Regensburg 2010 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 27: Metal subtrates: Adsorption of O and/or H
O 27.1: Vortrag
Dienstag, 23. März 2010, 10:30–10:45, H42
New Surfaces Stabilized by Adsorbate-Induced Faceting of Ir(210) — •Payam Kaghazchi1, Ivan Ermanoski2, Wenhua Chen3, and Timo Jacob1 — 1Universität Ulm, Albert-Einstein-Allee 47, D-89069 Ulm, Germany — 2Sandia National Laboratories, USA — 3Rutgers University, Piscataway, NJ 08854, USA
When atomically-rough Ir(210) is exposed to more than 0.5 ML of oxygen and annealed to 600 K, nanoscale three-sided pyramidal facets grow and cover the surface. Experimental measurements revealed that these facets expose faces of Ir(311), Ir(311), and Ir(110) orientation. Furthermore, while the (311) and (311) faces are always smooth, some (110) faces were found to be partially rough [1]. As a combined effort of experiment (STM) and theory (DFT) we investigated the nature of these rough areas on the (110) faces. It was found that these regions consist of a complicated Ir(110) reconstruction, leading to a stepped double-missing-row (110) superstructure. Interestingly, while this structure is not observable on a Ir(110) single crystal surface, it only becomes thermodynamically favorable on the (110) faces of the nanopyramids formed after the oxygen-induced faceting of Ir(210). This indicates that with the aid of facet formation one can stabilize new surfaces, which cannot be stabilized neither by cleavage of a crystal nor through by reconstruction. [1] T. E. Madey, W. Chen, H. Wang, P. Kaghazchi, T. Jacob, Chem. Soc. Rev., 37, 2310 (2008).