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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
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
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
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
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
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
Monalisa Mishra, Ashutosh Choudhury, P Sagar Achary, Harekrushna Sahoo
Butterflies wings possess different types of scales to perform diverse functions. Each scale has many nano and microstructures, which interferes with light, resulting in unique coloration for each butterfly. Besides coloration, the arrangement of scales further helps in giving better survivability. Thus, analysis of wing pattern provides an overall idea about adaptation and activity of the animal. The current study deciphers the structure and composition of a wing of a pierid butterfly Catopsilia pomona, which remains active at 42°C at which temperature all other butterflies face a tougher task for existence...
September 28, 2017: Microscopy
Ian MacLaren, Kirsty J Annand, Colin Black, Alan J Craven
Electron energy-loss spectroscopy (EELS) has been investigated in the range from 2 to >10 keV using an optimized optical coupling of the microscope to the spectrometer to improve the high loss performance in EELS. It is found that excellent quality data can now be acquired up until about 5 keV, suitable for both energy loss near edge structure (ELNES) studies of oxidation and local chemistry, and potentially useful for extended energy loss fine structure (EXELFS) studies of local atomic ordering. Examples studied included oxidation in Zr, Mo and Sn, and the ELNES and EXELFS of the Ti-K edge...
September 21, 2017: Microscopy
Atsunori Oshima
Gap junction channels are essential for mediating intercellular communication in most multicellular organisms. Two gene families encode gap junction channels, innexin and connexin. Although the sequence similarity between these two families based on bioinformatics is not conclusively determined, the gap junction channels encoded by these two gene families are structurally and functionally analogous. We recently reported an atomic structure of an invertebrate innexin gap junction channel using single-particle cryo-electron microscopy...
September 21, 2017: Microscopy
Yunjie Chang, Shouqing Li, Yumei Wang, Binghui Ge
According to transmission cross-coefficient theory, the information limit of non-linear imaging in high-resolution transmission electron microscopy is, under certain conditions, far beyond that of linear imaging, which suggests the possibility of using high-frequency information for structural determination. In this article, we studied the information beyond the linear information limit by means of multislice method simulation, with AlN as an example, and more structural information was obtained by using part of the high-frequency information...
September 11, 2017: Microscopy
Akimitsu Ishizuka, Masaaki Oka, Takehito Seki, Naoya Shibata, Kazuo Ishizuka
The differential phase contrast (DPC) imaging in STEM was mainly used for a study of magnetic material in a medium resolution. An ideal DPC signals give the center of mass of the diffraction pattern, which is proportional to an electric field. Recently, the possibility of the DPC imaging at atomic resolution was demonstrated. Thus, the DPC imaging opens up the possibility to observe the object phase that is proportional to the electrostatic potential.In this report we investigate the numerical procedures to obtain the object phase from the two perpendicular DPC signals...
August 31, 2017: Microscopy
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
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
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
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
S B Bimurzaev, N U Aldiyarov, E M Yakushev
The paper describes the principle of operation of a relatively simple aberration corrector for the transmission electron microscope objective lens. The electron-optical system of the aberration corrector consists of the two main elements: an electrostatic mirror with rotational symmetry and a magnetic deflector formed by the round-shaped magnetic poles. The corrector operation is demonstrated by calculations on the example of correction of basic aberrations of the well-known objective lens with a bell-shaped distribution of the axial magnetic field...
October 1, 2017: Microscopy
Hiroyuki Iwata, Daisuke Kawaguchi, Hiroyasu Saka
Voids formed in Si by permeable laser irradiation were investigated by comprehensive electron microscopy. Two types of voids were identified: Type (1): This type was formed mostly closer to the entrance surface of a laser, and a considerable volume of a non-diamond Si (DS) phase was formed in the surrounding matrix. Type (2): This type was formed at the focus of an incident laser, and none of dislocations, cracks and non-DS phase was observed in the surrounding matrix. Type (1) voids are considered to be formed to accommodate volume change resulting from transformation from DS to the non-DS...
October 1, 2017: Microscopy
Shigekazu Morito, Anh Hoang Pham, Takuya Ohba, Taisuke Hayashi, Tadashi Furuhara, Goro Miyamoto
The lath martensite structure contains hierarchical substructures, such as blocks, packets and prior austenite grains. Generally, high-angle grain boundaries in the lath martensite structure, i.e. block boundaries, are correlated to mechanical properties. On the other hand, low-angle grain boundaries play an important role in morphological development. However, it is difficult to understand their nature because of the difficulty associated with the characterization of the complex morphologies by two-dimensional techniques...
August 9, 2017: Microscopy
Naoki Ogawa, Ryo Mizokawa, Minoru Saito, Akira Ishikawa
With the aid of the environmental cell (EC) in electron microscopy, hydrated specimens have been observed at high resolutions that optical microscopy cannot attain. Due to the ultra-high vacuum conditions of the inner column of the electron microscope, the EC requires sealing films that are sufficiently thin to allow electron transmission and that are sufficiently tough to withstand the pressure difference between the inside and outside of the EC. However, most hydrated specimens can be observed at low vacuum because the saturated vapor pressure of water is known to be 0...
August 9, 2017: Microscopy
Hiroyuki Yamada, Masashi Yamaguchi, Kiminori Shimizu, Somay Yamagata Murayama, Satoshi Mitarai, Chihiro Sasakawa, Hiroji Chibana
Structome analysis, the quantitative three-dimensional structural analysis of whole cells at the electron microscopic level, of Exophiala dermatitidis (black yeast), Saccharomyces cerevisiae, Mycobacterium tuberculosis (MTB) and Myojin spiral bacteria (MSB) have already been reported. Here, the results of the structome analysis of Escherichia coli cells based on transmission electron microscope observation of serial ultrathin sections was reported, and compared with the data obtained from phase contrast microscopy and scanning electron microscopy...
August 1, 2017: Microscopy
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