Making a noble metal ofE. Hüger1 and K. Osuch2, 3
1 Institute of Physics, Technische Universität Clausthal D-38678 Clausthal-Zellerfeld, Germany
2 Department of Physics, University of South Africa - Unisa 0003, South Africa
3 Faculty of Physics, Warsaw University of Technology Koszykowa 75, 00-662 Warsaw, Poland
received 2 March 2005; accepted in final form 18 May 2005
published online 15 June 2005
We present theoretical and experimental data concerning the possibility of inducing in properties characteristic of a noble metal. A free-standing monolayer expanded to the lattice constant of 3.30 exhibits an atomic-like electronic structure, having its d-valence states almost full, like the noble metals , or . To prevent de-population of the d-states, we deposit the ML on a substrate passivated by a pseudomorphic monolayer. The weak interaction with the -capped surface causes the centre of the d-states of the monolayer to lie much closer to the Fermi level than in bulk . As a result, the weakly bonded monolayer becomes more reactive than bulk . However, when is deposited directly on the surface, the strong, direct bonds between and push the d-band centre of the monolayer toward lower binding energies, resulting in reactivity comparable to that of the noble metal .
68.43.-h - Chemisorption/physisorption: adsorbates on surfaces.
82.80.Pv - Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.).
73.20.At - Surface states, band structure, electron density of states.
© EDP Sciences 2005