Self-diffusion of tris-naphthylbenzene near the glass transition temperature.
We present a direct measurement of self-diffusion of a single-component glass-forming liquid at the glass transition temperature. Forward recoil spectrometry is used to measure the concentration profiles of deuterio and protio 1,3-bis-(1-naphthyl)-5-(2-naphthyl)benzene (TNB) following annealing-induced diffusion in a vapor-deposited bilayer. These experiments extend the range of measured diffusion coefficients in TNB by 6 orders of magnitude. The results indicate a decoupling of translational diffusion coefficients from viscosity or rotation. At T(g), D(T) is 400 times larger than expected from the Stokes-Einstein equation.
Swallen
Stephen F
SF
Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
Bonvallet
Paul A
PA
McMahon
Robert J
RJ
Ediger
M D
MD