Regensburg 2007 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 44: Poster Session II (Semiconductors; Oxides and Insulators: Adsorption, Clean Surfaces, Epitaxy and Growth; Surface Chemical Reactions and Heterogeneous Catalysis; Surface or Interface Magnetism; Solid-Liquid Interfaces; Organic, Polymeric, Biomolecular Films; Particles and Clusters; Methods: Atomic and Electronic Structure; Time-resolved Spectroscopies)
O 44.60: Poster
Mittwoch, 28. März 2007, 17:00–19:30, Poster C
α-Fe2O3 (0001) surface structure analysis by LEED — •Maike Lübbe and Wolfgang Moritz — LMU, Department für Geo- und Umweltwissenschaften, Theresienstr. 41, D-80333 München
Despite the importance of the haematite, α-Fe2O3, surface in chemical and technological applications its structure has not been determined unambiguously up to now although being subject to both theoretical [1, 2] and experimental [3, 4] investigations.
We therefore analysed the (1×1) (0001) surface structure of a bulk α-Fe2O3 crystal by low energy electron diffraction.
The polished crystal was installed in an UHV chamber with a base pressure of 2 · 10−10 mbar and annealed at 500∘C in an O2 atmosphere, pO2 ≈ 3 · 10−8 mbar, for several hours. The diffraction spots were sharp although a somewhat elevated diffuse background was observed. An I-V-curve data set of 10 symmetrically independent diffraction spots was measured at room temperature in the energy range E ≈ 150 … 500 eV. Measurements at lower electron energies were not possible due to charging effects of the insulating crystal.
Our analysis indicates that the α-Fe2O3 (0001) surface is terminated by iron partially occupying two bulk sites when prepared at low oxygen pressure. Relaxation effects along c-axis are quite large and involve several iron double layers.
[1] A. Rohrbach et al., Phys. Rev. B 70, 125426 (2004) [1] W. Bergermayer, H. Schweiger, Phys. Rev. B 69, 195409 (2004) [3] G. Ketteler et al., Surf. Rev. Lett. 8, 661 (2001) [4] S. Chambers, S. Yi, Surf. Sci. Lett. 439, L785 (1999)