ИСТИНА

RALEIGH LIGHT SCATTERING IN PHYSICAL CHEMISTRY OF LIQUIDS AND MIXTURES Durov V.A. Faculty of Chemistry, Moscow State University, Vorobyevy Gory, Moscow 119899, Russia, Е-mail: durov@phys.chem.msu.ru http://www.chem.msu.su/eng/people/durov.html The author’s results [1-7] concerning development of the theory of isotropic and anisotropic fluctuations in liquids and applications to molecular models of integral Raleigh light scattering in liquids and mixtures are discussed. The special attention is paid to the problem of constructing generalized thermodynamic and molecular models of the system with internal variables of various kind and tensor dimension and applications to fluctuations, light scattering and relaxation phenomena. The methods for deriving thermodynamic potentials of the non-equilibrium states of matter characterized by the internal parameters of various nature and tensor dimension have been developed. The expressions for the fluctuating parts of Helmgoltz energy F and Gibbs energy G for the closed systems, as well as the grand thermodynamic potential  for the open non-equilibrium systems were derived [1-2]. Models with discrete and continuous distributions of parameters of state, described by the scalar, vector, and tensor internal parameters are presented. General thermodynamic relationships for the fluctuating anisotropic states of liquids were established. The contributions from fluctuations of internal parameters to thermodynamic properties (heat capacity, compressibility, thermal expansion coefficient, etc.) are discussed. The notion of equilibrium and nonequilibrium (according to internal variables) fluctuations is introduced. It is shown that the fluctuations of extensive variables (energy, entropy, volume) are defined by classic expressions with equilibrium susceptibilities (heat capacity, compressibility), related to the constant thermodynamic affinity of internal process, while the fluctuations of intensive variables (temperature, pressure) are expressed through instant values of susceptibilities, related to constant extent of internal process. The theory of Rayleigh light scattering in relaxing media, taking into account the internal field effects is constructed. The expression for local field for anisotropic states of matter is given [6]. Theory of anisotropic light scattering is constructed taking into account the internal field effects with generalized Lorenz-Lorentz formula for weakly nonequilibrium anisotropic fluctuation states of matter, valid for molecular liquids with molecular polarizability tensors of general form, not only with axial symmetry [8]. The correlation of the density and concentration fluctuations in mixtures was established. The new contributions to Rayleigh light scattering due to fluctuations of the internal parameters were revealed. They can be comparable with the contributions from density fluctuations. The relationship between internal parameters and molecular models of liquid systems is discussed with emphasis on thermodynamic and structural parameters of supramolecular ordering in liquids. The optic correlation factors [1] (similar to Kirkwood dipole correlation factor in the theory of dielectrics [1]) are introduced. They reflect correlations of main axes of polarizability tensors of molecules in liquids. Their relationships with thermodynamic and structural parameters of supramolecular aggregation in nonideal liquid systems are established, for various topologic forms of supramolecular species. The results on modeling supramolecular ordering in molecular mixtures, self-organized by noncovalent molecular interactions like H-bonding are presented in the framework of unified approach for describing and analyzing their thermodynamic, dielectric, optic, and kinetic properties [1-2]. 1. Durov V.A., In Concentrated and Saturated Solutions; A.M. Kutepov, Ed.; Nauka: Moscow, 2002, p.170. (In Russian). 2. Durov V.A. // J. Mol. Liquids 2003, 103-104, 41. 3. Durov V.A. // Pure and Appl. Chem. 2004, 76 (1), 1. 4. Durov V.A. In: Novel Approaches to the Structure and Dynamics of Liquids: Experiments, Theories, and Simulations; / J. Samios, V.A. Durov, Eds. / NATO Science Series. II. Mathematics, Physics and Chemistry. V.133. Dordrecht, Kluwer, 2004, 17-40. 5. Durov V.A. // J. Mol. Liquids 2004, 113, 81. 6. Durov V.A. // Zh. Fiz. Khim. 2005, 79, 9, 1618. 7. Durov V.A. / Durov V.A., Ageev E.P. Thermodynamic Theory of Mixtures. (Monograph in Russian). Editions 1-3. Мoscow: 1987, 2002, 2010. Chapter 7. 8. Kielich S. Molecular Nonlinear Optics, Nauka Publishing Co., 1981. (Translated to Russian, 1981)