bluuebunny/crossref_metadata_2025 huggingface dataset:
Computer Graphics Challenges in Electron Microscope Tomography Visualization
Authors: Durkin James W
Published: July 2020

We are developing a collaborative research environment, the Collaboratory for Microscopic Digital Anatomy (CMDA), to provide remote access to the sophisticated instrumentation located at the Na-tional Center for Microscopy and Imaging Research (NCMIR). The project’s initial focus is the col-lection and analysis of data from NCMIR’s unique intermediate-high voltage transmission electron microscope (HVEM), an instrument expressly designed to obtain images from thick specimens con-taining substantial 3-D structure. Because of the electron optical characteristics of the microscope, its images represent a 2-D projection of the specimen’s 3-D structure. 3-D data is derived, using axial tomography, from a series of projections acquired as the specimen is successively tilted in small angu-lar increments. Visualizing the 3-D volume data generated by this procedure is a key challenge facing the project. Our experience suggests that existing visualization mechanisms are limited in their ability to fully access the data’s biologically interesting information.
What is the Future for Image Simulation?
Authors: Van Dyck D
Published: July 2020

The ultimate goal of high resolution electron microscopy is to determine quantitatively the atomic structure of an object. In this respect the electron microscope can be considered as an information channel that carries this information from the object to the observer. High resolution images are then to be considered as data planes from which the structural information has to be extracted.

However this structural information is usually hidden in the images and cannot easily be assessed. Therefore, a quantitative approach is required in which all steps in the imaging process are taken into account. Two main approaches have been followed so far in the literature: the indirect approach in which the images are simulated for various plausible trial structures of the object and compared with the experimental images, and the direct approach in which the lost phase information is retrieved using holographic techniques so as to “deblur” the effect of the microscope and to reveal directly the atomic structure of the object.
Richardson Plots for Fractal Dimension Characterization of Bound Aries of Digitized Grains and Particles
Authors: Bright DS
Published: July 2020

Fractal dimension is useful for characterizing objects with tortuous boundaries, providing an additional measurement to characterize shape beyond the commonly used area, perimeter, caliper diameter and their combinations. The fractal dimension of the boundary describes the increase of the measured value of the perimeter of an object resulting from increasing measurement resolution, i.e., decreasing step size. We desire to characterize and classify shapes such as soot particles, as shown in the TEM micrograph in Fig. 1a, and crystalline grains of metal alloys, as shown in the SEM micrograph of Raney nickel in Fig. 4.

This investigation involves evaluation of the Minkowski-sausage or dilation technique (Fig. 1) using the histogram of the Euclidean distance map of the perimeter of the object. The distance map gives bands of various widths that follow the perimeter - greater widths lose detail. Perimeter length is sausage (band) area divided by sausage width, w.
Detailed Calculations of Thermal Diffuse Scattering
Authors: Bailey GW , Dimlich RVW , Alexander KB , McCarthy JJ , Pretlow TP , Müller DA , Edwards B , Kirkland EJ , Silcox J
Published: July 2020

Convergent beam electron diffraction (CBED) produces a diffraction pattern from a single point on the specimen using a focused probe in the scanning transmission electron microscope (STEM). Because the incident wavefunction is a focused probe, each diffraction spot is enlarged to a disk the size of the objective aperture. Thermal vibration in the specimen reduces the intensity of the diffraction disks and introduces scattering in between the disk. This normally forbidden scattering between the diffraction disks is referred to as thermal diffuse scattering (TDS). The effects are most pronounced at large scattering angles, where TDS scattering can greatly reduce the intensity of the higher order Laue zone (HOLZ) lines. Previous work on modeling the TDS intensity involved the so-called frozen phonon method and the Einstein model of lattice vibration. The Einstein model assumes that each atom in the specimen vibrates independently of every other atom in the specimen and possible correlations among adjacent atoms are ignored.
Ultimate Resolution Limits - Nanotips and Atom Lenses
Authors: Bailey GW , Dimlich RVW , Alexander KB , McCarthy JJ , Pretlow TP , Spence JCH
Published: July 2020

The most useful classical definition of resolution is a property of an instrument alone, independent of the sample. Because of this it is not possible to define resolution simply for HREM or for most of the new microscopies. For weak phase objects, the best current HREM machines offer a point resolution very close to 0.lnm. For the first time, recent off-axis electron holography has extended resolution beyond the point resolution limit, in fulfillment of Gabor’s original aim. Other recent approaches to super-resolution have used through-focus series under highly coherent conditions, sums of images obtained under different illumination angles, dark-field STEM imaging with high-angle detectors,thin annular detectors in STEM, or the use of coherent nanodiffraction patterns. Aberration correction by electron optical means has undergone a recent revival, and the effects of third-order astigmatism are under study. If third-order spherical aberration is corrected, the projected charge density approximation may be more useful than the weak-phase object approximation, since the Scherzer focus then no longer applies.
Resolution in Light Microscopy
Authors: Tandler H , Schreiber L , Simon U , Keller H E
Published: July 2020

The resolution in conventional light microscopy was defined by Abbe as: Wavelength (λ) and Numerical Aperture (NA) have a direct influence while the factor (c) is dependent upon the geometry of the illumination and observation beam paths. Some typical examples are:

High illumination apertures in darkfield or oblique illumination or specific ratios between illumination and observation aperture can substantially improve resolution. Various shapes of the illumination aperture, annular, point, centered or off axis at different azimuths directly influence numerical aperture and coherence and with this resolution, contrast and depth.

In mirror objectives low apertures become vignetted, the resolution is enhanced at the expense of contrast. In studies of Hopkins and Barham the factor “c” can range from 0.5 to 0.8. For the practically attainable condition, where illumination and observation aperture are identical, “c” becomes 0.61 and we have partial coherence.

Exceeding the observation aperture on the illumination side reduces “c” further but diffraction significantly reduces contrast.
What Do we Really See? Resolution in Near-Field Optical Microscopy
Authors: Isaacson MS
Published: July 2020

Six years ago there was a symposium held at the 1991 EMS A meeting to discuss the issue of “Resolution in the Microscope”.1 In this paper, we will look at resolution in near-field imaging, a blossoming field, and see whether any of our concepts have changed.

It has been only within the last decade that the concept of super-resolution microscopy in the near field has been vigorously pursued and experimentally demonstrated. (For reviews on the subject, the reader is referred to the proceedings of the second and third international conferences on near field optics.) However, as in most areas of microscopy, the idea is not new, but rather rediscovered after decades of dormancy.

The idea of optical resolution unhindered by far-field diffraction limitations was conceived more than a half-century ago by E.H. Synge4 in a paper entitled “A Suggested Method for Extending Microscopy Resolution into the Ultra-Microscope Regime”.
The Limits of Resolution in X-Ray Microscopy
Authors: Maser J , Jacobsen C , Spector S
Published: July 2020

In far-field microscopes, the spatial resolution is ultimately limited by the wavelength of the radiation used. While near-field and related microscopes can improve upon this, they can only do so with thin specimen regions. Thin specimens can also be studied at atomic resolution using electron microscopes. To achieve improved resolution on micrometer-thick specimens, another alternative is to use significantly shorter photon wavelengths. We discuss here the use of soft x-rays for microscopy and their resolution limits.

Image formation requires resolution and contrast. by using soft x-rays with a photon energy between the K absorption edges of carbon and oxygen, one is able to image hydrated biological specimens with high contrast. The contrast is such that no addi-tional staining is required, while efforts are also underway to utilize gold and luminescent probes for selective labeling. In addition, x-ray sources have high spectral resolution and good signal-to-background relative to electron microscopes which allows for elemental and chemical state mapping of major constituents.
Transport of Secondary Electrons Through a Film of Condensed Water; Implications for Imaging Wet Samples
Authors: Bache I C , Thiel B L , Stelmashenko N , Donald A M
Published: July 2020

We have performed a theoretical and experimental study of the the effect that a surface layer of condensed water has on the emission of secondary electrons from the surface. This is an issue of considerable interest to users of the Environmental SEM (ESEM) when imaging wet samples. Previous work has been performed to investigate the effect of a layer of water on back scattered electrons (BSE), but secondary electron (SE) imaging is more commonly used in ESEM, so an understanding of the interactions of SE with water is important. The aim of this work is to quantify the thickness of water through which imaging is possible, by considering both the interactions of secondary electrons with the water, and the interactions of the water layer with the sample, which may affect the secondary electron emission coefficient, δ.

The effects that a surface layer of water may have on electron emission from a sample surface can be split into three regimes.
Characterization of Contamination Effects on Polyimide Film Fracture Using Environmental Scanning Electron Microscope
Authors: Li M J , Taylor M E
Published: July 2020

Polyimide films have been used in many applications for their excellent mechanical, thermal mechanical, electrical, and chemical properties. In microelectronic industries, for example, polyimide films are utilized as dielectric materials in high density interconnects, passivation layers for semiconductor devices, and substrates for flexible printed circuits. One of the major concerns in these applications is the degradation due to deficient environments in fields. The change of environmental conditions, such as temperature, relative humidity, and containmination, may affect mechanical or electrical performance of the films. Cracking, warpage and delamination have been reported in recent years. Temperature and humidity effects have been investigated in previous studies. In this work, containmination effects on polyimide film cracking and fracture are investigated using an environmental scanning electron microscope (ESEM) with a tensile substage and a low-magnification device.

The ESEM (ElectroScan) enables examining non-conductive materials without conductive coating which maintains the materials in its natural state.
Variations in the Probe Beam Broadening with Operating Conditions in ESEM: Monte-Carlo Simulations and Edx Measurements
Authors: C. Bache I , Kitching S , Thiel B L , Donald A M
Published: July 2020

An understanding of the scattering of an electron beam as it passes through a volume of low pressure gas is of critical importance for users of Low Vacuum and Environmental Scanning Electron Microscopes (LV-SEM & ESEM respectively) The ‘skirting’ of the primary beam as a result of scattering is of particular importance in X-ray microanalysis where scattered electrons, falling onto the sample away from the probe beam, can adversely affect the spatial resolution of the X-ray signal. A number of studies have attempted to quantify the width of the probe beam experimentally and hence determine optimum microscope operating parameters. Theoretical and computational work modelling the interactions of the beam with the gas have suggested that the shape of the probe beam can be modelled by some form of Gaussian. Experimental measurements, however, suggest that the probe has a skirted form rather than a Gaussian one.
Sensitivity of SEM/EDX to Detect Small Particles on Substrates.
Authors: Thornton. MF
Published: July 2020

The characterization of microscopic particles on substrates is of interest in numerous scientific fields. One example is semiconductor device defect review, where the characterization of particles or defects on a device is an essential aid in tracing sources of contamination in the production process. With the ever decreasing component separation on the integrated circuits the sensitivity of SEM/EDX to detect small particles on substrates is an important issue. The minimum size of particles causing defects in semiconductor device manufacture is predicted to decrease from 0.12µm today to 0.02µm by the year 2010. The question of interest is how long the SEM/EDX analysis tool can continue to be used to identify elements present in “killer” defect particles of ever decreasing size? This paper attempts to address this question.

It has already been shown that films as thin as a monolayer can be detected with WDX provided high beam currents are available.
Use of Low Voltage High Resolution SEM (LVHRSEM) to Reveal Architectural Organization of Bone Mineral
Authors: Benezra V , Spector M , Hobbs LW
Published: July 2020

Load-bearing tissues in different organ systems display a wide variety of mechanical properties, yet are composed of only a few different molecules, with collagen as the principal structural protein. In bone, a mineral phase comprising carbonate-apatite crystallites confers compressive and torsional strength. The arrangement of collagen and apatite into three-dimensional hierarchical composite structures enables the tissue to bear high loads while maintaining flexibility. Moreover, bone serves as the body’s chemical storehouse for non-collagenous proteins and smaller molecular weight anions and cations such as calcium.

An understanding of the three-dimensional structure of the apatite phase at the nanometer and micrometer levels can provide insights into the properties of bone, and serve as the guide for the development of bone substitute materials. Transmission electron microscopy (TEM) has been valuable in revealing certain ultrastructural features of the mineral. However, it has not yet been possible to obtain three-dimensional reconstructions of the morphology and distribution of the apatite phase of bone using this method.
Chromium Coating for High Resolution SEM
Authors: Chen Ya , Wokosin David
Published: July 2020

High quality imaging of the macromolecular structure of biological samples can be obtained when combining high resolution SEM with advanced thin metal film coating techniques. A thin layer of fine grain metal film is often necessary to enrich the secondary electron (SE) signal generation and to enhance the contrast of features of interest, because the yield of SE signal from biological samples is low. Secondary electron signals, types SE-I and SE-II, are generated by primary beam at the impact point or by backscattered electrons (BSE) dislocated from the impact point, respectively (Peters, 1982; Joy, 1984). The SE-II signal yield depends on the amount of BSE signal and the collection ratio of SE-I/SE-II components regulates the surface topographic contrast. Therefore, the low atomic number metals with low backscattering coefficients should be considered for high resolution SEM coating. Chromium, which has both the features of low atomic number (Z=24) and sufficient SE signal yield, is an appropriate choice and was first used by Peters (1982) for high resolution SEM imaging.
Effect of Staining on Latex Particle Size Examined by Electron Microscopy
Authors: Ming Y , Doumaux H , Scriven L E , Davis H T
Published: July 2020

Electron microscopy has been an invaluble tool to the study of polymer morphology, especially latex particles, microphase-separated block copolymers, and polymer blends. However, in order to examine these materials in an electron microscope, the sample often needs to be stained to heighten contrast between locales of different composition in the specimen. Staining usually has the following advantages: heightened contrast; higher polymer glass transition temperature Tg; lowered charging; and reduced radiation damage. However, staining can also introduce artifact. It is reported that the latex particle size is raised and the polybutadiene “sphere” in block copolymers is lowered after staining. This indicates that the staining process may be complex.

Recently, low voltage field emission scanning electron microscopy (LVFESEM), especially high-resolution backscattered electron imaging produced with staining, has been used to study latex film formation, latex particle deformation and adhesion on substrates, latex particle deformation, distribution and binding in paper coatings.
Characterization of Ceramic-Based Dual Ultramicroelectrodes by Microscopic and Electrochemical Methods
Authors: Bailey GW , Dimlich RVW , Alexander KB , McCarthy JJ , Pretlow TP , Bums F M , Giolando D M , Kirchhoff J R
Published: July 2020

Recent trends directed toward the miniaturization of electrodes have produced ultramicroelectrode (UME) devices. Interest in UMEs is due to the considerable improvement in the quality of the electrochemical information that is obtained as the dimensions of the electroactive surface decreases. UMEs exhibit increased sensitivity to analytes, decreased response time, and enhanced single-to-noise. In addition, solution resistance has a decreased influence on the signal. Finally, the reduced size of UMEs allows electroanalysis in small sampling environments. As a result, UMEs have been used in applications for intracellular electroanalysis, as detectors in capillary separation methods and gas chromatography, and as electrochemical probes in scanning electrochemical microscopy.

While UMEs have been investigated since the early 1980s, single probe dual UMEs are a recent development. Dual UMEs have two independent UMEs in close proximity, which allows much flexibility in the design of electrochemical-based sensor devices.
Clostridium Spore Attachment to Human Cells
Authors: Panessa-Warren B , Tortora G , Warren J
Published: July 2020

This paper uses high resolution scanning electron microscopy (SEM) with a LaB6 gun and the newest commercial field emission guns, to obtain high magnification images of intact clostridial spores throughout the activation/germination/outgrowth process. by high resolution SEM, the clostridial exosporial membrane can be seen to produce numerous delicate projections (following activation), that extend from the exosporial surface to a nutritive substrate (agar), or cell surface when anaerobically incubated in the presence of human cells (embryonic fibroblasts and colon carcinoma cells). Magnifications of 20,000 to 200,000Xs at accelerating voltages low enough to minimize or eliminate specimen damage (1-5 kV) have permitted the entire surface of C.sporogenes and C.difficile endospores to be examined during all stages of germination. The relationships between the spore and the agar or human cell surface were also clearly visible.

Clostridium sporogenes ATCC 3584 and C.difficile ATCC 43594 and 9689 were grown in cooked meat media, filtered and cleaned.
Surface Characters of Interfaces and Twin Domains: TEM and AFM Study of a Feldspar Crystal
Authors: xu Huifang
Published: July 2020

Alkali feldspar, a framework silicate (K, Na)(Si3Al)04, is a common component in ceramic materials. The feldspar crystals commonly display exsolution lamellae, twins, and modulated structures. The boundaries between neighboring domains may cause stain energy. The domain structures cause heterogeneities both inside crystals and on crystal surfaces in aspects of structure, composition, and surface microtopography. Reactivity at domain boundary positions is different from the neighboring areas. More and more studies show the effects of microtopography on the surface reactivity. It is important to reveal the surface characters or microtopography of domain structures in crystals, and their effects on local reactivity.

Results from transmission electron microscopy (TEM) characterization show it contains exsolution lamellae (both K-rich and Na-rich lamellae) and twin domains in the Na-rich lamellae (Fig. 1A). Its SAED pattern shows reflections from both K-rich and Na-rich lamellae (Fig. B). Splitted reflections result from the Na-rich lamellae wiht twin domains related by (010) mirror plane, i.e., albite twin law.
Micromechanical Behavior of Silicate Glass Films on Alumina Substrates
Authors: Zagrebelny A V , Carter C B
Published: July 2020

In polycrystalline liquid-phase sintered (LPS) alumina ceramics, intergranular phases have proved to have a profound effect on mechanical properties such as strength, toughness, plastic deformation, and high-temperature creep. The presence of such intergranular phases, can also influence the kinetics of many processes including sintering, grain growth, and phase transformations. As a result, the key to optimizing the performance of a ceramic material is frequently related to optimizing the properties of these grain boundary regions. In order to understand the interactions between the glass layer and the crystalline grains at a fundamental level, the amorphous material must be placed in contact with the crystalline ceramic as a thin film in a controlled manner. Preparation of such a glass phase in the thin-film geometry has also prompted the use of nontraditional mechanicaltesting techniques.

In the present study, interfaces between silicate glass and single-crystal α-Al2O3 have been studied using AFM and nanoindentation.
Slip Band Analysis by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM)
Authors: Okerstrom S , Geng W , Kramer D , Gerberich W
Published: July 2020

Fatigue is a common cause of failure in components subjected to cyclic stresses. Repeated loads much smaller than the yield stress of the material can cause a fatigue failure. One such component subject to cyclic stresses is a titanium heart valve housing. The valve is subjected to a low level of stress with each heart beat as a disc pivots and closes against the housing. Interest in the initiation of fatigue in such components was an impetus to examine surface plasticity and accumulated damage which could lead to fatigue initiation. Grade 4 titanium used in heart valves and pure titanium have been studied.

The three phases of fatigue are initiation of a crack, propagation, and catastrophic failure. Minimum defect size for crack propagation and failure are fairly well understood by scientists and engineers. However, the initiation portion of fatigue as a function of accumulated surface microplasticty is less well defined. SEM and AFM have been be used to evaluate microplasticity on the surface of titanium and correlate damage accumulation to the initiation of a crack.

Fully reverse loaded four point bend testing was conducted on a an electropolished pure titanium sample 15 mm by 5 mm by 1 mm thick. The sample was oxidized at 300°C for one hour prior to fatigue testing. The sample was fatigued for 25,000 cycles using a ±45N load.
Phase Contrast Imaging in Atomic Force Microscopy
Authors: Magonov Sergei
Published: July 2020

Phase detection in TappingMode™ enhances capabilities of Atomic Force Microscopy (AFM) for soft samples (polymers and biological materials). Changes of amplitude and phase changes of a fast oscillating probe are caused by tip-sample force interactions. Height images reflect the amplitude changes, and in most cases they present a sample topography. Phase images show local differences between phases of free-oscillating probe and of probe interacting with a sample surface. These differences are related to the change of the resonance frequency of the probe either by attractive or repulsive tip-sample forces. Therefore phase detection helps to choose attractive or repulsive force regime for surface imaging and to minimize tip-sample force. For heterogeneous materials the phase imaging allows to distinguish individual components and to visualize their distribution due to differences in phase contrast. This is typically achieved in moderate tapping, when set-point amplitude, Asp, is about half of the amplitude of free-oscillating cantilever, Ao. In contrast, light tapping with Asp close to Ao is best suited for recording a true topography of the topmost surface layer of soft samples. Examples of phase imaging of polymers obtained with a scanning probe microscope Nanoscope® IIIa (Digital Instruments). Si probes (225 μk long, resonance frequencies 150-200 kHz) were used.
Adhesion and Nanomechanical Studies by Interfacial Force Microscopy
Authors: Houston J E
Published: July 2020

Scanning probe techniques have shown dramatic growth recently and are presently making significant impact on surface and interfacial problems in material science. The Interfacial Force Microscopy (IFM) differs from other scanning force-probe techniques by its use of a self-balancing, zero compliance force sensor. This allows carefully controlled and mechanically stable force vs. interfacial separation measurements to be obtained which yield unique and valuable information concerning the interfacial adhesive bond and its failure, as well as enabling the study of the mechanical properties of materials, both on the nanometer scale. I will demonstrate the enhanced capabilities of the IFM by presenting two examples involving: 1) the bonding interaction between chemically distinct end groups on self assembling molecules adsorbed on both the sample and probe tip and 2) a study of the effect of morphological defects on the nanomechanical properties of Au(l 11) single-crystal surfaces

Interfacial adhesion is of extraordinary technological importance and has long been of intense scientific interest.
Implementation Of A Digital Microscopy Teaching Environment
Authors: Graef M De , Nuhfer NT , Cleary NJ
Published: July 2020

The steady evolution of computer controlled electron microscopes is dramatically changing the way we teach microscopy. For today’s microscopy student, an electron microscope may be just another program on the desktop of whatever computer platform he or she uses. This is reflected in the use of the term Desktop Microscopy. The SEM in particular has become a mouse and keyboard controlled machine, and running the microscope is not very different from using a drawing program or a word processor. Transmission electron microscopes are headed in the same direction.

While one can debate whether or not it is wise to treat an SEM or a TEM as just another black-box computer program, it is a fact that these machines are here to stay, which means that microscopy educators must adapt their traditional didactic tools and methods. One way to bring electron microscopes into the classroom is through the use of remote control software packages, such as Timbuktu Pro or PC-Anywhere. The remote user essentially opens a window containing the desktop of the microscope control computer and has all functions available. On microscopes with specialized graphics boards, integration of the image and control display for remote operation may not be straightforward, and often requires the purchase of additional graphics boards for the remote machine.
Microscopy, Electron Microscopy, Elemental Analysis, Image Analysis, Digital Photography, And Telepathology Applications In Pharmaceuticals Research
Authors: Argentieri G , Grosenstein P , Killary K
Published: July 2020

Light and electron microscopy are exceedingly versatile disciplines having many applications in pharmaceutical research. Many corporate and university facilities are organized with a centralized microscopy laboratory that serves the needs of many different investigators. This is also true at the Novartis Pharmaceuticals Corporation in East Hanover, New Jersey. A centralized microscopy laboratory is not only more efficient, but also most cost effective. The microscopy lab at Novartis is designed to meet the needs for a wide range of applications serving all of Research and Development. The lab contains seven functional areas for microscopy applications. A large preparation and processing area, necropsy, microtomy, TEM, SEM, wet and dry dark rooms, and an image analysis suite including telepathology, complete the lab.

Microscopy service is widely used in Pathology, Toxicology, Drug Discovery, Technical Research and Development, Production and Quality Assurance, and Compliance. Microscopy services have also been involved in marketing (packaging labels and commercials) for Novartis products.
Museum Applications For Scanning Electron Microscopy: From Mollusks To Meteorites
Authors: Klaus Angela V , Barnett William K
Published: July 2020

In addition to dinosaur bones and gem collections, the American Museum of Natural History (AMNH) is also home to nine academic research departments: Anthropology, Herpetology, Mammalogy, Earth and Planetary Sciences, Ichthyology, Ornithology, Entomology, Invertebrates, and Vertebrate Paleontology. Each of these departments supports curators, research scientists and assistants, graduate students, and post-docs engaged in a broad spectrum of research activities.

The Core Microscopy Facility houses a state-of-the-art Cold Field Emission SEM equipped with an energy dispersive x-ray spectrometer. This instrument is extremely versatile, as it must be in order to meet the challenges of a diverse imaging and microanalytical environment. Our applications run the gamut from high-resolution electron imaging of insect parts to quantitative x-ray microanalysis of 5 billion-year-old meteorites.

Mineral scientists, archeologists, anthropologists, and artifact conservators use X-ray microanalysis extensively at the AMNH. Current projects include the analysis of chondrites (meteorites that condensed at the same time as the solar system), Neolithic pottery remains, and pigment fragments from Native American artwork.
Magnetic Domain Wall-Microstructure Interactions In Low-Carbon Steel
Authors: Radmilovic V , Krishnan KannanM
Published: July 2020

Nondestructive evaluation of steels is both an important engineering need and a scientific challenge. Recent advances include a SQUID imaging technique that is capable of detecting small changes in stray fields at reasonable spatial resolution. The technique is motivated by the fact that the stray fields, determined by the underlying domain configurations in the material, would provide insight into the microstructure including defects, provided the interactions between the microstructure and the domain walls can be well understood.Initial work is being carried out on 1018 low-carbon steels, plastically deformed in a controlled fashion, with the goal of correlating SQUID images with magnetic domain images measured by Lorentz microscopy in a TEM.

Experiments were carried out in a CM200 FEG TEM using the OL field in low-mag (LM) mode, based on a procedure described by Verbist et al [1] and Daykin et al [2].
In-Situ Tem Dynamic Magnetizing Experiments Used To Identify The Pinning Centers In Hard Magnets Re13.75fe80.25b6 (Re=Nd, Pr).
Authors: Volkov VV , Zhu Y
Published: July 2020

The new JEOL 3000F high resolution electron microscope at BNL has been optimized for Lorentz imaging. The necessary field-free environment around the sample is obtained by switching off the objective lens in the free-lens control mode, and the associated reduction in magnification is compensated for by a Gatan post-column image filter (GIF) at ∼ 20x magnification. Fresnel imaging is obtained by defocusing with objective mini-lens (OM). The use of low angle diffraction with an aperture located at the back focal plane makes it possible to obtain Foucault images.

In-situTEM dynamic magnetizing experiments combined with Lorentz magnetrc microscopy both in Fresnel and Foucault modes were used to characterize the magnetic structure of some hard and relatively soft magnets, Nd13.75Fe80.25B6 and Pr13.75Fe80.25B6, prepared by different processing routes. The goal of these in-situexperiments was to develop a reliable and effective procedure to search for, identify, and classify the different pinning centers present in real magnets that accord with their “pinning power” versus applied magnetic field.
Magnetic Imaging Of Recording Media
Authors: Robert Sinclair  , Kai Tang
Published: July 2020

Magnetic recording forms the basis of one of the largest international industries. Electron microscopy has of course played a significant role in relating magnetic performance to the underlying microstructure. However, relatively little attention has been paid to the ways in which imaging of the magnetic structure can be correlated with processing conditions and microstructural parameters. The present research has been aimed to address this deficiency.

A method was devised to prepare samples with large electron transparent areas (e.g., 250 microns square) from real computer hard discs. Fresnel TEM images were taken in a Philips CM20 FEG equipped with a special Lorentz pole piece, and with the objective lens off. Upon defocusing, the ferromagnetic domain structure strikingly appears. The characteristics of the recorded tracks depend on the magnetic state of the disc prior to magnetic “writing”, and much information about the local direction of magnetization could be obtained from the nature of the magnetic “ripple” structure.
Lorentz microscopy of magnetic fine particles
Authors: Tanji T , Aoyama N , Yamamoto K , Hirayama T
Published: July 2020

Magnetic granular films, which consist of magnetic fine particles of nanometer size and a nonmagnetic matrix, have been of great interest for new magnetic materials. Their magnetic characteristics strongly depend on the fine structures, besides the combination of magnetic and nonmagnetic constituents, especially their surface topology and the particles size. Although the relationship between these fine topological structures and the macro-magnetic characteristics has been investigated systematically by many researchers, there has remained a desire to observe magnetic microstructures directly. We succeeded in observing the magnetic structure of fine particles in granular films using Lorentz microscopy.

Two kinds of specimens were observed. One was an Fe-Mo granular film. An amorphous film of Fe-Mo was prepared by dc magnetron sputtering on amorphous carbon thin films at a temperature below 180 K. The films were annealed at 770 K within an in-plane magnetic field. The other kind was an Fe-MgO granular film, where iron particles were embedded in a magnesium oxide single crystal.
Micromagnetic Simulations Of Domain Structures In Thin Films And Bulk Hard Magnets
Authors: Cai Zhi-Xiong , Zhu Yimei
Published: July 2020

The shape anisotropy of a magnetic thin film competes with the easy-axis anisotropy, which gives rise to different domain structures compared to the bulk magnetic materials. Recent Lorentz microscope and electron holography and differential-phase-contrast experiments show complex domain structures with features not found in bulk materials seen by magneto-optic method.

In this report we use micromagnetic simulation techniques to study the effect of thickness on the domain structure of magnetic thin films with various orientations relative to the easy axis and compare with those in the bulk materials. The results of the simulations can be used to compare with the data obtained using electron holography experiments to give us quantitative understanding of the domain structure in hard magnetic materials.

We model the magnetic films with an array of dipoles of size 16×l6×Lz, where Lz the thickness of the sample.
High Coercivity Mechanism Of The Die-Upset Hard Magnets Re13.75Fe80.25B6 (Re = Nd, Pr): Possible Correlation To Specific DefectMicrostructure
Authors: Volkov VV , Zhu Y
Published: July 2020

The magnetic properties of permanent magnets are sensitive to their microstructure. In particular, for the family of Nd(Pr)-Fe-B magnets a very different coercivity and energy products may be obtained by several processing techniques. It was experimentally found that a small excess of Nd over the exact phase composition of Nd2Fe14B plays an important role in obtaining high-energy products during the die-upset processing of the anisotropic hard magnets. However the specific role of the Nd excess on both magnetic structure and microstructure of these die-upset magnets is unclear and controversial. Answers to these questions may help to correctly address some major issues in materials science, e.g. how microstructure is related to magnetic structure of hard magnets, and how to optimize the performance of hard magnets.

In-situ TEM magnetizing experiments combined with Lorentz magnetic microscopy in Fresnel-Foucault modes were used to characterize the magnetic structure of die-upset, high energy-product hard magnets Nd13.75Fe80.25B6 and Pr13.75Fe80.25B6.
Semiconductor Defects And Thin Films Characterization By High-Resolution Images And By Vibrational Spectroscopy.
Authors: Conti G , Uritsky YS , Brundle C R , Xu J
Published: July 2020

The physical and chemical characterization of defects and particles on wafer surfaces gives important information on their origin. An effective approach for root-cause determination of wafer surface particle problems is to perform both high-resolution images and chemical characterization on individual defects. The traditional root-cause analysis technique used in the semiconductor industry is Scanning Electron Microscopy combined with Energy Dispersive X-Ray Spectroscopy (SEM/EDX). This technique provides high-resolution images and the atomic composition of the defects. However, this is sometime insufficient to fully characterize them and to determine their origin. In this case, the identification of the molecular composition of the defects can help determine their origin.

Optical spectroscopy, such as Infrared and Raman spectroscopy, is a powerful method for determining the molecular composition of many substances. Micro-FT-IR spectroscopy can characterize semiconductor particles only down to 10 μm because of the IR wavelength diffraction limit. Micro-Raman spectroscopy, instead, can provide useful molecular information on many organic as well as inorganic species with 1 μm spatial resolution.
Micro-Raman Spectroscopy In The Characterization Of Biomedical Materials
Authors: Huang Frank K
Published: July 2020

μ-Raman spectroscopy has been used to characterize two types of biomedical materials: a multilayer, silicone elastomer used in implants, and a thin, polyethylene layer used in a medical device. Raman spectroscopy is the collection of light inelastically scattered by a material or compound. The technique is based on the Raman effect, which involves the interaction of light and matter. When light strikes a material, the light is inelastically scattered and is frequency shifted according to the vibrations of the chemical-functional groups and/or macrostructure of the material. The result is a Raman spectrum of the material that can be interpreted to determine the characteristics of the material, including identity, macrostructure, and quantity of a specific material within a matrix.The application of Raman spectroscopy in the characterization of polymers has been well established. The technique has been used to determine the chemical composition and morphology of polymers. Raman spectroscopy could therefore be a powerful tool for characterizing polymeric biomaterials.

The silicone elastomer characterized in this work consisted of three layers: polydimethylsiloxane, polydimethyl/polydiphenyl siloxane, and polydimethylsiloxane.
Semiconductor Thin Film Characterization Via Raman Microprobe Spectroscopy: Analysis At The Process Line
Authors: Gotts Hugh E
Published: July 2020

Raman Microprobe Spectroscopy has been used in research laboratories to model the growth of thin film silicide layers and the re-crystallization of α-silicon, however little progress has been made towards using these techniques as either at line or on line tools.

At line and on line instrumental techniques such as ellipsometry and X-Ray Fluorescence have been used to characterize the physical properties of thin films in the semiconductor industry, which has lead to improvements in device yields. These techniques, however, do not provide the specificity to determine thin film phase changes which result in improved device performance, whereas Raman Microprobe Spectroscopy can monitor these changes.

In order to perform at line or on line measurements, the spectrometer must be moved to the process line floor. The recent improvements in spectrometer design which has produced systems robust enough to endure high technology manufacturing environments will be briefly discussed. Two case studies of semiconductor process monitoring via Raman Microprobe analysis will be presented.
Evaluation Of Diseased State In Human Tissue Sections Using Infrared And Raman Imaging Microspectroscopy
Authors: Neil Lewis E , Haka Abigail S , Colarusso Pina , Levin Ira W , Gillespie John , Kidder Linda H
Published: July 2020

Optical microscopy has been the workhorse pathological technique, qualitatively differentiating tissue sections by characterizing morphological variations. Vibrational spectroscopic techniques provide quantitative as well as qualitative analytical information that reflects a sample’s biochemical composition and molecular structure. The utility of infrared and Raman techniques for biological characterization has been demonstrated for a variety of applications.[1-4]

FTIR imaging microscopy is a newly developed technique that incorporates the imaging capabilities required for histological procedures with the chemical discrimination of IR spectroscopy.[5-7] The ability to maintain spatial integrity while accessing precise spectroscopic data intrinsic to the sample represents a powerful combination. This technique is much more amenable to analysis by a pathologist than conventional spectroscopy because the data can be presented as images. These images provide direct visualization of a sample’s biochemical heterogeneity.

Vibrational spectroscopic imaging techniques provide excellent sample statistics for the accurate classification of individual spectral signatures because tens of thousands of independent spectra from different spatial locations within the sample are simultaneously recorded.
Attenuated Total Internal Reflection Infrared Microspectroscopy For The Study Of Trace Contaminants In Aqueous Solutions.
Authors: Sommer Andre’ J , Hardgrove Mark
Published: July 2020

Over the past several years many developments have taken place in the field of molecular spectroscopy. For Raman spectroscopy many of the improvements have arisen from technological innovations that include diode-based lasers, holographic notch filters and charged coupled detectors. In contrast, a majority of the developments in infrared spectroscopy have been in the area of new sampling accessories. A major emphasis has been placed on attenuated total internal reflection (ATR) accessories. The devices are allowing infrared spectroscopy to be employed in process control environments and quality control laboratories where the method is not only robust but has the advantages of limited sample preparation and/or in situ analysis.

In the realm of microspectroscopy, ATR accessories have the added advantages of providing better spatial resolution, equal to or higher S/N for equivalent sample size compared to transmission measurements and most importantly the ability to collect spectra of small samples without the adverse effect of diffraction. One accessory which was developed several years ago is known as the Split-Pea.
Infrared Imaging: Performance And Applications Of An Ft-Ir Microscope Based Imaging System
Authors: Wright N A , Bhandare P S , Jiang E Y
Published: July 2020

The field of infrared imaging for analytical chemical analysis has developed over the last few years into a technique that has clearly demonstrated its utility in a variety of applications(l-6). This imaging system is based upon the coupling of an infrared array detector to an infrared spectrometer and microscope, where the use of an array detector allows both spatial and spectral information to be generated simultaneously. Because of the high spatial content and data acquisition speed, researchers have been able to apply this technique to samples and experiments where traditional infrared microscopy has not proven successful.

Previously, in order to obtain an infrared image, the researcher was required to undertake a step and collect mapping experiment. In the mapping experiment, an aperture is set to obtain the desired spatial resolution at the sample. If high spatial resolution is required, most of the energy is discarded and long data collection times are needed to obtain a reasonable signal-to-noise
Alternate Technique To Measure ϕ(ρz) Curves Of Insulator Orcompound
Authors: Drouin D , Nockolds C
Published: July 2020

The ϕ(ρz) method is commonly used in quantitative X-ray microanalysis to calculate the proper correction for absorption and atomic number. Several models are used to reproduce generated X-ray intensity as a function of mass thickness. Those models rely on equations which has been adjusted to fit experimental measurement of the ϕ(ρz) curves. The classical tracer method for the experimental measurement of ϕ(ρz) curves proposed by Castaing (1951). The limitations of this method are related to the fabrication steps of the sample. The successive layers must be deposited in thin uniform layers of the same mass thickness and must be the same composition as the substrate.

The method described here, first proposed by J. Cazaux, uses the effect of self-absorption in a bulk sample to determine the generated intensity. The basic idea is to produce a set of equations for several absorption conditions while maintaining a constant geometry for the x-ray generation.
Measurement And Simulation Of X-Ray Emission From Multilayered Structures In Electron Probe Microanalysis.
Authors: Merlet C , Llovet X , Salvat F
Published: July 2020

Studies of x-ray emission from thin films on substrates using an electron probe microanalyzer (EPMA) provide useful information on the characteristics of x-ray generation by electron beams. In this study, EPMA measurements of multilayered samples were performed in order to test and improve analytical and numerical models used for quantitative EPMA. These models provide relatively accurate results for samples consisting of layers with similar average atomic numbers, because of their similar properties regarding electron transport and x-ray generation. On the contrary, these models find difficulties to describe the process when the various layers have very different atomic numbers. In a previous work, we studied the surface ionization of thin copper films of various thicknesses deposited on substrates with very different atomic numbers. In the present communication, the study is extended to the case of multilayered specimens.

The studied specimens consisted of thin copper films deposited on a carbon layer which, in turn, was placed on a variety of single-element substrates, ranging from Be to Bi.