Experimental verification of democratic particle motions by direct imaging of glassy colloidal systems

TL;DR

This study uses confocal microscopy to directly observe and validate the role of rapid sporadic particle motions in the structural relaxation of glassy colloidal systems, confirming key theoretical predictions.

Contribution

It provides experimental evidence for the existence of rapid sporadic events and cluster mobility in glassy colloids, supporting longstanding theoretical models.

Findings

Confirmation of rapid sporadic events driving relaxation

Observation of compact clusters of mobility

Agreement with Adam-Gibbs and Goldstein theories

Abstract

We analyze data from confocal microscopy experiments of a colloidal suspension to validate predictions of rapid sporadic events responsible for structural relaxation in a glassy sample. The trajectories of several thousand colloidal particles are analyzed, confirming the existence of rapid sporadic events responsible for the structural relaxation of significant regions of the sample, and complementing prior observations of dynamical heterogeneity. The emergence of relatively compact clusters of mobility allows the dynamics to transition between the large periods of local confinement within its potential energy surface, in good agreement with the picture envisioned long ago by Adam and Gibbs and Goldstein.