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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 32: Poster: Liquids and Ionic Liquids

CPP 32.2: Poster

Wednesday, March 24, 2010, 17:30–19:00, Poster C

Measurement of diffusion and thermal diffusion in ternary mixtures. — •Andreas Königer and Werner Köhler — Physikalisches Institut, Universität Bayreuth

The molecular diffusion process in ternary mixtures is much more complicated than that in binaries, because of additional cross diffusion coefficients.

We have developed a highly sensitive two-color beam deflection technique to measure diffusion and thermal diffusion in ternary fluid mixtures. Simultaneous detection of two laser beams with different wavelengths makes it possible to determine the concentration profile of all three components. By comparing the measured beam deflection signal to a numerical solution of the coupled heat and mass transport equations, the diffusion matrix and the thermal diffusion coefficients can be obtained by a non-linear least squares fitting routine.

We report on first measurements of the Soret-, thermal diffusion, and diffusion coefficients, including cross diffusion, of a mixture consisting of tetralin, dodecane and isobutylbenzene, which are known as reference systems for thermal diffusion in binary mixtures.