In this paper, a new method for analyzing certain physical and chemical properties of liquid water near surfaces is described. "Probe" molecules are dissolved in the water system and are excited by a short laser pulse. The ability of the probe to undergo a fast nonradiative process depends on a reorientational relaxation time of the water solvent, which may become orders of magnitude slower for water near a surface. Using timeresolved methods and a sufficiently fast probe, one can observe a direct dynamic competition between diffusion of the probe and the nonradiative event. Thus, in principle, it is possible to obtain both these rates as a function of distance from a surface. The methods can be applied to a variety of surfaces. Here, they are used to investigate the small biologically relevant water pools in sodium bis(2-ethylhexy1)sulfosuccinate (AOT) reverse micelles, whose surfaces are highly hydrophilic. Perturbations on the translational velocity autocorrelation function of the probe, as measured by the diffusion fluxes, are very large, extending nearly to the center of the largest micelle studied (radius -55 A). On the other hand, perturbations on the orientation relaxation of the solvent, as measured by the probe fluorescence lifetimes, were found to extend no more than -10-15 A from the surface of any of the micelles studied.

Palffy-Muhoray, P.; Mustafa, M.; and Kyu, Thein, "Polymerization-Induced Phase-Separation in a Liquid-Crystal-Polymer Mixture" (1993). College of Polymer Science and Polymer Engineering. 68.We have used light scattering to study the kinetics of polymerization-induced phase separation in a liquid-crystal-polymer mixture. The evolution of the structure factor is compared with scaling predictions for thermally quenched systems. We have also observed a cascading phenomenon where phase separated domains become unstable and undergo phase separation for a second time.