Abstract:
State-of-the-art ab-initio methods have matured to a complete tool-box for structure determination rivaling present-day experimental methods with respect to precision and reliability as corroborated by DFT calculations for the halogen/platinum adsorption system.

Br adsorbed on the strongly anisotropic Pt(110) surface forms a sequence of (n×1) structures, where Br is found in bridge sites on and between the close packed Pt rows. The preference for one site over the other could be explained by assuming short-range interactions, where adsorbate-adsorbate interactions mediated by quasi-one-dimensional surface resonances play an important role. From a technological point of view, the interaction of halogens with platinum surfaces is an extremely interesting problem, because halogens serve as platinum mobilizers in both, deposition and corrosion processes. [PtCl₄]^2- deposition from an electrolyte followed by reduction to metallic Pt clusters is a way to obtain highly dispersed catalytically active Pt surfaces. Interestingly, a dry deposition of Cl₂ in vacuo on the initially clean Pt(110) surface yields an almost identical array of Cl and PtCl₄ as the direct deposition of [PtCl₄]^2-, which indicates that the highly-ordered Cl/PtCl₄/metal system forms an universal transition state in both, erosion and deposition.