Metallization of the C-60/Rh(100) interface revealed by valence photoelectron spectroscopy and density functional theory calculations

Wade, Abdou-Ciss
Lizzit, Silvano
Petaccia, Luca
Goldoni, Andrea
Diop, Djibril
Toffoli, Hande
Fabris, Stefano
Baroni, Stefano
The electronic structure of single and multiple layers of C-60 molecules deposited on a Rh(100) surface is investigated by means of valence photoemission spectroscopy and density functional theory calculations. The binding of the fullerene monolayer to the metal surface yields the appearance of a new state in the valence band spectrum crossing the Fermi level. Insight into the metallization of the metal/fullerene interface is provided by the calculated electronic structure that allows us to correlate the measured interface state with a strong hybridization between the Rh metal states and the highest and lowest molecular orbitals. This results in a net charge transfer of approximate to 0.5e-0.6e from the metal to the p states of the interfacial C atoms. The charge transfer is shown to be very short range, involving only the C atoms bound to the metal. The electronic structure of the second C-60 layer is already insulating and resembles the one measured for C-60 multilayers supported by the same substrate or calculated for fullerenes isolated in vacuum. The discussion of the results in the context of other C-60/metal systems highlights the distinctive electronic properties of the molecule/metal interface determined by the Rh support. (c) 2010 American Institute of Physics. [doi: 10.1063/1.3432778]