Dresden 2014 – scientific programme
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O: Fachverband Oberflächenphysik
O 36: Posters: Bio/organic Molecules on Surfaces, Graphene, Solid/liquid interfaces, Metal Substrates, Electronic Structure Theory
O 36.76: Poster
Tuesday, April 1, 2014, 18:30–22:00, P1
Preparation of smooth and unreconstructed Pt(100)-(1x1) — •Klaus Meinel1, Florian Schumann1, Benjamin Köhler1, and Wolf Widdra1,2 — 1Institute of Physics, Martin-Luther-Universität Halle-Wittenberg, Halle, Germany — 2Max-Planck Institut für Mikrostrukturphysik, Halle, Germany
Pt(100) is known for its Pt(100)-hex reconstruction where a compressed quasihexagonal top layer is formed. For specific applications, the non-reconstructed quadratic (1×1) structure is desired. Surface reconstruction can be lifted by adsorbates. Using HREELS and LEED we show that upon exposure to Ar sputter gas in the presence of electrons an effective C2Hx adsorption takes place from the background which immediate lifts reconstruction. In STM, the resulting (1×1) surface appears extremely rough due to numerous two-dimensional islands (size 3 nm) formed by the surplus Pt atoms. Surface smoothing by intralayer diffusion at temperatures above 300 ∘C fails as the surface reconstruction recovers from small islands. Surface smoothing without reconstruction is attained by activating step edge diffusion at temperatures around 100 ∘C which promotes Smoluchowski ripening of the islands. When the island size increases to about 10 nm, islands no longer promote the surface reconstruction and allow pronounced Ostwald ripening even at temperatures around 450 ∘C. This yields a smooth surface which displays only large 2D islands. During annealing the surface remains covered by C2Hx showing after Ostwald ripening a (√2×2√2)R45∘ structure. Final cleaning is attained by annealing in O2 atmosphere at 150 ∘C at which adsorbates desorb as CO and H2O.