MEASUREMENT OF THE SELF-DIFFUSION COEFFICIENT OF C-60 IN BENZENE-D(6) USING C-13 PULSED-GRADIENT SPIN-ECHO

We report first measurements of the self-diffusion coefficient (D) of C60 (30% C-13 labeled) in benzene-d6 with the pulsed-gradient spin-echo method. The observed D value, (8.3 +/- 0.7) x 10(-10) m2 s-1 at 298 K, is slightly higher than that calculated from the Stokes-Einstein equation with stick boundary conditions using the van der Waals radius of C60, 0.51 nm. (A fit to our data requires replacement of the radius by 0.41 +/- 0.04 nm.) When the empirical equation proposed by Evans et al. is applied to our system, on the other hand, we obtain, the self-diffusion coefficient of 8.0 x 10(-10) M2 s-1, Which is in good agreement with the observed value.