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ISSN 2071-0186   Ukr. J. Phys. 2015, Vol. 60, N 8, p.782-794
doi:10.15407/ujpe60.08.0782    Paper

Gotsulskiy V.Ya.1,2, Chechko V.E.2, Melnik Yu.A.2

1 Taras Shevchenko National University of Kyiv, Faculty of Physics, Chair of Molecular Physics
(2, Prosp. Academician Glushkov, Kyiv 03022, Ukraine)
2 I.I. Mechnikov National University of Odesa, Faculty of Physics
(2, Dvoryanska Str., Odesa 65026, Ukraine; e-mail: vygot@onu.edu.ua)

The Origin of Light Scattering by Aqueous Solutions of Alcohols In Vicinities Of Their Singular Points

Section: Soft matter
Language: Ukrainian

Abstract: The physical nature of the anomalous peak observed in a vicinity of the singular point in molecular light scattering spectra of diluted aqueous alcohol solutions is analyzed. The singular point corresponds to an unstable state of the solution, in which water molecules are distributed in monolayers around the alcohol molecules. In a vicinity of the singular point, the solution is shown to become inhomogeneous on nano- and mesoscales. Spatial inhomogeneities are formed by two phases, which are similar by their properties, and the phases transitions between them have a fluctuation character. The process of slow establishment of the equilibrium state in aqueous alcohol solutions (for days and longer) is explained by the similarity of thermodynamic properties of those phases. Using the dynamic light scattering, it is shown that if the solution in the equilibrium state is mechanically excited, the character of relaxation has a periodic component, which corresponds to the transitions between the indicated phases. The summation of two peaks associated with independent light scattering in two mesophases makes the anomalous peak of light scattering asymmetric.

Key words: aqueous alcohol solutions, singular point, equilibrium state, fluctuations.