  The electronic structure of the unoccupied and occupied states of potassium
(K)-doped and undoped picene crystalline films has been investigated by using
the element-selective and bulk-sensitive photon-detection methods of X-ray
absorption and emission spectroscopies. We observed the formation of the
doping-induced unoccupied and occupied electronic states in K-doped picene. By
applying the inner-shell resonant-excitation experiments, we observed the
evidence for the orbital hybridization between K and picene near the Fermi
energy. Furthermore, the resonant X-ray emission experiment suggests the
presence of the Raman-active vibronic interaction in K-doped picene. These
experimental evidences play a crucial role in the superconductivity of K-doped
picene.
