α-Scale decoupling of the mechanical relaxation and diverging shear wave propagation length scale in triphenylphosphite

We have performed depolarized impulsive stimulated scattering experiments to observe shear acoustic phonons in supercooled triphenylphosphite (TPP) from ∼10–500 MHz. These measurements, in tandem with previously performed longitudinal and shear measurements, permit further analyses of the relaxation...

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Bibliographic Details
Main Authors: Torchinsky, Darius H., Johnson, Jeremiah A., Nelson, Keith Adam
Other Authors: Massachusetts Institute of Technology. Department of Chemistry
Format: Article
Language:en_US
Published: American Institute of Physics (AIP) 2013
Online Access:http://hdl.handle.net/1721.1/82543
https://orcid.org/0000-0001-7804-5418
https://orcid.org/0000-0001-9157-6491
Description
Summary:We have performed depolarized impulsive stimulated scattering experiments to observe shear acoustic phonons in supercooled triphenylphosphite (TPP) from ∼10–500 MHz. These measurements, in tandem with previously performed longitudinal and shear measurements, permit further analyses of the relaxation dynamics of TPP within the framework of the mode coupling theory. Our results provide evidence of α coupling between the shear and longitudinal degrees of freedom up to a decoupling temperature T [subscript c] = 231 K. A lower bound length scale of shear wave propagation in liquids verified the exponent predicted by theory in the vicinity of the decoupling temperature.