bluuebunny/crossref_metadata_2025_split huggingface dataset:
Towards quantitative simulations of inelastic electron diffraction patterns and images
Authors: Wang Z. L. 
Published: June 2020

A new dynamical theory has been developed based on Yoshioka's coupled equations for describing inelastic electron scattering in thin crystals. Compared to existing theories, the primary advantage of this theory is that the incoherent summation of the diffracted intensities contributed by electrons after exciting vast numbers of different excited states has been evaluated before any numerical calculation. An additional advantage is that the phase correlations of atomic vibrations are considered, so that full lattice dynamics can be combined in the phonon scattering calculation. The new theory has been proven to be equivalent to the inelastic multislice theory, and has been applied to calculate energy-filtered diffraction patterns and images formed by phonon, single electron and valence scattered electrons.A calculated diffraction pattern of elastic and phonon scattered electrons for a parallel incident beam case is in agreement with the one observed (Fig. 1), showing thermal diffuse scattering (TDS) streaks and Kikuchi pattern.
Quantitative strain and structure factor phase measurement by cbed.
Authors: Spence J.C.H. , Zuo J.M. 
Published: June 2020

CBED is highly efficient - a large amount of quantitative information is obtained from an extremely small volume. Different regions of the pattern contribute different kinds of information. Outer reflections and HOLZ line intensities may be refined for atomic positions and temperature factors, inner reflections for bonding effects, and HOLZ line positions for lattice parameters and strain. Recently we have automated the process of comparing elastically filtered intensities with Bloch-wave and dynamically corrected kinematic computations by combining them with the “Simplex” leastsquares refinement algorithm, as used in the Reitvelt method. Adjustable parameters may be structure factors, cell constants, atomic position parameters etc. Perturbation methods are used for weak beams and error matrix elements.Strains due to oxygen disorder near a grain boundary in YB2Cu3O7-x have been measured on a 2 nm scale with an accuracy of 0.015% using HOLZ line intersection measurements. From these, the oxygen deficit x may be mapped out. A CBED pattern near [0-12] was recorded using an EM400ST FEG microscope and digitized into SEMPER.
Quantitative analysis of diffuse scattering with imaging plate
Authors: Shindo D. , Ohishi T. , Iijima S. , Hiraga K. , Oikawa T. , Kerskei M. 
Published: June 2020

The excellent properties of the imaging plate (IP), i.e., a wide dynamic range and good linearity for the electron intensity, are promising for quantitative analysis of diffuse scattering since they allow a small dynamical diffraction effect to be evaluated with ‘dynamical factor’. In this paper, we first present accurate measurement of thermal diffuse scattering (TDS), which contributes dominantly to the background of electron diffraction patterns. Secondly, we present a method of extracting weak signal scattering intensities from the background, and apply it to the analysis of diffuse scattering caused from short-range ordered structures.Electron microscope images were obtained with a JEM-2000EXII electron microscope. Image processing was carried out by using a computer system (ACOS 2020) at Tohoku University. Electron diffraction patterns were recorded by using the TEM-IP system (PIXsysTEM). The details of the IP data handling were presented in the previous paper.Figure 1 shows an electron diffraction pattern obtained from an Au thin film ( t ∼ 40nm) at room temperature.
Imaging dislocations with an annular dark-field detector
Authors: Liu J. , Cowley J. M. 
Published: June 2020

High-angle annular dark-field (HAADF) scanning transmission electron microscopy (STEM) has been recently the subject of active research because of its successful applications to the characterization of supported catalysts, interface problems in MBE grown semiconductors, superconductors and X-ray multilayers. The characteristics of HAADF images are different from those of the TEM images. For perfect single crystals the HAADF signal is mainly generated from thermal diffuse scattering. HAADF technique has also been used to study dopant contrast effects in semiconductors and dislocations have also been observed with an ADF detector. In this paper we report a study of dislocation contrasts and their dependence on the inner collection angle of the ADF detector.The STEM instrument used for the observations was the HB5 from VG Microscopes, Ld., modified by the addition of an ultra-high resolution pole piece (Cs = 0.8 mm) and a two-dimensional detector system. Post specimen lenses and various beam stops were used to change the inner (α) and outer (β) collection angles of the ADF detector.
Corrections for surface films in microanalysis by EDS and EELS
Authors: Bentley J. , Kenik E. A. 
Published: June 2020

Common artifacts on analytical electron microscope (AEM) specimens prepared from bulk materials are surface films with altered structure and composition that result from electropolishing, oxidation, hydrocarbon contamination, or ion milling (preferential sputtering or deposition of sputtered specimen or support material). Of course, the best solution for surface films is to avoid them by improved specimen preparation and handling procedures or to remove them by low energy ion sputter cleaning, a capability that already exists on some specialized AEMs and one that is likely to become increasingly common. However, the problem remains and it is surprising that surface films have not received more attention with respect to composition determination by energy dispersive X-ray spectrometry (EDS) and electron energy loss spectrometry (EELS).For EDS, an effective first-order correction to remove the contribution of surface films on wedge shaped specimens is to subtract from the spectrum of interest a spectrum obtained under identical conditions (probe current, diffracting conditions, acquisition live time) from a thinner region of the specimen.
A data base for energy loss cross sections and mean free paths
Authors: Egerton R.F. 
Published: June 2020

For quantitative elemental analysis by standard EELS techniques, we require inner-shell cross sections integrated over an energy range Δ beyond the ionization edge. These cross sections are conveniently parameterized in terms of a dipole oscillator strength f(Δ) which is independent of incident energy Eo and collection semi-angle β.Values of f(Δ) are obtainable from EELS measurements, from theoretical models and from photoabsorption data. Compilation of this data allows one to obtain a best estimate of a given cross section, together with an estimate of the probable error. Consistency is good for K-shells, allowing f(Δ) to be predicted to within 5% accuracy. At the opposite extreme, discrepancies of an order of magnitude exist for the N- and O-shells (Fig.1). In general, there is more consistency with regard to edge shape, as expressed by the ratio ϕ(Δ)=f(Δ)/f(100); see Fig.2.If microanalysis is carried out by matching to stored edge profiles, the convenient quantity is the differential oscillator strength df/dE. Such data is available directly from atomic calculations and, for some edges, from experimental measurements; see Fig.3.
Characterization of metamict and glassy phosphates using energy-filtered electron diffraction
Authors: Sreeram A. N. , Qin L. C. , Garratt-Reed A. J. , Hobbs L. W. 
Published: June 2020

Lead phosphate glasses have been investigated for decades with respect to fundamental glass properties such as glass transition, devitrification, electrical and optical properties. In these glasses, [PO4] tetrahedra, (like [SiO4] tetrahedra in silicates) can link up together by corner sharing oxygen atoms to form polymerized structures upto and including three dimensional glassy networks. Although, little electron diffraction data on amorphous phosphates is available, radial distribution functions have been generated for lime phosphate glasses and amorphous aluminum phosphates using x-ray diffraction techniques. More recently, Sales et al. have examined near surfaces of single crystals of lead pyrophosphate (Pb2P2O7), rendered aperiodic (metamict) by ion implantation, and lead pyrophosphate glass using high-performance liquid chromatography (HPLC), making use of the fact that condensed phosphates do not alter their state of polymerization when dissolved in aqueous solutions.In our studies, single crystals of Pb2P2O7 were found to be beam stable under 200 keV TEM electrons to an electron fluence > 1027 e/m2 and an ionizing dose > 1014 Gy. This negative radiolytic result leaves ballistic displacement by ions or neutrons as the only route to render the samples metamict.
High-Magnification in-lens field-emission SEM of sectioned biological material
Authors: Apkarian R.P. , Scala C. , Pasquinelli G. 
Published: June 2020

Osmium macerated renal specimens are rich in SE-I contrasts at very high magnifications when the ultrathin Chromium (Cr) film/intermediate voltage (15-30 kV) imaging strategy is employed. This technique enables imaging of minute particle domains which contain SE-I edge brightness contrast when staged in an in-lens field emission scanning electron microscope (SEM). The utility of employing methylmethacrylate embedded and sectioned specimens, that were subsequently acetone deembedded and critical point dried on silicon chips, was that they were rendered ideal for ultrahigh resolution SEM studies. The section/SEM method provided an exellent correlate to light microscopy (LM) and transmission electron microscopy (TEM) and may extend topographic image resolution within tissues to the molecular level.Rat kidney was briefly fixed in 0.5% glutaraldehyde/ 0.5% formaldehyde, postfixed in 1.0% OsO4 and osmium macerated (0.1%) prior to the embedding/sectioning/deembedding/drying procedures. Kidney sections ranging from 80 nm to 1.5 μm on silicon chips were thoroughly degassed and coated with a 1 nm fine grain Cr film in a Denton DV-602 sputter system.
Secondary-Electron imaging by Scintillating Gaseous Detection Device
Authors: Danilatos G. D. 
Published: June 2020

The environmental scanning electron microscope (ESEM) incorporates the functions of the conventional SEM while it has the added capability of allowing the examination of virtually any specimen in a gaseous environment. The main modes of imaging are all represented in the ESEM, and some developments with regard to the secondary electron (SE) mode are reported herewith.The conventional E-T detector fails to operate in the gaseous conditions of ESEM, but this obstacle has been overcome with the advent of a gaseous detection device (GDD). The principle of operation of this device is based on the monitoring of the products of interaction between signals and gas. Initially, the ionization from the signal/gas interaction was used to produce images of varying contrast and, later, the gaseous scintillation, from the same interaction, was also used to produce images. First, a low bias was applied to various electrodes but later a much higher bias was used for the purpose of achieving additional signal gain. By careful shaping and positioning the respective electrode, it was shown that SE imaging is possible in the ESEM. This has been also independently demonstrated by use of a special specimen preparation.
Advantages of Complementary Stereo Images as Viewed with the Low-Temperature Field-Emission SEM
Authors: Wergin William P. , Erbe Eric F. 
Published: June 2020

The eye-brain complex allows those of us with normal vision to perceive and evaluate our surroundings in three-dimensions (3-D). The principle factor that makes this possible is parallax - the horizontal displacement of objects that results from the independent views that the left and right eyes detect and simultaneously transmit to the brain for superimposition. The common SEM micrograph is a 2-D representation of a 3-D specimen. Depriving the brain of the 3-D view can lead to erroneous conclusions about the relative sizes, positions and convergence of structures within a specimen. In addition, Walter has suggested that the stereo image contains information equivalent to a two-fold increase in magnification over that found in a 2-D image. Because of these factors, stereo pair analysis should be routinely employed when studying specimens.Imaging complementary faces of a fractured specimen is a second method by which the topography of a specimen can be more accurately evaluated.
Environmental scanning electron microscopy of fresh human gallstones reveals new morphologies of precipitated calcium salts
Authors: Kaufman Howard S. , Lillemoe Keith D. , Mastovich John T. , Pitt Henry A. 
Published: June 2020

Gallstones contain precipitated cholesterol, calcium salts, and proteins. Calcium (Ca) bilirubinate, palmitate, phosphate, and carbonate occurring in gallstones have variable morphologies but characteristic windowless energy dispersive x-ray (EDX) spectra. Previous studies of gallstone microstructure and composition using scanning electron microscopy (SEM) with EDX have been limited to dehydrated samples. In this state, Ca bilirubinates appear as either glassy masses, which predominate in black pigment stones, or as clusters, which are found mostly in cholesterol gallstones. The three polymorphs of Ca carbonate, calcite, vaterite, and aragonite, have been identified in gallstones by x-ray diffraction, however; the morphologies of these crystals vary in the literature. The purpose of this experiment was to study fresh gallstones by environmental SEM (ESEM) to determine if dehydration affects gallstone Ca salt morphology.Gallstones and bile were obtained fresh at cholecystectomy from 6 patients. To prevent dehydration, stones were stored in bile at 37°C. All samples were studied within 4 days of procurement.
The titanic 80 years later: initial observations on the microstructure and biogeochemistry of corrosion products
Authors: Stoffyn Patricia , Buckley Dale E. 
Published: June 2020

The “Titanic 91” Expedition, carried out from the Russian Academy of Science vessel “Akademik Keldysh”, recovered artifacts from the wreck of the Titanic using the manned submersible “MIR-2”. Conspicuous corrosion products are iron rusticles resembling stalactites. These rusticles can reach lengths of several tens of cm and grow from various parts of the ship (Fig. 1). The origin of the rusticles and their relation to other corrosion products was investigated using a scanning electron microscope equipped with an x-ray energy dispersive spectrometer and a separate x-ray diffraction system.Rusticles are formed of a brittle iron oxy-hydroxide shell approximately 100 to 200 μm thick, with a smooth dark red outer surface (toward seawater) and an orange rough inner surface (toward the centre of the rusticle). The core of the rusticle and the inner surface of the shell is made of a reticular framework of spherical aggregates. The small needle-like crystals forming these aggregates (Fig. 2) are goethite (α- FeO(OH)).
Porous silicon pore filling by metal electroplating
Authors: Chuang S.-F. , Kuan T. S. , Lin K. 
Published: June 2020

Porous silicon can be used as an insulating material in Si devices and as a membrane for ion or molecule separation. Its recently demonstrated photo- and electro-luminescence properties may find novel applications in optoelectronics. Porous silicon has a large internal surface, and, with its pores filled with conducting materials, can form a capacitor with a high charge storage capacity. Recently, thin metal films have been electroplated on porous silicon substrates. These films were then detached and used as condenser microphone diaphragms. Electroplated metal films can also provide electrical contacts to an electro-luminescent porous silicon structure. In this paper, we report our TEM study of a copper electroplating process. We found that in such a process copper preferentially deposits from the bottom of the pore tips upward and fills the entire length of each pore as well as the horizontal side branches.Anodization of silicon was performed in an aqueous HF solution to form a porous layer. Silicon substrates used in this experiment were n-type, (l00)-oriented wafers with a doping concentration of 1017 cm−3 and p-type, (l00)-oriented wafers with a doping concentration of 1019 cm-3.
Specific site device failure analysis: A case history
Authors: Anderson Ron , Wall Joseph , Klepeis Stanley 
Published: June 2020

Failure analysis application of analytical TEM analysis was handicapped in the past by the difficulty associated with specimen preparation of specific devices in complicated integrated circuit arrays. We have published several papers detailing methods for preparing TEM specimens with high specimen preparation spatial resolution in periods of about two to four hours. This paper offers a case history of a TEM failure analysis that combines high spatial resolution specimen preparation and the utilization of chemical junction delineation techniques.The device failure came to light in a chip tester prior to shipment. Tester electrical diagnostics identified a particular cell within a large array as defective. The fail's electrical signature further narrowed-down the potential candidates to a small number of devices within the cell. The chip was examined in transmission in an IR microscope. Anomalous IR contrast was observed in the emitter of one bipolar device in the suspect region (Fig. 1). A series of conventional light-optical photographs, with increasing magnification, were taken to define the failure location. Using the light-optical photos as a guide, the failed emitter was bracketed with laser craters. The specimen preparation polishing operation used the laser craters to achieve a plane-of-polish through the suspect emitter.
Effects of elastic anisotropy on CTEM dislocation images in L10 alloys: An assessment of the sensitivity computed images to input parameters
Authors: Singh Abha , King A.H. 
Published: June 2020

Ordered alloys have important applications as high temperature structural materials. Grain boundary embrittlement, however, is a major obstacle in their practical applications. The details of grain boundary structure have been suggested to be important in determining the mechanical properties, and it is therefore important to have a better understanding of grain boundary structure in these alloys.Conventional g.b and g.b×U techniques for the determination of Burgers vectors of lattice and grain boundary dislocations are limited by the magnitude of the Burgers vectors and spacing of the dislocations. The dislocations may not be detected if the magnitude of the Burgers vectors is less than 0.05nm or the spacings less than one third of the extinction distance. The strengths of grain boundary dislocations are usually very small, therefore in determining the Burgers vectors of grain boundary dislocations, computer image matching techniques are generally used in conjunction with the usual g.b and g.b×U techniques.
Materials-science applications of novel methods for the analysis of electron-diffraction patterns
Authors: Carpenter G.J.C. , Le Page Y. 
Published: June 2020

Electron diffraction provides a highly effective method for the identification of microscopic, crystalline phases in the solid state. The following examples are given to illustrate applications of three new analytical methods to typical problems in analytical microscopy of materials.Phase identification using convergent beam electron diffraction (CBED) patterns can often be simplified when measurements from the zero and high order Laue zones (ZOLZ and HOLZ) are combined to calculate the primitive cell volume, Vc. Defining g1 and g2 as two primitive vectors in the ZOLZ (e.g. two non-collinear spots closest to the transmitted beam) the volume of the primitive reciprocal cell is;Vc* = g1 × g2 . H,where H is the reciprocal interplanar spacing calculated from the diameter(s) of the HOLZ ring(s). This calculation can be performed without indexing the pattern. The inverse of Vc* is the volume of the primitive cell, Vc, which is easily compared with literature data for possible phases.
Current performance limits for XEDS in the AEM
Authors: Zaluzec Nestor J. 
Published: June 2020

For nearly the last decade, the microanalysis community has heard descriptions of the expected performance benefits of intermediate voltage analytical microscope operation. While it is true that these instruments have improved image resolution and probe forming capabilities, the majority generally perform worse in terms of XEDS analytical sensitivity than their 100 kV counterparts. Figure 1 compares the performance characteristics reported by Williams and Steel in 1987 for thirteen different AEM's, with recent measurements on the ANL AAEM (VG HB 603Z). Here the experimental Cr-K Peak to Background (P/B) ratio measured from the NIST (NBS) 100 nm thin-film standard is plotted as a function of accelerating voltage. From this figure, we see that a marked improvement in the performance of the newest generation of medium voltage AEM's has finally been commercially realized.While there are several measurements of analytical sensitivity in XEDS, a convenient measure is the Minimum Mass Fraction (MMF).
Compositional imaging in biology: limits and potential
Authors: Somlyo Andrew P. , Shao Zhifeng , Somlyo Avril V. 
Published: June 2020

Compositional imaging of cells and organelles in physiological and pathological states is a major challenge and opportunity for structural biology, but its potential for revealing new and significant biological information depends on the attainable sensitivity and spatial resolution. Since most biological materials consist of “trace concentrations” of elements embedded in an organic matrix composed of carbon, nitrogen, and oxygen, the minimal detectable concentration, rather than minimal detectable mass, is often the more important criterion of sensitivity. The past two decades have seen significant progress in the application of analytical electron microscopy [AEM] to biology and, after a brief standstill, the next decade offers further significant advances.The preparatory method suitable for “high resolution” analysis of most biological materials is now well-established: rapid freezing, followed by cryoultramicrotomy and freeze drying to produce ultra thin specimens. Until recently, electron probe x-ray microanalysis and, related to it, x-ray mapping has been the most successful analytical method.
Micro-Raman spectroscopy applied to polymers
Authors: Meier Robert J. 
Published: June 2020

Over the last years micro-Raman spectroscopy has developed to a mature subdiscipline within the field of Raman spectroscopy. Its potential power seems obvious: (a) fluorescence suppression, a major obstacle in many Raman spectra; (b) micro-analysis of samples down to 1 μm lateral resolution yielding molecular information; (c) when using a confocal arrangement with the microscope, in addition to lateral resolution the depth resolution can be enhanced up to the 1 μm level.We applied micro-Raman spectroscopy over the last few years and recently developed a confocal Raman microscopic set-up. Our main application being in the field of polymers, the first thing to worry about is to what happens to the polymer sample when it is irradiated locally with a high laser power density. One should be warned even long before melting in order to avoid morphological changes because, after all, Raman spectroscopy is a powerful tool to study polymer morphology in detail. We use the Stokes/Anti-Stokes intensity ratio for determining the sample temperature.