bluuebunny/crossref_metadata_2025 huggingface dataset:
Morphological and Chemical Characterization of a Mechanically Alloyed Rubber Toughened PMMA With X-Ray Spectromicroscopy
Authors: Smith A P , Ade H , Spontak R J , Koch C C
Published: July 2020

Rubber toughening was first developed about seventy years ago as a method of increasing the impact resistance of brittle glassy polymers. Since that time, a wide variety of techniques have been developed to produce discrete dispersions of rubber within a glassy polymer matrix. We are exploring a new route to rubber-toughen polymer through the non-equilibrium process of mechanical alloying (high-energy ball milling). Here we have blended poly(methyl methacrylate) (PMMA) with polyisoprene (PI) (see the insets in Fig. 1 for chemical structures) and have characterized the resultant blends with Scanning Transmission X-ray Microscopy (STXM) in order to obtain chemical, as well as morphological, information about the blends.

The STXM technique utilizes tuneable soft x-rays that are focused with a diffraction zoneplate to a microprobe of 45 nm full width at half maximum. Thin sections of the sample are placed at the microprobe and the transmitted photon intensity is measured.
EDS from then Till Now—A Chronology of Innovation
Authors: Friel John J
Published: July 2020

Since its introduction in 1968 on both the EPMA and SEM, the energy-dispersive spectrometer has become widely used from research laboratories to production testing. It has become the mainstay for microanalysis in many scientific disciplines. A discussion of energy-dispersive spectrometry (EDS) logically divides into two lines of development: X-ray detector/hardware and X-ray analyzer/software. Of the several types of EDS detectors, only Si(Li) and intrinsic germanium detectors (IG) will be covered in this review, as they are the most common on electron microscopes.

The 1960s— The use of a solid state EDS detector on an EPMA was first described by Fitzgerald, et al. in 1968.1 They realized at the time that the high collection efficiency of about 80% permitted analysis at lower beam current for the same counting statistics and electron dose on the specimen. The first installation of a Si(Li) detector on an SEM came later the same year.
SI(LI) and Hpg Detectors: Recent Measurements
Authors: Sareen R A , Nashashibi T
Published: July 2020

Small Si (Si(Li), Intrinsic Si, PEN diodes) and Ge (HPG) planar detectors are used for measuring the energy and intensity of X-rays at low energies (below 100 keV). Applications include energy dispersive microanalysis in the electron microscope and x-ray fluorescence in tube excited systems. They are also finding increasing use on synchrotron beam lines. Both types of detector have unique and special properties and there is a wealth of information in the literature1 describing their principles of operation including their spectral characteristics.

For example, the superior resolution (110 eV compared to 130 eV (FWHM) at 5.9 keV) obtained with 10 mm2 HPG detectors is a consequence of Ge's smaller band gap (0.7 eV compared to 1.1 eV eV for Si). This leads directly to a lower value for the activation energy (2.9 eV compared to 3.81 eV at 77K). Both materials have very similar Fano factors (approximately 0.11).
The Impact of EDS In Materials Science Microanalysis
Authors: Williams D B
Published: July 2020

Since its invention in 1968, the EDS has played an essential role in X-ray analysis of materials, at the micrometer level, in the electron probe microanalyzer (EPMA). In the EPMA, the characteristic X-ray intensity from bulk specimens is sufficient that, despite its very small collection angle, the wavelength dispersive spectrometer (WDS) can also be used. Given the excellent energy resolution of the WDS it has often been the spectrometer of choice for bulk quantitative X-ray microanalysis. Therefore, the most important role of the EDS has been in X-ray microanalysis of thin specimens in the analytical electron microscope (AEM) because, in an AEM, the limited confines of the stage mean that EDS is the only viable spectrometer. Since the pioneering work of Cliff and Lorimer in the 1970s, EDS has been the method by which all high spatial resolution X-ray microanalysis of thin foils has been performed.
The Use of Energy Dispersive X-Ray Microanalysis in the Geological Sciences: 30 Years of Heavy and Creative Application
Authors: Armstrong John T
Published: July 2020

Considering the heavy use by the geological community that followed, it is not surprising that first two authors of the introductory paper in Science on the energy dispersive x-ray spectrometer applied their x-ray microanalysis skills predominantly in the geological sciences. The energy dispersive spectrometer became first commercially available at an ideal time for the geological community. During the 1960’s, mineralogists and petrographers like K. Keil, J.V.P. Long, J.C. Rucklidge, J.V. Smith, A. Albee, and A. Chodos demonstrated that electron microprobe analysis with wavelength dispersive spectrometers could provide accurate in-situ analysis of portions of individual mineral grains on a scale not readily obtainable by other techniques (e.g., 2-3 and cited refs.). The electron microprobe enabled analysis of features observed by reflected- and transmitted-light polarized optical microscopy (prime tools of the mineralogist and petrographer) and was beginning to be used routinely for the study of meteorites and terrestrial rocks and even more exotic types of specimens, like individual microparticles from sediment and airborne particulate samples.
Energy Dispersive Spectrometry in the AEM
Authors: Michael J R
Published: July 2020

Energy-dispersive x-ray spectrometry (EDS) with a SiLi detector has become a standard technique in the analytical electron microscope (AEM). There have been many difficulties to overcome involving both the interfacing of the spectrometer to the microscope and in developing robust techniques for quantitative analysis of thin specimens. The AEM is a difficult environment for EDS due to the high accelerating voltages (100-400 kV) typically used and due to constraints on detector placement relative to the specimen as a result of the confined space within the specimen region of the AEM. The first published account of the installation of SiLi EDS on a transmission electron microscope (TEM) occurred in 1969. In this paper and subsequent publications, these authors described many of the difficulties that still haunt EDS in the AEM.

The initial attempts at interfacing EDS to a TEM column demonstrated that the. specimen stage of a TEM was not ideal for this purpose.
Low Beam Energies for EDS Chemical Microanalysis in the SEM (LVEDS)
Authors: Boyes E D
Published: July 2020

Microanalysis data depe nd strongly on the electron beam energy used in the S E M and the effects are more pronou nced with bulk samples than with thin sections. The situation can be used to advantage but there are also significant problems. The data and any quantitative corrections can be quite different at different beam energies. Th e spectra look different and this can be both helpful and confusing, with low ene rgy x-ra y lines generally more prominent at lower voltages. S p ec tra at several different voltages are particularly informative, both for quantitative analysis and to deco nvo lute three dimensional geometries. There may be no single perfect voltage for an analysis.
Computer Simulation Applied to WD Analysis
Authors: Reed S JB , Buckley A
Published: July 2020

The efficiency and reliability of WD analysis can be enhanced substantially by means of computer simulation carried out before embarking on the actual analysis, thereby eliminating the need for a time-wasting ‘trial and error’ process and preventing errors in quantitative analysis due to line overlaps etc. which otherwise might be undetected. By displaying on-screen the combined spectra of elements known or expected to be present in a given sample, overlaps can be studied in detail, which may indicate the preferability of using an alternative analytical peak (e.g. L(Lβ1 instead of Lα1). The selection of optimum background positions with minimal overlap from neighbouring elements is also facilitated. These choices can be made much more rapidly and reliably than by depending on wavelength tables, while also saving the considerable instrument time required to carry out wavelength scans for each new type of sample.
Electron Probe Evaluation of Heterogeneity in the Certification of NIST Standard Reference Materials for Microanalysis
Authors: Marinenko R B , Leigh S
Published: July 2020

The certification process for a microanalysis standard can be quite lengthy. In addition to certifying the reference material for composition, the extent of heterogeneity between specimens and within specimens must be determined. NIST (or formerly, NBS) 260 Special Publications have been used in the past to describe procedures used for individual SRM certifications. Some of these publications describe in detail how the extent of microheterogeneity (or, microhomogeneity) as well as the specimen to specimen heterogeneity can be determined. The intent here is to describe a general statistical approach used at NIST to determine and report the extent of heterogeneity. This approach can be readily used by other laboratories either for certification or for evaluation of standards.

When evaluating a material for use as a standard, there are several physical characteristics which must be satisfied. The material must be robust under the electron beam at the voltages and currents to which it will be subjected in its proposed use. When mounted and polished, it should be stable on exposure to the atmosphere. However, if the material will not be mounted and polished in use, it should be in the same physical form as the final certified standard material.
A Microprobe Study to Differentiate Bulk Chemical Data by Neutron Activation Analysis on Guatemalan Pottery
Authors: Ross L , Cogswell J , Neff H
Published: July 2020

Bulk chemical characterizaton with techniques such as neutron activation analysis (NAA) has been used for many years to identify sources of archaeological artifacts by comparing bulk chemical profiles of archaeological artifacts to profiles determined for samples of raw material for source identification. The chemical approach to determining the provenance of archaeological pottery is complicated by the paste preparation activities of potters and by post-depositional processes. In a ceramic provenance investigation, the investigator typically identifies a series of relatively homogeneous subgroups, which most often are assumed to represent geographically restricted raw material sources. Although the source-specific interpretation is often the most parsimonious explanation of compositional patterning, it is really only the first of several competing hypotheses which, singly or in combination, might account for patterns of similarity and difference in a compositional data set. In this case, two white firing pottery types (SAWH and Ivory) made during the Late and Terminal Formative periods (300 B.C. - 200 A.D.) in southeastern Mesoamerica (Guatemala) were found to be chemically distinct.
Image Formation With Upper and Lower Secondary Electron Detectors in the Low Voltage Field-Emission SEM
Authors: Liu J
Published: July 2020

High-resolution secondary electron (SE) imaging was first demonstrated at 100 kV in the STEM a decade ago. High-resolution SE imaging is now routinely obtainable in field-emission SEMs. Although nanometer-scale surface features can be examined at low incident beam voltages we still do not fully understand the factors that affect the contrast of low voltage SE images. At high incident beam voltages, SE1 (SEs generated by the incident probe) and SE2 (SEs generated by backscattered electrons at the sample surface) can be spatially separated. SE1 carries high-resolution detail while SE2 contributes to background. At low incident beam voltages, however, the interaction volume of the incident electrons shrinks rapidly with decreasing incident beam voltage. Thus, both the SE1 and SE2 signals carry high-resolution information. At low incident beam voltages, SE3 (SEs generated by backscattered electrons impinging on the sample chamber, pole pieces and etc.) also carries high-resolution detail and contributes significantly to the collected signal, especially for high atomic number materials and at short working distances.
Multivariate Statistical Analysis of Low-voltage EDS Spectrum Images
Authors: Anderson Ian M
Published: July 2020

Whereas energy-dispersive X-ray spectrometry (EDS) has been used for compositional analysis in the scanning electron microscope (SEM) for 30 years, the benefits of using low (<5 kV) operating voltages for such analyses have been explored only during the last few years. This paper couples low-voltage EDS with two other emerging areas of characterization: spectrum imaging and multivariate statistical analysis (MSA). The specimen analyzed for this study was a finished Intel Pentium processor, with the polyimide protective coating stripped o ff to expose the final active layers. Data acquisition was performed with a Philips XL30-FEG SEM operated at 2 kV and equipped with an Oxford super-ATW detector and XP3 pulse processor. The specimen was normal to the electron beam and the take-off angle for acquisition was 35°. The microscope was operated with a 150 μm diameter final aperture at spot size 6, which yielded an X-ray count rate of ∼1000 s-1.
Beam Size in the Environmental SEM: a Comparison of Model and Experimental Data
Authors: Wight S A
Published: July 2020

Knowledge of the magnitude of the scattered electron skirt in the environmental scanning electron microscope (ESEM) or low vacuum scanning electron microscope (LVSEM) is important to the understanding of the analytical spatial resolution of energy dispersive spectrometry (EDS). The extent of beam scattering is a function of the distance from the final aperture to the specimen, composition of the gas present, chamber pressure, accelerating voltage, and beam current. This work compares model predictions of electron scattering to experimental measurements of electron scattering. Several of the popular Monte Carlo programs written for electron-solid interactions were not designed for low vacuum conditions. Joy has developed a model that takes into account the electron scattering which takes place in the chamber before interacting with the specimen; thus it is useful for LVSEM conditions. That model is incorporated in Electron Flight Simulator - E (Small World, Vienna VA)1 and is used in this work.
Topographic Comparison of G-Wire DNA Imaged by Hydration Scanning Tunneling and Atomic Force Microscopy as a Function of Humidity
Authors: Janigian D , Morales E , Muir T , Garcia B , Vesenka J
Published: July 2020

The tendency of poly-G oligonucleotides to undergo self-assembly into helical nucleic acid tetramers have been termed G-quartets. Also known as G-wires, these structures retain their crystallographic determined dimensions better than duplex DNA when imaged with the atomic force microscope (AFM). Relative humidity has been known to affect both the resolution and measured height DNA strands on mica. The results below aim to develop a model that can be used to define the mechanical properties of G-wires by scanning probe microscopy investigations. G-wires were examined under a wide range of relative humidity to determine their tolerance to shear forces under the AFM, and to establish imaging conditions for hydration scanning tunneling microscopy (HSTM).

The relative humidity dependence of G-wires were taken with 125 μm long, 20 μm wide silicon nitride cantilevers in contact AFM mode (spring constant ∼ 0.4 N/m) (Fig. 1).
Using a Moderate Vacuum, Hot/Cryo-Stage Equipped AFM for In-Situ Observation of α-Phase Growth In 60SN40PB Hypoeutectic Solder
Authors: Leonard D N , Russell PE
Published: July 2020

Atomic force microscopy (AFM) was introduced in 1984, and proved to be more versatile than scanning tunneling microscopy (STM) due to the AFM's capabilities to scan non-conductive samples under atmospheric conditions and achieve atomic resolution. Ultra high vacuum (UHV) AFM has been used in surface science applications when control of oxidation and corrosion of a sample's surface are required. Expensive equipment and time consuming sample exchanges are two drawbacks of the UHV AFM system that limit its use. Until recently, no hot/cryo-stage, moderate vacuum, controlled gas environment AFM was commonly available.

We have demonstrated that phase transformations are easily observable in metal alloys and polymers with the use of a moderate vacuum AFM that has in-situ heating/cooling capabilities and quick (within minutes) sample exchange times. This talk will describe the results of experiments involving a wide range of samples designed to make use of the full capabilities of a hot/cryo-stage, controlled gas environment AFM.
Diamond Indenter Shaping Using Focused Ion Beam
Authors: Phillips JR , Jarausch KF , Stark TJ , Houston JE , Griffis DP , Russell PE
Published: July 2020

Nanoindentation is becoming an increasingly important tool for the characterization of the mechanical properties of materials on the nanometer scale. The mechanical response of a material is measured by recording the force acting between an indenter and the material while displacing the indenter into the material. The shape of the recorded load displacement curves is not only dependent on the mechanical properties of the material, but also strongly dependent on indenter geometry. To minimize difficulties in the extraction of quantitative material mechanical property information from the force curve, indenter geometry must be controlled and characterized on the same scale as the indentation, i.e. on the nanometer scale. Diamond, the hardest naturally occurring material, is an obvious choice as the indenter material. Conventional lapping techniques4 do not provide sufficient control to produce indenter geometries of the shapes and to the precision required for optimal nanoindentation measurements.
Nanomanipulation for Material Properties, Substrate Interactions and Devices
Authors: Superfine R , Falvo M R , Clary G J , Paulson S , Taylor R M , Chi V , Brooks F P , Washburn S
Published: July 2020

In many cases in experimental science, it is true that the instrument interface becomes a limiting factor in the efficacy of carrying out unusual experiments, or prevents the complete understanding of the acquired data. We are developing an advanced interface for Scanning Probe Microscopy (SPM) which allows intuitive rendering of datasets and natural instrument control, all in real-time. The interface, called the nanoManipulator, combines a high performance graphics engine for real-time data rendering with a haptic interface which places the human operator directly into the “feedback loop” that controls surface manipulations. In practice, the user holds a stylus in hand. By moving the stylus laterally, the user directs the movement of the SPM tip across the sample. The haptic interface enables the user to “feel” the surface by forcing the stylus to move up and down in response to the surface topography.
Electron Scattering In Diamond as a Function of Thickness
Authors: Bell David C
Published: July 2020

Background

The electron energy-loss spectrum of a single crystal diamond wedge has been examined, with particular reference to the excitation of plasmon oscillations in the bulk of a diamond crystal. The electron energy-loss spectrum has been previously studied [1], and in particular the ‘low-lo ss’ region of the spectrum shows a number of important features, Fig. 1. The main feature in the energy-loss spectrum is a peak at ∼ 33 eV which corresponds to a plasma resonance of valence electrons. Diamond has 4 valence electrons which yields a value of Ep = 31.0 eV. The upward shift in the resonance energy to 33 eV is caused by single-electron excitation at lower energy-loss values. An important feature is the “bump” at about 23 eV, which has been shown to be an interband transition [2].
Absorption Potential for Dynamic Electron Diffraction - A Revisit
Authors: Wang ZL , Zhang Chen
Published: July 2020

Quantitative analysis of structural information provided by transmission electron diffraction and imaging strongly relies on computer simulations. An important quantity in dynamic calculation is the “absorption” potential. The absorption here actually means that the electron is not absorbed by the specimen rather it is scattered out of the elastic state (or Bragg peaks) due to energy-loss and momentum transfer, resulting in a decrease in the intensity of the elastic wave. This is the effect of inelastic scattering (or diffuse scattering) on the Bragg reflected waves [1]. Almost all of the model calculations for the absorption potential have been based on the approximation o riginally introduced by Y o sh ioka, in which the Green's function is approximated by its form in free-space. Thus, the absorption potential is simplified into a non-local function that depends only on the nature of the inelastic scattering.
Application of Synchrotron Radiation to Analysis of Both Contamination and Structure of Silicon Surfaces and Interfaces
Authors: Pianetta P , Brennan S
Published: July 2020

Synchrotron Radiation has become an important tool for the analysis of silicon surfaces in both fundamental and applied problems with techniques ranging from x-ray scattering to fluorescence. Applications that have been studied include the analysis of ultra-low levels of impurities on silicon wafer surfaces using the total external x-ray fluorescence technique (TXRF), measurement of silicon wafer surface roughness using crystal truncation rod scattering, measurement of the stress and defects associated with isolation trenches used in the fabrication of integrated circuits, and the study of transient enhanced diffusion in implanted silicon using x-ray diffuse scattering.

As the dimensions of integrated circuits become smaller and smaller, the thickness of the gate oxide is being reduced to a level where it has become necessary to control the process to virtually atomic levels. With oxide thicknesses less than 100 Angstroms, surface impurities can have deleterious affects on the oxide properties.
Mephisto: A Novel Synchrotron Imaging Photoelectron Spectromicroscope
Authors: Stasio Gelsomina De
Published: July 2020

We discuss the scheme and test performances of the recently commissioned MEPHISTO system in its final configuration. The tests show that the improvements in the electron optics system with respect to other instruments in the same class made it possible to reach lateral resolutions in the 50 nm range. They also demonstrate rather good spectromicroscopy and spectroscopy performances, reliability and flexibility of operation.

This instrument belongs to the class of the electron-imaging systems, like the PEEM (PhotoElectron Emission Microscope) [1] and the X-PEEM (X-ray PhotoElectron Emission Microscope) Microscope [2-5], Our new instrument, called MEPHISTO from the French acronym “Microscope a Emission de Photo électrons par Illumination Synchrotronique de type Onduleur” (Photoelectron Emission Microscope by Synchrotron Undulator Illumination) shares the good characteristics of the instruments of its class: real-time chemical imaging, fast taking of local x-ray absorption spectra, high spatial resolution, large dynamic range, flexibility and user-friendliness.
Comparing Elemental Sensitivities Obtained With an Aperture and a Monolithic Polycapillary Optic Using a Commercial Micro-X-Ray Fluorescence (MXRF) Instrument
Authors: Worley C G , Colletti L P , Havrilla G J
Published: July 2020

Recent MXRF reports have demonstrated marked x-ray flux enhancements over traditional aperturecollimating systems when using a total reflection capillary optic. In the present work, several standard reference materials (SRMs) were examined with a Kevex Omicron MXRF system to compare the elemental sensitivities achieved with an aperture x-ray guide to those obtained with a monolithic polycapillary optic (X-ray Optical Systems). This study is relevant to the MXRF community using commercial aperture-based instruments where trace elemental concentrations in a sample sometimes mandate the need for a higher primary x-ray dose, but the flexibility of incorporating various sized apertures for other samples is still maintained.

By scanning the x-ray beam over a nickel/gold knife edge, the capillary focal spot diameter at the time of this work was determined to be ∼400 μm, while a 300 μm aperture provided a beam size of ∼550 μm due to beam divergence past the aperture.
Development of a Side Entry High Tilt Cryotransfer Stage for Tomographic Applications
Authors: Armbruster BL , Zolkowski R , Swann PR
Published: July 2020

Three-dimensional electron microscopic imaging, or electron tomography, involves the reconstruction of individual objects from projection data collected over a large range of specimen tilts. Practical limitations of tomography are set by the range of specimen tilt available to generate projection data. In terms of tilt range, current data sets typically cover a range of up to +/-700° of tilt.

When used for applications requiring high tilt such as tomography, problems with specimen holder designs which use circular 3mm diameter grids include restricted field of view created by the standard mesh pattern of commercially available specimen grids. The standard square or hexagonally patterned support grids provide minimal area between grid bars to view a sample at high tilt. The width of the specimen clamping device and holder tip blade also limit the useable grid area to the center of the specimen when the holder is at high tilt positions.
Development of High Resolution FE-SEM (8"FE-SEM) For 8-Inches wafer inspection
Authors: Ohara K , Nielsen C , Saito M
Published: July 2020

Semiconductor production using 8-inches wafers seems to be widely carried out in semiconductor factories. Many FE-SEMs are coming to be used for their particle/defect inspection. As semiconductor processing turns precise, the need of a high resolution FE-SEM has been rising all the more.

Now, JEOL announces a high resolution FE-SEM (8"FE-SEM) for 8-inches wafer inspection, which takes over the strong point of the semi-in-lens field emission scanning electron microscope (FE-SEM) JSM-6340F which has been getting expensive evaluation with its high resolution performance. The 8"FE-SEM possesses a resolution of 3.0nm at lkV of its acceleration voltage and 1.2nm at 15kV, as its semi-in-lens type object lens makes it possible to minimize the aberration.

High resolution observation and inclined wafer observation can be selected properly by changing the wafer holder, as such a holder exchange system has been usually used for transmission electron microscopes.
Quantitative Immunocytochemistry of Proteins Using 2- Photon Microscopy and Digital Image Analysis.
Authors: Wan H , Soeller C , Garrod DR , Robinson C , Cannell MB
Published: July 2020

The two photon microscope provides optical sectioning of fluorescent specimens with a resolution comparable to that obtained in confocal microscopy (see refs 2,3). However, the excited volume in 2-photon microscopy is limited to the focal volume (unlike conventional fluorescence microscopy where excitation occurs throughout the specimen). This means that photodamage is limited to the plane of section being examined. Thus, the light emitted from each point in the specimen depends on the amount of fluorochrome present without the problem of prior illumination (of other planes within the specimen) reducing the photon yield so a better signal to noise ratio can be obtained when examination of multiple image planes is needed. Since 2-photon excitation spectra are wide and chromatic aberration is eliminated (because the emitted light does not have to be focused on a pinhole), it is possible to excite several fluorochromes simultaneously and map their positions with high accuracy.
Tomographic Reconstruction of the Hair Cell Ribbon Synapse
Authors: Lenzi David , Runyeon Jonathan W , Crum John , Ellisman Mark H , Roberts William M
Published: July 2020

Hair cells, the mechanotransducers of the inner ears and lateral lines of vertebrates offer an excellent preparation for the study of presynaptic mechanisms at fast chemical synapses. They offer the compact, almost cylindrical shape of an epithelial cell without entangling dendrites and axons, and make afferent synapses directly from the cell body. The biology of hair cells demands an unusually high performance of the output synapse, requiring continuous, and very quickly modulated transmitter exocytosis. Release follows the small receptor potential generated by the transduction apparatus; more transmitter is released upon depolarization, less after hyperpolarization. In some hair cells, transmission can phase-lock to kilohertz stimulus frequencies, preserving temporal information across the synapse.

We have exploited the synaptic terminal-like features of these cells to explore both the physiology and ultrastructure of the machinery underlying neurotransmitter release.
Correlated 3D Light and Electron Microscopy of Large, Complex Structures: Analysis of Transverse Tubules in Heart Failure
Authors: Martone Maryann E , Thor Andrea , Young Stephen J , Ellisman. Mark H
Published: July 2020

Light microscopic imaging has experienced a renaissance in the past decade or so, as new techniques for high resolution 3D light microscopy have become readily available. Light microscopic (LM) analysis of cellular details is desirable in many cases because of the flexibility of staining protocols, the ease of specimen preparation and the relatively large sample size that can be obtained compared to electron microscopic (EM) analysis. Despite these advantages, many light microscopic investigations require additional analysis at the electron microscopic level to resolve fine structural features.

High voltage electron microscopy allows the use of relatively thick sections compared to conventional EM and provides the basis for excellent new methods to bridge the gap between microanatomical details revealed by LM and EM methods. When combined with electron tomography, investigators can derive accurate 3D data from these thicker specimens. Through the use of correlated light and electron microscopy, 3D reconstructions of large cellular or subcellular structures can be obtained with the confocal microscope,
A Transportable Multiple Oblique Illumination System which Retrofits to Conventional Optical Microscopes to Provide Highdefinition Real Time 3-Dimensional Imaging
Authors: Greenberg Gary L , Boyde Alan
Published: July 2020

Microscope specimens are 3-dimensional objects, but the images from conventional light microscopes are flat - they only show two dimensions. Multiple oblique illumination is a novel lighting technique for transmitted light microscopes that produces multiple (i.e. two or more) high definition 3-dimensional images using conventional microscope objective lenses. We have previously described its use in transmitted light. The same optical theory has now been expanded to include reflection microscopy. In the present paper, we describe a new development which will make this approach more widely available. It is a retrofit illumination system that will produce true 3-dimensional images directly through the eyepieces of conventional microscopes.

By seeing z-axis information in real-time and in the context of a specimen's entire thickness, researchers can gain additional, unambiguous information about the interrelationships between structures, whereas critical information about 3-dimensional structures can be obscured, lost or misinterpreted when using 2-dimensional instruments. The importance of accurate z-axis information has popularized methods such as deconvolution and confocal microscopy.
Structure and Action of Molecular Tracks and Motors
Authors: Milligan RA
Published: July 2020

Molecular motors belonging to the myosin and kinesin superfamilies utilize ATP to move along their respective F-actin and microtubule tracks. The track-motor complexes have not been amenable to crystallization, so x-ray crystallographic investigations have focused on structure determinations of the individual proteins. Although providing detailed descriptions of the structure of each protein, this approach cannot reveal the geometry of interaction of the proteins nor the conformational changes which occur during the mechanochemical cycle. To obtain this information, we use cryoelectron microscopy and image analysis to calculate three dimensional maps of the track-motor complexes at moderate resolution (15-30A) and combine these data with the high resolution x-ray structures to provide near-atomic models of the working assemblies.

We have so far built models of the rigor (nucleotide-free) and ADP actomyosin complexes. In smooth muscle myosin II (a collaboration with H.L. Sweeney, U. Perm.) and brush border myosin I (BBMI), the motor domain of the myosin head is similar in both biochemical states.
Cathodoluminescence Microscopy of Architectural Paint Samples
Authors: Hopen Thomas J , Brown Richard S , Wheeles R Keith , Stocklein Wilfried
Published: July 2020

The layer sequence of multi-layered white and off-white paint chips usually encountered by the forensic scientist in cases involving structural and/or maintenance paint is sometimes difficult to discern when utilizing commonly employed microscopical methods. This layer sequence information becomes vitally important when comparing a questioned paint sample to a paint sample of known origin. Techniques such as reflected light microscopy, fluorescence microscopy, and scanning electron microscopy (SEM) coupled with energy dispersive x-ray spectroscopy (EDS) may not provide the needed discrimination. Also, binder information may not be available for comparison since the thinness of the layers the difficulty in detecting individual layers, and the abundance of the extender pigments may preclude analysis by infrared microspectrophotometry.

Cathodoluminescence microscopy (CLM) may provide the needed layer sequence information and discrimination when analyzing and comparing multi-layered white and off-white paint samples. Cathodoluminescence (CL) is the emission of radiation from the sample in the visible light region and neighboring wavelengths during excitation by electrons generated from a cathode electron gun.
High Resolution FIB as a General Materials Science Tool
Authors: Phaneuf MW , Li J , Malis T
Published: July 2020

Focused Ion Beam or FIB systems have been used in integrated circuit production for some time. The ability to combine rapid, precision focused ion beam sputtering or gas-assisted ion etching with focused ion beam deposition allows for rapid-prototyping of circuit modifications and failure analysis of defects even if they are buried deep within the chip's architecture. Inevitably, creative TEM researchers reasoned that a FIB could be used to produce site specific parallel-sided, electron transparent regions, thus bringing about the rather unique situation wherein the specimen preparation device often was worth as much as the TEM itself.

More recently, FIB manufacturers have concentrated on improving the resolution and imaging characteristics of these instruments, resulting in a more general-purpose characterization tool. The Micrion 2500 FIB system used in this study is capable of 4 nm imaging resolution using either secondary electron or secondary ions, both generated by a 50 kV liquid metal gallium ion source.
Morphological Identification of Indicator Viruses from a Ground Water Aquifer Recharged with Reclaimed Wastewater
Authors: Stewart JR , Sobsey MD , Gambling TM , Carson JL
Published: July 2020

Protection of public health requires routine monitoring of environmental waters for fecal contamination, especially waters serving as drinking supplies. Municipalities typically rely on assays of indicator microorganisms to detect fecal contamination. Ideally, indicators and pathogens share a common origin. However, the indicators should have higher numbers, survive longer, and be easier to detect and quantify in the laboratory than pathogens. Coliform bacteria are the standard microbial indicator currently used in the United States. Enteric viruses are smaller and survive longer than coliform bacteria, therefore they are inadequate indicators of enteric viruses. Enteric bacteriophages, viruses infecting bacteria, may be a more reliable indicator for human viral pathogens. However, there are several taxonomic groups of enteric bacteriophages, all of which may not be good virus indicators. This project examines the ecology of coliphages, bacteriophages infecting Escherichia coli, in a ground water aquifer which serves as a municipal water supply.
Structural Changes of Soot Particulates as Shown by HRTEM and Image Analysis
Authors: Palotás Árpád B , Bell David C , Rainey Lenore C , Vander Sande John B
Published: July 2020

It has long been known that carbons have order at the microcrystalline level. Soots have been characterized as having a turbostratic structure and chars have been described as crumpled sheets. The value of electron microscopy in studying the morphology of such materials has been well established although only a few attempts have been made toward quantification.

The Methodology is based upon High Resolution Transmission Electron Microscopy (HRTEM) and further image analysis. The HRTEM image of each sample is recorded, digitized and processed with an image analysis software. Computer generated diffractograms are produced through Fourier Transformation and subsequent reverse transformation yields two color ‘extracted structures’ (Figure 1). The extracted structure is then undergoes statistical analysis. The analysis is aimed at identifying quantifiable structural parameters. Currently the following parameters are studied: circularity (C), elongation (E), and length of fringes (La) orientation of the fringes (cti), the inter-layer spacing (d002), and the fractional coverage of the extracted pattern (F).
Corrosion Product Identification by Micro-Raman and Mossbauer Spectroscopy
Authors: Adar F , Lenain B , Cook D C , Oh S J
Published: July 2020

Micro-Raman spectrometry and Mossbauer spectroscopy have been used to identify the corrosion products on a steel coupon exposed in an industrial environment for 16 years. The Raman analysis was performed on a polished metallographic cross-section in order to map the oxides across the thickness of the coating. The spectra were recorded using a LabRam Micro-Raman spectrograph incorporating a 17 mW HeNe laser (attenuated to 1 mW to prevent oxide transformation), focused to 1 μm spot size, and 1800 g/mm grating. The confocal line-scan imaging enabled 100 spectra to be recorded in one scan at 0.5 um intervals across the thickness of the coating. The Mossbauer analysis was performed using in-situ scattering Mossbauer spectroscopy on the attached corrosion coating and transmission Mossbauer spectroscopy at 300K and 77K on the removed coating, to measure the fraction of each oxide present. Micro-Raman spectrometry showed that the corrosion products had formed in distinct layers as shown in Figure 1.
Relocating Features Across Microanalytical Instrumentation
Authors: Powers William H , Schamber Frederick H
Published: July 2020

The ability to investigate a particular feature or region of a specimen using differing kinds of analytic instrumentation can be a very valuable technique. For example, an object viewed under an optical microscope provides color, polarization, and reflectance information which is not available via SEM viewing. Similarly, the SEM with its large depth of field and ability to utilize secondary and backscattered electron contrast mechanisms, and its capability to perform compositional analysis via EDS, provides information which the optical microscope cannot. Thus, the information provided by the two instruments is complementary.

Desireable though it may be to view the same feature of a specimen via differing instruments, this is often difficult to execute in practice. The difference in contrast mechanisms which makes the excercise valuable may also make it difficult to relate the distinguishing features viewed under one instrument with those viewed in the other. Further, the issue of scale creates a large complication in many practical instances.
Microstructure and Microchemistry of Y-Doped a-Al203
Authors: Giilgiin M A , Mulvihill M L , Putlayev V , Riihle M
Published: July 2020

A thorough microstructural study of common ceramics requires analysis at various length scales. Yttrium doped, polycrystalline α-Al203 was studied using a broad selection of microscopy techniques over a scale range covering seven-orders of magnitude (i.e. from mm to Å).

Yttrium doped, (1000 (Y/Al) atomic ppm) polycrystalline alumina samples were prepared by hot pressing at 1450°C at 50 MPa. Some were subsequently crept in tension. Microstructure of these samples was studied by optical microscopy, scanning electron/orientation imaging microscopy (OIM™), conventional and high resolution transmission electron microscopy. Analytical electron microscopy was performed on a VG HB501 FEG-STEM equipped with an EDS and PEELS.

On a large scale, the microstructure often consisted of bimodal sized alumina grains and second phase YAG (Y3A15012) precipitates. YAG precipitates at grain boundaries (GB) and triple points caused clusters (50μm to 1mm) of small equi-axed alumina grains (0.5-2 μm) randomly distributed over 40 area% of the sample.
The Complementary Nature of Electron Microscopy and ION Channeling for the Assessment of Radiation Damage Evolution in Ceramics
Authors: Sickafus K E
Published: July 2020

In ion irradiation damage studies on ceramics, damage evolution is often assessed using Rutherford backscattering spectroscopy and ion channeling (RBS/C) techniques. In a typical experiment, a single crystal ceramic sample is irradiated with heavy ions and then the crystal is exposed to He ions along a low-index crystallographic orientation. Simultaneously, the backscattered He ion yield is measured as a function of ion energy loss. For He ions scattered from the heavy ion irradiated volume, the He ion yield increases in proportion to the heavy ion dose. The RBS/C yield rises because the He ion beam is dechanneled by, for instance, interstitial point defects and clusters and their associated strain fields. A quantitative measure of dechanneling is denoted by χmin, defined as the ratio of the He ion yield along a low-index crystal orientation, to the yield obtained in a random (non-channeling) orientation. The damage parameter xmin varies from 0 to 1, where 1 represents the maximum damage level that can be measured by RBS/C.
TEM Analysis of Diamond Films Formed on SiO2 Substrate by Biasenhanced Nucleation
Authors: Cheng S C , Irwin M D , Onneby C , Pantano C G
Published: July 2020

Substrates of fused silica or other refractory glasses are of interest for the fabrication of diamondbased electronic sensors (such as thermistors) and field-emitter arrays. For temperature-sensing applications, the diamond thin film layers must be deposited on thermally insulating substrates, in order to optimize the accuracy and dynamic response time of the device. Silica and silicate glasses are good insulators, providing a barrier to the heat flow out of the device and thereby allowing for optimized performance of temperature sensors. Also, fabrication of diamond field emitters on large area glass substrates is important for manufacture of field emission flat panel displays. Recently, it has been demonstrated that significant enhancement of diamond nucleation on Si02 substrates can be achieved by applying electrical bias to the substrate during its exposure to a microwave generated CH4/H2 plasma.

To investigate the nucleation mechanism of diamond on Si02 substrate, induced during the biasing pretreatment, several TEM techniques were used to characterize the films and the film/substrate interface.
Observations of Superlattice Reflections Associated with Charge Ordering in Bi0.2Ca0.8MnO3 with an Energy-Filter
Authors: Murakami Y , Shindo D , Hiraga K , Oikawa T , Kersker M
Published: July 2020

A perovskite manganese oxide of Bi0.2Ca0.8MnO3 exhibits charge ordering of Mn3+ and Mn4+ ions upon cooling. This is an interesting phenomenon from both academic and practical viewpoints, since the charge ordering is accompanied by significant changes in both electric and magnetic properties of the oxide. Since a difference of scattering amplitudes between Mn3+ and Mn4+ is quite small, charge ordering can be observable as superlattice reflections due to the lattice strain caused by this ordering with an electron diffraction method. However, the background in an electron diffraction pattern, which is mainly caused by plasmon scattering, has hindered a precise investigation of the weak diffuse scattering. The purpose of the present work is to assess an efficiency of an omega-type energy-filter in detailed observations of the weak superlattice reflections associated with the charge ordering.

Specimens of Bi0.2Ca0.8MnO3 were prepared by a conventional ion-milling technique. The critical temperature of charge ordering (TCo) was determined to be 160K by resistivity and magnetization measurements.
Electron Energy-Loss Spectroscopy (EELS) of Cerium and Uranium Oxidation States
Authors: Keller Lindsay P , Bradley John P
Published: July 2020

EELS is a powerful analytical tool for exploring the local solid state environment in materials. There is an extensive literature on EELS analysis of the transition elements and light elements, yet few EELS data exist for heavy elements with multiple oxidation states. We report here on EELS studies of oxidation state influences on near-edge structure in cerium and uranium compounds.

All materials analyzed for this study were embedded in low viscosity epoxy and TEM specimens prepared using ultramicrotomy. The thin sections (∼50 nm thick) were analyzed using a JEOL 2010 (200kV) TEM operated with a LaB6 filament and equipped with a GAT AN 666 parallel EELS spectrometer. EELS data were collected in image mode at 105X magnification with a collection semi-angle of ∼ 100 milliradians at a dispersion of 0.1 eV/channel. The full width at half maximum of the raw (unprocessed) zero-loss peak was 0.7 eV. Peak positions were calibrated by applying a known voltage to a drift tube.
Microstructure of Nb BASED A12O3 Composites
Authors: Scheu C , Dehm G , Kaplan W D , Garcia D E , Claussen N
Published: July 2020

Metal-ceramic composites possess a wide range of applications due to an increased fracture toughness and strength compared to monolithic materials. A better understanding of the correlation between properties and microstructure of these materials requires a detailed analysis of the phases which form during processing. This can be accomplished by using various transmission electron microscopy (TEM) methods. In this study Nb based AI2O3 composites were investigated. The composites were prepared by pressureless sintering 2 of compacts of attrition milled AI2O3 and prealloyed Nb(Al) powder mixtures. The addition of 7 wt.% of Al to the Nb powder is supposed to assist in rapid and complete sintering of the material. The microstructure was studied in detail by conventional TEM using selected area diffraction (SAD). The chemistry and structure of the occurring phases, second phase particles and grain boundaries were analysed by analytical TEM and high resolution TEM (HRTEM).