence is larger for organic liquids than that for water.

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Data by NMR and Representations of Self-Diffusion Coefficients in Carbon Tetrafluoride and the Determination of Intermolecular Force Constants

Cited by 28 publications

References 15 publications

Self-diffusion of supercritical water in extremely low-density region

Self-diffusion of supercritical water in extremely low-density region

Self-Diffusion in Molecular Fluids and Noble Gases: Available Data

Scaled Polynomial Expression for Self-Diffusion Coefficients for Water, Benzene, and Cyclohexane over a Wide Range of Temperatures and Densities

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