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

• Main Authors: Torchinsky, Darius H. (Contributor), Johnson, Jeremiah A. (Contributor), Nelson, Keith Adam (Contributor)
• Other Authors: Massachusetts Institute of Technology. Department of Chemistry (Contributor), Massachusetts Institute of Technology. Department of Physics (Contributor)
• Format: Article
• Language: English
• Published: American Institute of Physics (AIP), 2013-11-22T15:31:30Z.
• Subjects: Article
• Online Access: Get fulltext

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.
National Science Foundation (U.S.) (Grant CHE-0616939)
National Science Foundation (U.S.) (Grant IMR-0414895)