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O: Fachverband Oberflächenphysik

O 64: Oxides and Interfaces: Adsorption II

O 64.7: Vortrag

Mittwoch, 9. März 2016, 16:30–16:45, H6

CO₂ and Water Adsorption on the Fe₃O₄(001) Surface — •Jiri Pavelec, Jan Hulva, Roland Bliem, Oscar Gamba, Daniel Halwidl, Martin Setvin, Michael Schmid, Ulrike Diebold, and Gareth Parkinson — TU Wien, Vienna, Austria

The recently solved Fe₃O₄(001) surface [1] is an exciting model system to investigate catalysis by supported single atoms [2] and sub-nano clusters [3]. However, understanding the interaction of the clean surface with the relevant molecules is an essential prerequisite to studying such composite systems.

Here we report a study of water and CO₂ adsorption using a new multi-technique vacuum system constructed at the TU Wien that combines molecular beam methods, UPS, XPS and TPD. Together with STM results these data are used to characterize the state of the molecules over a broad temperature range (50K - 600K).

CO₂ is physisorbed up to 115K, and desorbs with first-order kinetics from regular lattice sites. A small peak at 125K provides a quantitative measure of the surface defect concentration.

Water adsorbs molecularly at 100K, and most of the molecules in the first monolayer desorb in four peaks up to 250 K. Isotopic labelling suggest that the two smaller peaks at 320K and 520K are related to defects, the latter involving exchange of O with the surface.

[1] R. Bliem et al., Science 2014, doi:10.1126/science.1260556

[2] Parkinson et al., Nature Materials 2013, doi:10.1038/nmat3667

[3] R. Bliem et al., Angewandte Chemie 2015, doi:10.1002/anie.2015073686