Dresden 2014 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 82: Metal Substrates II
O 82.6: Vortrag
Donnerstag, 3. April 2014, 17:15–17:30, WIL A317
Origin of unexpected attractive adsorbate-adsorbate interactions between negatively charged ions on Mg(0001) surfaces — Su-Ting Cheng, •Mira Todorova, and Jörg Neugebauer — Max-Planck-Institut für Eisenforschung, Düsseldorf
Electrostatic repulsion usually leads to an increase in work function and a decrease in binding energy when the coverage of electronegative elements adsorbed on a metal surface is increased. Using density-functional theory we investigate the adsorption of {N,O,F,Cl} on Mg(0001) and find that only Cl complies with this expectations. All the considered 2nd row elements cause a decrease in work-function and an increase in binding energy with increasing coverage. We show that these counter-intuitive phenomena can be understood in terms of an efficient embedding of the adsorbate atoms into the unusually large electronic surface spill-out of Mg(0001). The described mechanism is based on purely electrostatic arguments and thus expected to be a generic feature on surfaces consisting of highly electropositive elements.