bluuebunny/crossref_metadata_2025_split huggingface dataset:
Application of parallel recorded EELS to analysis of beam-sensitive organic compounds
Authors: Leapman R.D. 
Published: June 2020

Electron energy loss spectroscopy (EELS) is the optimum technique for studying specific mass loss of light elements from organic compounds under irradiation in the electron microscope. The recent availability of parallel detection systems has provided a factor of approximately 1000 improvement in detection efficiency compared with serial detection. This implies a corresponding reduction in recording time or a reduction in the electron dose needed to obtain sufficient counting statistics for elemental detection. In addition, parallel detection allows us to perform “real-time” EELS, i.e. to observe the actual decay of characteristic peaks in the spectrum.EELS spectra have been recorded with a Gatan model 607 spectrometer fitted with a Gatan model 666 parallel detector based on a 1024 channel photodiode array. Data were transfered to a Tracor Northern TN5500 analysis system for display and processing. Samples were examined at 100 keV beam energy in a Hitachi H700H electron microscope operated in the TEM mode at 1000X to 10000X magnification and with a 30 mrad collection semi-angle defined by the objective aperture.
Identification of dislocations on crystal surfaces
Authors: Peng L.-M. , Cowley J.M. , Hsu Tung 
Published: June 2020

A dislocation, when meeting an external crystal surface, will result in the re-arrangement of surface atoms because of the strain field associated with it. For a free surface further complication comes from the requirement that no forces can act on the surface. The displacement field is then a superposition of the displacement field from the dislocation in an infinite crystal and from the surface stress relaxation that cancels the stress field from the dislocation on the surface. The general case for a straight dislocation of arbitrary Burgers vector and arbitrary emerging angle in a semi-infinite, elastically isotopic medium has been solved by Yoffe, and this general solution has been used in our calculations.In the technique of reflection electron microscopy (REM) an electron beam is incident on the surface. The reflection electron imaging is extremely sensitive to any deviation from a perfect surface, and therefore provides a ideal method of observing the surface dislocations.
Interfaces and substructures in copper-based shape memory alloys
Authors: Perkins Jeff , Wu M. H. , Adachi K. 
Published: June 2020

The delineation of interfaces and substructures by conventional transmission electron microscopy is reviewed for three different transformations of interest in copper-based shape memory alloys.The first case considers the interfacial structure of martensite plate boundaries in a Cu-14.6Zn-16.1Al (atomic %) alloy. The detailed structure of such interfaces is important to their relative mobility in shape memory alloys. One-dimensional lattice images such as seen in Fig. 1 help to model the effect of substructural features in the martensite on the atomistic structure and so the mobility of such boundaries1. In the example shown, the presence of very thin structural faults with a 2H structure are detected within an otherwise 18R martensite plate.The second case describes the interaction of the state of parent phase order with the structure of bainite plates formed upon isothermal aging at 150-350 C in a Cu-27Zn-4Al (weight %) alloy . Two types of atomic ordering occur in the parent phase and tend to be inherited by the bainite transformation product.
Examination of CaO-Dy2O3 for potential use as a high-temperature transformation toughening System
Authors: Fleming M. M. , Kriven W. M. 
Published: June 2020

Similarities exist between the tetragonal to monoclinic transformation of ZrO2 and the monoclinic (B) to cubic (C) transformation of Dy2O3. On cooling the transformation occurs at 1950°C and is accompanied by an 8 % volume increase which causes shattering of bulk specimens. The transformation can be suppressed, however, by minor additions of CaO. An attempt was made to fabricate a “PSD” analogue to partially stabilized zirconia (PSZ).As-received and chemically precipitated powders of pure Dy2O3 were mixed with CaO (0 to 25 mol%), uniaxially and cold isostatically pressed, sealed in small Mo crucibles and sintered at various temperatures (1900° or 1650°C) and times before cooling or subsequent annealing treatments. Some pellets were annealed in the two phase (B + C) region at 1700°C for 2 hours before quenching. Specimens were examined by XRD, TEM, EDS, HVEM, and STEM.A fast quenching in combination with the =8 mol% CaO additions were found to be essential for retention of the high temperature B phase down to room temperature.
Digital restoration of ADF-STEM images
Authors: Kirkland Earl J. 
Published: June 2020

Frieden and Wells have derived a maximum likelihood (ML) image restoration algorithm that accurately models the noise in each image element using Poisson counting statistics. This method also leads naturally to “maximum entropy” like ideas. They have reported a rather dramatic resolution enhancement when this method was applied to low light level astronomical images in which the image noise was essentially due to photon counting statistics. This low light level situation also accurately models the ADF (annular dark field) STEM (scanning transmission microscope) image if the image is aquired digitally by electronically counting the individual scattered electrons for each position of the focused probe.The simplest ADF-STEM image model assumes that the electron intensity distribution in the focused probe is the incoherent point spread function (psf) of the image.where g(x)=recorded image, f(x)=ideal image, n(x)=random noise, * represents convolution and
The maximum-likelihood method for EM autoradiography: Evaluation and comparison to cross-fire-analysis
Authors: Roysam Badrinath 
Published: June 2020

Electron microscopic autoradiography is of growing importance as a technique for the quantification of radiolabelled biochemicals in subcellular structures. In this paper, we present the results of a series of experiments that evaluate the Maximum-Likelihood (ML) method of Miller et al. and compare its performance with the well-known crossfire (CF) method.We used the ML and CF methods to analyze a common set of 48 different simulated micrographs (Fig.1) at 5 different grain-counts and 3 different Half-Distances (HDs) for a point-spread modelling H. The CF method was implemented ideally to correspond to the use of an uncountably infinite number of mask points. The count-levels and HDs were chosen to span the range of realistic values. The experiments were repeated a large number of times and the ensemble signal-to-noise ratio (ESNR), measured in decibels (dB) was computed and used as an average performance measure. A 3dB performance improvement in ESNR amounts to a doubling of accuracy.
Digital image processing methods applied to the study of annealing time on semiconductor-metal eutectic composites
Authors: Hefter J. 
Published: June 2020

Semiconductor-metal composites, formed by the eutectic solidification of silicon and a metal silicide have been under investigation for some time for a number of electronic device applications. This composite system is comprised of a silicon matrix containing extended metal-silicide rod-shaped structures aligned in parallel throughout the material. The average diameter of such a rod in a typical system is about 1 μm. Thus, characterization of the rod morphology by electron microscope methods is necessitated.The types of morphometric information that may be obtained from such microscopic studies coupled with image processing are (i) the area fraction of rods in the matrix, (ii) the average rod diameter, (iii) an average circularity (roundness), and (iv) the number density (Nd;rods/cm2). To acquire electron images of these materials, a digital image processing system (Tracor Northern 5500/5600) attached to a JEOL JXA-840 analytical SEM has been used.
A transmission electron microscopic study of ceramic superconducting thin films prepared by laser deposition
Authors: Hwang D. M. , Nazar L. , Wu X. D. , Inam A. , Venkatesan T. 
Published: June 2020

Many applications of the new high temperature ceramic superconductors require the materials to be prepared in a thin film form. The substrates play an essential role in the superconducting properties of these films. In order to optimize the critical temperatures and currents of the films and to search for new suitable substrates of desirable properties, it is important to understand the interfacial interaction between the films and the substrates. TEM studies of the cross-sectioned specimens are indispensable in providing such information.In this paper, we describe the microscopic structures of two types of Y-Ba-Cu-O thin films deposited on SrTiO3 substrates with a KrF excimer laser. The high-temperature-processed specimens are deposited at 450 C in vacuum and post-annealed for 1 hr at 900 C in an oxygen atmosphere. The low-temperature-processed specimens are deposited at 650 C in an oxygen pressure of 5 mTorr, and post-annealed for 3 hr at 450 C in an oxygen atmosphere.
Composition variations near grain boundaries in YBa2Cu3O7-δ
Authors: Babcock S.E. , Kelly T.F. , Larbalestier D.C. 
Published: June 2020

Detailed electromagnetic characterization of samples of YBa2Cu3O7-δ (123) have shown this material, at least in its sintered form, is composed of islands of good superconductor which are separated from one another by “weak links” consisting of regions of poor superconductor or normal material. A number of researchers have suggested that these weak links are associated with grain boundaries. Therefore, conventional transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) coupled with energy dispersive x-ray analysis (EDAX) have been used to investigate the morphology, crystallography, and composition of typical grain boundaries in this material.The electromagnetic properties of the specific samples from which the TEM specimens were prepared had been studied in detail. Briefly, these samples possessed relatively low normal state resistivities and nearly field independent transport critical current densities, indicating that they were of relatively high quality.For these initial studies, specimens for TEM and STEM/EDAX were prepared by dimpling plus ion milling (3-4kV, 0.5mA per gun, liquid nitrogen cooled stage).
SEM mounts coated with evaporated carbon
Authors: Stoner John O. 
Published: June 2020

In x-ray studies, interferences from metallic components in SEM mounts are usually avoided by use of carbon mounts or coverings on aluminum mounts. Carbon planchets, beryllium planchets and carbon paints are used as such coverings.Such methods for avoiding x-ray characteristic lines have disadvantages: Carbon mounts are fragile and slippery. Planchets and paint represent additional handling; paints introduce volatiles into the microscope.We have tested evaporated carbon coatings on aluminum specimen mounts in an attempt to remove these difficulties. Spectrographically pure graphite was evaporated onto cleaned aluminum specimen mounts. Several different carbon thicknesses were tested for efficacy in reducing the aluminum K x-ray emission.The best results were obtained with coatings having thickness of at least 5 micrometers (Fig. 1). Simple calculations verified that this thickness was sufficient to stop completely the electron beam at 20 keV. Spectra of coated mounts showed primarily a slowly varying bremsstrahlung background.
Scanning tip microscopies: An overview and some history
Authors: Clayton Teague E. 
Published: June 2020

The generic concept of scanned tip microscopy is much the same as the conventional scanning electron microscope. Both provide a one-to-one mapping between a point sampling of some physical property of a probe-sample surface interaction and a corresponding point in an image. Correspondence between points on the sample surface and image points is achieved by synchronizing the image generation process with probe motion. Probe motion is generally in a rastered or boustrophedon path over a selected area of the sample (Fig.1). A very lucid description of this generic microscope concept is given in a paper by Matey and Blanc. The major differences with tip microscopy methods are that no lenses are used, probe motion relative to the specimen is produced mechanically, and the probe is a solid material.Although the roots of scanned tip microscopy extend back almost twenty years to the work of Williamson with diamond styli and Young et al.
Some instrumental aspects of single atom microscopy
Authors: Kopf D. , Utlaut M. , Crewe A.V. , Isaacson M. , Mankawich W. 
Published: June 2020

We have indicated in previous publications that a scanning transmission electron microscope (STEM) capable of atomic resolution may be a useful instrument for surface science studies and, in particular, capable of observing the distribution and diffusion of single heavy atoms on thin film substrates (1-3). In our previous work, we have used a microscope which was primarily oriented towards biological work and had a very simple optical system (only an electron gun plus an objective lens (4)). This limited the flexibility with which optical conditions would be changed. Moreover, the stringent requirements for atom imaging were not necessarily compatible for routine biological electron microscopy. Thus, we decided to shift our physical experiments in atom microscopy to another, more versatile instrument.This instrument is a modified version of a 100 keV STEM which has been described before (5). The basic system is indicated schematically in figure 1. It consists of a 3 cm Butler gun followed by a condensor lens, an objective lens and a projector lens (or in recent parlance, a “post specimen” lens).
Crossed lenses for electron-microscopic devices
Authors: Baranova L.A. , Petrov I.A. , Yavor S.Ya. 
Published: June 2020

Efforts directed towards perfecting the contemporary electron-microscopic devices require improvements in quality of focusing elements, creation of high-parameter lenses, together with tendency to greater simplicity in design. One of possible solutions of this problem is the employment of electrostatic crossed lenses giving high-quality image and possessing high production effectiveness /1,2/. The electrodes of this lens consist of flat plates with apertures. The apertures are oblong in shape, e.g. rectangular. The electrodes are aligned along the optical axis, with the apertures of the adjacent electrodes positioned at 90° to each other.Fig. 1 shows a single crossed lens. Such a lens is astigmatic, it converges charged particles in one direction and diverges them in the perpendicular direction. If the middle-electrode potential is lower than the potential of the extreme electrodes, then the lens converges electrons in the direction of elongation of the apertures of the extreme electrodes. With change in polarity of the electrodes, the converging and diverging planes exchange places.
Electron optical experiments with a magnetic imaging filter
Authors: Krahl D. , Herrmann K.-H. , Kumath W. 
Published: June 2020

In the CTEM, imaging filter systems consisting of several magnetic prisms permit the removal of inelastically scattered electrons. Such systems transfer the diffraction plane and the intermediate image stigmatically. A prerequisite for a singly achromatic imaging is that the filter produces a radial intermediate image in its plane of symmetry.The symmetry relations of the magnetic fields and the electron paths permit correction of the second-order distortion and of the second-order aperture aberration [1]. The aperture-dependent magnifications, however, remain uncompensated. These aberrations must be tolerated for filter systems which have stigmatic intermediate images [2], If, however, line foci exist between the prisms, hexapoles can be applied for correction (Fig. 1 [3,4]). Such corrections seem imperative in filters which are used for high resolution electron microscopy.The adjustment of a symmetric optical path in our filter system by means of quadrupoles can be controlled by inserting an edge into the symmetry plane and simultaneously observing the image produced by the filter.
The DQE of an electron image recording system
Authors: Herrmann K.-H. , Krahl D. , Rust H.-P 
Published: June 2020

The high detection quantum efficiency (DQE) is the main requirement for an imagerecording system used in electron microscopy of radiation-sensitive specimens. An electronic TV system of the type shown in Fig. 1 fulfills these conditions and can be used for either analog or digital image storage and processing [1], Several sources of noise may reduce the DQE, and therefore a careful selection of various elements is imperative.The noise of target and of video amplifier can be neglected when the converter stages produce sufficient target electrons per incident primary electron. The required gain depends on the type of the tube and also on the type of the signal processing chosen. For EBS tubes, for example, it exceeds 10. The ideal case, in which all impinging electrons create uniform charge peaks at the target, is not obtainable for several reasons, and these will be discussed as they relate to a system with a scintillator, fiber-optic and photo-cathode combination as the first stage.
Electron microscopy of nuclear etch tracks in solids
Authors: Vuković J. , Antanasijević R. , Todorović Ž. 
Published: June 2020

A little over a ten years since the track etch method for ionizing particles in dielectric solids was introduced by R.Fleischer, P. Price and R.Walker (1,2). Some our results was presented at 2nd Balkan Congress on Electron Microscopy (3).In this communication we have investigated solid state nuclear track detectors (SSNTD): cellulose nitrate-CN (domestic product), polycarbonate-PC (“Makrofol”) and crystals of mineral auripigment (As2S3) in order of alpha and fission tracks dating.In CN and PC film a charged particle leaves a radiation damage-a latent track which is etched with H2O solution of NaOH in order to be visualized. For detailed analysis of such a track-etch pit we have used TEM for CN layers 3-4 microns thick and direct observation at 80-100kV (Fig.l). Tracks may be well shown also by the usual replication technique (Fig.2). The whole interior of the etched alpha track as well as the transparent carbon shell, is well recognized.
SEM and TEM investigation of VPE layer structure for Gap light emitting diodes
Authors: Darby D.B. , Palolil J. , Booker G.R. 
Published: June 2020

A basic problem associated with the fabrication of GaP LEDs is the high dislocation density present in GaP VPE layers grown on GaP LEC substrates, which is detrimental to device performance. Most of the layer dislocations originate from loops present in the substrate that intersect the substrate surface when growth commences. This paper is concerned with an experiment designed to reduce the dislocation density in the layer by deliberately introducing lattice strains during the growth.An experimental structure was prepared comprising a substrate cut 10° off the [100] axis, onto which was grown a layer 17μm thick doped with 2 × 1019 cm-3 of N atoms, followed by a layer 30μm thick undoped. The N causes a crystallographic mismatch at the two interfaces, and it was anticipated that some of the dislocations propagating through the first layer would bend around so as to lie along the second interface.
Interface structure and Schottky barrier height of silicade-silicon contact
Authors: Tu K.N. , Ohdomari I. , Libertini S.H. 
Published: June 2020

At present most rectifying contacts in integrated Si devices are made of transition metal silicides such as Pd2Si and PtSi. The electrical potential difference across a metal to semiconductor rectifying contact is called Schottky barrier. While many theories and studies have been devoted to increase our understanding of the origin and details of Schottky barrier, we find very little effort has been given to correlate the electrical barrier and the metal-semiconductor interface structure. We expect that there exists such a structure-property correlation and we report here our preliminary finding of the correlation in Pd2 Si contacts to n-type Si.Silicon wafers used here were n-type, 10 to 20 Ω-cm, both (111) and (001) oriented, 1 or 1 1/4" in diameter, and HF-etched before Pd deposition. For the structural study, a 800ÅPd film was e-beam evaporated in a vacuum of 10-7 torr onto the Si kept at various substrate temperature, Ts, shown in Table I
Electron micro-densitometry during in-situ TEM investigations
Authors: Heinemann Klaus , Poppa Helmut 
Published: June 2020

An electron detector with small detection area for use in the final image plane of a transmission electron microscope has been commercially offered by TEM manufacturers (1). However, little has been reported about the application of such a device. In this report, the construction principle and the operation of a novel microdensitometry device is described which combines precision image point selection with versatility, high sensitivity, ease of operation, and comparatively low cost.The electron microdensitometer system consists of a transparent phosphor screen onto which the electron image is projected, a small “channeltron” electron multiplier (supplied by Galileo/Bendix) underneath, and a closed-circuit TV system (Fig.l). The screen has an effective diameter of 45 mm and contains a 2 mm concentric hole which allows a small beam of electrons to pass unobstructed to the electron multiplier. The multiplier consists of a 3 mm O.D. tube in custom L-shaped configuration and is mounted such that its collector is located outside the screen area to minimize obstruction of the image viewed on the TV monitor.
Incoherent illumination method with conventional electron microscope
Authors: Nagata Fumio , Matsuda Tsuyoshi , Komoda Tsutomu , Hama Kiyoshi 
Published: June 2020

When fine details of thin films are observed, the image are generally composed of both amplitude and phase contrast. The image resolution is sometimes limited by the granular background noise of supporting film which is due to the phase contrast effect by fairly coherent illumination(CI).In the present work, incoherent illumination(ICI) method has been studied to avoid the phase contrast effect using a conventional electron microscope(Hitachi HU-12A).The ICI method was made by enlarging the illumination angle(β) to be equivalent to the glancing angle(α=1.4x10-2 radians) of objective aperture. The large angle illumination was achieved by the strong excitation of an objective lens.At first, the properties of phase contrast in ICI image were studied as functions of beam divergence angle and defocus using a carbon film. Both analytical and experimental investigations show that the granular noise in a phase contrast image decreases as β is increased from l×l0-4 to l×l0-2radians.
Atomic resolution from 500kv electron micrographs by computer image processing
Authors: Uyeda N. , Kirkland E. , Fujiyoshi Y. , Siegel B. 
Published: June 2020

We have successfully applied the method suggested by P. Schiske (1) for optimally combining several micrographs of different defocus values (Δfβ) in the presence of additive noise. If c(k) represents the Fourier transform of tne ideal, unaberrated bright field image, and jβ(k) the transform of the real micrographs obtained at different defocus values, then the filter functions Qβ(k) that reducesto a minimum, was shown (1) to be, within a common multiplicative factor,The contrast transfer function (CTF) is where λ is the electron wavelength and Cs is the spherical aberration coefficient of the objective lens. η(k) is the noise to signal ratio in reciprocal space for unit CTF.This procedure was applied to images of a tilted crystaline specimen of hexadecachloro- phtalocyanatocopper (II) taken on the Kyoto 500KV electron microscope (2).