Manifestation of Fermi resonance in Raman spectra of micellar aqueous solutions of sodium octanoate

The paper presents the results of an experimental study of the role of the Fermi resonance (FR) between the overtone of the bending and symmetric valence vibrations of the water molecule in micellar solutions of sodium octanoate in the mechanisms of formation of the water valence band. The analysis of broad spectral bands was carried out using genetic algorithms and gradient methods. The frequency detuning between the components of the Fermidoublet for all the samples were obtained at room temperature. For aqueous solutions of sodium octanoate in the critical concentration of micelle formation (0.4 M) frequency detuning ceases to decrease with the growth of surfactant concentration, which is explained by the strengthening of the network of hydrogen bonds in the solution in the process of combining monomers and dimers of surfactants in multimolecular aggregates - micelles. A significant contribution of the Fermi resonance to the intensity of the valence band of water in sodium octanoate solutions was demonstrated. The FR interaction constants were calculated.