Depolarized light scattering of heavy water, and hydrogen bond dynamics

Abstract

We measured the depolarized Rayleigh scattering of heavy water from 70°C down to -13°C. The spectra were analysed and show a low frequency component. Both the intensity and the width of this line are temperature dependent. The characteristic time associated with the width has an Arrhenius behaviour with an activation energy of 2·5 kcal mol^-1. The intensity has a quadratic shape with a maximum around 50°C. We interpret these results as a manifestation of the hydrogen-bond dynamics and propose a mechanism for the breaking of H-bonds through the librational movements. Comparisons are made with theoretical models and molecular dynamics simulations.