Dresden 2017 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 87: Metal Substrates: Structure, Epitaxy and Growth
O 87.8: Vortrag
Donnerstag, 23. März 2017, 12:30–12:45, WIL C307
Transformation of the Pt(001)-hex to a smooth and clean Pt(001)-(1x1) — Rene Hammer1, Florian Schumann1, •Oliver Krahn1, Stefan Förster1, Klaus Meinel1, and Wolf Widdra1,2 — 1Institute of Physics, Martin-Luther-Universität Halle-Wittenberg, D-06099 Halle, Germany — 2Max-Planck Institut für Mikrostrukturphysik, D-06120 Halle, Germany
The quasihexagonal reconstruction of the (001) surfaces of gold and platinum have been under intense investigation for decades. Yet the non-reconstructed (1x1) structure is important for particular applications. Here, we study by STM, SPA-LEED and HREELS the structural transformation of the Pt(001)-hex to an unreconstructed (1x1) surface by gas adsorption. The lifting of the hex occurs along the reconstruction rows. Surplus Pt atoms are pushed on top of the surface leading to one-dimensional chains growing along [110] at low temperatures (77 K). These chains decay into islands at room temperature and result in a roughening of the Pt(001)-(1x1) surface. Surface smoothing by intralayer diffusion above 150 ∘C fails because the hex layer recovers from the islands. Island growth is only attained by step edge diffusion at around 100 ∘C promoting a Smoluchowski ripening of the islands. When island size reaches 10 nm, Ostwald ripening at 350 ∘C can be applied. This leads to a smooth surface with large two-dimensional islands. Finally an annealing process at 150 ∘C in O2 atmosphere results in a well-ordered and adsorbate-free (1x1) surface.