Dresden 2009 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 56: Metal substrates: Epitaxy, growth and adsorbates
O 56.12: Vortrag
Donnerstag, 26. März 2009, 17:45–18:00, SCH A316
Adsorption induced surface stress change of O and H on Pt(111) — •Zhen Tian, Dirk Sander, and Jürgen Kirschner — Max-Plank Institute of Microsctructure Physics, 06120, Halle, Germany
Surface stress changes induced by adsorption of oxygen and hydrogen on clean Pt(111) surface are measured in a UHV system with an optical beam bending method. Combined low energy electron diffraction (LEED) and stress measurements identify a compressive surface stress change of −2.2 N/m upon formation of a p(2×2)-O structure for an exposure of 120 L oxygen at 5×10−7 mbar at room temperature. The exposure of clean Pt(111) to H2 at PH2=5×10−7 mbar leads to a compressive surface stress change of −0.5 N/m, which saturates after 5 L. We found that the magnitude of the H-induced surface stress change depends on the H2 partial pressure. Exposure at higher partial pressure induces larger compressive stress change, e.g. partial pressure of PH2=5×10−6 mbar induces a compressive stress change of −0.73 N/m. These results are discussed in view of other experimental studies on surface stress[1] and calculations[2] on adsorbate-induced surface stress of Pt(111).
[1] A. Grossmann, W. Erley, and H. Ibach, Surf. Rev. Lett. 2 (1995) 543. [2] P. J. Feibelman, Phys. Rev. B, 56 (1997) 2175.