Water adsorption on Ge(100) : a computational study

• Cluster calculations simulating water dissociation on Ge(100) are presented. We evaluate the electronic structure of molecular water and dissociation products (OH, O, H) in a LCAO-X scheme. Ge 3d core level shifts were approximated by the ionization potentials (IPs) of nonbonding a2 orbitals. Finally, we discuss the nomenclature of hydroxyl groups ligated to different adsorbents. The germanium-adsorbate atomic distance and not simply the perpendicular position above the first Ge(100) layer was found to be the most important chemisorption parameter. This illustrates the importance of directional bonding and contrasts adsorption on metals. Adsorption at open bridge sites will give significantly less perturbation than adsorption at terminal sites. Major perturbations at the former site require movement of substrate atoms to accommodate the necessary short GeO distances. Our calculations suggest that (i) some water dissociation occurs already at 100 K, (ii) two different hydroxyl species are present at the surface, and (iii) one of the hydroxyl ligands is akin to adsorbed oxygen.

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NATURVETENSKAP  -- Fysik -- Annan fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Other Physics Topics (hsv//eng)

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Fysik

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