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  1. Article ; Online: Scanning transmission helium ion microscopy on carbon nanomembranes

    Daniel Emmrich / Annalena Wolff / Nikolaus Meyerbröker / Jörg K. N. Lindner / André Beyer / Armin Gölzhäuser

    Beilstein Journal of Nanotechnology, Vol 12, Iss 1, Pp 222-

    2021  Volume 231

    Abstract: A dark-field scanning transmission ion microscopy detector was designed for the helium ion microscope. The detection principle is based on a secondary electron conversion holder with an exchangeable aperture strip allowing its acceptance angle to be ... ...

    Abstract A dark-field scanning transmission ion microscopy detector was designed for the helium ion microscope. The detection principle is based on a secondary electron conversion holder with an exchangeable aperture strip allowing its acceptance angle to be tuned from 3 to 98 mrad. The contrast mechanism and performance were investigated using freestanding nanometer-thin carbon membranes. The results demonstrate that the detector can be optimized either for most efficient signal collection or for maximum image contrast. The designed setup allows for the imaging of thin low-density materials that otherwise provide little signal or contrast and for a clear end-point detection in the fabrication of nanopores. In addition, the detector is able to determine the thickness of membranes with sub-nanometer precision by quantitatively evaluating the image signal and comparing the results with Monte Carlo simulations. The thickness determined by the dark-field transmission detector is compared to X-ray photoelectron spectroscopy and energy-filtered transmission electron microscopy measurements.
    Keywords carbon nanomembranes ; dark field ; helium ion microscopy (him) ; scanning transmission ion microscopy (stim) ; srim simulations ; Technology ; T ; Chemical technology ; TP1-1185 ; Science ; Q ; Physics ; QC1-999
    Subject code 530
    Language English
    Publishing date 2021-02-01T00:00:00Z
    Publisher Beilstein-Institut
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article ; Online: Characterisation of the PS-PMMA Interfaces in Microphase Separated Block Copolymer Thin Films by Analytical (S)TEM

    Julius Bürger / Vinay S. Kunnathully / Daniel Kool / Jörg K. N. Lindner / Katharina Brassat

    Nanomaterials, Vol 10, Iss 1, p

    2020  Volume 141

    Abstract: Block copolymer (BCP) self-assembly is a promising tool for next generation lithography as microphase separated polymer domains in thin films can act as templates for surface nanopatterning with sub-20 nm features. The replicated patterns can, however, ... ...

    Abstract Block copolymer (BCP) self-assembly is a promising tool for next generation lithography as microphase separated polymer domains in thin films can act as templates for surface nanopatterning with sub-20 nm features. The replicated patterns can, however, only be as precise as their templates. Thus, the investigation of the morphology of polymer domains is of great importance. Commonly used analytical techniques (neutron scattering, scanning force microscopy) either lack spatial information or nanoscale resolution. Using advanced analytical (scanning) transmission electron microscopy ((S)TEM), we provide real space information on polymer domain morphology and interfaces between polystyrene (PS) and polymethylmethacrylate (PMMA) in cylinder- and lamellae-forming BCPs at highest resolution. This allows us to correlate the internal structure of polymer domains with line edge roughnesses, interface widths and domain sizes. STEM is employed for high-resolution imaging, electron energy loss spectroscopy and energy filtered TEM (EFTEM) spectroscopic imaging for material identification and EFTEM thickness mapping for visualisation of material densities at defects. The volume fraction of non-phase separated polymer species can be analysed by EFTEM. These methods give new insights into the morphology of polymer domains the exact knowledge of which will allow to improve pattern quality for nanolithography.
    Keywords block copolymers ; self-assembly ; polymer interface ; nanostructure metrology ; line edge roughness ler ; (s)tem ; stem-eels of ps and pmma ; Chemistry ; QD1-999
    Subject code 669
    Language English
    Publishing date 2020-01-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  3. Article ; Online: Quality or Quantity? How Structural Parameters Affect Catalytic Activity of Iron Oxides for CO Oxidation

    Steffen Schlicher / Nils Prinz / Julius Bürger / Andreas Omlor / Christian Singer / Mirijam Zobel / Roland Schoch / Jörg K. N. Lindner / Volker Schünemann / Sven Kureti / Matthias Bauer

    Catalysts, Vol 12, Iss 675, p

    2022  Volume 675

    Abstract: The replacement of noble metal catalysts by abundant iron as an active compound in CO oxidation is of ecologic and economic interest. However, improvement of their catalytic performance to the same level as state-of-the-art noble metal catalysts requires ...

    Abstract The replacement of noble metal catalysts by abundant iron as an active compound in CO oxidation is of ecologic and economic interest. However, improvement of their catalytic performance to the same level as state-of-the-art noble metal catalysts requires an in depth understanding of their working principle on an atomic level. As a contribution to this aim, a series of iron oxide catalysts with varying Fe loadings from 1 to 20 wt% immobilized on a γ-Al 2 O 3 support is presented here, and a multidimensional structure–activity correlation is established. The CO oxidation activity is correlated to structural details obtained by various spectroscopic, diffraction, and microscopic methods, such as PXRD, PDF analysis, DRUVS, Mössbauer spectroscopy, STEM-EDX, and XAS. Low Fe loadings lead to less agglomerated but high percentual amounts of isolated, tetrahedrally coordinated iron oxide species, while the absolute amount of isolated species reaches its maximum at high Fe loadings. Consequently, the highest CO oxidation activity in terms of turnover frequencies can be correlated to small, finely dispersed iron oxide species with a large amount of tetrahedrally oxygen coordinated iron sites, while the overall amount of isolated iron oxide species correlates with a lower light-off temperature.
    Keywords CO oxidation ; iron oxide ; emission control ; PDF ; STEM-EDX mapping ; XAS ; Chemical technology ; TP1-1185 ; Chemistry ; QD1-999
    Subject code 540
    Language English
    Publishing date 2022-06-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  4. Article: Easily Accessible Protein Nanostructures via Enzyme Mediated Addressing

    Rüdiger, Arne A / Jörg K. N. Lindner / Katharina Brassat / Oliver I. Strube / Wolfgang Bremser

    Langmuir. 2018 Mar. 26, v. 34, no. 14

    2018  

    Abstract: Site-specific formation of nanoscaled protein structures is a challenging task. Most known structuring methods are either complex and hardly upscalable or do not apply to biological matter at all. The presented combination of enzyme mediated ... ...

    Abstract Site-specific formation of nanoscaled protein structures is a challenging task. Most known structuring methods are either complex and hardly upscalable or do not apply to biological matter at all. The presented combination of enzyme mediated autodeposition and nanosphere lithography provides an easy-to-apply approach for the buildup of protein nanostructures over a large scale. The key factor is the tethering of enzyme to the support in designated areas. Those areas are provided via prepatterning of enzymatically active antidots with variable diameters. Enzymatically triggered protein addressing occurs exclusively at the intended areas and continues until the entire active area is coated. After this, the reaction self-terminates. The major advantage of the presented method lies in its easy applicability and upscalability. Large-area structuring of entire support surfaces with features on the nanometer scale is performed efficiently and without the necessity of harsh conditions. These are valuable premises for large-scale applications with potentials in biosensor technology, nanoelectronics, and life sciences.
    Keywords biosensors ; nanospheres ; protein structure
    Language English
    Dates of publication 2018-0326
    Size p. 4264-4270.
    Publishing place American Chemical Society
    Document type Article
    ZDB-ID 2005937-1
    ISSN 1520-5827 ; 0743-7463
    ISSN (online) 1520-5827
    ISSN 0743-7463
    DOI 10.1021/acs.langmuir.7b04089
    Database NAL-Catalogue (AGRICOLA)

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  5. Article ; Online: A Novel Lubricant Based on Covalent Functionalized Graphene Oxide Quantum Dots

    Andreas Wolk / Marta Rosenthal / Stephan Neuhaus / Klaus Huber / Katharina Brassat / Jörg K. N. Lindner / Richard Grothe / Guido Grundmeier / Wolfgang Bremser / René Wilhelm

    Scientific Reports, Vol 8, Iss 1, Pp 1-

    2018  Volume 9

    Abstract: Abstract Dodecyl amine edge functionalized few-layer graphene oxide quantum dots were synthesized in good yields. The covalent functionalization was demonstrated with NMR and AFM-IR. The resulting structure and particle size was measured with AFM and ... ...

    Abstract Abstract Dodecyl amine edge functionalized few-layer graphene oxide quantum dots were synthesized in good yields. The covalent functionalization was demonstrated with NMR and AFM-IR. The resulting structure and particle size was measured with AFM and HRTEM. The thermal stability of the compound was investigated and showed a stability of up to 220 °C. The modified graphene oxide quantum dots showed excellent solubility in various organic solvents, including ethers, methanol, toluene, n-hexane, heptane, xylene, dichloromethane and toluene. The stability of a resulting toluene solution was also proven by static light scattering measurements over several days. The excellent solubility gives the possibility of an efficient and fast spray application of the functionalized graphene oxide quantum dots to steel surfaces. Hence, the macroscopic friction behavior was investigated with a Thwing-Albert FP-2250 friction tester. A thin film of the dodecyl amine functionalized graphene oxide quantum dots on steel lowered the friction coefficient from 0.17 to 0.11 and revealed a significant corrosion inhibition effect.
    Keywords Medicine ; R ; Science ; Q
    Subject code 540
    Language English
    Publishing date 2018-04-01T00:00:00Z
    Publisher Nature Publishing Group
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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