Size dependence of tracer diffusion in supercooled liquids

We have determined by forced Rayleigh scattering the diffusion coefficients D of several photochromic tracers with van der Waals radii between 0.38 and 8 nm (the largest ones being photolabeled polystyrene micronetworks) in 10 glass-forming liquids at temperatures between the glass temperature T-g and similar to 1.2T(g) The results were analyzed in terms of power law plots, D(T) proportional to T/eta(T)(xi), where eta is the solvent shear viscosity, and temperature shifts, D(T) proportional to T/eta(T + Delta T). The shift Delta T was related with the width of the rotational correlation time distribution via the time-temperature superposition principle.