bluuebunny/crossref_metadata_2025 huggingface dataset:
Standardless Quantification of Conductive Oxides In The Sem
Authors: Dijkstra JM , Shen RB
Published: July 2020

In the last 10 years the development of new polymer type detector window materials has dramatically increased the opportunities for light element analysis with Energy Dispersive Spectrometers (EDS). With the introduction of light-element analysis the need also arises to accurately quantify X-ray spectra. Traditional quantification techniques, using a probe current measuring device and pure elemental standards, have been introduced into the field of EDS, but these techniques prevented much of the conveniences of the EDS techniques with respect to speed and ease of use. Many users are therefore willing to sacrifice part of the maximum achievable accuracy in return for a method that is more convenient: standardless analysis.

With EDS analysis the widely published ZAF and φ(ρz) models can be used to convert relative intensities into weight percentages, but for standardless analysis the inaccuracy of the result is mainly caused by the reference intensities.
Trace Element Detection In Particle X-Ray Spectrum
Authors: Small John A
Published: July 2020

One of the main goals of automated scanning electron microscopy analysis (ASEM) of particles is to provide macroscopic phase and compositional information on particle populations based on the energy dispersive x-ray spectrometry, EDS, analysis of several hundred to several thousand individual particles from the sample. The selection and identification of the various elemental groupings is often accomplished by applying techniques for grouping data, such as multivariate or cluster analysis methods, to characteristic x-ray intensities or normalized elemental concentrations. Particle groupings are often based on major and minor elements with concentrations greater than about 1-2 wt. percent. At these concentration levels, the peak-to-background ratios for the characteristic x-ray peaks are sufficiently large that in the absence of severe peak overlaps the elements can be easily identified even in spectra with poor counting statistics. Additional refinement in particle groupings may be possible if reliable information can be obtained on the trace elements present in particles at less than about 1-2 wt.%.
Where Art Thou, Calcium?
Authors: Bailey GW , Dimlich RVW , Alexander KB , McCarthy JJ , Pretlow TP , Somlyo AP
Published: July 2020

Ever since the recognition of calcium as a major intracellular messenger of signal transduction, its subcellular localization and intracellular movements have been intensively sought through electron and light optical methods. Electron probe microanalysis (EPMA), X-ray mapping, electron energy-loss spectroscopy (EELS) and energy-filtered imaging still provide the highest spatial resolution for measuring total calcium, whereas with light optical methods (fluorescent, luminescent and absorbance dyes) free [Ca2+]i can be measured with high sensitivity and time resolution. This presentation will summarize the relationship, whether collision or convergence, between the results of electron and light optical methods, with particular reference to mitochondrial Ca, and consider the potential for further improvements in detection sensitivity and spatial resolution.

Sarcoplasmic and endoplasmic reticulum: Early attempts to quantitate Ca in cellular organelles with EPMA were directed at the sarcoplasmic reticulum (SR) of skeletal muscle, where EPMA could also address questions not amenable to studies of isolated SR.
Esi Analysis Shows Alveolar Epithelial-Like Cells Ingest 50 Nm Titanium Dioxide Particles
Authors: Stearns RC , Godleski JJ
Published: July 2020

Although alveolar macrophages are the primary defensive cells of the lung against invading bacteria and foreign particles, recent studies suggest that particle uptake and translocation is a role common to alveolar epithelium (reviewed by Churg). The purpose of this investigation is to define the phagocytic capabilities of human A549 cell line using 50 nm inert Titanium Dioxide, (TiO2), particles.

A549 cells at 0.5×l06cells/ml, in F12 Kaighn’s modification medium (F12K) with 10% heat-inactivated fetal bovine serum, l00U/ml penicillin and lOOng/ml streptomycin were cultured on alcar discs in 24-well plates, incubated at 37°C, 5% CO2 in a humidified incubator for 4 days. The cells were then exposed to TiO2 particles (final concentration 4Oμg/ml) in serum-free F12K media for 24 h. After 24h, the cells were fixed in 2.5% glutaraldehyde in 0.1 M potassium phosphate buffer overnight. The cells were post-fixed with 1% OSO4, dehydrated in series of ethanol and propylene oxide, infiltrated and embedded with araldite 502.
What Are Present Limits of Quantitative High Resolution Tem?
Authors: Kisielowski Christian
Published: July 2020

In recent years quantitative high resolution electron microscopy (HREM) became a reliable tool to investigate physical processes at an atomic scale. Certainly, there is no unique approach to quantify the information content from lattice images. However, specific methods like Chemical Imaging^ and QUANTITEM were established that allow to investigate the atomic structure of crystalline solids quantitatively and almost routinely.

Nevertheless, there are limits to the application of these methods and they are of principle and of practical nature. Obviously, the resolution of quantitative HRTEM is limited by the point resolution of modern microscopes that has reached 0.1 mn. However, the quantification of the information from lattice images requires two important steps, namely, the application of a pattern recognition procedure and the extraction of changes of the electron scattering potential from the lattice images. The application of the pattern recognition procedure influences the lateral resolution of the method because a lattice image has to be broken up into unit cells of identical size (figure 1).
Extraction of Information From Stem-Edx Segregation Profiles Using Multivariate Statistical Analysis
Authors: Titchmarsh J M
Published: July 2020

Multivariate Statistical Analysis (MSA) has been applied to spectroscopic data acquired by various methods but only recently to EDX spectra acquired in the transmission electron microscope where segregation sensitivity was improved by a factor of x2-3. Equilibrium segregation data were ideally suited for MSA analysis. Each spectrum was composed of a linear sum of contributions from the segregation layer and the two adjacent grains or phases, in proportions determined by the probe current distribution and location. MSA successfully identified an eigenvalue explicitly associated with segregation. Smaller eigenvalues related to self-absorption and coherent bremsstrahlung (CB) were also revealed. The use of an orthogonal MSA constrained the information sources to be independent. This constraint, which was reasonable for equilibrium segregation, has now been examined for a more complicated case: thermally and radiation-induced diffusion near an interface where profiles derived by conventional processing have varying features (Fig.l) from which it is difficult to extract real concentration profiles or even qualitative correlations between elements.
Atomic Resolution Electron Energy Loss Spectroscopy of Interfaces
Authors: Pennycook S J , Dickey E C , Wallis DJ , Browning N D , Nellist P D
Published: July 2020

The ability of high resolution STEM instruments to provide EELS data at the ultimate atomic resolution offers significant new insights into interfacial phenomena. Not only can composition profiles now be collected plane-by-plane across an interface, but in addition, the EELS near edge fine structure can be analysed to determine the valence states of atoms at the interface, and hence the nature of the bonding across the interface plane. by applying the spatial difference technique, these effects can be studied quantitatively with high sensitivity.

Atomic resolution EELS played a critical role in explaining a completely unexpected interfacial structure found recently at CdTe/Si interfaces grown by a particular molecular beam epitaxy growth procedure. The high resolution Z-contrast image in Fig. 1 shows the CdTe film to be terminated by Te, but in addition, for several monolayers into the Si substrate, occasional columns show brighter than the surrounding Si, although remaining in the correct position.
Elfs: Energy Loss Fine Structure Analysis in Materials
Authors: Sarikaya Mehmet , Qian Maoxu , Stern Edward A
Published: July 2020

ELFS (energy loss fine structure), similar to XAFS (x-ray absorption fine structure) provides short-range order atomic structural information of crystalline and amorphous materials. Although known quite sometime, ELFS spectroscopy only until recently has gained importance, mainly due new developments in spectrometer and TEM designs, spectra acquisition and interpretation techniques. This paper focuses on some new developments in the acquisition, interpretation, and the use of the extended regime of the ELFS spectroscopy.

Although fine structure spectroscopy in EELS and its similarity to XAFS were recognized sometime ago, ELFS has only seen limited use mainly because of insufficient spectral statistics, various systematic errors and drifts, and the absence of sophisticated software that faithfully uses the XAFS software and incorporates the latest advances in modeling theory. We have systematically improved the data acquisition technique and developed ELFS data analysis procedure which utilizes the sophisticated UWXAFS data analysis software package8 after correction of the differences between ELFS and XAFS data.
Calculation of Electron Energy Loss Near Edge Structure by the Layered Kkr Method
Authors: Rez P , Maclaren JM
Published: July 2020

The analysis of near edge structure on inner shell ionisation edges in electron energy loss spectroscopy (EELS) can lead to new insights on the nature of bonding on an atomic scale. To fully understand the origins of spectral features it is necessary to calculate the near edge structure from a suitable theoretical model. Many of the previously published theories are based on multiple scattering of the ejected electron in a cluster of atoms surrounding the site of the excitation. The techniques used for the selection of scattering paths account for most of the differences between the various theories. In the XANES method the atoms in the vicinity of the excited atom are assigned to coordination shells and a separation is made between scattering within a given shell (intrashell) and scattering between shells (intershell). The FEFF method selects paths up to a given maximum length according to the number of scatterings and estimated amplitude.
Practical Estimation of Analytical Sensitivity for EDS in an Intermediate Voltage FEG-STEM
Authors: Watanabe M , Ackland D W , Williams D B
Published: July 2020

One of the ultimate objectives for energy-dispersive X-ray spectrometry (EDS) in the analytical electron microscope (AEM) is single-atom detection in thin specimens, as well as quantitative microanalysis with high accuracy approaching ±1% relative. In order to realize the single-atom analysis, the design of the AEM has to be optimized with respect to improvements in spatial resolution and detectability limits. The detectability limit, as defined by the minimum mass fraction (MMF), is given by:

where P is the peak intensity of interest, (P/B) is the peak-to-background ratio for that peak, and r is the acquisition time. To improve the sensitivity for analysis, any or all of the variables P, (P/B), and τ should be increased. Intermediate-voltage analytical electron microscopes combined with high brightness field-emission gun (FEG) are expected to improve the MMF, while maintaining high spatial resolution. Additionally, the MMF should also be improved by maximizing the solid angle of X-ray collection.
Energy Filtered Imaging and Convergent Beam Electron Diffraction (CBED) in the Transmission Electron Microscope (TEM)
Authors: Fox AG , Menon ESK , Saunders M
Published: July 2020

Over the last ten years TEMs have been developed that are capable of HREM, EDX, PEELS and diffraction using a single objective pole piece. More recently these TEMs have been equipped with the capability of energy filtering the electron beam after it has passed through the sample so that energy filtered images and electron diffraction patterns can be obtained. In this work the use of a Topcon 002B TEM equipped with a GATAN PEELS imaging filter (GIF) to generate zero-loss energy filtered zone axis CBED patterns and elemental images from inelastically scattered electrons will be described. An analysis of this energy filtered data indicates that elemental imaging using the GIF is an informative, but semiquantitative technique, whereas zero-loss energy filtered zone axis CBED patterns can be accurately quantified so that the two lowest-angle x-ray form factors of cubic elements can be measured with errors of the order of 0.1% or less.
Analysis of Nanometer-Scale Precipitation in a Rapidly Solidified Stainless Steel
Authors: Wisutmethangoon S , Kelly TF , Camus PP , Flinn JE , Larson DJ , Miller MK
Published: July 2020

Though stainless steels are important technologically for a wide range of applications, they are not generally known for their very high strength. We have rapid-solidification-processed many stainless steels by gas atomization and achieved strength improvements of over 50% relative to conventionally-processed stainless steels with concomitant improvement in corrosion and oxidation behavior. These strength improvements are most pronounced after aging treatments when elevated concentrations of oxygen and vanadium are present in the stainless steel. An austenitic (FCC) stainless steel (Fe-16%Ni-9%Cr-0.5%Mn-0.2%V-0.0137%N-0.008%O by weight) was prepared by gas atomization and consolidated by hot extrusion at 900°C. These specimens were heat treated for 1 hour at 1000°C and aged at 600°C for 500 hours.

The microstructure of each alloy composition was observed in TEM with bright field imaging. After aging, most alloys showed the same precipitate morphology as before aging. An obvious change, however, was found only in the alloy with highest oxygen content.
Reactive Gas Plasma Specimen Processing for Use in Microanalysis and Imaging in Analytical Electron Microscopy
Authors: Zaluzec Nestor J , Kestel Bernard J , Henriks David
Published: July 2020

It has long been the bane of analytical electron microscopy (AEM) that the use of focused probes during microanalysis of specimens increases the local rate of hydrocarbon contamination. This is most succinctly observed by the formation of contamination deposits (fig.l) during focused probe work typical of AEM studies. While serving to indicate the location of the electron probe, the contamination obliterates the area of the specimen being analyzed and adversely affects all quantitative microanalysis methodologies. A variety of methods including: UV, electron beam flooding, heating and/or cooling can decrease the rate of contamination, however, none of these methods directly attack the source of specimen borne contamination. Research has shown that reactive gas plasmas may be used to clean both the specimen and stage for AEM, in this study we report on quantitative measurements of the reduction in contamination rates in an AEM as a function of operating conditions and plasma gases.
The Use of a Cold Gas Plasma for the Final Processing of Contamination-Free TEM Specimens
Authors: Fischione PE , Ringnalda J , Feng Y , Krekels T , Colijn HO , Mills MJ , Wiezorek JM
Published: July 2020

The issue of specimen contamination becomes more important at a rate proportional to the use of high-brightness electron source Transmission Electron Microscopes (TEM). These TEMs combine smaller electron probes with increased current, allowing high resolution specimen imaging and enhanced analytical data collection. Small, high current electron probes tend to increase the detrimental effect of hydrocarbon presence on the specimen's surface. The subsequent formation of carbon deposits caused by the focused probe often times obstructs imaging and precludes acceptable analytical results. by plasma cleaning the specimen, contamination is removed and the results obtained by high resolution electron microscopy (HREM), scanning transmission electron microscopy (STEM) and analytical electron microscopy (AEM) using EDS or electron energy loss spectroscopy (EELS) are greatly enhanced. Recent instrumentation developments have resulted in the application of a high frequency, low energy, reactive gas plasma generated in an oil-free vacuum that chemically removes hydrocarbon contamination from both the TEM specimen holder and the specimen without altering its properties.
Determining the 3-Dimensional Structure of Defects in Oxide Materials Using Eels
Authors: Moltaji H , Buban J P , Browning N D
Published: July 2020

Electron energy loss spectroscopy (EELS) is ideally suited for the study of oxide materials. The large cross section for the oxygen K-absorption edge generates enough signal for fine-structure analysis even when the probe is small enough for atomic resolution imaging (∼2Å). Therefore, by using the Z-contrast imaging technique in the STEM to locate defects and position the probe with atomic resolution, detailed spectroscopic information can be obtained from a known atomic location. by selecting the appropriate acquisition conditions, these spectra can have the same atomic resolution and incoherent features as the Z-contrast image. The primary benefit of this methodology is that the image provides a structural model for interpretation of the spectrum through theoretical modeling.

One means of interpreting this spectral fine-structure is through multiple scattering analysis. In the multiple scattering formulation, the fine-structure of the absorption edge is considered to arise from interference effects resulting from the scattering of an excited photoelectron from neighboring atoms.
Martensitic Transformation in a Ti50ni48fe2 Alloy Studied by Eels
Authors: Murakami Y , Shindo D , Oikawa T , Kersker M
Published: July 2020

Martensitic transformation is the first-order diffusionless phase transformation in solids, and is responsible for unique phenomena such as shape memory effect and superelasticity. Recently, many researchers tried to explain the origin of martensitic transformations from a viewpoint of electronic structure. It is strongly required to investigate electronic state changes associated with a martensitic transformation by an accurate experiment. EELS (Electron Energy-Loss Spectroscopy) was successfully applied to study electronic state in several alloys and oxides, e.g. a composition dependence of density-of-state (DOS) in Cu-3d band was clearly observed for Cu1-xAlx alloys by a core-loss measurement. However, this method has been less applied to studies of phase transformations to date. The purpose of the present work is to investigate electronic state changes associated with a martensitic transformation in a Ti50Ni48Fe2 alloy by EELS.

A Ti50Ni48Fe2 alloy was prepared by induction-melting method. Thin-foiled specimens were solution-treated in Ar atmosphere at 1173K for 1hr.,
In-Column Energy Filtering Transmission Electron Microscope (EFTEM) - Integrated Analysis of Energy Loss Signals
Authors: Bauer R , Benner G , Büscher P , Probst W , Seybold V , Zellmann E
Published: July 2020

In an EFTEM the full range of signals generated by interaction of the primary electron beam with the specimen can be detected. Thus operating such a system and generating combined digital information usually is a rather complex issue. The demands of the users on the other hand are to achieve results fast, easily and reproducibly. Moreover it should be possible to tailor the integral system according to dedicated needs. In general it should be no problem to use modern digital equipment and just let an integral computer control everything. However, in order to make such digital settings really useful, there should be no D/A conversion in between the data paths of the microscope because any analogue system tends to drift and the changes of lens parameters between different modes of operation should be minimised to overcome hysteresis. Fully digitised in-column EFTEMs like the LEO EFTEMs with OMEGA filter and Koehler illumination including also multiple parallel and serial remote capabilities provide optimum preconditions to fulfil the demands.
MicroAnalysis of Soot Participates Using STEM
Authors: Bell David C , Rainey Lenore C , Vander-Sande John
Published: July 2020

Overview Scanning transmission electron microscopy (STEM) coupled with energy dispersive x-ray analysis (EDX) and electron energy-loss spectroscopy (EELS) has been used to characterize the elemental composition and oxidation conditions of various soot samples. The STEM employed in this investigation was the Vacuum Generators HB603-MIT, with a microanalyical resolution approaching 1 nm, that allowed the analysis of individual soot particles and aggregates.

The aim of this research is quantification of the EDX spectra which is possible after background and absorption corrections. This information can then be used for comparative studies of different fuels and combustion processes.

EELS has been employed to determine the amount of graphitic carbon in a soot particulate, and the detection of trace elements of low atomic number. It has been shown in soot that for Carbon the energy-loss of the p shell electrons increases with the amount of oxidation at high temperatures.

Analysis and characterization of gas turbine soot, collected from an engine exhaust duct of a 737-300 aircraft showed an abundance of different elements.
Debye-Waller Factor Measurements by Quantitative Convergent Beam Electron Diffraction (CBED)
Authors: Saunders M , Fox A G , Midgley P A
Published: July 2020

Quantitative CBED techniques are now capable of making low-order structure factor measure-ments with sufficient accuracy to study bonding effects in crystalline materials. The main limitation of these techniques has been identified as the accuracy with which one knows the Debye-Waller factor(s) (DWF(s)). Even where X-ray measurements exist, values have usually been determined at room temperature whereas we often want to perform our electron diffraction experiments at liquid nitrogen temperatures to reduce the effects of thermal diffuse scattering (TDS). Attempts to calculate theoretical DWF values have been shown to have limited accuracy when compared to experimental measurements.

This has led to a search for new electron diffraction methods for DWF determination such as the use of HOLZ line segments, high-index systematic rows and electron precession patterns. The aim should be to measure the DWF(s) under identical conditions to those used for the charge density studies, e.g. the same sample thickness, temperature and microscope settings.
Maximum Entropy and Bayesian Methods of Solving the Phase Problem in Electron Diffraction
Authors: Gilmore CJ
Published: July 2020

The phasing of electron diffraction data poses considerable problems for traditional direct or heavy atom crystallographic methods since the data are incomplete or at less than atomic resolution (i.e. 1.1Å), and subject to errors arising from dynamical scattering effects. The Bricogne formalism for phasing diffraction data using maximum entropy (ME) and Bayesian methods has proved especially useful in these situations1 since this formalism is stable irrespective of data resolution and completeness, and is robust with respect to errors on the measured diffraction intensities.

Successes with this formalism this include a wide range of structures: (1)The ab initio phasing of diketopiperazine C4H6N2O2 (Fig 1).(2)The structure solution of CuCl2.3Cu(OH)2 (Fig 2).(3)The ab initio phasing of two 2-D membrane data sets at ca. 6Å resolution without the use of image phases (Halorhodopsin and Omp F Porin4 - Figs 3 and 4). In addition, we have had some success in phasing the 3-D data of bacteriorhodopsin at 6Å.
The Use of Phase and Amplitude Information of Reconstructed Exit Waves
Authors: Zandbergen HW
Published: July 2020

Exit waves can be reconstructed from through focus series of HREM images or by off-axis holography [1]. We have applied the through focus method to reconstruct exit waves, using algorithms developed by Van Dyck and Coene [2]. Electron microscopy was performed with a Philips CM30ST electron microscope with a field emission gun operated at 300 kV. The high resolution images were recorded using a Tietz software package and a 1024x1024 pixel Photometrix CCD camera having a dynamic range of 12 bits. The reconstructions were done using 15-20 images with focus increments of 5.2 nm. The resulting exit waves were corrected posteriorly for the three fold astigmatism.

The exit wave is complex; consequently it contains phase and amplitude. Since in the very thin regions the specimen acts as a thin phase object, such a thin area will show little contrast, an example of which is shown in Figure 1.
3-D Structure of a Water Channel At ˜6Å Resolution as Determined by Electron Crystallography
Authors: Jap BK , Li H-L , Lee S
Published: July 2020

Aquaporin-1 (AQP1) is a class of water channels within the aquaporin superfamily. These channel proteins have been found in a wide variety of tissues such as kidney, lung, eye secretory gland and intestinal epithelium as well as in vacuolar membranes of plants. The major function of these channel proteins is to transport water exclusively into and out of cells. Based on amino acid sequence, it has been predicted that aquaporins contain six lipid bilayer-spanning a-helices. Models for the molecular folding of AQP1 containing six and four transmembrane a-helices have been proposed previously. Our earlier projection map at 3.5Å resolution revealed eight high density peaks which we interpreted as the projections of seven transmembrane α-helices and an eighth possibly transmembrane segment. The juxtaposition of structures seen in the projection map prevented us from unambiguously determining the exact number of transmembrane helices based on the projection map alone. We report here the three-dimensional (3-D) map at ˜6 Å resolution as determined by electron crystallography.
Inelastic Scattering and Interference
Authors: Van Dyck D
Published: July 2020

Recently it has been a matter of controversy whether inelastically scattered electrons can yield interference fringes so as to obtain holograms, and in particular whether compensation of energy loss in the object by energy gain in the source will maintain coherence [1]. In discussions about coherence (and wave mechanisms in general) it is always dangerous to rely on intuitive arguments (exchange of energy, time of interaction, etc.). In this work we will start from the most general approach, which is inspired by the treatment of inelastic electron diffraction crystals by Yoshioka in 1957 [2]. Energy exchanges are always described quantummechanically by an Hamiltonian. Therefore we can only investigate the balance between energy exchange properly if electron, object, and source are described by one global Hamiltonian. With source we mean the whole electron generating system (emitter, accelerator, condensor).

Consider a global system consisting of an electron, with position vector r, an object with particle vectors ri, and a source with particles at rα.
Models of Magnesium Oxide (111) Surface Reconstructions Obtained from Direct Phasing of Transmission Electron Diffraction Data
Authors: Plass R , Egan K , Collazo-Davila C , Grozea D , Landree E , Marks L D , Gajdardziska-Josifovska M
Published: July 2020

It has long been thought that (111) surfaces of rock salt oxides microfacet to neutral surfaces upon annealing because of the very large energies involved in bulk terminating a layer of like ions. However in a recent reflection electron microscopy (REM) study Gajdardziska-Josifovska et al. found that MgO(lll) surfaces annealed in flowing oxygen furnaces at 1500°C not only did not microfacet, but displayed a √3×√3R30° surface periodicity that was stable in air. To determine the structure of this unusually stable surface MgO (111) transmission electron microscopy (TEM) samples were annealed in a vacuum furnace in the present study and their transmission electron diffraction (TED) patterns were analyzed with direct phasing methods.

The TEM samples were prepared by orienting a MgO single crystal and sawing lmm wafers along a (111) plane. Disk samples were then ultrasonically drilled, dimpled, mechanically polished and/or hot nitric acid etched, and milled with 5 KeV Ar+ ions.
Structure of the in on SI(111)4X1 Surface Determined by Applying Direct Phasing Methods to Transmission Electron Diffraction Data
Authors: Bailey GW , Dimlich RVW , Alexander KB , McCarthy JJ , Pretlow TP , Collazo-Davila C , Marks L D , Nishii K , Tanishiro Y
Published: July 2020

Direct methods were applied to transmission electron diffraction data to solve the previously unknown In on Si(111)4x1 surface structure. The structure consists of zig-zag chains of In atoms separated by regions of silicon including dimer chains (Fig 1.). The 4x1 structure is one of several stable surface structures formed with increasing In coverages on the Si(111) surface. The √3x√3 structure consists of 1/3 of a monolayer of In, the √31x√31 occurs at a slightly higher coverage and the 4x1 structure appears before the formation of In islands on the surface. While the √3x√3 surface has been extensively studied, relatively little is known about the √31x√31 and 4x1 structures. Knowledge of the atomic positions in the 4x1 structure is an important step in understanding metal/semiconductor epitaxy and interface formation.

Two data sets were used in this study -- the first recorded on film and reduced in Tokyo, the second recorded on Imaging Plate in Tokyo and reduced at Northwestern. Twenty-seven independent intensities were measured.
Electron Holography of Electromagnetic Fields
Authors: Bonevich JE
Published: July 2020

Electron holography can lend crucial insights to understanding the subtle manifestations of electro-magnetism in a wide range of materials. Whereas conventional microscopy is sensitive only to the intensity, holography reveals the phase changes in coherent electron wavefronts making it a unique tool to probe electric and magnetic fields on the nanometer scale. We have employed electron holography to characterize materials for mean inner potential measurements and also their electric and magnetic properties.

Electron holograms were acquired in a 300 kV FE-TEM under two optical conditions: the standard high resolution mode was employed for mean inner potential measurements; to examine the intrinsic electromagnetic states, a lower resolution mode was used whereby the objective lens is turned off and the diffraction lens images the specimen. Digitally acquired holograms were reconstructed with the HolograFREE software package.

Nanophase TiO2 particles generated in a flame burner system were found to have unusual central features. The rutile particles appear to contain faceted voids, raising the question whether the feature is truly a void or a secondary amorphous phase.
Reference Electron Energy Spectra for Quantitative Auger Electron Spectroscopy (AES) : Cu(100), (110), and (111)
Authors: Goto Keisuke
Published: July 2020

We have developed a novel cylindrical mirror analyzer (CMA) for the quantitative Auger electron spectroscopy (AES) to obtain reference electron spectra. This CMA was defined in all respects, thus it yields an absolute electron energy distribution ; the energy resolution of 0.25% for 42.3° ± 6° of incidence angles (theoretically obtainable resolution), the estimated transmission of 6.2% (assuming cosine law), and the signal detection by the combination of Faraday cup and electrometer (SI traceable). The acceleration voltages for the primary electron beam were ranging 1 through 5000 volts and the energy range of the sweep was 0 through 5000 eV in 0.1 eV(min)/step for the whole range and 10 meV or even 0.1 meV/step for the limited narrow range. The energy calibration by using the primary acceleration voltage (SI traceable) and the spectral intensity correction for the relativity have been performed.

The spectra for typical samples have already been published, i.e., C's(soot and graphite), Al(poly), Si(100and 111), Cr(poly), Fe(poly), Ni(poly), Cu(poly), Ga(liquid), Ag(poly), and Au(poly). Among the samples C's and Ga(liquid) seem to be convincing materials.
Design, Construction and Applications of a Low Temperature (5 K) Combined Scanning Cathodoluminescence and WDS X-ray Spectroscopy and Imaging System
Authors: Phillips MR , Moon A R , Stevens Kalceff M A , Remond G
Published: July 2020

Recently there has been a renaissance in scanning cathodoluminescence (CL) microscopy and microanalysis primarily brought about by the analytical demands of the semiconductor industry in addition to significant advances in photonics technology (high efficiency PMTs, CCDs and CL collectors). The strength of the CL analysis technique lies in its ability to provide high spatial (lateral and depth) resolution concentration and distribution information about: (i) the chemical state (identity, oxidation state and co-ordination) of trace level impurities and (ii) point / extended structural defects (vacancies and dislocations) in both semiconductors and insulators.

For many materials, interpretation of CL spectra and images measured at low temperature (5 K) is quite straightforward. However CL generation via recombination of electron / hole pairs is a competitive process. Consequently in some specimens the measured CL intensity is not directly proportional to the concentration of the particular luminescent center but relates to the concentration of other radiative or non-radiative centers. In these cases it is difficult to decide whether contrast in the CL image is due to variation in the concentration of the radiative center or the competitive center.
Use of Polycapillary Optics to Increase the Effective Area of Microcalorimeter Spectrometers
Authors: Wollman D A , Jezewski Christopher , Hilton G C , Xiao Qi-Fan , Irwin K D , Dulcie L L , Martinis John M
Published: July 2020

Although the performance of high-energy-resolution microcalorimeter spectrometers for x-ray microanalysis is encouraging, the future widespread acceptance of these spectrometers as valuable microanalysis instruments depends on improvements in both achievable count rate and geometrical x-ray collection efficiency. While the maximum output count rate of our microcalorimeter (∼160 s−1) is much less than that of conventional EDS detectors operating at their highest energy resolution (∼3000 s−1), we are confident that we can significantly improve the count rate without loss of energy resolution (∼10 eV FWHM over a broad energy range). Increasing the area (and thus solid angle) of the microcalorimeter is a more difficult problem, however, as the best microcalorimeter performance is achieved using small-area (typically 250 μm by 250 μm) absorbers with low heat capacity.

This problem can be solved by using an x-ray lens to increase the collection efficiency of the microcalorimeter spectrometer. A polycapillary optic consisting of tens of thousands of fused capillaries can collect x-rays from a point x-ray source over a large solid angle and focus the x-rays onto the small-area absorber of the microcalorimeter.
In-column energy filtering transmission electron microscope (EFTEM) optimum contrast without disadvantages for all modes of imaging and all kinds of detectors
Authors: Bailey GW , Dimlich RVW , Alexander KB , McCarthy JJ , Pretlow TP , Bauer R , Benner G , Seybold V , Zellmann E , Probst W
Published: July 2020

The major demand for imaging light element specimens in the TEM is to achieve the appropriate contrast. This is particularly true in biomedical and also in polymer fields of application. The main reason for contrast being challenging is the correlation between the atomic number of the constituting elements and the scattering angle and thus the very low scattering absorption contrast achievable.

Different conventional methods or combinations of them can be used to overcome the problem. 1) Contrast is created chemically by staining with heavy elements. Disadvantages besides the high level of preparational efforts are the artificial unnatural view in general and the high potential of artifacts in particular. 2) Contrast is created physically using small objective apertures and/or long focal length objective lenses. Disadvantages are clearly increased alignment and cleaning efforts for small apertures and the complete loss of high frequency/high resolution information. Moreover, some elastic scattering is still required. 3) Contrast is created physically converting phase contrast into absorption contrast using the phase contrast transfer function of the microscope and high defocus values.
Design of an Objective Lens with Minimum Chromatic Aberration Coefficient
Authors: Tsuno K , Jefferson D A
Published: July 2020

The Schelzer resolution is defined as the highest spatial frequency which is transferred into the image with the same phase as all lower frequencies. The resolution of the information limit is, however, determined by the information from the specimen which is equal to the degree of noise. The Schelzer resolution is determined by the wave length and the spherical aberration coefficient Cs of the objective lens. It reached 0.1 nm at 1250 kV. The limit of the resolution has been calculated numerically and it is written as d = 4.65(BsVr)−1/4 (nm), where Bs (in T) is the saturation magnetic flux density of the pole-piece material and Vr the relativistically corrected accelerating voltage. The resolution of the information limit is determined by the axial chromatic aberration coefficient Cc and incoherent effects such as the finite size of the source, beam divergence, energy spread, instabilities of the high voltage and lens current. The limit of the resolution is not clear. Most of the objective lenses of commercial microscopes are designed to optimize Cs rather than Cc. In this investigation, however, we describe the limit of Cc for 200 kV microscopes.
Development of a Double Tilt Specimen Heating Holder and its Application for the Study of Phase Transformation of Si3N4 During Sintering
Authors: Kamino T , Yaguchi T , Tomita M , Yasutomi Y , Hidaka K
Published: July 2020

The results of our previous studies revealed that the specimen heating holder with the heating elements of spiral shaped fine metal wires of high melting point enable us to observe high resolution transmission electron microscopy(TEM) images at elevated temperatures.

In fact, the holder was applied for high resolution TEM study of a formation of SiC crystal at 1500°C and a surface reconstruction of Au deposited Si particle at 1000°C successfully. However, because the heating holder was single tilt type, there was a certain limitation in its application.

In this paper, development of a double tilt specimen heating holder with a heating element of spiral shaped fine metal wire and its application for the study of microstructural changes of Si3N4 during sintering at very high temperature.

Photograph of the newly developed double tilt specimen heating holder is shown in Fig. 1. The heating element is mounted on the electrically isolated tilting frame of the holder and the heating current is supplied via tilting rod which is also electrically isolated from other parts of the holder.
Event-Driven 2D Detector for Digital Electron Imaging
Authors: Fan G Y , Beuville E , Datte P , Beche J-F , Millaud J , Ellisman M H , Xuong N-H
Published: July 2020

An event-driven 2D pixel array detector designed for protein crystallography is being tested to determine its suitability as a direct electron detector for digital imaging in electron microscopy. The detector prototype consists of an 8×8 pixel array with an 150 μm pitch. The device configuration is illustrated in Fig. 1. The detector module consists of a reverse-biased 300 μm thick monolithic silicon diode array which is bump-bonded to an Application Specific Integrated Circuit (ASIC) which instruments each diode in the array. Each pixel cell of the ASIC forms a pixel processor which consists of an amplifier, discriminator, prescalar and readout circuit.

When an incident electron enters the detector, a group of electron-hole pairs is created in the silicon. The detector bias of the diode array is such that holes are collected at the input to the amplifier where the signal is then amplified and shaped. When the output signal pulse height is greater than the discriminator threshold, the event is then registered in the prescalar, causing one count to be accumulated.
Current Trends in Digital Imaging for Optical Microscopy
Authors: Cheng Ping-chin
Published: July 2020

Digital imaging has provided a number of possibilities in optical microscopy which can not be achieved easily by traditional methods. These include the possibility of low-light imaging, ease of image manipulation (processing and analysis) and transmission via electronic communication channels. Recently, digital imaging has become the buzz-word in photography. Therefore, it is the intent of this article to evaluate the current state of digital imaging technologies for optical microscopy, both pro and con.

There are certain applications where digital imaging is the only feasible way to gather image data, examples include laser scanning confocal microscopy and low-light CCD microscopy. Based on the nature of image acquisition methods, one can classify digital imaging into two major domains: (1) sequential and (2) parallel data acquisition. The sequential data acquisition method is generally used in scanning devices such as the confocal laser scanning microscopes (CLSM). Photomultipliers and solid state devices are generally used as the photon detector(s) and the analog signals are subsequently digitized. On the other hand, the use of 2D array detectors such as CCDs falls into the parallel acquisition category. Although, the data from a CCD is read-out sequentially, all the pixels on a CCD chip acquire the image simultaneously. Depending on the dynamic range of the photon detector and needs of the application, the digitized image generally has a dynamic range of 8, 12 or 16 bits.
Integration of a Spatial Map with the Images of Polytene Chromosomes
Authors: Heckman C A , Olesen J B
Published: July 2020

The principle of spatial mapping is familar to microscopists. It is, for example, employed in conjunction with x-ray fluorescence spectrometry to draw up maps showing the distribution of elements in a materials surface. Although widely exploited in scanning electron microscopy, the technique of spatial mapping is rarely applied to other types of images. With the recent development of automated methods for recognizing and extracting details from digital images, however, it has become feasible to extract patterns from the transmission electron microscope image and overlay the original image with representations from the data. Pattern extraction, executed in a data mining scheme, is an area of common interest to researchers in machine discovery, data visualization, and high performance computing. Since the resolution of an electron microscopic image, if completely conserved in the conversion into digital format, can range into many millions of pixels, microscopy is one of the most promising areas for data mining applications.

This capability is particularly well-suited to investigating the problem of chromatin higher order structure. The highest order of packing that is readily seen in transmission electron micrographs of chromatin is the 30 nm fiber, the approximate size of which has been confirmed by x-ray diffraction studies.
Automatic Hough Transform-Based 3D Segmentation of Cell Nuclei in Thick Tissue Sections
Authors: Lockett SJ , Rodriguez EG , Ortiz de Solorzano C , Sudar D , Pinkel D , Gray JW
Published: July 2020

Combining pathology, which reports the structural features of individual cells and their spatial organi-zation in a tissue specimen, with molecular biology techniques (immunocytochemistry and fluores-cence in situ hybridization, FISH) for detecting the distribution of specific molecular species in individual cells is a powerful approach for gaining insight into the underlying disease mechanisms of carcinogenesis. This approach requires analysis of thick (>20 ¼m) tissue sections in which cells are preserved intact within the context of their environment. 3D (confocal) microscope image acquisition followed by 3D image analysis (IA) for extracting quantitative information are then used for quantita-tive analysis of tissue features such as nuclear and/or cell volume, shape, total fluorescence or FISH signal number. An essential component of the IA is detection of the individual cells, or their nuclei since many molecular species of interest are localized within the nucleus (e.g. genetic aberrations). We present here a completely automatic, 3D algorithm for this task, which based on the Hough transform (HT).
Use of High-Performance Computing Algorithms in Combination With Parallel Computing for Tomography
Authors: Perkins GA , Renken CW , Young SJ , Lindsey S , Ellisman MH , Frey TG
Published: July 2020

The electron microscope is essential for resolving complex biological structures, such as mitochondria, which are too small to be viewed in detail with the light microscope. In contrast to a conventional instrument, the High-Voltage Electron Microscope (HVEM) located at the National Center for Microscopy and Imaging Research (NCMIR) can obtain images from relatively thick specimens that contain substantial three-dimensional structure. Though a single image acquired with the HVEM represents a projection through the specimen, tomographic methods can be applied to a set of images acquired from different orientations to derive a three-dimensional representation of its biological structure. Tomography requires extensive computation and considerable processing time on conventional workstations in order to reconstruct the typically large HVEM volumes from the tilt series.

In order to expedite tomographic processing, we have implemented both the commonly used singleaxis tilt, R-weighted backprojection algorithm and two iterative reconstruction methods, algebraic reconstruction (ART) and simultaneous iterative reconstruction (SIRT) on the massively parallel Intel Paragon at the San Diego Supercompter Center.
Recent Development of Cone-Beam X-Ray Microtomography at Sunyab
Authors: Pan SJ , Shih A , Liou WS , Park MS , Wang G , Bohne BA , Newberry SP , Kim H , Cheng PC
Published: July 2020

An experimental X-ray cone-beam microtomographic imaging system utilizing a generalized Feldkamp reconstruction algorithm has been developed in our laboratory. This microtomographic imaging system consists of a conventional dental X-ray source (Aztech 65, Boulder, CO), a sample position and rotation stage, an X-ray scintillation phosphor screen, and a high resolution slow scan cooled CCD camera (Kodak KAF 1400). A generalized Feldkamp cone-beam algorithm was used to perform tomographic reconstruction from cone-beam projection data. This algorithm was developed for various hardware configuration to perform reconstruction of spherical, rod-shaped and plate-like specimen.

A test sample consists of 8 glass beads (approx. 800μm in diameter) dispersed in an epoxy-filled #0 gelatin capsule. One hundred X-ray projection images were captured equal angularly (at 3.6 degree spacing) by the cooled CCD camera at a of 1317×967 (17×17mm2) pixels with 12-bit dynamic range. Figure 1 shows a 3D isosurface rendering of the test sample. The eight glass beads and trapped air bubbles (arrows) in the epoxy resin (e) are clearly visible.