A peculiar bonding of sulphur at the Nb(001) surfaceE. Hüger1, 2, M. Zelený3, 4, T. Kána5, 4, K. Osuch6, 7 and M. Sob8, 4
1 Institute of Physics, Technische Universität Clausthal - Clausthal-Zellerfeld, Germany, EU
2 Department of Biomaterials, iba eV Rosenhof - Heilbad Heiligenstadt, Germany, EU
3 Faculty of Chemistry, Brno University of Technology - Brno, Czech Republic, EU
4 Institute of Physics of Materials, Academy of Sciences of the Czech Republic - Brno, Czech Republic, EU
5 Faculty of Mechanical Engineering, Brno University of Technology - Brno, Czech Republic, EU
6 Department of Physics, University of South Africa - Unisa 0003, Pretoria, South Africa
7 Faculty of Physics, Warsaw University of Technology - Warszawa, Poland, EU
8 Department of Chemistry, Faculty of Science, Masaryk University - Brno, Czech Republic, EU
received 17 February 2008; accepted in final form 26 May 2008; published July 2008
published online 20 June 2008
The morphological, crystallographical and electronic structure of a well-ordered pseudomorphic sulphur monolayer (S ML) bonded at the (001) surface of a niobium substrate was investigated experimentally and theoretically. The system exhibits strong sulphur-niobium bonds with fourfold symmetry which do not exist in bulk niobium chalcogenides. These bonds enhance the localization of occupied bands near the Fermi energy in two Nb MLs under the S ML and, due to changed symmetry and stoichiometry, push the p-states of the S ML to deeper binding energies as compared to Nb chalcogenides. The S ML shows strong iono-covalent bonding to Nb(001) with bonding states mainly due to S-3p and antibonding states due to Nb-4d orbitals.
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.
© EPLA 2008