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https://www.readbyqxmd.com/read/29340607/collection-efficiency-and-acceptance-maps-of-electron-detectors-for-understanding-signal-detection-on-modern-scanning-electron-microscopy
#1
Toshihide Agemura, Takashi Sekiguchi
Collection efficiency and acceptance maps of typical detectors in modern scanning electron microscopes (SEMs) were investigated. Secondary and backscattered electron trajectories from a specimen to through-the-lens and under-the-lens detectors placed on an electron optical axis and an Everhart-Thornley detector mounted on a specimen chamber were simulated three-dimensionally. The acceptance maps were drawn as the relationship between the energy and angle of collected electrons under different working distances...
January 11, 2018: Microscopy
https://www.readbyqxmd.com/read/29340604/transient-recruitment-of-m-ras-gtpase-to-phagocytic-cups-in-raw264-macrophages-during-fc%C3%AE-r-mediated-phagocytosis
#2
Youhei Egami, Nobukazu Araki
M-Ras, a member of the Ras superfamily, is known to be involved in diverse cellular processes. However, its involvement in FcγR-mediated phagocytosis remains unknown. We examined the spatiotemporal localization of M-Ras during the engulfment of IgG-opsonized erythrocytes (IgG-Es) in RAW264 macrophages. By the live-cell imaging of fluorescent protein-fused M-Ras, we found that M-Ras was localized to the membrane of phagocytic cups during the early stage of phagosome formation. Notably, ratiometric image analysis revealed that M-Ras was concentrated in the membrane of forming phagosomes...
January 11, 2018: Microscopy
https://www.readbyqxmd.com/read/29340597/managing-dose-damage-and-data-rates-in-multi-frame-spectrum-imaging
#3
Lewys Jones, Aakash Varambhia, Richard Beanland, Demie Kepaptsoglou, Ian Griffiths, Akimitsu Ishizuka, Feridoon Azough, Robert Freer, Kazuo Ishizuka, David Cherns, Quentin M Ramasse, Sergio Lozano-Perez, Peter D Nellist
As an instrument, the scanning transmission electron microscope is unique in being able to simultaneously explore both local structural and chemical variations in materials at the atomic scale. This is made possible as both types of data are acquired serially, originating simultaneously from sample interactions with a sharply focused electron probe. Unfortunately, such scanned data can be distorted by environmental factors, though recently fast-scanned multi-frame imaging approaches have been shown to mitigate these effects...
January 11, 2018: Microscopy
https://www.readbyqxmd.com/read/29325131/crystal-structures-of-high-pressure-phases-formed-in-si-by-laser-irradiation
#4
Hiroyuki Iwata, Daisuke Kawaguchi, Hiroyasu Saka
Internal modification induced in Si by a permeable pulse laser was investigated by transmission electron microscopy. A laser induced modified volume (LIMV) was a cylindrical rod along the track of a laser beam with the head at the focus of the laser beam. In the LIMV, beside voids, dislocations, micro-cracks and what had been supposed to be an unidentified high-pressure phase (hpp) of Si were observed in LIMV. The so-called 'hpp' was identified mostly as diamond Si.
January 6, 2018: Microscopy
https://www.readbyqxmd.com/read/29315401/development-of-a-real-time-wave-field-reconstruction-tem-system-ii-correction-of-coma-aberration-and-3-fold-astigmatism-and-real-time-correction-of-2-fold-astigmatism
#5
Takahiro Tamura, Yoshihide Kimura, Yoshizo Takai
In this study, a function for the correction of coma aberration, 3-fold astigmatism and real-time correction of 2-fold astigmatism was newly incorporated into a recently developed real-time wave field reconstruction TEM system. The aberration correction function was developed by modifying the image-processing software previously designed for auto focus tracking, as described in the first article of this series. Using the newly developed system, the coma aberration and 3-fold astigmatism were corrected using the aberration coefficients obtained experimentally before the processing was carried out...
January 5, 2018: Microscopy
https://www.readbyqxmd.com/read/29309606/attainment-of-40-5-pm-spatial-resolution-using-300-kv-scanning-transmission-electron-microscope-equipped-with-fifth-order-aberration-corrector
#6
Shigeyuki Morishita, Ryo Ishikawa, Yuji Kohno, Hidetaka Sawada, Naoya Shibata, Yuichi Ikuhara
The achievement of a fine electron probe for high-resolution imaging in scanning transmission electron microscopy requires technological developments, especially in electron optics. For this purpose, we developed a microscope with a fifth-order aberration corrector that operates at 300 kV. The contrast flat region in an experimental Ronchigram, which indicates the aberration-free angle, was expanded to 70 mrad. By using a probe with convergence angle of 40 mrad in the scanning transmission electron microscope at 300 kV, we attained the spatial resolution of 40...
December 22, 2017: Microscopy
https://www.readbyqxmd.com/read/29253238/two-dimensional-gaussian-fitting-for-precise-measurement-of-lattice-constant-deviation-from-a-selected-area-diffraction-map
#7
Raman Bekarevich, Kazutaka Mitsuishi, Tsuyoshi Ohnishi, Fumihiko Uesugi, Masaki Takeguchi, Yoshiyuki Inaguma, Takahisa Ohno, Kazunori Takada
Unlike X-ray diffraction or Raman techniques, which suffer from low spatial resolution, transmission electron microscopy can be used to obtain strain maps of nanoscaled materials and devices. Convergent-beam electron diffraction (CBED) and nanobeam electron diffraction (NBED) techniques detect the deviation of a lattice constant (i.e. an indicator of strain) within 0.01%; however, their use is restricted to beam-insensitive samples. Selected-area electron diffraction (SAED) does not have such limitations but has low spatial resolution and precision...
December 15, 2017: Microscopy
https://www.readbyqxmd.com/read/29228240/contrast-of-positively-charged-oxide-precipitate-in-out-lens-in-lens-and-in-column-se-image
#8
Šárka Mikmeková, Haruo Nakamichi, Masayasu Nagoshi
Modern scanning electron microscopes are usually equipped with multiple detectors and enable simultaneous collection of two or even three secondary electron images. The secondary electrons become divided between the detectors in dependence on their initial kinetic energy and emission angle. In this study, sharing of the secondary electrons by out-lens, in-lens and in-column detectors has been systematically investigated. Energy filtering of the signal electrons is demonstrated by separation of the voltage and the topographical contrast in the micrographs obtained by out-lens and in-lens/in-column detectors...
December 8, 2017: Microscopy
https://www.readbyqxmd.com/read/29190375/high-resolution-mapping-of-molecules-in-an-ionic-liquid-via-scanning-transmission-electron-microscopy
#9
Tomohiro Miyata, Teruyasu Mizoguchi
Understanding structures and spatial distributions of molecules in liquid phases is crucial for the control of liquid properties and to develop efficient liquid-phase processes. Here, real-space mapping of molecular distributions in a liquid was performed. Specifically, the ionic liquid 1-Ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (C2mimTFSI) was imaged using atomic-resolution scanning transmission electron microscopy. Simulations revealed network-like bright regions in the images that were attributed to the TFSI- anion, with minimal contributions from the C2mim+ cation...
November 28, 2017: Microscopy
https://www.readbyqxmd.com/read/29186480/gold-nanoparticle-printed-coverslips-to-facilitate-fluorescence-tem-correlative-microscopy
#10
Neeraj Prabhakar, Anni Määttänen, Jouko Peltonen, Pekka Hänninen, Markus Peurla, Jessica M Rosenholm
Correlative light and electron microscopy (CLEM) allows combining the advantages of fluorescence microscopy and electron microscopy for cell imaging. Rare phenomenon expressing cells can be studied by specifically tagged fluorophores with fluorescence microscopy. Subsequently, cells can be fixed and ultra-structural details can be studied with transmission electron microscopy (TEM) at a higher resolution. However, precise landmarks are necessary to track the same cell throughout the CLEM process. In this technical report, we present a high contrast inkjet-printed gold nanoparticle patterns over commercial glass coverslip to facilitate cell tracking with correlative microscopy...
November 23, 2017: Microscopy
https://www.readbyqxmd.com/read/29140449/a-quantum-mechanical-exploration-of-phonon-energy-loss-spectroscopy-using-electrons-in-the-aloof-beam-geometry
#11
L J Allen, H G Brown, S D Findlay, B D Forbes
Phonon energy-loss spectroscopy using electrons has both high resolution and low resolution components, associated with short- and long-range interactions, respectively. In this paper, we discuss how these two contributions arise from a fundamental quantum mechanical perspective. Starting from a correlated model for the atomic motion we show how short range 'impact' scattering and long range 'dipole' scattering arises. The latter dominates in aloof beam imaging, an imaging geometry in which radiation damage can be avoided...
November 13, 2017: Microscopy
https://www.readbyqxmd.com/read/29140445/precise-method-for-measuring-spatial-coherence-in-tem-beams-using-airy-diffraction-patterns
#12
Jun Yamasaki, Yuki Shimaoka, Hirokazu Sasaki
We have developed a method to precisely measure spatial coherence in electron beams. The method does not require an electron biprism and can be implemented in existing analytical transmission electron microscopes equipped with a post-column energy filter. By fitting the Airy diffraction pattern of the selector aperture, various parameters such as geometric aberrations of the lens system and the point-spread function of the diffraction blurring are precisely determined. From the measurements of various beam diameters, components that are attributed to the partial spatial coherence are successfully separated from the point-spread functions...
November 13, 2017: Microscopy
https://www.readbyqxmd.com/read/29136225/evaluation-of-eels-spectrum-imaging-data-by-spectral-components-and-factors-from-multivariate-analysis
#13
Siyuan Zhang, Christina Scheu
Multivariate analysis is a powerful tool to process spectrum imaging datasets of electron energy loss spectroscopy. Most spatial variance of the datasets can be explained by a limited numbers of components. We explore such dimension reduction to facilitate quantitative analyses of spectrum imaging data, supervising the spectral components instead of spectra at individual pixels. In this study, we use non-negative matrix factorization to decompose datasets from Fe2O3 thin films with different Sn doping profiles on SnO2 and Si substrates...
November 9, 2017: Microscopy
https://www.readbyqxmd.com/read/29136206/calculation-consequences-and-measurement-of-the-point-spread-function-for-low-loss-inelastic-scattering
#14
R F Egerton
We have previously derived an analytical formula for the point spread function (PSF) that describes the delocalization of low-loss inelastic scattering. Here, we modify the formula to take account variation of scattered-electron phase. The exponentially attenuated Lorentzian form is retained but its halfwidth at half maximum is chosen to provide better agreement with measurements of the median delocalization distance. For low energy losses, the 1/r2 tails of the PSF extend beyond the region of energy deposition, allowing a small-diameter electron probe to provide energy-loss data from relatively undamaged regions of a beam-sensitive specimen...
November 9, 2017: Microscopy
https://www.readbyqxmd.com/read/29136197/mapping-vis-terahertz-%C3%A2-17-thz-surface-plasmons-sustained-on-native-and-chemically-functionalized-percolated-gold-thin-films-using-eels
#15
Patricia Abellan, Patrick Z El-Khoury, Quentin M Ramasse
Heterogeneous assemblies of molecules (Rhodamine B) adsorbed onto a nano-corrugated metallic surface (a percolated Au network) are investigated using electron energy loss spectroscopy in the scanning transmission electron microscope (STEM-EELS). Our first measurements target the native metallic substrate, which consists of a commercial Au thin film atop an ultrathin carbon membrane. The Au film displays a percolated morphology with nanostructures of estimated thickness ≤10 nm approximately. We observe a rich plasmonic response from the metallic substrate; one which varies nanometrically and spans the VIS-terahertz region...
November 9, 2017: Microscopy
https://www.readbyqxmd.com/read/29136165/low-dose-electron-energy-loss-spectroscopy-using-electron-counting-direct-detectors
#16
Alan Maigné, Matthias Wolf
Since the development of parallel electron energy loss spectroscopy (EELS), charge-coupled devices (CCDs) have been the default detectors for EELS. With the recent development of electron-counting direct-detection cameras, micrographs can be acquired under very low electron doses at significantly improved signal-to-noise ratio. In spectroscopy, in particular in combination with a monochromator, the signal can be extremely weak and the detection limit is principally defined by noise introduced by the detector...
November 9, 2017: Microscopy
https://www.readbyqxmd.com/read/29016924/basics-and-applications-of-elnes-calculations
#17
Hidekazu Ikeno, Teruyasu Mizoguchi
The electron energy loss near edge structures (ELNES) appearing in an electron energy loss spectrum obtained through transmission electron microscopy (TEM) have the potential to unravel atomic and electronic structures with sub-nano meter resolution. For this reason, TEM-ELNES has become one of the most powerful analytical methods in materials research. On the other hand, theoretical calculations are indispensable in interpreting the ELNES spectrum. Here, the basics and applications of one-particle, two-particle and multi-particle ELNES calculations are reviewed...
October 1, 2017: Microscopy
https://www.readbyqxmd.com/read/29016923/surface-morphology-and-dislocation-characteristics-near-the-surface-of-4h-sic-wafer-using-multi-directional-scanning-transmission-electron-microscopy
#18
Takahiro Sato, Yoshihisa Orai, Yuya Suzuki, Hiroyuki Ito, Toshiyuki Isshiki, Munetoshi Fukui, Kuniyasu Nakamura, C T Schamp
To improve the reliability of silicon carbide (SiC) electronic power devices, the characteristics of various kinds of crystal defects should be precisely understood. Of particular importance is understanding the correlation between the surface morphology and the near surface dislocations. In order to analyze the dislocations near the surface of 4H-SiC wafers, a dislocation analysis protocol has been developed. This protocol consists of the following process: (1) inspection of surface defects using low energy scanning electron microscopy (LESEM), (2) identification of small and shallow etch pits using KOH low temperature etching, (3) classification of etch pits using LESEM, (4) specimen preparation of several hundred nanometer thick sample using the in-situ focused ion beam micro-sampling® technique, (5) crystallographic analysis using the selected diffraction mode of the scanning transmission electron microscope (STEM), and (6) determination of the Burgers vector using multi-directional STEM (MD-STEM)...
October 1, 2017: Microscopy
https://www.readbyqxmd.com/read/29016922/morphologic-mechanisms-of-increased-vascular-permeability-of-triolein-emulsion-to-the-blood-brain-barrier
#19
Yuri Sol, Seon Hee Choi, Hak Jin Kim, Yong-Woo Kim, Byung Mann Cho, Hyung Soo Han, Ki J Choi
Triolein emulsion has been known to increase vascular permeability in the brain when it is infused into the carotid artery. The purpose of this study was to identify the morphologic mechanism of increased vascular permeability in brain induced by infusion of emulsified triolein into the carotid artery by transmission electron microscopy (TEM). Triolein emulsion was infused into the carotid artery of rats. TEM using lanthanum tracer was used to evaluate morphologic changes in endothelium with a focus on transcytotic vesicles and tight junction opening...
October 1, 2017: Microscopy
https://www.readbyqxmd.com/read/29016921/atomic-and-nanoscale-imaging-of-a-cellulose-nanofiber-and-pd-nanoparticles-composite-using-lower-voltage-high-resolution-tem
#20
Megumi Ohwada, Yoshiteru Mizukoshi, Tomoko Shimokawa, Noriko Hayashi, Yuichiro Hayasaka, Toyohiko J Konno
We have examined the advanced application of transmission electron microscopy (TEM) for the structural characterization of a composite of cellulose nanofiber (CNF) and palladium (Pd) nanoparticles. In the present study, we focused on electron-irradiation damage and optimization of high-resolution TEM imaging of the composite. The investigation indicates that the CNF breaks even under low-electron-dose conditions at an acceleration voltage of 200 kV. We then applied lower-voltage TEM at 60 kV using a spherical aberration corrector and a monochromator, in order to reduce electron-irradiation damage and improve the spatial resolution...
October 1, 2017: Microscopy
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