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Abstract: We performed high-resolution photoemission experiments at different photon energies to investigate the valence band structure of 1ML of 1,4,5,8-naphthalene tetracarboxylic dianhydride (NTCDA) on Ag(111). Besides the known occupied molecular orbitals HOMO and HOMO−1 we observe a new state close to the Fermi level, which results from the interaction between NTCDA and the substrate, partially filling the lowest unoccupied orbital of the free molecule (LUMO) in the monolayer system. By tuning the photon energy through the carbon K-edge, a resonance like change of the spectral intensity at the HOMO and HOMO−1 energies is clearly revealed, which we use for an assignment of the individual spectral features to a predominant localization either at the naphthalene core or the anhydride group. [Copyright &y& Elsevier]

Abstract: One monolayer of Ag deposited on Cu(111) shows two kinds of characteristic reconstruction, depending on the conditions of the preparation: the incommensurate moiré structure appears for one monolayer prepared at 200K whereas a monolayer deposited at room temperature (or higher) exhibits a quasi-commensurate triangular structure. By high-resolution ARUPS measurements on the triangular structure we find an opening of a gap in the Shockley state band, which is a signature of the super-lattice. On the other hand, no gap opening is observed on the moiré structure. In addition, we show that the Shockley state plays an important role in the adsorption process of rare gas atoms on these surfaces. ARUPS experiments on adsorbed Xe on 0.6ML Ag/Cu(111) show clearly that the Xe atoms favor the adsorption on the Ag islands, before the Cu terraces will be covered at higher Xe exposure. [Copyright &y& Elsevier]