The EEL spectrum of the triplet exciton of C-60 and the theoretical analysis of its vibronic structure

The electron energy loss (EEL) spectrum of the tripler exciton of the (111) surface of solid C-60 has been recorded at 105 K. Its rich vibronic structure is suggestive of a high degree of molecular distortion that occurs upon excitation, The static Jahn-Teller distortion of the isolated molecule, along the adiabatic potential energy surface of T-1, is determined by quantum-chemical calculations and the relaxed molecular structure is found to belong to the D-5d point group symmetry, The vibrational force field is evaluated at the distorted structure and used to simulate the EEL intensities of phonon-assisted transitions in the strong coupling regime.