title: Observation of all the intermediate steps of a chemical reaction on an oxide surface by scanning tunneling microscopy.
abstract: By means of high-resolution scanning tunneling microscopy (STM), we have revealed unprecedented details about the intermediate steps for a surface-catalyzed reaction. Specifically, we studied the oxidation of H adatoms by O(2) molecules on the rutile TiO(2)(110) surface. O(2) adsorbs and successively reacts with the H adatoms, resulting in the formation of water species. Using time-lapsed STM imaging, we have unraveled the individual reaction intermediates of HO(2), H(2)O(2), and H(3)O(2) stoichiometry and the final reaction product-pairs of water molecules, [H(2)O](2). Because of their different appearance and mobility, these four species are discernible in the time-lapsed STM images. The interpretation of the STM results is corroborated by density functional theory calculations. The presented experimental and theoretical results are discussed with respect to previous reports where other reaction mechanisms have been put forward.
authors.affiliation: Interdisciplinary Nanoscience Center (iNANO), Aarhus University, DK-8000 Aarhus C, Denmark.
authors.forename: Jesper
authors.initials: J
authors.lastname: Matthiesen
authors.forename: Stefan
authors.initials: S
authors.lastname: Wendt
authors.forename: Jonas Ø
authors.initials: JØ
authors.lastname: Hansen
authors.forename: Georg K H
authors.initials: GK
authors.lastname: Madsen
authors.forename: Estephania
authors.initials: E
authors.lastname: Lira
authors.forename: Patrick
authors.initials: P
authors.lastname: Galliker
authors.forename: Ebbe K
authors.initials: EK
authors.lastname: Vestergaard
authors.forename: Renald
authors.initials: R
authors.lastname: Schaub
authors.forename: Erik
authors.initials: E
authors.lastname: Laegsgaard
authors.forename: Bjørk
authors.initials: B
authors.lastname: Hammer
authors.forename: Flemming
authors.initials: F
authors.lastname: Besenbacher