Concentrated suspensions of Brownian beads in water: dynamic heterogeneities trough a simple experimental technique

Abstract

Concentrated suspensions of Brownian hard-spheres in water are an epitome for understanding the glassy dynamics of both soft materials and supercooled molecular liquids. From an experimental point of view, such systems are especially suited to perform particle tracking easily, and, therefore, are a benchmark for novel optical techniques, applicable when primary particles cannot be resolved. Differential Variance Analysis (DVA) is one such novel technique that simplifies significantly the characterization of structural relaxation processes of soft glassy materials, since it is directly applicable to digital image sequences of the sample. DVA succeeds in monitoring not only the average dynamics, but also its spatio-temporal fluctuations, known as dynamic heterogeneities. In this work, we study the dynamics of dense suspensions of Brownian beads in water, imaged through digital video-microscopy, by using both DVA and single-particle tracking. We focus on two commonly used signatures of dynamic heterogeneities: the dynamic susceptibility, ${\chi }_4$, and the non-Gaussian parameter, ${\alpha }_2$. By direct comparison of these two quantities, we are able to highlight similarities and differences. We do confirm that ${\chi }_4$ and ${\alpha }_2$ provide qualitatively similar information, but we find quantitative discrepancies in the scalings of characteristic time and length scale on approaching the glass transition.

The original publication is available at http://www.scichina.com and http://www.springerlink.com http://engine.scichina.com/publisher/scp/journal/SCPMA/doi/10.1007/s11433-019-9401-x?slug=abstract

References in corpus (12)

• Supercooled Liquids for Pedestrians
• The role of local structure in dynamical arrest
• Differential Dynamic Microscopy: Probing wave vector dependent dynamics with a microscope
• Dynamic heterogeneity in amorphous materials
• Direct measurements of growing amorphous order and non-monotonic dynamic correlations in a colloidal glass-former
• Resolving long-range spatial correlations in jammed colloidal systems using photon correlation imaging
• Unexpected drop of dynamical heterogeneities in colloidal suspensions approaching the jamming transition
• Relaxation in yield stress systems through elastically interacting activated events
• Dichotomic Aging Behaviour in a Colloidal Glass
• Jamming and growth of dynamical heterogeneities versus depth for granular heap flow
• Structural and microscopic relaxations in a colloidal glass
• Connecting short and long time dynamics in hard-sphere-like colloidal glasses

Cited by in corpus (1)

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