Dresden 2014 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 17: Transport and Confinement I
CPP 17.2: Talk
Tuesday, April 1, 2014, 10:00–10:15, ZEU 260
Direct measurement of thermophoretic forces — •Laurent Helden1 und Clemens Bechinger1,2 — 12. Physikalisches Institut, University of Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart, Germany — 2Max Planck Institut for Intelligent Systems, Heisenbergstr. 3, 70569 Stuttgart, Germany.
Thermophretic motion of colloidal particles is ubiquitous in nature where ever temperature gradients occur. In spite of this the exact mechanism of thermophoretic motion is not jet fully understood and even preeminent features like the size dependence of Soret coefficient are still under debate.
In this context we present a new strategy to directly measure thermophoretic forces. Using total internal reflection microscopy (TIRM) we observe the motion of a single polystyrene particle in a narrow slit subjected to temperature gradients. With increasing gradient a preference of the cold side is observed. Implications for the theoretical description of thermophoresis are discussed.