title: High chemical activity of a perovskite surface: reaction of CO with Sr(3)Ru(2)O(7).
abstract: Adsorption of CO at the Sr(3)Ru(2)O(7)(001) surface was studied with low-temperature scanning tunneling microscopy (STM) and density functional theory. In situ cleaved single crystals terminate in an almost perfect SrO surface. At 78 K, CO first populates impurities and then adsorbs above the apical surface O with a binding energy E(ads)=-0.7  eV. Above 100 K, this physisorbed CO replaces the surface O, forming a bent CO(2) with the C end bound to the Ru underneath. The resulting metal carboxylate (Ru-COO) can be desorbed by STM manipulation. A low activation (0.2 eV) and high binding (-2.2  eV) energy confirm a strong reaction between CO and regular surface sites of Sr(3)Ru(2)O(7); likely, this reaction causes the "UHV aging effect" reported for this and other perovskite oxides.
authors.affiliation: Institute of Applied Physics, Vienna University of Technology, Wiedner Hauptstraße 8-10, A-1040 Vienna, Austria.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Stöger
authors.affiliation: Institute of Applied Physics, Vienna University of Technology, Wiedner Hauptstraße 8-10, A-1040 Vienna, Austria and Center for Computational Materials Science, Vienna University of Technology, Gußhausstraße 25-25a, A-1040 Vienna, Austria.
authors.forename: Marcel
authors.initials: M
authors.lastname: Hieckel
authors.affiliation: Institute of Applied Physics, Vienna University of Technology, Wiedner Hauptstraße 8-10, A-1040 Vienna, Austria and Center for Computational Materials Science, Vienna University of Technology, Gußhausstraße 25-25a, A-1040 Vienna, Austria.
authors.forename: Florian
authors.initials: F
authors.lastname: Mittendorfer
authors.affiliation: Institute of Applied Physics, Vienna University of Technology, Wiedner Hauptstraße 8-10, A-1040 Vienna, Austria.
authors.forename: Zhiming
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Department of Physics and Engineering Physics, Tulane University, New Orleans, Louisiana 70118, USA.
authors.forename: David
authors.initials: D
authors.lastname: Fobes
authors.affiliation: Department of Physics and Engineering Physics, Tulane University, New Orleans, Louisiana 70118, USA.
authors.forename: Jin
authors.initials: J
authors.lastname: Peng
authors.affiliation: Department of Physics and Engineering Physics, Tulane University, New Orleans, Louisiana 70118, USA.
authors.forename: Zhiqiang
authors.initials: Z
authors.lastname: Mao
authors.affiliation: Institute of Applied Physics, Vienna University of Technology, Wiedner Hauptstraße 8-10, A-1040 Vienna, Austria.
authors.forename: Michael
authors.initials: M
authors.lastname: Schmid
authors.affiliation: Institute of Applied Physics, Vienna University of Technology, Wiedner Hauptstraße 8-10, A-1040 Vienna, Austria and Center for Computational Materials Science, Vienna University of Technology, Gußhausstraße 25-25a, A-1040 Vienna, Austria.
authors.forename: Josef
authors.initials: J
authors.lastname: Redinger
authors.affiliation: Institute of Applied Physics, Vienna University of Technology, Wiedner Hauptstraße 8-10, A-1040 Vienna, Austria.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Diebold