The relation between the structure and Far-IR spectra of water

Abstract

The dielectric response of elastic vibrations of water molecules along H bonds is analyzed in terms of the model of harmonic oscillators. It is demonstrated that this response corresponds to the submillimeter wavelength range and the translational band in the far-IR spectral range. The spectra of permittivity of light and heavy water are analytically calculated in a wide spectral range (0–1000 cm−1) of the orientational-translational relaxation containing the microwave Debye and far-IR librational bands in addition to the aforementioned bands. For the far-IR librational band, the librational motion of rigid dipoles in a relatively narrow and deep hatpotential well is considered. The molecular configurations that allow such librations are schematically presented. A concept that establishes a relation between the dielectric properties of water and the proton hopping from one H-bonded molecule to another is proposed.