We have determined by forced Rayleigh scattering the diffusion coeffic
ients D of several photochromic tracers with van der Waals radii betwe
en 0.38 and 8 nm (the largest ones being photolabeled polystyrene micr
onetworks) in 10 glass-forming liquids at temperatures between the gla
ss 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 et
a is the solvent shear viscosity, and temperature shifts, D(T) proport
ional to T/eta(T + Delta T). The shift Delta T was related with the wi
dth of the rotational correlation time distribution via the time-tempe
rature superposition principle.