The surface triplet exciton of C60(111)

The electron energy loss spectrum of the triplet exciton of [111] oriented C60 films has been measured as a function of temperature, film thickness and primary electron energy. The triplet exciton of the [111] surface is found at 1.549 eV and that of the bulk at 1.64 eV. The vibrational structure of the spectrum is in agreement with the T2g symmetry of the electronic wavefunction and with the molecular distortion of the excited state predicted by calculations.