Dresden 2006 – wissenschaftliches Programm
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O: Oberflächenphysik
O 29: Poster session II (Nanostructures, Magnetism, Particles and clusters, Scanning probe techniques, Time-resolved spectroscopy, Structure and dynamics, Semiconductor surfaces and interfaces, Oxides and insulators, Solid-liquid interfaces)
O 29.24: Poster
Mittwoch, 29. März 2006, 14:30–17:30, P2
Oxidation of Au/Ag-nanoparticles and clusters on HOPG/SiO2 surfaces — •Rainer Dietsche, Dong Chan Lim, Moritz Bubek, Ignacio Lopez-Salido, Young Dok Kim, and Gerd Ganteför — Fachbereich Physik, Universität Konstanz, 78464 Konstanz
Au nanostructures were prepared on HOPG and SiO2 surfaces. Size distribution was studied using STM. Oxidation and reduction of the particles was performed with atomic oxygen and carbonmonoxide under UHV conditions. XPS spectra of the Au 4f level show different behaviour depending on particle size.
On HOPG Au nanoparticles smaller than ∼10 nm two different oxygen species were detected, suggested to be Au-oxide and subsurface oxygen. Both species show different reactivity towards CO.
On silica layers the oxidation/reduction behaviour of Au nanoparticles show a strong size dependency. Larger particles exhibit additional features of the Au 4f level. Whereas particles smaller than ∼7 nm in height show a much less reactive type of Au-O bond.
Au and Ag clusters were deposited and studied with the same method. Small Au clusters on SiO2 show a significant even-odd size dependency in CO oxidation.
[1] Lim, Lopez-Salido, Dietsche, Bubek and Kim, Oxidation of Au nanoparticles on HOPG using atomic oxygen, accepted for publication in Surface Science, 2005
[2] Lim, Lopez-Salido and Kim, Size-selectivity for CO-oxidation of Ag nanoparticles on HOPG, Surface Science, available on-line
[3] Lopez-Salido, Lim and Kim, Surface Science, 588 (1-3) 6-18, 2005