title: Surface determination through atomically resolved secondary-electron imaging.
abstract: Unique determination of the atomic structure of technologically relevant surfaces is often limited by both a need for homogeneous crystals and ambiguity of registration between the surface and bulk. Atomically resolved secondary-electron imaging is extremely sensitive to this registration and is compatible with faceted nanomaterials, but has not been previously utilized for surface structure determination. Here we report a detailed experimental atomic-resolution secondary-electron microscopy analysis of the c(6 × 2) reconstruction on strontium titanate (001) coupled with careful simulation of secondary-electron images, density functional theory calculations and surface monolayer-sensitive aberration-corrected plan-view high-resolution transmission electron microscopy. Our work reveals several unexpected findings, including an amended registry of the surface on the bulk and strontium atoms with unusual seven-fold coordination within a typically high surface coverage of square pyramidal TiO5 units. Dielectric screening is found to play a critical role in attenuating secondary-electron generation processes from valence orbitals.
authors.affiliation: National Center for Electron Microscopy, The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
authors.forename: J
authors.initials: J
authors.lastname: Ciston
authors.affiliation: School of Physics, University of Melbourne, Parkville, Victoria 3010, Australia.
authors.forename: H G
authors.initials: HG
authors.lastname: Brown
authors.affiliation: School of Physics, University of Melbourne, Parkville, Victoria 3010, Australia.
authors.forename: A J
authors.initials: AJ
authors.lastname: D'Alfonso
authors.affiliation: Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, USA.
authors.forename: P
authors.initials: P
authors.lastname: Koirala
authors.affiliation: National Center for Electron Microscopy, The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
authors.forename: C
authors.initials: C
authors.lastname: Ophus
authors.affiliation: Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Lin
authors.affiliation: Application Development Department, Hitachi High Technologies Corp., Ibaraki 312-8504, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Suzuki
authors.affiliation: Advanced Microscope Design Department, Hitachi High Technologies Corp., Ibaraki 312-8504, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Inada
authors.affiliation: Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, New York 11973, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: School of Physics, University of Melbourne, Parkville, Victoria 3010, Australia.
authors.forename: L J
authors.initials: LJ
authors.lastname: Allen
authors.affiliation: Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, USA.
authors.forename: L D
authors.initials: LD
authors.lastname: Marks