Slynchak O. Peculiarities of concentration fluctuations in dilute water-alcohol solutions

The Thesis is devoted to the discussion of the structure, equation of states and the character of fluctuations in dilute water-alcohol solutions. It is proposed that 2-3 molecules of alcohol and about 10 molecules of water form a stable enough molecular complex, called by an elementary cluster (pseudo-particle). In some range of states a system is considered as a mixture of pseudo-particles and water. Its properties are modeled by the van der Waals equation of state. The character of interaction between different clusters is analyzed in details. The anomalous increasing of concentration fluctuations in a system and molecular light scattering is connected with approaching its left pseudospinodal. The concentration dependencies of the Landau-Placzek ratio for water-glycerol and water-gamma-picolin solutions are investigated. It is shown, that maximal increase of concentration fluctuations is observed near inaccessible pseudo-critical points: upper pseudo-critical point in water-glycerol solutions and lower one in water-gamma-picolin solutions. The behavior of the self-diffusion coefficient of water molecules and its collective part for dilute water-etanol solutions is also discussed in the Thesis. Peculiarities of the sound spreading in water-gamma-picolin solutions are analyzed in the vicinity of their peculiar points.