Dynamics of Rod like Particles in Supercooled Liquids -- Probing Dynamic Heterogeneity and Amorphous Order

TL;DR

This paper introduces a new method using rod-like particles to measure both dynamic and static correlations in supercooled liquids, aiding understanding of glassy dynamics and amorphous order.

Contribution

The authors propose a novel experimental approach employing rod-like probes to simultaneously extract dynamic and static correlations in glass-forming systems.

Findings

Distribution of rotational decorrelation times is log-normal.

Method enables measurement of correlation lengths in experiments.

Applicable to molecular liquids and biological systems.

Abstract

Probing dynamic and static correlation in glass-forming supercooled liquids has been a challenge for decades in spite of extensive research. Dynamic correlation which manifests itself as Dynamic Heterogeneity is ubiquitous in a vast variety of systems starting from molecular glass-forming liquids, dense colloidal systems to collections of cells. On the other hand, the mere concept of static correlation in these dense disordered systems remain somewhat elusive and its existence is still actively debated. We propose a novel method to extract both dynamic and static correlations using rod-like particles as probe. This method can be implemented in molecular glass-forming liquids in experiments as well as in other soft matter systems including biologically relevant systems. We also rationalize the observed log-normal like distribution of rotational decorrelation time of elongated probe molecules in reported experimental studies along with a proposal of a novel methodology to extract dynamic and static correlation lengths in experiments.