Regensburg 2004 – wissenschaftliches Programm

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O: Oberflächenphysik

O 24: Nanostrukturen II

O 24.9: Vortrag

Dienstag, 9. März 2004, 17:45–18:00, H38

Stability of Au nanoparticles on fully oxidized TiO2 substrates. An AFM/XPS study of Au/TiO2 model systems — •Stefan Kielbassa, Markus Kinne, and Rolf-Jürgen Behm — Abt. Oberflächenchemie und Katalyse, Univ. Ulm, 89069 Ulm

The stability of nm-sized gold particles deposited on fully oxidized TiO2(110) substrates under ultra-high vacuum (UHV) conditions, in an O2 atmosphere and in air was examined with atomic force microscopy (AFM) and x-ray photoelectron spectroscopy (XPS). Au/TiO2 model systems were prepared by evaporating submonolayers of gold on fully stoichiometric and atomically smooth TiO2 rutile (110) substrates. The thermal stability of the particles is found to strongly depend on the reaction atmosphere. Under UHV conditions, the particles are stable even after annealing at 400C and only minor changes are detected after annealing at 500C. In an O2 atmosphere, the particles are stable at room temperature, but grow dramatically after annealing to 400C. In air, particle growth is observed already at RT, accompanied by the formation of Au-OH species. Possible mechanisms underlying these effects are discussed.

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