ADSORPTION OF C60 ON Li-COVERED Ni(110) SURFACES

Abstract

In this paper the adsorption of C60 on Li-covered Ni(110) surfaces is investigated by means of Auger electron spectroscopy, low-energy electron diffraction and work function measurements, in ultrahigh vacuum. Deposition of C60 on the 1 × 2 Li-induced Ni(110) surface at 650 K causes the formation of islands with a 4 × 2 structure, where the C60 molecules adsorb along neighboring troughs of the substrate. At higher C60 coverages, the Li-induced 1 × 2 reconstruction of the Ni(110) surface is lifted and a 9 × 3 structure is formed, which finally ends in a semihexagonal structure, as in the case of C60 adsorption on clean Ni(110) surfaces. AES and LEED measurements suggest that charge is transferred from Li to the C60 molecules, which in a rough approximation was estimated to be around one electron per C60 molecule. The above estimated charge transfer to the C60 molecules is substantially smaller than that we have calculated when Li is adsorbed on C60-covered Ni(110) surfaces. Apparently, the order of Li and C60 deposition is very important for the charge transfer and the deposition of Li on C60-covered surfaces provides a substantially greater amount of charge to the C60 molecules.