title: Surface investigation of intermetallic PdGa(111).
abstract: The intermetallic PdGa is a highly selective and potent catalyst in the semihydrogenation of acetylene, which is attributed to the surface stability and isolated Pd atom ensembles. In this context PdGa single crystals of form B with (111) orientation were investigated by means of X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), scanning tunneling microscopy (STM), X-ray photoelectron diffraction (XPD), and low-energy electron diffraction (LEED) to study the electronic and geometric properties of this surface. UPS and thermal desorption spectroscopy (TDS) were used to probe the chemisorption behavior of CO. The PdGa(111) surface exhibits a (1 × 1) LEED and a pronounced XPD pattern indicating an unreconstructed bulk-truncated surface. Low-temperature STM reveals a smooth surface with a (1 × 1) unit cell. No segregation occurs, and no impurities are detected by XPS. The electronic structure and the CO adsorption properties reveal PdGa(111) to be a bulk-truncated intermetallic compound with Pd-Ga partial covalent bonding.
authors.affiliation: Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, Germany. dirkrose@fhi-berlin.mpg.de
authors.forename: Dirk
authors.initials: D
authors.lastname: Rosenthal
authors.forename: Roland
authors.initials: R
authors.lastname: Widmer
authors.forename: Ronald
authors.initials: R
authors.lastname: Wagner
authors.forename: Peter
authors.initials: P
authors.lastname: Gille
authors.forename: Marc
authors.initials: M
authors.lastname: Armbrüster
authors.forename: Yuri
authors.initials: Y
authors.lastname: Grin
authors.forename: Robert
authors.initials: R
authors.lastname: Schlögl
authors.forename: Oliver
authors.initials: O
authors.lastname: Gröning