bluuebunny/crossref_metadata_2025 huggingface dataset:
Raman analysis of microcircuits with lead zirconate titanate (PZT) films
Authors: Tallant D. R. , Schwartz R. W. , Tuttle B. A. , Everist S. C. , Tafoya B. C.
Published: June 2020

Certain compositions and structural forms of lead zirconate titanate (PZT) materials have potential applications in microelectronics because of their ferroelectric properties. One such application is in the development of new types of non-volatile memories. PZT films are integrated into microcircuit components using sol-gel deposition techniques. The solution chemistry effects attendant to different sol-gel preparation procedures have been investigated by several researchers.

We have used Raman spectroscopy both to characterize the metallo-organic species initially laid down on macroscopic platinum substrates during sol-gel processing and to follow the evolution of Pb-Zr-Ti oxide species through high temperature processing. The high temperature processing removes residual organics and creates Pb-Zr-Ti oxide structures that have ferroelectric properties. Low temperature pyrochlore structures, which are not ferroelectric, can be distinguished by Raman spectroscopy from tetragonal and pseudo-cubic/rhombohedral perovskite structures, which are usefully ferroelectric (Top Figure). In addition Raman spectroscopy has identified lead and titanium oxides that form as intermediates in the high temperature crystallization of ferroelectric PZT structures.
Microchemistry of ZnO Varistors
Authors: Soni K. K. , Hwang J. , Dravid V. P. , Mason T. O. , Levi-Setti R.
Published: June 2020

ZnO varistors are made by mixing semiconducting ZnO powder with powders of other metal oxides e.g. Bi2O3, Sb2O3, CoO, MnO2, NiO, Cr2O3, SiO2 etc., followed by conventional pressing and sintering. The non-linear I-V characteristics of ZnO varistors result from the unique properties that the grain boundaries acquire as a result of dopant distribution. Each dopant plays important and sometimes multiple roles in improving the properties. However, the chemical nature of interfaces in this material is formidable mainly because often trace amounts of dopants are involved. A knowledge of the interface microchemistry is an essential component in the ‘grain boundary engineering’ of materials. The most important ingredient in this varistor is Bi2O3 which envelopes the ZnO grains and imparts high resistance to the grain boundaries. The solubility of Bi in ZnO is very small but has not been experimentally determined as a function of temperature.

In this study, the dopant distribution in a commercial ZnO varistor was characterized by a scanning ion microprobe (SIM) developed at The University of Chicago (UC) which offers adequate sensitivity and spatial resolution.
Analysis of philadelphia aerosol
Authors: Wight Scott
Published: June 2020

Size distributions and compositions of atmospheric aerosol are important since they affect such processes as pollutant deposition, visibility reduction, human health, smog formation, and chemical reactions in the atmosphere. Natural and anthropogenic high-temperature combustion sources discharge an abundance of fine particulate material, often with the majority of the mass in the sub-micrometer sized particles. The sub-micrometer particle range is of special interest for source identification because the larger particles are efficiently trapped by the particulate control devices, and the sub-micrometer aerosol exhibits longer residence times in the atmosphere. Insight into the contributing sources to an aerosol population can be gained by investigating the morphology and elemental composition of particles as a function of size.

The Philadelphia area is a highly industrialized urban airshed with many discrete sources of aerosol. Philadelphia atmospheric particulate material has been previously characterized with a dichotomous sampler, which produced only two size fractions with a size cutoff at 2.5 μm.
Development of a standard reference material for analysis of asbestos on filters by TEM
Authors: Turner S. , Steel E.B. , Phelps J.M. , Windsor E.S. , Doorn S.S. , Leigh S.D.
Published: June 2020

Over one-hundred and fifty TEM laboratories in the U.S. are presently involved in the analysis of air, water or other fluids to determine the presence and concentration of asbestos. The analysis by transmission electron microscopy is not automated and requires an analyst to detect and identify particles. Evaluation of the analyst’s performance and assessment of the accuracy of the analyses are important objectives in quality assurance. One method of calibration is to analyze materials that have a known concentration of asbestos particles. The National Institute of Standards and Technology has provided Standard Reference Materials (SRMs) for such analyses. Previous SRMs for TEM analysis of asbestos on filters were comprised of chrysotile deposited from a liquid-based suspension. The development of a new SRM in which asbestos particles were deposited from air is described in the current work.

Chrysotile asbestos fibers were deposited simultaneously onto an array of 320 mixed-cellulose-ester filters by use of an aerosol generator at the Stanford Research Institute.
Quantitative analyses of total carbon in interplanetary dust particles
Authors: Keller L. P. , Thomas K. L. , Bradley J. P. , Brownlee D. E.
Published: June 2020

Interplanetary dust particles (IDPs) collected in the stratosphere are believed to be derived from comets and asteroids. The abundance and chemical state of carbon in IDPs are of particular importance because they provide insight into the processes that have affected carbon from its nucleosynthesis to its incorporation into primitive solar system bodies. Sources of carbon in IDPs may include primary circumstellar condensates (e.g. SiC and graphitic carbons), organic phases derived from the interstellar medium (e.g. polycyclic aromatic hydrocarbons and other residues from radiation-processed ices), biproducts of gas/grain reactions in the solar nebula (e.g. aliphatic hydrocarbons and FeNi carbides), and secondary minerals formed during post-accretional parent body metamorphism (e.g. carbonates). Analysis of carbon in IDPs is complicated by small sample size, loss of volatile components from IDPs during atmospheric entry heating, and terrestrial contamination. The dominant form of carbon observed in IDPs is poorly-crystalline to amorphous material that may be compositionally similar to kerogen.
The kumakhov lens: Prospects for x-ray microanalysis
Authors: Gibson Walter M. , Kumakhov Muridan A.
Published: June 2020

A new optical system based on multiple reflection of X-rays and neutrons along specially shaped solid surfaces first proposed by Kumakhov has undergone intense and rapid development in the USSR and more recently in a joint development effort between the Institute for Roentgen Optical Systems (IROS) in Moscow, Russia, and the Center for X-Ray Optics (CXO) in Albany, NY. The most used X-ray Optical System (XOS) utilizes thin hollow microcapillary tubes arranged appropriately to capture X-rays from a divergent source to produce a quasiparallel beam or a focussed beam as shown schematically in Figure 1. Alternatively, a parallel beam of X-rays (or neutrons) can be deflected or focused. It is also possible to use such systems for energy filtering or energy selection.

The first such systems were constructed from single hollow capillaries and showed that X-rays could indeed be captured and focussed as shown in Figure 2. These "first generation" Kumakhov optics are most efficient for relatively low energy X-rays (0.5-2 keV).
Developing a focused neutron probe for materials analysis
Authors: Mildner D.F.R. , Chen H. , Downing R.G. , Sharov V.A.
Published: June 2020

Long wavelength neutrons have optical properties analogous to those of photons, and may be focused to produce significantly higher fluxes using the principle of multiple mirror reflection from smooth surfaces at small grazing incident angles. Narrowly focused beams of cold neutrons (with wavelengths greater than 0.4 nm) allow greater spatial resolution for analytical applications than previously available, and will improve the detection limits of neutron absorption measurements (which are dependent on the neutron capture reaction rate) for quantitative analysis. Since the absorption cross section increases linearly with neutron wavelength, the reaction rate for a given isotope increases with the use of cold neutrons. This suggests microprobe capabilities which complement other radiation techniques for multidimensional microanalysis of trace elements in materials science. Among the techniques which will benefit by the development of focused neutrons are prompt gamma activation analysis and neutron depth profiling, by increasing the elemental sensitivity, lowering the detection limits, enhancing multi elemental as well as spatial analysis.
DXS: Differential absorption x-ray spectroscopy
Authors: Fisher Robert M.
Published: June 2020

X-ray spectrochemical analysis, with either energy-dispersive (EDS) or wavelength-dispersive (WDS) systems, is is used extensively by electron microscopists to determine the chemical composition of selected features in a wide variety of specimens. Several decades of development have yielded efficient and rugged detector crystals and goniometer hardware as well as sophisticated, but user-friendly, software for quantitative chemical and image analysis. Nevertheless an alternative system, based on differential x-ray absorption with "balanced" transmission filters (DXS™) has attractive advantages as a simple, low cost, system for qualitative x-ray microanalysis which does not require liquid nitrogen. Computer processing of intensities obviates the former need for impossibly-precise adjustment of filter thickness. However the filter array must be preset for analysis of the elements that are believed to be present for routine work.

DXS analysis is based on the abrupt change in x-ray absorption that occurs between particular elements. This is illustrated by the different mass absorption coefficients for Fe and Cr K radiation for a series of filters in increasing atomic number from Ti to Co as shown in Figure 1 (1,2).
Direct observation of nucleation, cluster growth, and structure of solvent-free crystalline C60 and C70
Authors: Yao Nan , Disko M. M. , Sherwood R. D. , Behal S. K. , Cox D. M.
Published: June 2020

C60 and its functionalized derivatives have attracted wide interest due to a great potential for various applications. The C60 molecule has icosahedral symmetry, and nearly spherical shape. Crystalline C60 is a van der Waals bonded molecular crystal with a structure characteristic of cubic close-packed pseudospheres. Its crystal lattice is face-centered-cubic with Fm(-3)m symmetry at ambient temperature and becomes a simple-cubic structure below -18°C with a symmetry of Pa(-3) through a first order transition, C70 is the next-larger fullerene with an elongated “rugby-ball” shape. Its crystal lattice is an fee structure at ambient temperature with many properties similar to those of C60. In this paper we describe our electron microscopy studies of nucleation, cluster growth and structure of pure C60 and C70 crystallites formed on various substrates.
Comprehensive multilayer film analysis with XPS, AES, and EDS
Authors: Miller N. C.
Published: June 2020

Wavelength and energy dispersive x-ray spectroscopy (WDS and EDS) are routinely utilized to measure qualitatively and quantitatively the composition of microscopic features/phases of thickness 0.5 (μm or greater in solids. Surface spectroscopies, especially x-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES), are employed to determine surface chemistry and surface composition respectively of microscopic features 0.2-5 nm thick. The combined utilization of AES and EDS (or WDS) permits microanalysis of surface and subsurface features/phases. Two areas of improved analysis through combined utilization of AES and EDS are imaging/elemental mapping and measurement of vertical diffusion profiles. Strengths of XPS in complementing EDS/WDS will also be discussed.

High resolution surface elemental or chemical mapping can be carried out with scanning Auger or secondary ion mass spectrometry (SIMS) microanalysis, respectively. In fact, both offer improved spacial resolution over WDS and EDS elemental x-ray dot mapping. Using sample rotation while removing material by ion beam sputter etching, three dimensional mapping can be carried out by either surface analysis technique, permitting microanalysis of buried features even in complex heterostructures.
Measurement of the Inelastic Mean Free Path by EELS Analyses of Submicron Spheres
Authors: Bonney Laura A.
Published: June 2020

Accurate measurement of sample thickness is important for analytical electron microscopy (AEM) but is often difficult and tedious. Unlike other thickness measurement methods, with electron energy loss spectroscopy (EELS) thickness may be measured in both amorphous and crystalline specimens and at the same location and orientation at which other data is collected in the electron microscope. Thickness values may be obtained from convergent-beam electron diffraction (CBED) data only if the sample is crystalline with large grains of uniform thickness. Sample thickness may be measured from crystal defects projected through the entire foil, but such defects are not always conveniently located in the area of interest. The distance between contamination spots on the upper and lower surfaces of the specimen may be measured, but this is not considered accurate and contamination is not desirable in microanalysis.

Sample thickness t may be determined with EELS by the relation:

(1)

where It is the total intensity in the EEL spectrum, Iz is the intensity in the zero loss peak, and λ is the inelastic mean free path for energy loss of an incident electron in the sample.
Parallel Detection of Electron Energy Loss Spectra in Direct Mode
Authors: Quandt Eckhard , laBarré Stephan , Hartmann Andreas , Niedrig Heinz
Published: June 2020

Due to the development of semiconductor detectors with high spatial resolution -- e.g. charge coupled devices (CCDs) or photodiode arrays (PDAs) -- the parallel detection of electron energy loss spectra (EELS) has become an important alternative to serial registration. Using parallel detection for recording of energy spectroscopic large angle convergent beam patterns (LACBPs) special selected scattering vectors and small detection apertures lead to very low intensities. Therefore the very sensitive direct irradiation of a cooled linear PDA instead of the common combination of scintillator, fibre optic, and semiconductor has been investigated. In order to obtain a sufficient energy resolution the spectra are optionally magnified by a quadrupole-lens system.

The detector used is a Hamamatsu S2304-512Q linear PDA with 512 diodes and removed quartz-glas window. The sensor size is 13 μm ∗ 2.5 mm with an element spacing of 25 μm. Along with the dispersion of 3.5 μm/eV at 40 keV the maximum energy resolution is limited to about 7 eV, so that a magnification system should be attached for experiments requiring a better resolution.
Time Course of Total Myofibrillar Calcium During the Cardiac Cycle: X-RAY Microprobe Analysis of Voltage-Clamped Guinea-Pig Ventricular Myocytes
Authors: Wendt-Gallitelli Maria Fiora , Isenberg Gerrit
Published: June 2020

We report methodological efforts and results in measuring the changes in total myofibrillar Ca-concentration during systole and diastole. The measurements were made by means of electron microprobe analysis (EPMA) from ultrathin cryosections. We believe that EPMA is the only method that can adequately measure total [Ca] at the place of interest, in this case at the overlapping myofilaments of the A-band. In combination with cryotechniques, it it can be used to assess total [Ca] without disturbing the original in vivo Ca-gradients.

EPMA was performed on isolated ventricular myocytes. The cells were studied at 36 °C and 2 mM extracellular Ca using a whole-cell voltage clamp. Together with the membrane currents, contractions were recorded as unloaded shortening. In a different population of myocytes, Ca ionized in the cytosol ([Ca2+]c) was estimated by microspectrofluometry (50 μM Indo-1, sodium-salt, applied through the patch pipette). The voltage-clamp gave the opportunity of controlling the voltage-operated Ca-influx, and in turn Ca-induced release of Ca from the sarcoplasmic reticulum (SR), and thus the amount of contraction.
High-resolution biological microanalysis in the field-emission STEM
Authors: Leapman R.D. , Andrews S.B.
Published: June 2020

The recent availability of a cryotransfer stage, efficient electron energy loss spectrometers (EELS), and ultrathin window energy-dispersive x-ray spectrometers (EDXS) for the VG Microscopes HB501 field-emission STEM now provides this instrument with the potential for high resolution (<20 nm) biological microanalysis. In practice, limits are normally imposed by the sample itself, due to damage in the electron beam and to changes in structure and composition during freezing, sectioning, transfering and freeze-drying. We have therefore investigated what types of useful high-resolution analytical information can be obtained from rapidly frozen samples, including thin tissue cryosections and frozen isolated macromolecules and macromolecular assemblies.

Frozen-hydrated samples were cryotransfered at ~-175C into the VG STEM after which a vacuum of ~3x10-9 mbar was maintained. Samples were freeze-dried by warming to ~-90C over 30 min and were then recooled to below ~-160C to minimize radiation damage and contamination during analysis. Digital annular dark-field images were obtained at low dose (~10 e/Å2) with single electron sensitivity, using a probe current of 2 to10 pA and a beam energy of 100 keV.
X-ray microanalysis of ion distributions in rye leaf cells at sub-zero temperatures
Authors: Pihakaski-Maunsbach Kaarina , Harvey Diana M.R.
Published: June 2020

X-ray microanalysis has been used in a new application to study potassium changes induced by cold acclimation and freezing injuries in plant cells. Potassium is a key ion since it is the major free cation present in the plant cytoplasm. Most studies dealing with freezing injuries have been conducted on whole plants or pieces of tissues thawn after freezing. Rapid freezing of tissue pieces from defined temperatures, followed by freeze-substitution and analysis of ions by X-ray microanalysis from different cell organelles, allows conclusions about the temperature at which damage occurs.

Seeds of winter rye (Secale cereale L. cv Voima) were germinated in vermiculite at 25 °C for 3 days (non-acclimated, NA). A portion of the seedlings were transferred after 2 days to 5 °C for 4 weeks (cold acclimated, A). Specimens for freeze substitution were taken from the growing temperatures, and from the temperatures where 50% (LT50) and 100% (LT100) of the plants were killed.
Measurement and parameterization of ϕ(ρz) curves for quantitative electron probe microanalysis
Authors: Brown J. D.
Published: June 2020

The goal of correction methods for quantitative electron probe microanalysis is to convert k-ratios for any type of specimen, any x-ray line and all electron beam energies into accurate concentrations. Early attempts to approach this goal were hindered by sparse data on electron interactions with solids, limited knowledge of x-ray parameters such as mass absorption coefficients and limited computing power which made necessary mathematical simplifications in practical applications.

In developing the early models for quantitative analysis, the argument was made that the absorption correction was insensitive to the shape of the ϕ(ρz) curve. For that reason, a number of very crude models which ranged from constant x-ray generation as a function of depth(l) to an exponential decrease from the surface(2) were used. In fact, these models worked quite well for the restricted conditions for which they were designed but of course lack accuracy when applied to more general situations.
ϕ(ρz) measurements
The measurement of the fluorescence of Si K x-rays by Au M x-rays
Authors: Small John A. , Wight Scott A. , Myklebust Robert L. , Newbury Dale E.
Published: June 2020

The characteristic fluorescence correction is used in electron probe microanalysis to account for the x-ray intensity excited in element “a” by the x-rays from the characteristic line of another element, “b”, in the sample. Since the excited intensity is not generated by the primary electron beam, it is necessary to apply the fluorescence correction for quantitative elemental analysis. This correction can be significant particularly when element “b” is a major component of the sample and the characteristic line for element “b” is slightly higher in energy than the critical excitation energy for the excited line of element “a”.

The fluorescence correction, which is used in the various analytical programs, is described in equation 1.

where I'*fa/I'*pa is the ratio of the emitted “a” intensity excited by “b” x-rays to the emitted intensity excited by the primary electron beam. The various parameters in this equation are accurately known for the K x-ray lines, but only very limited information is available for the M x-ray lines.
Problems in electron microprobe analysis of the lanthanides: The x-ray lines
Authors: Hlava P. F.
Published: June 2020

Electron microprobe analysis of materials that contain the lanthanide series of rare earth elements (REE) in natural abundance ratios presents a difficult and truly unique set of problems due to the their chemical and crystallographic similarity and the complexity of the L-spectra used for analysis. REEs differ from one another by the number of protons in their nuclei and the number of electrons in their second inner shell. There are two series of REEs - the lanthanides, from atomic number 58 through 71 and the actinides from 90 through 103. By convention, when most workers speak of the REEs they refer to the lanthanides plus lanthanum, often yttrium and rarely scandium (because these elements are geochemically associated with the lanthanides proper). The terms REE and lanthanide, when used in this paper, will refer to elements of atomic number 57 through 71. In all of these elements the two outer shells, where the valence electrons reside, are essentially identical resulting in chemical behavior that is also essentially identical.
A robust method for determining the Duane-Hunt energy limit from EDS
Authors: Myklebust Robert L. , Fiori Charles E. , Newbury Dale E.
Published: June 2020

The electron beam energy is a parameter required for quantitative electron probe microanalysis. In fact, it occurs in all parts of the ZAF type matrix correction procedure as well as in all of the other matrix correction procedures. Recently, there has been much interest in analyzing materials using lower beam voltages. Since the correction procedures use the so called “overvoltage” term (beam energy/excitation energy), uncertainties in the beam voltage will generate larger errors than when high beam voltages are used. The user may well be faced with an instrument that does not have a very precise voltmeter to measure the beam voltage, or the reported voltage may not actually represent the potential drop from the filament to ground (specimen). The true beam energy may differ from the “measured” potential drop by several hundred volts.

It is difficult and potentially exciting to measure the beam voltage with a calibrated voltmeter; however, we have a built-in method available in the energy-dispersive x-ray detector.
From the evaluation of the NIST Standard K-411 to the concept of a model standard in quantitative electron microprobe analysis
Authors: Vincent Yang S. , Wagstaff Jerry H. , McKay Gordon A.
Published: June 2020

The National Institute of Standards and Technology (NIST, formally NBS) offers a wide spectrum of high quality standards. For microanalytical standards, mineral glasses SRM470 (K-411 and K-412) “provide a highly homogeneous material at microscopic spatial resolution”. Other advantages are their availability and stable compositions. At NASA-JSC, standard K-411 was evaluated along with other microprobe standards by the backward-ZAF-calculation method described by Yang and Gordon, in which no real analysis was performed. Instead, our CAMECA MBX electron microprobe was set up collecting standard records covering different elements of different standards. Then, data of the peak intensity of each standard record were converted to the elemental level and were plotted out for comparison (e.g., Figure 1). Three ZAF packages: CAMECA ZAF, CAMECA PAP, and DUST were used for data reductions.

First, we use the NIST certified data for the K-411 composition with the oxygen concentration being calculated stoichiometrically. The results show that Si is obviously under corrected by all three ZAF packages.
Computer-Assisted Wavelength-Dispersive X-Ray Mapping
Authors: Chambers William F. , Doyle Joe H.
Published: June 2020

Elemental x-ray maps frequently provide one of the best ways to display compositional gradients and inhomogeneities in a sample. Two problems consistently plague the effective use of elemental x-ray mapping: Proper exposure and the maintenance of x-ray focus. Solutions applicable to Cameca MBX microprobes have been previously reported. These solutions involved aligning the X-axis of the electron beam raster parallel to the insensitive axis of the analyzing crystal and synchronously scanning the spectrometer with the Y-axis of the electron beam raster to maintain x-ray focus. The ability of the Cameca to set the beam current via an external computer was also utilized.

We have recently needed to duplicate these capabilities on JEOL microprobes. JEOL and MBX instruments differ in three important aspects relating to their x-ray mapping capabilities.. First, although JEOL instruments can read the beam current, they do not have the capability of setting it via an external computer.
FR-IR Molecular Microanalysis System
Authors: Reffner John A. , Wihlborg William T.
Published: June 2020

The IRμs™ is the first fully integrated system for Fourier transform infrared (FT-IR) microscopy. FT-IR microscopy combines light microscopy for morphological examination with infrared spectroscopy for chemical identification of microscopic samples or domains. Because the IRμs system is a new tool for molecular microanalysis, its optical, mechanical and system design are described to illustrate the state of development of molecular microanalysis. Applications of infrared microspectroscopy are reviewed by Messerschmidt and Harthcock.

Infrared spectral analysis of microscopic samples is not a new idea, it dates back to 1949, with the first commercial instrument being offered by Perkin-Elmer Co. Inc. in 1953. These early efforts showed promise but failed the test of practically. It was not until the advances in computer science were applied did infrared microspectroscopy emerge as a useful technique. Microscopes designed as accessories for Fourier transform infrared spectrometers have been commercially available since 1983. These accessory microscopes provide the best means for analytical spectroscopists to analyze microscopic samples, while not interfering with the FT-IR spectrometer’s normal functions.
Hexachlorobenzine Toxicity in the Monkey Ovary: I. Ultrastructure Induced by Low (0.1 Mg/Kg) Dose Exposure
Authors: Singh A. , Friesen D. , Jarrell J. , Villeneuve D. C.
Published: June 2020

Introduction. Hexachlorobenzene (HCB), a persistent and mobile organochlorine pesticide, is known to occur in the environment. The HCB has been shown to be present in human serum and follicular fluid. An objective of the present study was to detect the cytologic effects of HCB on ovarian follicles in a primate model.

Materials and Methods. Eight Cynomolgus monkeys were housed under controlled conditions at the Animal Facility of Health and Welfare, Ottawa. Animals were orally administered gelatin capsules containing HCB mixed with glucose in daily dosages of 0.0 or 0.1 mg/kg body weight for 90 days; the former was the control group. On the menstrual period following completion of dosing, the monkeys underwent an induction cycle of IVF. At necropsy, one ovary from each animal was diced into ca. 2- to 3-mm cubed specimens that were fixed by immersion in 2.5% glutaraldehyde in 0.1 M cacodylate buffer (pH 7.3); specimens were again fixed in 2% osmium tetroxide prepared in the same buffer.
Ultrastructure of Hamster and Rat Lungs After Chronic Inhalation Exposure to Cadmium Compounds
Authors: Thiedemann K.-U. , Lüthe N. , Kreft A. , Abel U. , Heinrich U. , Glaser U.
Published: June 2020

Chronic inhalation exposure to aerosolized CdCl2 increases the incidence of lung tumors in rats. For the present study small numbers of rats and hamsters were derived from the experimental groups of a longterm inhalation study with CdCl2, CdSO4, CdO and CdS. The goal of our LM, SEM and TEM investigations was to collect detailed observations on fibrotic, hyperplastic, and preneoplastic alterations of lung tissue occurring during this experiment.

Immediately after sacrifice, the lungs of the animals were fixed by intratracheal instillation of Karnovsky fixative. Tissue samples were collected from the right middle lobe of the lung. For TEM the samples were postfixed with OSO4 and routine embedded in Epon. For SEM the tissue was CPD dried, mounted on Al-stubs and sputtered with Au.

Exposure to all Cd compounds caused a significant increase in tumor incidence in rats but not in hamsters. In both species a multifocal alveolar bronchiolization and a generalized thickening of the alveolar septa were observed.
Characterisation and Classification of Individual Coal Mine Dust Particles by Computer-Controlled Electron Microprobe Analysis
Authors: Dorriné W. , Van Espen P. , Adams F. , Préat B.
Published: June 2020

Extremely dusty working conditions are a serious health risk for coal miners. Quartz and other minerals are known to cause lung diseases when inhaled over long periods of time. In this work, a study was made of the mineral content in coal mine dust. Individual particles were characterised using computer controlled electron microprobe analysis and then classified into different mineral categories using a multivariate classification procedure.

Coal mine dust particles were collected from the Zolder coal mine, Belgium, using a BAT II cyclone sampling unit. Small quantities of the dust were suspended in n-hexane using an ultrasonic water bath. Approximately 100 μl of the suspension were spotted on a plexiglass stub and dried. The excess carbon was removed by ashing the samples for two hours in a low temperature asher (LTA). The samples were coated with a carbon layer of ±40 nm for microprobe analysis. An identical sample preparation procedure was used to prepare 6 mineral standards : biotite, illite, kaolinite, quartz, muscovite and ripidolite.
Methods to Study Interactions Between Inhaled Substances and Epithelium of the Respiratory Tract in Vitro
Authors: Adler Kenneth B. , Akley Nancy J. , Lee Jianngwu
Published: June 2020

Epithelium lining the tracheobronchial tree represents the first cells with which particulates, gases, microbes, etc., come into contact upon inhalation. Thus, interactions between such inhaled substances and epithelial cells probably are integral to the pathogenesis of several occupational or environmental - related pulmonary lesions, yet such interactions have not yet been elucidated fully. Many published studies have described patterns of deposition within extra- and intrapulmonary airways and alveolar ducts, and histologic and ultrastructural changes in epithelium in vivo in response to inhalation and deposition. However, our knowledge of specific structural and functional responses of airway epithelium on a cellular level is limited, since exposures of animals in vivo or even tissues in situ do not allow for studying intracellular responses, especially subtle sublytic alterations which could be the basis for subsequent pathogenic responses.

For this reason, investigators have utilized cell culture systems to examine intracellular mechanisms related to responses of respiratory epithelium to deleterious substances which may be inhaled in an occupational or environmental setting.
Bulk Specimen Preparation For X-Ray Microanalysis of Plant Cells
Authors: Ahlstrand Gilbert G. , Zeyen Richard J.
Published: June 2020

Numerous plant pathological investigations have been published where pathologists determined elemental differences between diseased and healthy plant tissue using unfractured bulk specimens and energy dispersive x-ray microanalysis (EDX). In these studies effects of specimen preparation procedures were largely ignored (1). Our objective was to compare bulk specimen preparation procedures using healthy leaf epidermal (surface) cells of barley, Hordeum vulgare, (Fig. 1) to determine advantages and disadvantages of each procedure for reference to future pathological work using EDX. Three preparation procedures were compared: 1) Frozen-hydrated (FH) specimens to maintain soluble and insoluble elements in situ; 2) Freeze-dried (FD) specimens to maintain total soluble and insoluble elements and allow deeper beam penetration than does FH, and; 3) Formalin/acetic acid/ethanol (FAA) fixed specimens, dehydrated in ethanol, and critical point dried (CD) using CO2, for determination of elemental loss in liquid fixatives (2,3).

Aluminum specimen stubs were colloidal graphite coated (leaf segments attached to graphite areas) leaving clean Al margins for calibration.
Intergranular Boron Segregation in Nickel-Based Superalloys
Authors: Koopman Mark C. , Thompson Raymond G.
Published: June 2020

Boron has long been known for its beneficial effects on grain boundary toughness at high temperature in stress rupture and more recently at low temperature in Ni3Al. It also has a bad reputation for promoting intergranular microfissuring in the heat affected zone of welds. Although its intergranular segregation behavior is documented for the nickel aluminides, its segregation in high nickel alloys has not been well documented. The present research is directed at exploring the chemistry of intergranular surfaces in an alloy matrix similar to alloy 718 with controlled interstitial and substitutional impurities.

A base composition contained typical alloy 718 levels of Ni, Cr, Fe, Mo, Nb, Al, Ti, and less than 0.001w% of S, B, C, P, Si, Zr, and Hf. Three modifications of this matrix where examined: one with .0.01 B and Hf; one with 0.01 B, C, Hf, and Zr; and one with 0.01 B, S, P, and Zr. Specimens where electrolytically charged with hydrogen to promote intergranular fracture.
Multispectral Surface Analytical Microscopy: A Third-Generation Scanning Auger Electron Microscope
Authors: Prutton M , El Gomati M M , Greenwood J C , Kennyr P G , Barkshire I R , Dee J C
Published: June 2020

The quantitative interpretation of scanning Auger electron microscope (SAM) images has been shown to require the use of multi-spectral imaging of the surface under study. In a multi-spectral analytical microscope (MULSAM) a set of maps (bands) is acquired from the same area of a sample using scattered electrons with different kinetic energies as well as other signals from the sample such as current flowing to ground, the conventional SEM signal and characteristic x-rays. The resulting set of bands is a multi-spectral image which can be processed using models of the electron scattering in the sample and statistical transforms well known in LANDSAT imaging technology. The processed images can separate the mixed effects of topography, surface chemical inhomogeneity and bulk chemical composition fluctuations occurring in the bands of raw data.

A computer controlled, UHV, energy analysing, scanning electron SEM will be described in this paper. The microscope contains facilities for collecting up to 23 256 by 256 pixel image bands from the same area of the sample.
Convergent-Beam RHEED of GaAs(110) in a STEM: Theory and Experiment
Authors: Bleloch A. L. , Howie A. , Lanzerotti M. Y.
Published: June 2020

A number of approaches to the theory of reflection high energy electron diffraction (RHEED) have been published over the years. There have been, however, few direct comparisons with experiment. In particular, the authors are not aware of calculations of the type of convergent beam RHEED (CBRHEED) pattern with very large convergence angle presented here. (By the principle of reciprocity, parallel illumination and a large collection angle in STEM is equivalent to a large angle convergent probe in a conventional transmission electron microscope (CTEM)) Large angle CBRHEED patterns provide a convenient method for investigating the origin and sensitivity of the so called surface resonance lines. These lines are the prominent features marked on Figure 1. There have been a number of attempts to explain this phenomenon. Initial results of calculations on GaAs patterns are presented together with experimental results.

The approach is an extension of that of Collela in that Bloch wave amplitudes in three dimensions are computed with suitable reflection boundary conditions.
Kinematic Approximations in TED and RHEED Analysis of Reconstructed Surfaces
Authors: Peng L. -M. , Whelan M. J.
Published: June 2020

In recent years there has been a trend in the structure determination of reconstructed surfaces to use high energy electron diffraction techniques, and to employ a kinematic approximation in analyzing the intensities of surface superlattice reflections. Experimentally this is motivated by the great success of the determination of the dimer adatom stacking fault (DAS) structure of the Si(111) 7 × 7 reconstructed surface.

While in the case of transmission electron diffraction (TED) the validity of the kinematic approximation has been examined by using multislice calculations for Si and certain incident beam directions, far less has been done in the reflection high energy electron diffraction (RHEED) case. In this paper we aim to provide a thorough Bloch wave analysis of the various diffraction processes involved, and to set criteria on the validity for the kinematic analysis of the intensities of the surface superlattice reflections.

The validity of the kinematic analysis, being common to both the TED and RHEED case, relies primarily on two underlying observations, namely (l)the surface superlattice scattering in the selvedge is kinematically dominating, and (2)the superlattice diffracted beams are uncoupled from the fundamental diffracted beams within the bulk.
Investigation of Beam Energy Threshold and Atom Diffusion Effects in Ionization Damage of Organic Molecular Crystals
Authors: Howie A. , Mohd Muhid M.N. , Valdré U.
Published: June 2020

The electron beam damage cross section σ(E) in thin aromatic molecular crystals has an appearance threshold near lkeV beam energy shown in fig. 1. By contrast no such threshold appears (fig. 2) for damage in sufficiently thin crystals of much more sensitive non-aromatic molecules. We conclude that the usually dominant valence excitation damage mechanism is suppressed by the aromatic π-electron screening, leaving the less probable carbon K-shell ionisation process as the key damage event. Alternative explanations based on critical momentum transfer to whole molecules in these weakly bonded crystals could also give a threshold effect but its position in energy would increase with the mass of the molecule which is contrary to observation.

Quantitative investigation of this hypothesis is complicated by strong scattering and energy loss which can prevent the beam penetrating deeper layers in the crystal with sufficient energy to damage them. The results have therefore been simulated by Monte Carlo methods which explain well the dependence of the damage cross sections on both beam energy and crystal thickness.
Principles and Utilization of the Electron Beam Damage of Synthetic Polymers
Authors: Vesely D.
Published: June 2020

The rapid decomposition of polymeric samples is a major problem in structural investigations of these materials, as the crystallographic information and mass/thickness contrast can be quickly lost. The X-ray elemental analysis can also be affected by loss of elements and often extrapolation to zero exposure is necessary. It is thus of great interest to know how quickly this decomposition occurs for a given polymer.

The beam damage rate can be measured by loss of crystallinity, loss of mass or loss of elements. The measured decay curves can be approximated by a double exponential function for which only three constants are needed. This describes the behaviour of most polymers very well, however an accurate experimental evaluation of these constants is not easy. The most important and difficult parameters to measure are the initial intensity, exposure and size of the irradiated area. It is not clear why the double exponential function is suitable, if it is a chemical law or if it fits purely by coincidence.
Characteristic X-ray Emission from SrTiO3 by Channeling Electrons
Authors: Ohshima Kiyoshi , Endoh Hisamitsu , Shimizu Ryuichi
Published: June 2020

Count rate of characteristic x ray changes with the incident condition of electron beames to a crystal. The phenomena is utilized by ALCHEMI to determine the positin of impurity atoms in unit cell. Ionization of atoms, which causes the emission of characteristic x ray, depends on localization of incident electrons. The present paper shows the relation between count rates of characteristic x ray and incident condition of electron beams.

Experiment was performed by using JEM_4000EX electron microscope with TN-2000 EDX system. Specimen was prepared by cleaving SrTiO3 and observed from 110 direction. As shown in Fig. 1, 1ll-planes consist of two kinds of atomic planes, Sr-plane and Ti-plane, which are arranged alternatively. Figure 2 shows x-ray spectra of SrTiO3 illuminated by 200keV electrons in such an incident condition that 111-systematic reflections were excited, and particulaly in (a) symmetric incidence and in (b) 222-Bragg reflecting condition. Counts, NT i and Ns r, of characteristic x ray excited by Ti and Sr K-shell ionization respectively are obtained by measuring the areas under the corresponding peaks of the spectra.
Practical Importance of Spatial Resolution and Analytical Sensitivity in AEM X-ray Microanalysis
Authors: Zhang J. , Williams D.B. , Goldstein J.I.
Published: June 2020

Analytical sensitivity and spatial resolution are important and closely related factors in x-ray microanalysis using the AEM. Analytical sensitivity is the ability to distinguish, for a given element under given conditions, between two concentrations that are nearly equal. The analytical sensitivity is directly related to the number of x-ray counts collected and, therefore, to the probe current, specimen thickness and counting time. The spatial resolution in AEM analysis is determined by the probe size and beam broadening in the specimen. A finer probe and a thinner specimen give a higher spatial resolution. However, the resulting lower beam current and smaller X-ray excitation volume degrade analytical sensitivity. A compromise must be made between high spatial resolution and an acceptable analytical sensitivity. In this paper, we show the necessity of evaluating these two parameters in order to determine the low temperature Fe-Ni phase diagram.

A Phillips EM400T AEM with an EDAX/TN2000 EDS/MCA system and a VG HB501 FEG STEM with a LINK AN10 EDS/MCA system were used.
Simultaneous Evaluation of Weight Factors and k Factors for Quantitative x-ray Microanalysis of Thin Specimens
Authors: Heng Yew-Meng , Simon Gerard
Published: June 2020

Quantitative analyses of elemental content in thin specimens using X-ray energy dispersive spectroscopy (XEDS) in the TEM are commonly effected by the Cliff-Lorimer elements ratio approach or the Hall’s peak-to-continuum normalization method. The former method is mainly used in metallurgy, while the latter is favoured in biology. These two methods require accurate proportionality factors in order to convert the characteristic X-ray intensities, Ia and Ib, to the concentrations of the elements, Ca and Cb.
Nevertheless, both factors can be related as follows

where Ic is the intensity of a fixed continuum region and Eqn.(3) assumes that the Z2 of the compositions of the two standards are not significantly different.

This study evaluates the accuracy of the WP and Wca which were determined using standards. To accomplish this, these factors were used to determine kPca, which was then compared to that measured from compounds of known stoichiometry, as well as that calculated theoretically.
Spatial Resolution and Detectability Limits in Thin-Film X-ay Microanalysis
Authors: Goldstein J. I. , Lyman C. E. , Zhang J.
Published: June 2020

The major advantage of performing x-ray microanalysis in the analytical electron microscope (AEM) is the high compositional spatial resolution and the chemical analysis sensitivity. The spatial resolution (R) is dependent on the size of the focused electron probe (d) and the amount of electron beam broadening (b). The spatial resolution across a discrete interface is:

The amount of beam broadening is directly proportional to the thickness (t) to the 3/2 power and inversely proportional to the beam voltage (E). Optimizing d and b involve a consideration of the minimum x-ray intensity necessary for analysis since the x-ray intensity is decreased by minimizing d and t. To obtain the optimum spatial resolution one should use the thinnest possible specimen, a high kV AEM and a high brightness field emission gun (FEG). Figure 1 shows a Ni composition profile across a planar lOnm precipitate in the plessite region of the Grant iron meteorite. A spatial resolution of 2.5nm was obtained from a 20nm thick sample analyzed in a VG Microscopes, Ltd. HB 501 FEG AEM (probe diameter 1.8nm (FWTM)).
Application of Parallel Computing to the Monte Carlo Simulation of Electron Scattering in Solids: A Rapid Method for Profile Deconvolution
Authors: Romig A. D. , Plimpton S. J. , Myklebust R. L. , Newbury D. E.
Published: June 2020

X-ray microanalysis by analytical electron microscopy (AEM) has proven to be a powerful tool for characterizing the spatial distribution of solute elements in materials. True compositional variations over spatial scales smaller than the actual resolution for microanalysis can be determined if the measured composition profile is deconvoluted. Explicit deconvolutions of such data, via conventional techniques such as Fourier transforms, are not possible due to statistical noise in AEM microanalytical data. Hence, the method of choice is to accomplish the deconvolution via iterative convolutions. In this method, a function describing the assumed true composition profile, calculated by physically permissible thermodynamic and kinetic modeling, is convoluted with the x-ray generation function and the result compared to the measured composition profile. If the measured and calculated profiles agree within experimental error, it is assumed that the true compositional profile has been determined. If the measured and calculated composition profiles are in disagreement, the assumptions in the physical model are adjusted and the convolution process repeated.