title: Nanostructuring of Au(111) during the Adsorption of an Aromatic Isocyanide from Solution.
abstract: We present a combined vibrational and morphological characterization of the self-assembly of 1,4-phenylene-diisocyanide (PDI) on Au(111) from methanol solution. Vibrational sum frequency generation (vSFG) and scanning tunneling microscopy (STM) have been applied to determine the adsorption geometry of the PDI-Au adatom complexes as well as the morphological transformations of the Au(111) substrate upon SAM formation from solutions with PDI concentrations in the μM to mM range. At low concentration/coverage, PDI adsorbs in flat adsorption geometry, with both isocyanide groups attached to Au adatoms on the Au(111) surface. Transformation to a standing-up phase is observed with increasing concentration/coverage. In contrast to findings for PDI adsorbed in ultrahigh vacuum, PDI does not form a long-range-ordered monolayer phase when adsorbed from solution. In addition, the Au(111) surface is subjected to structural modifications. Au vacancy islands and ad-islands, which are typical substrate defects formed during the self-assembly of aromatic thiols on Au(111), are also created during PDI adsorption from solution. At low PDI concentration, the Au vacancy islands and ad-islands are found at specific sites mediated by the herringbone reconstruction of the Au(111) surface, giving rise to long-range-ordered structures. These structures do not form during UHV adsorption of PDI on Au(111) nor has a similar ordering effect been observed for any related thiol-SAM system investigated so far.
authors.affiliation: Institute of Physics, University of Graz , Universitätsplatz 5, A-8010 Graz, Austria.|Department of Chemical Physics, Fritz-Haber-Institut der Max-Planck-Gesellschaft , Faradayweg 4-6, D-14195 Berlin, Germany.
authors.forename: Ahmed
authors.initials: A
authors.lastname: Ghalgaoui
authors.affiliation: Institute of Physics, University of Graz , Universitätsplatz 5, A-8010 Graz, Austria.
authors.forename: Nassar
authors.initials: N
authors.lastname: Doudin
authors.affiliation: Institute of Physics, University of Graz , Universitätsplatz 5, A-8010 Graz, Austria.|Department of Chemical Physics, Fritz-Haber-Institut der Max-Planck-Gesellschaft , Faradayweg 4-6, D-14195 Berlin, Germany.
authors.forename: Martin
authors.identifier: 0000-0001-9089-9061
authors.initials: M
authors.lastname: Sterrer