Isotropic rotation vs. shear relaxation in supercooled liquids with globular cage molecules

The temperature dependence of the rotational dynamics of P4Se3 molecules in the glass-forming molecular liquid P5Se3 is studied using two-dimensional 31P nuclear magnetic resonance spectroscopy. Unlike typical molecular glass-forming liquids, the constituent molecules in the P5Se3 liquid perform rap...

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Veröffentlicht in:The Journal of chemical physics 2016-05, Vol.144 (17), p.174501-174501
Hauptverfasser: Kaseman, Derrick C., Gulbiten, Ozgur, Aitken, Bruce G., Sen, Sabyasachi
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Sprache:eng
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Zusammenfassung:The temperature dependence of the rotational dynamics of P4Se3 molecules in the glass-forming molecular liquid P5Se3 is studied using two-dimensional 31P nuclear magnetic resonance spectroscopy. Unlike typical molecular glass-forming liquids, the constituent molecules in the P5Se3 liquid perform rapid isotropic rotation without significant translational diffusion in the supercooled regime and this rotational process shows a decoupling in time scale from shear relaxation by nearly six orders of magnitude at the glass transition. This dynamical behavior of liquid-like rotation and localized translation appears to be universal to glass-forming liquids with high-symmetry globular molecules that are characterized by an underlying thermodynamically stable plastic crystal phase.
ISSN:0021-9606
1089-7690
DOI:10.1063/1.4947479