Regensburg 2013 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 20: Poster: Colloids and Complex Liquids
CPP 20.9: Poster
Tuesday, March 12, 2013, 18:15–20:15, Poster C
A multicolor interferometer for the simultaneous measurement of contrast factors — •Thomas Triller and Werner Köhler — Physikalisches Institut, Universität Bayreuth, 95440 Bayreuth, Germany
During the last years thermodiffusion in ternary fluid mixtures has been the subject of gaining interest.
Currently, optical experiments are performed both in a microgravity environment on board of the international
space station (ISS) using an interferometric device (SODI) and on ground using the beamdeflection technique
[1]. These experiments make use of a change in the refractive index n to analyse changes in the concentration of the mixtures.
To interpret the data, a precise knowledge of the so called contrast factors (∂ n / ∂ ci)p,T,cj≠ i and (∂ n / ∂ T)p,ci is essential. Monte Carlo simulations have shown that errors in the refractive index need to be as low as 10−5 to get reliable values for the Soret coefficients.
As a step to reach such precision, we present a new setup capable of measuring contrast factors at five different wavelengths simultaneously. The basic outline consists of a Michelson-Interferometer with a special sample cell.
[1] Königer, A., Wunderlich, H. and Köhler, W., J. Chem. Phys, 132, pp. 174506, 2010.