Probing the mobility of supercooled liquid 3-methylpentane at temperatures near the glass transition using rare gas permeation

TY - JOUR

T1 - Probing the mobility of supercooled liquid 3-methylpentane at temperatures near the glass transition using rare gas permeation

AU - Matthiesen, Jesper

AU - Smith, R. Scott

AU - Kay, Bruce D.

PY - 2012/8/14

Y1 - 2012/8/14

N2 - We study the diffusivity of three-methylpentane (3MP) using the permeation of inert gases (Ar, Kr, Xe) through the supercooled liquid created when initially amorphous overlayers are heated above T g. We find that the permeation rates for all of the gases have nonArrhenius temperature dependences that are well described by the Vogel-Fulcher-Tamman equation. Comparison with the literature viscosity shows that the Stokes-Einstein equation breaks down at temperatures approaching T g. The fractional Stokes-Einstein equation, D (Tη) n, does fit the permeation data, albeit with different values of n for each gas. There is qualitative agreement with the StokesEinstein equation in that the permeation rate decreases with increasing radius of the rare gas probe, but the small differences in radii significantly underestimate the observed differences in the permeation rates. Instead the permeation rates are better correlated with the rare gas-3MP interaction energy than with the atomic radius.

AB - We study the diffusivity of three-methylpentane (3MP) using the permeation of inert gases (Ar, Kr, Xe) through the supercooled liquid created when initially amorphous overlayers are heated above T g. We find that the permeation rates for all of the gases have nonArrhenius temperature dependences that are well described by the Vogel-Fulcher-Tamman equation. Comparison with the literature viscosity shows that the Stokes-Einstein equation breaks down at temperatures approaching T g. The fractional Stokes-Einstein equation, D (Tη) n, does fit the permeation data, albeit with different values of n for each gas. There is qualitative agreement with the StokesEinstein equation in that the permeation rate decreases with increasing radius of the rare gas probe, but the small differences in radii significantly underestimate the observed differences in the permeation rates. Instead the permeation rates are better correlated with the rare gas-3MP interaction energy than with the atomic radius.

U2 - 10.1063/1.4743902

DO - 10.1063/1.4743902

M3 - Journal article

C2 - 22897295

SN - 0021-9606

VL - 137

JO - The Journal of Chemical Physics

JF - The Journal of Chemical Physics

IS - 6

M1 - 064509

ER -