Electronic states of a C70 monolayer on the surface of Ag(111)

We have investigated the electronic states of a C70?monolayer on the surface of Ag(111) (1?ML C70/Ag(111)) using synchrotron radiation photoelectron spectroscopy and soft x-ray absorption spectroscopy techniques. The experimental data exhibit metallic properties and at least 2.6?e? charge transfer per C70 molecule. The screening effect of Ag(111) on the electronic structure of C70 is remarkable; it greatly reduces or even eliminates the on-site Hubbard energy. The work functions of the C70 multilayer and monolayer are determined as 4.53?eV and 4.52?eV respectively. The energy levels of C70 align with the Fermi level of the Ag(111) substrate, and the shift of the vacuum level caused by C70 adsorption is negligible. Potassium doping indicates that 1?ML C70/Ag(111) can still accommodate about nine electrons and that the sample remains metallic at any doping level.