Vibrational Dynamics in Liquid Water: A New Interpretation of the Infrared Spectrum of the Liquid

Abstract

In comparing the infrared spectra of liquid water and simple hydrates, two anomalies are noted which are apparently inexplicable in terms of presently acceptable theories of the liquid. These anomalies are explained in terms of a Maxwellian distribution of collisional interactions between water molecules, which when put in quantitative form reveals (1) that most molecules in the liquid are highly distorted by collisional perturbations, and (2) that there is a broad distribution of distortion among the molecules in the liquid. When translated into vibrational dynamics, these concepts lead to a continuum distribution of ν 1 and ν 3 modes of varying distorted molecules. It is shown that in its stretching motion, liquid water behaves dynamically as a continuum of OH bond oscillators of different frequencies, demonstrating both weak inter‐ and intramolecular vibrational interactions. A new interpretation of the infrared spectrum of liquid water is given in terms of this model, and other spectral evidence is offered in support of it.