Orientational behavior of C70 molecules in chlorobenzene

The orientational behavior of C70 singlet excited molecules in a chlorobenzene solution has been measured at room temperature by the picosecond transient grating technique. A two-stage decay signal was observed: a fast part (τ = 12 ± 5 ps) which is comparable with the corresponding signal of C60 in chlorobenzene (τ = 8 ± 2 ps), and a slow part (τ = 30 ± 5 ps). The data obtained are analyzed in terms of the rotation of C70 molecules. The influence of the dielectric friction on the C70 rotation is reported.