bluuebunny/crossref_metadata_2025 huggingface dataset:
TEM Microscopical Examination of the Stepped Bainite Reaction in Silicon Steels.
Authors: Fourlaris G , Papadimitriou G
Published: July 2020

The bainitic reaction in steels has been extensively studied, however it is still controversial whether it proceeds by a diffusional or a shear mechanism. In a previous investigation of the bainite reaction in a Fe-3.9Si-0.9C steel the transformation was considered to be the result of two competing elementary mechanisms, i.e., the shear transformation of the α-iron lattice and the diffusion of interstitial carbon away from the transformation interface.

In this paper, the microstructural and crystallographic characteristics of the bainite products obtained through the step quenching experiments are examined, using TEM and Electron diffraction. The results are compared to those obtained by the corresponding bainitic transformation in a single step. The results obtained here support the proposed model in and the shear character of the bainitic transformation.

The same steel as in, an alloy with 3.9 w.t.% silicon and 0.9 w.t.% carbon, was used. After austenitizing at 1130°C for 30 minutes a number of samples were transformed at 420°C for 30 minutes and subsequently quenched in a second bath where they were kept for times increasing from one to thirty days at temperatures of either 360,340 or 290°C.
Atom Probe Field Ion Microscopy of Model Ni-Al-Be Superalloys
Authors: Thomson R C , Russell K F , Miller M K
Published: July 2020

Nickel-based superalloys used in jet engines consist of a face-centred cubic Ni matrix, γ, containing a high density of Ll2-ordered Ni3Al precipitates, γ´. At high temperatures the strength of the alloy depends primarily on the strength of the γ´ phase, which begins to decrease above approximately 750°C, limiting the maximum operating temperature of the superalloy. The possibility of strengthening the γ´ phase by solid-state precipitation within the γ´ phase has been investigated in model Ni-Al superalloys containing Be. Beryllium, a light element, is also expected to be a potent solid solution strengthener in the γ´ matrix.

Four alloys were manufactured with compositions Ni-18.8 at. % Al-1.6% Be, Ni-19.0 at. % Al-2.6% Be, Ni-17.9 at. % Al-5.4% Be and Ni-15.9 at. % Al-11.9% Be. These Al levels result in a volume fraction of γ´ phase similar to that present in a commercial superalloy, and the Be addition places the superalloys in the γ-γ´-NiBe region of the ternary phase diagram, Fig. 1.
Orientation Relationships in the System Nb-NbCr2
Authors: Kotula P G , Chen K C , Thoma D J , Chu F , Mitchell T E
Published: July 2020

Laves-phase intermetallics are of potential use as high-temperature structural materials. NbCr2-based C15-structured alloys are of particular interest for such applications. by themselves, Laves phases generally have poor ductility and fracture toughness at low temperatures. Two phase alloys (i.e., Laves phase and the ductile bcc phase) are considered more promising for structural applications. The orientation relationships between the two phases can contribute to the mechanical behavior of the material. In this study, observations of two different orientation relationships in a Nb-NbCr2 eutectic are discussed and compared with previous studies of the NbCr2 system, as well as the TiCr2 system.

A Nb-NbCr2 eutectic alloy was prepared by arc-melting high-purity alloys followed by annealing at 1400°C for 100 h and then cooling at l°C/min. The complete details of the materials preparation have been given elsewhere. Specimens were prepared for observation in the transmission electron microscope (TEM) by cutting 3 mm discs with a coring saw, followed by dimpling and ion milling. Microstructural characterization was performed with a Philips CM30 TEM operating at 300 kV.
Charge Density Wave Modulated Structures in the Intercalated Tunnel Phases AyNb3X4 (A = In, Tl; X = Se, Te; 0 < y < 1)
Authors: Bennett JC , Boswell FW
Published: July 2020

Although the unusual microstructural and electronic properties of charge density wave (CDW) modulated compounds have been extensively investigated over the past two decades, many aspects of the complex behaviour of these systems remain unexplained. As a result, the characterization of a new family of CDW structures, in which the CDW properties can be widely varied in a predictable manner, is of experimental and theoretical interest.

The Nb3X4 (X = S, Se, Te) family of compounds is based on a hexagonal unit cell built up of edge and face sharing NbX6 octahedra (Figure 1). The structure is characterized by zigzag Nb-Nb chains and large hexagonal tunnels running parallel to the c-axis. One member of this family, Nb3Te4, is known to undergo a CDW phase transition at ∼100 K. A large number of metal atoms can be introduced into the tunnels to form a family of isostructural, intercalated compounds AyNb3X4. Electrical resistivity measurements on polycrystalline pellets of InyNb3X4 (X = Se, Te) have revealed temperature anomalies indicative of the formation of CDW in these materials.
A Micro Analytical Study of Interfacial Reaction Between Lead-Tin Solders and Palladium
Authors: Ghosh G
Published: July 2020

Palladium is widely used for metallization of electronic circuits and in electronic packaging. During soldering palladium dissolves in the liquid solder and form various intermetallics both at the solder/substrate interface and in the solder. Diffusion of atomic species lead to the formation of intermetallics in the solid state as well. As the dissolution and interfacial reaction continue, the solder comes in contact with other metallization layer(s) and eventually with copper. This leads to a very complex microstructural evolution process which ultimately affects the interfacial mechanics and transport properties. In order to improve the reliability of electronic packaging, it is necessary to understand and control the dissolution and solid-state reaction mechanisms between the metallization layers and currently used lead-tin solders. As a first step towards modelling and understanding this complex microstructural evolution, here we have undertaken a systematic study of interfacial reaction between lead-tin solders and palladium.

Pure Sn, Sn-38 mass% Pb and Pb-5 mass% Sn were used in this study.
Characterization of WC-VC-Co Cemented Carbides Using Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray Spectroscopy (EDS)
Authors: Arenas F , de Arenas I B , Ochoa J , - Cho S A
Published: July 2020

The two important constituents of metallic tool alloys are transition metal carbides and metals of the iron group, Fe, Ni, Co. Combining them, based on WC, it is obtained a hard and tough cutting tool material. Many attempts have been made to develop alternative cemented carbide systems by substituting a portion of WC by other hard phases. In this investigation, microstructure and phases composition of 90 mass% [ (1-y) WC - y VC ] - 10 mass% Co with y = 0, 0.2, 0.4, 0.6 and 1.0 sintered cemented carbides were studied by Backscattering electron (BSE) compositional images, elemental dot maps and X - ray microanalysis. These techniques have allowed to determine the different phases present, their morphology and composition.

Cylindrical samples of 10 mm. in diameter and height were manufactured by vacuum sintering at 1400°C of uniaxially pressed compacts at 350 MPa. Liquid phase sintering is the predominant consolidation mechanism present in this system.
Grain Boundary Microstructure of a Hot Isostatically Pressed Silicon Nitride
Authors: Fu L , Hoffmann M J , Pan X
Published: July 2020

Si3N4-based materials exhibit attractive mechanical properties for high-temperature applications. These properties are influenced strongly by the size and morphology of the grain boundaries and grain-boundary phase. An amorphous intergranular film (IGF) commonly exists at two grain junctions. The thickness of these IGFs sensitively depend on the chemical composition of the intergranular phase.In this work, our studies on the grain boundary microstructure of Si3N44 ceramics made by Hot Isostatically Pressing (HIPing).

Si3N44 materials were densified by HIPing Si3N4 powders (UBE E-10) at 1950°C at 200 MPa for 1 hour, with sintering aids of either Y2O3 or Y2O3 + A12O3. Two materials were made: material A consisting of 2 wt% Y2O3; material B consisting of 5 wt% Y2O3 and 1 wt% A12O3. Both as-HIPed and oxided samples were investigated. TEM specimens were prepared by conventional procedures. The microstructure and chemical composition were studied on a JEOL 2000FX.
Characterization of Boron Nitride Coated Silicon Carbide Fibers and Composites
Authors: Gopal Mani
Published: July 2020

Silicon carbide (SiC) composites are receiving much attention for structural use at high temperatures. One class of composites are those reinforced with SiC fibers. The SiC fibers are coated with boron nitride (BN) which is weakly bonded to the fiber. During fracture, the coating deflects cracks causing pull-out of the fibers (Fig. 1). This process of fiber pull-out consumes energy and increases the toughness of the composite. Although much work has been done on characterizing these materials by SEM, not much has been done using TEM due to difficulties in specimen preparation. The purpose of this study is to characterize these fibers and composites using conventional and analytical TEM.

In this study, TEM specimens were prepared by dimpling and ion milling. Careful control of the preparation was needed to ensure the integrity of the SiC-BN interface. Figure 2a is a TEM image of the fiber showing delamination at the SiC-BN interface.
Small Onions Formation Under Electron Irradiation of Turbostratic Bc2n and Turbostratic Bn
Authors: Stephan O , Bando Y , Kurashima K
Published: July 2020

After the discovery of C fullerenes and C nanotubes grown in the vapor phase, the formation of carbon onions [1] in the condensed phase from the irradiation of graphitic polyhedral particles with an intense electron beam gave further evidence that spherical carbon network can be favored under high temperature and strong irradiation regimes. Recently, BN and B-C-N hybrid nanotubes were synthetized. In spite of theoretical predictions, so far there has been no experimental evidence for the stability of B-N and B-C-N analogs of buckminster fullerenes. We exposed turbostratic BC2N and turbostratic BN samples to intense electron irradiation to study the ability of the honey comb network to include non hexagonal member rings and form curved structures.

In the experiments described here, the BC2N starting materials were synthesized from vapor phase reaction (CVD) of BC13 and CH3CN. Such samples were then exposed to high temperature-high pressure (HT-HP) conditions at 7.7.
Formation of Nickel Ferrite Films by Solid-State Reaction
Authors: Johnson Matthew T , Kotula Paul G , Barry Carter C
Published: July 2020

Nickel ferrite (NiFe2O4) thin films are of potential interest for magnetic applications. In the present study, the production of NiFe2O4 by solid-state reaction between thin films of hematite (α-Fe2O3) and nickel oxide (NiO) on (0001) sapphire (α-Fe2O3) substrates has been examined. The NiFe2O4 thin films were prepared by two different methods. In the first case the NiFe2O4film was grown in situ in the deposition system, while in the second case the NiFe2O4 film was formed ex situ by reacting at elevated temperatures in air. These two methods of reaction lead to interesting morphological differences in the ferrite layers.

Epilayers of α-Fe2O3 followed by NiO were deposited onto (0001) α-Al2O3 by pulsed-laser deposition (PLD) in 6 mTorr O2. NiFe2O4 films were obtained by reacting the starting films in two different ways: in situ (during film growth) and ex situ.. In both cases, the α-Fe2O3 films were grown under the same conditions while those for the deposition of the NiO layers were different.
The Dynamics of Mgo Surface Faceting
Authors: Yanina Svetlana V , Johnson Matthew T , Barry Carter C
Published: July 2020

The {001} surface of magnesium oxide (MgO) has been the focus of numerous studies, which were prompted by the importance of MgO for its use as a substrate for thin film growth and also as a chemical catalyst. In the present work, atomic force microscopy (AFM) was used for studying the dynamics of surface processes of MgO which occur at elevated temperatures. AFM was chosen, in part, because it allows for imaging of topographical details at the atomic level with minimal sample preparation. Additionally, because the surface morphology of the same area was traced through a series of heat treatments, scanning electron microscopy analysis would be difficult because no conductive coating could be used (such a coating may have altered the surface between subsequent heat treatments).

AFM images were recorded in contact mode, in air, on a Nanoscope III (Digital instruments, Santa Barbara, CA) using Si3N4 cantilevers (Ultralevers, Park Inst., Sunnyvale, CA) with a nominal applied force of 10-15 nN.
Contrasting Cation Distributions in Spinels of Similar Composition
Authors: Fernandes TRC , Echer CJ , Krishnan Kannan
Published: July 2020

Chromite mined from the Great Dyke in Zimbabwe is used for the production of about 180 000 tonnes of ferroalloy per annum, equivalent to about 6% of the world’s supply. The chemical and physical characteristics of the ores, which vary even within the same seam, affect the carbon content of the ferroalloys and hence their commercial value. The purpose of this study is to examine some of the differences between two extremes of chromitites, sheared and unsheared, used in the ferroalloy industry in Zimbabwe to provide a better understanding of the factors that influence the composition of the alloys as a basis for process mineralogy.

The ores consist of chromium spinels (MgAlCrFe)3O4 with a lattice of alternating non-equivalent planes of tetrahedrally coordinated A sites and octahedrally coordinated B sites. The distribution of five major cations (Mg2+, Al3+, Fe2+, Fe3+ and Cr3+) was examined by the technique of electron channelling.
Complementary Analysis Using Polarized Light and Scanning Electron Microscopy in the Determination of Sulfate Attack on Concrete
Authors: Park J I
Published: July 2020

A high water to cement ratio in concrete produces excessive porosity in the paste, thereby increasing the concrete’s susceptibility to sulfate attack and subsequent premature deterioration. Widely used as a building material, concrete experiences physical and chemical deterioration whose extent and nature may be determined by polarized light microscopy (PLM) and scanning electron microscopy (SEM). New software innovations allow exact image relocation in PLM and SEM, thereby producing complementary information which aids in analyst recognition and increases the effectiveness of each analytical technique.

Although overlapping information may be derived using both PLM and SEM, each technique has inherent advantages and disadvantages which complement the other. The advantages of PLM include a color image, good low magnification resolution providing a bridge between macro/micro analysis, and the ability to distinguish polymorphs and materials of nearly identical composition (e.g., solid-solution series components). Disadvantages of PLM include limited high magnification potential, mineralogical identification based on the analyst’s knowledge of optics, and the need for photographic attachments.
Reinvestgation of Tweed Microstructures in Annealed Albite
Authors: Kim Y J , Lee S H , Lee J C
Published: July 2020

Previous TEM study of natural Amelia albite (Ab99.3An0.1Or0.6) isothermally annealed at 1073°C for various periods revealed distinct tweed microstructures from the intermediately disordered albite samples (intermediate albite), but not from both the natural sample (low albite) and the highly disordered samples (high albite).1 These tweed microstructures seemed to correlate well with the degree of peak broadening and distortion in corresponding conventional powder X-ray diffractograms. Previous XRD, synchrotron radiation and TEM studies on the annealed albite samples at 1080°C for various periods gave rise to similar results.

Reinvestigation of the annealed albite samples with distinct tweed microstructures by TEM confirmed their existence in wide areas, giving two-directional streaking in the corresponding SADP’s (Fig. 1 and 2). Tweed directions are roughly perpendicular to and parallel to the trace of albite twin plane, {010}, as shown in Fig. 3. This tweed microstructure is apparently unaffected by the twinning and probably formed after it.
Analysis of Asbestos Fibres in The Scanning Electron Microscope (SEM) by The Use of Electron Backscattering Diffraction (Ebsd).
Authors: Raanes M , Hjelen J
Published: July 2020

Asbestos is a common name of a number of fibrous mineral silicates which differ in chemical composition. The asbestos fibres are classified into two groups: serpentine (chrysotile) and amphiboles (anthophyllite, amosite, actinolite, tremolite, crocidolite).

Inhalation of asbestos dust fibres involves a health risk. It is therefore of great importance to develop quick and reliable methods to check for the presence of asbestos fibres in suspected materials. Some common analysis methods for asbestos detection are: optical microscopy scanning or transmission electron microscopies (SEM,TEM) often combined with energy dispersive X-ray analysis (EDX) and selected area electron diffraction (SAED) in the TEM where the crystal structure is determined.

The EBSD technique in the SEM has in this work been applied to achieve electron backscattering patterns (EBSP) from four types of asbestos fibres. The pattern quality has been studied as a function of specimen preparation and SEM settings.
An Electron Microscopy Method for Bulk Sample Analysis for Presence of Asbestos
Authors: Daniel Barron  , Kecskes Laszlo J
Published: July 2020

A method has been developed to identify asbestos-bearing samples. This technique, using scanning and transmission electron microscopy (SEM/TEM) coupled with X-ray fluorescent spectroscopy (XFS), X-ray elemental spectral analysis (EDS/EDAX), and X-ray diffractometry (XRD), supplements the traditional use of dispersion staining and polarized-light optical microscopy. The traditional method is subject to a statistical variance associated with analyzing a small volume of sample and projecting the results to the entire volume of the sample which in many cases is non homogeneous. [1] The simultaneous use of the aforementioned analyses in the new method improves the quantitative identification of highly heterogeneous unknowns.

The primary purpose of this study was to determine the essential steps of the identification process that will serve as the basis in the development of an automated particle/fiber recognition program. Five commercially pure asbestos samples of actinolite, amosite, chrysotile, crocidolite, and tremolite, and four common ‘household’ samples were examined.
Unusual SEM Image Contrast from Corrosion Oxide Films of Zr-2.5%Nb Pressure Tube Alloy
Authors: Lin Y P , DeLuca J
Published: July 2020

Zr-2.5wt%Nb alloy is used as the pressure tube material in CANDU reactors. The pressure tube microstructure consists primarily of α-Zr (< l%Nb) grains elongated in the axial direction of the pressure tube and typically 0.3-0.5 μm thick in the radial direction. The α-Zr grains are partially surrounded by a thin layer of Nb-rich β-Zr phase (≈ 20%Nb). During corrosion, α-Zr is converted primarily to monoclinic ZrO2 with minor amounts of tetragonal ZrO2. Oxidation of α-Zr is complicated by the metastable nature of the phase below 863K. A detailed understanding of the nature of oxidized β-Zr remains a topic of on-going investigation, although some information have recently become available. Present SEM observations shed some lights on the charging characteristics of the oxidized β-Zr compared with ZrO2.

Oxide films on pre-polished surfaces perpendicular to the radial direction of the pressure tube were grown in steam at 673K in an autoclave; the treatment corresponds to the last stage of the pressure tube production.
Surface Analysis of Shear Strength Tested Tungsten Carbide Thermal Spray Coatings+
Authors: Bailey GW , Dimlich RVW , Alexander KB , McCarthy JJ , Pretlow TP , Naidu S V , Green Carlos , Maxie Christopher , Garber James D , Glass Gary A
Published: July 2020

Thermal spray processing has become an important powder-consolidation technique to yield new materials for extremes of temperature, radiation, wear, corrosion and mechanical stresses. High Velocity Oxy-Fuel (HVOF) spray coating process gives higher deposition densities and coating hardness; lower oxide content and porosity. The adhesive strength of thermal spray coatings is greatly effected by the interfacial impurities. The ring shear test method shown in Fig. 1 appears to give the most accurate results on shear adhesive strength. A typical ring shear test result of 88WC12Co 1/4" ring HVOF thermal spray coating on 4140 steel rod using a Jet kote thermal spray gun is shown in Fig. 2. Repeated ring shear tests on similar samples prepared under same spray and test conditions resulted in different shear bond strength and coating ring displacement before break off. We examined the ring shear tested coatings using a Zeiss DMS942 Scanning Electron Microscope (SEM) and Kevex Energy Dispersive X-ray Spectrometer (EDXS) with LPX1 Quantum Si(Li) Detector.
Attempts to Visualize Conformational Changes in a Single Protein Molecule During Function
Authors: Bailey GW , Dimlich RVW , Alexander KB , McCarthy JJ , Pretlow TP , Kinosita Kazuhiko , Yasuda Ryohei , Sase Ichiro , Miyata Hidetake
Published: July 2020

The operation of protein molecular machines is essentially stochastic. One cannot predict exactly when an ion channel opens, or when a molecular motor makes a step. As such, working molecular machines cannot be synchronized with each other in a rigorous sense. To understand the mechanism of a protein machine, therefore, one has to watch conformational changes of individual molecules while they are at work. To this end, we have been trying to develop two approaches based on optical microscopy. One is to attach a small tag, a fluorescent probe, to an appropriate site on the protein molecule of interest. Polarization of the probe fluorescence, for example, will reveal the orientation of the fluorophore, and thus of the portion of the protein molecule to which the fluorophore is attached. A conformational change of the protein will be detected as the reorientation of the fluorophore. A prerequisite is the ability to image a single fluorophore in an aqueous environment, which we have achieved on an epifluorescence microscope by reducing its background luminescence by two orders of magnitude
Simultaneous Optical Measurements of Cellular Membrane Potential and Volume in Epithelia
Authors: Gross Eitan , Hopfer Ulrich
Published: July 2020

An important function of renal epithelial cells is the reabsorption of volume, Na+ and bicarbonate (HCO3) from the filtrate. About 85% of the filtrate’s HCO3−  − and 70% of the Na+ are being reabsorbed in the proximal tubule segment of the nephron. As a result, these cells are being continuously subject to large fluxes of Na+ and base through the cell. Renal medullary cells, for instance, are being subject to large fluctuations in osmolality of the extracellular fluid. Transient imbalances in fluid, base and Na+ flow through the cell can cause substantial alterations in cellular volume, pH and electrolytes.

The regulation of transepithelial transport on one hand and of cellular volume-, pH- and electrolyte-homeostasis on the other hand, is of a major physiological interest. Angiotensin II (Ang II) is a powerful regulator of Na+and HCO3  − transport in the proximal tubule. The involvement of ion channels and electrogenic transporters in cellular homeostasis, has been studied by many laboratories using conventional elecrophysiological techniques to measure the resulting changes in membrane potential and ionic currents.
Recent Developments in Confocal Raman Microprobing and Imaging Techniques
Authors: Paul Dhamelincourt
Published: July 2020

This communication presents a summary of the most recent developments in microRaman instrumentation - point analysis and imaging techniques- including the use of confocal optics and line illumination, as now available in certain commercial instruments.

The major development in micro-Raman spectroscopic instrumentation during the last few years is based on the extension of the principles of confocal microscopy. Applied to Raman microprobing the confocal technique provides an efficient way to obtain interference-free Raman spectra, as well as two-or three-dimensional, selective images of small specimens embedded within strong scatterers or fluorescent transparent media. As it is well known, the confocal configuration benefits from the use of spatial filtering by optically conjugated pinhole diaphragms. Such a system isolates the light originating from a small region of the sample coincident with the diffraction-limited, focused laser spot, and efficiently eliminates the contributions from out-of-focus zones.

A new concept of Raman imaging that benefits from the advantages of confocal microscopy has been developed in this laboratory.
Confocal Raman Microscopy of Chromosomes, Cells and Eye-Lenses
Authors: Greve J , Sijtsema NM , de Grauw CJ , Duindam H , Wouters S , Otto C , Vrensen GJ
Published: July 2020

A confocal scanning Raman microscope was constructed for spectroscopy and microscopy of biological samples (Fig. 1). The microscope contains an illumination system in which a focused krypton laser beam, of which the 647.1 nm line is used to reduce damage, is scanned over the sample using a scanning mirror which moves around two orthogonal axes. Raman scattered light is collected by a water immersion objective which directs the light on the scanning mirror. Spectral analysis takes place in a monochromator with two exit ports: one for spectroscopical purposes the other one for imaging. An image is made by scanning the light, present in the Raman band passed by the monochromator, over a CCD using a second scanning mirror which moves synchronously with the first mirror. The spatial resolution is of the order of 0.3 × 0.3 × 1.2 μm3 (x,y,z).

With this microscope we studied the following samples:
Robust Fiber-Optic Coupled Confocal Raman Microscopy for Research and Quality Control Applications
Authors: Pelletier MJ , Slater J , Davis KL , Kowalchyk WK , Lewis IR
Published: July 2020

In this paper we report the continuing development of a novel fiber-optic coupled confocal Raman microscope which can offer spectral resolutions up to 0.6 cm−1 per pixel, spatial resolutions of 1 micron or less with axial resolutions of 2-3 microns. The system is based around a compact base unit which comprises a compact solid-state laser, a proprietary f/1.8 imaging spectrograph, and a TE-cooled CCD detector operating at −70°C.

In Figure 1 a schematic of the fiber coupled microscope is shown. The microscope includes a integrated holographic filter module to prevent silica Raman generated in the excitation fiber from reaching the sample and to reject radiation at the excitation wavelength from being returned to the spectrograph via the collection fiber(s). The architecture has been designed to allow both fluorescence imaging and Raman microspectroscopy to be accomplished without removing the sample. The figure also depicts the positions of linear polarizers which can be used to collect polarized Raman spectra from small particles or thin polymer laminate samples.
Different Mapping Algorithms for the Analysis of Exfoliated Cervical Cells by Infrared Microscopy
Authors: Lowry SR , Smith MJ , Leimer BA
Published: July 2020

The Papanicolaou (Pap) smear is the technique used to screen for abnormalities in cervical cells that may be related to cervical cancer and other problems. A number of research groups have reported results that indicate the infrared or NIR spectroscopy can be used to differentiate between samples of normal cervical cells and abnormal cells.

In this paper we will describe studies performed on cervical cell samples with an infrared microscope and a motorized x-y stage. This configuration allowed us to “Map” the sample in 100 micron increments, where an infrared spectrum is acquired at each point. This integrated system also allowed chemometric algorithms developed with the Nicolet TQ Analyst software to be automatically applied to the spectral data. Samples of cervical cells were obtained from patients using the standard procedure. Part of the sample was used to prepare the Pap smear slide and the remainder was placed in a saline solution and centrifuged for several minutes. The cell suspension was then applied to a Barium Fluoride 5mm X 5mm window and dried.
Near-infrared Imaging in Stroke Research
Authors: Dempsey RJ , Buice RG , Symons WC , Lodder RA
Published: July 2020

Accurate and nondestructive measurement of different lipoproteins simultaneously in carotid plaque in stroke patients using near-infrared (IR) imaging spectrometry seems possible for research. The lipoprotein composition of the plaque appears to have an impact on the outcome of the disease process. Carotid atherosclerosis without associated thrombosis is frequently a benign disease that is asymptomatic, although TIAs may be present in other cases. Many patients with carotid atherosclerosis can be treated surgically by endarterectomy with high initial success and favorable long-term prognosis. The acute manifestation of carotid atherosclerosis - stroke - arises when thrombus or ulceration develop. This potentially life-threatening complication probably develops at the site of plaque fissure or rupture. Recent research by others indicates that it is not the severity of stenosis (plaque volume) that determines the outcome: it is the type of stenosis (plaque chemical composition) and the extent of collateral growth.
Characterization of Keratin Pearls in Oral Squamous Cell Carcinoma Using FT-IR Microspectroscopy
Authors: Schultz CP , Liu K-Z , Kerr PD , Mantsch HH
Published: July 2020

Oral squamous cell carcinoma (SCC) positive biopsies from patients who underwent excision procedures by micrographical surgery were analyzed by FT-IR microspectroscopy in order to examine a specific fine structure of abnormal epithelial growth - the so-called keratin pearls. Taken from the oral cavity of 15 SCC positive patients, all biopsies indicated poorly or well-differentiated cancer containing smaller and larger pearls. In some cases only a few pearls were present; in others many of various sizes.

After surgery the biopsies were rapidly frozen in liquid nitrogen and stored at -80°C before thin sectioning the tissue for infrared measurements. The frozen tissue was then sliced into 8 μm thin sections and dried on an infrared-transparent Bal2window. For comparison one slice of tissue was always used for hematoxylin and eosin staining by drying it on a standard microscope slide. This procedure creates a series of thin sections on BaF2 and glass following an alternate pattern of one 8 μm section for IR microspectroscopy and the next 8 μm one for microscopy.
Infrared Microscopic Imaging of the Diffusion of Liquid Crystals into Thermoplastics
Authors: Wall Bentley G , Snively Chris M , Koenig Jack L
Published: July 2020

Thermoplastic polymer/liquid crystal systems have found application in the generation of display devices known as thermoplastic, polymer dispersed liquid crystals (PDLCs). These systems take advantage of the beneficial properties of both components to generate a device that has unique optical properties. The liquid crystal is dielectric and responds to an electric field. The polymer confines the liquid crystal so that the cells are closed. The two components are melted together until they are miscible. At lower temperatures, the two components phase separate. The liquid crystal component is the minor phase and takes the form of many tiny droplets contained within the major-phase, polymer matrix. An application of an electric field across these systems causes the liquid crystal within the droplets to align with the field. The systems are engineered such that when this alignment occurs there is no refractive index difference between the liquid crystal in the droplets and the polymer matrix, thus, the cells appear optically transparent. When there is no field applied, the liquid crystals in each droplet are aligned without respect to a general direction according to the surface energetics of each droplet/polymer interface. When this is the case, there is a refractive index mismatch between the droplets and the polymer and the cells are opaque. Research of these systems is aimed at improving the optical properties in order to facilitate the manufacturing of improved devices utilizing this technology. Because these systems are generated by a diffusion-controlled, phase separation process, understanding the relevant parameters, particularly the diffusion coefficients, should enable the manufacturing processes of these systems to be controlled more efficiently, generating improved optical properties.
Micro-Raman Spectroscopy for the Characterization of Materials in Electronic and Photonic Devices
Authors: D.Tuschel David
Published: July 2020

Materials characterization is the primary application of macro- and micro-Raman spectroscopy in our laboratory. Specifically, we wish to correlate chemical bonding and short to long range translational symmetry (including amorphous, highly oriented, polycrystalline, and single crystal materials) to physical, optical and electronic properties of materials and devices. Raman spectroscopy is particularly useful in this capacity because of its origin in the vibrational motions of chemically bonded atoms and its dependence upon crystal symmetry through the polarization selection rules. Furthermore, the high spatial resolution and non-destructive nature of micro-Raman spectroscopy make it ideal for in situcharacterization of electronic and photonic devices. We will present results of materials characterization studies, performed using macro- and micro-Raman spectroscopy, of electronic and photonic devices. In addition, we will discuss how the Raman polarization selection rules can be advantageously applied to device characterization.

A primary area of investigation involves the study of ion-implanted and annealed Si by Raman spectroscopy.
“Mute Witnesses, Sure and Faithful”: Microscopic Analysis of Textile Fibers in Criminal Cases
Authors: Houck MM
Published: July 2020

Placing the suspect at the crime scene is an important element in the solution of a crime. A way to do this is to find textile fibers like those from the victim’s environment or the crime scene on the clothing of the suspect. Another way would be to discover fibers like the suspect’s clothing or environment on the victim or at the crime scene. When fibers exhibiting the same microscopic characteristics and optical properties are found in common between a known source and the suspect or victim, an evidentiary value is placed on that association. This value is dependent on many factors that include the type(s) of fibers found (natural or synthetic), the color (s) of the fibers, number of fibers found, the location of fibers on a victim, suspect and/or crime scene and the number of different fibers that “match,” especially if different fibers from the same item of clothing or fibers from more than one item of clothing are found.
Visualizing Molecular Species Within Inorganics: Raman Chemical Imaging of Minerals, Meteorites and Actinides
Authors: Kline Nicole J , Sparrow Mark C , Treado Patrick J
Published: July 2020

Raman chemical imaging microscopy is a powerful technique for the characterization of a wide host of materials, including inorganic species. The technique makes use of a liquid crystal tunable filter (LCTF) imaging spectrometer that is integrated within an infinity-corrected optical microscope. The imaging system provides the performance of a dispersive Raman spectrometer at every pixel of the charge-coupled device (CCD) detector used to capture the Raman image.

We are currently applying Raman microscopy to the chemical imaging analysis of mineral composition and phase chemistry found in meteorites and terrestrial minerals. Determination of the chemical composition and structure of mineral components is often useful in developing an understanding of the petrologic process that formed the minerals, including those minerals that have been exposed to water. This is of particular interest in light of recent promising evidence of past life in Martian meteorites.
FT-IR Spectroscopic Imaging in the Infrared “Fingerprint”Region Using an Mct Array Detector
Authors: Crocombe R A , Wright N , Drapcho DL , McCarthy WJ , Bhandare P , Jiang EJ
Published: July 2020

A new infrared spectroscopic imaging technique has been described, combining step-scan Fourier transform (FT) Michelson interferometry with indium antimonide (InSb) focal-plane array (FPA) image detection [1-3], for use in the range 3950-1975 cm−1. The coupling of such detector to an interferometer provides an optimized method for infrared spectroscopic imaging by simultaneously realizing both a multiplex and multichannel advantage. Specifically, the multiple detector elements enable spectra at all pixels to be collected simultaneously, while the interferometer allows all the spectral frequencies to be measured concurrently. This technique can rapidly generate very high quality, chemically specific images from a wide variety of samples. Preliminary results from the use of a mid-infrared liquid-helium-cooled arsenic-doped-silicon array have also been reported recently [4]. Focal-plane arrays using mercury-cadmium-telluride (MCT) are now commercially available, giving access to the range 3950-800 cm−1, and greatly broadening the applicability of this technique [5].

FT-IR microscopy does not require exotic sample preparation -- samples can be examined in transmission and reflectance, do not need to be stained or coated, and a vacuum is not required.
Multivariate Visualiztion and Analysis Tools for Segmentation and Classification of Vibrational Spectroscopic Images
Authors: Delaglio F , Kidder LH , Levin IW , Lewis EN
Published: July 2020

Vibrational spectroscopic imaging has already demonstrated enormous potential for studying a variety of chemical and biological systems at both the microscopic and macroscopic level. However, these spectral images are large and complicated, typically consisting of tens of thousands of pixels, each with an associated high-resolution vibrational spectrum, leading to data sizes upwards of 64 megabytes. In order to realize the full potential of these spectral images, we must find ways to query the data so that specific questions can be answered.

We illustrate a multivariate approach to this challenge, where each pixel is considered to be a single point in a multivariate (N-dimensional) space. The variables (coordinates) of the point in N dimensions are simply the intensities of the N-point spectrum associated with the pixel. In this representation, pixels with similar spectra will tend to cluster together in the multivariate space, since they will have similar coordinates.
Limitations of Sem Characterization of Semiconductors
Authors: Joy David C
Published: July 2020

The field of semiconductor materials and devices represents a unique challenge to microscopy and microanalysis because the standard of excellence is constantly changing. Driven by the imperative of Moore's law (illustrated in figure 1) - which predicts that the density of devices in a chip doubles every three years - the spatial resolution that must be achieved increases by a factor of two every five years. The problem of meeting this demand is further enhanced by the widespread sentiment that all e-beam tools used on semiconductors should operate at low beam energies (typically below lkeV). Finally, the increase in device packing density and the expected move to 30cm. diameter wafers as substrates for fabrication also means that the microscopist will be faced with the challenge of rapidly and reliably finding a given device or feature among the 108 or so similar features which are present.

The first need is to be able to monitor the basic steps of the fabrication process. Given the assumption that by the year 2001 devices will be built on 0.18μm design rules, it will then be necessary to perform critical dimension metrology with a precision of 2 to 3nm (see figure 2).
Electron Backscatter Diffraction In The Sem: Is Electron Diffraction In The Tem Obsolete?
Authors: Michael J R , Schlienger M E , Goehner R P
Published: July 2020

The technique of electron backscatter diffraction (EBSD) in the scanning electron microscope is currently finding a large number of important applications in materials science. The patterns formed through EBSD were first studied over 40 years ago. It has only been in the last 10 years that the technique has really begun to have an impact on the study of materials. The introduction of automatic pattern indexing software has enabled the technique to be used for mapping the orientation of a polycrystalline sample. The more exciting and universally interesting application of the technique has been the identification of micron and sub-micron sized crystalline phases based on their chemistry and crystallography determined by EBSD.

EBSD is obtained by illuminating a highly tilted sample (>45° from horizontal) with a stationary electron beam. Electrons backscattered from the sample may satisfy the condition for channeling and will produce images that contain bands of increased and decreased intensity that are equivalent to electron channeling patterns.
Low Beam Energy X-Ray Micro Analysis: How Useful Is It?
Authors: Newbury Dale E
Published: July 2020

Throughout the history of electron-beam X-ray microanalysis, analysts have made good use of the strong dependence of electron range on incident energy (R ≈ E1,7) to optimize the analytical volume when attacking certain types of problems, such as inclusions in a matrix or layered specimens. The “conventional” energy range for quantitative electron beam X-ray microanalysis can be thought of as beginning at 10 keV and extending to the upper limit of the accelerating potential, typically 30 - 50 keV depending on the instrument. The lower limit of 10 keV is selected because this is the lowest incident beam energy for which there is a satisfactory analytical X-ray peak excited from the K-, L-, or M- shells (in a few cases, two shells are simultaneously excited, e.g., Fe-K and Fe-L) for every element in the Periodic Table that is accessible to X-ray spectrometry, beginning with Be (Ek =116 eV) and extending to the transuranic elements. This criterion is based upon establishing a minimum overvoltage U = E0/Ec > 1.25, which is the practical minimum for useful excitation.
X-Ray Emission of Porous Materials In The Scanning Electron Microscope Computed Using Monte Carlo Simulations
Authors: Gauvin Raynald
Published: July 2020

Conventional quantitative X-ray microanalysis in the scanning electron microscope or in the electron microprobe is valid for specimens of bulk homogeneous composition and with flat and polished surfaces. Quantitative methods, using X-ray microanalysis and Monte Carlo simulations of electron trajectories in solids, have been developed for the chemical analysis of spherical inclusions embedded in a matrix and for multilayered specimens. In this paper, the effect of porosity and of the size of the pores are investigated concerning their effect on X-ray emission using Monte Carlo simulation of electron trajectories in solids since porous materials are of great technological importance.

This new Monte Carlo program uses elastic Mott cross-sections to compute electron trajectories and the Joy & Luo modification of the continuous Bethe law of energy loss and the details are given elsewhere. This program assumes that all the pores are spherical and have the same size.
Parametrization of The Range of Electron At Low Energy (Eo < 10 Kev) Using The Casino Monte Carlo Program
Authors: Hovington Pierre , Drouin Dominique , Gauvin Raynald , Joy David C
Published: July 2020

The range of electrons for a given beam energy and atomic number is one of the most valuable piece of information a microscopist must know before carrying out qualitative and quantitative analysis of heterogeneous samples in a scanning electron microscope (SEM). The frequently used parametrization of Kanaya & Okayama is only « valid » at high energy (EO > 10 keV). However, with the advent of Field Emission Gun SEM (FEGSEM) most of the effort has been toward low energy analysis where no parametrization is available yet. In this paper, the parametrization of the range of electrons at low energy as a function of atomic number and beam energy will be presented for both the backscattered and the internal electrons.

The distribution of the maximum depth reached by 250 k electrons generated by the CASINO Monte Carlo program2 was used to compute the range for 10 elements at 20 energies.
High Precision Multiple Kev X-Ray Analysis: Tests of Ionization Cross Sections and Monte Carlo Algorithms
Authors: Armstrong John T , Newbury D E , Carpenter P K
Published: July 2020

Determination of the variation of absolute and relative electron-excited x-ray production rates as a function of electron beam energy and sample atomic number is necessary for calculation of the "stopping power" atomic number correction and the relative amount of characteristic fluorescence and for development of “standardless” and Monte Carlo algorithms for quantitative x-ray analysis. Critical to the calculation of x-ray production rates is an accurate expression for the inner shell electron ionization cross section. A large number of expressions have been proposed for the relative x-ray production rates (used in the fluorescence correction)1 and for the ionization cross section used in the atomic number correction, and these yield quite different results. In order to evaluate which expressions gave the most accurate results when applied to quantitative x-ray emission measurements, we performed a series of high precision measurements of x-ray intensities as a function of electron beam accelerating potential for a series of pure element and simple oxide, phosphide, sulfide, and chloride standards for 65 elements ranging in Z from C to U
The Use of Collimating X-Ray Optics For Wavelength Dispersive Spectroscopy
Authors: Agnello R , Howard J , McCarthy J , OHara D
Published: July 2020

There has been much interest in the last few years in the technique for focusing x-rays into high intensity spots using tapered glass capillaries or other forms of grazing incident x-ray reflectors. The resulting microbeams have been used in applications that include microfluorescence, microdiffraction, tomography and lithography. Instead of focusing x-rays to a spot, a collimating optic can be used to capture x-rays from a point source and turn them into a collimated parallel beam at the exit aperture to the optic. Kirkland et. al. have pointed out that the use of such an optic could provide enhanced detection sensitivity in wavelength dispersive spectroscopy.

We have developed a grazing incidence collimating x-ray optic that can be coupled to a simple wavelength dispersive spectrometer (WDS). This combined instrument was designed to enhance the intensity of x-rays from a sample by an order of magnitude or more in the energy range of 0 to 1 keV compared to a conventional WDS.