Properties for the spectral parameters of intermolecular vibrations obtained using Raman scattering of light in dilute aqueous solutions of hydrogen peroxide and in the water

Abstract

The spectra of Raman scattering (in the region 4-350 cm-1) of dilute aqueous solutions of hydrogen peroxide in a wide range of concentrations (from 3 to 0.024%), were measured. The spectral parameters of the high-frequency band of intermolecular (longitudinal) vibrations, obtained using the previously proposed approximating function, were analyzed. To do this, the spectral parameters of the band (for each experiment) were plotted on a diagram in which the abscissa axis is the square of the band width, and the ordinate axis is the square of the band frequency. Previously, it was shown that in such coordinates the water points are located in two regions separated by an inclined strip, in which spectral points (frequency gap) are practically absent. For points of hydrogen peroxide solutions with a concentration from 3 to 0.33%, all points are grouped near the straight line approximating them and are located below this frequency gap. For a series with extended range of peroxide concentrations from 3 to 0.024%, the scatter of points from the approximating straight line increases, but also most of the points are located below the gap. Of the rest of points, several points are near the edge of the gap, some of them are inside the gap, but the gap remains. It has been suggested that the presence of this gap is due to the fact that in the liquid phase some of the water molecules are bound to four neighbors, while the remaining molecules are bound to a smaller number of neighbors. Keywords: Raman scattering, hydrogen peroxide, water, intermolecular vibrations, high-frequency band, inhomogeneous distribution, frequency gap, destruction of high-frequency states.