title: Atomic resolution imaging and spectroscopy of barium atoms and functional groups on graphene oxide.
abstract: We present an atomic resolution transmission electron microscopy (TEM) and scanning TEM (STEM) study of the local structure and composition of graphene oxide modified with Ba(2+). In our experiments, which are carried out at 80kV, the acquisition of contamination-free high-resolution STEM images is only possible while heating the sample above 400°C using a highly stable heating holder. Ba atoms are identified spectroscopically in electron energy-loss spectrum images taken at 800°C and are associated with bright contrast in high-angle annular dark-field STEM images. The spectrum images also show that Ca and O occur together and that Ba is not associated with a significant concentration of O. The electron dose used for spectrum imaging results in beam damage to the specimen, even at elevated temperature. It is also possible to identify Ba atoms in high-resolution TEM images acquired using shorter exposure times at room temperature, thereby allowing the structure of graphene oxide to be studied using complementary TEM and STEM techniques over a wide range of temperatures.
authors.affiliation: Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, D-52425 Jülich, Germany. Electronic address: ChrisBoothroyd@cantab.net.
authors.forename: C B
authors.initials: CB
authors.lastname: Boothroyd
authors.affiliation: Centro Atómico Bariloche, 8400 - San Carlos de Bariloche, Argentina.
authors.forename: M S
authors.initials: MS
authors.lastname: Moreno
authors.affiliation: Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, D-52425 Jülich, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Duchamp
authors.affiliation: Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, D-52425 Jülich, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Kovács
authors.affiliation: Department of Chemistry, Universidad Nacional de Río Cuarto, X5804BYA Río Cuarto, Argentina.
authors.forename: N
authors.initials: N
authors.lastname: Monge
authors.affiliation: Department of Chemistry, Universidad Nacional de Río Cuarto, X5804BYA Río Cuarto, Argentina.
authors.forename: G M
authors.initials: GM
authors.lastname: Morales
authors.affiliation: Department of Chemistry, Universidad Nacional de Río Cuarto, X5804BYA Río Cuarto, Argentina.
authors.forename: C A
authors.initials: CA
authors.lastname: Barbero
authors.affiliation: Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, D-52425 Jülich, Germany.
authors.forename: R E
authors.initials: RE
authors.lastname: Dunin-Borkowski
keywords: Atomic resolution; Functional groups; Graphene oxide; Scanning transmission electron microscopy; Single atom imaging; Spectrum imaging; Transmission electron microscopy