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O: Oberflächenphysik

O 18: Adsorption an Oberfl
ächen II

O 18.4: Vortrag

Samstag, 5. März 2005, 11:30–11:45, TU EB301

H on Pt(110): Atypical chemisorption site at low coverages, typical at high covarages? — •Rinaldo Zucca and Josef Redinger — Center f. Computational Materials Science, Vienna University of Technology, Getreidemarkt 9/134, A-1060 Vienna, Austria

A recent analysis of an hydrogen-modified Pt(110) surface with quantitative LEED and DFT calculations established a strong dependence of (1x2) missing row surface Pt lattice relaxations on the H atom coverage. Contrary to former assignments, both experiment and DFT calculations agree that at low coverages (β₂-state) H occupies adsorption sites above the outermost close-packed rows. A careful theoretical study of possible sites and trajectories revealed the short-bridge site on the outermost row, and not the fcc pseudo-threefold site at the (111) microfacets of the missing row surface’s deep troughs as the preferred chemisorption site. Possible adsorption sites and adsorbate structures at higher coverages, such as found in the β₁-state, are presently under investigation.