Direct measurement of thermophoretic forces

Helden, Laurent; Eichhorn, Ralf; Bechinger, Clemens

Direct measurement of thermophoretic forces

Dateien

Helden_0-410873.pdfGröße: 661.05 KBDownloads: 252

Datum

2015

Autor:innen

Helden, Laurent

Eichhorn, Ralf

Bechinger, Clemens

Open Access-Veröffentlichung

Open Access Hybrid

Sammlungen

Physik

Publikationstyp

Zeitschriftenartikel

Publikationsstatus

Published

Erschienen in

Soft matter. 2015, 11(12), pp. 2379-2386. ISSN 1744-683X. eISSN 1744-6848. Available under: doi: 10.1039/c4sm02833c

Zusammenfassung

We study the thermophoretic motion of a micron sized single colloidal particle in front of a flat wall by evanescent light scattering. To quantify thermophoretic effects we analyse the nonequilibrium steady state (NESS) of the particle in a constant temperature gradient perpendicular to the confining walls. We propose to determine thermophoretic forces from a "generalized potential" associated with the probability distribution of the particle position in the NESS. Experimentally we demonstrate, how this spatial probability distribution is measured and how thermophoretic forces can be extracted with 10 fN resolution. By varying temperature gradient and ambient temperature, the temperature dependence of Soret coefficient ST(T) is determined for r = 2.5 μm polystyrene and r = 1.35 μm melamine particles. The functional form of ST(T) is in good agreement with findings for smaller colloids. In addition, we measure and discuss hydrodynamic effects in the confined geometry. The theoretical and experimental technique proposed here extends thermophoresis measurements to so far inaccessible particle sizes and particle solvent combinations.

Fachgebiet (DDC)

530 Physik

Zitieren

ISO 690

HELDEN, Laurent, Ralf EICHHORN, Clemens BECHINGER, 2015. Direct measurement of thermophoretic forces. In: Soft matter. 2015, 11(12), pp. 2379-2386. ISSN 1744-683X. eISSN 1744-6848. Available under: doi: 10.1039/c4sm02833c

BibTex

@article{Helden2015-03-28Direc-39262,
  year={2015},
  doi={10.1039/c4sm02833c},
  title={Direct measurement of thermophoretic forces},
  number={12},
  volume={11},
  issn={1744-683X},
  journal={Soft matter},
  pages={2379--2386},
  author={Helden, Laurent and Eichhorn, Ralf and Bechinger, Clemens}
}

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