  We have studied the low-energy electronic excitations of solid picene at 20 K
using momentum dependent electron energy-loss spectroscopy. Our results
demonstrate the presence of five excitonic features below the transport energy
gap of picene, which all are characterized by a negligible dispersion. One of
these excitons has not been observed in the optical absorption spectrum of
picene molecules in solution and thus is assigned to a (solid-state induced)
charge transfer exciton. This conclusion is supported by the momentum dependent
intensity variation of this exciton which clearly signals a significant dipole
forbidden contribution, in contrast to the other low energy excitations.

Materials Science;Superconductivity