What is liquid water?

Abstract

Recent flash-photolysis experiments on ultrafast timescales have revealed the existence of special structural constraints on water as a solvent for small ions, such as electrons, protons and OH^–. Forming these structures requires molecular reorientational motions with little O-atom movement. An earlier paper outlined the manner by which dynamical motions in pure water are related to anomalous thermodynamic functions through an effective partition function. Cooperativity within the hydrogen-bonding network causes a lowering with increasing temperature of the effective hindering potential for rotations of individual water molecules in liquid water. This hindering potential provides a quantitative measure of distorted H-bond structure in liquid water. In this way, properties of this interesting substance, from the deep supercooled regime to the normal boiling point, can be understood and quantitatively inter-related.