Dresden 2014 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 50: Oxide and Insulator Surfaces I
O 50.1: Vortrag
Mittwoch, 2. April 2014, 10:30–10:45, WIL A317
Elementary steps of water dissociation on α-Al2O3(0001) — •Harald Kirsch1, Jonas Wirth2, Yujin Tong1, Martin Wolf1, Peter Saalfrank2, and R. Kramer Campen1 — 1Fritz-Haber-Institut, Abt. Physikalische Chemie, 14195 Berlin, Germany — 2Universitaet Potsdam, Institut fuer Chemie, 14476 Potsdam OT Golm, Germany
Alumina surfaces are ubiquitous in technologically relevant applications and a useful model system for more complicated, environmentally abundant, alumino-silicate phases. Because their properties change dramatically on interaction and reaction with water, water/Alumina chemistry has been studied, both experimentally and theoretically, for decades. In this work, we study the interaction of heavy water (D2O) with the α-Al2O3(0001) surface under ultra high vacuum (UHV) conditions. Hydroxylation of the Al2O3(0001) in UHV is performed by dosing D2O seeded in Helium with a molecular beam source (MBS). For characterization we employ vibrationally resonant sum frequency generation (VSF) spectroscopy to probe the OD stretch response of interfacial species. This technique allows us to distinguish several different OD-species in the OD-stretching region. Comparison of the resulting measured spectra with frequencies and geometries claculated from periodic density functional theory allows us to identify, for the first time, the products of the two theoretically predicted dissociation pathways: we observe the elementary steps of water dissociation on α-Al2O3(0001).