Study of the Properties of an Aqueous Solution of Polar Organics at a Specific Point in Experiments on Measuring the Adiabatic Compressibility and on Dynamic Light Scattering

The results of temperature and concentration experimental studies of the intensity ratio in the scattered light fine structure components (Landau–Placzek ratio) in γ-picoline aqueous solutions are presented. A significant increase in the Landau–Placzek ratio is revealed in a narrow concentration range near the so-called specific point. The specific point corresponds to the polar organic solvent concentration at which formation of molecular aggregates of water and organic component occurs. The sizes of these aggregates were estimated in experiments on measuring the adiabatic compressibility and on dynamic light scattering; the results of measurements according to these independent techniques are in very good agreement. It is concluded that the technique based on measuring the adiabatic compressibility in the gigahertz range of sound frequencies is efficient for estimating the sizes of spatial inhomogeneities at the specific point.