Dynamics of fullerene C70 in the lowest excited triplet state at low temperatures

The dynamic behavior of C[sub 70] in the lowest excited triplet state is investigated by the time-resolved EPR (TREPR) method in methylcyclohexane at low temperatures. From the line width of the TREPR spectrum, the distributions of the shortest and middle radii of the distorted rugby ball shape are revealed to be inhomogeneously broadened although the longest radius is relatively constant. The observing time dependence of the spectrum after the laser excitation is examined on the basis of the model involving pseudorotation and molecular rotation. The time dependence calculated based on the pseudorotation around the longest axis fits the observed one well. The activation energy of the dynamic deformation is determined. 16 refs., 4 figs.