Orientation and electronic structure of pyrazine adsorbed on Ag(111)

Abstract

Near-edge X-ray absorption fine structure (NEXAFS) and angle-resolved photoemission spectra from ordered pyrazine layers with thicknesses ranging from submonolayer to multilayer coverages on Ag(111) have been measured using synchrotron radiation. LEED reveals a (2×2) ordered adsorbate structure. The polarization dependence of the NEXAFS shows on orientation of the pyrazine molecular plane parallel to the metal surface. The angular dependence of the photoemission corroborates this result. Furthermore, a complete mapping of the valence bands and an improved symmetry assignment of the bands emerges. Substrate-induced changes in the pyrazine molecular orbital (MO) structure for the first layer can be identified in a similar way to the pyridine/Ag (111) system