Experimental Lab on Fluctuational Phenomena in Complex Fluids

There exists currently considerable interest in the nature of fluctuations in fluid mixtures driven away from thermal equilibrium by imposing a temperature gradient. An interesting feature is that under such nonequilibrium conditions all fluctuations become long-range. We are studying these fluctuations by observing the static and dynamic properties of laser light scattered from such fluids out of thermal equilibrium. Optical experiments for studying mass diffusion and chemical diffusion processes in liquid mixtures and polymer solutions are being pursued. An experimental program is carried out for measuring transport properties, like viscosity and Soret coefficients of complex fluids and fluid mixtures.

Laser photon-correlation spectroscopy (PCS) is an innovative technique to measure many characteristics of fluids: diffusion coefficient, thermal diffusivity, viscosity and compressibility. This method is especially powerful for near-critical fluids for which the size and life time of fluctuations can be easily measured, and for colloidal, biological and other disperse systems if the particles suspended in the liquid are too small to be detected by optical microscopy. PCS allows one to monitor the growth of the particles during a particular chemical or physico-chermical process and study the kinetics of the process.

Light Scattering Tools

Photon-Correlation Spectrometer PHOTOCOR Complex

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