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Ultramicroscopy

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https://www.readbyqxmd.com/read/29324400/determination-of-atomic-positions-from-time-resolved-high-resolution-transmission-electron-microscopy-images
#1
Zahra Hussaini, Pin Ann Lin, Bharath Natarajan, Wenhui Zhu, Renu Sharma
For many reaction processes, such as catalysis, phase transformations, nanomaterial synthesis etc., nanoscale observations at high spatial (sub-nanometer) and temporal (millisecond) resolution are required to characterize and comprehend the underlying factors that favor one reaction over another. The combination of such spatial and temporal resolution (up to 600 µs), while rich in information, produces a large number of snapshots, each of which must be analyzed to obtain the structural (and thereby chemical) information...
December 28, 2017: Ultramicroscopy
https://www.readbyqxmd.com/read/29306810/development-of-a-high-brightness-ultrafast-transmission-electron-microscope-based-on-a-laser-driven-cold-field-emission-source
#2
F Houdellier, G M Caruso, S Weber, M Kociak, A Arbouet
We report on the development of an ultrafast Transmission Electron Microscope based on a cold field emission source which can operate in either DC or ultrafast mode. Electron emission from a tungsten nanotip is triggered by femtosecond laser pulses which are tightly focused by optical components integrated inside a cold field emission source close to the cathode. The properties of the electron probe (brightness, angular current density, stability) are quantitatively determined. The measured brightness is the largest reported so far for UTEMs...
December 27, 2017: Ultramicroscopy
https://www.readbyqxmd.com/read/29291437/an-efficient-approach-to-integrated-mev-ion-imaging
#3
T Nikbakht, O Kakuee, V A Solé, Y Vosuoghi, M Lamehi-Rachti
An ionoluminescence (IL) spectral imaging system, besides the common MeV ion imaging facilities such as µ-PIXE and µ-RBS, is implemented at the Van de Graaff laboratory of Tehran. A versatile processing software is required to handle the large amount of data concurrently collected in µ-IL and common MeV ion imaging measurements through the respective methodologies. The open-source freeware PyMca, with image processing and multivariate analysis capabilities, is employed to simultaneously process common MeV ion imaging and µ-IL data...
December 24, 2017: Ultramicroscopy
https://www.readbyqxmd.com/read/29287250/analyzing-the-channel-dopant-profile-in-next-generation-finfets-via-atom-probe-tomography
#4
Andrew J Martin, Yong Wei, Andreas Scholze
Dopant analysis in next-generation semiconductor devices has become increasingly difficult for traditionally used analytical techniques. Atom probe tomography has been viewed by some as a possible solution to these challenges because of its three-dimensional capabilities, forcing the atom probe to mature at a rapid pace in this particular field. This work presents a well-rounded analysis of how APT can be used to examine B dopant diffusion into the channel of a next-generation FinFET, where the channel dimensions and the number of dopants atoms are significantly smaller than any devices measured by APT to date...
December 20, 2017: Ultramicroscopy
https://www.readbyqxmd.com/read/29274506/spectrum-imaging-of-complex-nanostructures-using-dualeels-ii-absolute-quantification-using-standards
#5
Alan J Craven, Bianca Sala, Joanna Bobynko, Ian MacLaren
Nanometre-sized TixV(1-x)CyNz precipitates in an Fe20%Mn steel matrix with a thickness range from 14 to 40 nm are analysed using DualEELS. Their thicknesses, volumes and compositions are quantified using experimental binary standards and the process used to give robust results is described. Precisions of a few percent are achieved with accuracies that are estimated to be of a similar magnitude. Sensitivities are shown to be at 0.5-1 unit cells range in the thinnest matrix region, based on the assumption that a sub-lattice is fully populated by the element...
December 13, 2017: Ultramicroscopy
https://www.readbyqxmd.com/read/29268136/fine-tuning-an-aberration-corrected-adf-stem
#6
Earl J Kirkland
Aberration correctors offer greatly enhanced resolution in electron microscopes, however can require dramatically more complicated adjustments. A method of computer adjustment of a probe forming aberration corrector in a Scanning Transmission Electron Microscope (STEM) is proposed and analyzed using image simulation. This method works directly with the image and should work well with crystalline specimens. It does not have a significant dependence on post specimen lens aberrations.
December 12, 2017: Ultramicroscopy
https://www.readbyqxmd.com/read/29247969/studies-of-x-ray-localization-and-thickness-dependence-in-atomic-scale-elemental-mapping-by-stem-energy-dispersive-x-ray-spectroscopy-using-single-frame-scanning-method
#7
Ping Lu, Jaime M Moya, Renliang Yuan, Jian Min Zuo
The delocalization of x-ray signals limits the spatial resolution in atomic-scale elemental mapping by scanning transmission electron microscopy (STEM) using energy-dispersive x-ray spectroscopy (EDS). In this study, using a SrTiO3 [001] single crystal, we show that the x-ray localization to atomic columns is strongly dependent on crystal thickness, and a thin crystal is critical for improving the spatial resolution in atomic-scale EDS mapping. A single-frame scanning technique is used in this study instead of the multiple-frame technique to avoid peak broadening due to tracking error...
December 8, 2017: Ultramicroscopy
https://www.readbyqxmd.com/read/29277084/sampling-limits-for-electron-tomography-with-sparsity-exploiting-reconstructions
#8
Yi Jiang, Elliot Padgett, Robert Hovden, David A Muller
Electron tomography (ET) has become a standard technique for 3D characterization of materials at the nano-scale. Traditional reconstruction algorithms such as weighted back projection suffer from disruptive artifacts with insufficient projections. Popularized by compressed sensing, sparsity-exploiting algorithms have been applied to experimental ET data and show promise for improving reconstruction quality or reducing the total beam dose applied to a specimen. Nevertheless, theoretical bounds for these methods have been less explored in the context of ET applications...
December 7, 2017: Ultramicroscopy
https://www.readbyqxmd.com/read/29248871/selective-production-of-hydrogen-ion-species-at-atomically-designed-nanotips
#9
Hironori Moritani, Radovan Urban, Kyle Nova, Mark Salomons, Robert Wolkow, Jason Pitters
Hydrogen scanning ion microscopy systems rely on nanotip gas field ion sources to generate the hydrogen ion beam. The exact structure of the nanotip and the applied electric field are shown to be important. It is demonstrated that hydrogen ion beams are found to occur as mixtures of H+, H2+ and H3+ depending on the electric field strength and the nanotip structure. Various nanotips were prepared, including single atom tips (SATs), trimers and other nano-structured tips to compare the contents of hydrogen ion beams...
December 7, 2017: Ultramicroscopy
https://www.readbyqxmd.com/read/29248870/preventing-damage-and-redeposition-during-focused-ion-beam-milling-the-umbrella-method
#10
T Vermeij, E Plancher, C C Tasan
Focused ion beam (FIB) milling has enabled the development of key microstructure characterization techniques (e.g. 3D electron backscatter diffraction (EBSD), 3D scanning electron microscopy imaging, site-specific sample preparation for transmission electron microscopy, site-specific atom probe tomography), and micro-mechanical testing techniques (e.g. micro-pillar compression, micro-beam bending, in-situ TEM nanoindentation). Yet, in most milling conditions, some degree of FIB damage is introduced via material redeposition, Ga+ ion implantation or another mechanism...
December 7, 2017: Ultramicroscopy
https://www.readbyqxmd.com/read/29245031/nanometer-precise-optical-length-measurement-using-near-field-scanning-optical-microscopy-with-sharpened-single-carbon-nanotube-probe
#11
Takehiro Tachizaki, Toshihiko Nakata, Kaifeng Zhang, Ichiro Yamakawa, Shin-Ichi Taniguchi
We have developed and characterized a plasmon-excitation scattering-type near-field scanning optical microscope with sharpened single carbon nanotube probe. The developed microscope can optically capture differences in the refractive index of single-nanometer surface structures. Statistical analysis enabled us to estimate the precision of the optical length measurement to 1.8 nm.
December 7, 2017: Ultramicroscopy
https://www.readbyqxmd.com/read/29241145/wet-chemical-etching-of-atom-probe-tips-for-artefact-free-analyses-of-nanoscaled-semiconductor-structures
#12
D Melkonyan, C Fleischmann, A Veloso, A Franquet, J Bogdanowicz, R J H Morris, W Vandervorst
We introduce an innovative specimen preparation method employing the selectivity of a wet-chemical etching step to improve data quality and success rates in the atom probe analysis of contemporary semiconductor devices. Firstly, on the example of an SiGe fin embedded in SiO2 we demonstrate how the selective removal of SiO2 from the final APT specimen significantly improves accuracy and reliability of the reconstructed data. With the oxide removal, we eliminate the origin of shape artefacts, i.e. the formation of a non-hemispherical tip shape, that are typically observed in the reconstructed volume of complex systems...
December 7, 2017: Ultramicroscopy
https://www.readbyqxmd.com/read/29268135/transmission-scanning-electron-microscopy-defect-observations-and-image-simulations
#13
Patrick G Callahan, Jean-Charles Stinville, Eric R Yao, McLean P Echlin, Michael S Titus, Marc De Graef, Daniel S Gianola, Tresa M Pollock
The new capabilities of a FEG scanning electron microscope (SEM) equipped with a scanning transmission electron microscopy (STEM) detector for defect characterization have been studied in parallel with transmission electron microscopy (TEM) imaging. Stacking faults and dislocations have been characterized in strontium titanate, a polycrystalline nickel-base superalloy and a single crystal cobalt-base material. Imaging modes that are similar to conventional TEM (CTEM) bright field (BF) and dark field (DF) and STEM are explored, and some of the differences due to the different accelerating voltages highlighted...
December 6, 2017: Ultramicroscopy
https://www.readbyqxmd.com/read/29248869/ion-beam-heating-of-kinetically-constrained-nanomaterials
#14
Xi Cen, Klaus van Benthem
The gallium ion beam heating on electron transparent transmission electron microscopy (TEM) samples of Au/Ni bilayer films supported by SiO2 substrates was studied by in-situ TEM combined with energy dispersive X-ray spectroscopy. Brief Ga+ ion beam irradiation during sample transfer inside the focused ion beam instrument was found to induce dewetting of bilayer films. The observed morphological changes of the metal films are complemented by considerable Au diffusion through the underlying polycrystalline Ni film and adsorption at the Ni/substrate interface...
December 6, 2017: Ultramicroscopy
https://www.readbyqxmd.com/read/29294410/amusement-for-couch-potatoes
#15
P W Hawkes
Recent and not quite so recent books and conference proceedings on electron microscopy and related topics are surveyed. A few books on very different subjects are included to lighten the dough.
December 5, 2017: Ultramicroscopy
https://www.readbyqxmd.com/read/29275175/increasing-compositional-backscattered-electron-contrast-in-scanning-electron-microscopy
#16
F Timischl, N Inoue
A method for increasing compositional or material contrast of a standard semiconductor BSE detector in a scanning electron microscope (SEM) by compensation of the topographic contrast component is proposed. Compensation is based on the physical properties of backscattered electron emission and topography information of the specimen's surface. Three analytical and semi-empirical compensation algorithms employing different physical models and approximations are implemented and compared to conventional BSE signals to show the effectivity of the proposed compensation approach...
December 5, 2017: Ultramicroscopy
https://www.readbyqxmd.com/read/29245032/atomic-force-microscopy-capable-of-vibration-isolation-with-low-stiffness-z-axis-actuation
#17
Shingo Ito, Georg Schitter
For high-resolution imaging without bulky external vibration isolation, this paper presents an atomic force microscope (AFM) capable of vibration isolation with its internal Z-axis (vertical) actuators moving the AFM probe. Lorentz actuators (voice coil actuators) are used for the Z-axis actuation, and flexures guiding the motion are designed to have a low stiffness between the mover and the base. The low stiffness enables a large Z-axis actuation of more than 700 µm and mechanically isolates the probe from floor vibrations at high frequencies...
December 5, 2017: Ultramicroscopy
https://www.readbyqxmd.com/read/29216604/digital-holographic-microscopy-for-3d-surface-characterization-of-polymeric-nanocomposites
#18
Vahid Abbasian, Ehsan A Akhlaghi, Mohammad A Charsooghi, Maasoomeh Bazzar, Ali-Reza Moradi
The aim of this paper is to introduce digital holographic microscopy (DHM) as a non-contact, inexpensive, and non-abrasive method for 3D surface characterization of polymeric nanocomposites. A common-path and vibration-immune Mirau system with a microsphere-assisted arrangement is utilized to increase the lateral resolution of the images. The characterization is performed through the measurement of roughness parameters of the surfaces, which are derived from the recorded holograms. Pure poly(triazole-amide-imide) (PTAI) and PTAI nanocomposite reinforeced with surface modified TiO2 nanoparticles (MN-TiO2) are used and compared...
November 28, 2017: Ultramicroscopy
https://www.readbyqxmd.com/read/29223803/fine-electron-biprism-on-a-si-on-insulator-chip-for-off-axis-electron-holography
#19
Martial Duchamp, Olivier Girard, Giulio Pozzi, Helmut Soltner, Florian Winkler, Rolf Speen, Rafal E Dunin-Borkowski, David Cooper
Off-axis electron holography allows both the amplitude and the phase shift of an electron wavefield propagating through a specimen in a transmission electron microscope to be recovered. The technique requires the use of an electron biprism to deflect an object wave and a reference wave to form an interference pattern. Here, we introduce an approach based on semiconductor processing technology to fabricate fine electron biprisms with rectangular cross-sections. By performing electrostatic calculations and preliminary experiments, we demonstrate that such biprisms promise improved performance for electron holography experiments...
November 22, 2017: Ultramicroscopy
https://www.readbyqxmd.com/read/29182920/effect-of-asymmetric-morphology-on-coupling-surface-plasmon-modes-and-generalized-plasmon-ruler
#20
K J Zhang, B Da, Z J Ding
Plasmon coupling in aggregated noble metal systems can provide a path to manipulate the optical response purposefully and possesses a wide range of application. Previously, most studies focused on the coupling behavior of Ag-Ag dimers with the same shape. However, plasmon coupling between nanoparticles at different morphologies can provide a new way to modulate optical properties due to broken of symmetry. In this work, we investigate systematically the coupling modes of asymmetric Ag-Ag heterodimers consisting of different morphologies by the boundary element method (BEM)...
November 21, 2017: Ultramicroscopy
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