Berlin 2005 – wissenschaftliches Programm
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O: Oberflächenphysik
O 14: Struktur und Dynamik reiner Oberfl
ächen
O 14.3: Vortrag
Freitag, 4. März 2005, 16:15–16:30, TU EB407
Atomically resolved imaging of Stoichiometric CeO2 (111) — •S. Gritschneder1, Y. Namai2, A.S. Foster3, Y. Iwasawa2, and M. Reichling1 — 1Fachbereich Physik, Universität Osnabrück, Barbarastraße 7, 49076 Osnabrück, Germany — 2Department of Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan — 3Laboratory of Physics, University of Helsinki, P.O. Box 1100, 02015 HUT, Finland
The (111) surface of CeO2 in various oxidation states is important for catalytic activity and some of its details relating to surface oxygen atoms have already been studied with dynamic scanning force microscopy. For an in-depth understanding of the surface chemistry of CeO2(111), it is most interesting to gain insight into the details of surface structural features and to yield an unambiguous interpretation of contrast features observed in dynamic scanning force microscopy results obtained on CeO2(111). While atomic resolution can routinely be achieved nowadays, interpretation of atomic contrast images is still a non-trivial task. As CeO2 exhibits the same fluorite structure as the prototype material CaF2 and contrast formation on CaF2(111) is quantitatively well understood, we compare atomic contrast formation on both surfaces. On flat terraces, surface ions mostly appear as disk-like features but also other contrast feature like triangular patterns are observed. When scanning at smallest distance, the predominant contrast pattern is a stable honeycomb structure. By theoretical modelling of the imaging process we aim to assign the different contrast patterns to the anionic and the cationic sub-lattices, respectively.