Determination of charge states of ${\mathrm{C}}_{60}$ adsorbed on metal surfaces

The charge transfer per molecule in a ${\mathrm{C}}_{60}$ monolayer on Au(110), on K/Au(110)c(2×2), and on a K multilayer has been determined by studying the electronic excitations from the valence bands and from the C 1s core level and the vibrational modes of the systems by electron energy loss spectroscopy. The electrons transferred are 1±1, 3±1, and 6±1, respectively. These results indicate strong chemical bonding of ${\mathrm{C}}_{60}$ on such metal surfaces.