bluuebunny/crossref_metadata_2025 huggingface dataset:
On the applicability of bloch’s theorem to the total wave function in the dynamical theory of electron diffraction
Authors: Kim H. S. , Sheinin S. S.
Published: June 2020

The dynamical theory of electron diffraction is widely used in materials science problems such as determining the contrast in electron microscope images of crystal defects, calculations of structure images and calculations of diffracted beam intensities in electron diffraction patterns. In carrying out these calculations, the high energy approximation is normally made and it is usually assumed that the crystal is in a symmetrical Laue orientation. In practice, however, a specimen in the electron microscope will generally be oriented so that the non-symmetrical Laue case is obtained. Even in those special cases where the symmetrical Laue case is obtained for the zero order Laue zone reflections, non-symmetrical Laue effects may occur if reflections in higher order zones are important. It has been shown in the literature that the Bloch functions are not orthogonal in more general forms of the dynamical theory in which the high energy approximation is not made and the nonsymmetrical Laue case is considered,.
Auger electron spectroscopy at nanometer resolution
Authors: Hembree Gary G.
Published: June 2020

Auger electron spectroscopy (AES) is a surface sensitive microanalytical technique. Auger electrons are only detected from the top few atomic layers due to their very small inelastic mean free paths. The lateral spatial resolution of AES of thin samples is dominated by the excitation beam profile. Thin samples are defined as having a thickness which is much smaller than the back-scattered electron range at the incident beam energy. Utilizing high current density nanometer-sized probes available in field emission gun STEMs, AES signals extracted from sample regions as small as a few atoms should be detectable. However, the extremely low production efficiency for Auger electrons makes this atomic scale resolution difficult to achieve in practice.

We have achieved nanometer spatial resolution AES in our modified Vacuum Generators HB-501S. In this instrument secondary electrons emitted from either surface of the sample are efficiently collected using the collimating properties of the objective lens field, a sample bias potential and additional solenoidal focusing coils.
Recent improvements of the capabilities of multichannel Raman microprobing
Authors: Delhaye M. , Barbillat J. , Dhamelincourt P. ,   DILOR S.A. (France)
Published: June 2020

Raman microprobing techniques, pioneered nearly 20 years ago, have demonstrated their potential in a large variety of application domains. From the origin up to now, a fruitflul collaboration was established between our laboratory at CNRS-University of Lille - and the industrial team of engineers and scientists brought together by E. DA SILVA at DILOR. A series of innovative progresses, inventions and developments was undoubtedly the consequence of this close cooperation, resulting from a careful analysis of the requirements of spectroscopists and analysts in fundamental or applied research, together with a critical appreciation of the various approaches offered by new technologies.

The choice of dispersion, resolution and spectral coverage of conventional optical spectrometers are physically limited by the design parameters (i.e. grating groove spacing, diffraction angle, focal length and detector array dimensions). However, it would be often desirable, in order to select the best compromise of Resonance Raman and fluorescence background, to first examine quickly at low dispersion the whole spectrum from near UV to near IR, in the next step to cover at once the full vibrational range 0-3500 cm-1 with the choosen exciting radiation for a rapid survey of an unknown specimen, and finally to focus the spectral analysis in a narrow spectral domain at high resolution. Such a procedure is often not feasible with a single instrument.
Industrial applications of Raman microscopy
Authors: Gerrard D.L.
Published: June 2020

One of the major advantages of Raman spectroscopy for the industrial analyst is its capability for providing spatially resolved molecular information on a wide range of inorganic materials. Although the technique of Raman microscopy has been available for nearly twenty years its value in industrial analysis is still not widely appreciated. Recent developments in the use of near infrared excitation with Fourier transform spectrometers and of microline focus systems with charge-coupled devices as detectors have greatly expanded the value of the technique and should help it to appeal to a wider audience. Raman microscopy provides much valuable information in its own right and can often be used to solve analytical problems without reference to any other technique. However, it is usually of greatest value to the industrial analyst when used in conjunction with other microspectroscopy techniques such as scanning electron microscopy/energy dispersive X-ray analysis, infrared microscopy, proton-induced X-ray emission, laser ionisation mass analysis and laser scanning optical microscopy.
Resolution in scanning IR infrared microprobe analysis
Authors: Reffner John A.
Published: June 2020

The scanning infrared microprobe was critically analyzed in terms of both its imaging and its compositional resolution. Fundamentally, resolution is the act or process of breaking something into its constituent parts or elements. Separating parts of the image is the point-to-point resolution of an imaging system. In interferometry and profilometry, the separation of heights is an additional criterion for resolution. Microprobe analysis has extended-resolution requirements that consist of the break-up of the sample's image into its chemical parts.

In scanning infrared microprobe analysis, resolution has several meanings: resolution of the visual image, the spatial resolution of the analyzed domain, and the resolution of the chemistry within the analyzed sample. The point-to-point resolution of the visual image is limited by diffraction, as in all classical microscopy. The resolution, in terms of the area defined for spectral analysis, is limited by both diffraction effects and spectrometer sensitivity. The chemical resolution of the SIRM is compared with other microprobe techniques.
The use of IR microspectroscopy in the analysis of etowah textiles: evidence of dye use and pseud0m0rph formation
Authors: Martoglio Pamela A. , Jakes K. A. , Katon J. E.
Published: June 2020

Previously, our laboratory reported the analysis of archaeological textiles from the Paracas Necropolis (400 BC - 400 AD) in Peru. The study has been expanded to include textile fragments from the Etowah Mound C located in Northwest Georgia. These fragments have been dated approximately 1200 AD. Samples were removed from four textile fragments, catalog numbers EMC 640, EMC 842, EMO A842, and an unnumbered copper covered ear disk. These textiles have been described in detail in other publications. Infrared and visible spectra were obtained from fibers removed from each of these fragments, as well as spectra of three dye plant extracts (Galium corymbosium, Galium aparine, Rubia tinctoria or cordifolia) and spectra of alum mordanted wool dyed with those extracts.

IR spectra are obtained on an Analect AQS-20M IR microspectrometer system with an MCT narrow band detector. Single fibers are prepared for analysis by flattening with a metal probe and transferring to a 1 mm-thick KC1 plate. Typical sample areas range from 30 to 50 μm in diameter.
Pressure tuning IR and micro-raman spectra of solid zeiseߣs salt, kp[pt(η-C2H4)Cl4], and the related dimer, [Pt(η-C2H4)Cl2]2
Authors: Baldwin Jean , Butler Ian S. , Gilson Denis F. R.
Published: June 2020

Pressure-tuning vibrational spectroscopy using diamond-anvil cells is now well established as a useful technique for investigating the phase-transition behavior of inorganic and organic solids. Much of our recent research has been focused on organotransition metal compounds, especially metal carbonyls. The pressure dependences (dv/dP) of the v(CO) modes provide important information on the extent of #- backbonding between the metals and the carbonyl groups. We have now extended these high-presure studies to other #-acceptor ligands, including olefins. We report here the results of a high-pressure IR and micro-Raman spectroscopic investigation of the ethylene complexes, K[Pt(η-C2H4)C13] (Zeise's salt) and the related dimeric species, [Pt(η-C2H4)C12]2- We were interested in examining the effect of high pressures on the Dewar-Chatt-Ducanson σ-/π-bonding description of the platinum-ethylene bonding. There is still considerable controversy over the relative σ- and π-contributions to the overall bonding in such metal-olefin complexes.

Micro-Raman spectra of solid K[Pt(η-C2H4)C13] were obtained at room temperature for the low-energy region (500-180 cm-1) at varying pressures up to 33 kbar with the aid of a diamond-anvil cell. Similarly, pressure-tuning IR spectra were measured for Zeise's salt (3080-480 cm-1; 32 kbar) and Zeise's dimer (4000-480 cm-1; 28 kbar) up to the pressures indicated.
Use of Raman microprobe for study of inhomogeneity of the high-transition-temperature superconductors
Authors: Ishitani Akira , Katagiri Gen , Ishida Hideyuki
Published: June 2020

Study of inhomogeneity of high Tc superconductors is becoming more important when real application of the exciting materials has started. Raman microprobe can be one of the important techniques for the characterization because of the capability of giving detailed structural information with μm spatial resolution. Preliminary study on YBa2Cu3Oz(YBCO) will be reported.

Qualitative analysis of impurity phases by Raman spectroscopy is effective, because YBCO has relatively small scattering capability whereas common impurities like Y2BaCuO5 and BaCuO2 show intense Raman scattering as indicated in Figure 1. A fused YBCO with Y2BaCuO5 intentionally brought in to enhance the pinning effect shows clearly the characteristic Y2BaCuO5 spectrum overlapped with the host material as in Figure 2.

Study of crystalline orientation of polycrystal1ine YBCO is important for practical application as an electric wire. The average orientation can be obtained by Xray and neutron diffraction techniques. Raman microprobe gives orientation of a minute crystal of the size of μm range. Figure 3 gives an example.
Energy-filtered imaging of biological specimens
Authors: Bazett-Jones David P.
Published: June 2020

Chromatic aberration in the conventional transmission electron microscope (CTEM) results in a loss in spatial resolution and a decrease in image contrast. The losses in energy of scattered electrons, however, can provide analytical information because of the unique elemental ionization edges or electronic structure information represented in an electron energy loss spectrum. Energy filtered or electron spectroscopic imaging (ESI) can be achieved with an aberration-corrected, electron imaging spectrometer located after the specimen in a CTEM. Images formed with appropriately chosen windows in the energy loss spectrum provide the information to generate elemental distribution maps of the specimen. This laboratory is applying these ESI techniques to the examination of the cell's nuclear components such as chromatin and other nucleic acid-containing molecular complexes. Structural and stoichiometric information relating to protein and nucleic acid interactions can be obtained by phosphorus mapping, an outcome of the generally higher level of phosphorus in nucleic acid over associating proteins.
Parallel-EELS mapping of calcium in cryosectioned cells
Authors: Leapman R.D. , Hunt J.A. , Buchanan R.A. , Andrews S.B.
Published: June 2020

Electron energy loss spectroscopy (EELS) in the scanning transmission electron microscope (STEM) provides a high sensitivity for microanalysis of certain important biological elements whose physiological concentrations in cells are rather low. Minimum detectable concentrations for calcium obtained by EELS can be better than those obtained by energy-dispersive x-ray spectroscopy (EDXS). However, in order to detect the very small core-edge signal/background ratios encountered in EELS of biological specimens, relatively elaborate acquisition and processing methods must be employed. Application of another strategy, STEM-EELS elemental mapping, has generally been restricted to analyses where elements are present at relatively high concentrations, such as calcium in mineralized tissue or carbon, nitrogen and oxygen in organic specimens.This is because only simple methods were available for signal estimation if the data had to be processed on-the-fly. Recently there has been considerable interest in the spectrum-imaging technique where entire spectra are collected at each pixel. In the present work we have applied this technique to measure calcium in Purkinje cell dendrites of rapidly frozen mouse cerebellar cortex.
Energy-filtered imaging in biological intermediate voltage TEM
Authors: Gubbens A.J. , Krivanek O.L.
Published: June 2020

In biological specimens of 150 nm and greater, inelastic scattering typically surpasses elastic scattering in magnitude. Because of the chromatic aberration of the objective lens of a TEM, the inelastically scattered electrons are focused differently, resulting in a loss of contrast in an ordinary TEM. With energy filtering, however, the inelastically scattered electrons can be prevented from contributing to the image, resulting in substantial recovery of contrast. In very thick specimens (1-5 μm), an energy filter can be used to select electrons of a particular energy loss, and an image with usable contrast can be formed. Further, by imaging only with electrons that have experienced characteristic energy losses, information can be obtained about the spatial distribution of various elements in the sample.

Because of presently available instrumentation, energy filtered biological TEM has so far only been performed with TEMs of primary energies of 120 keV and lower. In this paper, we demonstrate the feasibilty of obtaining interesting biological information with a newly developed imaging filter designed for operation at up to 400 kV.
High-resolution backscattered electron images in the scanning electron microscope
Authors: Wells Oliver C. , Cheng P.C.
Published: June 2020

In this discussion the words “high resolution imaging” of a solid sample in the scanning electron microscope (SEM) mean that details can be resolved that are considerably smaller than the penetration depth of the incident electron beam (EB) into the specimen. “Atomic resolution” in either the transmission electron microscope (TEM) or scanning transmission electron microscope (STEM) means that columns of atoms are resolved.

Image contrasts in the backscattered electron (BSE) image are strongly affected by the specimen tilt and by the position and energy sensitivity of the BSE detector. The expression “BSE image” generally implies that the specimen is normal to the beam and the detector is above it. This shows compositional variations in the specimen with a spatial resolution limited by the spreading of the EB during the initial stages of penetration. This is similar in basic principle to the Z-Contrast method in the STEM that shows atomic resolution from a thinned single crystal mounted in the magnetic field of the focusing lens.
The use of L x-ray spectra of the first-series transition elements for quantitative analysis with the electron microprobe
Authors: Rémond G. , Fialin M. , Gilles C.
Published: June 2020

For the first transition-series metals with filled or partly filled 3d shells, the final states of the soft L x-ray emission bands are valence hole states ant their L emission spectra have been intensively used to investigate the valence electronic structure. The possible use of the Lα lines of these elements for quantitative analysis by x-ray spectrometry with the Electron Probe Micro-Analyzer is discussed and illustrated for the case of the Zn Lα emission band analyzed with a TAP monochromator.

As shown in Figure 1 the Zn Lα emission band of pure metallic zinc exhibits an asymmetrical shape resulting from a broad tail occurring on the short wavelength side (high energy side) of the peak. This tail is the envelope of many unresolved closely spaced satellite features which arise from the deexcitation of the L3 vacancy in the presence of multiple outer vacancies. The digitally recorded Zn Lα emission band was processed by adding Gaussian offsets to the pseudo-Voigt profile of the Zn Lα diagram line used as a fitting function.
EPMA of submicron coatings containing ultralight elements
Authors: Willich Peter
Published: June 2020

Materials containing ultralight elements (B, C, N, O) in combination with a metal are of considerable interest in thin film technology. Quantitative electron probe microanalysis of the coatings should be independent of the substrate and has to be carried out under the condition that the ultimate depth of x-ray emission (Rx) is within the provided film thickness of 0.2-0.8 μm. Rx, for an element (critical excitation energy Ec) in a specified matrix is controlled by the energy (E0) of the primary electrons. EPMA of high atomic number elements (Ec = 2-7 keV), under the condition of Rx < 1 μm, frequently requires operation at a low overvoltage of E0/Ec < 2. Consequendy, tne x-ray intensities are very low and the analytical sensitivity is drastically reduced. For the ultralight elements the strong effects oft x-ray absorption always lead to a shallow depth of x-ray emission, even at a high overvoltage.
Layered and ion implantation specimens as possible reference materials for the electron-probe microanalysis
Authors: Remond G. , Packwood R.H. , Gilles C. , Chryssoulis S.
Published: June 2020

Merits and limitations of layered and ion implanted specimens as possible reference materials to calibrate spatially resolved analytical techniques are discussed and illustrated for the case of gold analysis in minerals by means of x-ray spectrometry with the EPMA. To overcome the random heterogeneities of minerals, thin film deposition and ion implantation may offer an original approach to the manufacture of controlled concentration/ distribution reference materials for quantification of trace elements with the same matrix as the unknown.

In order to evaluate the accuracy of data obtained by EPMA we have compared measured and calculated x-ray intensities for homogeneous and heterogeneous specimens. Au Lα and Au Mα x-ray intensities were recorded at various electron beam energies, and hence at various sampling depths, for gold coated and gold implanted specimens. X-ray intensity calculations are based on the use of analytical expressions for both the depth ionization Φ (ρz) and the depth concentration C (ρz) distributions respectively.
Bulk Composition from Electron Beam Excited X-RAY Analysis?
Authors: Herrington Charles R. , Geller Joseph D.
Published: June 2020

Bulk analysis is often accomplished using techniques such as classical wet chemistry, atomic absorption, x-ray fluorescence, inductively coupled plasma, combustion procedures, and optical emission spectroscopy. To use "ZAF" or other programs (which are for electron beam excited x-ray spectra) to convert "k" or intensity ratios to concentration it is required that the electron beam excitation volume be homogeneous. The correction programs calculate atomic number, absorption, and fluorescence factors from the detected x-ray intensity fractions assuming the x-rays are coming from this homogeneous volume. If the specimen is not homogeneous within the excitation volume the program will miscalculate the factors. Often used (but incorrectly applied) methods for analyzing large areas on bulk materials are defocusing of the electron beam and rastering a focussed beam over areas to cover the phases present. The purpose of this study is to demonstrate the dangers of improperly applying these corrections and to demonstrate the alternate technique of using phase area analysis combined with the chemistry and density of each phase to arrive at bulk composition.
Evaluation of particle effects in bremsstrahlung and in quantitative energy-dispersive x-ray microanalysis
Authors: Lu Yun , David C. Joy
Published: June 2020

The magnitude and the spectral form of bremsstrahlung signal contains much information about the target and is significantly influenced by the surface irregularities. By computer modelling, it is possible to extract the information to perform more accurate quantitative x-ray microanalysis for specimens with special geometries. In this research, bremsstrahlung spectra obtained from electron beams striking at selected locations of spherical particles were investigated by Monte Carlo simulations and experimental observations. The effects of surface geometries and the x-ray path lengths in the specimens on the variation of bremsstrahlung spectra and peak-to-background ratios were studied.

The Monte Carlo electron trajectory calculations were determined with a screened Rutherford cross-section and a plural scattering model. The continuum x-ray depth profile is computed using Kramer's bremmstrahlung cross-section. The cross-section for inner shell ionization proposed by Green and Cosslett were employed for calculating characteristic x-rays. Bethe stopping power was determined by using the Luo-Joy modification at low energies. The mass absorption coefficient was calculated using Heinrich expression. The detector efficiency was determined experimentally.
Angle-energy analyzers of back-scattered electrons for layer-by-layer diagnostics of microelectronics devices in Scanning Electron Microscope
Authors: Likharev S.K.
Published: June 2020

In previous work it was shown that it was possible to visualize depth microstructure of solidstate samples in layer-by-layer form using some modifications of the back-scattered electron (BSE) detector system in the scanning electron microscope. The approach is based on the idea to detect not all of the BSE current, but only the part of it with the directions of velocities close to inverse to the primary beam and energies within a small window in the high-energy part of the whole spectrum. The fact is that when primary electrons scatter in sample, consisting only of light elements, the process of their elastic scattering can be formally divided on two-parts: small-angle scattering and large-angle scattering. In this case the probability of small-angle scattering is approximately five orders higher than large-angle scattering. Taking into account that energy of an electron can be considered as decreasing continuously, if an electron scatters in a sample and comes out with the velocity mentioned above, one can say, that it most probably passed exactly one large-angle scattering in a sample media.
Characterization of cation oxidation states in geologic materials
Authors: McGuire Anne V. , Darby Dyar M.
Published: June 2020

One shortfall of electron microprobe analysis is the inability of x-ray spectroscopic methods to distinguish multiple valence states of atoms. In geologic materials, many elements (eg. Fe, Ti, Cr, Mn, Cu, Eu) may exhibit multiple valence states and their quantitative analysis can be important in solving geologic problems. For instance, Fe2+/Fe3+ ratios in minerals may be useful in determining the oxygen fugacities in which rocks equilibrated. In the past, wet chemical methods were generally used to analyze mineral compositions and Fe2+/Fe3+ ratios were routinely determined. The advent of electron microprobe analysis was accompanied by a decrease in determination of iron oxidation states. The modern microprobe analyst generally deals with the inability to measure Fe2+/Fe3+ ratios by picking one of several assumptions: (a) treat all iron as Fe2+; (b) treat all iron as Fe3+; or (c) calculate an Fe2+/Fe3+ ratio using assumptions of perfect mineral stoichiometry and charge balance. Since almost all iron-bearing minerals contain both Fe2+ and Fe3+, the first two treatments are obviously unsatisfactory.
Electron Stopping Powers and their Experimental Determination
Authors: Joy David C , Luo Suichu , Zhang Xiao
Published: June 2020

Electron stopping power is one of the most important fundamental parameters describing the interaction of an electron with a solid. The magnitude of the stopping power and its variation with energy determines the range of the electron, the rate of production of secondary electron, electron-hole pairs, and the exact form of the ϕ(ρz) curve. In its simplest form the stopping power, i.e the energy dE transferred to the sample of density ρ, atomic number Z and atomic weight A, as the electron of energy E travels a distance ds, is:

(1)

where the mean ionization potential I represents all of the possible inelastic scattering events available to the electron and is, to a zero-order approximation, about 11.6*Z eV. It has been well established that equation (1) is an accurate prediction of the stopping power at energies E of the order of tens of keV, but at the lower energies (i.e <10keV) of most interest for microprobe analysis and scanning microscopy the situation is more complicated.
Experimental Evaluation of Absolute X-RAY Intensities at Low to Moderate Beam Energies
Authors: Armstrong John T. , Carpenter Paul K.
Published: June 2020

Knowledge of the absolute electron-induced production of the characteristic x-rays for different lines and elements is required for proper evaluation of the characteristic fluorescence correction or for development of “standardless” x-ray quantitative analysis correction procedures. Determination of absolute generated x-ray intensities in thick specimens or even relative generated x-ray intensities for lines of different elements in thick specimens is quite difficult as demonstrated by the lack of agreement of the published attempts to determine absolute generated x-ray intensity yields. The amount of absorption of the generated x-ray intensity in the sample and the amount of x-ray production from secondary fluorescence by other characteristic lines or by the continuum must be calculated. Moreover, the detector efficiency for measuring the different lines must be known. Most investigations of absolute generated x-ray intensities suggest that there is a functional relationship between the generated intensity and the overvoltage (U = Eo/Ec) at which the measurement is made.
ϕ(ρz)-Determination for Advanced Applications of Electron Probe Microanalysis
Authors: Karduck Peter , Ammann Norbert
Published: June 2020

In the last 35 years electron probe microanalysis (EPMA) has developed to a versatile technique for the quantitative analysis of materials on a microscopic scale. This development has been initiated by the pioneering work of Castaing in 1951 (1). Already in 1955 Castaing and Descamps have introduced a basic formulation for the absorption correction to quantify characteristic x-ray data (2). This correction already presumed the knowledge of the distribution ϕ(ρz) of the generated x-ray intensity as a function of the depth ρz inside the target. The authors presented the first experimental procedure to determine this distribution for pure elements by the so called sandwich sample technique. The results of this early work, obtained for several pure elements, became a standard in the field and many authors have examined their theoretical approaches or their Monte-Carlo simulations of ϕ(ρz) by means of these ϕ(ρz) data. In the following time further attempts of ϕ(ρz) determinations by experiments or by theoretical approaches, e.g. Philibert (3), became necessary because a general application of a matrix correction to the whole elemental range, detectable by EPMA, required a generalized analytical description of ϕ(ρz).
EELS Study of Phase Separation in Glasses
Authors: Qing Chen Quan , Ming Chu Yi , Feng Duan Xiao
Published: June 2020

The phase separation in glasses plays a great role in the glass science and technology. By controlling the chemical composition and the degree of phase separation, it is possible to produce various kinds of materials of predicted microstructure. To determine the kinds of separated phases, the chemical composition and the fraction or sizes of each separated phase are the main problem in thermodynamics and kinetics study of phase separation in glasses. The sizes of phase separated particles are usually in the range of several nm to several hundred nm, which can be determined by a rather simple method instead of the small angle x-ray scattering with trivial calibration. It has been showed that electron energy loss spectroscopy (EELS) not only can be used to determined the constituents of at. No. 2-92 but also is more sensitive than EDS.

Two phase separated glasses of initial composition 8Na2O27B2O3 65SiO2 and 60ZrF431BaF25LaF34AlF3 were used to prepare specimens by ion bombardment.
An attempt to get an EEL filter image of biological sections using a spectrometer and a scanning device
Authors: Futaesaku Yutaka , Sekiya Kachiko , Ono Michiko , Nakamura Atsushi , Nakamura Yoshiko , Ueno Masaki
Published: June 2020

An amount of light elements contained in biological specimens is barely a few, so that the detection of them in the ultrathin sections is imposible. An analysis of electron energy loss (EEL) filter image is an ideal to detect such as phosphorus including in the sections. CEM-902 is a commercially available electron microscope to use for a such purpose. The authers attempted to get EEL filter images using the combined system of a conventional scanning transmission electron microscope (STEM) with EELS analyzer.

The cultured cells with calcified substances and the liver, kidney, thyroid gland were used for biological specimens. There were fixed with 2.5% glutaraldehyde and with or without 1% osmium tetroxide, and then embedded in epoxy resin. 40 run thick sections were analyzed without any staining and carbon coating using a Carl Zeiss CEM-902 or a JEOL 2000EX with a EELS analyzer and a Tracor-Northern TN-5500, and with a Gatan cryo-transfer holder.
Electronic Structure of Cu-Pd Alloys
Authors: Menon E. S. K. , Krishnan K. M. , Huang P. , Echer C.J. , Singh P. , deFontaine D.
Published: June 2020

Cu-Pd alloys containing 12.6-60.6 at% Pd, when quenched from the fee phase field are known to exhibit diffuse scattering at the 100 and the 110 positions in reciprocal lattice and these diffraction effects are believed to be characteristic of the short range order(SRO) present in these alloys[1]. Moreover, quenched fcc alloys containing more than 13 at% Pd actually exist in a state of modulated SRO, i.e., the diffuse intensity maxima at 100 and 110 reciprocal lattice positions are associated with two-fold and four-fold splitting respectively [1,2]. These effects arise as a result of accidental minima in the ordering potential, V(k) in reciprocal space located away from the special point of the fee structure [2]. Another explanation for the above diffraction effects is from the theory due to Krivoglaz [3] and Moss [4] according to which the long range oscillatory part of V(k) plays a significant role in these alloys and Pd additions increase the flat portions of the Fermi surface of Cu in the <110> directions and this is manifested in the form of strong Kohn like anomaly surfaces in reciprocal space [1,4].
AEM Characterization of Particles in Electrodeposited Chromium Plates
Authors: Chang Li , Tsai Rung-Ywan , Wu Shinn-Tyan
Published: June 2020

Electrodeposited Cr plating has been used for steel surface hardening since 1930. It is well known that there are particles precipitated during annealing the plate. However, no direct evidence has been shown to identify the species of the particles. Despite several microstructural characterizations having been carried out about thirty years ago it is surprised that no research has been done yet for the past decade to take the advantage of the powerful strength of modern electron microscopy. The present work reports the identification of the particles on the basis of AEM study.

Cr plates were deposited on plain carbon steels by conventional method using a standard solution containing CrO3 250 g/l and H2SO4 2.5 g/l at a current density 40 A/dm2 and 45°C. The plates of 0.1mm thickness were then stripped off from steel substrate by dilute HNO3 before annealing was carried out in vacuum at 600,700, and 800°C for 1 to 6 hours.
Defining the Surface-Adsorbed Oxygen Layer with the Channeling Effect in Reflection Electron Energy Loss Spectroscopy
Authors: Wang Z. L. , Bentley J.
Published: June 2020

Channeling conditions or resonance conditions have to be satisfied in order to enhance image contrast in reflection electron microscopy (REM) and the signal to background ratio in reflection electron energy-loss spectroscopy (REELS). The introduction of the channeling effect can complicate surface microanalysis, but could be used to detect surface adsorbed molecules.

An α-A12O3 (01) surface can be terminated with a layer of O−2 or a layer of Al+3. For the surface domain terminated initially with O−2, the oxygen ions will become positively charged after losing three Auger electrons. Then the O+1 ions will be desorbed by the electron beam and the surface 2-D periodic structure becomes disturbed and shows dark rough contrast in the REM image (the dark domain in Fig. 1). Regions of the newly formed surface are terminated with Al+3. For the domain terminated initially with Al+3, the surface is believed to be oxidized quickly in air and is covered by a thin “amorphous” layer, which does not affect the image contrast but protects the surface from being damaged; then the surface shows smooth bright contrast in REM (the bright domain in Fig. 1).
An Aberration-Minimized Imaging Energy Filter of Simple Design
Authors: Krahl Dieter , Pätzold Hans , Swoboda Manfred
Published: June 2020

The installation of an imaging energy filter extends the imaging and analytical capabilities of a conventional transmission electron microscope considerably (contrast and resolution improvement, filtering of diffraction diagrams, EELS and elemental mapping, recording of angle-resolved energy spectra).

Unfortunately, second-order aberrations especially in purely magnetic systems, known up to now, disturb the resolution in off-axis areas of the transferred image. Furthermore, an aperture aberration in the energy-dispersive plane introduces in off-axis areas a shift of the selected energy range. In principle these aberrations can be corrected by inserting sextupole correctors and/or curved edges. But it should be mentioned that the achievable correction of such an improved filter very strongly depends on a proper alignment of the beam.

We describe an aberration-minimized purely magnetic energy filter. The imaging properties of the system were calculated taking into account the exact fringing fields of the reflection magnets. The system was tested on a Zeiss microscope.
The Application of Bio-Standards for Electron Energy-Loss Analysis of Biological Materials
Authors: de Bruijn Wim C. , Sorber Lianne W.J.
Published: June 2020

The application of standards, with a known externally determined element concentration, for the determination of unknown concentrations in cell organelles and tissue is a well known practice in X-ray microanalysis.

The conditions to be met for a good standard have been formulated earlier. Pure element standards and standards made from PVP-films have been proposed for Electron Energy loss analysis. In this presentation we investigate the use for EELS-analysis of the ion-exchange bead Chelex100-type of standards, which can be co-embedded with tissue and have been applied successfully for X-ray microanalysis.

The ion-exchange characteristics, the methods of loading and the matrix composition have been described before. Such bio-standards, which can be loaded with a variety of cations, are stored as a dry powder and can be co-embedded with the tissue to be analyzed. In that way the standard is present in each ultrathin section, at (an assumed) equal thickness as the cells or tissue, containing the unknown concentration of that element.
Development of a Field Emission TEM and Some Applications in Materials Science
Authors: Hashimoto T. , Isakozawa S. , Ichihashi M. , Kamino T.
Published: June 2020

We have completed development of a cold field emission TEM , Model HF - 2000 at Hitachi, Ltd. in Japan. The HF - 2000 has the following unique features.

1)

High sensitivity and precise elemental micro-analysis is possible with a high intensity beam of a cold field emission source.

2)

Crystal structure analysis by electron diff-raction technique with a fine probe of high coherency (small illumination angle).

3)

High resolution imaging beyond the conventional limits of thermionic elecron sources will be made possible by a beam of high coherency and small energy spread.

Condenser lens system of the HF - 2000 has been designed for ease of operation just as the conventional instruments. The beam current density available on the specimenis about 100 times greater than that available with conventioal instruments.

Fig. 1 is a TEM image of Pd/Te particles on carbon with electron diffraction patterns of two partciles A and B. Fig . 2 shows two EDX spectrum of the same two particles.
Spectral Deconvolution of Wavelength Dispersive X-RAY Spectra
Authors: Rémond Guy
Published: June 2020

X-ray peaks frequently exhibit asymmetrical shape which may result either from the mechanisms of generation of X-ray photons or from instrumental spectral distortions. As a result a non-proportionality may occur between the observed and the true intensities of the analyzed emissions. An analytical description of the shape of an X-ray line must be used in a least-squares fitting procedure in order to derive the relative intensities from experimental spectra. The available models will be discussed taking into account the analyzed energy domain and the energy resolution of the spectrometer respectively.

For the case of wavelength dispersive X-ray spectrometry, Remond et al. (1) showed that the shape of an L emission peak P(λ), analyzed by means of a LiF (200) monochromator (≈ 0.1nm < λ < ≈ 0.3nm) was correctly described by the use of equation [1].

[1]

where P1(λ) and P2(λ) are a Gaussian and a Lorentzian distribution respectively, centered at the same wavelength, with the same amplitude and half-width at half-maximum Γ, (HWHM) and in relative proportion k.
Software Tools for Examination of Microanalytical Images
Authors: Bright David S.
Published: June 2020

Image processing for enhancement and interpretation is a powerful tool for microscopy and microanalysis. Digital images are arrays of picture elements or pixels each having a coordinate (location) and a value. Two dimensional arrays with single intensity value (monochrome) or triple intensity values (color) pixels are in common use. Software tools and techniques are now available for desk top computers at reasonable cost that allow visualization of higher dimensional arrays and multivalued pixels. The following examples illustrate the application of these tools to microanalysis.

Short image sequences (movies) are useful for showing dynamic effects such as the drift of an electron microscope stage with time or the interior of a sample eroded by sputtering on an ion microscope.

The values of the pixels of registered images or x-ray maps can be accumulated in a multidimensional histogram (Concentration Histogram Image or CHI). The number of registered maps determines the dimensionality of the histogram.
An SEM Study on Acid Activated Monotmorillonite
Authors: Shu nian Li
Published: June 2020

Under an action of acid the monotmorillonite is changed in the shape, chemical composition, construction and chemical-physical properties. Such changes ralete with concentration and quatity of the acid. The change law has been studied by SEM, EDAX and X-ray diffraction.

All process that the monotmorillonite with shape of cotton and scale is disintegrated gradually is observed by SEM. Begin the monotmorillonite ture into losse and appear holes, increased with concentration of the acid, finally it disntegrate into many of small particles(Figures 1-4).

Changes of chemical composition of the monotmorillonite have been determined by EDAX very conveniently and quickly. The results show that content of SiO2 is increase and Al2O3, Fe2O3,MgO, Na2O, K2O, CaO, TiO2 is dectease.

The results of X-ray diffraction and differential thermo-analysis show the process that crystal construction of the monotmorillonite is destroyed under acidic action, i. e., increased with concentration of the acid, d001 and d060 peakes disappear gradually.
Microanalytical Identification of a New Zr-Nb-Fe Phase
Authors: Woo O.T. , Carpenter G.J.C.
Published: June 2020

To study the influence of trace elements on the corrosion and hydrogen ingress in Zr-2.5 Nb pressure tube material, buttons of this alloy containing up to 0.83 at% Fe were made by arc-melting. The buttons were then annealed at 973 K for three days, furnace cooled, followed by ≈80% cold-rolling. The microstructure of cold-worked Zr-2.5 at% Nb-0.83 at% Fe (Fig. 1) contained both β-Zr and intermetallic precipitates in the α-Zr grains. The particles were 0.1 to 0.7 μm in size, with shapes ranging from spherical to ellipsoidal and often contained faults. β-Zr appeared either roughly spherical or as irregular elongated patches, often extending to several micrometres.

The composition of the intermetallic particles seen in Fig. 1 was determined using Van Cappellen’s extrapolation technique for energy dispersive X-ray analysis of thin metal foils. The method was employed to avoid corrections for absorption and fluorescence via the Cliff-Lorimer equation: CA/CB = kAB · IA/IB, where CA and CB are the concentrations by weight of the elements A and B, and IA and IB are the X-ray intensities; kAB is a proportionality factor.
Changes in corneocyte element concentrations occur in skin inner stratum corneum
Authors: Warner R. R.
Published: June 2020

Keratinocytes undergo maturation during their transit through the viable layers of skin, and then abruptly transform into flattened, anuclear corneocytes that constitute the cellular component of the skin barrier, the stratum corneum (SC). The SC is generally considered to be homogeneous in its structure and barrier properties, and is often shown schematically as a featureless brick wall, the “bricks” being the corneocytes, the “mortar” being intercellular lipid. Previously we showed the outer SC was not homogeneous in its composition, but contained steep gradients of the physiological inorganic elements Na, K and Cl, likely originating from sweat salts. Here we show the innermost corneocytes in human skin are also heterogeneous in composition, undergoing systematic changes in intracellular element concentration during transit into the interior of the SC.

Human skin biopsies were taken from the lower leg of individuals with both “good” and “dry” skin and plunge-frozen in a stirred, cooled isopentane/propane mixture.
Electron probe analysis of calcium and magnesium movements in photoreceptor endoplasmic reticulum
Authors: Baumann Otto , Walz Bernd , Somlyo Andrew P.
Published: June 2020

Various physiological stimuli mobilize Calcium from an intracellular store by a reaction cascade comprising a cell-surface receptor, a coupled G-protein, a phospholipase C and inositol 1,4,5-trisphosphate. Although there is strong evidence that the endoplasmic reticulum (ER) is the target of Ins(l,4,5)P3 and regulates cytoplasmic Ca in non-muscle cells some authors still claim that a specialized, independent cell organelle is the Ins(l,4,5)P3-sensitive Ca-store. The purpose of our study was to determine, with electron probe x-ray microanalysis, the elemental composition of the ER in situ, at rest and during cell stimulation.

We used honey bee photoreceptors because their large ER-cisternae allow direct sampling of the luminal contents without cytoplasmic contamination (Fig. 1). Retinal slices were incubated in a Ringer solution which contained 400 mM sucrose to increase the osmolarity and to serve as cryoprotectant. The slices were frozen with a LifeCell CF 100 slam-freezer either while dark-adapted or after a 3 sec light stimulus.
X-ray microanalysis of calcium content in secretory granules of goblet cell of the rabbit oviduct
Authors: Villalón Manuel , Johnson Dale E. , Verdugo Pedro
Published: June 2020

Secretory granules have two ubiquitous features: they are acidic, and they contain a distinct combination of a two countercharged species: a polyanion, which is usually interconnected forming a polymer network, and a cation or polycation. In most endocrine cells the polyanion belongs to the chromogranin/secretogranin family of acidic proteins, while the polycation is usually the hormonal or transmitter species itself (amines, regulatory peptides, hormones), or else a metallic cation (Ca++, K+, Mg++)(Ann. Rev. Physiol 52:625,1990). In exocrine secretion, like in serous cells, the polyanic polymer network is made of proteoglycans and the shielding cations are a family of polycationic proteins that include lysozyme, lactoferrin, and antileucoprotease (Ann. Rev. Physiol. 52:97,1990). We have proposed that the role of cations or polycations in the granule is to facilitate the condensation of secretory products by screening the polyanionic charges of the secretory networks (Ann. Rev. Physiol. 52:157,1990). In goblet cells of the oviduct, the polyanionic polymers are mucins, while the correponding cationic species has not been identified. In this study x-ray microanalysis was used to determine the presence of a shielding cation(s) in secretory granules of goblet cells of the rabbit oviduct.
Contribution of x-ray total reflection to the background intensity in EPMA
Authors: Rehbach Werner P. , Karduck Peter
Published: June 2020

In the EPMA of soft x rays anomalies in the background are found for several elements. In the literature extremely high backgrounds in the region of the OKα line are reported for C, Al, Si, Mo, and Zr. We found the same effect also for Boron (Fig. 1). For small glancing angles θ, the background measured using a LdSte crystal is significantly higher for B compared with BN and C, although the latter are of higher atomic number. It would be expected, that , characteristic radiation missing, the background IB (bremsstrahlung) is proportional Zn by variation of the atomic number of the target material. According to Kramers n has the value of unity, whereas Rao-Sahib and Wittry proposed values between 1.12 and 1.38 , depending on Z, E and Eo. In all cases IB should increase with increasing atomic number Z. The measured values are in discrepancy with the expected ones.
A further developed Monte Carlo model for the quantitative EPMA of complex samples
Authors: Ammann Norbert , Karduck Peter
Published: June 2020

In its conventional application the electron probe microanalysis (EPMA) is a suitable technique for the quantitative microanalysis of samples, which are homogeneous inside the excited volume. Depending on the beam energy and the target composition the measured x-ray intensities are emerging from depths between about 50 nm and some microns. They contain an integral information about the composition of the excited volume. Nevertheless, the sensitivity of this technique also allows the detection of thin films on substrates with thicknesses even less than one monolayer. For such samples composed inhomogeneously near the surface, e.g. thin layers on substrates or sandwich structures, detailed quantitative informations can only be obtained when the integral information can be deconvoluted properly from the intensities. A necessary prerequisite to solve this problem is the exact knowledge of the depth distribution of the generated x-ray intensities ϕ(ρz) in samples which are inhomogeneous inside the excited volume. Up to now ϕ(ρz) is rather unknown for such samples.