bluuebunny/crossref_metadata_2025 huggingface dataset:
Nonmucoid gram-negativePseudomonasrods can readily be observed in cystic fibrosis patients' smears stained by the PATS reaction
Authors: Giammara B.L. , Hopfer R.L. , Hanker J.S.
Published: June 2020

Cystic fibrosis(CF) is responsible for much of the chronic pulmonary disease seen in children. Progressive pulmonary insufficiency accompanied by respiratory tract infection is the cause of death in 90% of CF patients. Although gram-positive staphylococci were responsible for most of these pulmonary infections prior to 1960, gram-negativePseudomonas aeruginosa(PA) colonization is now the major cause of the progressive pulmonary disease responsible for the morbidity and mortality in CF patients. Sputum has long been used for cultural purposes for CF patient evaluation. It has not been a good source for Gram stain specimens inasmuch as large numbers of deep blue gram-positive bacteria (Fig. 1) can overlie and mask the smaller numbers of pink or red rods such as PA which are being sought in the stained smear.
Undecagold labeling of cytochrome c oxidase dimer crystals
Authors: Crum John , Gruys Kenneth J. , Frey Terrence G.
Published: June 2020

Cytochrome c oxidase (E.C. 1.9.3.1.) is an integral inner mitochondrial membrane protein, and is the terminal electron acceptor whereby cytochrome c (reduced by ubiquinol cytochrome c oxidoreductase) is oxidized and molecular oxygen is reduced producing water. When isolated mitochondria are treated with detergents, the other proteins and most of the lipids are extracted leaving membranous cytochrome c oxidase. Depending on the amounts and types of detergents used the cytochrome c oxidase molecules may form two-dimensional crystals composed of monomers or of dimers. These two-dimensional crystals are suitable for crystallographic image processing procedures. Recently the three-dimensional structure of cytochrome c oxidase in dimer crystals has been reported to a resolution of 20 Å. Though much work has been done, the location of the cytochrome c binding site on cytochrome c oxidase has not been determined.
Quantitative correlation of immunoelectron microscopy and radioimmunoassay
Authors: D'Andrea M. , Forte M. , Chen C. , Gu J.
Published: June 2020

Indirect Immunogold electron microscopy has been widely used in biomedical research. It uses uniformly sized gold particles to label antibodies which can recognize specific tissue antigens on ultra thin sections. The method is superior to other immunoelectron microscopic procedures in that the number of good particles on antigenic sites can be counted and the results assessed comparatively. This method is not absolutely quantitative because the amounts of antigen molecules each labeling gold particle represents are not known. We developed an approach to bring a novel quantitative concept into immunoelectron microscopy (IEM) by correlating the results obtained by IEM and by radioimmunoassay (RIA). A peptide hormone, atrial natriuretic peptide (ANP) in the right atrium of the rat heart was chosen as the model because in this region this antigen is abundant and has a defined distribution, being exclusively in the specific cytoplasmic granules.
Establishment of pattern in the developing compound eye of Drosophila
Authors: Bentham W. , Poodry C.
Published: June 2020

Each compound eye of the fruitfly, Drosophila melanogaster, is composed of about 800 individual light gathering and sensing units called ommatidia. The structure of the ommatidium is the product of some twenty four cells has a corneal lens to focus light, eight photoreceptors to sense the light, and a collar of pigment cells to absorb stray light. There are also mechanosensory bristles associated with ommatidia over much of the eye. The ommatidia are normally organized in a hexagonal array so perfectly placed that it has been called a neurocrystallin lattice. A number of mutations have been isolated that disturb the order or spacing of the ommatidia thereby resulting in a rough appearing eye. The focus of this study is to understand processes at work in establishing the precise pattern of ommatidial spacing.
Ultrathin sectioning and staining artifacts in transmission electron microscopy specimen preparation
Authors: Klomparens Karen L.
Published: June 2020

Ultrathin sectioning followed by staining of sections are the final two steps in the preparation procedure for transmission electron microscope (TEM) specimens. While each requires an understanding of the scientific principles involved, these steps, perhaps more than any others, also require meticulous attention to detail and, for ultrathin sectioning, considerable skill and practice. Even with a properly fixed and infiltrated specimen in a well-polymerized block, there are a number of factors which can contribute to artifacts in ultrathin sections. Most can be corrected or at least minimized assuming that the ultramicrotome environment is well-situated; i.e., free of vibration, excessive heat, humidity, and air currents.
Slit scan illumination for dynamic focusing
Authors: Benner G. , Frey J. , Weimer E.
Published: June 2020

This mode describes a modification of the spot scan mode1 in which areas on a photographic plate are exposed one after the other using small illuminating spots. The spot scan mode in transmission electron microscopes (TEM) reduces specimen damage and specimen drift. In addition to this it allows dynamic focussing at high tilt angles of the specimen.

High-resolution, 3-D specimen reconstruction and reflection electron imaging using specimen tilt angles of up to 90° require dynamic focussing rectangular to the tilt axis of the goniometer for imaging of off-axis specimen areas. A slit-type illumination of the specimen parallel to the goniometer tilt axis may provide a better solution for such types of problems.
scanning tunneling microscope imaging of the real space structure of a two-dimensional quasicrystal
Authors: Becker R. S. , Kortan A. R. , Thiel F. A. , Chen H. S. , Becker A. J.
Published: June 2020

Quasicrystals are a new phase of condensed matter characterized by a lack of translational symmetry, while yet possessing strong orientational symmetry. From their 1984 discovery in Al-Mn by Schectman et. al. until the present, they have remained poorly understood, principally due to their lack of periodicity, which has proved to be a serious stumbling block to the traditional analytical methods of condensed matter physics. Two dimensional decagonal quasicrystals were discovered in 1985 by Bendersky. These unusual compounds are quasiperiodic in two dimensions and periodic in the third, appearing intermediate between periodic and fully quasiperiodic phases. A number of models have been advanced in explanation of the curious symmetry displayed by these materials, falling into three main categories; quasicrystal glasses, multiple twinning, and tilings, The glass models have been unable to account for the perfection shown by the Al-Cu-Fe quasicrystals, while diffraction methods have difficulty distinguishing between the latter models.
In situ high-resolution Transmission electron microscopy of interphase boundary motion in metallic alloys
Authors: Howe James M.
Published: June 2020

Information provided by in situ studies is often essential for understanding microstructural evolution in solids. The recent development of intermediate-voltage high-resolution transmission electron microscopes (HRTEM) with in situ heating capabilities now provides the opportunity to perform in situ high-resolution studies of interphase boundary (IPB) motion. This paper presents initial results on in situ HRTEM studies of IPB motion in metallic alloys, in particular, during growth of Q precipitates in an Al-Cu-Mg-Ag alloy and Pd3Si crystals in an amorphous Pd-Si alloy.

Samples of an Al-4Cu-0.5Mg-0.5Ag (wt.%) alloy were aged for 24 hr at 250°C and electropolished in a HNO3/methanol solution; samples of an amorphous Pd80Si20 (at.%) ribbon were ion milled in a liquid-nitrogen cold-stage at 6 kV, 0.3 mA and 15° tilt. The samples were examined at 400 kV in a JEOL 4000EX microscope equipped with a UHP40X hot-stage pole piece and double-tilt holder at temperatures of 200-400°C. Images were recorded on a Sony BetaCam video cassette recorder connected to a Gatan fiber-optically coupled TV camera with an image intensifier. A 35 mm camera was used to obtain photographs directly from the TV monitor during playback of the video cassettes.
Resolution in x-ray microscopes
Authors: Jacobsen C. , Kirz J. , Williams S.
Published: June 2020

X-ray microscopes can be roughly grouped into two categories: soft x-ray microscopes (λ ≈ 1-10 nm) which are able to image specimens at up to 30 nm resolution with some elemental mapping capabilities, and hard x-ray microprobes (E ≈ 3-100 keV) which are able to map trace chemical compositions and produce tomograms at ∼ 2 μm resolution. In both cases, the sample can be hydrated and in air, its thickness can be range from a few μm (with soft x rays) to a few mm (hard x rays), and the radiation dose delivered is considerably lower than what is involved in the equivalent electron microscopy technique.

Some x-ray microscopes are lensless instruments. In contact microscopy and Gabor holography, soft x rays passing through the sample are recorded directly on high resolution photoresists (e.g., PMMA). Shinozaki et al. have studied the x-ray exposure properties of PMMA in detail, and have concluded that a detector resolution limit of 20 nm or better should be attainable.
Spatial resolution in electron energy loss scattering
Authors: Batson P.E. , Leapman R.D.
Published: June 2020

Limits on the spatial resolution in electron energy loss scattering (EELS) can be classified in several different categories. First, we must consider probe-specimen interactions which are separate from the energy loss event. These produce spreading of the probe in the STEM case and intermixing of beams with different specimen paths in the TEM case. Second, the EELS event itself is dependent on details of the scattering physics. We identify two subcategories for describing this, based roughly on the amount of energy lost -- a) the low energy region including surface and bulk plasmons, and b) core excitations. Third, the statistical quality available for the measurement will degrade the resolution, particularly for core edges.
Ultimate resolution: A mathematical framework
Authors: van den Bos A.
Published: June 2020

Modern optics and electron optics literature usually associates resolution with the geometrical extension of observed intensity distributions. This agrees with Rayleigh's formulation a century ago. He considers two superimposed, incoherent, sine-square intensity distributions at a distance such that the center of the one distribution coincides with the first zero of the other and states, “We may consider this to be about the limit of closeness at which there could be any decided appearance of resolution.” Later modifications and generalizations only quantitatively differ from this limit. Clearly, Rayleigh referred to the limitations of the human visual system. Since then, photometry and numerically processing have become available. Under these new conditions, sticking to the visual Rayleigh limit leads to inconsistencies. To see this, suppose that the combined intensity distribution is exactly measured and that the component functions are exactly known like in Rayleigh's considerations. Then numerically fitting the components with respect to their intensity and locations removes any limit to resolution.
Ultimate resolution and information in electron microscopy
Authors: Van Dyck D.
Published: June 2020

An (electron) microscope can be considered as a communication channel that transfers structural information between an object and an observer. In electron microscopy this information is carried by electrons. According to the theory of Shannon the maximal information rate (or capacity) of a communication channel is given by C = B log2 (1 + S/N) bits/sec., where B is the band width, and S and N the average signal power, respectively noise power at the output. We will now apply to study the information transfer in an electron microscope. For simplicity we will assume the object and the image to be onedimensional (the results can straightforwardly be generalized). An imaging device can be characterized by its transfer function, which describes the magnitude with which a spatial frequency g is transferred through the device, n is the noise. Usually, the resolution of the instrument ᑭ is defined from the cut-off 1/ᑭ beyond which no spadal information is transferred.
EMSA/MAS standard format for spectral data exchange
Authors: Zaluzec N.J. , Kirkland E. J. , Isaacson M.S. , Hunt J. A. , Fiori C.E. , Fiori C.E.
Published: June 2020

One of the frustrating problems experimentalists often encounter with computer based spectroscopic instrumentation is the general incompatibility of the data files recorded on different analysis systems. The rapid growth of inexpensive personal computers has resulted in an information explosion which has increased the desirability and need for a simple method for exchange of experimental data between scientists who may be office neighbors or transoceanic collaborators. While it is not reasonable to expect a particular manufacturers software, which was designed and optimized for specific hardware, to function on an competitor's system, it would be of enormous value to the microanalysis community to have a simple method for data interchange. This would allow, for example, the routine distribution of experimental data between research laboratories with a minimum of difficulty or would enable test spectra to be transported between data acquisition systems to compare different data analysis routines. These points as well as all the other merits of a standardized data format have been detailed elsewhere.
A Monte Carlo calculation of the x-ray production from multilayer samples
Authors: Ly T. D. , Howitt D. G.
Published: June 2020

The X ray generation and absorption from a sample in an SEM or Electron Microprobe depends upon the geometry as well as the composition. Various schemes for calculating the X-ray signal from a homogeneous sample have been developed but few have addressed the problem associated with the presence of distinct microstructures. We have developed a Monte Carlo program to calculate the signal production from a multilayer sample as a first step to the incorporation of microstructural effects.

The X-ray production from a layered structure is different from a homogeneous sample because the signal production and absorption are discontinuous. The differences can be calculated if the layer thicknesses and positions can be taken into account. The principle behind the calculation we have undertaken is the continuously monitor the energy and position of the electron in the specimen. Each trajectory is calculated in the usual stepwise manner except that the step size and scattering probability are continuously adjusted to accommodate the scale of the microstructure.
Improving the user interface design for electron microscopy (EM) databases
Authors: Hewan-Lowe K. O.
Published: June 2020

The user interface is a critical portion of any application program. Many EM databases reside in dBASE ™, relational database management systems (RDBMS). The user interface for dBASE ™ RDBMS consists of menu choices and templates for the display of database fields. User interaction with menus and templates is by sequential keyboard input. Though the dBASE ™ RDBMS provides excellent support for database functions there is little support for the design of a functional user interface. Menus of screen choices, templates for field display and the requirement for keyboard input tend to overwhelm all but the most experienced computer user. Since most users prefer screen displays which include familiar objects, any improvement in the user interface for EM databases should seek to simulate these objects in the user interface. Because HyperPAD ™ allows the simulation of familiar objects during screen design, it is an excellent tool for constructing an improved user interface for EM databases in dBASE ™ file format.
Electron crystallographic determination of the 3-D structure of staurolite at atomic resolution
Authors: Downing Kenneth H. , Meisheng Hu , Went Hans-Rudolf , O'Keefe Michael A.
Published: June 2020

With current advances in electron microscope design, high resolution electron microscopy has become routine, and point resolutions of better than 2Å have been obtained in images of many inorganic crystals. Although this resolution is sufficient to resolve interatomic spacings, interpretation generally requires comparison of experimental images with calculations. Since the images are two-dimensional representations of projections of the full three-dimensional structure, information is invariably lost in the overlapping images of atoms at various heights. The technique of electron crystallography, in which information from several views of a crystal is combined, has been developed to obtain three-dimensional information on proteins. The resolution in images of proteins is severely limited by effects of radiation damage. In principle, atomic-resolution, 3D reconstructions should be obtainable from specimens that are resistant to damage. The most serious problem would appear to be in obtaining high-resolution images from areas that are thin enough that dynamical scattering effects can be ignored.
Digital image analysis: the quantitative measurement of nanometer features
Authors: Clancy John P.
Published: June 2020

An important goal of transmission electron microscopy (TEM) is the quantitative measurement of nanometer features. With digital analysis techniques, image features can be accurately measured in discrete pixels, but a scaling factor is needed to convert pixel units into real space units (e.g. angstroms in the case of an electron micrograph). For high-resolution TEM, fringe spacings are often used to obtain a scaling factor. In particular, the 111 cross-fringe pattern recorded at the 011 zone axis is the most common situation for electronic materials studies. However when variations in defocus and thickness are considered, the 011 high-resolution image (i.e. ∼ 2Å lattice) is quite complex. This complexity motivated a theoretical study which defines an optimum methodology for achieving scaling factors from digitized ultra-high resolution images (e.g. via a frame grabber). The results indicate that the preferred digital approach which has the least ambiguity and possibly the highest accuracy is achieved under 3-beam systematic imaging conditions.
Transmission Electron Microscopy studies of the vacancy ordering in YSI2-X thin films
Authors: Chen F.-R. , Lee T. L. , Chen L. J.
Published: June 2020

YSi2-x thin films were grown by depositing the yttrium metal thin films on (111)Si substrate followed by a rapid thermal annealing (RTA) at 450 to 1100°C. The x value of the YSi2-x films ranges from 0 to 0.3. The (0001) plane of the YSi2-x films have an ideal zero lattice mismatch relative to (111)Si surface lattice. The YSi2 has the hexagonal AlB2 crystal structure. The orientation relationship with Si was determined from the diffraction pattern shown in figure 1(a) to be and . The diffraction pattern in figure 1(a) was taken from a specimen annealed at 500°C for 15 second. As the annealing temperature was increased to 600°C, superlattice diffraction spots appear at position as seen in figure 1(b) which may be due to vacancy ordering in the YSi2-x films. The ordered vacancies in YSi2-x form a mesh in Si plane suggested by a LEED experiment.
High-resolution electron microscopy study on the interface of electrogalvanized coatings on sheet steel after heating
Authors: Lin Yuli , Chiou Wen-An , Meshii M.
Published: June 2020

Fe-Zn alloy coatings on sheet steel have been widely used by automobile industry due to their superior corrosion resistance and manufacturability. In order to investigate the interface structure between various phases in the Fe-Zn system and their crystallographic relations, steel sheets coated with electrogalvanized pure zinc were heat-treated at various temperatures and the resulting structures were examined in HREM with special attention to the formation of brittle Fe-Zn intermetallic phases.

Due to extreme difficulties in preparing cross-sectional TEM specimens from a thin Zn-based coating, little microstructural information is currently available for the interfacial region. A special technique was developed to overcome these difficulties in the present investigation. Instead of using the epoxy on the sandwiched specimens, as commonly adopted to prepare cross-sectional TEM specimens in electronic and photonic devices, 3mm of pure zinc was electrodeposited on top of the coating (15 μm) to be examined.
Thermally induced dislocation generation in Al/Al2O3 metal-matrix composites
Authors: Vecchio Kenneth S.
Published: June 2020

It has been well documented that when a large difference in the coefficients of thermal expansion (CTE) exist between the matrix and reinforcement in metal-matrix composites (MMCs) internal stresses can develop which are sufficiently high to generate dislocations at the reinforcement/matrix interface. Numerous observations have been made of this phenomenon via TEM which have shown a variety of different dislocation substructures and dislocation punching mechanisms. An important consequence of this phenomenon is that the metal matrix becomes strain hardened as the dislocation density increases, thereby reducing subsequent plastic flow of the matrix. One notable feature of the dislocation punching mechanism is that prismatic dislocation loops are commonly observed emanating from the interface. In two recent studies it was found that dislocations were not emitted immediately upon cooling, but rather at some lower critical temperature. A number of microstructural and processing parameters can affect the thermally-induced dislocation substructure such as: a) differences in CTEs, b) lattice frictional stress, c) vol.% particulate, d) particle/matrix interface morphology, e) quench temperatures (ΔT effect), and f) thermal-cycling (e.g. reheating and requenching).
Interfacial studies in Nb3Sn superconductors
Authors: Hall Ernest L. , Rumaner Lee E. , Benz Mark G.
Published: June 2020

The intermetallic compound Nb3Sn is a type-II superconductor of interest because it has high values of critical current density Jc in high magnetic fields. One method of forming this compound involves diffusion of Sn into Nb foil containing small amounts of Zr and O. In order to maintain high values of Jc, it is important to keep the grain size in the Nb3Sn as small as possible, since the grain boundaries act as flux-pinning sites. It has been known for many years that Zr and O were essential to grain size control in this process. In previous work, we have shown that (a) the Sn is transported to the Nb3Sn/Nb interface by liquid diffusion along grain boundaries; (b) the Zr and O form small ZrO2 particles in the Nb3Sn grains; and (c) many very small Nb3Sn grains nucleate from a single Nb grain at the reaction interface. In this paper we report the results of detailed studies of the Nb3Sn/Nb3Sn, Nb3Sn/Nb, and Nb3Sn/ZrO2 interfaces.
Characterization of carbides in M50NiL
Authors: Lin L. S. , Gumz K. P. , Karg A. V. , Law C. C.
Published: June 2020

Carbon and temperature effects on carbide formation in the carburized zone of M50NiL are of great importance because they can be used to control surface properties of bearings. A series of homogeneous alloys (with M50NiL as base composition) containing various levels of carbon in the range of 0.15% to 1.5% (in wt.%) and heat treated at temperatures between 650°C to 1100°C were selected for characterizations. Eleven samples were chosen for carbide characterization and chemical analysis and their identifications are listed in Table 1.

Five different carbides consisting of M6C, M2C, M7C3 and M23C6 were found in all eleven samples examined as shown in Table 1. M6C carbides (with least carbon) were found to be the major carbide in low carbon alloys (<0.3% C) and their amounts decreased as the carbon content increased. In sample C (0.3% C), most particles (95%) encountered were M6C carbide with a particle sizes range between 0.05 to 0.25 um. The M6C carbide are enriched in both Mo and Fe and have a fee structure with lattice parameter a=1.105 nm (Figure 1).
UHV-TEM imaging of surface reconstructions in B-doped Si<111>
Authors: Savage T. S. , Ai R. , Marks L. D.
Published: June 2020

A variety of techniques including LEED, STM and RHEED have been used to study surface reconstructions on the silicon <111> surface. Additionally, ultra high vacuum-transmission electron microscopy (UHV-TEM) has been used for a limited number of studies most notably on the 7x7 reconstructed surface. The limiting factor in these studies has been the availability of microscopes capable of in-situ sample preparation and imaging in a UHV environment. The Hitachi UHV-H9000 located at Northwestern University has recently been used to observe several surface reconstructions on a single crystal silicon <111> thin film. Transmission electron diffraction (TED) patterns were obtained for 7x7, and 5x1 surface reconstructions.
Use of TEM for characterization of reactions of MnO2 with Cr(III) and Al(III)
Authors: Fendorf M. , Fendorft S.E. , Sparkst D.L. , Gronsky R.
Published: June 2020

Metal sorption is an important aspect of surface environmental processes which dramatically affects environmental quality. Sorption phenomena are active in transport and oxidation/reduction reactions, bio-transformation, and in determining the ultimate fate of metals in surficial systems. Although oxide materials often only constitute a small fraction of the solid composition in surficial environments, their high surface area, reactivity, and coating abilities make them extremely influential in sorption. Surface precipitation provides a model for the sorption of hydrolizable metal ions at the solution/solid interface, and was successfully used to explain observed trends in the reaction of various metal ions on oxide surfaces (for example, the sorption of of Co(II) on MnO2, TiO2 and Al2O3).
Observations of surface structures and reaction products for materials exposed in space in low-earth orbit
Authors: Quinones Stella , Advani A.H. , Marquez Benito , Rivas Jesus , Miglionico C. , Murr L.E. , Fisher W.W. , Arrowood R.
Published: June 2020

A preliminary study of materials exposed in space in low-earth orbit for nearly six years (in the NASA Long-Duration Exposure Facility (LDEF)) has revealed a range of micrometeorite and microparticle impact craters and blisters of unknown origin on aluminum alloy 6061-T6 samples on the leading edge of the satellite. In addition these samples were covered with an enormous range of reaction products which included crystals and polycrystalline aggregates which originated in part from other reactions and atomic oxygen degradation taking place in systems proximate to the alloy samples.

A replication-type lift-off techniques was developed to remove reaction products (crystals and polycrystals, etc.) and debris from the specimen surfaces in order to isolate them from the background substrate without creating microchemical or microstructural artifacts. This technique culminates in extracted surface features resting on a carbon support film which is virtually “invisible” to observation by electron microscopy and non-dispersive x-ray analysis.
Advancing conventional High-Resolution Electron Microscopy
Authors: Gronsky Ronald
Published: June 2020

Due to the exceptional performance of most modern commercial transmission electron microscopes, the achievement of phase-contrast imaging resolution in the sub-2Å range is today a routine exercise, provided the samples are compliant. Nonetheless, there remains room for improvement, and the purpose of this manuscript is to highlight procedures that might be employed by the practicing microscopist for advancing conventional high resolution electron microscopy.
Observation of movement of atom images of 0.05-0.1 nm in 1/30 second
Authors: Hashimoto H. , Makita Y. , Yokota Y. , Aoba Y. , Miyoshi T. , Hashimot M.
Published: June 2020

The observation and recording of moving atoms in the crystals containing imperfections by TV system have been first carried out in 1978 and became popular, and commercialized after 1985. Since TV system can record the process of 1/30 seconds in one frame which consists of two interlacing frames of 1/60 seconds, the rapid movement of atoms of the order of 1/30 seconds can be detected. It was shown, by making the difference of two atomic structure images of gold crystals recorded in TV-tape at lOOkV, that the small displacement of atom column images as small as 1/10 of their diameters can be detected. In the present paper, the details of the three methods of subtraction and application to the images of Si crystals recorded in a video tape by using Berkeley AREM are shown.
Electron holography in materials science
Authors: Lichte Hannes , Voelkl Edgar
Published: June 2020

The object wave o(x,y) = a(x,y)exp(iφ(x,y)) at the exit face of the specimen is described by two real functions, i.e. amplitude a(x,y) and phase φ(x,y). In stead of o(x,y), however, in conventional transmission electron microscopy one records only the real intensity I(x,y) of the image wave b(x,y) loosing the image phase. In addition, referred to the object wave, b(x,y) is heavily distorted by the aberrations of the microscope giving rise to loss of resolution. Dealing with strong objects, a unique interpretation of the micrograph in terms of amplitude and phase of the object is not possible. According to Gabor, holography helps in that it records the image wave completely by both amplitude and phase. Subsequently, by means of a numerical reconstruction procedure, b(x,y) is deconvoluted from aberrations to retrieve o(x,y). Likewise, the Fourier spectrum of the object wave is at hand. Without the restrictions sketched above, the investigation of the object can be performed by different reconstruction procedures on one hologram. The holograms were taken by means of a Philips EM420-FEG with an electron biprism at 100 kV.
Divergent-beam holography with a 200keV FE TEM
Authors: Zhang Xiao , Joy David
Published: June 2020

A hologram, first described and named by Gabor (1949), permits a medium such as photographic film, which responds only to intensity, to store the complete amplitude and phase information which characterizes an electron wavefront. The hologram is formed by allowing some fraction of a coherent electron wave which has interacted with a specimen to interact again with original incident wave so as to generate an interference pattern. If the hologram is then itself illuminated by a coherent light source and optical system which mimic the original electron-optical system then a pair of images -one real and the other virtual -can be reconstructed and viewed. Because the hologram contains both the amplitude and the phase data of the wavefront, errors and distortions in either component due to aberrations in the objective lens can be corrected by optical manipulates before the image is reconstructed. With the advent of commercial field emission transmission electron microscopes capable of generating both high resolution images and highly coherent electron beams, these holographic techniques are now available as practical tools to improve TEM performance as well as to create new modes of images (Tonomura 1987).
Electron holography of frozen-hydrated biological specimens
Authors: Matsumoto T. , Osakabe N. , Endo J. , Matsuda T. , Tonomura A.
Published: June 2020

Electron holography has been applied to a variety of field, in which the reconstructed phase information was effectively used to elucidate many important natures of materials. Applications of electron holography to biological specimen, however, has not been developed yet. We report here an application of electron holography of frozen-hydrated biological specimen, which is observed by electron holography for the first time.

An electron microscope(Hitachi HU-12A) equipped with a 100-kV cold field emission gun was used for the experiment. Catalase crystals were embedded in amorphous ice by quick-freezing and the grids were transferred to the microscope using Gatan cryo transfer system. A specially designed low-dose imaging system for the microscope was devised and used to record holograms.
High-resolution Auger Electron Microscopy and spectroscopy of supported metal particles
Authors: Liu J. , Hembree G. G. , Spinnler G. E. , Venables J. A.
Published: June 2020

A detailed understanding of catalytic processes requires structural knowledge of the catalyst system. The surface properties of small metal particles which are highly dispersed on insulating supports must play a dominant role in determining this system's catalytic behavior. Therefore characterization of surface topography and composition of heterogeneous catalysts is important. Surface topography of the carrier materials can be obtained by high resolution secondary electron imaging (SEI) in a STEM. The small metal particles can also be located and their topographic relationship with the support morphology determined. However, an elementally specific signal such as the Auger electrons must be used to extract chemical information about the surface species. High resolution Auger electron spectroscopy (AES) and scanning Auger microscopy (SAM) have recently been incorporated into a UHV STEM. In this paper we report some results from the application of this instrumentation to the study of supported metal clusters.
Temperature effects on orientation-dependent Exelfs
Authors: Thiel Brad L. , Viney Christopher
Published: June 2020

Recently, investigations have begun to explore the effects of Mean-Square-Relative-Displacements (MSRD), or thermal damping, on the EXELFS oscillations above electron absorption edges. These types of analysis can be extended to include orientation effects in anisotropic crystal systems. Furthermore, as this technique is a direct probe of the electronic structure of a crystal, this information could be combined with the crystal symmetry and Cauchy relations to examine various physical properties. One such property is the elastic compliance quadric.

With the development of the parallel detection EELS spectrometer, EXELFS type studies have become practical. This makes accessible a large field of analysis, previously explored only by EXAFS. Thus, we are able to combine a wealth of experimental and data analysis algorithms from that technique with the high spatial resolution and crystallographic information afforded by the modern analytical TEM. We have developed computer simulation programs which demonstrate the feasibility of this hybrid analysis.
Quantitative light-element analysis using parallel EELS
Authors: Hunt J. A. , Strutt A. J. , Williams D. B.
Published: June 2020

Electron energy-loss spectrometry (EELS) is theoretically superior to x-ray emission spectrometry (XES) for light element microanalysis. The x-ray fluorescence yield decreases proportional to Z4, thus dramatically reducing characteristic x-ray production. However, the ionization cross section increases and so EELS becomes more efficient as Z decreases. Despite these advantages light element microanalysis using XES is often preferred to EELS. There are two major reasons why EELS is not more widespread. First, very thin specimens are needed to minimize plural scattering so quantification can proceed assuming single scattering. Secondly, many experimental variables make EELS difficult, particularly for microanalysts accustomed to the x-ray 'turn-key' approach to quantification. The former problem is being overcome with multiple least-squares (MLS) fitting deconvolution routines, while the latter has largely been solved by the development of parallel EELS (PEELS) and powerful analysis software. In this paper we show the quality of data currently available using PEELS.
Application of electron energy loss spectroscopy to microanalysis of irradiated stainless steels
Authors: Kenik E. A. , Bentley J. , Evans N. D.
Published: June 2020

Energy dispersive X-ray spectroscopy (EDXS) has limited application to microanalysis of radioactive materials because of degraded detector performance and the “intrinsic” spectrum associated with the radioactive decay. Electron energy loss spectroscopy (EELS) is not affected by specimen radioactivity and also offers the possibility of improved spatial resolution. Measurements of radiation-induced segregation (RIS) in irradiated stainless steels have been made by both techniques. Analytical electron microscopy was performed at 100 kV in a Philips EM400T/FEG, equipped with an EDAX 9100/70 EDXS system and a Gatan 666 parallel detection EELS (PEELS). Microanalysis was performed in the STEM mode (<2-nm-diam probe with >0.5 nA) with the same acquisition time (50 s) used for both techniques.

Initial measurements were performed on an ion-irradiated modified type 316 stainless steel (designated LS1A), which had moderate-width (∼20 nm) RIS profiles at grain boundaries. Profiles measured by EDXS and PEELS match well and show chromium depletion and nickel enrichment (Fig. 1).
Micromagnetics of longitudinal recording media
Authors: Alexopoulos P.S.
Published: June 2020

Future needs in high density magnetic storage devices require increases both in linear and track densities. The latest 1 Gigabit per square inch areal density for longitudinal media demonstrated by IBM has reduced the bit size to dimensions comparable to the characteristic micromagnetic length scales of todays media. Improvement or extension of the current recording limits requires detailed knowledge of micromagnetics and their manipulation or tailoring through the microstructure of the utilized magnetic thin films. There is a number of ways that these parameters can be controlled through the microstructure of the thin films including: chemical alloying, use of nucleating underlayers, and deposition parameters. Our investigation of written transitions recorded on a series of cobalt based alloys using Lorentz microscopy showed that the domain wall structures observed in the transition zones are very complex (Figure 1). The transition zones contain not only zig-zags shape 180° walls but also vortex structures and intermediate states between the two.
A high-resolution transmission electron microscopy investigation of the interfacial structure of CoNiCr/Cr bi-layer magnetic thin films
Authors: Wong B. Y. , Laughlin D. E.
Published: June 2020

The use of performance enhancement underlayers is a common practice in production of magnetic recording media. In the case of Co-based alloy deposited on chromium underlayers, the enhancement in the in-plane coercivity is phenomenal. Conventional and High Resolution TEM are powerful tools in the investigations of structure of these films because of the very fine grain size of the films. Previous microdiffraction studies on these bi-layer films have revealed the apparent grain to grain orientation relationship (O.R.) between individual grains in the two layers in the plane view sections of these specimens. Since the underlayer exerts such a great influence on the structure and properties of the overlayer, it is of great importance to study the interfacial structure of these bi-layer films. The lattice matching across the interface and the interfacial defects which formed could very well provide explanation(s) to the enhancement in the in-plane coercivity.
The depth sensitivity of Type II magnetic contrast
Authors: Ferrier R.P. , McVitie S.
Published: June 2020

Type II magnetic contrast arises from the change in the effective electron backscattering coefficient due to interaction of the scattered electrons and the magnetic induction present within a ferromagnetic sample; both domain and "domain wall" contrast are observable depending on the relative geometry of the beam, the specimen and the detector (for a review see Tsuno). A major problem with Type II contrast is that it is very weak and can be swamped easily by even relatively low topographic or atomic number contrast. For studies of the domain wall dynamics in thin film recording heads Wells and Savoy overcame this problem by driving the head with an a.c. voltage and detecting, via a lock-in amplifier, the synchronous part of the backscattered signal.
Magnetic force microscopy
Authors: Grütter P. , Rugar D. , Mamin H.-J. , Albrecht T.R.
Published: June 2020

The aim of this talk is to give a short introduction to the technique of magnetic force microscopy (MFM), review recent advances in instrumentation and present measurement on various magnetic materials.

MFM [1, 2] is a non-destructive method which allows the imaging of magnetic structures with little or no sample preparation on a 50-100 nm scale. The central component of every MFM is a sharp magnetic tip mounted on a flexible cantilever. The interaction of the magnetic tip with a sample stray field leads to a change of both cantilever deflection and resonant frequency. These changes are measured with a sensitive displacement probe, eg. an interferometer. Images are generated by raster scanning the sample relative to the tip and recording the tip-sample interaction as a function of position.
Novel magneto-optical recording materials: Bi-substituted garnet films
Authors: Suzuki Takao , Nuri Hossein
Published: June 2020

For future high density magneto-optical recording materials, a Bi-substituted garnet film ((BiDy)3(FeGa)5O12) is an attractive candidate since it has strong magneto-optic effect at short wavelengths less than 600 nm. The signal in read back performance at 500 nm using a garnet film can be an order of magnitude higher than a current rare earth-transition metal amorphous film. However, the granularity and surface roughness of such crystalline garnet films are the key to control for minimizing media noise.

We have demonstrated a new technique to fabricate a garnet film which has much smaller grain size and smoother surfaces than those annealed in a conventional oven. This method employs a high ramp-up rate annealing (Γ = 50 ~ 100 C/s) in nitrogen atmosphere. Fig.1 shows a typical microstruture of a Bi-susbtituted garnet film deposited by r.f. sputtering and then subsequently crystallized by a rapid thermal annealing technique at Γ = 50 C/s at 650 °C for 2 min. The structure is a single phase of garnet, and a grain size is about 300A.
Two-dimensional omega energy-filtered CBED on the new Zeiss EM912
Authors: Mayer J. , Spence J.C.H. , Mobus G.
Published: June 2020

The Zeiss EM912 is a new digital, side-entry, 120 kV TEM/STEM for materials science, with omega magnetic imaging energy filter. Smallest probe is 1.6 nm. We have evaluated the 912 for quantitative CBED because we believe that the zero-loss filtered diffraction pattern is the most accurately quantifiable signal of any on a modern analytical TEM/STEM instrument. A double tilt holder and W filament were used. The magnetic filter allows energy-filtered images or diffraction patterns to be recorded without scanning using efficient parallel (area) detection. Comparisons with FEG STEM instruments depend on field of view - for a 103X103 pixel image, recording time with the Omega filter using LaB6 is 1000 times less than that of a STEM with a FEG (103 times brighter) for the same dose. For accurate measurement of structure-factor amplitudes and phases, elastic energy-filtered data must be used. This Bloch-wave refinement method has now been automated using "Simplex" multivariate analysis.
Diffraction theory of phonon-scattered electrons
Authors: Wang Z. L.
Published: June 2020

Electron-phonon interactions are inelastic scattering processes in high-energy electron diffraction, and are responsible for thermal diffuse scattering (TDS). The atomic thermal vibrations introduce a small time-dependent perturbation to the crystal potential

(1)

where is the displacement of the atom (at position within the hth unit cell (position R(h)) from its equilibrium position,

(2)
TEM characterization of silicon epitaxial layer grown on Si-TaS2, eutectic composites
Authors: Sung C.M. , Levinson M. , Tabasky M. , Ostreicher K. , Ditchek B.M.
Published: June 2020

Directionally solidified Si/TaSi2eutectic composites for the development of electronic devices (e.g. photodiodes and field-emission cathodes) were made using a Czochralski growth technique. High quality epitaxial growth of silicon on the eutectic composite substrates requires a clean silicon substrate surface prior to the growth process. Hence a preepitaxial surface cleaning step is highly desirable. The purpose of this paper is to investigate the effect of surface cleaning methods on the epilayer/substrate interface and the characterization of silicon epilayers grown on Si/TaSi2substrates by TEM.

Wafers were cut normal to the <111> growth axis of the silicon matrix from an approximately 1 cm diameter Si/TaSi2composite boule. Four pre-treatments were employed to remove native oxide and other contaminants: 1) No treatment, 2) HF only; 3) HC1 only; and 4) both HF and HCl. The cross-sectional specimens for TEM study were prepared by cutting the bulk sample into sheets perpendicular to the TaSi2fiber axes. The material was then prepared in the usual manner to produce samples having a thickness of 10μm. The final step was ion milling in Ar+until breakthrough occurred. The TEM samples were then analyzed at 120 keV using the Philips EM400T.
A SIMS-TEM study of fluorine implants and anneals into silicon and polysilicon
Authors: Kaushik Vidya S. , Hance Robert L. , Tseng Hsing-H. , Tobin Philip J.
Published: June 2020

The behavior of fluorine in silicon is important for VLSI applications. The presence of fluorine can lead to improved gate oxide interface reliability and to enhanced boron diffusion in BF2 implanted devices. We have therefore studied the diffusion behavior of fluorine in silicon and polysilicon using coupled SIMS and TEM investigations on samples implanted with fluorine alone.

Fluorine was implanted into a) (100) silicon and b) polysilicon layers to a dose of 1 x 1016/cm2 at 60 keV at room temperature. The polysilicon layers were grown by LPCVD at 635°C, resulting in small grained columnar polysilicon. The polysilicon layers had a 50 nm grown oxide layer between the polysilicon layer and the (100) silicon substrate. After the fluorine implants, the wafers were subjected to annealing at 750-950°C for 30 minutes. All the wafers were capped with a 13 nm silicon dioxide layer at the wafer surface prior to the ion implantation. SIMS analysis was performed on a Cameca IMS-3F spectrometer with 10 keV O2+ ions. XTEM images were obtained on a JEOL 2000 FXII operated at 200 keV with the electron beam parallel to the <110> silicon zone axis.
Nanoanalysis of impurity precipitation on grain boundaries in polysilicon
Authors: Kim M.J. , Carpenter R.W. , Schroder D.K. , Wohlgemuth J.H.
Published: June 2020

Polycrystalline silicon (polysilicon) has been the subject of extensive studies in recent years due to its wide applications in microelectronics and solar cells, see for example references. In most cases of interest impurities segregated to the grain boundaries strongly modify the electronic properties of this material. Understanding the behavior of impurities in polysilicon requires a detailed knowledge of their distribution, phase and thermodynamical stability. In the present study, the structure and chemistry of grain boundaries in polysilicon were characterized by HREM and very high spatial resolution FEG/AEM.

The specimen materials are Solarex cast polysilicon used for solar cells, which are manufactured under a proprietary method called the ubiquitous crystallization process. The samples for TEM observations were cut from the ingot perpendicular to its growth direction and then thinned to electron transparency by mechanical polishing and ion milling. HREM was performed at 200kV in an ISI-002B. Microanalysis was done using a Philips 400ST/FEG microscope coupled to a Gatan parallel-detection electron energy loss spectrometer, at 100kV. A liquid nitrogen cooled specimen holder was used for nanoprobe experiments to minimize specimen contamination and local specimen heating.