WorldWideScience

Sample records for aberration-corrected scanning transmission

  1. Aberration corrected Lorentz scanning transmission electron microscopy

    We present results from an aberration corrected scanning transmission electron microscope which has been customised for high resolution quantitative Lorentz microscopy with the sample located in a magnetic field free or low field environment. We discuss the innovations in microscope instrumentation and additional hardware that underpin the imaging improvements in resolution and detection with a focus on developments in differential phase contrast microscopy. Examples from materials possessing nanometre scale variations in magnetisation illustrate the potential for aberration corrected Lorentz imaging as a tool to further our understanding of magnetism on this lengthscale. - Highlights: • Demonstration of nanometre scale resolution in magnetic field free environment using aberration correction in the scanning transmission electron microscope (STEM). • Implementation of differential phase contrast mode of Lorentz microscopy in aberration corrected STEM with improved sensitivity. • Quantitative imaging of magnetic induction of nanostructures in amorphous and cross-section samples

  2. Bright-field imaging of compound semiconductors using aberration-corrected scanning transmission electron microscopy

    Aoki, Toshihiro; Lu, Jing; McCartney, Martha R.; Smith, David J.

    2016-09-01

    This study reports the observation of six different zincblende compound semiconductors in [110] projection using large-collection-angle bright-field (LABF) imaging with an aberration-corrected scanning transmission electron microscope. Phase contrast is completely suppressed when the collection semi-angle is set equal to the convergence semi-angle and there are no reversals in image contrast with changes in defocus or thickness. The optimum focus for imaging closely separated pairs of atomic columns (‘dumbbells’) is unique and easily recognized, and the positions of atomic columns occupied by heavier atoms always have darker intensity than those occupied by lighter atoms. Thus, the crystal polarity of compound semiconductors can be determined unambiguously. Moreover, it is concluded that the LABF imaging mode will be highly beneficial for studying other more complicated heterostructures at the atomic scale.

  3. Aberration-corrected scanning transmission electron microscopy for complex transition metal oxides

    Qing-Hua, Zhang; Dong-Dong, Xiao; Lin, Gu

    2016-06-01

    Lattice, charge, orbital, and spin are the four fundamental degrees of freedom in condensed matter, of which the interactive coupling derives tremendous novel physical phenomena, such as high-temperature superconductivity (high-T c SC) and colossal magnetoresistance (CMR) in strongly correlated electronic system. Direct experimental observation of these freedoms is essential to understanding the structure-property relationship and the physics behind it, and also indispensable for designing new materials and devices. Scanning transmission electron microscopy (STEM) integrating multiple techniques of structure imaging and spectrum analysis, is a comprehensive platform for providing structural, chemical and electronic information of materials with a high spatial resolution. Benefiting from the development of aberration correctors, STEM has taken a big breakthrough towards sub-angstrom resolution in last decade and always steps forward to improve the capability of material characterization; many improvements have been achieved in recent years, thereby giving an in-depth insight into material research. Here, we present a brief review of the recent advances of STEM by some representative examples of perovskite transition metal oxides; atomic-scale mapping of ferroelectric polarization, octahedral distortions and rotations, valence state, coordination and spin ordering are presented. We expect that this brief introduction about the current capability of STEM could facilitate the understanding of the relationship between functional properties and these fundamental degrees of freedom in complex oxides. Project supported by the National Key Basic Research Project, China (Grant No. 2014CB921002), the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDB07030200), and the National Natural Science Foundation of China (Grant Nos. 51522212 and 51421002).

  4. In-situ Study of Dynamic Phenomena at Metal Nanosolder Interfaces Using Aberration Corrected Scanning Transmission Electron Microcopy.

    Lu, Ping

    2014-10-01

    Controlling metallic nanoparticle (NP) interactions plays a vital role in the development of new joining techniques (nanosolder) that bond at lower processing temperatures but remain viable at higher temperatures. The pr imary objective of this project is t o develop a fundamental understanding of the actual reaction processes, associated atomic mechanisms, and the resulting microstructure that occur during thermally - driven bond formation concerning metal - metal nano - scale (<50nm) interfaces. In this LDRD pr oject, we have studied metallic NPs interaction at the elevated temperatures by combining in - situ transmission electron microscopy (TEM ) using an aberration - corrected scanning transmission electron microscope (AC - STEM) and atomic - scale modeling such as m olecular dynamic (MD) simulations. Various metallic NPs such as Ag, Cu and Au are synthesized by chemical routines. Numerous in - situ e xperiments were carried out with focus of the research on study of Ag - Cu system. For the first time, using in - situ STEM he ating experiments , we directly observed t he formation of a 3 - dimensional (3 - D) epitaxial Cu - Ag core - shell nanoparticle during the thermal interaction of Cu and Ag NPs at elevated temperatures (150 - 300 o C). The reaction takes place at temperatures as low as 150 o C and was only observed when care was taken to circumvent the effects of electron beam irradiation during STEM imaging. Atomic - scale modeling verified that the Cu - Ag core - shell structure is energetically favored, and indicated that this phenomenon is a nano - scale effect related to the large surface - to - volume ratio of the NPs. The observation potentially can be used for developing new nanosolder technology that uses Ag shell as the %22glue%22 that stic ks the particles of Cu together. The LDRD has led to several journal publications and numerous conference presentations, and a TA. In addition, we have developed new TEM characterization techniques and phase

  5. Direct imaging of crystal structure and defects in metastable Ge2Sb2Te5 by quantitative aberration-corrected scanning transmission electron microscopy

    Knowledge about the atomic structure and vacancy distribution in phase change materials is of foremost importance in order to understand the underlying mechanism of fast reversible phase transformation. In this Letter, by combining state-of-the-art aberration-corrected scanning transmission electron microscopy with image simulations, we are able to map the local atomic structure and composition of a textured metastable Ge2Sb2Te5 thin film deposited by pulsed laser deposition with excellent spatial resolution. The atomic-resolution scanning transmission electron microscopy investigations display the heterogeneous defect structure of the Ge2Sb2Te5 phase. The obtained results are discussed. Highly oriented Ge2Sb2Te5 thin films appear to be a promising approach for further atomic-resolution investigations of the phase change behavior of this material class

  6. Morphological evolution of InAs/InP quantum wires through aberration-corrected scanning transmission electron microscopy.

    Sales, D L; Varela, M; Pennycook, S J; Galindo, P L; González, L; González, Y; Fuster, D; Molina, S I

    2010-08-13

    Evolution of the size, shape and composition of self-assembled InAs/InP quantum wires through the Stranski-Krastanov transition has been determined by aberration-corrected Z-contrast imaging. High resolution compositional maps of the wires in the initial, intermediate and final formation stages are presented. (001) is the main facet at their very initial stage of formation, which is gradually reduced in favour of [114] or [118], ending with the formation of mature quantum wires with {114} facets. Significant changes in wire dimensions are measured when varying slightly the amount of InAs deposited. These results are used as input parameters to build three-dimensional models that allow calculation of the strain energy during the quantum wire formation process. The observed morphological evolution is explained in terms of the calculated elastic energy changes at the growth front. Regions of the wetting layer close to the nanostructure perimeters have higher strain energy, causing migration of As atoms towards the quantum wire terraces, where the structure is partially relaxed; the thickness of the wetting layer is reduced in these zones and the island height increases until the (001) facet is removed. PMID:20647625

  7. Morphological evolution of InAs/InP quantum wires through aberration-corrected scanning transmission electron microscopy

    Evolution of the size, shape and composition of self-assembled InAs/InP quantum wires through the Stranski-Krastanov transition has been determined by aberration-corrected Z-contrast imaging. High resolution compositional maps of the wires in the initial, intermediate and final formation stages are presented. (001) is the main facet at their very initial stage of formation, which is gradually reduced in favour of {114} or {118}, ending with the formation of mature quantum wires with {114} facets. Significant changes in wire dimensions are measured when varying slightly the amount of InAs deposited. These results are used as input parameters to build three-dimensional models that allow calculation of the strain energy during the quantum wire formation process. The observed morphological evolution is explained in terms of the calculated elastic energy changes at the growth front. Regions of the wetting layer close to the nanostructure perimeters have higher strain energy, causing migration of As atoms towards the quantum wire terraces, where the structure is partially relaxed; the thickness of the wetting layer is reduced in these zones and the island height increases until the (001) facet is removed.

  8. Image transfer with spatial coherence for aberration corrected transmission electron microscopes.

    Hosokawa, Fumio; Sawada, Hidetaka; Shinkawa, Takao; Sannomiya, Takumi

    2016-08-01

    The formula of spatial coherence involving an aberration up to six-fold astigmatism is derived for aberration-corrected transmission electron microscopy. Transfer functions for linear imaging are calculated using the newly derived formula with several residual aberrations. Depending on the symmetry and origin of an aberration, the calculated transfer function shows characteristic symmetries. The aberrations that originate from the field's components, having uniformity along the z direction, namely, the n-fold astigmatism, show rotational symmetric damping of the coherence. The aberrations that originate from the field's derivatives with respect to z, such as coma, star, and three lobe, show non-rotational symmetric damping. It is confirmed that the odd-symmetric wave aberrations have influences on the attenuation of an image via spatial coherence. Examples of image simulations of haemoglobin and Si [211] are shown by using the spatial coherence for an aberration-corrected electron microscope. PMID:27155359

  9. The first observation of titanate nanotubes by spherical aberration corrected high-resolution transmission electron microscopy

    Miao, L.; Tanemura, S.; Jiang, T.; Tanemura, M.; Yoshida, K.; Tanaka, N.; Xu, G.

    2009-07-01

    Multi-wall titanate nanotubes (MW-TNNTs) with high aspect ratio, large surface area and good uniformity were produced by alkaline hydrothermal treatment of grounded TiO 2 aerogels and further by applying freeze-drying. Not only the crystal phase and diameter, but also morphology of the starting materials impact on the aspect ratio and transformation efficiency of the obtained nanotubes. Other parameters, such as pH value during neutralization process and drying method for the final products, are important to control length and dispersion of MW-TNNTs. By spherical aberration corrected high-resolution transmission-electron-microscopy (Cs-corrected HRTEM) with lateral space resolution of 0.14 nm at 200 kV accelerating voltage and electron energy loss spectrum (EELS), the detailed structural analysis of MW-TNNTs reveals that (1) diameters of inner and outer tubes are about 4-7 nm and 10 nm, respectively, (2) numbers of layers are different from part to part along the longitudinal tube axis, (3) the walls of the tubes have interlayer spacing of 0.70-0.80 nm and the lateral fringes which are vertical to the walls have spacing of 0.32 nm, (4) each layer of MW-TNNT is the nanosheet composed by the arrayed TiO 6 octahedrons, and respective octahedron being slightly strained, and (5) no chirality of MW-TNNT tubular structure is observed.

  10. Interaction between single gold atom and the graphene edge: A study via aberration-corrected transmission electron microscopy

    Wang, Hongtao

    2012-01-01

    Interaction between single noble metal atoms and graphene edges has been investigated via aberration-corrected and monochromated transmission electron microscopy. A collective motion of the Au atom and the nearby carbon atoms is observed in transition between energy-favorable configurations. Most trapping and detrapping processes are assisted by the dangling carbon atoms, which are more susceptible to knock-on displacements by electron irradiation. Thermal energy is lower than the activation barriers in transition among different energy-favorable configurations, which suggests electron-beam irradiation can be an efficient way of engineering the graphene edge with metal atoms. © 2012 The Royal Society of Chemistry.

  11. Aberration corrected 1.2-MV cold field-emission transmission electron microscope with a sub-50-pm resolution

    Akashi, Tetsuya; Takahashi, Yoshio; Tanigaki, Toshiaki, E-mail: toshiaki.tanigaki.mv@hitachi.com; Shimakura, Tomokazu; Kawasaki, Takeshi; Furutsu, Tadao; Shinada, Hiroyuki; Osakabe, Nobuyuki [Central Research Laboratory, Hitachi, Ltd., Hatoyama 350-0395 (Japan); Müller, Heiko; Haider, Maximilian [Corrected Electron Optical Systems GmbH, Englerstr. 28, D-69126 Heidelberg (Germany); Tonomura, Akira [Central Research Laboratory, Hitachi, Ltd., Hatoyama 350-0395 (Japan); RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198 (Japan)

    2015-02-16

    Atomic-resolution electromagnetic field observation is critical to the development of advanced materials and to the unveiling of their fundamental physics. For this purpose, a spherical-aberration corrected 1.2-MV cold field-emission transmission electron microscope has been developed. The microscope has the following superior properties: stabilized accelerating voltage, minimized electrical and mechanical fluctuation, and coherent electron emission. These properties have enabled to obtain 43-pm information transfer. On the bases of these performances, a 43-pm resolution has been obtained by correcting lens aberrations up to the third order. Observations of GaN [411] thin crystal showed a projected atomic locations with a separation of 44 pm.

  12. Aberration corrected 1.2-MV cold field-emission transmission electron microscope with a sub-50-pm resolution

    Atomic-resolution electromagnetic field observation is critical to the development of advanced materials and to the unveiling of their fundamental physics. For this purpose, a spherical-aberration corrected 1.2-MV cold field-emission transmission electron microscope has been developed. The microscope has the following superior properties: stabilized accelerating voltage, minimized electrical and mechanical fluctuation, and coherent electron emission. These properties have enabled to obtain 43-pm information transfer. On the bases of these performances, a 43-pm resolution has been obtained by correcting lens aberrations up to the third order. Observations of GaN [411] thin crystal showed a projected atomic locations with a separation of 44 pm

  13. Aberration-corrected transmission electron microscopy analyses of GaAs/Si interfaces in wafer-bonded multi-junction solar cells

    Aberration-corrected scanning transmission electron microscopy (STEM) and electron energy loss spectroscopy (EELS) investigations have been applied to investigate the structure and composition fluctuations near interfaces in wafer-bonded multi-junction solar cells. Multi-junction solar cells are of particular interest since efficiencies well above 40% have been obtained for concentrator solar cells which are based on III-V compound semiconductors. In this methodologically oriented investigation, we explore the potential of combining aberration-corrected high-angle annular dark-field STEM imaging (HAADF-STEM) with spectroscopic techniques, such as EELS and energy-dispersive X-ray spectroscopy (EDXS), and with high-resolution transmission electron microscopy (HR-TEM), in order to analyze the effects of fast atom beam (FAB) and ion beam bombardment (IB) activation treatments on the structure and composition of bonding interfaces of wafer-bonded solar cells on Si substrates. Investigations using STEM/EELS are able to measure quantitatively and with high precision the widths and the fluctuations in element distributions within amorphous interface layers of nanometer extensions, including those of light elements. Such measurements allow the control of the activation treatments and thus support assessing electrical conductivity phenomena connected with impurity and dopant distributions near interfaces for optimized performance of the solar cells. - Highlights: • Aberration-corrected TEM and EELS reveal structural and elemental profiles across GaAs/Si bond interfaces in wafer-bonded GaInP/GaAs/Si - multi-junction solar cells. • Fluctuations in elemental concentration in nanometer-thick amorphous interface layers, including the disrubutions of light elements, are measured using EELS. • The projected widths of the interface layers are determined on the atomic scale from STEM-HAADF measurements. • The effects of atom and ion beam activation treatment on the bonding

  14. Aberration corrected and monochromated environmental transmission electron microscopy: challenges and prospects for materials science

    Hansen, Thomas Willum; Wagner, Jakob Birkedal; Dunin-Borkowski, Rafal E.

    2010-01-01

    The latest generation of environmental transmission electron microscopes incorporates aberration correctors and monochromators, allowing studies of chemical reactions and growth processes with improved spatial resolution and spectral sensitivity. Here, we describe the performance of such an instr...

  15. High-resolution adaptive optics scanning laser ophthalmoscope with dual deformable mirrors for large aberration correction

    Chen, D; Jones, S M; Silva, D A; Olivier, S S

    2007-01-25

    Scanning laser ophthalmoscopes with adaptive optics (AOSLO) have been shown previously to provide a noninvasive, cellular-scale view of the living human retina. However, the clinical utility of these systems has been limited by the available deformable mirror technology. In this paper, we demonstrate that the use of dual deformable mirrors can effectively compensate large aberrations in the human retina, making the AOSLO system a viable, non-invasive, high-resolution imaging tool for clinical diagnostics. We used a bimorph deformable mirror to correct low-order aberrations with relatively large amplitudes. The bimorph mirror is manufactured by Aoptix, Inc. with 37 elements and 18 {micro}m stroke in a 10 mm aperture. We used a MEMS deformable mirror to correct high-order aberrations with lower amplitudes. The MEMS mirror is manufactured by Boston Micromachine, Inc with 144 elements and 1.5 {micro}m stroke in a 3 mm aperture. We have achieved near diffraction-limited retina images using the dual deformable mirrors to correct large aberrations up to {+-} 3D of defocus and {+-} 3D of cylindrical aberrations with test subjects. This increases the range of spectacle corrections by the AO systems by a factor of 10, which is crucial for use in the clinical environment. This ability for large phase compensation can eliminate accurate refractive error fitting for the patients, which greatly improves the system ease of use and efficiency in the clinical environment.

  16. Effect of oxygen stoichiometry in LuFe2O(4-δ) and its microstructure observed by aberration-corrected transmission electron microscopy.

    Yang, H X; Tian, H F; Wang, Z; Qin, Y B; Ma, C; Li, J Q; Cheng, Z Y; Yu, R; Zhu, J

    2012-10-31

    A series of oxygen deficient LuFe(2)O(4-δ) materials have been prepared under a controlled oxygen partial-pressure atmosphere. Measurements of magnetization reveal that the increase of oxygen deficiencies could evidently depress the ferrimagnetic phase transition temperature (T(N)). In additional to the well-known charge ordering within the (11(-)0) crystal plane, a visible structural modulation with q = (0,1/4.2,7/8) commonly appears on the (100) plane in the oxygen deficient samples. An aberration-corrected transmission electron microscopy study on the oxygen deficient samples demonstrates the presence of oxygen vacancies and local structural distortion. The atomic structural features in correlation with the structural modulation, distortion of the FeO(5) polyhedron and the (001) twinning domains have been also examined. PMID:23032863

  17. A ‘jump-to-coalescence’ mechanism during nanoparticle growth revealed by in situ aberration-corrected transmission electron microscopy observations

    Neng, Wan; Shuang-ying, Lei; Jun, Xu; Martini, Matteo

    2016-05-01

    In this work, we used in situ aberration-corrected transmission electron microscopy (AC-TEM) to observe the coalescence of gold nanoparticles. We observed a critical edge-to-edge distance {d}ec∼ 0.5 {nm} below which the two particles will coalesce rapidly (jump-to-coalescence). A model based on the single-atom-triggered rapid particle contraction was proposed and verified by first-principles calculations, in which evident energy decrease was detected when adding a gold atom between two gold nanoparticles. Our ex situ TEM study of sputtering-deposited gold nanoparticles on different substrates with varied time also supports the jump-to-contact mechanism. This observation afforded physical insight into the fundamental growth mechanism during dynamic particle coalescence processes.

  18. Aberration Corrected Emittance Exchange

    Nanni, Emilio A

    2015-01-01

    Full exploitation of emittance exchange (EEX) requires aberration-free performance of a complex imaging system including active radio-frequency (RF) elements which can add temporal distortions. We investigate the performance of an EEX line where the exchange occurs between two dimensions with normalized emittances which differ by orders of magnitude. The transverse emittance is exchanged into the longitudinal dimension using a double dog-leg emittance exchange setup with a 5 cell RF deflector cavity. Aberration correction is performed on the four most dominant aberrations. These include temporal aberrations that are corrected with higher order magnetic optical elements located where longitudinal and transverse emittance are coupled. We demonstrate aberration-free performance of emittances differing by 4 orders of magnitude, i.e. an initial transverse emittance of $\\epsilon_x=1$ pm-rad is exchanged with a longitudinal emittance of $\\epsilon_z=10$ nm-rad.

  19. Evaluation of stacking faults and associated partial dislocations in AlSb/GaAs (001) interface by aberration-corrected high-resolution transmission electron microscopy

    The stacking faults (SFs) in an AlSb/GaAs (001) interface were investigated using a 300 kV spherical aberration-corrected high-resolution transmission electron microscope (HRTEM). The structure and strain distribution of the single and intersecting (V-shaped) SFs associated with partial dislocations (PDs) were characterized by the [110] HRTEM images and geometric phase analysis, respectively. In the biaxial strain maps εxx and εyy, a SF can be divided into several sections under different strain states (positive or negative strain values). Furthermore, the strain state for the same section of a SF is in contrast to each other in εxx and εyy strain maps. The modification in the strain states was attributed to the variation in the local atomic displacements for the SF in the AlSb film on the GaAs substrate recorded in the lattice image. Finally, the single SF was found to be bounded by two 30° PDs. A pair of 30° PDs near the heteroepitaxial interface reacted to form a Lomer-Cottrell sessile dislocation located at the vertices of V-shaped SFs with opposite screw components. The roles of misfit dislocations, such as the PDs, in strain relaxation were also discussed

  20. Brief history of the Cambridge STEM aberration correction project and its progeny

    We provide a brief history of the project to correct the spherical aberration of the scanning transmission electron microscope (STEM) that started in Cambridge (UK) and continued in Kirkland (WA, USA), Yorktown Heights (NY, USA), and other places. We describe the project in the full context of other aberration correction research and related work, partly in response to the incomplete context presented in the paper “In quest of perfection in electron optics: A biographical sketch of Harald Rose on the occasion of his 80th birthday”, recently published in Ultramicroscopy. - Highlights: • We provide a brief history of the Cambridge project to correct the spherical aberration of the scanning transmission electron microscope (STEM). • We describe the project in the full context of other aberration correction work and related research. • We summarize our corrector development work that followed the Cambridge project, and which was the first to reach higher spatial resolution than any non-corrected electron microscope

  1. Brief history of the Cambridge STEM aberration correction project and its progeny

    Brown, L. Michael [Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Batson, Philip E. [Institute for Advanced Materials, Devices and Nanotechnology, Rutgers University, Piscataway, NJ 08854 (United States); Department of Physics, Rutgers University, Piscataway, NJ 08854 (United States); Department of Materials Science, Rutgers University, Piscataway, NJ 08854 (United States); Dellby, Niklas [Nion Company, 11515 NE 118th Street, Kirkland, WA 98034 (United States); Krivanek, Ondrej L. [Nion Company, 11515 NE 118th Street, Kirkland, WA 98034 (United States); Department of Physics, Arizona State University, Tempe, AZ 85287 (United States)

    2015-10-15

    We provide a brief history of the project to correct the spherical aberration of the scanning transmission electron microscope (STEM) that started in Cambridge (UK) and continued in Kirkland (WA, USA), Yorktown Heights (NY, USA), and other places. We describe the project in the full context of other aberration correction research and related work, partly in response to the incomplete context presented in the paper “In quest of perfection in electron optics: A biographical sketch of Harald Rose on the occasion of his 80th birthday”, recently published in Ultramicroscopy. - Highlights: • We provide a brief history of the Cambridge project to correct the spherical aberration of the scanning transmission electron microscope (STEM). • We describe the project in the full context of other aberration correction work and related research. • We summarize our corrector development work that followed the Cambridge project, and which was the first to reach higher spatial resolution than any non-corrected electron microscope.

  2. Aberration-corrected STEM and EELS of semiconducting nanostructures

    We review some applications of aberration–corrected electron microscopy for the detailed characterization of semiconducting nanostructures using a combination of high-angle annular dark-field scanning transmission electron microscopy and electron energy loss spectroscopy. The study of self-assembled quantum wires shows that it is possible to determine the composition of the nanostructures with better than 1 nm resolution down to the atomic level while the contrast in the high-angle annular dark-field images is used to determine the presence of wetting layers separating quantum wires and the strain field arising from the local compositional changes. The local measurements of energy loss spectra demonstrate the shift of plasmon peaks consistent with the changes in lattice parameters. High-angle annular dark-field images are also used to study the contrast in GaSb thin films deposited and study the presence of anti-phase domain boundaries. These examples show that aberration-corrected microscopy combined with electron energy loss spectroscopy provide not only enhanced resolution but also increased sensitivity to atomic site compositional changes.

  3. New Views of Materials through Aberration-Corrected STEM

    Pennycook, Stephen J [ORNL; Chisholm, Matthew F [ORNL; Lupini, Andrew R [ORNL; Varela del Arco, Maria [ORNL; Borisevich, Albina Y [ORNL; Pantelides, Sokrates T. [Vanderbilt University; van Benthem, Klaus [ORNL; Shibata, Naoya [University of Tokyo, Tokyo, Japan; Molina Rubio, Sergio I [ORNL; Rashkeev, Sergey [ORNL

    2009-01-01

    The successful correction of lens aberrations in scanning transmission electron microscopy has allowed an improvement in resolution by a factor of two in just a few years. The benefits for materials research are far greater than a factor of two might imply, because enhanced resolution also brings enhanced image contrast, and therefore a vast increase in sensitivity to single atoms, both for imaging and electron energy loss spectroscopy. In addition, aberration correction enables simultaneous, aberrationcorrected, Z-contrast and phase contrast imaging, and brings a depth resolution at the nanometer level. It becomes possible to focus directly on features at different depths in the specimen thickness, and three-dimensional information can be extracted with single atom sensitivity. In conjunction with density functional and elasticity theory, these advances provide a new level of insight into the atomistic origins of materials properties. Several examples are discussed that illustrate the potential for applications, including the segregation of rare earth elements to grain boundaries in Si3N4 ceramics, the quantitative analysis of strain-induced growth phenomena in semiconductor quantum wells, the explanation of the enhanced thermal stability of La-doped -alumina as a catalyst support, and the origin of the remarkable catalytic activity of Au nanoparticles.

  4. Optical advantages of astigmatic aberration corrected heliostats

    van Rooyen, De Wet; Schöttl, Peter; Bern, Gregor; Heimsath, Anna; Nitz, Peter

    2016-05-01

    Astigmatic aberration corrected heliostats adapt their shape in dependence of the incidence angle of the sun on the heliostat. Simulations show that this optical correction leads to a higher concentration ratio at the target and thus in a decrease in required receiver aperture in particular for smaller heliostat fields.

  5. Catadioptric aberration correction in cathode lens microscopy

    Tromp, R.M. [IBM T.J. Watson Research Center, PO Box 218, Yorktown Heights, NY 10598 (United States); Kamerlingh Onnes Laboratory, Leiden Institute of Physics, Niels Bohrweg 2, 2333 CA Leiden (Netherlands)

    2015-04-15

    In this paper I briefly review the use of electrostatic electron mirrors to correct the aberrations of the cathode lens objective lens in low energy electron microscope (LEEM) and photo electron emission microscope (PEEM) instruments. These catadioptric systems, combining electrostatic lens elements with a reflecting mirror, offer a compact solution, allowing simultaneous and independent correction of both spherical and chromatic aberrations. A comparison with catadioptric systems in light optics informs our understanding of the working principles behind aberration correction with electron mirrors, and may point the way to further improvements in the latter. With additional developments in detector technology, 1 nm spatial resolution in LEEM appears to be within reach. - Highlights: • The use of electron mirrors for aberration correction in LEEM/PEEM is reviewed. • A comparison is made with similar systems in light optics. • Conditions for 1 nm spatial resolution are discussed.

  6. Catadioptric aberration correction in cathode lens microscopy

    In this paper I briefly review the use of electrostatic electron mirrors to correct the aberrations of the cathode lens objective lens in low energy electron microscope (LEEM) and photo electron emission microscope (PEEM) instruments. These catadioptric systems, combining electrostatic lens elements with a reflecting mirror, offer a compact solution, allowing simultaneous and independent correction of both spherical and chromatic aberrations. A comparison with catadioptric systems in light optics informs our understanding of the working principles behind aberration correction with electron mirrors, and may point the way to further improvements in the latter. With additional developments in detector technology, 1 nm spatial resolution in LEEM appears to be within reach. - Highlights: • The use of electron mirrors for aberration correction in LEEM/PEEM is reviewed. • A comparison is made with similar systems in light optics. • Conditions for 1 nm spatial resolution are discussed

  7. Aberration corrected environmental STEM (AC ESTEM) for dynamic in-situ gas reaction studies of nanoparticle catalysts

    Environmental scanning transmission electron microscopy (ESTEM) with aberration correction (AC) has recently been added to the capabilities of the more established ETEM for analysis of heterogeneous nanoparticle based catalysts. It has helped to reveal the importance and potentially unique properties of individual atoms as active sites in their own right as well as pathways between established nanoparticles. A new capability is introduced for dynamic in-situ experiments under controlled conditions of specimen temperature and gas environment related to real world conditions pertinent to a range of industrial and societal priorities for new and improved chemical processes, materials, fuels, pharmaceutical products and processes, and in control or remediation of environmental emissions

  8. Aberration-corrected imaging of active sites on industrial catalyst nanoparticles

    Gontard, Lionel Cervera; Chang, L-Y; Hetherington, CJD;

    2007-01-01

    Picture perfect: Information about the local topologies of active sites on commercial nanoparticles can be gained with atomic resolution through spherical-aberration-corrected transmission electron microscopy (TEM). A powder of Pt nanoparticles on carbon black was examined with two advanced TEM...

  9. Aberration-corrected STEM/TEM imaging at 15 kV

    Sasaki, Takeo, E-mail: tasasaki@jeol.co.jp [EM Business Unit, JEOL Ltd., 3-1-2 Musashino, Akishima, Tokyo 196-8558 (Japan); Sawada, Hidetaka; Hosokawa, Fumio [EM Business Unit, JEOL Ltd., 3-1-2 Musashino, Akishima, Tokyo 196-8558 (Japan); Sato, Yuta; Suenaga, Kazu [Nanotube Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 5, Higashi 1-1-1, Tsukuba, Ibaraki 305-8565 (Japan)

    2014-10-15

    The performance of aberration-corrected (scanning) transmission electron microscopy (S/TEM) at an accelerating voltage of 15 kV was evaluated in a low-voltage microscope equipped with a cold-field emission gun and a higher-order aberration corrector. Aberrations up to the fifth order were corrected by the aberration measurement and auto-correction system using the diffractogram tableau method in TEM and Ronchigram analysis in STEM. TEM observation of nanometer-sized particles demonstrated that aberrations up to an angle of 50 mrad were compensated. A TEM image of Si[110] exhibited lattice fringes with a spacing of 0.192 nm, and the power spectrum of the image showed spots corresponding to distances of 0.111 nm. An annular dark-field STEM image of Si[110] showed lattice fringes of (111) and (22¯0) planes corresponding to lattice distances of 0.314 nm and 0.192 nm, respectively. At an accelerating voltage of 15 kV, the developed low-voltage microscope achieved atomic-resolution imaging with a small chromatic aberration and a large uniform phase. - Highlights: • Aberration-corrected STEM/TEM imaging at 15 kV demonstrated lattice fringes of Si[110] single crystal with a spacing of 0.192 nm. • To achieve this performance at a lower accelerating voltage, uniform phase area over 50 mrad is mandatory in Ronchigram and Diffractogram tableau. • This means a higher-order aberration of six-fold astigmatism should be compensated. • In addition, decreasing the effect of chromatic aberration plays an important role for improving the performance of linear scattering component at 15 kV TEM.

  10. Atomic-resolution scanning transmission electron microscopy through 50-nm-thick silicon nitride membranes

    Ramachandra, Ranjan; Demers, Hendrix; de Jonge, Niels

    2011-01-01

    Silicon nitride membranes can be used for windows of environmental chambers for in situ electron microscopy. We report that aberration corrected scanning transmission electron microscopy (STEM) achieved atomic resolution on gold nanoparticles placed on both sides of a 50-nm-thick silicon nitride membrane at 200 keV electron beam energy. Spatial frequencies of 1∕1.2 Å were visible for a beam semi-angle of 26.5 mrad. Imaging though a 100-nm-thick membrane was also tested. The achieved imaging c...

  11. Aberration corrected STEM of iron rhodium nanoislands

    McLaren, M. J.; Hage, F. S.; Loving, M.; Ramasse, Q. M.; Lewis, L. H.; Marrows, C. H.; Brydson, R. M. D.

    2014-06-01

    Iron-rhodium (FeRh) nanoislands of equiatomic composition have been analysed using scanning transmission electron microscopy (STEM) electron energy loss spec-troscopy(EELS) and high angle annular dark field (HAADF) techniques. Previous magne-tometry results have lead to a hypothesis that at room temperature the core of the islands are antiferromagnetic while the shell has a small ferromagnetic signal. The causes of this effect are most likely to be a difference in composition at the edges or a strain on the island that stretches the lattice and forces the ferromagnetic transition. The results find, at the film-substrate interface, an iron-rich layer ~ 5 Å thick that could play a key role in affecting the magnetostructural transition around the interfacial region and account for the room temperature ferromagnetism.

  12. Isoplanatic patch size for aberration correction in ultrasonic imaging

    Pilkington, Wayne C.

    Methods and experimental results are described for determination of the region size in an aberrating medium over which a single set of aberration estimates can achieve satisfactory b-scan resolution ( i.e., the isoplanatic patch) using time-shift compensation for aberration correction of ultrasonic transmit and receive beams. Based on twenty percent allowable increases in the -12 dB width of the receive or transmit beam focus using cross-correction compared to self-correction, the isoplanatic patch sizes were found to between 3 and 5 millimeters laterally for a linearly-scanned transducer, and at least 12 millimeters axially for a target distance of 55 millimeters and aberration comparable to human abdominal wall. These sizes depend on the aberration severity, reference site axial position, and allowable resolution degradation with cross-correction. The lateral isoplanatic patch size of a linearly scanned image can be more than doubled to match that of a beam-steered acquisition using aberration estimate position matching relative to the tissue surface. Further expansion of the lateral isoplanatic patch size by an additional 50 to 100 percent for both scanning methods is also shown through propagation path matched cross-correction mapping of aberration estimates. The specific mapping required to achieve the best propagation path match depends on the axial distribution of the aberrating structures, the focal depth being imaged, and the cross-correction distance. The effectiveness of alternate methods to derive propagation path matching maps with and without a priori knowledge of aberrator spatial distribution are contrasted; and a means to dynamically adjust correction maps to maximize isoplanatic patch sizes is proposed and verified. Lateral cross-correction mapping and the map changes required for each cross-correction distance can all be implemented with simple shifting of aberration estimates within the transducer aperture. Therefore, use of optimally mapped

  13. Structural investigation of precipitates with Cu and Zn atomic columns in Al-Mg-Si alloys by aberration-corrected HAADF-STEM

    Precipitates in Al-Mg-Si alloys with Cu addition (∼0.1 wt%) and Zn addition (∼1 wt%) were investigated by aberration corrected high angle annular dark field scanning transmission electron microscopy (HAADF-STEM). Most precipitates had no overall unit cell but contained ordered network of Si atomic columns for both the Cu and the Zn containing precipitates. It was found that both Cu and Zn atomic columns are located at specific sites and producing characteristic local configurations on the Si atomic columns

  14. Three-Dimensional scanning transmission electron microscopy of biological specimens

    De Jonge, Niels

    2010-01-18

    A three-dimensional (3D) reconstruction of the cytoskeleton and a clathrin-coated pit in mammalian cells has been achieved from a focal-series of images recorded in an aberration-corrected scanning transmission electron microscope (STEM). The specimen was a metallic replica of the biological structure comprising Pt nanoparticles 2-3 nm in diameter, with a high stability under electron beam radiation. The 3D dataset was processed by an automated deconvolution procedure. The lateral resolution was 1.1 nm, set by pixel size. Particles differing by only 10 nm in vertical position were identified as separate objects with greater than 20% dip in contrast between them. We refer to this value as the axial resolution of the deconvolution or reconstruction, the ability to recognize two objects, which were unresolved in the original dataset. The resolution of the reconstruction is comparable to that achieved by tilt-series transmission electron microscopy. However, the focal-series method does not require mechanical tilting and is therefore much faster. 3D STEM images were also recorded of the Golgi ribbon in conventional thin sections containing 3T3 cells with a comparable axial resolution in the deconvolved dataset. © 2010 Microscopy Society of America.

  15. Characterization of surface metallic states in SrTiO3 by means of aberration corrected electron microscopy.

    Sánchez-Santolino, G; Tornos, J; Bruno, F Y; Cuellar, F A; Leon, C; Santamaría, J; Pennycook, S J; Varela, M

    2013-04-01

    An unusual conducting surface state can be produced in SrTiO3 substrates by irradiation with Argon ions from a plasma source, at low energy and high doses. The effects of irradiation are analyzed here by atomic force microscopy (AFM) and aberration corrected scanning transmission electron microscopy (STEM) combined with electron energy loss spectroscopy (EELS). Depth sensitive studies demonstrate the existence of a heavily damaged surface layer and an oxygen vacancy rich layer immediately underneath, both induced during the irradiation process. We find a clear dependence of the Ti oxidation state with the depth, with a very intense Ti(3+) component near the surface. Oxygen vacancies act as n-type doping by releasing electrons into the lattice and producing an insulator-to-metal transition, which explains the unusual metallic behavior of these samples. PMID:22940531

  16. Picometre-precision analysis of scanning transmission electron microscopy images of platinum nanocatalysts

    Yankovich, Andrew B.; Berkels, Benjamin; Dahmen, W.; Binev, P.; Sanchez, S. I.; Bradley, S. A.; Li, Ao; Szlufarska, Izabela; Voyles, Paul M.

    2014-06-01

    Measuring picometre-scale shifts in the positions of individual atoms in materials provides new insight into the structure of surfaces, defects and interfaces that influence a broad variety of materials’ behaviour. Here we demonstrate sub-picometre precision measurements of atom positions in aberration-corrected Z-contrast scanning transmission electron microscopy images based on the non-rigid registration and averaging of an image series. Non-rigid registration achieves five to seven times better precision than previous methods. Non-rigidly registered images of a silica-supported platinum nanocatalyst show pm-scale contraction of atoms at a ()/() corner towards the particle centre and expansion of a flat () facet. Sub-picometre precision and standardless atom counting with atom uncertainty in the same scanning transmission electron microscopy image provide new insight into the three-dimensional atomic structure of catalyst nanoparticle surfaces, which contain the active sites controlling catalytic reactions.

  17. Structural transformation of tungsten oxide nanourchins into IF-WS2 nanoparticles: an aberration corrected STEM study

    Leonard-Deepak, Francis; Castro-Guerrero, Carlos Fernando; Mejía-Rosales, Sergio; José-Yacamán, Miguel

    2011-12-01

    IF-WS2 nanoparticles synthesized starting from tungsten oxide nanourchins have been investigated by using aberration corrected scanning transmission electron microscopy (Cs-STEM). The synthesis process produced IF-WS2 nanoparticles of two different and well differentiated ranges of size. High resolution HAADF-STEM images and their comparison with simulated STEM micrographs reveal the predominance of stacking of the type 1T close to the border of the structure; the observation of this kind of stacking, observed previously in IF-MoS2 but never reported before in the case of the IF-WS2 nanostructures, adds a new dimension to the existing understanding of structure and stacking in the case of the nanostructures of transition metal chalcogenides.IF-WS2 nanoparticles synthesized starting from tungsten oxide nanourchins have been investigated by using aberration corrected scanning transmission electron microscopy (Cs-STEM). The synthesis process produced IF-WS2 nanoparticles of two different and well differentiated ranges of size. High resolution HAADF-STEM images and their comparison with simulated STEM micrographs reveal the predominance of stacking of the type 1T close to the border of the structure; the observation of this kind of stacking, observed previously in IF-MoS2 but never reported before in the case of the IF-WS2 nanostructures, adds a new dimension to the existing understanding of structure and stacking in the case of the nanostructures of transition metal chalcogenides. Electronic supplementary information (ESI) available: Raman spectra of the WOx-W18O49 nanourchins, XRD pattern, EDAX spectrum and elemental maps of the IF-WS2 nanoparticles. See DOI: 10.1039/c1nr10862j

  18. Understanding the structure of nanocatalysts with high resolution scanning/transmission electron microscopy

    Nanomaterials including nanoparticles, nanowires and nanotubes play an important role in heterogeneous catalysis. Thanks to the rapid improvement of the electron microscopic techniques and with the advent of aberration corrected electron microscopy as well as theoretical methodologies, the potential effects induced by nanocatalysts are better understood than before by unravelling their atomic structure. A brief introduction to advanced electron microscopic techniques namely aberration corrected scanning transmission electron microscopy (Cs-STEM) is presented and subsequently two examples of nanocatalysts are considered in the present review. The first example will focus on the study of bimetallic/core-shell nanoalloys. In heterogeneous catalysis, catalysts containing two or more metals might show significantly different catalytic properties compared to the parent metals and thus are widely utilized in several catalytic reactions. Atom-by-atom insights of the nanoalloy based catalysts ex: Au-Pd will be described in the present review using a combination of advanced electron microscopic and spectroscopic techniques. A related example on the understanding of bimetallic clusters by HAADF-STEM will also be presented in addition to nanoparticles. In the second case understanding the structure of transition metal chalcogenide based nanocatalysts by HRTEM and aberration corrected STEM, for the case of MoS2 will be discussed. MoS2-based catalysts serve as model catalysts and are employed in the hydrodesulphurisations (HDS) reactions in the removal of sulphur from gasoline and related petrochemical products. They have been studied in various forms including nanowires, nanotubes and nanoplates. Their structure, atomic insights and as a consequence elucidation of their corresponding catalytic activity are thus important

  19. Environmental TEM in an Aberration Corrected Microscope

    Hansen, Thomas Willum; Wagner, Jakob Birkedal

    ‐resolution imaging. A gaseous atmosphere in the pole‐piece gap of the objective lens of the microscope alters both the incoming electron wave prior to interaction with the sample and the outgoing wave below the sample. Whereas conventional TEM samples are usually thin (below 10‐20 nm), the gas in the environmental...... microscope column. The effects of gas on the electron wave in the objective lens are not well understood and needs further attention. Imaging samples with a simple geometry, such as gold particles on a flat graphene substrate and analyzing the variations in contrast, provides a means for understanding the...... results from imaging in various elemental as well as di‐molecular gases and their effect on imaging and spectroscopy in the environmental transmission electron microscope....

  20. Probing core-electron orbitals by scanning transmission electron microscopy and measuring the delocalization of core-level excitations

    Jeong, Jong Seok; Odlyzko, Michael L.; Xu, Peng; Jalan, Bharat; Mkhoyan, K. Andre

    2016-04-01

    By recording low-noise energy-dispersive x-ray spectroscopy maps from crystalline specimens using aberration-corrected scanning transmission electron microscopy, it is possible to probe core-level electron orbitals in real space. Both the 1 s and 2 p orbitals of Sr and Ti atoms in SrTi O3 are probed, and their projected excitation potentials are determined. This paper also demonstrates experimental measurement of the electronic excitation impact parameter and the delocalization of an excitation due to Coulombic beam-orbital interaction.

  1. Aberration-corrected electron microscopy of MnAs and As nanocrystals and voids in annealed (Ga,Mn)As

    Kovács, András; Kasama, Takeshi; Sadowski, J.;

    2011-01-01

    Aberration-corrected transmission electron microscopy is used to study voids and nano-crystalline MnAs and As phases formed during the annealing of Mn-doped GaAs. The effects of defocus and inner annular dark-field detector semi-angle on contrast of the nanocrystals are discussed....

  2. The influence of C{sub s}/C{sub c} correction in analytical imaging and spectroscopy in scanning and transmission electron microscopy

    Zaluzec, Nestor J., E-mail: zaluzec@microscopy.com

    2015-04-15

    Aberration correction in scanning/transmission electron microscopy (S/TEM) owes much to the efforts of a small dedicated group of innovators. Leading that frontier has been Prof. Harald Rose. To date his leadership and dynamic personality has spearheaded our ability to leave behind many of the limitations imposed by spherical aberration (C{sub s}) in high resolution phase contrast imaging. Following shortly behind, has been the development of chromatic aberration correction (C{sub c}) which augments those accomplishments. In this paper we will review and summarize how the combination of C{sub s}/C{sub c} technology enhances our ability to conduct hyperspectral imaging and spectroscopy in today's and future computationally mediated experiments in both thin as well as realistic specimens in vacuo and during in-situ/environmental experiments.

  3. In-situ environmental (scanning) transmission electron microscopy of catalysts at the atomic level

    Observing reacting single atoms on the solid catalyst surfaces under controlled reaction conditions is a key goal in understanding and controlling heterogeneous catalytic reactions. In-situ real time aberration corrected environmental (scanning) transmission electron microscopy (E(S)TEM permit the direct imaging of dynamic surface and sub-surface structures of reacting catalysts. In this paper in-situ AC ETEM and AC ESTEM studies under controlled reaction environments of oxide catalysts and supported metal nanocatalysts important in chemical industry are presented. They provide the direct evidence of dynamic processes at the oxide catalyst surface at the atomic scale and single atom dynamics in catalytic reactions. The ESTEM studies of single atom dynamics in controlled reaction environments show that nanoparticles act as reservoirs of ad-atoms. The results have important implications in catalysis and nanoparticle studies

  4. Monochromated scanning transmission electron microscopy

    Full text: Electron energy-loss spectroscopy (EELS) has developed into an established technique for chemical and structural analysis of thin specimens in the (scanning) transmission electron microscope (S)TEM. The energy resolution in EELS is largely limited by the stability of the high voltage supply, by the resolution of the spectrometer and by the energy spread of the source. To overcome this limitation a Wien filter monochromator was recently introduced with commercially available STEMs, offering the advantage to better resolve EELS fine structures, which contain valuable bonding information. The method of atomic resolution Z-contrast imaging within an STEM, utilizing a high-angle annular dark-field (HAADF) detector can perfectly complement the excellent energy resolution, since EELS spectra can be collected simultaneously. In combination with a monochromator microscope not only high spatial resolution images can be recorded but also high energy resolution EELS spectra are attainable. In this work we investigated the STEM performance of a 200 kV monochromated Tecnai F20 with a high resolution Gatan Imaging Filter (HR-GIF). (author)

  5. Environmental Transmission Electron Microscopy in an Aberration-Corrected Environment

    Hansen, Thomas W.; Wagner, Jakob B.

    2012-01-01

    -resolution imaging. A gaseous atmosphere in the pole-piece gap of the objective lens of the microscope alters both the incoming electron wave prior to interaction with the sample and the outgoing wave below the sample. Whereas conventional TEM samples are usually thin (below 100 nm), the gas in the environmental...

  6. Intrinsic Instability of Aberration-Corrected Electron Microscopes

    Schramm, S M; Tromp, R M

    2012-01-01

    Aberration-corrected microscopes with sub-atomic resolution will impact broad areas of science and technology. However, the experimentally observed lifetime of the corrected state is just a few minutes. Here we show that the corrected state is intrinsically unstable; the higher its quality, the more unstable it is. Analyzing the Contrast Transfer Function near optimum correction, we define an 'instability budget' which allows a rational trade-off between resolution and stability. Unless control systems are developed to overcome these challenges, intrinsic instability poses a fundamental limit to the resolution practically achievable in the electron microscope.

  7. Phase aberration correction by multi-stencils fast marching method using sound speed image in ultrasound computed tomography

    Qu, Xiaolei; Azuma, Takashi; Lin, Hongxiang; Imoto, Haruka; Tamano, Satoshi; Takagi, Shu; Umemura, Shin-Ichiro; Sakuma, Ichiro; Matsumoto, Yoichiro

    2016-04-01

    Reflection image from ultrasound computed tomography (USCT) system can be obtained by synthetic aperture technique, however its quality is decreased by phase aberration caused by inhomogeneous media. Therefore, phase aberration correction is important to improve image quality. In this study, multi-stencils fast marching method (MSFMM) is employed for phase correction. The MSFMM is an accurate and fast solution of Eikonal equation which considers the refraction. The proposed method includes two steps. First, the MSFMM is used to compute sound propagation time from each element to each image gird point using sound speed image of USCT. Second, synthetic aperture technique is employed to obtain reflection image using the computed propagation time. To evaluate the proposed method, both numerical simulation and phantom experiment were conducted. With regard to numerical simulation, both quantitative and qualitative comparisons between reflection images with and without phase aberration correction were given. In the quantitative comparison, the diameters of point spread function (PSF) in reflection images of a two layer structure were presented. In the qualitative comparison, reflection images of simple circle and complex breast modes with phase aberration correction show higher quality than that without the correction. In respect to phantom experiment, a piece of breast phantom with artificial glandular structure inside was scanned by a USCT prototype, and the artificial glandular structure is able to be visible more clearly in the reflection image with phase aberration correction than in that without the correction. In this study, a phase aberration correction method by the MSFMM are proposed for reflection image of the USCT.

  8. Aberration corrected imaging of a carbon nanotube encapsulated Lindqvist Ion and correlation with Density Functional Theory

    Sloan, J.; Bichoutskaia, E.; Liu, Z.; Kuganathan, N.; Faulques, E.; Suenaga, K.; Shannon, I. J.

    2012-07-01

    80 kV aberration-corrected transmission electron microscopy (AC-TEM) of discrete [W6O19]2- polyoxometalate ions mounted within double walled carbon nanotubes (DWNTs) allow high precision structural studies to be performed. W atom column separations within the octahedral W6 tungsten template can be visualized with sufficient clarity that correlation with full-scale density functional theory (DFT) can be achieved. Calculations performed on the gas phase and DWNT-mounted [W6O19]2- anions show good agreement, in the latter case, with measured separations between pairs of W2 atom columns imaged within equatorial WO6 octahedra and single W atoms within axial WO6 octahedra. Structural data from the tilted chiral encapsulating DWNT was also determined simultaneously with the anion structural measurements, allowing the nanotube conformation to be addressed in the DFT calculations.

  9. An Aberration Corrected Photoemission Electron Microscope at the Advanced Light Source

    Design of a new aberration corrected Photoemission electron microscope PEEM3 at the Advanced Light Source is outlined. PEEM3 will be installed on an elliptically polarized undulator beamline and will be used for the study of complex materials at high spatial and spectral resolution. The critical components of PEEM3 are the electron mirror aberration corrector and aberration-free magnetic beam separator. The models to calculate the optical properties of the electron mirror are discussed. The goal of the PEEM3 project is to achieve the highest possible transmission of the system at resolutions comparable to our present PEEM2 system (50 nm) and to enable significantly higher resolution, albeit at the sacrifice of intensity. We have left open the possibility to add an energy filter at a later date, if it becomes necessary driven by scientific need to improve the resolution further

  10. Adaptive temporal and wavefront aberration correction for ultrafast lasers with a membrane deformable mirror

    Sherman, Leah Bruner

    Two adaptive optic systems for correction of either temporal phase error and wavefront errors for ultrafast pulses are demonstrated. These systems consists of a computer controlled micromachined membrane deformable mirror (MMDM) and a genetic learning algorithm (GA). Nonlinear excitation such as two-photon fluorescence or second harmonic generation are used as feedback to the GA to determine the appropriate correction to apply to the mirror. Two MMDMs are used, a 30 x 8 mm, 39 actuator linear MMDM for pulse-shaping applications and a 15 mm diameter, 37 actuator wavefront MMDM. Linear pre-compensation of self-phase modulation (SPM) was experimentally demonstrated utilizing the linear MMDM in a linear pulse-shaper for ultrafast pulses. The nonlinear nature of SPM makes arbitrary polynomial compensation necessary. Pre-compensation of SPM generated in an optical fiber by a 10 fs pulse reduced the pulse from 30fs to 20fs. We demonstrates adaptive correction with the wavefront MMDM by corrected for coma and astigmatism in a reflective multiphoton scanning microscope. An f1, parabola produces a very tight focus with no aberration when it is perfectly aligned. However, when beam scanning is used for two-dimensional imaging the image is severely aberrated. The MMDM and the GA are able to find the best possible wavefront for aberration correction for each scanning position. The horizontal scanning range was increased from 60 mum without the adaptive correction to 170 mum, ≈3 times the uncorrected scanning range, and the vertical scanning range was increased by a comparable amount. This resulted in an increase in scanning area of 9 times. The wavefront MMDM was also used for adaptive correction of spherical aberration from focusing from air, deep into a water-based sample. This depth-based aberration results from an index of refraction mismatch between the sample and the immersion medium of the objective and occurs regardless of beam scanning or sample scanning. By

  11. In vivo transcostal histotripsy therapy without aberration correction

    This study investigates the in vivo therapeutic capabilities of transcostal histotripsy without using aberration correction mechanisms and its thermal impact on overlying tissues. Non-invasive liver treatments were conducted in eight pigs, with four lesions generated through transcostal windows with full ribcage obstruction and four lesions created through transabdominal windows without rib coverage. Treatments were performed by a 750 kHz focused transducer using 5 cycle pulses at 200 Hz PRF, with estimated in situ peak negative pressures of 13–17 MPa. Temperatures on overlying tissues including the ribs were measured with needle thermocouples inserted superficially beneath the skin. Treatments of approximately 40 min were applied, allowing overlying tissue temperatures to reach saturation. Lesions yielded statistically comparable ablation volumes of 3.6 ± 1.7 cm3 and 4.5 ± 2.0 cm3 in transcostal and transabdominal treatments, respectively. The average temperature increase observed in transcostal treatments was 3.9 ± 2.1 °C, while transabdominal treatments showed an increase of 1.7 ± 1.3 °C. No damage was seen on the ribcage or other overlying tissues. These results indicate that histotripsy can achieve effective treatment through the ribcage in vivo without requiring correction mechanisms, while inducing no substantial thermal effects or damage to overlying tissues. Such capabilities could benefit several non-invasive therapy applications involving transcostal treatment windows. (paper)

  12. Proximity Scanning Transmission Electron Microscopy/Spectroscopy

    Hwang, Ing-Shouh

    2016-01-01

    Here a new microscopic method is proposed to image and characterize very thin samples like few-layer materials, organic molecules, and nanostructures with nanometer or sub-nanometer resolution using electron beams of energies lower than 20 eV. The microscopic technique achieves high resolution through the proximity (or near-field) effect, as in scanning tunneling microscopy (STM), while it also allows detection of transmitted electrons for imaging and spectroscopy, as in scanning transmission electron microscopy (STEM). This proximity transmission electron microscopy (PSTEM) does not require any lens to focus the electron beam. It also allows detailed characterization of the interaction of low-energy electron with materials. PSTEM can operate in a way very similar to scanning tunneling microscopy, which provides high-resolution imaging of geometric and electronic structures of the sample surface. In addition, it allows imaging and characterization of the interior structures of the sample based on the detected...

  13. Migration of Single Iridium Atoms and Tri-iridium Clusters on MgO Surfaces. Aberration-Corrected STEM Imaging and ab-initio Calculations

    Han, Chang W. [Purdue Univ., West Lafayette, IN (United States); Iddir, Hakim [Argonne National Lab. (ANL), Argonne, IL (United States); Uzun, Alper [Koc Univ., Instanbul (Turkey); Curtiss, Larry A. [Argonne National Lab. (ANL), Argonne, IL (United States); Browning, Nigel D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Gates, Bruce C. [Univ. of California, Davis, CA (United States); Ortalan, Volkan [Purdue Univ., West Lafayette, IN (United States)

    2015-11-06

    To address the challenge of fast, direct atomic-scale visualization of the diffusion of atoms and clusters on surfaces, we used aberration-corrected scanning transmission electron microscopy (STEM) with high scan speeds (as little as ~0.1 s per frame) to visualize the diffusion of (1) a heavy atom (Ir) on the surface of a support consisting of light atoms, MgO(100), and (2) an Ir3 cluster on MgO(110). Sequential Z-contrast images elucidate the diffusion mechanisms, including the hopping of Ir1 and the rotational migration of Ir3 as two Ir atoms remain anchored to the surface. Density functional theory (DFT) calculations provided estimates of the diffusion energy barriers and binding energies of the iridium species to the surfaces. The results show how the combination of fast-scan STEM and DFT calculations allow real-time visualization and fundamental understanding of surface diffusion phenomena pertaining to supported catalysts and other materials.

  14. Interfacial atomic structure analysis at sub-angstrom resolution using aberration-corrected STEM

    2014-01-01

    The atomic structure of a SiGe/Si epitaxial interface grown via molecular beam epitaxy on a single crystal silicon substrate was investigated using an aberration-corrected scanning transmittance electron microscope equipped with a high-angle annular dark-field detector and an energy-dispersive spectrometer. The accuracy required for compensation of the various residual aberration coefficients to achieve sub-angstrom resolution with the electron optics system was also evaluated. It was found that the interfacial layer was composed of a silicon single crystal, connected coherently to epitaxial SiGe nanolaminates. In addition, the distance between the dumbbell structures of the Si and Ge atoms was approximately 0.136 nm at the SiGe/Si interface in the [110] orientation. The corresponding fast Fourier transform exhibited a sub-angstrom scale point resolution of 0.78 Å. Furthermore, the relative positions of the atoms in the chemical composition line scan signals could be directly interpreted from the corresponding incoherent high-angle annular dark-field image. PMID:25426003

  15. Prospects for versatile phase manipulation in the TEM: Beyond aberration correction

    In this paper we explore the desirability of a transmission electron microscope in which the phase of the electron wave can be freely controlled. We discuss different existing methods to manipulate the phase of the electron wave and their limitations. We show how with the help of current techniques the electron wave can already be crafted into specific classes of waves each having their own peculiar properties. Assuming a versatile phase modulation device is feasible, we explore possible benefits and methods that could come into existence borrowing from light optics where the so-called spatial light modulators provide programmable phase plates for quite some time now. We demonstrate that a fully controllable phase plate building on Harald Rose's legacy in aberration correction and electron optics in general would open an exciting field of research and applications. - Highlights: • We offer a review of available phase manipulation techniques. • We demonstrate a method for producing Airy waves through aberration manipulation. • We outline hypothetical applications of arbitrary phase manipulation methods

  16. Prospects for versatile phase manipulation in the TEM: Beyond aberration correction

    Guzzinati, Giulio; Clark, Laura; Béché, Armand; Juchtmans, Roeland; Van Boxem, Ruben [EMAT, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp (Belgium); Mazilu, Michael [SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS (United Kingdom); Verbeeck, Jo, E-mail: jo.verbeeck@uantwerpen.be [EMAT, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp (Belgium)

    2015-04-15

    In this paper we explore the desirability of a transmission electron microscope in which the phase of the electron wave can be freely controlled. We discuss different existing methods to manipulate the phase of the electron wave and their limitations. We show how with the help of current techniques the electron wave can already be crafted into specific classes of waves each having their own peculiar properties. Assuming a versatile phase modulation device is feasible, we explore possible benefits and methods that could come into existence borrowing from light optics where the so-called spatial light modulators provide programmable phase plates for quite some time now. We demonstrate that a fully controllable phase plate building on Harald Rose's legacy in aberration correction and electron optics in general would open an exciting field of research and applications. - Highlights: • We offer a review of available phase manipulation techniques. • We demonstrate a method for producing Airy waves through aberration manipulation. • We outline hypothetical applications of arbitrary phase manipulation methods.

  17. Polyvinylidene fluoride molecules in nanofibers, imaged at atomic scale by aberration corrected electron microscopy.

    Lolla, Dinesh; Gorse, Joseph; Kisielowski, Christian; Miao, Jiayuan; Taylor, Philip L; Chase, George G; Reneker, Darrell H

    2016-01-01

    Atomic scale features of polyvinylidene fluoride molecules (PVDF) were observed with aberration corrected transmission electron microscopy. Thin, self-supporting PVDF nanofibers were used to create images that show conformations and relative locations of atoms in segments of polymer molecules, particularly segments near the surface of the nanofiber. Rows of CF2 atomic groups, at 0.25 nm intervals, which marked the paths of segments of the PVDF molecules, were seen. The fact that an electron microscope image of a segment of a PVDF molecule depended upon the particular azimuthal direction, along which the segment was viewed, enabled observation of twist around the molecular axis. The 0.2 nm side-by-side distance between the two fluorine atoms attached to the same carbon atom was clearly resolved. Morphological and chemical changes produced by energetic electrons, ranging from no change to fiber scission, over many orders of magnitude of electrons per unit area, promise quantitative new insights into radiation chemistry. Relative movements of segments of molecules were observed. Promising synergism between high resolution electron microscopy and molecular dynamic modeling was demonstrated. This paper is at the threshold of growing usefulness of electron microscopy to the science and engineering of polymer and other molecules. PMID:26369731

  18. Identifying different stacking sequences in few-layer CVD-grown Mo S2 by low-energy atomic-resolution scanning transmission electron microscopy

    Yan, Aiming; Chen, Wei; Ophus, Colin; Ciston, Jim; Lin, Yuyuan; Persson, Kristin; Zettl, Alex

    2016-01-01

    Atomically thin Mo S2 grown by chemical vapor deposition (CVD) is a promising candidate for next-generation electronics due to inherent CVD scalability and controllability. However, it is well known that the stacking sequence in few-layer Mo S2 can significantly impact electrical and optical properties. Herein we report different intrinsic stacking sequences in CVD-grown few-layer Mo S2 obtained by atomic-resolution annular-dark-field imaging in an aberration-corrected scanning transmission electron microscope operated at 50 keV. Trilayer Mo S2 displays a new stacking sequence distinct from the commonly observed 2 H and 3 R phases of Mo S2 . Density functional theory is used to examine the stability of different stacking sequences, and the findings are consistent with our experimental observations.

  19. Scanning transmission ion microscopy of polycarbonate nanocapillaries

    Complete text of publication follows. Nanochanneled materials are of a great interest due to their peculiar properties and high potential impact for the fabrication of nanostructures and nanodevices. Polycarbonate membranes are produced by heavy ion irradiation followed by chemical etching of the ion tracks. The irradiation parameters determine the porosity (areal density of the capillaries) and angular spread, while the channel diameters and shapes depend on the chemical process parameters. Such polycarbonate (and other materials) membranes are commercially available from a few manufacturers. The primary use of the filters involves packaging and filtering applications. Moreover, they are used for collecting atmospheric aerosols for environmental research. The nanocapillaries formed in membranes are particularly suitable for ion and electron guiding studies of a recently discovered, but not yet completely understood capillary guiding phenomenon. This interesting guiding effect is very promising for patterning by parallel writing with ions and/or electrons through masks. In order to get a better understanding of this phenomenon, we need a better characterization of the capillaries themselves. This study is addressing the angular distribution of the nanochannels in the polycarbonate filters by using a nuclear microprobe facility and the method of scanning transmission ion microscopy (STIM). The STIM experiments in this work have been performed at ATOMKI. The proton energy was 2 MeV, the beam intensity was about 1000 protons s-1, the beam spot size was about 1 x 1 μm, the scan size was 100 x 100 μm and the beam divergence was smaller than 0.07 deg. A scanning electron microscope (SEM, Hitachi S4300 CFE) was used to measure the capillary diameters and the membrane porosity. The sample thickness was determined by a profilometer (AMBIOS XP-I). We have investigated two different pieces of Millipore IsoporeTM samples. A typical SEM image showed several overlapping holes

  20. Transcranial phase aberration correction using beam simulations and MR-ARFI

    Purpose: Transcranial magnetic resonance-guided focused ultrasound surgery is a noninvasive technique for causing selective tissue necrosis. Variations in density, thickness, and shape of the skull cause aberrations in the location and shape of the focal zone. In this paper, the authors propose a hybrid simulation-MR-ARFI technique to achieve aberration correction for transcranial MR-guided focused ultrasound surgery. The technique uses ultrasound beam propagation simulations with MR Acoustic Radiation Force Imaging (MR-ARFI) to correct skull-caused phase aberrations. Methods: Skull-based numerical aberrations were obtained from a MR-guided focused ultrasound patient treatment and were added to all elements of the InSightec conformal bone focused ultrasound surgery transducer during transmission. In the first experiment, the 1024 aberrations derived from a human skull were condensed into 16 aberrations by averaging over the transducer area of 64 elements. In the second experiment, all 1024 aberrations were applied to the transducer. The aberrated MR-ARFI images were used in the hybrid simulation-MR-ARFI technique to find 16 estimated aberrations. These estimated aberrations were subtracted from the original aberrations to result in the corrected images. Each aberration experiment (16-aberration and 1024-aberration) was repeated three times. Results: The corrected MR-ARFI image was compared to the aberrated image and the ideal image (image with zero aberrations) for each experiment. The hybrid simulation-MR-ARFI technique resulted in an average increase in focal MR-ARFI phase of 44% for the 16-aberration case and 52% for the 1024-aberration case, and recovered 83% and 39% of the ideal MR-ARFI phase for the 16-aberrations and 1024-aberration case, respectively. Conclusions: Using one MR-ARFI image and noa priori information about the applied phase aberrations, the hybrid simulation-MR-ARFI technique improved the maximum MR-ARFI phase of the beam's focus

  1. Transcranial phase aberration correction using beam simulations and MR-ARFI

    Vyas, Urvi, E-mail: urvi.vyas@gmail.com; Kaye, Elena; Pauly, Kim Butts [Department of Radiology, Stanford University, Stanford, California 94305 (United States)

    2014-03-15

    Purpose: Transcranial magnetic resonance-guided focused ultrasound surgery is a noninvasive technique for causing selective tissue necrosis. Variations in density, thickness, and shape of the skull cause aberrations in the location and shape of the focal zone. In this paper, the authors propose a hybrid simulation-MR-ARFI technique to achieve aberration correction for transcranial MR-guided focused ultrasound surgery. The technique uses ultrasound beam propagation simulations with MR Acoustic Radiation Force Imaging (MR-ARFI) to correct skull-caused phase aberrations. Methods: Skull-based numerical aberrations were obtained from a MR-guided focused ultrasound patient treatment and were added to all elements of the InSightec conformal bone focused ultrasound surgery transducer during transmission. In the first experiment, the 1024 aberrations derived from a human skull were condensed into 16 aberrations by averaging over the transducer area of 64 elements. In the second experiment, all 1024 aberrations were applied to the transducer. The aberrated MR-ARFI images were used in the hybrid simulation-MR-ARFI technique to find 16 estimated aberrations. These estimated aberrations were subtracted from the original aberrations to result in the corrected images. Each aberration experiment (16-aberration and 1024-aberration) was repeated three times. Results: The corrected MR-ARFI image was compared to the aberrated image and the ideal image (image with zero aberrations) for each experiment. The hybrid simulation-MR-ARFI technique resulted in an average increase in focal MR-ARFI phase of 44% for the 16-aberration case and 52% for the 1024-aberration case, and recovered 83% and 39% of the ideal MR-ARFI phase for the 16-aberrations and 1024-aberration case, respectively. Conclusions: Using one MR-ARFI image and noa priori information about the applied phase aberrations, the hybrid simulation-MR-ARFI technique improved the maximum MR-ARFI phase of the beam's focus.

  2. Depth-resolution imaging of crystalline nanoclusters attached on and embedded in amorphous films using aberration-corrected TEM

    Yamasaki, Jun, E-mail: yamasaki@uhvem.osaka-u.ac.jp [Research Center for Ultra-High Voltage Electron Microscopy, Osaka University, 7-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); EcoTopia Science Institute, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Mori, Masayuki [Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Hirata, Akihiko [Advanced Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Hirotsu, Yoshihiko [Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Tanaka, Nobuo [EcoTopia Science Institute, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan)

    2015-04-15

    For observations of crystalline nanoclusters, the features and capabilities of depth-resolution imaging by aberration-corrected transmission electron microscopy (TEM) were investigated using image simulations and experiments for two types of samples. The first sample was gold clusters attached on an amorphous carbon film. The experimental through-focal series indicated that the focal plane for the cluster was shifted 3 nm from that for the supporting film. This difference is due to the depth-resolution imaging of the cluster and film, the mid-planes of which are separated by 3 nm along the depth direction (the electron incident direction). On the basis of this information, the three-dimensional configuration of the sample, such as the film thickness of 2 nm, was successfully illustrated. The second sample was a Zr{sub 66.7}Ni{sub 33.3} metallic glass including a medium-range-order (MRO) structure, which was approximately considered to be a crystalline cluster with a diameter of 1.6 nm. In the experimental through-focal series, the lattice fringe of the MRO cluster was visible at limited focal conditions. Image simulations reproduced well the focal conditions and also indicated a structural condition for the visualization that the embedded cluster must be apart from the mid-plane of the matrix film. Similar to the case of the first sample, this result can be explained by the idea that the “effective focal planes” for the film and cluster are at different heights. This type of depth-resolution phase contrast imaging is possible only in aberration-corrected TEM and when the sample has a simple structure and is sufficiently thin for the kinematical scattering approximation. - Highlights: • Depth-resolution imaging by aberration-corrected TEM was demonstrated. • Thickness of a carbon film supporting gold nano-crystals was successfully estimated. • A crystalline nanocluster embedded in an amorphous matrix was successfully observed. • It was clarified that

  3. Depth-resolution imaging of crystalline nanoclusters attached on and embedded in amorphous films using aberration-corrected TEM

    For observations of crystalline nanoclusters, the features and capabilities of depth-resolution imaging by aberration-corrected transmission electron microscopy (TEM) were investigated using image simulations and experiments for two types of samples. The first sample was gold clusters attached on an amorphous carbon film. The experimental through-focal series indicated that the focal plane for the cluster was shifted 3 nm from that for the supporting film. This difference is due to the depth-resolution imaging of the cluster and film, the mid-planes of which are separated by 3 nm along the depth direction (the electron incident direction). On the basis of this information, the three-dimensional configuration of the sample, such as the film thickness of 2 nm, was successfully illustrated. The second sample was a Zr66.7Ni33.3 metallic glass including a medium-range-order (MRO) structure, which was approximately considered to be a crystalline cluster with a diameter of 1.6 nm. In the experimental through-focal series, the lattice fringe of the MRO cluster was visible at limited focal conditions. Image simulations reproduced well the focal conditions and also indicated a structural condition for the visualization that the embedded cluster must be apart from the mid-plane of the matrix film. Similar to the case of the first sample, this result can be explained by the idea that the “effective focal planes” for the film and cluster are at different heights. This type of depth-resolution phase contrast imaging is possible only in aberration-corrected TEM and when the sample has a simple structure and is sufficiently thin for the kinematical scattering approximation. - Highlights: • Depth-resolution imaging by aberration-corrected TEM was demonstrated. • Thickness of a carbon film supporting gold nano-crystals was successfully estimated. • A crystalline nanocluster embedded in an amorphous matrix was successfully observed. • It was clarified that only clusters

  4. Imaging individual lanthanum atoms in zeolite Y by scanning transmission electron microscopy: evidence of lanthanum pair sites

    Xu, Pinghong; Lu, Jing; Aydin, C.; Debefve, Louise M.; Browning, Nigel D.; Chen, Cong-Yan; Gates, Bruce C.

    2015-09-01

    Images of La-exchanged NaY zeolite obtained with aberration-corrected scanning transmission electron microscopy (STEM) show that about 80% of the La cations were present as site-isolated species, with the remainder in pair sites. The distance between La cations in the pair sites ranged from 1.44 to 3.84 Å, consistent with the presence of pairs of cations tilted at various angles with respect to the support surface. The actual distance between La cations in the pair sites is inferred to be approximately 3.84 Å, which is shorter than the distance between the nearest Al sites in the zeolite (4.31 Å). The results therefore suggest the presence of dimeric structures of La cations bridged with OH groups, and the presence of such species has been inferred previously on the basis of X-ray photoelectron spectroscopy (W. Grünert, U. Sauerlandt, R. Schlögl, H.G. Karge, J. Phys. Chem., 97 (1993) 1413).

  5. Scanning transmission low energy electron microscopy

    Müllerová, Ilona; Hovorka, Miloš; Frank, Luděk

    New York : IBM T.J. Watson Research Center, 2010. s. 25. [LEEM/PEEM /7./. 08.08.2010-13.08.2010, New York] R&D Projects: GA AV ČR IAA100650902 Institutional research plan: CEZ:AV0Z20650511 Keywords : scanning electron microscope * he low energy electron microscope * graphene Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  6. In-situ aberration correction of Bessel beams using spatial light modulator

    Jákl, Petr; Arzola, A. V.; Zemánek, Pavel

    Bellingham: SPIE, 2014, 94420G: 1-5. ISBN 9781628415575. ISSN 0277-786X. [Optics and Measurement Conference 2014 (OaM 2014). Liberec (CZ), 07.10.2014-10.10.2014] R&D Projects: GA MŠk LH12018; GA MŠk(CZ) LO1212; GA MŠk ED0017/01/01 Institutional support: RVO:68081731 Keywords : optical aberration correction * holography * spatial light modulator * optical trapping Subject RIV: BH - Optics, Masers, Lasers

  7. Nanochannel alignment analysis by scanning transmission ion microscopy

    Rajta, I.; Gál, G.A.B.; Szilasi, S.Z.;

    2010-01-01

    In this paper a study on the ion transmission ratio of a nanoporous alumina sample is presented. The sample was investigated by scanning transmission ion microscopy (STIM) with different beam sizes. The hexagonally close-packed AlO nanocapillary array, realized as a suspended membrane of 15 νm...

  8. Scanning Transmission X-Ray, Laser Scanning, and Transmission Electron Microscopy Mapping of the Exopolymeric Matrix of Microbial Biofilms

    Lawrence, J R; Swerhone, G. D. W.; Leppard, G. G.; Araki, T; Zhang, X.; West, M. M.; Hitchcock, A. P.

    2003-01-01

    Confocal laser scanning microscopy (CLSM), transmission electron microscopy (TEM), and soft X-ray scanning transmission X-ray microscopy (STXM) were used to map the distribution of macromolecular subcomponents (e.g., polysaccharides, proteins, lipids, and nucleic acids) of biofilm cells and matrix. The biofilms were developed from river water supplemented with methanol, and although they comprised a complex microbial community, the biofilms were dominated by heterotrophic bacteria. TEM provid...

  9. Derivative Form of Off-axis Aberration Correction Surface and Its Application in Solar Energy Concentration

    LI Li; CHEN Ying-Tian; HU Sen

    2009-01-01

    By using the derivative method, we obtained the same result with that of the previous work of Chen et al.in 2006.Different from the integral form, the derivative form of the surface expression published in this paper is derived from differential equation and based on the theory of non-imaging focusing heliostat proposed by Chen et al.in 2001.The comparison of the derivative form of fixed aberration correction surface has been made with that of integral form surface as well as that of spherical surface in concentrating the solar ray.

  10. Conformal optical design with combination of static and dynamic aberration corrections

    Li Yan; Li Lin; Huang Yi-Fan; Liu Jia-Guo

    2009-01-01

    Conformal domes that are shaped to meet aerodynamic requirements can increase range and speed for the host platform. Because these domes typically deviate greatly from spherical surface descriptions, a variety of aberrations are induced which vary with the field-of-regard (FOR) angle. A system for correcting optical aberrations created by a conformal dome has an outer surface and an inner surface. Optimizing the inner surface is regard as static aberration correction. A deformable mirror is placed at the position of the secondary mirror in the two-mirror all reflective imaging system, which is the dynamic aberration correction. An ellipsoidal MgF2 conformal dome with a fineness ratio of 1.0 is designed as an example. The FOR angle is 00°-30°, and the design wavelength is 4 μm. After the optimization at 7zoom positions by using the design tools Code V, the root-mean-square (RMS) spot size is reduced to approximately 0.99 to 1.48 times the diffraction limit. The design results show that the performances of the conformal optical systems can be greatly improved by the combination of the static correction and the dynamic correction.

  11. Correlation of structure and mass via scanning transmission electron microscopy

    Tacke, S.; Krzyžánek, Vladislav; Reichelt, R.; Klingauf, J.

    Vol. 2. Regensburg: University of Regensburg, 2013, s. 310-311. [Microscopy Conference 2013. Regensburg (DE), 25.08.2013-30. 08.2013] R&D Projects: GA MŠk EE.2.3.20.0103 Institutional support: RVO:68081731 Keywords : quantitative scanning transmission electron microscopy * mass measurement Subject RIV: BH - Optics, Masers, Lasers

  12. Development of a compact scanning transmission X-Ray microscope

    We report a compact scanning transmission X-ray microscope newly designed and developed at the Photon Factory. The microscope has very compact size and is equipped with fully digitized control electronics to realize high stability, precise positioning and fast data acquisition. The hardware design of the microscope is described in detail. Results of measurement using test samples are also presented.

  13. Novel approach to stationary transmission scanning using Compton scattered radiation

    Transmission scanning-based estimation of the attenuation map plays a crucial role in quantitative radionuclide imaging. X-ray computed tomography (CT) reconstructs directly the attenuation coefficients map from data transmitted through the object. This paper proposes an alternative route for reconstructing the object attenuation map by exploiting Compton scatter of transmitted radiation from an externally placed radionuclide source. In contrast to conventional procedures, data acquisition is realized as a series of images parameterized by the Compton scattering angle and registered on a stationary gamma camera operating without spatial displacement. Numerical simulation results using realistic voxel-based phantoms are presented to illustrate the efficiency of this new transmission scanning approach for attenuation map reconstruction. The encouraging results presented in this paper may suggest the possibility of proposing a new concept for emission/transmission imaging using scattered radiation, which has many advantages compared to conventional technologies

  14. Adaptive, spatially-varying aberration correction for real-time holographic projectors.

    Kaczorowski, Andrzej; Gordon, George S D; Wilkinson, Timothy D

    2016-07-11

    A method of generating an aberration- and distortion-free wide-angle holographically projected image in real time is presented. The target projector is first calibrated using an automated adaptive-optical mechanism. The calibration parameters are then fed into the hologram generation program, which applies a novel piece-wise aberration correction algorithm. The method is found to offer hologram generation times up to three orders of magnitude faster than the standard method. A projection of an aberration- and distortion-free image with a field of view of 90x45 degrees is demonstrated. The implementation on a mid-range GPU achieves high resolution at a frame rate up to 12fps. The presented methods are automated and can be performed on any holographic projector. PMID:27410846

  15. Progress on PEEM3 - An Aberration Corrected X-Ray Photoemission Electron Microscope at the ALS

    A new ultrahigh-resolution photoemission electron microscope called PEEM3 is being developed and built at the Advanced Light Source (ALS). An electron mirror combined with a much-simplified magnetic dipole separator is to be used to provide simultaneous correction of spherical and chromatic aberrations. It is installed on an elliptically polarized undulator (EPU) beamline, and will be operated with very high spatial resolution and high flux to study the composition, structure, electric and magnetic properties of complex materials. The instrument has been designed and is described. The instrumental hardware is being deployed in 2 phases. The first phase is the deployment of a standard PEEM type microscope consisting of the standard linear array of electrostatic electron lenses. The second phase will be the installation of the aberration corrected upgrade to improve resolution and throughput. This paper describes progress as the instrument enters the commissioning part of the first phase

  16. Progress on PEEM3 -- An Aberration Corrected X-Ray Photoemission Electron Microscope at the ALS

    A new ultrahigh-resolution photoemission electron microscope called PEEM3 is being developed and built at the Advanced Light Source (ALS). An electron mirror combined with a much-simplified magnetic dipole separator is to be used to provide simultaneous correction of spherical and chromatic aberrations. It is installed on an elliptically polarized undulator (EPU) beamline, and will be operated with very high spatial resolution and high flux to study the composition, structure, electric and magnetic properties of complex materials. The instrument has been designed and is described. The instrumental hardware is being deployed in 2 phases. The first phase is the deployment of a standard PEEM type microscope consisting of the standard linear array of electrostatic electron lenses. The second phase will be the installation of the aberration corrected upgrade to improve resolution and throughput. This paper describes progress as the instrument enters the commissioning part of the first phase

  17. Simultaneous emission and transmission scanning in positron emission tomography

    Examination by PET (positron emission tomography) scanning, following the dosage of 2-deoxy-18F fluoro-D-glucose (FDG), is positively utilized for the diagnosis of cancers, rather than for the purpose of studies. This is because the examination by FDG-PET (PET scanning following the dosage of FDG) ensures higher efficiency in discrimination of cancers, than conventional CT and PET. The method of whole body scanning by PET scanning following the dosage of FDG is effectively utilized not only for discrimination cancers, but also for determining the degree of malignancy of tumors and evaluating the methods of treatment of cancers. In conventional methods for examining the degree of malignancy of tumors and evaluating the methods of cancer treatment, it is necessary to correct for the gamma-ray attenuation, which requires a longer time for examination, increasing the physical and psychological pains of the patients. We have installed the simultaneous emission and transmission scanning capability into the HEADTOME-V of the Shimadzu SET-2000W Series positron emission tomographic scanning instruments, to establish an instrument that permits FDG-PET whole body scanning in actual clinical fields, with minimized physical and psychological pains of patients concerned, yet ensuring an outstandingly high examination efficiency. This report also presents some data obtained by this newly developed instrument and those obtained in practical applications. (author)

  18. Nanomaterial datasets to advance tomography in scanning transmission electron microscopy

    Levin, Barnaby D.A.; Padgett, Elliot; Chen, Chien-Chun; Scott, M C; Xu, Rui; Theis, Wolfgang; Jiang, Yi; Yang, Yongsoo; Ophus, Colin; Zhang, Haitao; Ha, Don-Hyung; Wang, Deli; Yu, Yingchao; Abruña, Hector D.; Richard D Robinson

    2016-01-01

    Electron tomography in materials science has flourished with the demand to characterize nanoscale materials in three dimensions (3D). Access to experimental data is vital for developing and validating reconstruction methods that improve resolution and reduce radiation dose requirements. This work presents five high-quality scanning transmission electron microscope (STEM) tomography datasets in order to address the critical need for open access data in this field. The datasets represent the cu...

  19. Optical transmission scanning for damage quantification in impacted GFRP composites

    Khomenko, Anton; Karpenko, Oleksii; Koricho, Ermias G.; Haq, Mahmoodul; Cloud, Gary L.; Udpa, Lalita

    2016-04-01

    Glass fiber reinforced polymer (GFRP) composites constitute nearly 90% of the global composites market and are extensively used in aerospace, marine, automotive and construction industries. While their advantages of lightweight and superior mechanical properties are well explored, non-destructive evaluation (NDE) techniques that allow for damage/defect detection and assessment of its extent and severity are not fully developed. Some of the conventional NDE techniques for GFRPs include ultrasonics, X-ray, IR thermography, and a variety of optical techniques. Optical methods, specifically measuring the transmission properties (e.g. ballistic optical imaging) of specimens, provide noninvasive, safe, inexpensive, and compact solutions and are commonly used in biomedical applications. In this work, this technique is adapted for rapid NDE of GFRP composites. In its basic form, the system for optical transmission scanning (OTS) consists of a light source (laser diode), a photo detector and a 2D translation stage. The proposed technique provides high-resolution, rapid and non-contact OT (optical transmittance)-scans, and does not require any coupling. The OTS system was used for inspection of pristine and low-velocity impacted (damaged) GFRP samples. The OT-scans were compared with conventional ultrasonic C-scans and showed excellent agreement but with better resolution. Overall, the work presented lays the groundwork for cost-effective, non-contact, and rapid NDE of GFRP composite structures.

  20. Attenuation correction without transmission scan for the MAMMI breast PET

    Whole-body Positron Emission Tomography (PET) scanners are required in order to span large Fields of View (FOV). Therefore, reaching the sensitivity and spatial resolution required for early stage breast tumor detection is not straightforward. MAMMI is a dedicated breast PET scanner with a ring geometry designed to provide PET images with a spatial resolution as high as 1.5 mm, being able to detect small breast tumors (<1cm). The patient lays down in prone position during the scan, thus making possible to image the whole breast, up to regions close to the base of the pectoral without the requirement of breast compression. Attenuation correction (AC) for PET data improves the image quality and the quantitative accuracy of radioactivity distribution determination. In dedicated, high resolution breast cancer scanners, this correction would enhance the proper diagnosis in early disease stages. In whole-body PET scanners, AC is usually taken into account with the use of transmission scans, either by external radioactive rod sources or by Computed Tomography (CT). This considerably increases the radiation dose administered to the patient and time needed for the exploration. In this work we propose a method for breast shape identification by means of PET image segmentation. The breast shape identification will be used for the determination of the AC. For the case of a specific breast PET scanner the procedure we propose should provide AC similar to that obtained by transmission scans as we take advantage of the breast anatomical simplicity. Experimental validation of the proposed approach with a dedicated breast PET prototype is also presented. The main advantage of this method is an important dose reduction since the transmission scan is not required.

  1. Nanostructural and Chemical Characterization of Supported Metal Oxide Catalysts by Aberration Corrected Analytical Electron Microscopy

    Zhou, Wu

    In this thesis, aberration corrected STEM imaging and chemical analysis techniques have been extensively applied in the structural and chemical characterization of supported tungsten oxide catalysts in an attempt to reveal the structure-activity relationships at play in these catalyst systems. The supported WO3/ZrO2 solid acid catalyst system is a major focal point of this thesis, and detailed aberration-corrected STEM-HAADF imaging studies were performed on a systematic set of catalysts showing different level of catalytic performance. The nature of the catalytically most active WOx species was identified by correlating structural information, obtained from STEM-HAADF and in-situ optical spectroscopy studies, with catalytic testing results. Specifically, ˜1nm distorted Zr-WOx mixed oxide clusters were identified to be the most active species for both the methanol dehydration and n-pentane isomerization reactions in the WO3/ZrO2 catalyst system. The use of amorphous zirconia as a precursor support material makes it much easier to extract and incorporate Zr cations into the surface WOx clusters during calcination. The calcination temperature was also identified to also play an important role in the formation of these most active Zr-WOx clusters. When the calcination temperature is comparable to or higher than the 896K Huttig temperature of ZrO2 (at which surface ZrO x species have sufficient mobility to agglomerate and sinter), the chance for successful surface WOx and ZrOx intermixing is significantly increased. Based on this perceived structure-activity relationship, several new catalyst synthesis strategies were developed in an attempt to optimize the catalytic performance of WOx-based catalysts. We have demonstrated in Chapter 3 that co-impregnation of WOx and ZrOx precursors onto an inactive model WO3/ZrO2 catalyst, followed by a calcination treatment above the 896K Huttig temperature of ZrO 2, promotes the surface diffusion of ZrO2 and intermixing of Zr

  2. A monochromatic, aberration-corrected, dual-beam low energy electron microscope

    The monochromatic, aberration-corrected, dual-beam low energy electron microscope (MAD-LEEM) is a novel instrument aimed at imaging of nanostructures and surfaces at sub-nanometer resolution that includes a monochromator, aberration corrector and dual beam illumination. The monochromator reduces the energy spread of the illuminating electron beam, which significantly improves spectroscopic and spatial resolution. The aberration corrector utilizes an electron mirror with negative aberrations that can be used to compensate the aberrations of the LEEM objective lens for a range of electron energies. Dual flood illumination eliminates charging generated when a conventional LEEM is used to image insulating specimens. MAD-LEEM is designed for the purpose of imaging biological and insulating specimens, which are difficult to image with conventional LEEM, Low-Voltage SEM, and TEM instruments. The MAD-LEEM instrument can also be used as a general purpose LEEM with significantly improved resolution. The low impact energy of the electrons is critical for avoiding beam damage, as high energy electrons with keV kinetic energies used in SEMs and TEMs cause irreversible change to many specimens, in particular biological materials. A potential application for MAD-LEEM is in DNA sequencing, which demands imaging techniques that enable DNA sequencing at high resolution and speed, and at low cost. The key advantages of the MAD-LEEM approach for this application are the low electron impact energies, the long read lengths, and the absence of heavy-atom DNA labeling. Image contrast simulations of the detectability of individual nucleotides in a DNA strand have been developed in order to refine the optics blur and DNA base contrast requirements for this application. - Highlights: • We present a LEEM with a monochromator, aberration corrector, and two electron beams. • We analyze objective lens aberrations up to 5th order with aberration correction. • Tetrode and pentode mirror

  3. A computer program for scanning transmission ion microscopy simulation

    Wu, R.; Shen, H.; Mi, Y.; Sun, M. D.; Yang, M. J.

    2005-04-01

    With the installation of the Scanning Proton Microprobe system at Fudan University, we are in the process of developing a three-dimension reconstruction technique based on scanning transmission ion microscopy-computed tomography (STIM-CT). As the first step, a related computer program of STIM simulation has been established. This program is written in the Visual C++®, using the technique of OOP (Object Oriented Programming) and it is a standard multiple-document Windows® program. It can be run with all MS Windows® operating systems. The operating mode is the menu mode, using a multiple process technique. The stopping power theory is based on the Bethe-Bloch formula. In order to simplify the calculation, the improved cylindrical coordinate model was introduced in the program instead of a usual spherical or cylindrical coordinate model. The simulated results of a sample at several rotation angles are presented.

  4. Transmission through thin films by low energy scanning electron microscopy

    Müllerová, Ilona; Hovorka, Miloš; Sobota, Jaroslav; Hanzlíková, Renáta; Fořt, Tomáš; Frank, Luděk

    Graz : Verlag der Technischen Universität, 2009, Vol. 1: 163-164. ISBN 978-3-85125-062-6. [MC 2009 - Joint Meeting of Dreiländertagung and Multinational Congress on Microscopy /9./. Graz (AT), 30.08.2009-04.09.2009] R&D Projects: GA AV ČR IAA100650902 Institutional research plan: CEZ:AV0Z20650511 Keywords : low energy electrons * thin fílms * scanning transmission elektron microscopy Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering http://www.univie.ac.at/asem/Graz_MC_09/papers/95398.pdf

  5. Free-standing graphene by scanning transmission electron microscopy

    Free-standing graphene sheets have been imaged by scanning transmission electron microscopy (STEM). We show that the discrete numbers of graphene layers enable an accurate calibration of STEM intensity to be performed over an extended thickness and with single atomic layer sensitivity. We have applied this calibration to carbon nanoparticles with complex structures. This leads to the direct and accurate measurement of the electron mean free path. Here, we demonstrate potentials using graphene sheets as a novel mass standard in STEM-based mass spectrometry.

  6. Double aberration-corrected TEM/STEM of tungstated zirconia nanocatalysts for the synthesis of paracetamol

    Yoshida, K; Boyes, E D; Gai, P L [York JEOL Nanocentre (United Kingdom); Shiju, N R; Brown, D R, E-mail: pgb500@york.ac.u [Department of Chemical and Biological Sciences, University of Huddersfield, Huddersfield, HD1 3DH (United Kingdom)

    2010-07-01

    We report highly active tungstated zirconia nanocatalysts for the synthesis of paracetamol by Beckmann rearrangement of 4-hydroxyacetophenone oxime. Double aberration-corrected (2AC)-TEM/STEM studies were performed in a JEOL 2200FS FEG TEM/STEM at the 1 Angstrom (1 A = 0.1 nanometer) level. Observations at close to zero defocus were carried out using the AC-TEM as well as AC-STEM including high angle annular dark field (HAADF) imaging, from the same areas of the catalyst crystallites. The studies from the same areas have revealed the location and the nanostructure of the polytungstate species (clusters) and the nanograins of zirconia. The AC (S)TEM was crucial to observe the nanostructure and location of polytungstate clusters on the zirconia grains. Polytungstate clusters as small as 0.5 nm have been identified using the HAADF-STEM. The nanostructures of the catalyst and the W surface density have been correlated with paracetamol reaction studies. The results demonstrate the nature of active sites and high activity of the tungstated zirconia nanocatalyst, which is an environmentally clean alternative to the current homogeneous process.

  7. Double aberration-corrected TEM/STEM of tungstated zirconia nanocatalysts for the synthesis of paracetamol

    Yoshida, K.; Shiju, N. R.; Brown, D. R.; Boyes, E. D.; Gai, P. L.

    2010-07-01

    We report highly active tungstated zirconia nanocatalysts for the synthesis of paracetamol by Beckmann rearrangement of 4-hydroxyacetophenone oxime. Double aberration-corrected (2AC)-TEM/STEM studies were performed in a JEOL 2200FS FEG TEM/STEM at the 1 Angstrom (1 Å = 0.1 nanometer) level. Observations at close to zero defocus were carried out using the AC-TEM as well as AC-STEM including high angle annular dark field (HAADF) imaging, from the same areas of the catalyst crystallites. The studies from the same areas have revealed the location and the nanostructure of the polytungstate species (clusters) and the nanograins of zirconia. The AC (S)TEM was crucial to observe the nanostructure and location of polytungstate clusters on the zirconia grains. Polytungstate clusters as small as 0.5 nm have been identified using the HAADF-STEM. The nanostructures of the catalyst and the W surface density have been correlated with paracetamol reaction studies. The results demonstrate the nature of active sites and high activity of the tungstated zirconia nanocatalyst, which is an environmentally clean alternative to the current homogeneous process.

  8. Double aberration-corrected TEM/STEM of tungstated zirconia nanocatalysts for the synthesis of paracetamol

    We report highly active tungstated zirconia nanocatalysts for the synthesis of paracetamol by Beckmann rearrangement of 4-hydroxyacetophenone oxime. Double aberration-corrected (2AC)-TEM/STEM studies were performed in a JEOL 2200FS FEG TEM/STEM at the 1 Angstrom (1 A = 0.1 nanometer) level. Observations at close to zero defocus were carried out using the AC-TEM as well as AC-STEM including high angle annular dark field (HAADF) imaging, from the same areas of the catalyst crystallites. The studies from the same areas have revealed the location and the nanostructure of the polytungstate species (clusters) and the nanograins of zirconia. The AC (S)TEM was crucial to observe the nanostructure and location of polytungstate clusters on the zirconia grains. Polytungstate clusters as small as 0.5 nm have been identified using the HAADF-STEM. The nanostructures of the catalyst and the W surface density have been correlated with paracetamol reaction studies. The results demonstrate the nature of active sites and high activity of the tungstated zirconia nanocatalyst, which is an environmentally clean alternative to the current homogeneous process.

  9. A Bloch wave analysis of optical sectioning in aberration-corrected STEM

    The reduction in the focal depth of field that occurs through the use of larger apertures in aberration-corrected STEM allows three-dimensional information to be retrieved by optical depth sectioning. This paper explores depth sectioning in zone-axis crystals using Bloch wave calculations. By decomposing the calculation into the contribution from individual states and from individual partial plane waves in the convergent cone of illumination, we explain the form of the electron intensity in the crystal as a function of depth. Two separate effects are found that can cause the intensity maximum to deviate from that of the expected defocus value. Firstly it is found that the unbound, high angle excited states give rise to a behaviour similar to that of the probe focusing in the vacuum, but with a prefocusing effect due to the lensing effect of the potential of the atomic column. Superimposed upon this prefocused peak is an oscillation due to interference between the channelling 1s state and the rest of the wavefunction. This oscillation can actually prevent an intensity maximum being formed at certain depths in the crystal, and will complicate the interpretation of optical sectioning data

  10. A broadband toolbox for scanning microwave microscopy transmission measurements

    Lucibello, Andrea; Sardi, Giovanni Maria; Capoccia, Giovanni; Proietti, Emanuela; Marcelli, Romolo; Kasper, Manuel; Gramse, Georg; Kienberger, Ferry

    2016-05-01

    In this paper, we present in detail the design, both electromagnetic and mechanical, the fabrication, and the test of the first prototype of a Scanning Microwave Microscope (SMM) suitable for a two-port transmission measurement, recording, and processing the high frequency transmission scattering parameter S21 passing through the investigated sample. The S21 toolbox is composed by a microwave emitter, placed below the sample, which excites an electromagnetic wave passing through the sample under test, and is collected by the cantilever used as the detector, electrically matched for high frequency measurements. This prototype enhances the actual capability of the instrument for a sub-surface imaging at the nanoscale. Moreover, it allows the study of the electromagnetic properties of the material under test obtained through the measurement of the reflection (S11) and transmission (S21) parameters at the same time. The SMM operates between 1 GHz and 20 GHz, current limit for the microwave matching of the cantilever, and the high frequency signal is recorded by means of a two-port Vector Network Analyzer, using both contact and no-contact modes of operation, the latter, especially minded for a fully nondestructive and topography-free characterization. This tool is an upgrade of the already established setup for the reflection mode S11 measurement. Actually, the proposed setup is able to give richer information in terms of scattering parameters, including amplitude and phase measurements, by means of the two-port arrangement.

  11. Imaging screw dislocations at atomic resolution by aberration-corrected electron optical sectioning

    Yang, H.; Lozano, J. G.; Pennycook, T. J.; Jones, L.; Hirsch, P. B.; Nellist, P. D.

    2015-06-01

    Screw dislocations play an important role in materials' mechanical, electrical and optical properties. However, imaging the atomic displacements in screw dislocations remains challenging. Although advanced electron microscopy techniques have allowed atomic-scale characterization of edge dislocations from the conventional end-on view, for screw dislocations, the atoms are predominantly displaced parallel to the dislocation line, and therefore the screw displacements are parallel to the electron beam and become invisible when viewed end-on. Here we show that screw displacements can be imaged directly with the dislocation lying in a plane transverse to the electron beam by optical sectioning using annular dark field imaging in a scanning transmission electron microscope. Applying this technique to a mixed [a+c] dislocation in GaN allows direct imaging of a screw dissociation with a 1.65-nm dissociation distance, thereby demonstrating a new method for characterizing dislocation core structures.

  12. Optimization and stability of the contrast transfer function in aberration-corrected electron microscopy

    Tromp, R.M., E-mail: rtromp@us.ibm.com [IBM T.J. Watson Research Center, 1101 Kitchawan Road, Yorktown Heights, NY 10598 (United States); Leiden Institute of Physics, Kamerlingh Onnes Laboratory, Niels Bohrweg 2, 2333 CA Leiden (Netherlands); Schramm, S.M. [Leiden Institute of Physics, Kamerlingh Onnes Laboratory, Niels Bohrweg 2, 2333 CA Leiden (Netherlands)

    2013-02-15

    The Contrast Transfer Function (CTF) describes the manner in which the electron microscope modifies the object exit wave function as a result of objective lens aberrations. For optimum resolution in C{sub 3}-corrected microscopes it is well established that a small negative value of C{sub 3}, offset by positive values of C{sub 5} and defocus C{sub 1} results in the most optimal instrument resolution, and optimization of the CTF has been the subject of several studies. Here we describe a simple design procedure for the CTF that results in a most even transfer of information below the resolution limit. We address not only the resolution of the instrument, but also the stability of the CTF in the presence of small disturbances in C{sub 1} and C{sub 3}. We show that resolution can be traded for stability in a rational and transparent fashion. These topics are discussed quantitatively for both weak-phase and strong-phase (or amplitude) objects. The results apply equally to instruments at high electron energy (TEM) and at very low electron energy (LEEM), as the basic optical properties of the imaging lenses are essentially identical. - Highlights: ► An optimized Contrast Transfer Function for aberration corrected electron microscopes is proposed. ► Based on the properties of the CTF near optimum settings, we address its stability. ► Over some range of parameters resolution can be traded for stability. ► These issues are addressed for weak-phase objects, as well as strong-phase and amplitude object. ► We compare our results with CTF settings previously proposed.

  13. Optimization and stability of the contrast transfer function in aberration-corrected electron microscopy

    The Contrast Transfer Function (CTF) describes the manner in which the electron microscope modifies the object exit wave function as a result of objective lens aberrations. For optimum resolution in C3-corrected microscopes it is well established that a small negative value of C3, offset by positive values of C5 and defocus C1 results in the most optimal instrument resolution, and optimization of the CTF has been the subject of several studies. Here we describe a simple design procedure for the CTF that results in a most even transfer of information below the resolution limit. We address not only the resolution of the instrument, but also the stability of the CTF in the presence of small disturbances in C1 and C3. We show that resolution can be traded for stability in a rational and transparent fashion. These topics are discussed quantitatively for both weak-phase and strong-phase (or amplitude) objects. The results apply equally to instruments at high electron energy (TEM) and at very low electron energy (LEEM), as the basic optical properties of the imaging lenses are essentially identical. - Highlights: ► An optimized Contrast Transfer Function for aberration corrected electron microscopes is proposed. ► Based on the properties of the CTF near optimum settings, we address its stability. ► Over some range of parameters resolution can be traded for stability. ► These issues are addressed for weak-phase objects, as well as strong-phase and amplitude object. ► We compare our results with CTF settings previously proposed

  14. Nanomaterial datasets to advance tomography in scanning transmission electron microscopy

    Levin, Barnaby D A; Chen, Chien-Chun; Scott, M C; Xu, Rui; Theis, Wolfgang; Jiang, Yi; Yang, Yongsoo; Ophus, Colin; Zhang, Haitao; Ha, Don-Hyung; Wang, Deli; Yu, Yingchao; Abruna, Hector D; Robinson, Richard D; Ercius, Peter; Kourkoutis, Lena F; Miao, Jianwei; Muller, David A; Hovden, Robert

    2016-01-01

    Electron tomography in materials science has flourished with the demand to characterize nanoscale materials in three dimensions (3D). Access to experimental data is vital for developing and validating reconstruction methods that improve resolution and reduce radiation dose requirements. This work presents five high-quality scanning transmission electron microscope (STEM) tomography datasets in order to address the critical need for open access data in this field. The datasets represent the current limits of experimental technique, are of high quality, and contain materials with structural complexity. Included are tomographic series of a hyperbranched Co2P nanocrystal, platinum nanoparticles on a carbon nanofibre imaged over the complete 180{\\deg} tilt range, a platinum nanoparticle and a tungsten needle both imaged at atomic resolution by equal slope tomography, and a through-focal tilt series of PtCu nanoparticles. A volumetric reconstruction from every dataset is provided for comparison and development of p...

  15. High order aberration and straylight evaluation after cataract surgery with implantation of an aspheric,aberration correcting monofocal intraocular lens

    Florian; T; A; Kretz; Tamer; Tandogan; Ramin; Khoramnia; Gerd; U; Auffarth

    2015-01-01

    ·AIM: To evaluate the quality of vision in respect to high order aberrations and straylight perception after implantation of an aspheric, aberration correcting,monofocal intraocular lens(IOL).·METHODS: Twenty-one patients(34 eyes) aged 50 to83 y underwent cataract surgery with implantation of an aspheric, aberration correcting IOL(Tecnis ZCB00,Abbott Medical Optics). Three months after surgery they were examined for uncorrected(UDVA) and corrected distance visual acuity(CDVA), contrast sensitivity(CS)under photopic and mesopic conditions with and without glare source, ocular high order aberrations(HOA, Zywave II) and retinal straylight(C-Quant).· RESULTS: Postoperatively, patients achieved a postoperative CDVA of 0.0 log MAR or better in 97.1% of eyes. Mean values of high order abberations were +0.02±0.27(primary coma components) and-0.04 ±0.16(spherical aberration term). Straylight values of the C-Quant were 1.35±0.44 log which is within normal range of age matched phakic patients. The CS measurements under mesopic and photopic conditions in combination with and without glare did not show any statistical significance in the patient group observed(P ≥0.28).· CONCLUSION: The implantation of an aspherical aberration correcting monofocal IOL after cataractsurgery resulted in very low residual higher order aberration(HOA) and normal straylight.

  16. Influence of single-photon-transmission scan duration measured with the ECAT ART PET-scanner

    Aim: The aim was to study the influence of single-photon-transmission scan duration in 3D-PET on the quantitative values of attenuation coefficients and noise in transmission images and of activity concentrations and noise in attenuation corrected emission images of thorax phantom- and patient data. Method and material: Using dual collimated Cs-137 singles transmission sources (Eγ = 662 keV, A = 2* 614 MBq) on an ECAT ART tomography series of transmission scans of a thorax phantom were acquired pre- and post-injection of 18F. 17 patients underwent two transmission scans. The scan time of the short transmission was chosen according to the results of the phantom studies (noise of Poisson statistics less than 4%). Transmission and attenuation corrected emission images were evaluated with respect to estimated linear attenuation coefficients, noise and specific activities in organs. Results: The phantom studies reveal little variation of the estimated linear attenuation coefficients as a function of scan duration. The estimates of the attenuation coefficients are found to be 1% lower than the expected values for pre- and up to 6.5% lower for post-injection transmissions. The noise level in the transmission images increases as expected for Poisson data. The noise level in the attenuation corrected emission images shows only little increase with decreasing transmission scan time whereas it is strongly influenced by a variation of emission scan time. In patient studies, less than 3% difference was found in the estimated linear attenuation coefficients as well as in the activity concentrations between short (pre or post-injection) and long transmission scans. The noise levels in transmission and emission images are 1% (pre-injection) and 4% (post-injection) higher for short transmission scans. Conclusion: Due to the high photon flux, single photon transmission offers good clinical performance with significantly reduced transmission scan durations (<2 min/bed in pre-, <4

  17. Image formation mechanisms of spherical aberration corrected BF STEM imaging methods

    In this study, we explore the formation mechanisms of different spherical-aberration (Cs)-corrected bright-field (BF) scanning transmission electron microscope (STEM) imaging methods. The Cs-corrected BF STEM imaging modes are characterised in detail using simulated images and experimental BF STEM images obtained with several types of detectors. The Co3O4 specimen results show that the occupancy, the atomic spacing, and the atomic number of the atoms constituting the atomic columns control image formation in BF STEM imaging, which is used to detect light atomic columns. The middle-angle BF STEM image is crucial in image formation by BF STEM imaging. - Highlights: • We explore the formation mechanisms of diversified Cs-corrected STEM imaging methods. • SrTiO3 and Co3O4 were observed by several BF STEM imaging methods. • MABF STEM plays a key role in image formation for visualising a light atomic column. • Occupancy, spacing and the atomic number in atomic columns control the image formation

  18. Statistical image reconstruction methods for simultaneous emission/transmission PET scans

    Transmission scans are necessary for estimating the attenuation correction factors (ACFs) to yield quantitatively accurate PET emission images. To reduce the total scan time, post-injection transmission scans have been proposed in which one can simultaneously acquire emission and transmission data using rod sources and sinogram windowing. However, since the post-injection transmission scans are corrupted by emission coincidences, accurate correction for attenuation becomes more challenging. Conventional methods (emission subtraction) for ACF computation from post-injection scans are suboptimal and require relatively long scan times. We introduce statistical methods based on penalized-likelihood objectives to compute ACFs and then use them to reconstruct lower noise PET emission images from simultaneous transmission/emission scans. Simulations show the efficacy of the proposed methods. These methods improve image quality and SNR of the estimates as compared to conventional methods

  19. Scanning transmission electron microscopy: Albert Crewe's vision and beyond

    Some four decades were needed to catch up with the vision that Albert Crewe and his group had for the scanning transmission electron microscope (STEM) in the nineteen sixties and seventies: attaining 0.5 Å resolution, and identifying single atoms spectroscopically. With these goals now attained, STEM developments are turning toward new directions, such as rapid atomic resolution imaging and exploring atomic bonding and electronic properties of samples at atomic resolution. The accomplishments and the future challenges are reviewed and illustrated with practical examples. -- Highlights: ► TV-rate STEM imaging of heavy atoms is demonstrated. ► DNA sequencing by STEM dark field imaging should be possible at a rate of 106 bases/s. ► Individual silicon atom impurities in graphene are imaged atom-by-atom. ► Single atoms of nitrogen and boron incorporated in graphene are imaged spectroscopically. ► Bonding of individual atoms can be probed by analyzing the fine structures of their EEL spectra.

  20. Amyloid Structure and Assembly: Insights from Scanning Transmission Electron Microscopy

    Goldsbury, C.; Wall, J.; Baxa, U.; Simon, M. N.; Steven, A. C.; Engel, A.; Aebi, U.; Muller, S. A.

    2011-01-01

    Amyloid fibrils are filamentous protein aggregates implicated in several common diseases such as Alzheimer's disease and type II diabetes. Similar structures are also the molecular principle of the infectious spongiform encephalopathies such as Creutzfeldt-Jakob disease in humans, scrapie in sheep, and of the so-called yeast prions, inherited non-chromosomal elements found in yeast and fungi. Scanning transmission electron microscopy (STEM) is often used to delineate the assembly mechanism and structural properties of amyloid aggregates. In this review we consider specifically contributions and limitations of STEM for the investigation of amyloid assembly pathways, fibril polymorphisms and structural models of amyloid fibrils. This type of microscopy provides the only method to directly measure the mass-per-length (MPL) of individual filaments. Made on both in vitro assembled and ex vivo samples, STEM mass measurements have illuminated the hierarchical relationships between amyloid fibrils and revealed that polymorphic fibrils and various globular oligomers can assemble simultaneously from a single polypeptide. The MPLs also impose strong constraints on possible packing schemes, assisting in molecular model building when combined with high-resolution methods like solid-state nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR).

  1. Nanomaterial datasets to advance tomography in scanning transmission electron microscopy.

    Levin, Barnaby D A; Padgett, Elliot; Chen, Chien-Chun; Scott, M C; Xu, Rui; Theis, Wolfgang; Jiang, Yi; Yang, Yongsoo; Ophus, Colin; Zhang, Haitao; Ha, Don-Hyung; Wang, Deli; Yu, Yingchao; Abruña, Hector D; Robinson, Richard D; Ercius, Peter; Kourkoutis, Lena F; Miao, Jianwei; Muller, David A; Hovden, Robert

    2016-01-01

    Electron tomography in materials science has flourished with the demand to characterize nanoscale materials in three dimensions (3D). Access to experimental data is vital for developing and validating reconstruction methods that improve resolution and reduce radiation dose requirements. This work presents five high-quality scanning transmission electron microscope (STEM) tomography datasets in order to address the critical need for open access data in this field. The datasets represent the current limits of experimental technique, are of high quality, and contain materials with structural complexity. Included are tomographic series of a hyperbranched Co2P nanocrystal, platinum nanoparticles on a carbon nanofibre imaged over the complete 180° tilt range, a platinum nanoparticle and a tungsten needle both imaged at atomic resolution by equal slope tomography, and a through-focal tilt series of PtCu nanoparticles. A volumetric reconstruction from every dataset is provided for comparison and development of post-processing and visualization techniques. Researchers interested in creating novel data processing and reconstruction algorithms will now have access to state of the art experimental test data. PMID:27272459

  2. High-resolution imaging in the scanning transmission electron microscope

    The high-resolution imaging of crystalline materials in the scanning transmission electron microscopy (STEM) is reviewed with particular emphasis on the conditions under which an incoherent image can be obtained. It is shown that a high-angle annular detector can be used to break the coherence of the imaging process, in the transverse plane through the geometry of the detector, or in three dimensions if multiphonon diffuse scattering is detected. In the latter case, each atom can be treated as a highly independent source of high-angle scattering. The most effective fast electron states are therefore tightly bound s-type Bloch states. Furthermore, they add constructively for each incident angle in the coherent STEM probe, so that s states are responsible for practically the entire image contrast. Dynamical effects are largely removed, and almost perfect incoherent imaging is achieved. s states are relatively insensitive to neighboring strings, so that incoherent imaging is maintained for superlattice and interfaces, and supercell calculations are unnecessary. With an optimum probe profile, the incoherent image represents a direct image of the crystal projection, with compositional sensitivity built in through the strong dependence of the scattering cross sections on atomic number Z

  3. Double-aberration corrected TEM/STEM of solid acid nanocatalysts in the development of pharmaceutical NSAIDS

    Yoshida, K.; Shiju, N.; Brown, R.; Wright, I.; Boyes, E. D.; Gai, P. L.

    2012-07-01

    We report nanostructural and physico-chemical studies in the development of an efficient low temperature heterogeneous catalytic process for nonsteroidal anti-inflammatory drugs (NSAIDS) such as N-acetyl-p-aminophenol (paracetamol or acetaminophen) on tungstated zirconia nanocatalysts. Using a double-aberration corrected TEM/STEM, modified in-house for in-situ studies at the sub-Angstrom level, we directly observed in real-time, the dynamic precursor transformation to the active catalyst. We quantified the observations with catalytic activity studies for the NSAIDS. The studies have provided the direct evidence for single tungsten promoter atoms and surface WOx species of pharmaceuticals.

  4. [Aberration corrected intraocular lens for microincision cataract surgery (MICS). Intraindividual comparison with a conventional lens - 1-year follow-up].

    Möglich, M; Häberle, H; Pham, D T; Wirbelauer, C

    2009-10-01

    Microincision cataract surgery (MICS) is an important advancement in the field of cataract surgery. This article compares an aberration corrected hydrophilic acrylic intraocular lens (IOL) having a hydrophobic surface for MICS with a one-piece hydrophobic acrylic IOL with respect to capsule sac stability, image quality, and after-cataract formation over the course of 1 year. The operations were performed as bimanual MICS or coaxial phacoemulsification. Overall the results after implantation of the IOL by MICS can be regarded as positive in comparison to the standard operation. PMID:18836727

  5. Study on the use of transmission scans for whole body PET attenuation correction

    Transmission scans for attenuation correction of whole body PET studies are not acquired routinely, since noise considerations impose acquisition time constraints that make conventional scanning techniques infeasible. The aim of this work is to optimize data acquisition and processing parameters and improve the SNR of whole body transmission scans, in order to achieve within a reasonable time frame, an attenuation correction of the same quality as in cardiac PET. Methods to improve the scanner sensitivity by using additional coincidence planes, as well as smoothing methods for the randoms and the transmission data were investigated. Phantom and patient studies show that transmission scans are feasible for whole body PET studies, with equivalent noise introduced in the chest area as in a typical cardiac PET attenuation correction, at fractions of the time required by conventional transmission scan protocols

  6. Comparison of analytical and numerical approaches for CT-based aberration correction in transcranial passive acoustic imaging

    Jones, Ryan M.; Hynynen, Kullervo

    2016-01-01

    Computed tomography (CT)-based aberration corrections are employed in transcranial ultrasound both for therapy and imaging. In this study, analytical and numerical approaches for calculating aberration corrections based on CT data were compared, with a particular focus on their application to transcranial passive imaging. Two models were investigated: a three-dimensional full-wave numerical model (Connor and Hynynen 2004 IEEE Trans. Biomed. Eng. 51 1693-706) based on the Westervelt equation, and an analytical method (Clement and Hynynen 2002 Ultrasound Med. Biol. 28 617-24) similar to that currently employed by commercial brain therapy systems. Trans-skull time delay corrections calculated from each model were applied to data acquired by a sparse hemispherical (30 cm diameter) receiver array (128 piezoceramic discs: 2.5 mm diameter, 612 kHz center frequency) passively listening through ex vivo human skullcaps (n  =  4) to emissions from a narrow-band, fixed source emitter (1 mm diameter, 516 kHz center frequency). Measurements were taken at various locations within the cranial cavity by moving the source around the field using a three-axis positioning system. Images generated through passive beamforming using CT-based skull corrections were compared with those obtained through an invasive source-based approach, as well as images formed without skull corrections, using the main lobe volume, positional shift, peak sidelobe ratio, and image signal-to-noise ratio as metrics for image quality. For each CT-based model, corrections achieved by allowing for heterogeneous skull acoustical parameters in simulation outperformed the corresponding case where homogeneous parameters were assumed. Of the CT-based methods investigated, the full-wave model provided the best imaging results at the cost of computational complexity. These results highlight the importance of accurately modeling trans-skull propagation when calculating CT-based aberration corrections

  7. Prospects for versatile phase manipulation in the TEM : beyond aberration correction

    Guzzinati, Giulio; Clark, Laura; Béché, Armand; Juchtmans, Roeland; Boxem, van, Tj.; Mazilu, Michael; Verbeeck, Jo

    2015-01-01

    Abstract: In this paper we explore the desirability of a transmission electron microscope in which the phase of the electron wave can be freely controlled. We discuss different existing methods to manipulate the phase of the electron wave and their limitations. We show how with the help of current techniques the electron wave can already be crafted into specific classes of waves each having their own peculiar properties. Assuming a versatile phase modulation device is feasible, we explore pos...

  8. Smart microscope: an adaptive optics learning system for aberration correction in multiphoton confocal microscopy.

    Albert, O; Sherman, L; Mourou, G; Norris, T B; Vdovin, G

    2000-01-01

    Off-axis aberrations in a beam-scanning multiphoton confocal microscope are corrected with a deformable mirror. The optimal mirror shape for each pixel is determined by a genetic learning algorithm, in which the second-harmonic or two-photon fluorescence signal from a reference sample is maximized. The speed of the convergence is improved by use of a Zernike polynomial basis for the deformable mirror shape. This adaptive optical correction scheme is implemented in an all-reflective system by use of extremely short (10-fs) optical pulses, and it is shown that the scanning area of an f:1 off-axis parabola can be increased by nine times with this technique. PMID:18059779

  9. Double-aberration corrected TEM/STEM of solid acid nanocatalysts in the development of pharmaceutical NSAIDS

    We report nanostructural and physico-chemical studies in the development of an efficient low temperature heterogeneous catalytic process for nonsteroidal anti-inflammatory drugs (NSAIDS) such as N-acetyl-p-aminophenol (paracetamol or acetaminophen) on tungstated zirconia nanocatalysts. Using a double-aberration corrected TEM/STEM, modified in-house for in-situ studies at the sub-Angstrom level, we directly observed in real-time, the dynamic precursor transformation to the active catalyst. We quantified the observations with catalytic activity studies for the NSAIDS. The studies have provided the direct evidence for single tungsten promoter atoms and surface WOx species of ≤ 0.35 nm, with nanoclusters of WOx (0.6 to 1nm), located at grain boundaries on the surface of the zirconia nanoparticles. The correlation between the nanostructure and catalytic activity indicates that the species create Broensted acid sites highly active for the low temperature process. The results open up opportunities for developing green heterogeneous methods for pharmaceuticals.

  10. Scanning image detection (SID) system for conventional transmission electron microscope (CTEM) images.

    Tanji, T; Tomita, M; Kobayashi, H

    1990-08-01

    A new image detection system has been developed to display transmission electron microscope (TEM) images on a CRT without a video camera system. Deflection coils placed in both the upper space of an objective lens and in the lower space of the first intermediate lens scan a small electron probe simultaneously. The electrical signal acquired through an improved scintillator and a photomultiplier is synchronized with the scanning signal and displayed in a similar fashion to a conventional scanning TEM (STEM) instrument. A preliminary system using a 100 kV conventional TEM (CTEM) equipped with a hairpin-type electron gun, produced an image with a spatial resolution of 1 nm. PMID:2391565

  11. Quantitative Phase Imaging with a Scanning Transmission X-Ray Microscope

    de Jonge, M. D.; Hornberger, B.; C. Holzner; Legnini, D.; Paterson, D.; McNulty, I.; Jacobsen, C.; Vogt, S.

    2008-01-01

    We obtain quantitative phase reconstructions from differential phase contrast images obtained with a scanning transmission x-ray microscope and 2.5 keV x rays. The theoretical basis of the technique is presented along with measurements and their interpretation.

  12. In-situ scanning transmission X-ray microscopy of catalytic materials under reaction conditions

    de Smit, E.; Creemer, J.F.; Zandbergen, H.W.; Weckhuysen, B.M.; de Groot, F.M.F.

    2009-01-01

    In-situ Scanning X-ray Transmission Microscopy (STXM) allows the measurement of the soft X-ray absorption spectra with 10 to 30 nm spatial resolution under realistic reaction conditions. We show that STXM-XAS in combination with a micromachined nanoreactor can image a catalytic system under relevant

  13. Reply to L.M. Brown et al. "Brief history of the Cambridge STEM aberration correction project and its progeny" in Ultramicroscopy 157, 88 (2015).

    Urban, K W; Rose, H

    2016-02-01

    We comment on a Short Communication recently published in Ultramicroscopy in which Brown et al. criticize our description of the time sequence of events in the development of aberration correction systems in electron optics during the 1990s put forward in the introduction to the Ultramicroscopy April 2015 Special Issue. We present an analysis of the published literature furnishing evidence that our description is correct. PMID:26624509

  14. Design and Performance Characteristics of the ORNL Advanced Microscopy Laboratory and JEOL 2200FS-AC Aberration-Corrected STEM/TEM

    Lawrence F. Allard; Douglas A. Blom; O'Keefe, Michael A.; Mishina, S.

    2005-01-01

    At ORNL, the new Advanced Microscopy Laboratory (AML) has recently been completed, with two aberration-corrected instruments installed, and two more planned in the near future to fill the 4-laboratory building. The installed JEOL 2200FS-AC has demonstrated a TEM information limit of 0.9A. This limit is expected given the measured instrument parameters (HT and OL power supply stabilities, beam energy spread, etc.), and illustrates that the environmental influences are not adversely affect...

  15. Study of Interactions Between Microbes and Minerals by Scanning Transmission X-Ray Microscopy (STXM)

    Benzerara, K.; /Paris U., VI-VII, LMCP; Tyliszczak, T.; /LBNL, ALS; Brown, G.E., Jr.; /Stanford U., Geo. Environ. Sci. /SLAC, SSRL

    2007-01-03

    Scanning Transmission X-ray Microscopy (STXM) and Transmission Electron Microscopy (TEM) were combined to characterize various samples of geomicrobiological interest down to the nanometer scale. An approach based on energy-filtered imaging was used to examine microbe-mineral interactions and the resulting biominerals, as well as biosignatures in simplified laboratory samples. This approach was then applied to natural samples, including natural biofilms entombed in calcium carbonate precipitates and bioweathered silicates and facilitated location of bacterial cells and provided unique insights about their biogeochemical interactions with minerals at the 30-40 nm scale.

  16. A dual-energy transmission detector for vehicle scanning using wavelength-shifting fibers

    Van Liew, Seth; Zhang, Ming

    2014-09-01

    A new dual energy detector for vehicle scanning is presented. The system is composed of a three-sided Compton backscatter imaging system utilizing flying-spot x-rays concurrent with a transmission detector using the same x-ray beam. This detector is under the vehicle and is thin enough to be driven over with a modest bump which does not impede vehicle trac. It uses sheet scintillator with wavelength-shifting fibers as light pipes. Results are presented on steel penetration, calibration procedures and issues, and dual energy performance. The system's dose is low enough for scanning people, including passenger vehicles.

  17. Valence electron energy-loss spectroscopy in monochromated scanning transmission electron microscopy

    With the development of monochromators for (scanning) transmission electron microscopes, valence electron energy-loss spectroscopy (VEELS) is developing into a unique technique to study the band structure and optical properties of nanoscale materials. This article discusses practical aspects of spatially resolved VEELS performed in scanning transmission mode and the alignments necessary to achieve the current optimum performance of ∼0.15 eV energy resolution with an electron probe size of ∼1 nm. In particular, a collection of basic concepts concerning the acquisition process, the optimization of the energy resolution, the spatial resolution and the data processing are provided. A brief study of planar defects in a Y1Ba2Cu3O7-δ high-temperature superconductor illustrates these concepts and shows what kind of information can be accessed by VEELS

  18. A scanning and transmission electron microscopic study of the membranes of chicken egg

    Tan, C K; Chen, T. W.; Chan, H L; Ng, L. S.

    1992-01-01

    Questions regarding the structure of the inner and outer shell membranes of the chicken egg were addressed in this study by correlating observations from light microscopy and scanning and transmission electron microscopy. The egg membrane had a limiting membrane, which measured .9 to .15 pn in thickness and appeared to be a continuous and an impervious layer, but the shell membrane did not. Under the SEM, each membrane was seen to be made up of severa1 fibre ...

  19. Transmission-scanning electron microscopic observations of selected Eikenella corrodens strains.

    Progulske, A; Holt, S C

    1980-01-01

    The morphology of Eikenella corrodens 333/54-55 (ATCC 23834) and two human periodontal lesion isolates, strains 470 and 373, was examined by transmission and scanning electron microscopy. All strains exhibited a cell envelope characteristic of gram-negative bacteria. Staining with ruthenium red and alcian blue revealed a loosely organized fibrous slime layer associated with the outer surface of the outer membrane. Slime "stabilization" was achieved by incubation of cells with antisera prepare...

  20. Confocal soft X-ray scanning transmission microscopy: setup, alignment procedure and limitations

    Späth, Andreas; Raabe, Jörg; Rainer H. Fink

    2015-01-01

    Zone-plate-based scanning transmission soft X-ray microspectroscopy (STXM) is a well established technique for high-contrast imaging of sufficiently transparent specimens (e.g. ultrathin biological tissues, polymer materials, archaeometric specimens or magnetic thin films) with spatial resolutions in the regime of 20 nm and high spectroscopic or chemical sensitivity. However, due to the relatively large depth of focus of zone plates, the resolution of STXM along the optical axis so far stays ...

  1. Electro-deposition of Cu studied with in situ electrochemical scanning transmission x-ray microscopy

    Hitchcock, A. P.; Qin, Z.; Rosendahl, S. M.; Lee, V.; Reynolds, M.; Hosseinkhannazer, H.

    2016-01-01

    Soft X-ray scanning transmission X-ray microscopy (STXM) was used to investigate Cu deposition onto, and stripping from a Au surface. Cu 2p spectromicroscopy was used to analyze initial and final states (ex situ processing) and follow the processes in situ. The in situ experiments were carried out using a static electrochemical cell with an electrolyte layer thickness of ˜1 μm. A new apparatus for in situ electrochemical STXM is described.

  2. In-situ scanning transmission X-ray microscopy of catalytic materials under reaction conditions

    Smit, E.; Creemer, J.F.; H.W. Zandbergen; Weckhuysen, B. M.; Groot, F.M.F. de

    2009-01-01

    In-situ Scanning X-ray Transmission Microscopy (STXM) allows the measurement of the soft X-ray absorption spectra with 10 to 30 nm spatial resolution under realistic reaction conditions. We show that STXM-XAS in combination with a micromachined nanoreactor can image a catalytic system under relevant reaction conditions, and provide detailed information on the morphology and composition of the catalyst material. The nanometer resolution combined with powerful chemical speciation by XAS and the...

  3. Advanced scanning transmission stereo electron microscopy of structural and functional engineering materials

    Agudo Jácome, L.; Eggeler, G.; Dlouhý, Antonín

    2012-01-01

    Roč. 122, NOV (2012), s. 48-59. ISSN 0304-3991 R&D Projects: GA ČR GA202/09/2073 Institutional research plan: CEZ:AV0Z20410507 Keywords : stereoscopy * scanning transmission electron microscopy * single crystal Ni-base superalloys * Dislocation substructures * Foil thickness measurement Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.470, year: 2012

  4. Examination Of Defect In Gas Pipeline By Gamma Transmission Scanning And Computed Tomography Techniques

    The transmission gamma scanning and computed tomography (CT) are advanced non-destructive testing techniques which can provide visual information to end-user. In recent years, industrial gamma scanning and CT equipment have been continuously improved in physical configuration and image reconstruction software have been supplemented with advanced algorithms, that can satisfy end-users with high quality computed tomography images. The first generation CT system with configuration of one source - one detector which is designed and fabricated by the Centre for Applications of Nuclear Technique in Industry (CANTI) is a dedicated equipment for examination of corrosion, erosion or blockage in petroleum pipeline. The equipment have two options of measurement: gamma transmission scanning and computed tomography scanning. The associated image reconstruction software have three image reconstruction algorithms: analytical (FBP), algebraic (ART) and statistical (EM) along with some advanced image processing techniques. CANTI had utilized the equipment to examine some fraction of gas transportation pipeline of PetroVietnam Gas Company, detected and evaluated the extent of defects, quickly providing useful information for the inspection and maintenance tasks of the client. (author)

  5. Method and apparatus for a high-resolution three dimensional confocal scanning transmission electron microscope

    de Jonge, Niels [Oak Ridge, TN

    2010-08-17

    A confocal scanning transmission electron microscope which includes an electron illumination device providing an incident electron beam propagating in a direction defining a propagation axis, and a precision specimen scanning stage positioned along the propagation axis and movable in at least one direction transverse to the propagation axis. The precision specimen scanning stage is configured for positioning a specimen relative to the incident electron beam. A projector lens receives a transmitted electron beam transmitted through at least part of the specimen and focuses this transmitted beam onto an image plane, where the transmitted beam results from the specimen being illuminated by the incident electron beam. A detection system is placed approximately in the image plane.

  6. Efficient linear phase contrast in scanning transmission electron microscopy with matched illumination and detector interferometry.

    Ophus, Colin; Ciston, Jim; Pierce, Jordan; Harvey, Tyler R; Chess, Jordan; McMorran, Benjamin J; Czarnik, Cory; Rose, Harald H; Ercius, Peter

    2016-01-01

    The ability to image light elements in soft matter at atomic resolution enables unprecedented insight into the structure and properties of molecular heterostructures and beam-sensitive nanomaterials. In this study, we introduce a scanning transmission electron microscopy technique combining a pre-specimen phase plate designed to produce a probe with structured phase with a high-speed direct electron detector to generate nearly linear contrast images with high efficiency. We demonstrate this method by using both experiment and simulation to simultaneously image the atomic-scale structure of weakly scattering amorphous carbon and strongly scattering gold nanoparticles. Our method demonstrates strong contrast for both materials, making it a promising candidate for structural determination of heterogeneous soft/hard matter samples even at low electron doses comparable to traditional phase-contrast transmission electron microscopy. Simulated images demonstrate the extension of this technique to the challenging problem of structural determination of biological material at the surface of inorganic crystals. PMID:26923483

  7. Laser transmission welding of Clearweld-coated polyethylene glycol terephthalate by incremental scanning technique

    Wang, Y. Y.; Wang, A. H.; Weng, Z. K.; Xia, H. B.

    2016-06-01

    Transmission laser welding using Incremental Scanning Technique(TWIST) mode and conventional contour welding mode were adopted to investigate laser transmission welding of 0.5 mm thick PET plate. A 1064 nm fiber laser was used to weld PET at the (TWIST) mode, and an 808 nm diode laser was applied to conduct the conventional contour welding. The Clearweld coating was used as laser absorbing material. The influences of laser parameters (i.e. defocusing distance, distance between two circles) on the quality of weld seams were analyzed by optical microscopy. Moreover, geometry and shear strength of the weld zone were tested to optimize laser parameters. Additionally, the water vapor permeability (WVP) of weld seams was measured to test hermetical capacity. Results show that the shear strength and hermetic capacity of weld seam by TWIST mode are at the same level in comparison with that of the conventional contour welding.

  8. Efficient linear phase contrast in scanning transmission electron microscopy with matched illumination and detector interferometry

    Ophus, Colin; Ciston, Jim; Pierce, Jordan; Harvey, Tyler R.; Chess, Jordan; McMorran, Benjamin J.; Czarnik, Cory; Rose, Harald H.; Ercius, Peter

    2016-02-01

    The ability to image light elements in soft matter at atomic resolution enables unprecedented insight into the structure and properties of molecular heterostructures and beam-sensitive nanomaterials. In this study, we introduce a scanning transmission electron microscopy technique combining a pre-specimen phase plate designed to produce a probe with structured phase with a high-speed direct electron detector to generate nearly linear contrast images with high efficiency. We demonstrate this method by using both experiment and simulation to simultaneously image the atomic-scale structure of weakly scattering amorphous carbon and strongly scattering gold nanoparticles. Our method demonstrates strong contrast for both materials, making it a promising candidate for structural determination of heterogeneous soft/hard matter samples even at low electron doses comparable to traditional phase-contrast transmission electron microscopy. Simulated images demonstrate the extension of this technique to the challenging problem of structural determination of biological material at the surface of inorganic crystals.

  9. Probing carbon coatings on nanoparticle decorated carbon nanotubes by scanning transmission X-ray microscopy

    Li, Ming; Gao, Jing; Bai, Lili; Pu, Aiwu; Liu, Jinyin; Zhao, Guanqi; Sun, Xuhui; Zhong, Jun, E-mail: jzhong@suda.edu.cn

    2013-11-15

    Two kinds of carbon coating on carbon nanotubes (CNTs) after decoration with nanoparticles were observed by scanning transmission X-ray microscopy with a concurrent characterization of the electronic structure, revealing the complex compositions in CNTs after chemical modification. Moreover, a sandwich structure shown as CNT-nanoparticle-coating can be created with the exposure to X-ray for CNTs decorated with nanoparticle outside the wall. The coating shows an effective way for site-selective modification of CNTs with various carbon structures.

  10. Reliable strain measurement in transistor arrays by robust scanning transmission electron microscopy

    Suhyun Kim

    2013-09-01

    Full Text Available Accurate measurement of the strain field in the channels of transistor arrays is critical for strain engineering in modern electronic devices. We applied atomic-resolution high-angle annular dark-field scanning transmission electron microscopy to quantitative measurement of the strain field in transistor arrays. The quantitative strain profile over 20 transistors was obtained with high reliability and a precision of 0.1%. The strain field was found to form homogeneously in the channels of the transistor arrays. Furthermore, strain relaxation due to the thin foil effect was quantitatively investigated for thicknesses of 35 to 275 nm.

  11. Investigation of Exchange Coupled Composites with Scanning Transmission X-ray Microscopy

    Full text: Novel exchange coupled composites incorporating a hard and a soft magnetic layer have the potential for a number of applications including magnetic recording, sensors, MRAM and oscillators. We investigate the magnetic behaviour of ferromagnetic L10 FePt thin films exchange coupled to soft ferrimagnets, including FeGd and FeTb, using Scanning Transmission X-ray Microscopy (STXM), which allows us to probe each layer individually, and magnetic force microscopy (MFM). Using a luminescence detection scheme, we are able to determine the magnetic domain configuration using STXM. From MFM measurements we find a compositional dependence of the domain structure in the ferrimagnetic films. (author)

  12. Compact scanning transmission x-ray microscope at the photon factory

    Takeichi, Yasuo, E-mail: yasuo.takeichi@kek.jp; Inami, Nobuhito; Ono, Kanta [High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba 305-0801 (Japan); Suga, Hiroki [Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526 (Japan); Takahashi, Yoshio [Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526 (Japan); The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)

    2016-01-28

    We report the design and performance of a compact scanning transmission X-ray microscope developed at the Photon Factory. Piezo-driven linear stages are used as coarse stages of the microscope to realize excellent compactness, mobility, and vibrational and thermal stability. An X-ray beam with an intensity of ∼10{sup 7} photons/s was focused to a diameter of ∼40 nm at the sample. At the soft X-ray undulator beamline used with the microscope, a wide range of photon energies (250–1600 eV) is available. The microscope has been used to research energy materials and in environmental sciences.

  13. Surface sensitivity in scanning transmission x-ray microspectroscopy using secondary electron detection.

    Hub, C; Wenzel, S; Raabe, J; Ade, H; Fink, R H

    2010-03-01

    The successful integration of electron detection into an existing scanning transmission x-ray microspectroscope (STXM) at the Swiss Light Source is demonstrated. In conventional x-ray detection using a photomultiplier, STXM offers mainly bulk sensitivity combined with high lateral resolution. However, by implementation of a channeltron electron multiplier, the surface sensitivity can be established by the detection of secondary electrons emitted from the sample upon resonant excitation. We describe the experimental setup and discuss several relevant aspects, in particular the schemes to correct for self-absorption in the specimen due to back illumination in case of thicker films. PMID:20370182

  14. Development of scanning transmission ion microscopy computed tomography at Fudan Microbeam line

    The computed tomography was applied to setting STIM (Scanning Transmission Ion Microscopy) projections recorded at the Fudan Ion Beam Laboratory. In this work, in order to visualize the three-dimensional mass density distribution in several specimens, example for a test structure of hollow gold cylinder was presented together with a detailed description of the developed system, including data reconstruction code (Tomorebuild 2) and image display software (AMIRA®). Future development will allow the particle induced X-ray emission tomography for elemental analysis of micrometer-sized samples. (authors)

  15. Compact scanning transmission x-ray microscope at the photon factory

    Takeichi, Yasuo; Inami, Nobuhito; Suga, Hiroki; Takahashi, Yoshio; Ono, Kanta

    2016-01-01

    We report the design and performance of a compact scanning transmission X-ray microscope developed at the Photon Factory. Piezo-driven linear stages are used as coarse stages of the microscope to realize excellent compactness, mobility, and vibrational and thermal stability. An X-ray beam with an intensity of ˜107 photons/s was focused to a diameter of ˜40 nm at the sample. At the soft X-ray undulator beamline used with the microscope, a wide range of photon energies (250-1600 eV) is available. The microscope has been used to research energy materials and in environmental sciences.

  16. Scanning transmission x-ray microscope for materials science spectromicroscopy at the ALS

    Warwick, T.; Seal, S.; Shin, H. [Ernest Orlando Lawrence Berkeley National Lab., CA (United States)] [and others

    1997-04-01

    The brightness of the Advanced Light Source will be exploited by several new instruments for materials science spectromicroscopy over the next year or so. The first of these to become operational is a scanning transmission x-ray microscope with which near edge x-ray absorption spectra (NEXAFS) can be measured on spatial features of sub-micron size. Here the authors describe the instrument as it is presently implemented, its capabilities, some studies made to date and the developments to come. The Scanning Transmission X-ray Microscope makes use of a zone plate lens to produce a small x-ray spot with which to perform absorption spectroscopy through thin samples. The x-ray beam from ALS undulator beamline 7.0 emerges into the microscope vessel through a silicon nitride vacuum window 160nm thick and 300{mu}m square. The vessel is filled with helium at atmospheric pressure. The zone plate lens is illuminated 1mm downstream from the vacuum window and forms an image in first order of a pinhole which is 3m upstream in the beamline. An order sorting aperture passes the first order converging light and blocks the unfocused zero order. The sample is at the focus a few mm downstream of the zone plate and mounted from a scanning piezo stage which rasters in x and y so that an image is formed, pixel by pixel, by an intensity detector behind the sample. Absorption spectra are measured point-by-point as the photon energy is scanned by rotating the diffraction grating in the monochromator and changing the undulator gap.

  17. Transmission scans using Gd-153 line sources in cardiac SPECT studies: What is the additional patient radiation dose burden?

    Aim: To determine the contribution of transmission scan acquisition obtained for attenuation/scatter correction to total patient effective dose from cardiac SPECT studies. Materials and Methods: A dual-headed L-shaped gamma camera equipped with a transmission scan acquisition system based on two 153Gd line sources was used. Transmission scan acquisition was performed on a humanoid phantom. Thermoluminescence dosimeters were used to directly monitor the dose to 550 measuring points in the phantom. Patient effective dose and associated risk from transmission scans acquisition were estimated and compared to those associated to the radiopharmaceutical injected. Results: The maximum effective dose from a typical transmission measurements acquisition was 1.3 μSv and 1.9 μSv for male and female patients, respectively. The contribution of the typical transmission scans acquisition to total patient radiation risk from a cardiac SPECT study was less than 10-3. Conclusion: Radiation exposure may not be considered as a limiting factor for the clinical application of attenuation correction methods based on transmission measurements in cardiac SPECT

  18. Transmissive liquid-crystal device correcting primary coma aberration and astigmatism in laser scanning microscopy

    Tanabe, Ayano; Hibi, Terumasa; Ipponjima, Sari; Matsumoto, Kenji; Yokoyama, Masafumi; Kurihara, Makoto; Hashimoto, Nobuyuki; Nemoto, Tomomi

    2016-03-01

    Laser scanning microscopy allows 3D cross-sectional imaging inside biospecimens. However, certain aberrations produced can degrade the quality of the resulting images. We previously reported a transmissive liquid-crystal device that could compensate for the predominant spherical aberrations during the observations, particularly in deep regions of the samples. The device, inserted between the objective lens and the microscope revolver, improved the image quality of fixed-mouse-brain slices that were observed using two-photon excitation laser scanning microscopy, which was originally degraded by spherical aberration. In this study, we developed a transmissive device that corrects primary coma aberration and astigmatism, motivated by the fact that these asymmetric aberrations can also often considerably deteriorate image quality, even near the sample surface. The device's performance was evaluated by observing fluorescent beads using single-photon excitation laser scanning microscopy. The fluorescence intensity in the image of the bead under a cover slip tilted in the y-direction was increased by 1.5 times after correction by the device. Furthermore, the y- and z-widths of the imaged bead were reduced to 66% and 65%, respectively. On the other hand, for the imaged bead sucked into a glass capillary in the longitudinal x-direction, correction with the device increased the fluorescence intensity by 2.2 times compared to that of the aberrated image. In addition, the x-, y-, and z-widths of the bead image were reduced to 75%, 53%, and 40%, respectively. Our device successfully corrected several asymmetric aberrations to improve the fluorescent signal and spatial resolution, and might be useful for observing various biospecimens.

  19. High Dynamic Range Pixel Array Detector for Scanning Transmission Electron Microscopy

    Tate, Mark W; Chamberlain, Darol; Nguyen, Kayla X; Hovden, Robert M; Chang, Celesta S; Deb, Pratiti; Turgut, Emrah; Heron, John T; Schlom, Darrell G; Ralph, Daniel C; Fuchs, Gregory D; Shanks, Katherine S; Philipp, Hugh T; Muller, David A; Gruner, Sol M

    2015-01-01

    We describe a hybrid pixel array detector (EMPAD - electron microscope pixel array detector) adapted for use in electron microscope applications, especially as a universal detector for scanning transmission electron microscopy. The 128 x 128 pixel detector consists of a 500 um thick silicon diode array bump-bonded pixel-by-pixel to an application-specific integrated circuit (ASIC). The in-pixel circuitry provides a 1,000,000:1 dynamic range within a single frame, allowing the direct electron beam to be imaged while still maintaining single electron sensitivity. A 1.1 kHz framing rate enables rapid data collection and minimizes sample drift distortions while scanning. By capturing the entire unsaturated diffraction pattern in scanning mode, one can simultaneously capture bright field, dark field, and phase contrast information, as well as being able to analyze the full scattering distribution, allowing true center of mass imaging. The scattering is recorded on an absolute scale, so that information such as loc...

  20. High Dynamic Range Pixel Array Detector for Scanning Transmission Electron Microscopy.

    Tate, Mark W; Purohit, Prafull; Chamberlain, Darol; Nguyen, Kayla X; Hovden, Robert; Chang, Celesta S; Deb, Pratiti; Turgut, Emrah; Heron, John T; Schlom, Darrell G; Ralph, Daniel C; Fuchs, Gregory D; Shanks, Katherine S; Philipp, Hugh T; Muller, David A; Gruner, Sol M

    2016-02-01

    We describe a hybrid pixel array detector (electron microscope pixel array detector, or EMPAD) adapted for use in electron microscope applications, especially as a universal detector for scanning transmission electron microscopy. The 128×128 pixel detector consists of a 500 µm thick silicon diode array bump-bonded pixel-by-pixel to an application-specific integrated circuit. The in-pixel circuitry provides a 1,000,000:1 dynamic range within a single frame, allowing the direct electron beam to be imaged while still maintaining single electron sensitivity. A 1.1 kHz framing rate enables rapid data collection and minimizes sample drift distortions while scanning. By capturing the entire unsaturated diffraction pattern in scanning mode, one can simultaneously capture bright field, dark field, and phase contrast information, as well as being able to analyze the full scattering distribution, allowing true center of mass imaging. The scattering is recorded on an absolute scale, so that information such as local sample thickness can be directly determined. This paper describes the detector architecture, data acquisition system, and preliminary results from experiments with 80-200 keV electron beams. PMID:26750260

  1. Localization of human immunodeficiency virus antigens in infected cells by scanning/transmission-immunogold techniques

    An application of high resolution scanning/transmission electron microscopy (STEM) and gold-labelling techniques for the rapid detection of human immunodeficiency virus (HIV) in infected cells has been developed. Experimental in vitro studies for detecting two HIV structural proteins, gp41 and p17, were performed following an indirect labeling procedure that uses monoclonal anti-p17 and anti-gp41 antibodies as primary antibodies and 40 nm gold-linked goat antimouse IgG as secondary antibodies. The cells were then studied by STEM in the scanning mode. Unambiguous localization of the viral antigens was possible by combining the three-dimensional image provided by the secondary electron image and the atomic number-dependent backscattered electron image for the identification of the gold marker. This technique combines both the morphological information and the rapid procedures of scanning electron microscopy with the precise and sensitive antigen detection provided by the use of STEM and immunological methods. The preliminary results of its application to the study of peripheral blood mononuclear cells from four anti-HIV-seropositive patients showing the presence of specific labeling in all of them suggest that it might prove useful for early detection of HIV infection before seroconversion, as well as for quantitative studies

  2. Large-scale Scanning Transmission Electron Microscopy (Nanotomy) of Healthy and Injured Zebrafish Brain.

    Kuipers, Jeroen; Kalicharan, Ruby D; Wolters, Anouk H G; van Ham, Tjakko J; Giepmans, Ben N G

    2016-01-01

    Large-scale 2D electron microscopy (EM), or nanotomy, is the tissue-wide application of nanoscale resolution electron microscopy. Others and we previously applied large scale EM to human skin pancreatic islets, tissue culture and whole zebrafish larvae(1-7). Here we describe a universally applicable method for tissue-scale scanning EM for unbiased detection of sub-cellular and molecular features. Nanotomy was applied to investigate the healthy and a neurodegenerative zebrafish brain. Our method is based on standardized EM sample preparation protocols: Fixation with glutaraldehyde and osmium, followed by epoxy-resin embedding, ultrathin sectioning and mounting of ultrathin-sections on one-hole grids, followed by post staining with uranyl and lead. Large-scale 2D EM mosaic images are acquired using a scanning EM connected to an external large area scan generator using scanning transmission EM (STEM). Large scale EM images are typically ~ 5 - 50 G pixels in size, and best viewed using zoomable HTML files, which can be opened in any web browser, similar to online geographical HTML maps. This method can be applied to (human) tissue, cross sections of whole animals as well as tissue culture(1-5). Here, zebrafish brains were analyzed in a non-invasive neuronal ablation model. We visualize within a single dataset tissue, cellular and subcellular changes which can be quantified in various cell types including neurons and microglia, the brain's macrophages. In addition, nanotomy facilitates the correlation of EM with light microscopy (CLEM)(8) on the same tissue, as large surface areas previously imaged using fluorescent microscopy, can subsequently be subjected to large area EM, resulting in the nano-anatomy (nanotomy) of tissues. In all, nanotomy allows unbiased detection of features at EM level in a tissue-wide quantifiable manner. PMID:27285162

  3. Zone-Doubled Fresnel Zone Plates for Scanning Transmission X-ray Microscopy

    Vila-Comamala, J.; Gorelick, S.; Färm, E.; Kewish, C. M.; Diaz, A.; Guzenko, V. A.; Barrett, R.; Raabe, J.; Menzel, A.; Bunk, O.; Ritala, M.; David, C.

    2011-09-01

    We demonstrate the highest spatial resolution reported in scanning transmission x-ray microscopy to date. For the first time in x-ray microscopy, features below 10 nm in width were resolved in the soft x-ray regime (1.2 keV) and 20-nm lines and spaces were visible at multi-keV photon energies (6.2 keV). These achievements were accomplished using zone-doubled Fresnel zone plates. These lenses were fabricated by combining electron-beam lithography and atomic layer deposition of iridium. Diffraction efficiencies up to 8% were measured for zone-doubled Fresnel zone plates with an outermost zone width of 25 nm at 6.2-keV photon energy.

  4. Probing plasmons in three dimensions by combining complementary spectroscopies in a scanning transmission electron microscope.

    Hachtel, J A; Marvinney, C; Mouti, A; Mayo, D; Mu, R; Pennycook, S J; Lupini, A R; Chisholm, M F; Haglund, R F; Pantelides, S T

    2016-04-15

    The nanoscale optical response of surface plasmons in three-dimensional metallic nanostructures plays an important role in many nanotechnology applications, where precise spatial and spectral characteristics of plasmonic elements control device performance. Electron energy loss spectroscopy (EELS) and cathodoluminescence (CL) within a scanning transmission electron microscope have proven to be valuable tools for studying plasmonics at the nanoscale. Each technique has been used separately, producing three-dimensional reconstructions through tomography, often aided by simulations for complete characterization. Here we demonstrate that the complementary nature of the two techniques, namely that EELS probes beam-induced electronic excitations while CL probes radiative decay, allows us to directly obtain a spatially- and spectrally-resolved picture of the plasmonic characteristics of nanostructures in three dimensions. The approach enables nanoparticle-by-nanoparticle plasmonic analysis in three dimensions to aid in the design of diverse nanoplasmonic applications. PMID:26934391

  5. Design and performance of a compact scanning transmission X-ray microscope at the Photon Factory.

    Takeichi, Y; Inami, N; Suga, H; Miyamoto, C; Ueno, T; Mase, K; Takahashi, Y; Ono, K

    2016-01-01

    We present a new compact instrument designed for scanning transmission X-ray microscopy. It has piezo-driven linear stages, making it small and light. Optical components from the virtual source point to the detector are located on a single optical table, resulting in a portable instrument that can be operated at a general-purpose spectroscopy beamline without requiring any major reconstruction. Careful consideration has been given to solving the vibration problem common to high-resolution microscopy, so as not to affect the spatial resolution determined by the Fresnel zone plate. Results on bacteriogenic iron oxides, single particle aerosols, and rare-earth permanent magnets are presented as examples of its performance under diverse applications. PMID:26827325

  6. Design and performance of a compact scanning transmission X-ray microscope at the Photon Factory

    Takeichi, Y.; Inami, N.; Suga, H.; Miyamoto, C.; Ueno, T.; Mase, K.; Takahashi, Y.; Ono, K.

    2016-01-01

    We present a new compact instrument designed for scanning transmission X-ray microscopy. It has piezo-driven linear stages, making it small and light. Optical components from the virtual source point to the detector are located on a single optical table, resulting in a portable instrument that can be operated at a general-purpose spectroscopy beamline without requiring any major reconstruction. Careful consideration has been given to solving the vibration problem common to high-resolution microscopy, so as not to affect the spatial resolution determined by the Fresnel zone plate. Results on bacteriogenic iron oxides, single particle aerosols, and rare-earth permanent magnets are presented as examples of its performance under diverse applications.

  7. Imaging Polymer Nanostructures with Scanning Transmission X-ray Spectro-Microscopy

    Full text: Thin polymer films are of increasing technological importance in optoelectronic devices such as LEDs, lasers, FETs and solar cells. However, the morphology of such films is complex and the structure of the polymer film incorporated into a device can strongly affect its performance characteristics, e.g. via the connectedness between of polymer domains and to the device electrodes, or due to anisotropic material properties due to molecular alignment. Scanning transmission x-ray spectro-microscopy (STXM) has been demonstrated to be an excellent tool for the study of organic materials due to its high spatial resolution and strong contrast based on a variety of spectroscopic mechanisms. Recent work at the PolLux STXM has demonstrated a number of new developments, including both hardware upgrades and novel analysis methods. (author)

  8. 4D scanning transmission ultrafast electron microscopy: Single-particle imaging and spectroscopy.

    Ortalan, Volkan; Zewail, Ahmed H

    2011-07-20

    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. PMID:21615171

  9. Stainless Steel Vacuum Chamber for Scanning Transmission X-ray Microsopy

    Kilcoyne, Arthur L.

    2016-07-05

    The stainless steel chamber was specifically conceived and designed for housing an interferometer controlled scanning transmission x-ray microscope (STXM). The construction of the chamber is such that internal components of the microscope rest within the chamber and are fixed to a 4 inch stainless steel belly band. The integral and most important part of the chamber is the belly band, which serves to isolate high frequency vibrations (e.g., floor surroundings, people traffic) from the sensitive measurements performed using the microscope. In addition, the chamber effectively acts as a sound barrier to the nanometer measurements conducted within. The assembled chamber (and microscope) are readily adjustable at the micron level using strut members external to the chamber but fixed to the belly band and a stand made of polymer concreate.

  10. Design and performance of a compact scanning transmission X-ray microscope at the Photon Factory

    Takeichi, Y., E-mail: yasuo.takeichi@kek.jp; Mase, K.; Ono, K. [Institute of Materials Structure Science, High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba 305-0801 (Japan); Department of Materials Structure Science, SOKENDAI (The Graduate University for Advanced Studies), 1-1 Oho, Tsukuba 305-0801 (Japan); Inami, N. [Institute of Materials Structure Science, High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba 305-0801 (Japan); Suga, H. [Department of Earth and Planetary Systems Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526 (Japan); Miyamoto, C. [Department of Earth and Planetary Systems Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku 113-0033 (Japan); Ueno, T. [National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047 (Japan); Takahashi, Y. [Institute of Materials Structure Science, High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba 305-0801 (Japan); Department of Earth and Planetary Systems Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526 (Japan); Department of Earth and Planetary Systems Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku 113-0033 (Japan)

    2016-01-15

    We present a new compact instrument designed for scanning transmission X-ray microscopy. It has piezo-driven linear stages, making it small and light. Optical components from the virtual source point to the detector are located on a single optical table, resulting in a portable instrument that can be operated at a general-purpose spectroscopy beamline without requiring any major reconstruction. Careful consideration has been given to solving the vibration problem common to high-resolution microscopy, so as not to affect the spatial resolution determined by the Fresnel zone plate. Results on bacteriogenic iron oxides, single particle aerosols, and rare-earth permanent magnets are presented as examples of its performance under diverse applications.

  11. New area detector for atomic-resolution scanning transmission electron microscopy.

    Shibata, Naoya; Kohno, Yuji; Findlay, Scott D; Sawada, Hidetaka; Kondo, Yukihito; Ikuhara, Yuichi

    2010-01-01

    A new area detector for atomic-resolution scanning transmission electron microscopy (STEM) is developed and tested. The circular detector is divided into 16 segments which are individually optically coupled with photomultiplier tubes. Thus, 16 atomic-resolution STEM images which are sensitive to the spatial distribution of scattered electrons on the detector plane can be simultaneously obtained. This new detector can be potentially used not only for the simultaneous formation of common bright-field, low-angle annular dark-field and high-angle annular dark-field images, but also for the quantification of images by detecting the full range of scattered electrons and even for exploring novel atomic-resolution imaging modes by post-processing combination of the individual images. PMID:20406732

  12. Probing plasmons in three dimensions in a scanning transmission electron microscope

    Hachtel, Jordan; Mouti, Anas; Mayo, Daniel; Marvinney, Claire; Mu, Richard; Haglund, Richard; Pennycook, Stephen; Chisholm, Matthew; Pantelides, Sokrates

    2015-03-01

    The optical behavior of nanostructured materials is of significant interest across many fields. Surface plasmons and their interactions with emitters in nanoscale devices allow us to control light below the coherence limit. By understanding the nature of plasmonics at the local level we can move towards unlocking the full potential of photonic devices. To this end, we examine plasmonic Ag nanoparticles suspended on insulating nanowires by combining cathodoluminescence spectroscopy, electron energy loss spectroscopy, and high resolution annular dark field imaging in a scanning transmission electron microscope. The complementary nature of CL and EELS allow us to extract optical data from a randomly shaped and oriented nanoparticle, and understand its plasmonic behavior in all three spatial dimensions. This work was sponsored by the US Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division, as well as NSF-EPS-1004083 and NSF-TN-SCORE.

  13. Scanning transmission electron microscopic tomography of cortical bone using Z-contrast imaging.

    McNally, Elizabeth; Nan, Feihong; Botton, Gianluigi A; Schwarcz, Henry P

    2013-06-01

    Previously we presented (McNally et al., 2012) a model for the ultrastructure of bone showing that the mineral resides principally outside collagen fibrils in the form of 5 nm thick mineral structures hundreds of nanometers long oriented parallel to the fibrils. Here we use high-angle annular dark-field electron tomography in the scanning transmission electron microscope to confirm this model and further elucidate the composite structure. Views of a section cut parallel to the fibril axes show bundles of mineral structures extending parallel to the fibrils and encircling them. The mineral density inside the fibrils is too low to be visualized in these tomographic images. A section cut perpendicular to the fibril axes, shows quasi-circular walls composed of mineral structures, wrapping around apparently empty holes marking the sites of fibrils. These images confirm our original model that the majority of mineral in bone resides outside the collagen fibrils. PMID:23545162

  14. Identifying dislocations and stacking faults in GaN films by scanning transmission electron microscopy

    Su, X. J.; Niu, M. T.; Zeng, X. H.; Huang, J.; Zhang, J. C.; Zhang, J. P.; Wang, J. F.; Xu, K.

    2016-08-01

    The application of annular bright field (ABF) and medium-angle annular dark field (MAADF) scanning transmission electron microscopy (STEM) imaging to crystalline defect analysis has been extended to dislocations and stacking faults (SFs). Dislocations and SFs have been imaged under zone-axis and two-beam diffraction conditions. Comparing to conventional two-beam diffraction contrast images, the ABF and MAADF images of dislocations and SFs not only are complementary and symmetrical with their peaks at dislocation core and SFs plane, but also show similar extinction phenomenon. It is demonstrated that conventional TEM rules for diffraction contrast, i.e. g · b and g · R invisibility criteria remain applicable. The contrast mechanism and extinction of dislocation and SFs in ABF and MAADF STEM are illuminated by zero-order Laue zone Kikuchi diffraction.

  15. Design and performance of a compact scanning transmission X-ray microscope at the Photon Factory

    We present a new compact instrument designed for scanning transmission X-ray microscopy. It has piezo-driven linear stages, making it small and light. Optical components from the virtual source point to the detector are located on a single optical table, resulting in a portable instrument that can be operated at a general-purpose spectroscopy beamline without requiring any major reconstruction. Careful consideration has been given to solving the vibration problem common to high-resolution microscopy, so as not to affect the spatial resolution determined by the Fresnel zone plate. Results on bacteriogenic iron oxides, single particle aerosols, and rare-earth permanent magnets are presented as examples of its performance under diverse applications

  16. Scanning Transmission X-ray Microscopy: Applications in Atmospheric Aerosol Research

    Moffet, Ryan C.; Tivanski, Alexei V.; Gilles, Mary K.

    2011-01-20

    Scanning transmission x-ray microscopy (STXM) combines x-ray microscopy and near edge x-ray absorption fine structure spectroscopy (NEXAFS). This combination provides spatially resolved bonding and oxidation state information. While there are reviews relevant to STXM/NEXAFS applications in other environmental fields (and magnetic materials) this chapter focuses on atmospheric aerosols. It provides an introduction to this technique in a manner approachable to non-experts. It begins with relevant background information on synchrotron radiation sources and a description of NEXAFS spectroscopy. The bulk of the chapter provides a survey of STXM/NEXAFS aerosol studies and is organized according to the type of aerosol investigated. The purpose is to illustrate the current range and recent growth of scientific investigations employing STXM-NEXAFS to probe atmospheric aerosol morphology, surface coatings, mixing states, and atmospheric processing.

  17. Non-destructive characterization of CMP pads using scanning ultrasonic transmission

    An automatic scanning ultrasonic transmission (UST) technique was developed and applied to nondestructive metrology and analysis of visco-elastic properties in full-size chemical mechanical planarization (CMP) pads prior to their use in CMP processing. The system is comprised of a specially designed ultrasonic transmitter as an emitter of acoustic vibrations and an ultrasonic probe as a receiver. Both, the transducer and the probe are positioned on the moving X-Z stage, while the circular pad is attached to a rotary motor. The probe is aligned with the center of the transmitter and measures with high accuracy and repeatability the amplitude of the transmitted ultrasonic vibrations through the pad at a pre-selected depth in the pad in the contact mode or at a certain elevation above the surface using non-contact mode. The UST system is computer controlled and fully automated. Inhomogeneity of commercial pads with a diameter up to 32'' were revealed and analyzed. Typical UST map exhibits almost regular stripes of high and low acoustic transmission, which are superimposed with global inhomogeneity where the UST amplitude changes circumferentially. Aside from the UST mapping, the system allows for the study of visco-elastic behavior of pad components using UST transient curves

  18. A high-speed area detector for novel imaging techniques in a scanning transmission electron microscope

    A scanning transmission electron microscope (STEM) produces a convergent beam electron diffraction pattern at each position of a raster scan with a focused electron beam, but recording this information poses major challenges for gathering and storing such large data sets in a timely manner and with sufficient dynamic range. To investigate the crystalline structure of materials, a 16x16 analog pixel array detector (PAD) is used to replace the traditional detectors and retain the diffraction information at every STEM raster position. The PAD, unlike a charge-coupled device (CCD) or photomultiplier tube (PMT), directly images 120-200 keV electrons with relatively little radiation damage, exhibits no afterglow and limits crosstalk between adjacent pixels. Traditional STEM imaging modes can still be performed by the PAD with a 1.1 kHz frame rate, which allows post-acquisition control over imaging conditions and enables novel imaging techniques based on the retained crystalline information. Techniques for rapid, semi-automatic crystal grain segmentation with sub-nanometer resolution are described using cross-correlation, sub-region integration, and other post-processing methods.

  19. Helium Scanning Transmission Ion Microscopy and Electrical Characterization of Glass Nanocapillaries with Reproducible Tip Geometries.

    Zweifel, Ludovit P; Shorubalko, Ivan; Lim, Roderick Y H

    2016-02-23

    Nanopores fabricated from glass microcapillaries are used in applications ranging from scanning ion conductance microscopy to single-molecule detection. Still, evaluating the nanocapillary tip by a noninvasive means remains challenging. For instance, electron microscopy characterization techniques can charge, heat, and contaminate the glass surface and typically require conductive coatings that influence the final tip geometry. Per contra, electrical characterization by the means of ion current through the capillary lumen provides only indirect geometrical details of the tips. Here, we show that helium scanning transmission ion microscopy provides a nondestructive and precise determination of glass nanocapillary tip geometries. This enables the reproducible fabrication of axially asymmetric blunt, bullet, and hourglass-shaped tips with opening diameters from 20 to 400 nm by laser-assisted pulling. Accordingly, this allows for an evaluation of how tip shape, pore diameter, and opening angle impact ionic current rectification behavior and the translocation of single molecules. Our analysis shows that current drops and translocation dwell times are dominated by the pore diameter and opening angles regardless of nanocapillary tip shape. PMID:26783633

  20. Revolving scanning transmission electron microscopy: Correcting sample drift distortion without prior knowledge

    We report the development of revolving scanning transmission electron microscopy – RevSTEM – a technique that enables characterization and removal of sample drift distortion from atomic resolution images without the need for a priori crystal structure information. To measure and correct the distortion, we acquire an image series while rotating the scan coordinate system between successive frames. Through theory and experiment, we show that the revolving image series captures the information necessary to analyze sample drift rate and direction. At atomic resolution, we quantify the image distortion using the projective standard deviation, a rapid, real-space method to directly measure lattice vector angles. By fitting these angles to a physical model, we show that the refined drift parameters provide the input needed to correct distortion across the series. We demonstrate that RevSTEM simultaneously removes the need for a priori structure information to correct distortion, leads to a dramatically improved signal-to-noise ratio, and enables picometer precision and accuracy regardless of drift rate. - Highlights: • We show that capturing a revolving series of STEM images can be used to measure drift parameters. • Lattice vector angles serve as an ideal metric of image distortion during the rotation. • Drift distortion correction can be done without any prior knowledge of the sample structure. • The method is independent of drift rate, and demonstrated using a sample drifting at 0.5 nm/s. • The revolving series enables precise and accurate atom column location information across the entire image

  1. A high-speed area detector for novel imaging techniques in a scanning transmission electron microscope.

    Caswell, T A; Ercius, P; Tate, M W; Ercan, A; Gruner, S M; Muller, D A

    2009-03-01

    A scanning transmission electron microscope (STEM) produces a convergent beam electron diffraction pattern at each position of a raster scan with a focused electron beam, but recording this information poses major challenges for gathering and storing such large data sets in a timely manner and with sufficient dynamic range. To investigate the crystalline structure of materials, a 16x16 analog pixel array detector (PAD) is used to replace the traditional detectors and retain the diffraction information at every STEM raster position. The PAD, unlike a charge-coupled device (CCD) or photomultiplier tube (PMT), directly images 120-200keV electrons with relatively little radiation damage, exhibits no afterglow and limits crosstalk between adjacent pixels. Traditional STEM imaging modes can still be performed by the PAD with a 1.1kHz frame rate, which allows post-acquisition control over imaging conditions and enables novel imaging techniques based on the retained crystalline information. Techniques for rapid, semi-automatic crystal grain segmentation with sub-nanometer resolution are described using cross-correlation, sub-region integration, and other post-processing methods. PMID:19162398

  2. NanoXAS—The in situ Combination of Scanning Transmission X‐ray and Scanning Probe Microscopy

    Schmid, I; J. Raabe; Wenzel, S.; Fink, R; Hug, H; Quitmann, C.

    2012-01-01

    NanoXAS is a novel x‐ray microscope installed at the Swiss Light Source combining laterally resolved soft x‐ray spectroscopy with scanning probe microscopy. We report on first in situ studies from thin polymer blend films and magnetic materials where topographic and spectroscopic contrast are used and show how complementary imaging modes provide new insight into many materials. In the future the scanning probe tip will be used to collect photoelectrons. By this we expect a spatial resolution ...

  3. The effect, identification and correction of misalignment between PET transmission and emission scans on brain PET imaging

    Objectives: To study the effect of misalignment between PET transmission and emission scans of brain on brain PET imaging, and the Methods to identify and correct it. Methods: 18F-FDG PET imaging was performed on 8 volunteers. The emission images were reconstructed with attenuation correction after some translations and rotations in the x-axis and transverse plane were given, 1 mm and 1 degree each step, respectively. The 3-D volume fusion of PET emission and transmission scans was used to identify the suspected misalignment on 10 18F-FDG PET brain imaging. Three Methods were used to correct the misalignment. First, to quantitate the amount of the misalignment by 3-D volume registration of PET emission and transmission scans, the emission images were reconstructed with corrected translations and rotations in x-direction and transverse plane. Second, the emission images were reconstructed with mathematic calculation of brain attenuation. Third, 18F-FDG PET brain imaging was redone with careful application of laser alignment. Results: The translations greater than 3 mm in x-direction and the rotations greater than 8 degrees in transverse plane could lead to visible artifacts, which were presented with decreasing radioactivity uptake in the cortex of half cerebrum and in the frontal cortex at the side in the translating or rotating direction, respectively. The 3-D volume fusion of PET emission and transmission scans could identify and quantitate the amount of misalignment between PET emission and transmission scans of brain. The PET emission images reconstructed with corrected misalignment and mathematic calculation of brain attenuation were consistent with redone PET brain imaging. Conclusions: The misalignment between PET transmission and emission scans of brain can lead to visible artifacts. The 3-D volume fusion of PET emission and transmission scans can identify and quantitate the amount of the misalignment. The visible artifacts caused by the misalignment can be

  4. Development of a scanning transmission x-ray microscope for the beamline P04 at PETRA III DESY

    Andrianov, Konstantin; Ewald, Johannes; Nisius, Thomas; Wilhein, Thomas [Institute for X-Optics, University of Applied Sciences Koblenz-RheinAhrCampus, Joseph-Rovan-Allee 2, 53424 Remagen (Germany); Lühl, Lars; Malzer, Wolfgang; Kanngießer, Birgit [Institute of Optics and Atomic Physics, Technical University of Berlin, Hardenbergstr. 36, 10623 Berlin (Germany)

    2016-01-28

    We present a scanning transmission x-ray microscope (STXM) built on top of our existing modular platform for high resolution imaging experiments. This platform consists of up to three separate vacuum chambers and custom designed piezo stages. These piezo stages are able to move precisely in x-, y- and z-direction, this makes it possible to adjust the components for different imaging modes. During recent experiments the endstation was operated mainly as a transmission x-ray microscope (TXM) [1, 2].

  5. Advanced scanning transmission stereo electron microscopy of structural and functional engineering materials

    Stereo transmission electron microscopy (TEM) provides a 3D impression of the microstructure in a thin TEM foil. It allows to perform depth and TEM foil thickness measurements and to decide whether a microstructural feature lies inside of a thin foil or on its surface. It allows appreciating the true three-dimensional nature of dislocation configurations. In the present study we first review some basic elements of classical stereo TEM. We then show how the method can be extended by working in the scanning transmission electron microscope (STEM) mode of a modern analytical 200 kV TEM equipped with a field emission gun (FEG TEM) and a high angle annular dark field (HAADF) detector. We combine two micrographs of a stereo pair into one anaglyph. When viewed with special colored glasses the anaglyph provides a direct and realistic 3D impression of the microstructure. Three examples are provided which demonstrate the potential of this extended stereo TEM technique: a single crystal Ni-base superalloy, a 9% Chromium tempered martensite ferritic steel and a NiTi shape memory alloy. We consider the effect of camera length, show how foil thicknesses can be measured, and discuss the depth of focus and surface effects. -- Highlights: ► The advanced STEM/HAADF diffraction contrast is extended to 3D stereo-imaging. ► The advantages of the new technique over stereo-imaging in CTEM are demonstrated. ► The new method allows foil thickness measurements in a broad range of conditions. ► We show that features associated with ion milling surface damage can be beneficial for appreciating 3D features of the microstructure.

  6. The scanning transmission x-ray microscope at the NSLS: From XANES to cryo

    The Stony Brook scanning transmission x-ray microscope (STXM) has been operated at the XIA beamline at the NSLS since 1989. A large number of users have used it to study biological and material science samples. The authors report on changes that have been performed in the past year, and present recent results. To stabilize the position of the micro probe when doing spectral scans at high spatial resolution, they have constructed a piezo-driven flexure stage which carries out the focusing motion of the zone plate needed when changing the wavelength. To overcome the detector limitation set by saturation of the gas-flow counter at count rates around 1 MHz, they are installing an avalanche photo diode with an active quenching circuit which they expect to respond linearly to count rates in excess of 10 MHz. They have improved the enclosure for STXM to improve the stability of the Helium atmosphere while taking data. This reduces fluctuations of beam absorption and, therefore, noise in the image. A fast shutter has been installed in the beam line. The authors are also developing a cryo-STXM which is designed for imaging frozen hydrated samples at temperatures below 120 K. At low temperatures, radiation sensitive samples can tolerate a considerably higher radiation dose than at room temperature. This should improve the resolution obtainable from biological samples and should make recording of multiple images of the same sample area possible while minimizing the effects of radiation damage. This should enable them to perform elemental and chemical mapping at high resolution, and to record the large number of views needed for 3D reconstruction of the object

  7. Scanning transmission ion microscopy computed tomography (STIM-CT) for inertial confinement fusion (ICF) targets

    Highlights: ► ICF target quality requires surface finishes on the order of submicron-scale. ► In STIM inner and outer wall profile can be mapped. ► In STIM the thickness and nonconcentricity of shell-wall in ICF targets can be measured. ► STIM-CT is a powerful method for obtaining three-dimensional density maps within ICF targets. ► STIM-CT can obtain internal structure with identifying non-uniformities in the ICF targets. -- Abstract: ICF target quality control in the laser fusion program is vital to ensure that the energy deposition from the lasers results in uniform compression and minimization of Rayleigh–Taylor instabilities, which requires surface finishes on the order of submicron-scale. During target fabrication process the surface finish and the dimensions of the hohlraum need be well controlled. Density variations and nonspherical or nonconcentric shells might be produced. Scanning transmission ion microscopy computed tomography (STIM-CT) is able to reconstruct the three-dimensional quantitative structure of ICF targets a few tens of micrometers in size. Compared to other types of probe techniques, the main advantage of STIM-CT is that quantitative information about mass density and sphericity can be obtained directly and non-destructively, utilizing specific reconstruction codes. We present a case of ICF target (composed of polyvinyl alcohol) characterization by STIM-CT in order to demonstrate the STIM-CT potential impact in assessing target fabrication processes

  8. Characterizing automotive fuel cell materials by soft x-ray scanning transmission x-ray microscopy

    Hitchcock, A. P.; Lee, V.; Wu, J.; West, M. M.; Cooper, G.; Berejnov, V.; Soboleva, T.; Susac, D.; Stumper, J.

    2016-01-01

    Proton-Exchange Membrane Fuel Cell (PEM-FC) based engines are being developed rapidly for near-term implementation in hydrogen fueled, mass production, personal automobiles. Research is focused on understanding and controlling various degradation processes (carbon corrosion, Pt migration, cold start), and reducing cost by reducing or eliminating Pt catalyst. We are using soft X-ray scanning transmission X-ray microscopy (STXM) at the S 2p, C 1s, O 1s and F 1s edges to study a variety of issues related to optimization of PEM-FC materials for automotive applications. A method to efficiently and accurately measure perfluorosulfonic acid distributions was developed and is being used to better understand how different loadings and preparation methods affect the ionomer distribution in the cathode. Progress towards an environmental cell capable of controlling the temperature and humidity of a PEM-FC sample in the STXM is described. Methods for studying the 3D chemical structure of PEM-FC are outlined.

  9. Characterizing automotive fuel cell materials by soft x-ray scanning transmission x-ray microscopy

    Hitchcock, A. P., E-mail: aph@mcmaster.ca; Lee, V.; Wu, J.; Cooper, G. [Chemistry & Chemical Biology, McMaster University, Hamilton, ON, L8S 4M1 (Canada); West, M. M.; Berejnov, V. [Faculty of Health Sciences Electron Microscopy, McMaster University, Hamilton, ON L8N 3Z5 (Canada); Soboleva, T.; Susac, D.; Stumper, J. [Automotive Fuel Cell Cooperation Corp., Burnaby BC V5J 5J8 (Canada)

    2016-01-28

    Proton-Exchange Membrane Fuel Cell (PEM-FC) based engines are being developed rapidly for near-term implementation in hydrogen fueled, mass production, personal automobiles. Research is focused on understanding and controlling various degradation processes (carbon corrosion, Pt migration, cold start), and reducing cost by reducing or eliminating Pt catalyst. We are using soft X-ray scanning transmission X-ray microscopy (STXM) at the S 2p, C 1s, O 1s and F 1s edges to study a variety of issues related to optimization of PEM-FC materials for automotive applications. A method to efficiently and accurately measure perfluorosulfonic acid distributions was developed and is being used to better understand how different loadings and preparation methods affect the ionomer distribution in the cathode. Progress towards an environmental cell capable of controlling the temperature and humidity of a PEM-FC sample in the STXM is described. Methods for studying the 3D chemical structure of PEM-FC are outlined.

  10. Argentinian multi-wavelength scanning Raman lidar to observe night sky atmospheric transmission

    Pallotta, Juan; Otero, Lidia; Chouza, Fernando; Raul, Delia; Gonzalez, Francisco; Etchegoyen, Alberto; Quel, Eduardo

    2013-01-01

    This paper discusses the multi-wavelength scanning Raman lidar being built at Lidar Division, CEILAP (CITEDEF-CONICET) in the frame of the Argentinean Cherenkov Telescope Array (CTA) collaboration to measure the spectral characteristics of the atmospheric aerosol extinction profiles to provide better transmission calculations at the future CTA site. This lidar emits short laser pulses of 7-9 ns at 355, 532 and 1064 nm at 50 Hz with nominal energy of 125 mJ at 1064 nm. This wavelengths are also used to retrieve the atmospheric (air, aerosol and clouds) backscattered radiation in the UV, VIS and IR ranges. Raman capabilities were added in the UV and VIS wavelengths to retrieve the spectral characteristics of the aerosol extinction and the water vapor profile. Due to the expected low aerosol optical depth of the future site, the short observation period as well as the extension of the observation, an enhanced collection area is required. This system uses six 40 cm f/2.5 newtonian telescopes to avoid dealing with...

  11. Rare-earth-doped nanophosphors for multicolor cathodoluminescence nanobioimaging using scanning transmission electron microscopy

    Furukawa, Taichi; Fukushima, Shoichiro; Niioka, Hirohiko; Yamamoto, Naoki; Miyake, Jun; Araki, Tsutomu; Hashimoto, Mamoru

    2015-05-01

    We describe rare-earth-doped nanophosphors (RE-NPs) for biological imaging using cathodoluminescence (CL) microscopy based on scanning transmission electron microscopy (STEM). We report the first demonstration of multicolor CL nanobioimaging using STEM with nanophosphors. The CL spectra of the synthesized nanophosphors (Y2O3:Eu, Y2O3:Tb) were sufficiently narrow to be distinguished. From CL images of RE-NPs on an elastic carbon-coated copper grid, the spatial resolution was beyond the diffraction limit of light. Y2O3:Tb and Y2O3:Eu RE-NPs showed a remarkable resistance against electron beam exposure even at high acceleration voltage (80 kV) and retained a CL intensity of more than 97% compared with the initial intensity for 1 min. In biological CL imaging with STEM, heavy-metal-stained cell sections containing the RE-NPs were prepared, and both the CL images of RE-NPs and cellular structures, such as mitochondria, were clearly observed from STEM images with high contrast. The cellular CL imaging using RE-NPs also had high spatial resolution even though heavy-metal-stained cells are normally regarded as highly scattering media. Moreover, since the RE-NPs exhibit photoluminescence (PL) excited by UV light, they are useful for multimodal correlative imaging using CL and PL.

  12. Characterizing automotive fuel cell materials by soft x-ray scanning transmission x-ray microscopy

    Proton-Exchange Membrane Fuel Cell (PEM-FC) based engines are being developed rapidly for near-term implementation in hydrogen fueled, mass production, personal automobiles. Research is focused on understanding and controlling various degradation processes (carbon corrosion, Pt migration, cold start), and reducing cost by reducing or eliminating Pt catalyst. We are using soft X-ray scanning transmission X-ray microscopy (STXM) at the S 2p, C 1s, O 1s and F 1s edges to study a variety of issues related to optimization of PEM-FC materials for automotive applications. A method to efficiently and accurately measure perfluorosulfonic acid distributions was developed and is being used to better understand how different loadings and preparation methods affect the ionomer distribution in the cathode. Progress towards an environmental cell capable of controlling the temperature and humidity of a PEM-FC sample in the STXM is described. Methods for studying the 3D chemical structure of PEM-FC are outlined

  13. Characterising the surface and interior chemistry of core-shell nanoparticles using scanning transmission electron microscopy

    A method for extracting core and shell spectra from core-shell particles with varying core to shell volume fractions is described. The method extracts the information from a single EELS spectrum image of the particle. The distribution of O and N was correctly reproduced for a nanoparticle with a TiN core and Ti-oxide shell. In addition, the O distribution from a nanoparticle with a Cu core and a Cu-oxide shell was obtained, and the extracted Cu L2,3-core and shell spectra showed the required change in EELS near edge fine structure. The extracted spectra can be used for multiple linear least squares fitting to the raw data in the spectrum image. The effect of certain approximations on numerical accuracy, such as treating the nanoparticle as a perfect sphere, as well as the intrinsic detection limits of the technique have also been explored. The technique is most suitable for qualitative, rather than quantitative, work. -- Research Highlights: → A new method for extracting core and shell EELS spectra from a core-shell nanoparticle is developed. → The technique utilises spectrum imaging in a scanning transmission electron microscope (STEM). → The composition and bonding environment at the core and shell regions can be analysed.→ The method is applied to TiN/Ti-oxide and Cu/Cu-oxide core-shell nanoparticles.→ Numerical accuracy and intrinsic limits of the technique are also discussed.

  14. Common Bias Readout for TES Array on Scanning Transmission Electron Microscope

    Yamamoto, R.; Sakai, K.; Maehisa, K.; Nagayoshi, K.; Hayashi, T.; Muramatsu, H.; Nakashima, Y.; Mitsuda, K.; Yamasaki, N. Y.; Takei, Y.; Hidaka, M.; Nagasawa, S.; Maehata, K.; Hara, T.

    2016-03-01

    A transition edge sensor (TES) microcalorimeter array as an X-ray sensor for a scanning transmission electron microscope system is being developed. The technical challenge of this system is a high count rate of ˜ 5000 counts/second/array. We adopted a 64 pixel array with a parallel readout. Common SQUID bias, and common TES bias are planned to reduce the number of wires and the resources of a room temperature circuit. The reduction rate of wires is 44 % when a 64 pixel array is read out by a common bias of 8 channels. The possible degradation of the energy resolution has been investigated by simulations and experiments. The bias fluctuation effects of a series connection are less than those of a parallel connection. Simple calculations expect that the fluctuations of the common SQUID bias and common TES bias in a series connection are 10^{-7} and 10^{-3} , respectively. We constructed 8 SQUIDs which are connected to 8 TES outputs and a room temperature circuit for common bias readout and evaluated experimentally. Our simulation of crosstalk indicates that at an X-ray event rate of 500 cps/pixel, crosstalk will broaden a monochromatic line by about 0.01 %, or about 1.5 eV at 15 keV. Thus, our design goal of 10 eV energy resolution across the 0.5-15 keV band should be achievable.

  15. Sub-Angstrom metrology of resolution in aberration-corrected transmission electron microscopes using the A-OK standard test specimens

    Allard, Lawrence F.; O' Keefe, Michael A.

    2004-07-01

    Using specimens with diamond cubic and zincblende structures, oriented to provide pairs of atoms in ''dumbbell'' configurations, we have identified specimens with well-characterized atom separations over a 3:1 range of spacings straddling the canonical 1 Angstrom value. Spacings ranging from 1.6 Angstrom to 0.5 Angstrom are available from an ''A-OK'' set of test specimens carefully selected for their stability and well-characterized lattice parameters.

  16. Composition mapping in InGaN by scanning transmission electron microscopy

    We suggest a method for chemical mapping that is based on scanning transmission electron microscopy (STEM) imaging with a high-angle annular dark field (HAADF) detector. The analysis method uses a comparison of intensity normalized with respect to the incident electron beam with intensity calculated employing the frozen lattice approximation. This procedure is validated with an In0.07Ga0.93N layer with homogeneous In concentration, where the STEM results were compared with energy filtered imaging, strain state analysis and energy dispersive X-ray analysis. Good agreement was obtained, if the frozen lattice simulations took into account static atomic displacements, caused by the different covalent radii of In and Ga atoms. Using a sample with higher In concentration and series of 32 images taken within 42 min scan time, we did not find any indication for formation of In rich regions due to electron beam irradiation, which is reported in literature to occur for the parallel illumination mode. Image simulation of an In0.15Ga0.85N layer that was elastically relaxed with empirical Stillinger-Weber potentials did not reveal significant impact of lattice plane bending on STEM images as well as on the evaluated In concentration profiles for specimen thicknesses of 5, 15 and 50 nm. Image simulation of an abrupt interface between GaN and In0.15Ga0.85N for specimen thicknesses up to 200 nm showed that artificial blurring of interfaces is significantly smaller than expected from a simple geometrical model that is based on the beam convergence only. As an application of the method, we give evidence for the existence of In rich regions in an InGaN layer which shows signatures of quantum dot emission in microphotoluminescence spectroscopy experiments. -- Highlights: → Composition mapping in InGaN using quantitative STEM. → No electron beam induced In clustering in InGaN observed for STEM. → Small influence of lattice plane bending for STEM of InGaN/GaN. → In composition

  17. Soft X-ray scanning transmission X-ray microscopy (STXM) of actinide particles.

    Nilsson, Hans J; Tyliszczak, Tolek; Wilson, Richard E; Werme, Lars; Shuh, David K

    2005-09-01

    A descriptive account is given of our most recent research on the actinide dioxides with the Advanced Light Source Molecular Environmental Science (ALS-MES) Beamline 11.0.2 soft X-ray scanning transmission X-ray microscope (STXM) at the Lawrence Berkeley National Laboratory (LBNL). The ALS-MES STXM permits near-edge X-ray absorption fine structure (NEXAFS) and imaging with 30-nm spatial resolution. The first STXM spectromicroscopy NEXAFS spectra at the actinide 4d5/2 edges of the imaged transuranic particles, NpO2 and PuO2, have been obtained. Radiation damage induced by the STXM was observed in the investigation of a mixed oxidation state particle (Np(V,VI)) and was minimized during collection of the actual spectra at the 4d5/2 edge of the Np(V,VI) solid. A plutonium elemental map was obtained from an irregular PuO2 particle with the dimensions of 650 x 650 nm. The Pu 4d5/2 NEXAFS spectra were collected at several different locations from the PuO2 particle and were identical. A representative oxygen K-edge spectrum from UO2 was collected and resembles the oxygen K-edge from the bulk material. The unique and current performance of the ALS-MES STXM at extremely low energies (ca. 100 eV) that may permit the successful measurement of the actinide 5d edge is documented. Finally, the potential of STXM as a tool for actinide investigations is briefly discussed. PMID:16021423

  18. Atom location using scanning transmission electron microscopy based on electron energy loss spectroscopy

    Full text: The technique of atom location by channelling enhanced microanalysis (ALCHEMI) using cross section data, measured as a function of electron beam orientation, has been widely implemented by many researchers. The accurate application of ALCHEMI, usually based on energy dispersive x-ray analysis (EDX), requires knowledge, from first principles, of the relative delocalization of the inner-shell ionization interaction (see for example Oxley and Allen, 1998; Oxley et al., 1999). Scanning transmission electron microscopy (STEM) based on electron energy loss spectroscopy (EELS) also provides information about the location of atoms of different types within the crystal lattice. Unlike high angle annular dark field (HAADF), EELS provides a unique signal for each atom type. In conjunction with highly focused probes, allowing near atomic resolution, this makes possible, in principle, the application of ALCHEMI like techniques to STEM images to determine the distribution of impurities within the unit cell. The accurate interpretation of STEM results requires that both the inner-shell ionization interaction and resulting ionization cross section or image be correctly modelled. We present model calculations demonstrating the in principle application of ALCHEMI type techniques to STEM images pertinent to EELS. The inner-shell ionisation interaction is modelled using Hartree-Fock wave functions to describe the atomic bound states and Hartree-Slater wave functions to describe the continuum states. The wave function within the crystal is calculated using boundary conditions appropriate for a highly focussed probe (Rossouw and Allen, 2001) and STEM images or ionisation cross sections are simulated using an inelastic cross section formulation that correctly accounts for the contribution from both dynamical electrons and those dechannelled by absorptive scattering processes such as thermal diffuse scattering (TDS). Copyright (2002) Australian Society for Electron Microscopy

  19. Analysis of environmental particles by atomic force microscopy, scanning and transmission electron microscopy.

    Mavrocordatos, D; Pronk, W; Boiler, M

    2004-01-01

    Due to their large specific surface and their abundance, micro and nano particles play an important role in the transport of micropollutants in the environment. Natural particles are usually composed of a mixture of inorganic amorphous or crystalline material (mainly FeOOH, Fe(x)Oy, Mn(x)Oy and clays) and organic material (humics and polysaccharides). They all tend to occur as very small particles (1-1,000 nm in diameter). Most natural amorphous particles are unstable and tend to transform with time towards more crystalline forms, either by aging or possibly, by dissolution and re-crystallization. Such transformations affect the fate of sorbed micropollutants and the scavenging properties are therefore changed. As these entities are sensitive to dehydration (aggregation, changes in the morphology), it is highly important to observe their morphology in their natural environment and understand their composition at the scale of the individual particles. Also for the understanding and optimization of water treatment technologies, the knowledge of the occurrence and behavior of nano-particles is of high importance. Some of the possible particle analysis methods are presented: aggregation processes, biomineralization, bacterial adhesion, biofilms in freshwaters, ferrihydrite as heavy metals remover from storm water. These examples demonstrate the capabilities and focus of the microscopes. Atomic Force Microscopy (AFM) allows to analyze the particles in their own environment, meaning in air or in the water. Thus, native aspects of particles can be observed. As well, forces of interactions between particles or between particles and other surfaces such as membranes will be highly valuable data. Scanning Electron Microscopy (SEM) and for higher lateral resolution, Transmission Electron Microscopy (TEM) allow measurement of the morphology and composition. Especially, TEM coupled with Electron Energy Loss Spectroscopy (TEM-EELS) is a powerful technique for elemental analysis

  20. Morphology and ultrastructure of Brachymystax lenok tsinlingensis spermatozoa by scanning and transmission electron microscopy.

    Guo, Wei; Shao, Jian; Li, Ping; Wu, Jinming; Wei, Qiwei

    2016-08-01

    This study was conducted to investigate Brachymystax lenok tsinlingensis spermatozoa cell morphology and ultrastructure through scanning and transmission electron microscopy. Findings revealed that the spermatozoa can be differentiated into three major parts: a spherical head without an acrosome, a short mid-piece, and a long, cylindrical flagellum. The mean length of the spermatozoa was 36.11±2.84μm, with a spherical head length of 2.78±0.31μm. The mean anterior and posterior head widths were 2.20±0.42μm and 2.55±0.53μm, respectively. The nuclear fossa was positioned at the base of the nucleus that contained the anterior portion of flagellum and a centriolar complex (proximal and distal centrioles). The short mid-piece was located laterally to the nucleus and possessed just one spherical mitochondrion with a mean diameter of 0.65±0.14μm. The spermatozoa flagellum was long and cylindrical, and could be separated into two parts: a long main-piece and a short end-piece. The main piece of the flagellum had short irregular side-fins. The axoneme composed the typical '9+2' microtubular doublet structure and was enclosed by the cell membran e. This study confirmed that B. lenok tsinlingensis spermatozoa can be categorized as teleostean "Type I" spermatozoa; 'primitive' or 'ect-aquasperm type' spermatozoa. To the best of the authers knowledge, this was the first study conducted on the morphology and ultrastructure of B. lenok tsinlingensis spermatozoa. PMID:27375213

  1. 3-d chemical imaging using angle-scan nanotomography in a soft X-ray scanning transmission X-ray microscope

    Three-dimensional chemical mapping using angle scan nanotomography in a soft X-ray scanning transmission X-ray microscope (STXM) has been used to investigate the spatial distributions of a low density polyacrylate polyelectrolyte ionomer inside submicron sized polystyrene microspheres. Acquisition of tomograms at multiple photon energies provides true, quantifiable 3-d chemical sensitivity. Both pre-O 1s and C 1s results are shown. The study reveals aspects of the 3-d distribution of the polyelectrolyte that were inferred indirectly or had not been known prior to this study. The potential and challenges for extension of the technique to studies of other polymeric and to biological systems is discussed. (orig.)

  2. Construction of a scanning transmission X-ray microscope at the undulator U-41 at BESSY II

    Wiesemann, U; Frueke, R; Guttmann, P; Niemann, B; Rudolph, D; Schmahl, G

    2001-01-01

    A new scanning transmission X-ray microscope for the soft X-ray region is under construction at the BESSY II storage ring. The radiation from the undulator U-41 is monochromatized with a monochromator consisting of a plane mirror and a plane grating with varied line density. For a high resolution image, the zone plate is scanned with a piezoelectric flexure stage. The X-ray flux in the focal spot will be of the order of 10 sup 9 photons/s. The sample is located in air. A pn-CCD detector is used to measure the transmitted intensity.

  3. Simultaneous fluorescence and high-resolution bright-field imaging with aberration correction over a wide field-of-view with Fourier ptychographic microscopy (FPM) (Conference Presentation)

    Chung, Jaebum; Kim, Jinho; Ou, Xiaoze; Horstmeyer, Roarke; Yang, Changhuei

    2016-03-01

    We present a method to acquire both fluorescence and high-resolution bright-field images with correction for the spatially varying aberrations over a microscope's wide field-of-view (FOV). First, the procedure applies Fourier ptychographic microscopy (FPM) to retrieve the amplitude and phase of a sample, at a resolution that significantly exceeds the cutoff frequency of the microscope objective lens. At the same time, FPM algorithm is able to leverage on the redundancy within the set of acquired FPM bright-field images to estimate the microscope aberrations, which usually deteriorate in regions further away from the FOV's center. Second, the procedure acquires a raw wide-FOV fluorescence image within the same setup. Lack of moving parts allows us to use the FPM-estimated aberration map to computationally correct for the aberrations in the fluorescence image through deconvolution. Overlaying the aberration-corrected fluorescence image on top of the high-resolution bright-field image can be done with accurate spatial correspondence. This can provide means to identifying fluorescent regions of interest within the context of the sample's bright-field information. An experimental demonstration successfully improves the bright-field resolution of fixed, stained and fluorescently tagged HeLa cells by a factor of 4.9, and reduces the error caused by aberrations in a fluorescence image by 31%, over a field of view of 6.2 mm by 9.3 mm. For optimal deconvolution, we show the fluorescence image needs to have a signal-to-noise ratio of ~18.

  4. IN VITRO ACTION OF COBRA VENOM ON GOAT SPERMATOZOA ULTRASTRUCTURE BY TRANSMISSION AND SCANNING ELECTRON MICROSCOPY

    T. R. RAHMY

    2002-01-01

    Full Text Available Goat spermatozoa were incubated in vitro in Tris-citrate buffer, pH 7.2, containing 0, 40, 80, or 160 mug of Naja haje venom/mL buffer for 4 hours. During incubation, the percentages of sperm motility were decreased, while percentages of dead spermatozoa were increased in a time and concentration-dependent manner. The effect of venom concentrations on the ultrastructure of incubated spermatozoa was examined hourly by scanning (SEM and transmission (TEM electron microscopy. SEM results showed plasma membrane wrinkling at heads of some spermatozoa after 2 h incubation with 40mug venom. Most spermatozoa suffered membrane wrinkling after 4 h incubation. However, incubation with 80 mug venom caused membrane fractures in most sperm heads after 1 h incubation. The extent and depth of these fractures were increased after 2-3 h incubation. After 4 h incubation, plasma membrane focal erosion of many spermatozoa heads was common. Incubation with 160 mg venom induced sperm head swollen plasma membranes after 1 h incubation. Ruptured and disintegrated membranes were seen after 2 h; lysis and removal of external surface of spermatozoa head plasma membranes were recorded after 3-4 h incubation. TEM indicated slightly swollen areas on the sperm head plasma membrane, but showed normal nuclei, acrosomes, and tail regions after 2 h incubation in 40 mug cobra venom. The swollen areas were accompanied by sperm head membrane disintegration as well as membrane irregularities and distortion of tail mitochondrial cristae after 3-4 h incubation. However, incubation with 80 mug venom showed focal areas of membrane lysis and discontinuity in the sperm heads and tails increasing with incubation time. Severe axoneme and tail longitudinal fiber degeneration and increased numbers of distorted mitochondrial cristae were also observed after 3-4 h incubation. Spermatozoa incubation with 160 mug venom increased severity of plasma membrane dissolution, disintegration, and rupture

  5. Automated Transmission-Mode Scanning Electron Microscopy (tSEM) for Large Volume Analysis at Nanoscale Resolution

    Kuwajima, Masaaki; Mendenhall, John M.; Lindsey, Laurence F.; Harris, Kristen M.

    2013-01-01

    Transmission-mode scanning electron microscopy (tSEM) on a field emission SEM platform was developed for efficient and cost-effective imaging of circuit-scale volumes from brain at nanoscale resolution. Image area was maximized while optimizing the resolution and dynamic range necessary for discriminating key subcellular structures, such as small axonal, dendritic and glial processes, synapses, smooth endoplasmic reticulum, vesicles, microtubules, polyribosomes, and endosomes which are critic...

  6. A pulsated weak-resonant-cavity laser diode with transient wavelength scanning and tracking for injection-locked RZ transmission.

    Lin, Gong-Ru; Chi, Yu-Chieh; Liao, Yu-Sheng; Kuo, Hao-Chung; Liao, Zhi-Wang; Wang, Hai-Lin; Lin, Gong-Cheng

    2012-06-18

    By spectrally slicing a single longitudinal-mode from a master weak-resonant-cavity Fabry-Perot laser diode with transient wavelength scanning and tracking functions, the broadened self-injection-locking of a slave weak-resonant-cavity Fabry-Perot laser diode is demonstrated to achieve bi-directional transmission in a 200-GHz array-waveguide-grating channelized dense-wavelength-division-multiplexing passive optical network system. Both the down- and up-stream slave weak-resonant-cavity Fabry-Perot laser diodes are non-return-to-zero modulated below threshold and coherently injection-locked to deliver the pulsed carrier for 25-km bi-directional 2.5 Gbits/s return-to-zero transmission. The master weak-resonant-cavity Fabry-Perot laser diode is gain-switched at near threshold condition and delivers an optical coherent pulse-train with its mode linewidth broadened from 0.2 to 0.8 nm by transient wavelength scanning, which facilitates the broadband injection-locking of the slave weak-resonant-cavity Fabry-Perot laser diodes with a threshold current reducing by 10 mA. Such a transient wavelength scanning induced spectral broadening greatly releases the limitation on wavelength injection-locking range required for the slave weak-resonant-cavity Fabry-Perot laser diode. The theoretical modeling and numerical simulation on the wavelength scanning and tracking effects of the master and slave weak-resonant-cavity Fabry-Perot laser diodes are performed. The receiving power sensitivity for back-to-back transmission at bit-error-rate transmission is less than 2 dB for all 16 channels. PMID:22714427

  7. Dark-Field Scanning Transmission Ion Microscopy via Detection of Forward-Scattered Helium Ions with a Microchannel Plate.

    Woehl, Taylor J; White, Ryan M; Keller, Robert R

    2016-06-01

    A microchannel plate was used as an ion sensitive detector in a commercial helium ion microscope (HIM) for dark-field transmission imaging of nanomaterials, i.e. scanning transmission ion microscopy (STIM). In contrast to previous transmission HIM approaches that used secondary electron conversion holders, our new approach detects forward-scattered helium ions on a dedicated annular shaped ion sensitive detector. Minimum collection angles between 125 mrad and 325 mrad were obtained by varying the distance of the sample from the microchannel plate detector during imaging. Monte Carlo simulations were used to predict detector angular ranges at which dark-field images with atomic number contrast could be obtained. We demonstrate atomic number contrast imaging via scanning transmission ion imaging of silica-coated gold nanoparticles and magnetite nanoparticles. Although the resolution of STIM is known to be degraded by beam broadening in the substrate, we imaged magnetite nanoparticles with high contrast on a relatively thick silicon nitride substrate. We expect this new approach to annular dark-field STIM will open avenues for more quantitative ion imaging techniques and advance fundamental understanding of underlying ion scattering mechanisms leading to image formation. PMID:27153003

  8. A new approach to analysing HST spatial scans: the transmission spectrum of HD 209458b

    Tsiaras, A; Rocchetto, M; Varley, R; Morello, G; Tinetti, G

    2015-01-01

    The Wide Field Camera 3 (WFC3) on Hubble Space Telescope (HST) is currently one of the most popular instruments for observing exoplanetary atmospheres, especially with the use of the spatial scanning technique. An increasing number of exoplanets have been studied using this technique as it enables the observation of bright targets without saturating the sensitive detectors. In this work we present a new pipeline for analysing the data obtained with the spatial scanning technique, starting from the raw data provided by the instrument. In addition to commonly used correction techniques, we take into account the geometric distortions of the instrument, whose impact may become important when combined to the scanning process. Our approach can improve the photometric precision for existing data and also push further the limits of the spatial scanning technique, as it allows the analysis of even longer spatial scans. As an application of our method and pipeline, we present the results from a reanalysis of the spatia...

  9. Structural characterization of interfaces in epitaxial Fe/MgO/Fe magnetic tunnel junctions by transmission electron microscopy

    We present a detailed structural characterization of the interfaces in Fe/MgO/Fe layers grown by molecular-beam epitaxy using aberration-corrected transmission electron microscopy (TEM), scanning TEM, and electron energy-loss spectroscopy. When fabricated into magnetic tunnel junctions, these epitaxial devices exhibit large tunnel magnetoresistance ratios (e.g., 318% at 10 K), though still considerably lower than the values predicted theoretically. The reason for this discrepancy is being debated and has been attributed to the structure of, and defects at the interface, namely, the relative position of the atoms, interface oxidation, strain, and structural asymmetry of the interfaces. In this structural study, we observed that Fe is bound to O at the interfaces. The interfaces are semicoherent and mostly sharp with a minor degree of oxidation. A comparison of the two interfaces shows that the top MgO/Fe interface is rougher.

  10. Fast two-dimensional grid and transmission X-ray microscopy scanning methods for visualizing and characterizing protein crystals

    Wojdyla, Justyna Aleksandra; Panepucci, Ezequiel; Martiel, Isabelle; Ebner, Simon; Huang, Chia-Ying; Caffrey, Martin; Bunk, Oliver; Wang, Meitian

    2016-01-01

    A fast continuous grid scan protocol has been incorporated into the Swiss Light Source (SLS) data acquisition and analysis software suite on the macromolecular crystallography (MX) beamlines. Its combination with fast readout single-photon counting hybrid pixel array detectors (PILATUS and EIGER) allows for diffraction-based identification of crystal diffraction hotspots and the location and centering of membrane protein microcrystals in the lipid cubic phase (LCP) in in meso in situ serial crystallography plates and silicon nitride supports. Diffraction-based continuous grid scans with both still and oscillation images are supported. Examples that include a grid scan of a large (50 nl) LCP bolus and analysis of the resulting diffraction images are presented. Scanning transmission X-ray microscopy (STXM) complements and benefits from fast grid scanning. STXM has been demonstrated at the SLS beamline X06SA for near-zero-dose detection of protein crystals mounted on different types of sample supports at room and cryogenic temperatures. Flash-cooled crystals in nylon loops were successfully identified in differential and integrated phase images. Crystals of just 10 µm thickness were visible in integrated phase images using data collected with the EIGER detector. STXM offers a truly low-dose method for locating crystals on solid supports prior to diffraction data collection at both synchrotron microfocusing and free-electron laser X-ray facilities. PMID:27275141

  11. EVALUATION OF THE ULTRASTRUCTURE OF THE SMALL INTESTINE OF HIV INFECTED CHILDREN BY TRANSMISSION AND SCANNING ELECTRONIC MICROSCOPY

    Christiane Araujo Chaves LEITE

    2013-03-01

    Full Text Available Objectives To describe HIV children's small intestinal ultrastructural findings. Methods Descriptive, observational study of small intestine biopsies performed between August 1994 and May 1995 at São Paulo, SP, Brazil. This material pertained to 11 HIV infected children and was stored in a laboratory in paraffin blocks. Scanning and transmission electronic microscopy were used to view those intestine samples and ultrastructural findings were described by analyzing digitalized photos of this material. Ethical Committee approval was obtained. Results In most samples scanning microscopy showed various degrees of shortening and decreasing number of microvilli and also completes effacements in some areas. Derangement of the enterocytes was seen frequently and sometimes cells well defined borders limits seemed to be loosened. In some areas a mucous-fibrin like membrane with variable thickness and extension appeared to partially or totally coat the epithelial surface. Fat drops were present in the intestinal lumen in various samples and a bacterium morphologically resembling bacilli was seen in two occasions. Scanning microscopy confirmed transmission microscopy microvilli findings and also showed little “tufts” of those structures. In addition, it showed an increased number of vacuoles and multivesicular bodies inside various enterocytes, an increased presence of intraepithelial lymphocytes, mitochondrial vacuolization and basement membrane enlargement in the majority of samples analyzed. However, some samples exhibited normal aspect. Conclusions Our study showed the common occurrence of various important intestinal ultrastructural alterations with variable degrees among HIV infected children, some of them in our knowledge not described before.

  12. Determination of the cork bark porosity through the gamma ray transmission technology and electronic scanning microscopy image analysis

    This work applies the gamma transmission techniques (GTR) and imaging by scanning electron microscopy (SEM) for determination of porosity in the sparkling wine bottle corks. The gamma transmission experimental apparatus consists of a micrometric table (ZX) of sample movement automated, a Am-241 source (59,53 keV, 100 mCi), lead collimators, sample-holder, Na I(Tl) detector and appropriated electronics. For the microscopic images an FEI (Quanta 200), electronic microscope with associated electronics was used, and the image analysis was performed with IMAGO software. The average porosity for 22 samples analysed by GTR was of φ=58 +- 4.6 percent. By the imaging technique the found average porosity was φ=60.0 +- 6.2 percent. (author)

  13. A new bend magnet beam line for scanning transmission x-ray microscopy at the Advanced Light Source

    Warwick, Tony; Ade, Harald; Kilcoyne, A.L. David; Kritscher, Michael; Tylisczcak, Tolek; Fakra, Sirine; Hitchcock, Adam P.; Hitchcock, Peter; Padmore, Howard A.

    2001-12-12

    The high brightness of the bend magnets at the Advanced Light Source has been exploited to illuminate a Scanning Transmission X-ray Microscope (STXM). This is the first diffraction-limited scanning x-ray microscope to operate with useful count rate on a synchrotron bend magnet source. A simple, dedicated beam line has been built covering the range of photon energy from 250 eV to 600 eV. Ease of use and operational availability are radically improved compared to previous installations using undulator beams. This facility provides radiation for C 1s, N 1s and O 1s near edge x-ray absorption spectro-microscopy with a spectral resolution up to about 1:5000 and with STXM count rates in excess of 1 MHz.

  14. Characterizing deformed ultrafine-grained and nanocrystalline materials using transmission Kikuchi diffraction in a scanning electron microscope

    Graphical abstract: -- Abstract: The recent development of transmission Kikuchi diffraction (TKD) in a scanning electron microscope enables fast, automated orientation mapping of electron transparent samples using standard electron backscatter diffraction (EBSD) hardware. TKD in a scanning electron microscope has significantly better spatial resolution than conventional EBSD, enabling routine characterization of nanocrystalline materials and allowing effective measurement of samples that have undergone severe plastic deformation. Combining TKD with energy dispersive X-ray spectroscopy (EDS) provides complementary chemical information, while a standard forescatter detector system below the EBSD detector can be used to generate dark field and oriented dark field images. Here we illustrate the application of this exciting new approach to a range of deformed, ultrafine grained and nanocrystalline samples, including duplex stainless steel, nanocrystalline copper and highly deformed titanium and nickel–cobalt. The results show that TKD combined with EDS is a highly effective and widely accessible tool for measuring key microstructural parameters at resolutions that are inaccessible using conventional EBSD

  15. Probing the electronic structure of graphene sheets with various thicknesses by scanning transmission X-ray microscopy

    Bai, Lili; Liu, Jinyin; Zhao, Guanqi; Gao, Jing; Sun, Xuhui, E-mail: xhsun@suda.edu.cn, E-mail: jzhong@suda.edu.cn; Zhong, Jun, E-mail: xhsun@suda.edu.cn, E-mail: jzhong@suda.edu.cn [Soochow University-Western University Centre for Synchrotron Radiation Research, Institute of Functional Nano and Soft Materials Laboratory (FUNSOM) and Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215123 (China)

    2013-12-16

    The electronic structure of an aggregation of graphene sheets with various thicknesses was probed by scanning transmission X-ray microscopy. A uniform oxidation of the graphene sheets in the flat area was observed regardless of the thickness, while in the folded area the result could be strongly affected by the geometry. Moreover, thick parts of the aggregation showed strong angle-dependence to the incident X-ray, while thin parts showed less angle-dependence, which might be related to the surface wrinkles and ripples. The electronic structure differences due to the geometry and thickness suggest a complicated situation in the aggregation of graphene sheets.

  16. Largely defocused probe scanning transmission electron microscopy for imaging local modulation of strain field in a hetero interface

    Kim, Suhyun, E-mail: u98kim@surface.phys.titech.ac.jp; Jung, Younheum; Kim, Joong Jung; Lee, Sunyoung; Lee, Haebum [Memory Analysis Science and Engineering Group, Samsung Electronics, San #16 Hwasung-City, Gyeonggi-Do 445-701 (Korea, Republic of); Oshima, Yoshifumi [School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292 (Japan)

    2014-10-13

    We present an innovative method for characterizing the strain field in three dimensions in a hetero interface. Largely defocused probe scanning transmission electron microscopy (LDP-STEM) was employed for imaging the inhomogeneous strain field in a germanium (Ge) layer deposited on a silicon (Si) substrate. In the LDP-STEM image, Ge-atomic columns that are relaxed or strained to the Si substrate in the Si/Ge hetero interface were observed to be distinguishable, allowing for the qualitative characterization of the coherency of the crystal growth. Our results revealed that the strain field is locally modulated along the in-plane direction in the Si/Ge hetero interface.

  17. Energy dispersive X-ray analysis on an absolute scale in scanning transmission electron microscopy

    We demonstrate absolute scale agreement between the number of X-ray counts in energy dispersive X-ray spectroscopy using an atomic-scale coherent electron probe and first-principles simulations. Scan-averaged spectra were collected across a range of thicknesses with precisely determined and controlled microscope parameters. Ionization cross-sections were calculated using the quantum excitation of phonons model, incorporating dynamical (multiple) electron scattering, which is seen to be important even for very thin specimens. - Highlights: • Scan-averaged energy dispersive X-ray (EDX) spectra are recorded in STEM. • Experimental and simulated EDX signals are shown to agree on an absolute scale. • Two independent methods are used for accurate thickness determination. • Probe channelling must be taken into account, even for very thin specimens. • Channelling effects are minimized for large probe-forming convergence angles

  18. Energy dispersive X-ray analysis on an absolute scale in scanning transmission electron microscopy

    Chen, Z. [School of Physics and Astronomy, Monash University, Clayton, Victoria 3800 (Australia); D' Alfonso, A.J. [School of Physics, University of Melbourne, Parkville, Victoria 3010 (Australia); Weyland, M. [Monash Centre for Electron Microscopy, Monash University, Clayton, Victoria 3800 (Australia); Department of Materials Science and Engineering, Monash University, Clayton, Victoria 3800 (Australia); Taplin, D.J. [School of Physics and Astronomy, Monash University, Clayton, Victoria 3800 (Australia); Allen, L.J. [School of Physics, University of Melbourne, Parkville, Victoria 3010 (Australia); Findlay, S.D., E-mail: scott.findlay@monash.edu [School of Physics and Astronomy, Monash University, Clayton, Victoria 3800 (Australia)

    2015-10-15

    We demonstrate absolute scale agreement between the number of X-ray counts in energy dispersive X-ray spectroscopy using an atomic-scale coherent electron probe and first-principles simulations. Scan-averaged spectra were collected across a range of thicknesses with precisely determined and controlled microscope parameters. Ionization cross-sections were calculated using the quantum excitation of phonons model, incorporating dynamical (multiple) electron scattering, which is seen to be important even for very thin specimens. - Highlights: • Scan-averaged energy dispersive X-ray (EDX) spectra are recorded in STEM. • Experimental and simulated EDX signals are shown to agree on an absolute scale. • Two independent methods are used for accurate thickness determination. • Probe channelling must be taken into account, even for very thin specimens. • Channelling effects are minimized for large probe-forming convergence angles.

  19. Scanning transmission ion microscopy (STIM) with a 3 MeV proton cyclotron beam

    Maanen, I.F. van [Technische Univ., Eindhoven (Netherlands). Cyclotron Lab.; Mutsaers, P.H.A. [Technische Univ., Eindhoven (Netherlands). Cyclotron Lab.; Verhoef, B.A.W. [Technische Univ., Eindhoven (Netherlands). Cyclotron Lab.; Voigt, M.J.A. de [Technische Univ., Eindhoven (Netherlands). Cyclotron Lab.

    1996-06-01

    A method is developed to optimize the lateral resolution of a scanning proton microprobe using a 3 MeV cyclotron beam. The most important part of the method is the optimization of an asymmetrical quadrupole quadruplet, based on second-order relationships between diaphragm widths and the full width of the spot. A STIM example is presented of cellular structures of rat-heart tissue. (orig.).

  20. Scanning transmission ion microscopy (STIM) with a 3 MeV proton cyclotron beam

    A method is developed to optimize the lateral resolution of a scanning proton microprobe using a 3 MeV cyclotron beam. The most important part of the method is the optimization of an asymmetrical quadrupole quadruplet, based on second-order relationships between diaphragm widths and the full width of the spot. A STIM example is presented of cellular structures of rat-heart tissue. (orig.)

  1. Analysis of self-organized In(Ga)As quantum structures with the scanning transmission electron microscope

    Aim of this thesis was to apply the analytical methods of the scanning transmission electron microscopy to the study of self-organized In(Ga)As quantum structures. With the imaging methods Z contrast and bright field (position resolutions in the subnanometer range) and especially with the possibilities of the quantitative chemical EELS analysis of the scanning transmission electron microscope (STEM) fundamental questions concerning morphology and chemical properties of self-organized quantum structures should be answered. By the high position resolution of the STEM among others essentail morphological and structural parameters in the growth behaviour of ''dot in a well'' (DWell) structures and of vertically correlated quantum dots (QDs) could be analyzed. For the optimization of DWell structures samples were studied, the nominal InAs-QD growth position was directedly varied within the embedding InGaAs quantum wells. The STEM offers in connection with the EELS method a large potential for the chemical analysis of quantum structures. Studied was a sample series of self-organized InGaAs/GaAs structures on GaAs substrate, the stress of which was changed by varying the Ga content of the INGaAs material between 2.4 % and 4.3 %

  2. Automated transmission-mode scanning electron microscopy (tSEM for large volume analysis at nanoscale resolution.

    Masaaki Kuwajima

    Full Text Available Transmission-mode scanning electron microscopy (tSEM on a field emission SEM platform was developed for efficient and cost-effective imaging of circuit-scale volumes from brain at nanoscale resolution. Image area was maximized while optimizing the resolution and dynamic range necessary for discriminating key subcellular structures, such as small axonal, dendritic and glial processes, synapses, smooth endoplasmic reticulum, vesicles, microtubules, polyribosomes, and endosomes which are critical for neuronal function. Individual image fields from the tSEM system were up to 4,295 µm(2 (65.54 µm per side at 2 nm pixel size, contrasting with image fields from a modern transmission electron microscope (TEM system, which were only 66.59 µm(2 (8.160 µm per side at the same pixel size. The tSEM produced outstanding images and had reduced distortion and drift relative to TEM. Automated stage and scan control in tSEM easily provided unattended serial section imaging and montaging. Lens and scan properties on both TEM and SEM platforms revealed no significant nonlinear distortions within a central field of ∼100 µm(2 and produced near-perfect image registration across serial sections using the computational elastic alignment tool in Fiji/TrakEM2 software, and reliable geometric measurements from RECONSTRUCT™ or Fiji/TrakEM2 software. Axial resolution limits the analysis of small structures contained within a section (∼45 nm. Since this new tSEM is non-destructive, objects within a section can be explored at finer axial resolution in TEM tomography with current methods. Future development of tSEM tomography promises thinner axial resolution producing nearly isotropic voxels and should provide within-section analyses of structures without changing platforms. Brain was the test system given our interest in synaptic connectivity and plasticity; however, the new tSEM system is readily applicable to other biological systems.

  3. Automated transmission-mode scanning electron microscopy (tSEM) for large volume analysis at nanoscale resolution.

    Kuwajima, Masaaki; Mendenhall, John M; Lindsey, Laurence F; Harris, Kristen M

    2013-01-01

    Transmission-mode scanning electron microscopy (tSEM) on a field emission SEM platform was developed for efficient and cost-effective imaging of circuit-scale volumes from brain at nanoscale resolution. Image area was maximized while optimizing the resolution and dynamic range necessary for discriminating key subcellular structures, such as small axonal, dendritic and glial processes, synapses, smooth endoplasmic reticulum, vesicles, microtubules, polyribosomes, and endosomes which are critical for neuronal function. Individual image fields from the tSEM system were up to 4,295 µm(2) (65.54 µm per side) at 2 nm pixel size, contrasting with image fields from a modern transmission electron microscope (TEM) system, which were only 66.59 µm(2) (8.160 µm per side) at the same pixel size. The tSEM produced outstanding images and had reduced distortion and drift relative to TEM. Automated stage and scan control in tSEM easily provided unattended serial section imaging and montaging. Lens and scan properties on both TEM and SEM platforms revealed no significant nonlinear distortions within a central field of ∼100 µm(2) and produced near-perfect image registration across serial sections using the computational elastic alignment tool in Fiji/TrakEM2 software, and reliable geometric measurements from RECONSTRUCT™ or Fiji/TrakEM2 software. Axial resolution limits the analysis of small structures contained within a section (∼45 nm). Since this new tSEM is non-destructive, objects within a section can be explored at finer axial resolution in TEM tomography with current methods. Future development of tSEM tomography promises thinner axial resolution producing nearly isotropic voxels and should provide within-section analyses of structures without changing platforms. Brain was the test system given our interest in synaptic connectivity and plasticity; however, the new tSEM system is readily applicable to other biological systems. PMID:23555711

  4. A new Scanning Transmission X-ray Microscope at the ALS for operation up to 2500eV

    We report on the design and construction of a higher energy Scanning Transmission X-ray Microscope on a new bend magnet beam line at the Advanced Light Source. Previously we have operated such an instrument on a bend magnet for C, N and O 1s NEXAFS spectroscopy. The new instrument will have similar performance at higher energies up to and including the S 1s edge at 2472eV. A new microscope configuration is planned. A more open geometry will allow a fluorescence detector to count emitted photons from the front surface of the sample. There will be a capability for zone plate scanning in addition to the more conventional sample scanning mode. This will add the capability for imaging a massive sample at high resolution over a limited field of view, so that heavy reaction cells may be used to study processes in-situ, exploiting the longer photon attenuation length and the longer zone plate working distances available at higher photon energy. The energy range will extend down to include the C1s edge at 300eV, to allow high energy NEXAFS microscopic studies to correlate with the imaging of organics in the same sample region of interest.

  5. Lung scan accuracy and precision in the diagnosis of pulmonary embolism by transmission, perfusion and ventilation procedures

    Although there is controversy over the value of radionuclide lung scans in the diagnosis of pulmonary thrombo-embolism, the procedure remains non-invasive, accurate and precise given proper methodological and interpretive criteria. Reviewing 959 procedures from the past decade in 539 patients, including 23 autopsies (correctly diagnosed antemortem), 93 emergencies (67 in 1973; 26 since), 8 pulmonary angiograms, 649 (8 view) perfusion studies with transmission view and 'first pass' flow using 99mTc-Macroparticles (MAA or HAM), 257 ventilation studies using 133-Xenen, 53 'aerosol' studies (either 'wet' or 'dry' radioinhalant), 113 computer analyses and 13 'closing volumes' (as well estimated by imaging as standard techniques (p<0.05)); a sensitivity of 92 percent, a specificity of 96 percent, an efficiency of 96 percent with a probability of disease with a positive study of 90 percent and a likelihood of disease with a negative study of 2 percent were found. Peripheral thrombosis and positive lung scans for pulmonary embolism occurred frequently. Based on these data, the lung scan properly carried out is reliable especially to exclude pulmonary embolism, frequently rendering invasive procedures unnecessary. (Author)

  6. Quantitative atom column position analysis at the incommensurate interfaces of a (PbS)1.14NbS2 misfit layered compound with aberration-corrected HRTEM

    Aberration-corrected HRTEM is applied to explore the potential of NCSI contrast imaging to quantitatively analyse the complex atomic structure of misfit layered compounds and their incommensurate interfaces. Using the (PbS)1.14NbS2 misfit layered compound as a model system it is shown that atom column position analyses at the incommensurate interfaces can be performed with precisions reaching a statistical accuracy of ±6 pm. The procedure adopted for these studies compares experimental images taken from compound regions free of defects and interface modulations with a structure model derived from XRD experiments and with multi-slice image simulations for the corresponding NCSI contrast conditions used. The high precision achievable in such experiments is confirmed by a detailed quantitative analysis of the atom column positions at the incommensurate interfaces, proving a tetragonal distortion of the monochalcogenide sublattice. -- Research Highlights: → Quantitative aberration-corrected HRTEM analysis of atomic column positions in (PbS)1.14NbS2 misfit layered compound reveals tetragonal distortion of the PbS subsystem. → Detailed comparison of multi-slice simulations with the experimental NCSI contrast condition imaging results lead to a high precision (better than 10 pm) for determining the positions of atoms. → Precision in gaining information of local structure at atomic scale is demonstrated, which may not be accessible by means of X-ray and neutron diffraction analysis.

  7. High resolution scanning transmission electron microscopy (HR STEM) analysis of re-deposited layer on ASDEX Upgrade tile

    Rasinski, M., E-mail: mrasin@o2.pl [Warsaw University of Technology, Faculty of Material Science and Engineering, Woloska 141, 02-507 Warsaw (Poland); Fortuna-Zalesna, E. [Warsaw University of Technology, Faculty of Material Science and Engineering, Woloska 141, 02-507 Warsaw (Poland); Mayer, M.; Neu, R. [Max-Planck-Institut fuer Plasmaphysik, Euratom Association, Boltzmannstrasse 2, D-85748 Garching (Germany); Plocinski, T.; Lewandowska, M.; Kurzydlowski, K.J. [Warsaw University of Technology, Faculty of Material Science and Engineering, Woloska 141, 02-507 Warsaw (Poland)

    2011-10-15

    Erosion and re-deposition of plasma-facing components (PFCs) is one of the most important issues in fusion devices and as such it is an area of interest for many research groups. However, the structure and composition of re-deposited layers as well as the mechanism and condition of their formation are not yet fully described and understood. In the present study, the structure and the composition of co-deposited layers, which developed at the outer divertor strike point tiles in ASDEX Upgrade during the 2009 campaign were examined. High resolution scanning transmission electron microscopy (HRSTEM) combined with energy-dispersive X-ray spectroscopy (EDS) and electron energy loss spectroscopy (EELS) have been used to identify deposits composition and morphology. Tungsten foam like structure and co-deposits rich in tungsten, oxygen, carbon, boron and nitrogen were observed.

  8. High resolution scanning transmission electron microscopy (HR STEM) analysis of re-deposited layer on ASDEX Upgrade tile

    Erosion and re-deposition of plasma-facing components (PFCs) is one of the most important issues in fusion devices and as such it is an area of interest for many research groups. However, the structure and composition of re-deposited layers as well as the mechanism and condition of their formation are not yet fully described and understood. In the present study, the structure and the composition of co-deposited layers, which developed at the outer divertor strike point tiles in ASDEX Upgrade during the 2009 campaign were examined. High resolution scanning transmission electron microscopy (HRSTEM) combined with energy-dispersive X-ray spectroscopy (EDS) and electron energy loss spectroscopy (EELS) have been used to identify deposits composition and morphology. Tungsten foam like structure and co-deposits rich in tungsten, oxygen, carbon, boron and nitrogen were observed.

  9. Morphology of gills of the seawater fish Cathorops spixii (Agassiz (Ariidae by scanning and transmission electron microscopy

    Daura R. Eiras-Stofella

    2002-12-01

    Full Text Available Gills of the seawater fish Cathorops spixii (Agassiz, 1829 were submitted to routine processing for observation in scanning and transmission electron microscopy. The wrinkled surface of the gill filaments showed well-defined cellular ultrastructures. Microridges on cellular surface were projected over all gill structures, including respiratory lamellae. Chloride cells were usually at primary lamellae. Some rodlet cells were found. Mucous secretory cells were uncommon at all parts of the gill arches. The pharyngeal region of the gill arches showed a lot of taste buds but no spines. There were small and strong rakers. Such morphology is indicative of fishes that swallow small food but do not have filtering habits. At the ultrastructural level the gills of C. spixii presented the typical morphological pattern of Teleostei fishes.

  10. Whole-cell imaging of the budding yeast Saccharomyces cerevisiae by high-voltage scanning transmission electron tomography

    Electron tomography using a high-voltage electron microscope (HVEM) provides three-dimensional information about cellular components in sections thicker than 1 μm, although in bright-field mode image degradation caused by multiple inelastic scattering of transmitted electrons limit the attainable resolution. Scanning transmission electron microscopy (STEM) is believed to give enhanced contrast and resolution compared to conventional transmission electron microscopy (CTEM). Samples up to 1 μm in thickness have been analyzed with an intermediate-voltage electron microscope because inelastic scattering is not a critical limitation, and probe broadening can be minimized. Here, we employed STEM at 1 MeV high-voltage to extend the useful specimen thickness for electron tomography, which we demonstrate by a seamless tomographic reconstruction of a whole, budding Saccharomyces cerevisiae yeast cell, which is ∼3 μm in thickness. High-voltage STEM tomography, especially in the bright-field mode, demonstrated sufficiently enhanced contrast and intensity, compared to CTEM tomography, to permit segmentation of major organelles in the whole cell. STEM imaging also reduced specimen shrinkage during tilt-series acquisition. The fidelity of structural preservation was limited by cytoplasmic extraction, and the spatial resolution was limited by the relatively large convergence angle of the scanning probe. However, the new technique has potential to solve longstanding problems of image blurring in biological specimens beyond 1 μm in thickness, and may facilitate new research in cellular structural biology. - Highlights: • High voltage TEM and STEM tomography were compared to visualize whole yeast cells. • 1-MeV STEM-BF tomography had significant improvements in image contrast and SNR. • 1-MeV STEM tomography showed less specimen shrinkage than the TEM tomography. • KMnO4 post-treatment permitted segmenting the major cellular components

  11. Whole-cell imaging of the budding yeast Saccharomyces cerevisiae by high-voltage scanning transmission electron tomography

    Murata, Kazuyoshi, E-mail: kazum@nips.ac.jp [National Institute for Physiological Sciences, Okazaki, Aichi 444-8585 (Japan); Esaki, Masatoshi; Ogura, Teru [Institute of Molecular Embryology and Genetics, Kumamoto University, Kumamoto 860-0811 (Japan); Arai, Shigeo; Yamamoto, Yuta; Tanaka, Nobuo [Ecotopia Science Institute, Nagoya University, Nagoya, Aichi 464-8603 (Japan)

    2014-11-15

    Electron tomography using a high-voltage electron microscope (HVEM) provides three-dimensional information about cellular components in sections thicker than 1 μm, although in bright-field mode image degradation caused by multiple inelastic scattering of transmitted electrons limit the attainable resolution. Scanning transmission electron microscopy (STEM) is believed to give enhanced contrast and resolution compared to conventional transmission electron microscopy (CTEM). Samples up to 1 μm in thickness have been analyzed with an intermediate-voltage electron microscope because inelastic scattering is not a critical limitation, and probe broadening can be minimized. Here, we employed STEM at 1 MeV high-voltage to extend the useful specimen thickness for electron tomography, which we demonstrate by a seamless tomographic reconstruction of a whole, budding Saccharomyces cerevisiae yeast cell, which is ∼3 μm in thickness. High-voltage STEM tomography, especially in the bright-field mode, demonstrated sufficiently enhanced contrast and intensity, compared to CTEM tomography, to permit segmentation of major organelles in the whole cell. STEM imaging also reduced specimen shrinkage during tilt-series acquisition. The fidelity of structural preservation was limited by cytoplasmic extraction, and the spatial resolution was limited by the relatively large convergence angle of the scanning probe. However, the new technique has potential to solve longstanding problems of image blurring in biological specimens beyond 1 μm in thickness, and may facilitate new research in cellular structural biology. - Highlights: • High voltage TEM and STEM tomography were compared to visualize whole yeast cells. • 1-MeV STEM-BF tomography had significant improvements in image contrast and SNR. • 1-MeV STEM tomography showed less specimen shrinkage than the TEM tomography. • KMnO{sub 4} post-treatment permitted segmenting the major cellular components.

  12. Impulse radio ultra wideband wireless transmission of dopamine concentration levels recorded by fast-scan cyclic voltammetry.

    Ebrazeh, Ali; Bozorgzadeh, Bardia; Mohseni, Pedram

    2015-08-01

    This paper demonstrates the feasibility of utilizing impulse radio ultra wideband (IR-UWB) signaling technique for reliable, wireless transmission of dopamine concentration levels recorded by fast-scan cyclic voltammetry (FSCV) at a carbon-fiber microelectrode (CFM) to address the problem of elevated data rates in high-channel-count neurochemical monitoring. Utilizing an FSCV-sensing chip fabricated in AMS 0.35μm 2P/4M CMOS, a 3-5-GHz, IR-UWB transceiver (TRX) chip fabricated in TSMC 90nm 1P/9M RF CMOS, and two off-chip, miniature, UWB antennae, wireless transfer of pseudo-random binary sequence (PRBS) data at 50Mbps over a distance of wireless transmission of dopamine concentration levels prerecorded with FSCV at a CFM during flow injection analysis (FIA) is also demonstrated with transmitter (TX) power dissipation of only ~4.4μW from 1.2V, representing two orders of magnitude reduction in TX power consumption compared to that of a conventional frequency-shift-keyed (FSK) link operating at ~433MHz. PMID:26737929

  13. Atomically resolved FeSe/SrTiO3(001) interface structure by scanning transmission electron microscopy

    Li, Fangsen; Zhang, Qinghua; Tang, Chenjia; Liu, Chong; Shi, Jinan; Nie, CaiNa; Zhou, Guanyu; Li, Zheng; Zhang, Wenhao; Song, Can-Li; He, Ke; Ji, Shuaihua; Zhang, Shengbai; Gu, Lin; Wang, Lili; Ma, Xu-Cun; Xue, Qi-Kun

    2016-06-01

    Interface-enhanced high-temperature superconductivity in one unit-cell FeSe films on SrTiO3(001) (STO) substrate has recently attracted much attention in condensed matter physics and material science. By combined in situ scanning tunneling microscopy/spectroscopy and ex situ scanning transmission electron microscopy studies, we report on atomically resolved structure including both lattice constants and actual atomic positions of the FeSe/STO interface under both non-superconducting and superconducting states. We observed TiO2 double layers and significant atomic displacements in the top two layers of STO, lattice compression of the Se-Fe-Se triple layer, and relative shift between bottom Se and topmost Ti atoms. By imaging the interface structures under various superconducting states, we unveil a close correlation between interface structure and superconductivity. Our atomic-scale identification of FeSe/STO interface structure provides insight on investigating the pairing mechanism of this interface-enhanced high-temperature superconducting system.

  14. EPS composition and calcification potential of tufa-dominating cyanobacteria investigated by Scanning Transmission X-ray Microscopy (STXM) and Laser Scanning Microscopy (LSM)

    Zippel, Barbara; Dynes, James J.; Obst, Martin; Lawrence, John R.; Neu, Thomas R.

    2010-05-01

    Tufa deposits in freshwater habitats are the result of calcium carbonate precipitation within interfacial microbial ecosystems. Calcite precipitation is influenced by the saturation index and the occurrence of extracellular polymeric substances (EPS) which are produced by a variety of microorganisms. In theory, the first important step of biologically induced calcification processes is the adsorption of calcium ions by extracellular polymeric substances (EPS) produced by cyanobacteria. In the present study we take advantage of Laser Scanning Microscopy (LSM) and combine it with Synchrotron imaging using Scanning Transmission X-ray Microscopy (STXM). STXM represents a technique that allows simultaneous analysis of inorganic and organic constituents as a scale of 50 nm. By means of STXM it is possible to differentiate between calcium carbonate phases at the Ca L-edge. Furthermore, STXM has also been used at the C K-edge to map the major biomolecules (proteins, lipids, and polysaccharides). The purpose of this study is to find out if there are differences in calcium adsorption depending on specific composition of the EPS produced by filamentous cyanobacteria isolated from a German hard water creek (Westerhöfer Bach, Harz Mountains). The goal was to elucidate the potential of biofilms constituents, including microbial cell surfaces as well as extracellular polymeric substances, in triggering the formation of calcium carbonate in tufa systems. For this purpose three filamentous cyanobacteria (Pseudanabaena sp., Leptolyngbya sp. and Nostoc sp.) were cultivated in creek-adapted as well as standard media (BG11) on polycarbonate slides. In situ EPS composition was detected by means of fluorescence lectin-binding approach (FLBA) using 23 commercially available lectins with different specificities for mono- and disaccharides and amino sugars. For CaCO3 nucleation experiments cyanobacterial biofilms grown on polycarbonate slides were deposited in NaHCO3/CaCl2 solutions

  15. Classification of Multiple Types of Organic Carbon Composition in Atmospheric Particles by Scanning Transmission X-Ray Microscopy Analysis

    Kilcoyne, Arthur L; Takahama, S.; Gilardoni, S.; Russell, L.M.; Kilcoyne, A.L.D.

    2007-05-16

    A scanning transmission X-ray microscope at the Lawrence Berkeley National Laboratory is used to measure organic functional group abundance and morphology of atmospheric aerosols. We present a summary of spectra, sizes, and shapes observed in 595 particles that were collected and analyzed between 2000 and 2006. These particles ranged between 0.1 and 12 mm and represent aerosols found in a large range of geographical areas, altitudes, and times. They include samples from seven different field campaigns: PELTI, ACE-ASIA, DYCOMS II, Princeton, MILAGRO (urban), MILAGRO (C-130), and INTEX-B. At least 14 different classes of organic particles show different types of spectroscopic signatures. Different particle types are found within the same region while the same particle types are also found in different geographical domains. Particles chemically resembling black carbon, humic-like aerosols, pine ultisol, and secondary or processed aerosol have been identified from functional group abundance and comparison of spectra with those published in the literature.

  16. Dose limited reliability of quantitative annular dark field scanning transmission electron microscopy for nano-particle atom-counting

    Quantitative annular dark field scanning transmission electron microscopy (ADF STEM) has become a powerful technique to characterise nano-particles on an atomic scale. Because of their limited size and beam sensitivity, the atomic structure of such particles may become extremely challenging to determine. Therefore keeping the incoming electron dose to a minimum is important. However, this may reduce the reliability of quantitative ADF STEM which will here be demonstrated for nano-particle atom-counting. Based on experimental ADF STEM images of a real industrial catalyst, we discuss the limits for counting the number of atoms in a projected atomic column with single atom sensitivity. We diagnose these limits by combining a thorough statistical method and detailed image simulations. - Highlights: • Limited size and beam sensitivity of nano-particles challenge their quantification. • Keeping the electron dose to a minimum is therefore important. • Reliability of quantitative ADF STEM for atom-counting is demonstrated. • Limits for single atom sensitivity are discussed. • Limits are diagnosed by combining simulations and a statistical method

  17. Scanning transmission electron microscopic study of molluscan hemocyanins in various aggregation states: comparison with light scattering molecular weights.

    Hamilton, M G; Herskovits, T T; Furcinitti, P S; Wall, J S

    1989-12-01

    The masses of individual particles of the hemocyanins of six members of two molluscan classes, Polyplacophora and Gastropoda, have been determined by scanning transmission electron microscopy (STEM) of unstained specimens dried from the frozen state. The decameric hemocyanins of two chitons, Mopalia muscosa and Stenoplax conspicua, had masses of 4.20 +/- 0.18 and 4.47 +/- 0.56 MDa, respectively; the didecameric hemocyanins of two gastropods, Fasciolaria tulipa and Pleuroploca gigantea, had masses of 8.67 +/- 0.44 and 8.96 +/- 0.39 MDa, respectively; and the tridecameric hemocyanin of Lunatia heros had a mass of 13.50 +/- 0.44 MDa. The STEM values were in close agreement with those obtained by light scattering measurements of the same samples in solution. For Busycon contrarium, a gastropod with a multidecameric hemocyanin, nine size classes from didecamers to decadecamers with masses that corresponded to multiples of a basic decamer (4.4 MDa) were detected. The appearance of unstained specimens of the cylindrical particles differs from negatively stained specimens. Viewed end-on the cylinders show no internal structure, but in well-preserved specimens cavities are apparent in the side views of the cylinders that resemble those seen in negatively stained specimens. Although they lack the characteristic "tiered" appearance, the number of decameric units can be counted and their arrangement within the particle seen. PMID:2634708

  18. Design and Performance of a TES X-ray Microcalorimeter Array for Energy Dispersive Spectroscopy on Scanning Transmission Electron Microscope

    Muramatsu, Haruka; Nagayoshi, K.; Hayashi, T.; Sakai, K.; Yamamoto, R.; Mitsuda, K.; Yamasaki, N. Y.; Maehata, K.; Hara, T.

    2016-07-01

    We discuss the design and performance of a transition edge sensor (TES) X-ray microcalorimeter array for scanning transmission electron microscope (STEM)-energy dispersive X-ray spectroscopy (EDS). The TES X-ray microcalorimeter has better energy resolution compared to conventional silicon drift detector and STEM-EDS utilizing a TES detector makes it possible to map the distribution of elements on a specimen in addition to analyze the composition. The requirement for a TES detector is a high counting rate (>20 kcps), wide energy band (0.5-15 keV) and good energy resolution (<10 eV) full width at half maximum. The major improvement of this development is to increase the maximum counting rate. In order to accommodate the high counting rate, we adopted an 8 × 8 format, 64-pixel array and common biasing scheme for the readout method. We did all design and fabrication of the device in house. With the device we have fabricated most recently, the pulse decay time is 40 \\upmu s which is expected to achieve 50 kcps. For a single pixel, the measured energy resolution was 7.8 eV at 5.9 keV. This device satisfies the requirements of counting rate and energy resolution, although several issues remain where the performance must be confirmed.

  19. Imaging and elemental mapping of biological specimens with a dual-EDS dedicated scanning transmission electron microscope

    Wu, J.S., E-mail: jinsong-wu@northwestern.edu [Northwestern University Atomic and Nanoscale Characterization Experimental (NUANCE) Center, Northwestern University, Evanston, IL 60208 (United States); Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208 (United States); Kim, A.M. [Department of Obstetrics and Gynecology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611 (United States); Chemistry of Life Processes Institute, Northwestern University, Evanston, IL 60208 (United States); Bleher, R. [Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208 (United States); Chemistry of Life Processes Institute, Northwestern University, Evanston, IL 60208 (United States); Myers, B.D. [Northwestern University Atomic and Nanoscale Characterization Experimental (NUANCE) Center, Northwestern University, Evanston, IL 60208 (United States); Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208 (United States); Marvin, R.G. [Department of Chemistry, Northwestern University, Evanston, IL 60208 (United States); Chemistry of Life Processes Institute, Northwestern University, Evanston, IL 60208 (United States); Inada, H.; Nakamura, K. [Hitachi High-Technologies Corporation, Ibaraki 312-8504 (Japan); Zhang, X.F. [Hitachi High Technologies America, Inc., 5960 Inglewood Drive, Pleasanton, California 94588 (United States); Roth, E. [Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208 (United States); Chemistry of Life Processes Institute, Northwestern University, Evanston, IL 60208 (United States); Li, S.Y. [Northwestern University Atomic and Nanoscale Characterization Experimental (NUANCE) Center, Northwestern University, Evanston, IL 60208 (United States); and others

    2013-05-15

    A dedicated analytical scanning transmission electron microscope (STEM) with dual energy dispersive spectroscopy (EDS) detectors has been designed for complementary high performance imaging as well as high sensitivity elemental analysis and mapping of biological structures. The performance of this new design, based on a Hitachi HD-2300A model, was evaluated using a variety of biological specimens. With three imaging detectors, both the surface and internal structure of cells can be examined simultaneously. The whole-cell elemental mapping, especially of heavier metal species that have low cross-section for electron energy loss spectroscopy (EELS), can be faithfully obtained. Optimization of STEM imaging conditions is applied to thick sections as well as thin sections of biological cells under low-dose conditions at room and cryogenic temperatures. Such multimodal capabilities applied to soft/biological structures usher a new era for analytical studies in biological systems. - Highlights: ► Applications of STEM in characterization of biological samples are demonstrated. ► Elemental analyses are performed by dual EDS and EELS. ► Both the surface and internal structure of cells can be studied simultaneously. ► The imaging contrast in low-dose cryo-STEM has been analyzed.

  20. Imaging and elemental mapping of biological specimens with a dual-EDS dedicated scanning transmission electron microscope

    A dedicated analytical scanning transmission electron microscope (STEM) with dual energy dispersive spectroscopy (EDS) detectors has been designed for complementary high performance imaging as well as high sensitivity elemental analysis and mapping of biological structures. The performance of this new design, based on a Hitachi HD-2300A model, was evaluated using a variety of biological specimens. With three imaging detectors, both the surface and internal structure of cells can be examined simultaneously. The whole-cell elemental mapping, especially of heavier metal species that have low cross-section for electron energy loss spectroscopy (EELS), can be faithfully obtained. Optimization of STEM imaging conditions is applied to thick sections as well as thin sections of biological cells under low-dose conditions at room and cryogenic temperatures. Such multimodal capabilities applied to soft/biological structures usher a new era for analytical studies in biological systems. - Highlights: ► Applications of STEM in characterization of biological samples are demonstrated. ► Elemental analyses are performed by dual EDS and EELS. ► Both the surface and internal structure of cells can be studied simultaneously. ► The imaging contrast in low-dose cryo-STEM has been analyzed

  1. Dose limited reliability of quantitative annular dark field scanning transmission electron microscopy for nano-particle atom-counting

    De Backer, A.; Martinez, G.T. [Electron Microscopy for Materials Science (EMAT), University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); MacArthur, K.E.; Jones, L. [Department of Materials, University of Oxford, 16 Parks Road, Oxford OX1 3PH (United Kingdom); Béché, A. [Electron Microscopy for Materials Science (EMAT), University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Nellist, P.D. [Department of Materials, University of Oxford, 16 Parks Road, Oxford OX1 3PH (United Kingdom); Van Aert, S., E-mail: sandra.vanaert@uantwerpen.be [Electron Microscopy for Materials Science (EMAT), University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium)

    2015-04-15

    Quantitative annular dark field scanning transmission electron microscopy (ADF STEM) has become a powerful technique to characterise nano-particles on an atomic scale. Because of their limited size and beam sensitivity, the atomic structure of such particles may become extremely challenging to determine. Therefore keeping the incoming electron dose to a minimum is important. However, this may reduce the reliability of quantitative ADF STEM which will here be demonstrated for nano-particle atom-counting. Based on experimental ADF STEM images of a real industrial catalyst, we discuss the limits for counting the number of atoms in a projected atomic column with single atom sensitivity. We diagnose these limits by combining a thorough statistical method and detailed image simulations. - Highlights: • Limited size and beam sensitivity of nano-particles challenge their quantification. • Keeping the electron dose to a minimum is therefore important. • Reliability of quantitative ADF STEM for atom-counting is demonstrated. • Limits for single atom sensitivity are discussed. • Limits are diagnosed by combining simulations and a statistical method.

  2. Design and Performance of a TES X-ray Microcalorimeter Array for Energy Dispersive Spectroscopy on Scanning Transmission Electron Microscope

    Muramatsu, Haruka; Nagayoshi, K.; Hayashi, T.; Sakai, K.; Yamamoto, R.; Mitsuda, K.; Yamasaki, N. Y.; Maehata, K.; Hara, T.

    2016-02-01

    We discuss the design and performance of a transition edge sensor (TES) X-ray microcalorimeter array for scanning transmission electron microscope (STEM)-energy dispersive X-ray spectroscopy (EDS). The TES X-ray microcalorimeter has better energy resolution compared to conventional silicon drift detector and STEM-EDS utilizing a TES detector makes it possible to map the distribution of elements on a specimen in addition to analyze the composition. The requirement for a TES detector is a high counting rate (> 20 kcps), wide energy band (0.5-15 keV) and good energy resolution (< 10 eV) full width at half maximum. The major improvement of this development is to increase the maximum counting rate. In order to accommodate the high counting rate, we adopted an 8 × 8 format, 64-pixel array and common biasing scheme for the readout method. We did all design and fabrication of the device in house. With the device we have fabricated most recently, the pulse decay time is 40 \\upmu s which is expected to achieve 50 kcps. For a single pixel, the measured energy resolution was 7.8 eV at 5.9 keV. This device satisfies the requirements of counting rate and energy resolution, although several issues remain where the performance must be confirmed.

  3. A Transition Edge Sensor Microcalorimeter System for the Energy Dispersive Spectroscopy Performed on a Scanning-Transmission Electron Microscope

    Maehata, K.; Hara, T.; Mitsuda, K.; Hidaka, M.; Tanaka, K.; Yamanaka, Y.

    2015-11-01

    We are conducting the development of a transition edge sensor (TES) microcalorimeter system for energy-dispersive X-ray spectroscopy (EDS), performed using a scanning-transmission electron microscope (STEM). The operating temperature of the TES microcalorimeter was maintained using a compact dry 3 He-4 He dilution refrigerator. This was pre-cooled by a remote helium cooling loop system and a Gifford-McMahon cooler. These conditions allowed for high-resolution STEM imaging to be achieved. A single-pixel TES microcalorimeter with a polycapillary optic was selected to demonstrate the analytical operation of the EDS system in the STEM. For a Ti-It-Pt sample, an X-ray energy resolution of 8.6 eV full-width at half maximum (FWHM) was obtained at Ir M_{α 1} , Pt M_{α 1} , and Ir M_{β } . Using an electron device sample, element distribution maps of Si, Ti, and W were obtained using a Si K_{α 1} X-ray energy resolution of 9.7 eV FWHM.

  4. Structural characterization of annatto seeds (Bixa orellana) by transmission and scanning electron microscopy submitted to gamma radiation for dormancy break

    The annatto (Bixa orellana) is the only species of the Bixaceae family. From the seeds an important food colorant is obtained, bixin, for the industry and domestic use. More recently studies have focused more extensively in medicinal purpose of the species. Due to structural and physiologic characteristics, the seeds have low germination rate, around 30 %. The irradiation of seeds with gamma radiation can promote the increase and/or acceleration of germination, better plant development and productivity, among other aspects. The radiation doses used for this purpose should not cause genetic modifications in the organism, hence experimentation is needed to define the appropriate doses. Absence of research done annatto related to the use of the irradiation aiming at the increase of germination rates lead to the structural characterization of the annatto seeds submitted to gamma radiation through transmission (TEM) and scanning electron microscopy (SEM). The objective of this study was to verify the effect of radiation on the seeds structures during the process of dormancy break. Dry seeds and seeds immersed in distilled water for 24 hours were submitted to gamma radiation from source of Co60 type Gammacell-220 at CENA/USP, at doses 100 Gy. After irradiation the seeds were processed for TEM and SEM. Preliminary results, showed structural modifications in the seeds. (author)

  5. Unraveling the redox behavior of a CoMoS hydrodesulfurization catalyst : A scanning transmission X-ray microscopy study in the tender X-ray range

    Al Samarai, Mustafa; Meirer, Florian; Karunakaran, Chithra; Wang, Jian; Vogt, Eelco T C; Zandbergen, Henny W.; Weber, Thomas; Weckhuysen, Bert M.; De Groot, Frank M F

    2015-01-01

    We visualize the elemental zoning in an alumina-supported cobalt molybdenum sulfide (CoMoS) catalyst with scanning transmission X-ray microscopy (STXM). We use the Canadian Light Source beamline 10-ID's (SM) unique combination of soft X-ray and tender X-ray STXM to determine the spatial variation of

  6. EVALUATION OF THE ULTRASTRUCTURE OF THE SMALL INTESTINE OF HIV INFECTED CHILDREN BY TRANSMISSION AND SCANNING ELECTRONIC MICROSCOPY

    Christiane Araujo Chaves LEITE

    2013-03-01

    Full Text Available Objectives To describe HIV children's small intestinal ultrastructural findings. Methods Descriptive, observational study of small intestine biopsies performed between August 1994 and May 1995 at São Paulo, SP, Brazil. This material pertained to 11 HIV infected children and was stored in a laboratory in paraffin blocks. Scanning and transmission electronic microscopy were used to view those intestine samples and ultrastructural findings were described by analyzing digitalized photos of this material. Ethical Committee approval was obtained. Results In most samples scanning microscopy showed various degrees of shortening and decreasing number of microvilli and also completes effacements in some areas. Derangement of the enterocytes was seen frequently and sometimes cells well defined borders limits seemed to be loosened. In some areas a mucous-fibrin like membrane with variable thickness and extension appeared to partially or totally coat the epithelial surface. Fat drops were present in the intestinal lumen in various samples and a bacterium morphologically resembling bacilli was seen in two occasions. Scanning microscopy confirmed transmission microscopy microvilli findings and also showed little “tufts” of those structures. In addition, it showed an increased number of vacuoles and multivesicular bodies inside various enterocytes, an increased presence of intraepithelial lymphocytes, mitochondrial vacuolization and basement membrane enlargement in the majority of samples analyzed. However, some samples exhibited normal aspect. Conclusions Our study showed the common occurrence of various important intestinal ultrastructural alterations with variable degrees among HIV infected children, some of them in our knowledge not described before. Objetivos Descrever achados ultra-estruturais do intestino delgado de crianças infectadas pelo HIV. Métodos Estudo descritivo, observacional de biopsias do intestino delgado, realizada entre agosto de

  7. Characterization and classification of psittacine atherosclerotic lesions by histopathology, digital image analysis, transmission and scanning electron microscopy.

    Beaufrère, Hugues; Nevarez, Javier G; Holder, Kali; Pariaut, Romain; Tully, Thomas N; Wakamatsu, Nobuko

    2011-10-01

    Atherosclerosis is a degenerative and inflammatory vascular disease characterized in mammals and birds by the accumulation of inflammatory cells, lipids, calcium, and formation of large fibrofatty lesions within the intima of arteries resulting in the disorganization of the arterial wall and stenosis of the lumen. Despite the high incidence of atherosclerosis in parrots and the high number of case reports, there are few pathologic investigations and the ultrastructural study of the lesions has not been documented. Sixty-three major arteries were collected from 24 psittacine birds of 11 species during routine post-mortem examinations. Samples from the major arteries were fixed in 2% paraformaldehyde and 1.25% glutaraldehyde, and processed for transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Additional samples were fixed in 10% formalin and embedded in paraffin for histological examination. Additional histochemical stains for calcium, elastic fibres, and lipid were performed. Toluidine blue-stained 0.5 µm-thick resin sections were also obtained. Digital image analysis was performed to provide objective quantitative information on the different lesions. The histopathology and ultrastructure of psittacine atherosclerosis were found to be similar to other avian and mammalian species. Seven lesion types could be described, which were similar to the human classification system. Digital image analysis, TEM, and SEM helped to further describe the lesions and refine the classification system. TEM findings were similar to other avian and mammalian species with the notable presence of macrophage-derived and smooth muscle cell-derived foam cells and extracellular lipid. SEM revealed various stages of endothelial surface defects and, occasionally, adherent blood cells. PMID:21879992

  8. Development of a parallel detection and processing system using a multidetector array for wave field restoration in scanning transmission electron microscopy.

    Taya, Masaki; Matsutani, Takaomi; Ikuta, Takashi; Saito, Hidekazu; Ogai, Keiko; Harada, Yoshihito; Tanaka, Takeo; Takai, Yoshizo

    2007-08-01

    A parallel image detection and image processing system for scanning transmission electron microscopy was developed using a multidetector array consisting of a multianode photomultiplier tube arranged in an 8 x 8 square array. The system enables the taking of 64 images simultaneously from different scattered directions with a scanning time of 2.6 s. Using the 64 images, phase and amplitude contrast images of gold particles on an amorphous carbon thin film could be separately reconstructed by applying respective 8 shaped bandpass Fourier filters for each image and multiplying the phase and amplitude reconstructing factors. PMID:17764327

  9. Scanning electron microscopic, transmission electron microscopic, and confocal laser scanning microscopic observation of fibroblasts cultured on microgrooved surfaces of bulk titanium substrata

    Braber, den E.T.; Jansen, H.V.; Boer, de M.J.; Croes, H.J.E.; Elwenspoek, M.; Ginsel, L.A.; Jansen, J.A.

    1998-01-01

    During this study, microtechnology and plasma etching were used to produce gratings 1.0 (TiD01), 2.0 (TiD02), 5.0 (TiD05), and 10.0 µm wide (TiD10) into commercially pure titanium wafers. After incubation of rat dermal fibroblast (RDFs) on these surfaces for 3 days, the cells were observed with scan

  10. Composition analysis of a polymer electrolyte membrane fuel cell microporous layer using scanning transmission X-ray microscopy and near edge X-ray absorption fine structure analysis

    George, Michael G.; Wang, Jian; Banerjee, Rupak; Bazylak, Aimy

    2016-03-01

    The novel application of scanning transmission X-ray microscopy (STXM) to the microporous layer (MPL) of a polymer electrolyte membrane fuel cell is investigated. A spatially resolved chemical component distribution map is obtained for the MPL of a commercially available SGL 25 BC sample. This is achieved with near edge X-ray absorption fine structure spectroscopic analysis. Prior to analysis the sample is embedded in non-reactive epoxy and ultra-microtomed to a thickness of 100 nm. Polytetrafluoroethylene (PTFE), carbon particle agglomerates, and supporting epoxy resin distributions are identified and reconstructed for a scanning area of 6 μm × 6 μm. It is observed that the spatial distribution of PTFE is strongly correlated to the carbon particle agglomerations. Additionally, agglomerate structures of PTFE are identified, possibly indicating the presence of a unique mesostructure in the MPL. STXM analysis is presented as a useful technique for the investigation of chemical species distributions in the MPL.

  11. Correlative Fluorescence Microscopy and Scanning Transmission Electron Microscopy of Quantum Dot Labeled Proteins in Whole Cells in Liquid

    Dukes, Madeline J.; Peckys, Diana B.; de Jonge, Niels

    2010-01-01

    Correlative fluorescence microscopy and transmission electron microscopy (TEM) is a state-of-the-art microscopy methodology to study cellular function, combining the functionality of light microscopy with the high resolution of electron microscopy. However, this technique involves complex sample preparation procedures due to its need for either thin sections or frozen samples for TEM imaging. Here, we introduce a novel correlative approach capable of imaging whole eukaryotic cells in liquid w...

  12. Submicron mass spectrometry imaging of single cells by combined use of mega electron volt time-of-flight secondary ion mass spectrometry and scanning transmission ion microscopy

    In order to better understand biochemical processes inside an individual cell, it is important to measure the molecular composition at the submicron level. One of the promising mass spectrometry imaging techniques that may be used to accomplish this is Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS), using MeV energy heavy ions for excitation. MeV ions have the ability to desorb large intact molecules with a yield that is several orders of magnitude higher than conventional SIMS using keV ions. In order to increase the spatial resolution of the MeV TOF-SIMS system, we propose an independent TOF trigger using a STIM (scanning transmission ion microscopy) detector that is placed just behind the thin transmission target. This arrangement is suitable for biological samples in which the STIM detector simultaneously measures the mass distribution in scanned samples. The capability of the MeV TOF-SIMS setup was demonstrated by imaging the chemical composition of CaCo-2 cells

  13. Submicron mass spectrometry imaging of single cells by combined use of mega electron volt time-of-flight secondary ion mass spectrometry and scanning transmission ion microscopy

    Siketić, Zdravko; Bogdanović Radović, Ivančica; Jakšić, Milko; Popović Hadžija, Marijana; Hadžija, Mirko [Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb (Croatia)

    2015-08-31

    In order to better understand biochemical processes inside an individual cell, it is important to measure the molecular composition at the submicron level. One of the promising mass spectrometry imaging techniques that may be used to accomplish this is Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS), using MeV energy heavy ions for excitation. MeV ions have the ability to desorb large intact molecules with a yield that is several orders of magnitude higher than conventional SIMS using keV ions. In order to increase the spatial resolution of the MeV TOF-SIMS system, we propose an independent TOF trigger using a STIM (scanning transmission ion microscopy) detector that is placed just behind the thin transmission target. This arrangement is suitable for biological samples in which the STIM detector simultaneously measures the mass distribution in scanned samples. The capability of the MeV TOF-SIMS setup was demonstrated by imaging the chemical composition of CaCo-2 cells.

  14. Histological, Scanning And Transmission Electron Microscopic Studies On The Possible Protective Role Of Ginger Extract Against AcrylamideInduced Intestinal Damage In Mice

    Hala Galal El-Tantawi

    2007-12-01

    Full Text Available Objective: This study was carried out to evaluate the protective effect of ginger Zingeber officinale extract (ZOE against the acrylamide (AC which is an industrial chemical used in water treatment and it is synthesized during cooking of starch food at high temperature. Method: Thirty adult male albino mice, each weighs 20-25 g were divided into three groups (10 mice/group: (Icontrol group. (IIacrylamide treated group. (III acrylamide & ginger group. Acrylamide was given to experimental animals in the drinking water at a non-lethal dose of 200 p.p.m for 10 weeks (3 days/week. Ginger extract was orally administrated at 50 mg/L (~5 ml/day for 10 weeks (3 days/week. The ileum samples were collected for light microscope study and for scanning and transmission electron microscope examination. Results: This study revealed that acrylamide induces pathological changes of the ileum of the treated mice specially the absorptive epithelial cells. The scanning electron microscopic study revealed damage of the ileal villi, some red blood corpuscles appeared at the site of damage. The transmission electron microscopic examination clearly demonstrated degeneration of most cell organelles as mitochondria, deterioration and degranulation of the rough endoplasmic reticulum, dilatation of Golgi apparatus. Conclusion: The administration of ginger extract decreased the histological alterations and ensuring the anti-inflammatory, and antitoxic effects of ZOE at its chosen dosage level

  15. Scanning and transmission electron microscopy of a craniopharyngioma: x-ray microanalytical study of the intratumoral mineralized deposits

    Vilches, J.; Lopez, A.; Martinez, M.C.; Gomez, J.; Barbera, J.

    This paper discusses the value of scanning electron microscopy (SEM) and x-ray microanalysis in the classification of craniopharyngiomas. This neoplasm shows epithelial nest, cords of cuboid cells, foci of squamous metaplasia, and microcystic degeneration. SEM reveals that the epithelial cysts are lined with elongated cells that possess numerous microvilli and blebs and that some cysts are lined with polyhedral cells. The microvilli are interpreted as characteristic of the fast growing craniopharyngiomas. A microanalytical study of the calcified areas reveals the presence of magnesium, phosphorus, and calcium.

  16. A clinical evaluation of the quantitative accuracy of simultaneous emission/transmission scanning in whole-body positron emission tomography

    We present a clinical evaluation of the quantitative bias which is introduced during simultaneous emission/transmission (SET) acquisition for the application of whole-body positron emission tomography (PET) with fluorine-18 2-fluoro-2-deoxy-d-glucose. The quantitative accuracy of the SET technique was assessed by means of a clinical study involving 28 patients and a realistic phantom experiment. In the clinical study, SET overestimated the activity concentration in the tumours by a factor of approximately 1.10, but in the phantom study, where the tumours were smaller, the bias was found to increase to a value of 1.39. The bias in the soft tissue regions of the patient studies varied between 1.03 and 1.36, and close agreement was observed with the corresponding phantom results. The extent of the bias increased as the local activity concentration decreased and we attribute the effect to scattered photons from the transmission source which are detected in the emission window during SET. (orig.)

  17. Hubble Space Telescope hot Jupiter Transmission Spectral Survey: detection of water in HAT-P-1b from Wide Field Camera 3 near-infrared spatial scan observations

    Wakeford, H R; Deming, D; Gibson, N P; Fortney, J J; Burrows, A S; Ballester, G; Nikolov, N; Aigrain, S; Henry, G; Knutson, H; Etangs, A Lecavelier des; Pont, F; Showman, A P; Vidal-Madjar, A; Zahnle, K

    2013-01-01

    We present Hubble Space Telescope near-infrared transmission spectroscopy of the transiting hot-Jupiter HAT-P-1b. We observed one transit with Wide Field Camera 3 using the G141 low-resolution grism to cover the wavelength range 1.087- 1.678 {\\mu}m. These time series observations were taken with the newly available spatial scan mode that increases the duty cycle by nearly a factor of two, thus improving the resulting photometric precision of the data. We measure a planet-to-star radius ratio of Rp/R*=0.11709+/-0.00038 in the white light curve with the centre of transit occurring at 2456114.345+/-0.000133 (JD). We achieve S/N levels per exposure of 1840 (0.061%) at a resolution of {\\Delta\\lambda}=19.2nm (R~70) in the 1.1173 - 1.6549{\\mu}m spectral region, providing the precision necessary to probe the transmission spectrum of the planet at close to the resolution limit of the instrument. We compute the transmission spectrum using both single target and differential photometry with similar results. The resultan...

  18. Microstructural study on degradation mechanism of layered LiNi0.6Co0.2Mn0.2O2 cathode materials by analytical transmission electron microscopy

    Kim, Na Yeon; Yim, Taeeun; Song, Jun Ho; Yu, Ji-Sang; Lee, Zonghoon

    2016-03-01

    Electrochemical performance of lithium ion batteries is associated with structural and chemical stability of electrode materials. In the case of nickel-rich layered cathode materials LiNi0.6Co0.2Mn0.2O2, cation mixing, which results from the migration of transition metal ions into vacant lithium sites, is accelerated owing to similar ionic radii between nickel and lithium. However, the inevitable lattice distortions and chemical evolution have not been investigated intensely. In this paper, we report the structural evolution localized at surface regions through electron diffraction and high resolution imaging analyses with aberration-corrected transmission electron microscopy and scanning transmission electron microscopy. Repetition of volumetric change generates cracks and voids associated with deterioration of electrochemical performance. Structural change is related with (003) intensity in electron diffraction and it can be presented by dark field transmission electron microscopy imaging at a glance. Drastic structural degradation during early cycling shows relation with rapid capacity and voltage fade. Electron energy loss spectroscopy elucidates that the structural evolution caused by the migration of Ni ions accompanies chemical modification of Mn ions and creation of hole states at the O2p level. This study provides an insight into correlating structural and chemical evolution with degradation mechanism on battery performances of LiNi0.6Co0.2Mn0.2O2 cathode materials.

  19. Minimizing artifacts resulting from respiratory and cardiac motion by optimization of the transmission scan in cardiac PET/CT

    The introduction of positron emission/computed tomography (PET/CT) systems coupled with multidetector CT arrays has greatly increased the amount of clinical information in myocardial perfusion studies. The CT acquisition serves the dual role of providing high spatial anatomical detail and attenuation correction for PET. However, the differences between the interaction of respiratory and cardiac cycles in the CT and PET acquisitions presents a challenge when using the CT to determine PET attenuation correction. Three CT attenuation correction protocols were tested for their ability to produce accurate emission images: gated, a step mode acquisition covering the diastolic heart phase; normal, a high-pitch helical CT; and slow, a low-pitch, low-temporal-resolution helical CT. The amount of cardiac tissue in the emission image that overlaid lung tissue in the transmission image was used as the measure of mismatch between acquisitions. Phantom studies simulating misalignment of the heart between the transmission and emission sequences were used to correlate the amount of mismatch with the artificial defect changes in the emission image. Consecutive patients were studied prospectively with either paired gated (diastolic phase, 120 kVp, 280 mA, 2.6 s) and slow CT (0.562:1 pitch, 120 kVp, Auto-mA, 16 s) or paired normal (0.938:1 pitch, 120 kVp, Auto-mA, 4.8 s) and slow CT protocols, prior to a Rb-82 perfusion study. To determine the amount of mismatch, the transmission and emission images were converted to binary representations of attenuating tissue and cardiac tissue and overlaid using their native registration. The number of cardiac tissue pixels from the emission image present in the CT lung field yielded the magnitude of misalignment represented in terms of volume, of where a small volume indicates better registration. Acquiring a slow CT improved registration between the transmission and emission acquisitions compared to the gated and normal CT protocols. The volume

  20. Fine structures and ion images on fresh frozen dried ultrathin sections by transmission electron and scanning ion microscopy

    Takaya, K.; Okabe, M.; Sawataishi, M.; Takashima, H.; Yoshida, T

    2003-01-15

    Ion microscopy (IM) of air-dried or freeze-dried cryostat and semi-thin cryosections has provided ion images of elements and organic substances in wide areas of the tissue. For reproducible ion images by a shorter time of exposure to the primary ion beam, fresh frozen dried ultrathin sections were prepared by freezing the tissue in propane chilled with liquid nitrogen, cryocut at 60 nm, mounted on grids and silicon wafer pieces, and freeze-dried. Rat Cowper gland and sciatic nerve, bone marrow of the rat administered of lithium carbonate, tree frog and African toad spleen and buffy coat of atopic dermatitis patients were examined. Fine structures and ion images of the corresponding areas in the same or neighboring sections were observed by transmission electron microscopy (TEM) followed by sector type and time-of-flight type IM. Cells in the buffy coat contained larger amounts of potassium and magnesium while plasma had larger amounts of sodium and calcium. However, in the tissues, lithium, sodium, magnesium, calcium and potassium were distributed in the cell and calcium showed a granular appearance. A granular cell of the tree frog spleen contained sodium and potassium over the cell and magnesium and calcium were confined to granules.

  1. Varied-space grazing incidence gratings in high resolution scanning spectrometers

    We discuss the dominant geometrical aberrations of a grazing incidence reflection grating and new techniques which can be used to reduce or eliminate them. Convergent beam geometries and the aberration correction possible with varied groove spacings are each found to improve the spectral resolution and speed of grazing incidence gratings. In combination, these two techniques can result in a high resolution (λ/Δλ > 104) monochromator or scanning spectrometer with a simple rotational motion for scanning wavelength or selecting the spectral band. 21 refs., 4 figs

  2. Evaluation of Al3Mg2 precipitates and Mn-rich phase in aluminum-magnesium alloy based on scanning transmission electron microscopy imaging

    Zhu, Yakun [ORNL; Cullen, David A [ORNL; Kar, Soumya [ORNL; Free, Michael P [ORNL; Allard Jr, Lawrence Frederick [ORNL

    2012-01-01

    Scanning transmission electron microscopy (STEM) and energy dispersive X-ray spectroscopy (EDS) were used to observe intergranular and intragranular -phase (Al3Mg2) formation and growth in as-received sample and long-term (~ 1 year) thermally treated samples of 5083-H131 alloy. Rod-shaped and equiaxed particles rich in Mn, Fe, and Cr were present in the as-received and heat treated samples. The -phase precipitated along grain boundaries as well as around and between preexisting Mn-Fe-Cr rich particles. The measured thickness of -phase along grain boundaries was lower than Zener Hillert diffusion model predicted value and the potential reasons were theoretically analyzed. Dislocation networks, grain boundaries, and different preexisting particles were observed to contribute to Mg diffusion and -phase precipitation.

  3. Scanning and transmission electron microscopy of the tegument of Paranaella luquei Kohn, Baptista-Farias & Cohen, 2000 (Microcotylidae, Monogenea, parasite of a Brazilian catfish, Hypostomus regani

    SC Cohen

    2001-05-01

    Full Text Available The surface topography and ultrastructure of the tegument of Paranaella luquei Kohn, Baptista-Farias & Cohen, 2000, a microcotylid monogenean parasite from the gills of Hypostomus regani (Ihering, 1905 (Loricariidae was studied by scanning (SEM and transmission electron microscopy (TEM. By SEM, it was observed that the tegument presents transversal ridges, forming folds in the ventral and dorsal surfaces and microvillous-like tegumental projections in the anterior and median regions of body. These projections were also observed by TEM. The tegument is made up of a syncytium delimited by apical and basal plasma membranes, containing inclusion bodies and mitochondria, connected to the nucleated region by means of cytoplasmatic processes. The tegumental cells present a well developed nucleus and cytoplasm containing inclusion bodies, similar to those found on the external layer, mitochondria, rough endoplasmatic reticulum and free ribossomes.

  4. Preparation and Loading Process of Single Crystalline Samples into a Gas Environmental Cell Holder for In Situ Atomic Resolution Scanning Transmission Electron Microscopic Observation.

    Straubinger, Rainer; Beyer, Andreas; Volz, Kerstin

    2016-06-01

    A reproducible way to transfer a single crystalline sample into a gas environmental cell holder for in situ transmission electron microscopic (TEM) analysis is shown in this study. As in situ holders have only single-tilt capability, it is necessary to prepare the sample precisely along a specific zone axis. This can be achieved by a very accurate focused ion beam lift-out preparation. We show a step-by-step procedure to prepare the sample and transfer it into the gas environmental cell. The sample material is a GaP/Ga(NAsP)/GaP multi-quantum well structure on Si. Scanning TEM observations prove that it is possible to achieve atomic resolution at very high temperatures in a nitrogen environment of 100,000 Pa. PMID:27026281

  5. Analytical Scanning and Transmission Electron Microscopy of Laboratory Impacts on Stardust Aluminium Foils: Interpreting Impact Crater Morphology and the Composition of Impact Residues.

    Kearsley, A T; Graham, G A; Burchell, M J; Cole, M J; Dai, Z R; Teslich, N; Chater, R; Wozniakiewicz, P A; Spratt, J; Jones, G

    2006-10-19

    The known encounter velocity (6.1kms{sup -1}) between the Stardust spacecraft and the dust emanating from the nucleus of comet Wild 2 has allowed realistic simulation of dust collection in laboratory experiments designed to validate analytical methods for the interpretation of dust impacts on the aluminium foil components of the Stardust collector. In this report we present information on crater gross morphology, the pre-existing major and trace element composition of the foil, geometrical issues for energy dispersive X-ray analysis of the impact residues in scanning electron microscopes, and the modification of dust chemical composition during creation of impact craters as revealed by analytical transmission electron microscopy. Together, these observations help to underpin the interpretation of size, density and composition for particles impacted upon the Stardust aluminium foils.

  6. Defect detection and size estimation in billet from profile of time-of-flight using ultrasonic transmission method with linear scanning

    Miyamoto, Ryusuke; Mizutani, Koichi; Ebihara, Tadashi; Wakatsuki, Naoto

    2015-07-01

    In this study, defect detection and size estimation in billet by transmission method with linear scanning were carried out and the validity of the method was evaluated by numerical simulation. In addition, the suitable signal frequency and aperture of transducers were clarified. As a result, the following were found: a defect can be detected, signals with frequencies lower than those generally used in conventional ultrasonic testing (i.e., 0.5-1.5 MHz) are desirable, and the time-of-flight (TOF) deviation Δτ becomes largest when the wavelength at center frequency and the aperture of transducers are comparable. Defect size can be estimated when a single defect exists alone and the defect is not near the surface of a billet. Although defect size estimation becomes difficult when the defect is near the surface of a billet, the defect can be detected by our proposed method.

  7. Deciphering the physics and chemistry of perovskites with transmission electron microscopy.

    Polking, Mark J

    2016-03-17

    Perovskite oxides exhibit rich structural complexity and a broad range of functional properties, including ferroelectricity, ferromagnetism, and superconductivity. The development of aberration correction for the transmission electron microscope and concurrent progress in electron spectroscopy, electron holography, and other techniques has fueled rapid progress in the understanding of the physics and chemistry of these materials. New techniques based on the transmission electron microscope are first surveyed, and the applications of these techniques for the study of the structure, chemistry, electrostatics, and dynamics of perovskite oxides are then explored in detail, with a particular focus on ferroelectric materials. PMID:26762871

  8. Scanning system

    An improved transversally cutting radionuclide scanning system is described which can be used for medical diagnosis and medical treatment of men, particularly, for brain investingations. 99mTc43 is named as a radionuclide. The device described is more sensitive, and displays results in a shorter period of time than devices known until now. By means of laser emitting diodes a continuous transmission and collection of signals is obtained, due to a rotating picture framework of offset and meshing detectors surrounding completely the scanning field around a single rotation axis - coaxialy with the axis of the head. Signals are processed and displayed by a connected computer. Description in detail, 7 figures. (UWI)

  9. A Scanning Transmission X-ray Microscopy Study of Cubic and Orthorhombic C3A and Their Hydration Products in the Presence of Gypsum

    Vanessa Rheinheimer

    2016-08-01

    Full Text Available This paper shows the microstructural differences and phase characterization of pure phases and hydrated products of the cubic and orthorhombic (Na-doped polymorphs of tricalcium aluminate (C3A, which are commonly found in traditional Portland cements. Pure, anhydrous samples were characterized using scanning transmission X-ray microscopy (STXM, X-ray photoelectron spectroscopy (XPS and X-ray diffraction (XRD and demonstrated differences in the chemical and mineralogical composition as well as the morphology on a micro/nano-scale. C3A/gypsum blends with mass ratios of 0.2 and 1.9 were hydrated using a water/C3A ratio of 1.2, and the products obtained after three days were assessed using STXM. The hydration process and subsequent formation of calcium sulfate in the C3A/gypsum systems were identified through the changes in the LIII edge fine structure for Calcium. The results also show greater Ca LII binding energies between hydrated samples with different gypsum contents. Conversely, the hydrated samples from the cubic and orthorhombic C3A at the same amount of gypsum exhibited strong morphological differences but similar chemical environments.

  10. Measurement of indium concentration profiles and segregation efficiencies from high-angle annular dark field-scanning transmission electron microscopy images

    We investigated segregation of indium in an InxGa1−xAs/GaAs heterostructure via high-angle annular dark field-scanning transmission electron microscopy (HAADF-STEM), where contrast strongly depends on the nuclear charges of the scattering atoms (Z-contrast). Indium concentration maps have been deduced from HAADF-STEM images by comparing normalized measured intensities with multislice simulations in the frozen lattice approach. Segregation coefficients were derived following the segregation model of Muraki et al. [1]. This is demonstrated for HAADF-STEM images recorded in [100] and [110] zone-axes. Determined indium concentrations and segregation coefficients are compared with results from composition analysis by lattice fringe analysis (CELFA) measurements and energy-dispersive X-ray analysis (EDX). - Highlights: • We measured the indium concentration in an InGaAs/GaAs heterostructure by HAADF-STEM. • Multislice calculations are carried out for [100] and [110] electron beam direction. • [110] beam direction is better suited for concentration analysis. • Segregation efficiencies are derived from concentration profiles. • HAADF-STEM results are compared to CELFA measurement