Observation and destruction of an elusive adsorbate with STM: O₂/TiO₂(110)
Philipp Scheiber1, Alexander Riss, Michael Schmid
1Institute of Applied Physics, Vienna University of Technology, Wiedner Hauptstrasse 8-10, 1040 Vienna, Austria.
Abstract:
When a slightly defective rutile TiO₂(110) surface is exposed to O₂at elevated temperatures, the molecule dissociates at defects, filling O vacancies (V(O)) and creating O adatoms (O(ad)) on Ti(5c) rows. The adsorption of molecular O₂ at low temperatures has remained controversial. Low-temperature scanning tunneling microscopy of O₂, dosed on TiO₂(110) at a sample temperature of ≈100 K and imaged at 17 K, shows a molecular precursor at V(O) as a faint change in contrast. The adsorbed O₂ easily dissociates during the STM measurements, and the formation of O(ad)'s at both sides of the original V(O) is observed.
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