Regensburg 2004 – wissenschaftliches Programm

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O: Oberflächenphysik

O 25: Epitaxie und Wachstum II

O 25.10: Vortrag

Dienstag, 9. März 2004, 18:00–18:15, H39

Growth of Cr on Ru(0001) studied by STM — •R. Denecke¹, M.P. Engelhardt¹, M. Schmid², A. Biedermann², P. Varga², and H.-P. Steinrück¹ — ¹Physikalische Chemie II, Universität Erlangen-Nbg., Egerlandstr. 3, 91058 Erlangen, Germany — ²Inst. f. Allgemeine Physik, Technische Universität Wien, Wiedner Hauptstr. 8- 10/134, 1040 Wien, Austria

We give an insight into the temperature dependent growth of Cr on Ru(0001) using scanning tunnelling microscopy (STM). At room temperature the growth is not purely layer-by-layer. Annealing of the resulting Cr layers to 500 and 700 K leads to the formation of Cr islands with a bcc(110)-like structure. A complete pseudomorphic Cr monolayer could be prepared for evaporation at 700 K. By applying a countervoltage at the end of the electron beam evaporator to suppress the Cr ions leaving the evaporator smoother Cr layers are obtained. The formation of a Cr-Ru surface alloy with a Cr:Ru ratio of 1:2 at 1000 K was observed; on this alloy CO molecules adsorb predominately at Ru sites in on top geometry. The conclusions are discussed in the light of Auger electron spectroscopy and temperature- programmed desorption results [1]. Supported by the Max-Buchner-Stiftung.

[1] M.P. Engelhardt et al., Surf. Sci. 512 (2002) 107.