A search for surface alloy formation in faceting induced by monolayer metal films: Pd/W (111) and Ni/W (111)
Abstract
A monolayer of Pd on a W (111) surface will cause faceting of the surface upon annealing to T > 700 K, with the formation of {211} oriented microfacets. In order to learn whether surface alloy formation or intermixing of surface layers occurs during faceting we have employed low energy ion scattering (LEIS) , low energy electron diffraction (LEED) and X-ray photoelectron spectroscopy (XPS) to investigate the Pd/W (111) system. We find that 3.0 Å Pd deposited at room temperature almost completely covers the substrate W. In the temperature range from room temperature to ∼ 1125 K (the onset of Pd desorption) there is no intermixing of Pd atoms with W atoms: Pd atoms stay on top of the planar surface as well as the faceted surface. In comparison with the Pd/W(111) system, we have also studied the Ni/W (111) system which does not exhibit faceting behavior. Within experimental uncertainty we find that there is 10% intermixing of Ni atoms with W atoms in the topmost surface layer, after annealing at 1175 K.
- Publication:
-
Surface Science
- Pub Date:
- January 1995
- DOI:
- 10.1016/0039-6028(95)90032-2
- Bibcode:
- 1995SurSc.322..221D