Structure of C60 Adsorbed on Pt(111): Detailed LEED and DFT Analysis

Buckyballs (C60) adsorb on Pt(111) in ordered structures with periodicities (Ö13xÖ13)R13.9º and (2Ö3x2Ö3)R30º. LEED intensities were measured for these structures with a LEEM instrument. Since LEED intensities at room temperature are very weak above about 150 eV, the LEED data were recorded for the two structures at 100K in the energy range up to 700 eV. Preliminary results of our tensor-LEED analysis support our theoretical predictions from DFT calculations that favor a single-missing-atom reconstruction of the Pt(111) substrate, i.e. a model in which the center of each buckyball rests over the site of a single missing Pt atom of the outermost Pt layer. This result can be compared with the same conclusion reached recently for buckyballs adsorbed in a (2Ö3x2Ö3)R30º pattern on Ag(111) [H.I. Li et al, PRL 103, 056101 (2009)], but with a different conclusion of a 7-missing-atom reconstruction for buckyballs adsorbed in a (4x4) pattern on Cu(111) [W.W. Pai et al, PRL 104, 036103 (2010)].