March 28, 1994 - March 28, 2027

  • Date:22TuesdayJanuary 2019

    Understanding properties of advanced low-dimensional materials by low-voltage atomic-scale TEM experiments

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    Time
    11:00 - 12:00
    Location
    Perlman Chemical Sciences Building
    Room 404
    Lecturer
    Prof. Ute Kaiser
    Central Facility Materials Science Electron Microscopy, Ulm University, Ulm
    Organizer
    Department of Molecular Chemistry and Materials Science
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    AbstractShow full text abstract about A new type of transmission electron microscopes operating at...»
    A new type of transmission electron microscopes operating at electron energies between 80keV and 20keV has been developed to obtain structural and electronic properties of advanced low-dimensional material at the atomic scale. It allows to undercut most of the materials knock-on damage thresholds and enables sub-Angstroem resolution in an 4000x4000 pixels, single-shoot image down to 40keV by correcting not only the geometrical aberrations of the objective lens but also its chromatic aberration. During the imaging process, the interaction of the beam electrons with the low-dimensional material can, nevertheless, results in changes of the atomic structure due to ionization and radiolysis, and sophisticated sample preparation methods are employed to reduce these effects. In this talk, we briefly outline key instrumental and methodological developments and report on structural properties of low-dimensional materials. We not only determine the structure of the pristine material but also use the electron beam to engineer defined properties. Thus, we show for instance the dynamics of extended defects in MoTe2 and WS2 and the creation of a commensurate charge density wave (CDW) in a monolayer 1T-TaSe2, as well as properties of MnPS3, and moreover the dynamics and bond order changing of dirhenium molecule in single-walled carbon nanotubes. Finally we intercalate bilayer graphene by lithium and study in-situ lithiation and delithiation between bilayer graphene, identify single Li atoms as well as the structure of the new high density crystalline Li- phase.
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