ANISOTROPY TIME-DEPENDENCE OF PHOTOEXCITED C-60 AND C-70 IN TRANSIENTGRATING EXPERIMENTS - SOLVENT EFFECT

Anisotropy time dependence of photoexcited C-60 and C-70 has been meas ured by picosecond transient grating techniques at room temperature in various solvents. The monoexponential anisotropy decay was observed f or the C-60 molecule and biexponential anisotropy decay was observed f or the C-70 molecule. Both for the C-60 and for the C-70 molecules ani sotropy time decay is very fast. The data obtained were analyzed in te rms of the rotational reorientation of fullerene molecules in solvents . Hynes-Kapral-Weinberg theory reasonably explains the observed reorie ntation times of fullerenes molecules. The dielectric friction effect on the C-70 rotational reorientation on the short axis is reported.