title: Atomic species identification at the (101) anatase surface by simultaneous scanning tunnelling and atomic force microscopy.
abstract: Anatase is a pivotal material in devices for energy-harvesting applications and catalysis. Methods for the accurate characterization of this reducible oxide at the atomic scale are critical in the exploration of outstanding properties for technological developments. Here we combine atomic force microscopy (AFM) and scanning tunnelling microscopy (STM), supported by first-principles calculations, for the simultaneous imaging and unambiguous identification of atomic species at the (101) anatase surface. We demonstrate that dynamic AFM-STM operation allows atomic resolution imaging within the material's band gap. Based on key distinguishing features extracted from calculations and experiments, we identify candidates for the most common surface defects. Our results pave the way for the understanding of surface processes, like adsorption of metal dopants and photoactive molecules, that are fundamental for the catalytic and photovoltaic applications of anatase, and demonstrate the potential of dynamic AFM-STM for the characterization of wide band gap materials.
authors.affiliation: 1] National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba 305-0047, Japan [2] Charles University, Faculty of Mathematics and Physics, V Holešovičkách 2, Praha 8, Czech Republic.
authors.forename: Oleksandr
authors.initials: O
authors.lastname: Stetsovych
authors.affiliation: Departamento de Física Teórica de la Materia Condensada, Universidad Autónoma de Madrid, Madrid 28049, Spain.
authors.forename: Milica
authors.initials: M
authors.lastname: Todorović
authors.affiliation: 1] National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba 305-0047, Japan [2] JST, PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan.
authors.forename: Tomoko K
authors.initials: TK
authors.lastname: Shimizu
authors.affiliation: 1] International Center for Young Scientists, NIMS, 1-2-1 Sengen, Tsukuba 305-0047, Japan [2] Catalan Institute of Nanoscience and Nanotechnology (ICN2), Bellaterra, Barcelona 08193, Spain.
authors.forename: César
authors.initials: C
authors.lastname: Moreno
authors.affiliation: International Center for Young Scientists, NIMS, 1-2-1 Sengen, Tsukuba 305-0047, Japan.
authors.forename: James William
authors.initials: JW
authors.lastname: Ryan
authors.affiliation: 1] National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba 305-0047, Japan [2] Karlsruhe Institute of Technology (KIT), Wolfgang Gaede Str. 1, Karlsruhe 76131, Germany.
authors.forename: Carmen Pérez
authors.initials: CP
authors.lastname: León
authors.affiliation: National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba 305-0047, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Sagisaka
authors.affiliation: 1] Institute of Chemical Research of Catalonia, Av. Països Catalans 16, Tarragona 43007, Spain [2] ICREA, Passeig Lluís Companys 23, Barcelona 08010, Spain.
authors.forename: Emilio
authors.initials: E
authors.lastname: Palomares
authors.affiliation: Charles University, Faculty of Mathematics and Physics, V Holešovičkách 2, Praha 8, Czech Republic.
authors.forename: Vladimír
authors.initials: V
authors.lastname: Matolín
authors.affiliation: National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba 305-0047, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Fujita
authors.affiliation: 1] Departamento de Física Teórica de la Materia Condensada, Universidad Autónoma de Madrid, Madrid 28049, Spain [2] Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, Madrid 28049, Spain.
authors.forename: Ruben
authors.identifier: 000000015896541X
authors.initials: R
authors.lastname: Perez
authors.affiliation: National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba 305-0047, Japan.
authors.forename: Oscar
authors.identifier: 000000017931603X
authors.initials: O
authors.lastname: Custance