Abstract: Surf. Sci. 454-456 (2000) 88-93
A. Menzel, K. Swamy, R. Beer, P. Hanesch, E. Bertel, and
Electronic Structure of a Catalyst Poison: Br/Pt(110)
Surf. Sci. 454-456 (2000) 88-93.
[May 20, 2000]
The system Br/Pt(110) is studied by scanning tunneling microscopy, low energy electron diffraction, angle resolved photoemission and self-consistent ab initio calculations. Bromine is molecularly adsorbed at 300K, but dissociates at T>400K. The Br atoms adsorb substitutionally and form quasi-one-dimensional (1D) Pt-Br-Pt chains. The 1D character of the chains gives rise to a charge density wave ground state, which can be triggered by surface doping. A Fermi surface yielding an appropriate nesting vector is identified by photoemission. Furthermore, a Br-induced lowering of Pt d-bands is observed, which accounts in part for the halogen-induced poisoning. The Pt-Br bond is shown to be essentially covalent, ruling out electrostatic poisoning mechanisms.