Sorbonne Universités, UPMC Univ Paris 06, CNRS-UMR 7588, Institut des NanoSciences de Paris, F-75005, Paris, France.
Published: January 2018
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Article Abstract
Scanning tunneling microscopy (STM), Auger electron spectroscopy (AES) and low energy electron diffraction have been used to follow the growth of Si films on Ag(111) at various temperatures. Using a simple growth model, we have simulated the distribution of film thickness as a function of coverage during evaporation, for the different temperatures. In the temperature regime where multilayer silicene has been claimed to form (470-500 K), a good agreement is found with AES intensity variations and STM measurements within a Ag surfactant mediated growth, whereas a model with multilayer silicene growth fails to reproduce the AES measurements.
Metal-oxide interfaces play a critical role in catalytic processes, such as methanol adsorption and decomposition reactions. In this work, we investigated methanol reactions on the inverse model CeO/Ag(111) catalyst surfaces, i.e.
Functional Nanomaterials Group and Catalysis Research Center, Department of Chemistry, TUM School of Natural Sciences, Technical University of Munich, Lichtenbergstr. 4, 85748 Garching, Germany.
Ultrathin two-dimensional silica films have been suggested as highly defined conductive models for fundamental studies on silica-supported catalyst particles. Key requirements in this context are closed silica films that isolate the gas phase from the underlying metal substrate and stability under reaction conditions. Here, we present silica bilayer films grown on Pt(111) and Rh(111) and characterize them by scanning tunneling microscopy and X-ray photoelectron spectroscopy.
Silicene, a two-dimensional (2D) Si monolayer with properties similar to those of graphene, has attracted considerable attention because of its compatibility with existing technology. Most growth efforts to date have focused on the Ag(111) substrate, with a 3 × 3 phase widely reported below one monolayer (ML). As the coverage increases, a √3 × √3 pattern frequently emerges, which has been proposed by various experimental investigations as a reconstructed structure.
Department of Chemistry and Biochemistry, Materials Science Institute, Oregon Center for Optical, Molecular, and Quantum Science, University of Oregon, 1253 University of Oregon, Eugene, Oregon 97403, United States.
Alkali halides are well-known for their tendency to form rock-salt-like crystal structures. Here we present a scanning tunneling microscopy study of a previously unreported alternative structure of one such alkali halide, RbI. When deposited on Ag(111) at a low submonolayer surface coverage, RbI forms islands with hexagonally coordinated atomic structures, in contrast to the expected rock-salt structures typically observed for such alkali halide films on metal surfaces.
While the crystal structure of the polymorph phase can be studied in three dimensions conveniently by X-ray methods like grazing-incidence X-ray diffraction (GIXD), the first monolayer is only accessible by surface-sensitive methods that allow the determination of a two-dimensional lattice. Here, GIXD measurements with sample rotation are compared with distortion-corrected low-energy electron diffraction (LEED) experiments on conjugated molecules: 3,4;9,10-perylenetetracarboxylic dianhydride (PTCDA), 6,13-pentacenequinone (P2O), 1,2;8,9-dibenzopentacene (trans-DBPen) and dicyanovinyl-quaterthiophene (DCV4T-Et2) grown by physical vapor deposition on Ag(111) and Cu(111) single crystals. For these molecular crystals, which exhibit different crystallographic lattices and crystal orientations as well as epitaxial properties, the geometric parameters of the three-dimensional lattice are compared with the corresponding geometry of the first monolayer.
