Experimental approaches to study thermodiffusion – A review

A detailed review of the experimental investigations of the thermodiffusion/thermophoresis process in liquid and gaseous mixtures is presented. Experiments in the laboratories on earth as well as studies in a microgravity environment in space have been described. The former include the non-optical apparatus such as the classical Soret cell, thermodiffusion column, two-chamber thermodiffusion cell and the thermal field-flow fractionation, as well as the optical techniques, viz., classical Soret cell with beam deflection, thermal diffusion forced Rayleigh scattering, thermal lens method and the microfluidic fluorescence method. These methods are discussed along with their advantages and disadvantages. Experiments performed in the microgravity environment are also discussed.