Development of optical digital interferometry technique for measurement of thermodiffusion coefficients

The paper presents the development of an experimental technique based on optical digital interferometry for measuring thermodiffusion (Soret) coefficients. The experiments are performed in a cubic cell containing an aqueous solution and being heated from above. This is the first report on the method that allows to record the temperature and concentration fields in the entire cell rather than just between two points. Such information is not only available at the steady state, but within the whole diffusion process. The time-dependent evolution of the concentration field allows the measurement of molecular diffusion coefficient in addition to the Soret coefficients. The measurements of transport coefficients have been performed in water/ethanol mixture and water/isopropanol mixtures.