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Title: Coherent neutron scattering and collective dynamics on mesoscale

Abstract

By combining, and modestly extending, a variety of theoretical concepts for the dynamics of liquidsin the supercooled regime, we formulate a simple analytic model for the temperature and wavevectordependent collective density fluctuation relaxation time that is measurable using coherent dynamicneutron scattering. Comparison with experiments on the ionic glass-forming liquid Ca–K–NO3 in thelightly supercooled regime suggests the model captures the key physics in both the local cage andmesoscopic regimes, including the unusual wavevector dependence of the collective structural relaxationtime. The model is consistent with the idea that the decoupling between diffusion and viscosityis reflected in a different temperature dependence of the collective relaxation time at intermediatewavevectors and near the main (cage) peak of the static structure factor. More generally, our analysisprovides support for the ideas that decoupling information and growing dynamic length scales can beat least qualitatively deduced by analyzing the collective relaxation time as a function of temperatureand wavevector, and that there is a strong link between dynamic heterogeneity phenomena at thesingle and many particle level. Though very simple, the model can be applied to other systems, suchas molecular liquids.

Authors:
 [1];  [1]; ORCiD logo [1]
  1. ORNL
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1088153
DOE Contract Number:  
AC05-00OR22725
Resource Type:
Journal Article
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 138; Journal Issue: 138; Journal ID: ISSN 0021-9606
Country of Publication:
United States
Language:
English

Citation Formats

Novikov, Vladimir, Schweizer, Kenneth S., and Sokolov, Alexei P. Coherent neutron scattering and collective dynamics on mesoscale. United States: N. p., 2013. Web. doi:10.1063/1.4802771.
Novikov, Vladimir, Schweizer, Kenneth S., & Sokolov, Alexei P. Coherent neutron scattering and collective dynamics on mesoscale. United States. doi:10.1063/1.4802771.
Novikov, Vladimir, Schweizer, Kenneth S., and Sokolov, Alexei P. Mon . "Coherent neutron scattering and collective dynamics on mesoscale". United States. doi:10.1063/1.4802771.
@article{osti_1088153,
title = {Coherent neutron scattering and collective dynamics on mesoscale},
author = {Novikov, Vladimir and Schweizer, Kenneth S. and Sokolov, Alexei P.},
abstractNote = {By combining, and modestly extending, a variety of theoretical concepts for the dynamics of liquidsin the supercooled regime, we formulate a simple analytic model for the temperature and wavevectordependent collective density fluctuation relaxation time that is measurable using coherent dynamicneutron scattering. Comparison with experiments on the ionic glass-forming liquid Ca–K–NO3 in thelightly supercooled regime suggests the model captures the key physics in both the local cage andmesoscopic regimes, including the unusual wavevector dependence of the collective structural relaxationtime. The model is consistent with the idea that the decoupling between diffusion and viscosityis reflected in a different temperature dependence of the collective relaxation time at intermediatewavevectors and near the main (cage) peak of the static structure factor. More generally, our analysisprovides support for the ideas that decoupling information and growing dynamic length scales can beat least qualitatively deduced by analyzing the collective relaxation time as a function of temperatureand wavevector, and that there is a strong link between dynamic heterogeneity phenomena at thesingle and many particle level. Though very simple, the model can be applied to other systems, suchas molecular liquids.},
doi = {10.1063/1.4802771},
journal = {Journal of Chemical Physics},
issn = {0021-9606},
number = 138,
volume = 138,
place = {United States},
year = {2013},
month = {4}
}

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