Observation of non-local dielectric relaxation in glycerol

TL;DR

This study reveals that dielectric relaxation in glycerol exhibits non-local behavior at low temperatures, with relaxation times depending on system size, challenging the traditional view of relaxation as an intrinsic local property.

Contribution

The paper demonstrates the existence of non-local dielectric relaxation in glycerol at low temperatures and links it to liquid elasticity length, supported by experimental data and theoretical analysis.

Findings

Relaxation time increases with system size at low temperatures.

Non-local dielectric relaxation becomes significant below a certain temperature.

Good agreement between experimental results and elastic wave interaction theory.

Abstract

Since its introduction, liquid viscosity and relaxation time $\tau$ have been considered to be an intrinsic property of the system that is essentially local in nature and therefore independent of system size. We perform dielectric relaxation experiments in glycerol, and find that this is the case at high temperature only. At low temperature, $\tau$ increases with system size and becomes non-local. We discuss the origin of this effect in a picture based on liquid elasticity length, the length over which local relaxation events in a liquid interact via induced elastic waves, and find good agreement between experiment and theory.