Dynamic crossover in supercooled liquids induced by high pressure

The physics underlying the dynamics of molecules near their glass temperature, Tg, comprises one of the major unsolved problems in condensed matter. Of particular interest are the striking changes in relaxation properties observed at temperatures ∼1.2 times higher than Tg. Herein, we describe experi...

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Bibliographic Details
Published in:The Journal of chemical physics 2003-04, Vol.118 (13), p.5701-5703
Main Authors: Casalini, Riccardo, Paluch, Marian, Roland, C. Michael
Format: Article
Language:English
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Summary:The physics underlying the dynamics of molecules near their glass temperature, Tg, comprises one of the major unsolved problems in condensed matter. Of particular interest are the striking changes in relaxation properties observed at temperatures ∼1.2 times higher than Tg. Herein, we describe experiments in which these changes in dynamics are induced by pressure variations. For several supercooled liquids, the relaxation time associated with the change in dynamics is found to be invariant to both temperature and pressure. That is, the time scale of the molecular motions determines the onset of strong intermolecular cooperativity and the accompanying dynamical changes. While thermodynamic variables such as temperature and pressure influence the crossover in dynamics, the governing variable is the time scale.
ISSN:0021-9606
1089-7690
DOI:10.1063/1.1564046