title: Isotropic rotation vs. shear relaxation in supercooled liquids with globular cage molecules.
abstract: The temperature dependence of the rotational dynamics of P4Se3 molecules in the glass-forming molecular liquid P5Se3 is studied using two-dimensional (31)P 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.
authors.affiliation: Division of Materials Science, University of California at Davis, Davis, California 95616, USA.
authors.forename: Derrick C
authors.initials: DC
authors.lastname: Kaseman
authors.affiliation: Science and Technology Division, Corning Incorporated, Corning, New York 14831, USA.
authors.forename: Ozgur
authors.initials: O
authors.lastname: Gulbiten
authors.affiliation: Science and Technology Division, Corning Incorporated, Corning, New York 14831, USA.
authors.forename: Bruce G
authors.initials: BG
authors.lastname: Aitken
authors.affiliation: Division of Materials Science, University of California at Davis, Davis, California 95616, USA.
authors.forename: Sabyasachi
authors.initials: S
authors.lastname: Sen