Adsorption of C₆₀ on Ta(110): Photoemission and C K-edge studies

Photoelectron and near-edge spectroscopies are used to characterize a C₆₀ film on a Ta(110) surface. Like similar studies of C₆₀ on a variety of metal surfaces, the valence band, C 1s core level, and photoelectron-derived work-function measurements show that C₆₀ molecular states are aligned with the Fermi level and the charge is transferred from the metal to the fullerene. The photoelectron and near-edge spectra of the C₆₀ peaks closest to the Fermi level show significant changes in intensity identifying those π-like states as interacting with the substrate. A careful examination of the C 1s and Ta 4f core levels suggests that some fraction of the fullerene overlayer decomposes on the clean metal surface leading to or resulting in, a thin layer of carbon between the assembled film and the metal substrate.