ABSTRACT
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1 Introduction
When a temperature difference is applied across a binary liquid mixture or solution, a net flow of matter of either component is observed across a plane perpendicular to the direction of the temperature gradient. The de mixing of the liquid eventually comes to a rest when the temperature driven flow is balanced by the Fickian diffusive flow, which is driven by the built up concentration gradient. This transport mechanism is termed thermal diffusion or Ludwig-Soret effect. It was first discovered in 1853 by Lud wig1 and later investigated by Soret on electrolyte solutions.2 The Soret coefficient S T is a measure for the strength of the effect in a given binary liquid. Over the years, thermal diffusion has attracted the interest of re searchers, who were either interested in the physics of the effect itself or who wanted to take advantage from it for, e.g., polymer fractionation.
