Berlin 2008 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 18: Poster Session I - MA 141/144 (Atomic Wires; Size-Selected Clusters; Nanostructures; Metal Substrates: Clean Surfaces+Adsorption of Organic / Bio Molecules+Solid-Liquid Interfaces+Adsorption of O and/or H; Surface or Interface Magnetism; Oxides and Insulators: Clean Surfaces)
O 18.36: Poster
Montag, 25. Februar 2008, 18:30–19:30, Poster F
SXPS studies of viologens adsorbed on a halogenide precovered Cu(100) electrode — •Stephan Breuer1, Thanh Pham Duc1, Sascha Hümann2, Peter Broekmann3, Ralf Hunger4, Thomas Mayer4, and Klaus Wandelt1 — 1Institut für Physikalische und Theoretische Chemie, Universität Bonn, Wegelerstr. 12, 53115 Bonn — 2Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Str. 1, 40237 Düsseldorf — 3BASF AG, G-CAE/WED - M320, 67056 Ludwigshafen — 4Institut für Materialwissenschaften, TU Darmstadt, c/o BESSY, Albert-Einstein-Str. 15, 12489 Berlin
We have studied the redox-chemistry of Dibenzyl(DBV)- and Diphenyl(DPV)-Viologenes adsorbed on a chloride and iodide precovered Cu(100) single crystal electrode using cyclic voltametry (CV), in-situ electrochemical scanning tunneling microscopy (ECSTM) and ex-situ X-ray photoelectron spectroscopy with synchrotron radiation at BESSY II (SXPS). From ECSTM it is known, that DBV undergoes a structural phase transition on the anion modified Cu(100) surface as a function of electrode potential. While a checkerboard like cavitand-structure at positive potentials is formed by DBV2+- dications a stripe-phase at negative potentials consists of DBV+·-radical cations. This assignment is supported by the N1s-electron binding energies of 402 eV (dications) and 400,7 eV (radical cations) as measured by SXPS. DPV forms only a stripe-phase of radical-cations consistent with a N1s energy of 400,6 eV. No additional chloride or iodide anions are intercalated within the respective viologene layer, as concluded from the Cl2p and I4d signals, respectively.