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 400^∘C and only minor changes are detected after annealing at 500^∘C. In an O₂ atmosphere, the particles are stable at room temperature, but grow dramatically after annealing to 400^∘C. In air, particle growth is observed already at RT, accompanied by the formation of Au-OH species. Possible mechanisms underlying these effects are discussed.