23 research outputs found

    4D Scanning Transmission Ultrafast Electron Microscopy: Single-Particle Imaging and Spectroscopy

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    We report the development of 4D scanning transmission ultrafast electron microscopy (ST-UEM). The method was demonstrated in the imaging of silver nanowires and gold nanoparticles. For the wire, the mechanical motion and shape morphological dynamics were imaged, and from the images we obtained the resonance frequency and the dephasing time of the motion. Moreover, we demonstrate here the simultaneous acquisition of dark-field images and electron energy loss spectra from a single gold nanoparticle, which is not possible with conventional methods. The local probing capabilities of ST-UEM open new avenues for probing dynamic processes, from single isolated to embedded nanostructures, without being affected by the heterogeneous processes of ensemble-averaged dynamics. Such methodology promises to have wide-ranging applications in materials science and in single-particle biological imaging

    Electron Energy Loss Spectroscopy Signal Processing Tool for Materials Research

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    Allowing scientists to analyze materials’ structure and chemistry at an atomic level, the electron microscope has become a vital tool in materials engineering. Due to the inherent nature of signals (inelastic electrons or X-ray) having a low signal-to-noise ratio, processing the signal collected with an electron microscope is frequently required and uses sophisticated computer code. The software written to do this can be very difficult to learn and use. To make these tools more easily accessible to new users, we will create a simple user interface and host it online. Using the Rappture development tool, a menu driven graphical user interface was created for the HyperSpy software package allowing all software commands to be handled automatically. Choosing the Rappture development tool means the interface will also be easily updated to include new functionality as HyperSpy evolves. When completed, this interface will be made available online via the NanoHUB server at Purdue University. This will help scientists analyze materials in a uniform and repeatable manner using a readily available and easy to learn interface

    Development of Electron Microscopy Analysis and Simulation tools for nanoHUB

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    Electron microscopy has a crucial role in the field of materials science and structural biology. Although electron microscopy gives lots of important results and findings, some additional simulations and image processing/reconstruction is required to get more information from the data that are collected from the experiments. For this purpose, researchers are using IMOD1 and QSTEM2 for electron microscopy analysis and simulation. IMOD is a set of programs used for tomographic reconstruction and 3D visualization and QSTEM is used for quantitative simulations of TEM and STEM images. However, IMOD and QSTEM are hard to install or use for beginners who are not familiar with computational skills. To overcome this issue, we have developed “Online IMOD and STEM tools” to allow users to perform microscopy analysis and simulation with ease. We applied several ways to launch or combine tools. Based on the original source codes of the software, we used the graphical interface builder Rappture to build a new interface to launch several tools. Also, we used the nanowhim window manager to combine and organize tools. The online version of IMOD and QSTEM will enable researchers from all over the world to use IMOD and QSTEM programs directly and easily on the nanoHUB website

    Introduction of Rare-Earth Oxide Nanoparticles in CNT-Based Nanocomposites for Improved Detection of Underlying CNT Network

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    17 USC 105 interim-entered record; under review.The article of record as published may be found at https://doi.org/10.3390/nano11092168Epoxy resins for adhesive and structural applications are widely employed by various industries. The introduction of high aspect ratio nanometric conductive fillers, i.e., carbon nanotubes, are well studied and are known to improve the electrical properties of the bulk material by orders of magnitude. This improved electrical conductivity has made carbon nanotube-based nanocomposites an attractive material for applications where their weight savings are at a premium. However, the analytical methods for validating carbon nanotube (CNT) nanofiller dispersion and for assuring that the properties they induce extend to the entire volume are destructive and inhibited by poor resolution between matrix and tube bundles. Herein, rare-earth oxide nanoparticles are synthesized on CNT walls for the purpose of increasing the contrast between their network and the surrounding matrix when studied by imaging techniques, alleviating these issues. The adherence of the synthesized nanoparticles to the CNT walls is documented via transmission electron microscopy. The crystalline phases generated during the various fabrication steps are determined using X-ray diffraction. Deep ultraviolet-induced fluorescence of the Eu:Y2 O3 -CNT nanostructures is verified. The impacts to nanocomposite electrical properties resulting from dopant introduction are characterized. The scanning electron microscopy imaging of CNT pulp and nanocomposites fabricated from untreated CNTs and Eu:Y2O3-CNTs are compared, resulting in improved contrast and detection of CNT bundles. The micro-CT scans of composites with similar results are presented for discussion.U.S. Government affiliation is unstated in article text

    Investigation of Nanoparticle Reactions with Laser Heating by In situ

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    Investigation of Polymer Matrix Nano-Aluminum Composites with Pulsed Laser Heating by In-Situ TEM

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    The article of record as published may be found at https://doi.org/10.1002/prep.201900134Nanocomposites of aluminum and fluoropolymers react rapidly due to highly exothermic aluminum fluorination because of the high specific surface area nanoscale particles. In-situ transmission electron microscopy (TEM) techniques are invaluable for real time monitoring of the reactions in these systems at the nanoscale. Here, we investigated the reactions in nanoscale Al (nAl) and THV (terpolymer of tetrafluoroethylene, hexafluoropropylene, and vinylidene fluoride) and nAl-LDPE (low density polyethylene) composites, heated using a pulsed laser in a TEM. Results show that reactions are initiated at about 720 K, when THV starts to decompose, and proceed with the formation and growth of a hollow aluminum fluoride (AlF3) shell. Diffraction patterns revealed that this phase is the rare η-phase AlF3. In contrast, no reactions were observed in the inert nAl-LDPE composites. The experimental and theoretical results reveal that rapid pulsed laser heating and subsequent cooling of a nanoscale sample influences the phases that can form, and can be utilized to investigate other systems.This work was supported by the Young Investigator Program of Department of Defense Office of Naval Research (CBET-1437219)This work was supported by the Young Investigator Program of Department of Defense Office of Naval Research (CBET-1437219

    In Situ

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