Photoemission study of chemisorption of C-60 on InP(100)

The growth mode and electronic structure of C-60 molecules adsorbed on InP(100) were studied by x-ray photoemission spectroscopy and ultraviolet photoemission spectroscopy as a function of coverage and annealing temperature. The C 1s, P 2p, In 4d core levels and the valence band photoemission spectra point to the presence of a localized covalent bond between the C-60 molecules and the substrate. No filling of the lowest unoccupied molecular orbit derived bands was observed. The absence of any change in the surface components of the In 4d core level upon C-60 adsorption indicates that the chemisorption bond exists between the fullerene molecules and P atoms rather than between C-60 molecules and In atoms, This assertion is supported by the simultaneous desorption of both C-60 and P upon annealing to 640 K and above.