Decoupling of rotational and translational diffusion in supercooled colloidal fluids

We use confocal microscopy to directly observe 3D translational and rotational diffusion of tetrahedral clusters, which serve as tracers in colloidal supercooled fluids. We find that as the colloidal glass transition is approached, translational and rotational diffusion decouple from each other: Rot...

Full description

Saved in:
Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2012-10, Vol.109 (44), p.17891-17896
Main Authors: Edmond, Kazem V, Elsesser, Mark T, Hunter, Gary L, Pine, David J, Weeks, Eric R
Format: Article
Language:English
Subjects:
Chemical suspensions
Colloids
confocal microscopy
Diffusion coefficient
Fluids
Glass
glass transition
Kinetics
Liquids
Material concentration
Normal distribution
Phase transitions
Physical Sciences
Rotation
Simulation
tracer techniques
Trajectories
translation (genetics)
Viscosity
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:We use confocal microscopy to directly observe 3D translational and rotational diffusion of tetrahedral clusters, which serve as tracers in colloidal supercooled fluids. We find that as the colloidal glass transition is approached, translational and rotational diffusion decouple from each other: Rotational diffusion remains inversely proportional to the growing viscosity whereas translational diffusion does not, decreasing by a much lesser extent. We quantify the rotational motion with two distinct methods, finding agreement between these methods, in contrast with recent simulation results. The decoupling coincides with the emergence of non-Gaussian displacement distributions for translation whereas rotational displacement distributions remain Gaussian. Ultimately, our work demonstrates that as the glass transition is approached, the sample can no longer be approximated as a continuum fluid when considering diffusion.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.1203328109