Physik: DPG Tagungen - Sitzung O 28 - Nano-science.de

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Physik: DPG Tagungen - Sitzung O 28 http://www.dpg-tagungen.de/archive/2004/o_28.html Surface Plasmon Propagation In Metallic Nanostructures •Phillip Olk 1 , Jan Seidel 1 , Stefan Grafström 1 , Eng Lukas 1 , Fadi Baida 2 , Daniel Van Labeke 2 , Marcell Ott 3 und Lothar Bischoff 4 1 Institut für Angewandte Photophysik, TU Dresden, 01062 Dresden 2 Laboratoire d'Optique P.M. Duffieux, CentreNational de La Recherche Scientifique, Unité Mixte deRecherche 6603, Université de Franche-Comté, F-25030Besançon Cedex, France 3 Organic Chemistry III / Macromolecular Chemistry, Universität Ulm, 89081 Ulm 4 Research Center Rossendorf, Institute of Ion BeamPhysics and Materials Research, 01314 Dresden Propagation of surface plasmons in metallic nanostructures and their interaction with defined surface features are presented. We use near-field optical methods in order to reveal various properties of such travelling surface waves, like optical transmission across barriers or coupling to free space electromagnetic waves. These characteristics are directly determined using an attenuated-total-reflection (ATR) excitation scheme together with dielectric fiber probes for near-field optical detection. We show results on plasmon propagation in self-assembled cluster films, discussing propagation lengths and resonance conditions. Furthermore, we present an experimental and theoretical analysis of plasmon mode coupling in continuous metallic films mediated by a single groove structure produced by focused ion beam (FIB) writing. O 28.55 Poster Mi 16:00 Bereich C Optical anisotropy of Cs nanostructure formation on GaAs(110), InP(110) and InAs(110) •Karsten Fleischer 1,2 , Gianlorenzo Bussetti 2 , Claudio Goletti 2 , Pierro Chiaradia 2 und Wolfgang Richter 1,2 2 Universitá ``Tor Vergata'', Dipartimento di Fisica, Via Ricerca Scientifica 1, 00133 Roma, Italy 1 TU-Berlin, Institut für Festkörperphysik, Hardenbergstr. 36, 10623 Berlin, Germany We present reflectance anisotropy spectra (RAS) of Cs covered GaAs, InP and InAs cleaved (110) surfaces. In such systems Cs forms one dimensional wirelike structures at low coverages. For the first time we studied the formation of these wires in situ with optical and therefore nondestructive techniques. Wire formation is accompanied with characteristic minima in the RAS spectra between the E 0 + ∆ 0 and E 1 bulk critical point. With growing coverages (θ > 0.3 ML) and formation of the two dimensional closed Cs layer (θ ? 0.5 ML), changes in the Cs related minima occur. Different wire types and also the transition into the disordered Cs double layers at saturation coverage ( θ ? 1 ML) can be monitored optically. O 28.56 Poster Mi 16:00 Bereich C Methanol oxidation on clean and oxygen-covered copper surfaces •Sung Sakong und Axel Groß Physik-Department T30, Technische Universität München, 85747 Garching, Germany We have studied methanol oxidation steps over clean and oxygen-covered copper surfaces by density functional theory (DFT) calculations. The reaction pathways are determined by the nudged elastic band (NEB) method [1] which in particularly also yields the intermediate states and the reaction barriers. We find that on clean copper surfaces, methanol is only weakly bound. The decomposition into methoxy and hydrogen is activated. Upon heating, methanol rather desorbs than dissociates. The further decomposition of adsorbed methoxy into formaldehyde and hydrogen is hindered by large barriers ( ? 1.5eV). The surface intermediate states in the methanol oxidation are significantly stabilised by co-adsorbed oxygen. The DFT calculations show that on oxygen-covered Cu(110), methanol dissociates spontaneously because of the strong attraction between the methanol hydroxyl hydrogen and the surface oxygen. The reaction steps are analysed in terms of the underlying electronic structure. Our calculations confirm the importance of co-exposed oxygen in the methanol oxidation on copper surfaces found in experiments (see, e.g., [2]). 20 of 32 07.06.2009 22:14
Physik: DPG Tagungen - Sitzung O 28 http://www.dpg-tagungen.de/archive/2004/o_28.html [1] G. Henkelman and H. Jónsson, J. Chem. Phys. 113, 9978 (2000). [2] Ch. Ammon et al., Surf. Sci. 507, 845 (2002). O 28.57 Poster Mi 16:00 Bereich C Electron Solvation during the Interaction of Na Atoms with Polar Molecules •A. Borodin 1 , O. Höfft 1 , U. Kahnert 1 , V. Kempter 1 , Y. Ferro 2 und A. Allouche 2 1 Institut für Physik und Physikalische Technologien, TU Clausthal, Leibnizstr. 4, D-38678 Clausthal-Zellerfeld 2 Physique des Interactions Ioniques et Moléculaires, CNRS-UMR6633 Campus Universitaire de Saint Jérôme, Marseille France The interaction of Na atoms with molecular films (H 2 O; CH 3 OH; NH 3 ) was studied with metastable impact electron spectroscopy (MIES) under UHV conditions. The films were grown at 90K, and exposed to Na. The spectral feature from 3sNa ionization occurs at an energetic position different from that found for metals or semiconductors. The results are compared with DFT calculations. Experiment and theory agree in the energetic positions of the main spectral features from the molecular and sodium ionization. The calculations suggest that the 3sNa emission observed experimentally originates from solvated 3s electrons which are located far from the Na-core and become stabilized by solvent molecules. The simultaneous emergence of emission from OH (or CH 3 O) and from solvated 3s electrons suggests that the delocalization and, consequently, the solvation play an important role in the Na-induced formation of CH 3 O and OH species from methanol and water, respectively. O 28.58 Poster Mi 16:00 Bereich C Spectral evidence for oxide free incorporation of oxygen into Ru(0001) •Raoul Blume 1 , Artur Böttcher 2 , Horst Conrad 3 und Horst Niehus 1 1 Institut für Physik, HU-Berlin, Newtonstr. 15, 12489 Berlin 2 Institut für Physikalische Chemie, Universität Karlsruhe, Kaiserstr. 12, 76131 Karlsruhe 3 Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin The capability of a smooth and defected Ru(0001) surface towards the oxygen accumulation has been studied by the means of thermal desorption spectroscopy (TDS) and the high resolution scanning XPS (Elettra, Trieste). By applying a soft Ar + -sputtering procedure individual surface defects confined to the two outermost Ru layers were created. The oxidation procedure applied here assures an incorporation of oxygen atoms in the subsurface region up to 4 monolayer equivalents (MLE) without any traces of RuO 2 -domains (high-pressure and low-temperature surface oxidation). By measuring the temperature and exposure dependence of the oxygen incorporation and analyzing the corresponding evolution of the Ru 3d 5/2 band we found characteristic electronic signatures allowing to distinguish oxygen atoms occupying the Ru(I)-Ru(II) interlayer space and oxygen species associated with surface defects. This assignment is supported by mesoscopic-scale surface images as well as the quantitative O 2 -TD analysis. O 28.59 Poster Mi 16:00 Bereich C Investigation of Au electrodeposition processes on metal single crystal surfaces •Ahmed Ayyad, Jochim Stettner und Olaf Magnussen Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität Kiel, Leibnizstraße 19, 24098 Kiel Metal electrodeposition processes have been a subject of substantial basic research during the last years, motivated by current technologies as well as future applications, such as the electrochemical formation of ultrathin layers and nanostructures. A major, largely unsettled question is how the electrode surface structure 21 of 32 07.06.2009 22:14
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