Diffusion-Oscillatory Dynamics in Liquid Water on Data of Dielectric Spectroscopy

TL;DR

This paper presents a new model linking dielectric spectroscopy data of liquid water to its molecular dynamics, revealing characteristic relaxation times and challenging previous assumptions about water molecule lifetimes.

Contribution

The study introduces a novel model connecting water's dielectric relaxation features to molecular diffusion and oscillation dynamics, providing new insights into proton mobility and water ion lifetimes.

Findings

Identifies relaxation times of 50 ps and 3 ps for water molecules and ions.

Links dielectric relaxation features to infrared absorption at 180 cm-1.

Questions the long 10-hour lifetime of water molecules.

Abstract

When analyzing the broadband absorption spectrum of liquid water (10^10 - 10^13 Hz), we find its relaxation-resonance features to be an indication of Frenkel's translation-oscillation motion of particles, which is fundamentally inherent to liquids. We have developed a model of water structure, of which the dynamics is due to diffusion of particles, neutral H2O molecules and H3O+ and OH- ions - with their periodic localizations and mutual transformations. This model establishes for the first time a link between the dc conductivity, the Debye and the high frequency sub-Debye relaxations and the infrared absorption peak at 180 cm-1. The model reveals the characteristic times of the relaxations, 50 ps and 3 ps, as the lifetimes of water molecules and water ions, respectively. The model sheds light on the anomalous mobility of a proton and casts doubt on the long lifetime of a water molecule, 10 hours, commonly associated with autoionization.