Intensity fluctuations of scattered light caused by acoustic phonons in H-bonded liquids

1/f fluctuations are widely observed in various physical, chemical and biomedical systems. T. Musha and G. Borbely took a laser light scattering experiments where 1/f fluctuations directly represent the phonon energy fluctuations. Light scattering experiments for liquids shows that scatterers are not propagating ones such as phonons, but localized ones. Previously it was shown that hydrogen-bonded (H-bonded) liquids have structural heterogeneities of nanometer size (supramolecular ones) which can act as localized scatterers of a light beam. In this work fluctuations of light scattering in H-bonded liquids have been investigated. Power spectral density are describing by law S(f)similar to 1/f(alpha) where index. depends on the type of liquid and molar ratio water/glycerol in solution. Two simple models which can explain this phenomenon are considered. The first model is a one-dimensional chain with nonlinear interaction between atoms, known as the Fermi-Pasta-Ulam system. In such a system there is a transfer of energy among modes, resulting in slow 1/f fluctuations of total energy. In the second model we consider liquids structure by percolation theory which predicts an existence of weak supramolecular heterogeneities. Thus, intensity fluctuations might reflect fluctuations of the cross section scattering centers and/or fluctuations in the number of such centers in the volume of scattering.