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O: Oberflächenphysik
O 26: Postersitzung (Rastersondentechniken, Nanostrukturen, Teilchen und Cluster, Methodisches, Oxide und Isolatoren, Grenzfl
äche fest-flüssig, Struktur und Dynamik reiner Oberfl
ächen, Oberfl
ächenreaktionen, Zeitaufg. Spektroskopie, Phasenüberg
änge
O 26.59: Poster
Mittwoch, 13. März 2002, 14:30–17:30, Bereich C
Revealing structure, order and disorder on high temperature reconstructed Al2O3(0001) — •Lutz Tröger, Clemens Barth, and Michael Reichling — Department Chemie, Universität München, Butenandtstraße 5-13. 81377 München, Deutschland
High resolution scanning force imaging on surfaces of bulk insulating oxide crystals has been found to be extremely difficult and, despite many attempts in that direction, atomic resolution has not been demonstrated for such systems. This barrier has been overcome and as an example we present results obtained on Al2O3(0001) in its (√31 x √31) R90 high temperature reconstruction. High resolution imaging reveals the reconstruction of the surface in form of a grid enclosing rhombi with sides along the unit cell vectors of the reconstructed structure. We show that the topmost surface layer has mainly hexagonal order but also areas that are much less well ordered. After extended exposure to water vapour, we observe well ordered hexagonal arrangements of defects decorating the corners of the reconstruction rhombi. We interpret the defects to be a result of dissociative water adsorption decorating the surface with hydroxyl clusters in form of small crystallites.