Soret effect in forced Rayleigh scattering

Bloisi, F.; Vicari, L.; Cavaliere, P.; Martellucci, S.; Quartieri, J.; Mormile, Pasquale; Pierattini, G.

doi:10.1007/bf00694201

Cited by 23 publications

(9 citation statements)

References 9 publications

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“…26,27,30 The sample is exposed to a holographic interference grating and, due to optical absorption, a temperature grating is formed. Driven by the resulting temperature gradients, thermal diffusion takes place and a concentration grating with the same wave vector as the optical grating builds up.…”

Section: Tdfrsmentioning

confidence: 99%

Collective and thermal diffusion in dilute, semidilute, and concentrated solutions of polystyrene in toluene

Rauch

Köhler

2003

The Journal of Chemical Physics

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Correlation between thermal diffusion and solvent self-diffusion in semidilute and concentrated polymer solutions Thermal and mass diffusion in a semidilute good solvent-polymer solution Collective mass diffusion ͑D͒, thermal diffusion (D T ), and Soret coefficients (S T ) have been determined for solutions of polystyrene in toluene ranging from dilute (10 Ϫ4 g/cm 3 ) to concentrated ͑0.9 g/cm 3 ͒ by a transient holographic grating technique and photon correlation spectroscopy ͑collective diffusion only͒. The molar mass range of the polymer was between 4.75 and 4060 kg/mol. With a slight exception at intermediate concentrations, D T is molar mass independent over the entire concentration range. Above a polymer concentration of CϷ0.2 g/cm 3 the rising glass transition temperature of the solution leads to a rapid slowing down of both mass and thermal diffusion ͑Ludwig Soret effect͒ and the structure relaxation enters the experimental time window.Both D and D T are governed by the same microscopic local viscosity eff , which increases dramatically at T g . It cancels out in S T ϭD T /D. As a consequence, S T is completely insensitive to the glass transition and shows concentration-dependent scaling as expected for a fictive polymer solution with concentration-independent local friction. Where available, results are compared with literature data.

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Section: Tdfrsmentioning

confidence: 99%

Collective and thermal diffusion in dilute, semidilute, and concentrated solutions of polystyrene in toluene

Rauch

Köhler

2003

The Journal of Chemical Physics

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“…is the Heaviside step function, the amplitudes of the thermal and the concentration grating are [ 7,8 ] …”

Section: For An Excitation Pulse S(t)=so[h[tt))-h(t-t_)] Lasting Frmentioning

confidence: 99%

“…The combined phase grating is read by Bragg diffraction of a readotlt laser beam. From the time-dependent diffraction efficiency, the translational diffusion coefficient, the thermal diffusion coefficient, and the Soret coefficient are obtained in a very direct way [7,8].…”

Section: Introductionmentioning

confidence: 99%

Holographic grating study of mass and thermal diffusion of polystyrene/toluene solutions

1995

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The transient grating technique of thermal diffusion forced Rayleigh scattering (TDFRS) has been employed to study translational and thermal diffusion of polystyrene in toluene. Different molar masses and concentrations below or slightly above the overlap concentration c* have been investigated. The translational diflusion coefficients agree well with results obtained from photon correlation spectroscopy. Small remaining differences can be attributed to sample polydispersity. The molar mass independence of the thermal difl'usion coefficient is confimled, and thermal diffusion and Sorer coellicients are compared with data obtained from thermal field flow fractionation and diffusion cell experiments.

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“…Thermodiffusion (also called the Soret effect or Ludwig-Soret effect) is a phenomenon where a mass flow is induced by a gradient of temperature in a complex, at least binary, liquid [1][2][3]; it was observed for the first time almost 150 years ago [1]. The conventional hydrodynamic techniques using a thermodiffusion-flow cell [4,5] were later enriched, for a faster determination of the Soret coefficient (S T ), by using optical methods such as small-angle Rayleigh scattering [6,7], beam deflection [8][9][10], and forced Rayleigh scattering (FRS) [11][12][13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Diffusion and thermodiffusion studies in ferrofluids with a new two-dimensional forced Rayleigh-scattering technique

Demouchy¹,

Mezulis²,

Bée³

et al. 2004

J. Phys. D: Appl. Phys.

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In this paper, we present a new simple two-dimensional forced Rayleigh-scattering (FRS) experimental setup for determination of the nanoparticle-diffusion coefficient (D M) and the Soret coefficient (S T) in colloids. For this purpose, we give a two-timescale model for the evolutions of temperature and colloid concentration (similar to that given for a former one-dimensional FRS method) and a complete description of the signals diffracted by a squared-lattice grating. Both transport properties in ferrofluids (magnetic colloids) determined with this new setup are in good agreement with those found with samples already studied using the one-dimensional technique. This work is completed by studying new samples. Experimental results we obtained confirm and make clearer the following: (i) the strong Soret effect in ferrofluids has a nanoparticle origin and (ii) furthermore, this origin lies in the immediate surroundings of the nanoparticles (ionic or surfacted coating and dispersion liquid).

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Soret effect in forced Rayleigh scattering

Cited by 23 publications

References 9 publications

Collective and thermal diffusion in dilute, semidilute, and concentrated solutions of polystyrene in toluene

Collective and thermal diffusion in dilute, semidilute, and concentrated solutions of polystyrene in toluene

Holographic grating study of mass and thermal diffusion of polystyrene/toluene solutions

Diffusion and thermodiffusion studies in ferrofluids with a new two-dimensional forced Rayleigh-scattering technique

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