Regensburg 2004 – wissenschaftliches Programm

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O: Oberflächenphysik

O 14: Postersitzung (Adsorption an Oberflächen, Epitaxie und Wachstum, Organische Dünnschichten, Oxide und Isolatoren, Phasenübergänge, Rastersondentechniken, Struktur und Dynamik reiner Oberflächen)

O 14.8: Poster

Montag, 8. März 2004, 18:00–21:00, Bereich C

Growth and thermal stability of Ni adsorption layers on the (111) Mo crystal surface — •Cezary Tomas1,2, Jan Kolaczkiewicz1, and Herbert Pfnür21Institute of Experimental Physics, University of Wroclaw, Poland — 2Institut Für Festkörperphysik, Universität Hannover, Germany

The low-density (111) surfaces of bcc metals have a high surface free energy and undergo faceting at sufficiently high temperatures, when covered with a chemisorbed layer. However, not all chemisorbed adsorbates lead to this process. Madey and coworkers have studied the reconstruction of the W(111) surface. They found that faceting occurs in the presence of metals with electronegativity 2 or more on the Pauling scale. Our results do not support this classification. We suggest that the major cause of faceting is the adsorbate-substrate and adsorbate-adsorbate interaction and the magnitude of the atomic radii of the adsorbate and substrate. The goal of this study was to investigate the growth mechanism and the thermal stability of Ni layers adsorbed on the (111) Mo surface. AES, LEED, Δ φ and STM has been used in this work. We find that Ni does not cause faceting. Only for coverages Θ > 3 ML 3D crystallites appear on the surface and pass into 2D forms with increasing temperature.

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