Theoretical calculations of low-frequency spectra, due to intermolecular collective modes in liquid benzene, are presented. The molecules in a liquid are assumed to be organized in instantaneous, quasicrystalline, short-range structures of the lifetime of order of 10−13 s, which perform rotational and translational vibrations. Those vibrations are responsible for the intermolecular part of the femtosecond optical Kerr effect response. The spectra, obtained for five different temperatures, show a good agreement with the experimental results of other authors. We prove that the low-frequency feature of the spectrum, which is evidently augmented at low temperatures, is associated with collective translational intermolecular vibrations.

Herewith we present the results of our studies on the effect of confinement on the solvation of ethyl alcohol in aqueous solutions using Raman spectroscopy of the O-H stretching band. Based on Gaussian-Lorentzian deconvolution of the O-H band Raman spectra we investigate the local structures created between water-water, water-alcohol, and alcohol-alcohol molecules, which are directly related to the solubility of the liquids. Comparison of the responses in bulk solutions and in solutions confined in the pores of the gelatin gel shows that for high ethanol concentrations solubility significantly increases with decrease of the pore sizes.

The evolution of water structure during the gelation process is examined in aqueous solution of agarose using Raman spectroscopy of the O-H stretching band. The measurements have been performed at room temperature for different concentrations of agarose, which yields different dimensions of nanopores in the network of the created gel. Our results show that water confined in the gel pores exhibits evident changes in the local order of molecules in comparison with bulk water and water in the sol state. During the sol-gel transition the number of molecules that participate in the regular tetrahedral H-bond structure increases, and the effect is stronger for higher concentration of the biopolymer.

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A theoretical model of ultrafast dynamics in the optical Kerr effect in molecular liquids is developed. It assumes that for short times there exist dynamic quasicrystalline structures including a central molecule and its nearest neighbors. The interaction of such structures with a femtosecond laser pulse leads to excitation of vibrational modes (local phonons) which are responsible for subpicosecond nonlinear polarizability of the liquid. The results of numerical calculations performed for benzene show a very good agreement with the experimental data. The lifetime of the dynamic quasicrystalline structures in benzene, at room temperature, is estimated to be about 200 fs.