Microheterogeneous systems solute distribution

In general, the chemical potential of the solution in the micellar phase must equal that in the surrounding aqueous medium when thermodynamic equilibrium is established. Nonpolar solutes, such as the permanent gases, which do not interact strongly with either phase may be distributed rather evenly over the whole microheterogeneous system (39). On the other hand, typical electrolytes are practically restricted to the aqueous medium, while molecules of hydrophobic substances, e.g. hydrocarbons, are almost totally sequestered in the micelles. 

The IGTT model and its many elaborations have been widely used in studies of microheterogeneous systems. The model is based on the stochastic distribution of probes and quenchers over the confinements. Before discussing it, however, we approach the problem from the aspect of diffusion-limited reactions and consider how a change from a homogeneous three-dimensional (3-D) solution into effectively 2-D, 1-D, and 0-D systems (with 0-D we refer to a system limited in all three dimensions such as a spherical micelle) will affect the diffusion-controlled deactivation process. The stochastic methods apply only to the zero-dimensional systems we present some of the elaborations of the IGTT model with particular relevance to microemulsion systems and the complications that arise therein. We then review and discuss some of the experimental studies. It appears as if much more could be done with microemulsions, but the standard methods from studies of normal micelles have to be used with utmost care. 

Diverse investigations of the miscellaneous ternary systems Sn-Pb-Cd, Sn-Ga-In, Sn-Sb-Bi, " Pb-In-Sb, and Pb-Bi-Hg have been undertaken by a number of Russian authors. It was concluded from the results of an ultrasonic study of Sn-Pb-Cd liquid solutions that intermetallic compounds are not formed in this system. Thermodynamic analysis of the Sn-Sb-Bi system shows both positive and negative deviations from ideality in the liquid state.Finally, interpretation of the atomic distribution functions of Pb-In-Sb solutions has led to the conclusion that the melts have a microheterogeneous structure in the fusion... 

In this article we shall focus on recent work involving dilute aqueous surfactant solutions. As a background the thermodynamics and statistics of these solutions will be discussed first (Section II). The distribution of substrate molecules in microheterogeneous solution is considered in Section m. It is decisive for the kinetics of elementary photochemical reactions (Section IV), which depend on the peculiar colloidal solution structure. Effects of the microscopic environments on photochemical reactions are treated in Section V. Finally, the use of known photochemical systems as probes for studying details of the structure of surfactant solutions will be considered in Section VI. 

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