Resolving long-range spatial correlations in jammed colloidal systems using photon correlation imaging

TL;DR

This paper introduces photon correlation imaging, a new dynamic light scattering technique, to study long-range spatial correlations in jammed colloidal systems, revealing the significant role of mechanical properties in their dynamics.

Contribution

The paper presents a novel imaging method that resolves spatial and temporal dynamics in soft matter, demonstrating long-range correlations in jammed systems.

Findings

Dynamical correlations extend up to system size in gel networks.

Rearrangements in foam are localized but influence large areas.

Long-range correlations are linked to mechanical properties of the systems.

Abstract

We introduce a new dynamic light scattering method, termed photon correlation imaging, which enables us to resolve the dynamics of soft matter in space and time. We demonstrate photon correlation imaging by investigating the slow dynamics of a quasi two-dimensional coarsening foam made of highly packed, deformable bubbles and a rigid gel network formed by dilute, attractive colloidal particles. We find the dynamics of both systems to be determined by intermittent rearrangement events. For the foam, the rearrangements extend over a few bubbles, but a small dynamical correlation is observed up to macroscopic length scales. For the gel, dynamical correlations extend up to the system size. These results indicate that dynamical correlations can be extremely long-ranged in jammed systems and point to the key role of mechanical properties in determining their nature.