Phys Chem Chem Phys. 2016 Feb 07;18(5):3975-81. doi: 10.1039/c5cp05143f. Epub 2016 Jan 15.

A robust comparison of dynamical scenarios in a glass-forming liquid.

Physical chemistry chemical physics : PCCP

Alessandro Vispa, Sebastian Busch, Josep Lluis Tamarit, Tobias Unruh, Felix Fernandez-Alonso, Luis Carlos Pardo

PMID: 26771030 DOI: 10.1039/c5cp05143f

Abstract

We use Bayesian inference methods to provide fresh insights into the sub-nanosecond dynamics of glycerol, a prototypical glass-forming liquid. To this end, quasielastic neutron scattering data as a function of temperature have been analyzed using a minimal set of underlying physical assumptions. On the basis of this analysis, we establish the unambiguous presence of three distinct dynamical processes in glycerol, namely, translational diffusion of the molecular centre of mass and two additional localized and temperature-independent modes. The neutron data also provide access to the characteristic length scales associated with these motions in a model-independent manner, from which we conclude that the faster (slower) localized motions probe longer (shorter) length scales. Careful Bayesian analysis of the entire scattering law favors a heterogeneous scenario for the microscopic dynamics of glycerol, where molecules undergo either the faster and longer or the slower and shorter localized motions.

Publication Types

• Journal Article
• Research Support, Non-U.S. Gov't