C-60 ON AL(111) - COVALENT BONDING AND SURFACE RECONSTRUCTION

We present photoemission and C 1s photoabsorption data for an annealed monolayer C-60/Al(111), which show that a strong covalent bond is for med between the C-60 molecules and the substrate. Low-energy electron- diffraction and scanning tunneling microscopy data reveal a highly sym metric overlayer structure commensurate with the substrate. Al 2p phot oelectron spectra show that the chemical environment at the surface is greatly modified compared to clean Al(111), and indicate that a signi ficant fraction of the surface atoms have moved, consistent with a pic ture of covalent bonding to the overlayer. The strength of the interac tion is such that the fullerenes are distorted more than on other meta l surfaces or in compounds with alkali metals.