Electron microprobe analysis of Apollo 11 lunar samples
Electron microprobe and petrographic analyses of crystalline rock and separates from apollo 11 lunar soil samples
Adler, I.↗
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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Combined electron microscope, electron diffraction, and electron microprobe analysis of identical microstructures in the debond area of a dissimilar metal joint
Electron microscope, electron diffraction, and electron microprobe analysis of defective solid state weldment on liquid hydrogen tank from Apollo 12 fuel cell system
Bostwick, L. G.↗
Silicate spherules from Tunguska impact area - Electron microprobe analysis.
Oxide composition of silicate spherules from forest area devastated by Tunguska meteorite explosion using electron microprobe analysis
Glass, B. P.↗
Study of microstructure and silicon segregation in cast iron using color etching and electron microprobe analysis
An investigation on silicon segregation of lamellar, compacted and nodular graphite iron was carried out by applying a selective, immersion color etching and a modified electron microprobe to study the microstructure. The color etched micrographs of the investigated cast irons by revealing the austenite phase have provided data about the chronology and mechanism of microstructure formation. Moreover, electron microprobe has provided two dimensional segregation maps of silicon. A good agreement was found between the segregation profile of silicon in the color etched microstructure and the silicon maps achieved by electron microprobe analysis. However, quantitative silicon investigation was found to be more accurate than color etching results to study the size of the eutectic colonies. - Highlights: • Sensitivity of a color etchant to silicon segregation is quantitatively demonstrated. • Si segregation measurement by EMPA approved the results achieved by color etching. • Color etched micrographs provided data about solidification mechanism in cast irons. • Austenite grain boundaries were identified by measuring the local Si concentration.
36 MATERIALS SCIENCE↗
ESR lineshape and {sup 1}H spin-lattice relaxation dispersion in propylene glycol solutions of nitroxide radicals – Joint analysis
Electron Spin Resonance (ESR) spectroscopy and Nuclear Magnetic Relaxation Dispersion (NMRD) experiments are reported for propylene glycol solutions of the nitroxide radical: 4-oxo-TEMPO-d{sub 16} containing {sup 15}N and {sup 14}N isotopes. The NMRD experiments refer to {sup 1}H spin-lattice relaxation measurements in a broad frequency range (10 kHz–20 MHz). A joint analysis of the ESR and NMRD data is performed. The ESR lineshapes give access to the nitrogen hyperfine tensor components and the rotational correlation time of the paramagnetic molecule. The NMRD data are interpreted in terms of the theory of paramagnetic relaxation enhancement in solutions of nitroxide radicals, recently presented by Kruk et al. [J. Chem. Phys. 138, 124506 (2013)]. The theory includes the effect of the electron spin relaxation on the {sup 1}H relaxation of the solvent. The {sup 1}H relaxation is caused by dipole-dipole interactions between the electron spin of the radical and the proton spins of the solvent molecules. These interactions are modulated by three dynamic processes: relative translational dynamics of the involved molecules, molecular rotation, and electron spin relaxation. The sensitivity to rotation originates from the non-central positions of the interacting spin in the molecules. The electronic relaxation is assumed to stem from the electron spin–nitrogen spin hyperfine coupling, modulated by rotation of the radical molecule. For the interpretation of the NMRD data, we use the nitrogen hyperfine coupling tensor obtained from ESR and fit the other relevant parameters. The consistency of the unified analysis of ESR and NMRD, evaluated by the agreement between the rotational correlation times obtained from ESR and NMRD, respectively, and the agreement of the translation diffusion coefficients with literature values obtained for pure propylene glycol, is demonstrated to be satisfactory.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Networks of silicon nanowires: A large-scale atomistic electronic structure analysis
Networks of silicon nanowires possess intriguing electronic properties surpassing the predictions based on quantum confinement of individual nanowires. Employing large-scale atomistic pseudopotential computations, as yet unexplored branched nanostructures are investigated in the subsystem level as well as in full assembly. The end product is a simple but versatile expression for the bandgap and band edge alignments of multiply-crossing Si nanowires for various diameters, number of crossings, and wire orientations. Further progress along this line can potentially topple the bottom-up approach for Si nanowire networks to a top-down design by starting with functionality and leading to an enabling structure.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Extended-chain crystals. V - Thermal analysis and electron microscopy of the melting process in polyethylene
Polyethylene extended chain crystals melting process via electron microscopy and differential thermal analysis
Melillo, L.↗
Combining variational autoencoders and physical bias for improved microscopy data analysis *
Electron and scanning probe microscopy produce vast amounts of data in the form of images or hyperspectral data, such as electron energy loss spectroscopy or 4D scanning transmission electron microscope, that contain information on a wide range of structural, physical, and chemical properties of materials. To extract valuable insights from these data, it is crucial to identify physically separate regions in the data, such as phases, ferroic variants, and boundaries between them. In order to derive an easily interpretable feature analysis, combining with well-defined boundaries in a principled and unsupervised manner, here we present a physics augmented machine learning method which combines the capability of variational autoencoders to disentangle factors of variability within the data and the physics driven loss function that seeks to minimize the total length of the discontinuities in images corresponding to latent representations. Our method is applied to various materials, including NiO-LSMO, BiFeO 3 , and graphene. The results demonstrate the effectiveness of our approach in extracting meaningful information from large volumes of imaging data. The customized codes of the required functions and classes to develop phyVAE is available at https://github.com/arpanbiswas52/phy-VAE.
97 MATHEMATICS AND COMPUTING↗
Through-thickness recrystallization characteristics of a laminated AA3xxx–AA6xxx aluminum alloy system
The through-thickness annealing behavior of a laminated AA3xxx–AA6xxx alloy system at 300 °C has been studied by scanning electron microscopy, electron backscatter diffraction analysis, electron probe micro-analysis, differential scanning calorimetry, and hardness measurement. Results show that the recrystallization process starts at the interface region between the AA3xxx (clad) and AA6xxx (core) layers. Subsequently, the recrystallization process front progresses into the core layer, while the clad layer is the last region to recrystallize. It is also found that precipitation precedes recrystallization in the entire laminate at the investigated temperature. The preferential onset of recrystallization at the interface region is attributed to the net driving pressure being the highest in this region. The factors that lead to such enhanced net driving pressure are (a) deformation incompatibility between the two alloy layers, (b) lower solute content of the interface, which also leads to lower volume fraction of precipitates, and (c) an accelerated rate of precipitate coarsening due to the presence of a higher density of dislocations. The gradual progress of recrystallization from the interface towards the core layer is dictated by precipitate coarsening and the dependence of its rate on the density of deformation-induced dislocations. The lower driving pressure due to lower work hardening capacity, high solute drag pressure due to Mn, and additional Zener drag from precipitates that form due to solute redistribution during annealing explain the late initiation of recrystallization in the clad layer. - Highlights: • The through-thickness recrystallization of a laminated system is investigated. • The early onset of recrystallization at the interface is discussed. • The effects of precipitation and coarsening on recrystallization are analyzed.
36 MATERIALS SCIENCE↗
Electron microprobe analysis of trace elements in minerals at 10 PPM concentrations
An improved technique is developed for measuring backgrounds during trace element analysis of crystals and glass using electron microprobes. This technique overcomes major difficulties encountered with conventional techniques, such as the problem of obtaining the net X-ray intensity of the characteristic emission line of interest with sufficient precision and accuracy, as well as the error due to the inability to directly measure the intensity at the wavelength of the characteristic line on the sample being analyzed. It is shown that this technique can yield reproducible results to within 4 ppm in olivine, and has a minimum uncertainty and detection limit of 10 ppm Nd in olivine.
Mckay, G. A.↗
Germination, growth rates, and electron microscope analysis of tomato seeds flown on the LDEF
The tomato seeds were flown in orbit aboard the Long Duration Exposure Facility (LDEF) for nearly six years. During this time, the tomato seeds received an abundant exposure to cosmic radiation and solar wind. Upon the return of the LDEF to earth, the seeds were distributed throughout the United States and 30 foreign countries for analysis. The purpose of the experiment was to determine the long term effect of cosmic rays on living tissue. Our university analysis included germination and growth rates as well as Scanning Electron Microscopy and X-ray analysis of the control as well as Space-exposed tomato seeds. In analyzing the seeds under the Electron Microscope, usual observations were performed on the nutritional and epidermis layer of the seed. These layers appeared to be more porous in the Space-exposed seeds than on the Earth-based control seeds. This unusual characteristic may explain the increases in the space seeds growth pattern. (Several test results show that the Space-exposed seeds germinate sooner than the Earth-Based seeds. Also, the Space-exposed seeds grew at a faster rate). The porous nutritional region may allow the seeds to receive necessary nutrients and liquids more readily, thus enabling the plant to grow at a faster rate. Roots, leaves and stems were cut into small sections and mounted. After sputter coating the specimens with Argon/Gold Palladium Plasma, they were ready to be viewed under the Electron Microscope. Many micrographs were taken. The X-ray analysis displayed possible identifications of calcium, potassium, chlorine, copper, aluminum, silicon, phosphate, carbon, and sometimes sulfur and iron. The highest concentrations were shown in potassium and calcium. The Space-exposed specimens displayed a high concentration of copper and calcium in the two specimens. There was a significantly high concentration of copper in the Earth-based specimens, whereas there was no copper in the Space-exposed specimens.
Hammond, Ernest C., Jr.↗
Scanning transmission electron microscopy analysis of Ge(O)/(graphitic carbon nitride) nanocomposite powder
Analytical electron microscopy has revealed the structure of particles that were synthesized by chemical reaction of GeO{sub 2} with NaBH{sub 4} in the basic solution including graphitic carbon nitride (g-C{sub 3}N{sub 4}) powders. The g-C{sub 3}N{sub 4} was arranged by recrystallization of melamine at 600 °C under N{sub 2} gas atmosphere. The samples were dried at 60 °C or 180 °C for 4 h. The g-C{sub 3}N{sub 4} was observed as lamellae of several ten nm or less in size and had an amorphous-like structure with a distorted lattice in an area as small as a few hundred pm in size. The reaction product was Ge(O) particles as fine as several nm in size and composed of Ge and O atoms. Most of the particles must be of GeO{sub 2−x} with the amorphous-like structure that has also a distorted lattice in an area of a few hundred pm in size. In the sample dried at 60 °C, the particles were found to be dispersed in a wide area on the g-C{sub 3}N{sub 4} lamella. It is hard to recognize those particles in TEM images. The particles in the sample dried at 180 °C became larger and were easily observed as isolated lumps. Hence, these powders can be regarded as GeO{sub 2}/g-C{sub 3}N{sub 4} or Ge/GeO{sub 2}/g-C{sub 3}N{sub 4} nanocomposites, and expected to be applicable to anode materials for high energy Li-ion batteries due to Ge catalysis effect, accordingly. - Graphical abstract: STEM analysis of Ge(O)/(graphitic carbon nitride) nanocomposite powder. - Highlights: • Graphitic (g)-C{sub 3}N{sub 4} powder was prepared at 600 °C by recrystallization of melamine. • Ge(O) was prepared by chemical reaction in a solution including the g-C{sub 3}N{sub 4} powders. • The products can be regarded as GeO{sub 2}/g-C{sub 3}N{sub 4} or Ge/GeO{sub 2}/g-C{sub 3}N{sub 4} nanocomposites. • GeO{sub 2} was amorphous several-nm particles and g-C{sub 3}N{sub 4} was amorphous lamella of several 10 nm in size. • We expect them to be applicable for high energy Li-ion battery anode materials.
36 MATERIALS SCIENCE↗
Investigation into Texture and Structure of MA2-1PCh Magnesium Alloy after Equal Channel Angular Extrusion and Annealing by Quantitative X-Ray Texture Analysis and Electron Backscatter Diffraction
This article discusses application of quantitative X-ray texture analysis (QTXA) based on measurement of direct pole figures and electron backscatter diffraction (EBSD) aimed at study of peculiarities of formation of texture and structure of MA2-1pch magnesium alloy after equal channel angular extrusion (ECAE) and subsequent annealing. Shear bands with the width of 60 μm oriented at 45°–50° to the extrusion direction are revealed, where an inclined scattered basis texture is detected, and outside of these bands, a prismatic texture. As a consequence, basic sliding is activated in the shear bands, which is confirmed by the distribution of Schmid factors. The influence of texture and orientation of shear bands on anisotropy of strength mechanical properties of alloy is discussed.
36 MATERIALS SCIENCE↗
Summary of ISO/TC 201 Standard: ISO 29081: 2010, Surface Chemical Analysis - Auger Electron Spectroscopy - Reporting of Methods Used for Charge Control and Charge Correction
This international standard specifies the minimum amount of information required for describing the methods of charge control in measurements of Auger electron transitions from insulating specimens by electron-stimulated Auger electron spectroscopy to be reported with the analytical results. Information is provided in an Annex on methods that have been found useful for charge control prior to or during AES analysis. The Annex also includes a summary table of methods or approaches, ordered by simplicity of approach. A similar international standard has been published for x-ray photoelectron spectroscopy (ISO 19318: 2003(E), Surface chemical analysis - X-ray photoelectron spectroscopy - Reporting of methods used for charge control and charge correction).
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Multi defect detection and analysis of electron microscopy images with deep learning
Electron microscopy is widely used to explore defects in crystal structures, but human detecting of defects is often time-consuming, error-prone, and unreliable, and is not scalable to large numbers of images or real-time analysis. In this work, we discuss the application of machine learning approaches to find the location and geometry of different defect clusters in irradiated steels. We show that a deep learning based Faster R-CNN analysis system has a performance comparable to human analysis with relatively small training data sets. Furthermore, this study proves the promising ability to apply deep learning to assist the development of automated microscopy data analysis even when multiple features are present and paves the way for fast, scalable, and reliable analysis systems for massive amounts of modern electron microscopy data.
36 MATERIALS SCIENCE↗
Numerical Analysis of Electron Runaway in the Presence of Enhanced Field in the Vicinity of a Microtip
Transition of field-emission electrons to the runaway regime in the region of enhanced electric field determined by the configuration of a microtip on a cathode is studied at several pressures of gas medium. The problem is solved using simulation of electron motion in the presence of nonuniform electric field with the aid of the Monte Carlo procedure in the 2D configuration. Nitrogen is used as a working gas. Passage through a relatively small region of the enhanced field in the vicinity of the microtip may substantially facilitate electron escape to the runaway regime, especially, at pressures of greater than 10 atm. In our opinion, the resulting runaway electrons may provide preionization of gas medium and formation of the initial stage of a 3D discharge.
70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
First Results of $\nu_e$ Appearance Analysis and Electron Neutrino Identification at NOvA
NOvA is a long-baseline accelerator-based neutrino oscillation experiment that is optimized for $\nu_\mu\to\nu_e$ measurements. It uses the upgraded NuMI beam from Fermilab and measures electron-neutrino appearance and muon-neutrino disappearance at its Far Detector in Ash River, Minnesota. The $\nu_e$ appearance analysis at NOvA aims to resolve the neutrino mass hierarchy problem and to constrain the CP-violating phase. The first data set of $2.74\times10^{20}$ protons on target (POT) equivalent exposure taken by NOvA has been analyzed. The first measurement of electron-neutrino appearance in NOvA provides solid evidence of $\nu_\mu\to\nu_e$ oscillation with the NuMI beam line. Electron-neutrino identification is the key ingredient for the $\nu_e$ appearance analysis. The electron-identification algorithm used to produce the primary results presented here compares 3-D shower-energy profiles with Monte Carlo prototypes to construct likelihoods for each particle hypothesis. Particle likelihoods, among other event-topology variables, are used as inputs to an Artificial Neural Network for the final electron-neutrino identification. The design and implementation of this algorithm is also presented.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Low keV electron probe analysis of silicate minerals for Mg, Al, and Si using pure-element standards
Accurate electron probe values for Mg, Al, and Si in silicate minerals may be obtained with pure-element standards. Analysis must be done at low (6 kV) accelerating potential and for best results, the average atomic number of the sample should be within about plus or minus 1 of the atomic number of the pure-element standard. This last requirement is automatically fulfilled for most common silicate minerals, as their average atomic numbers usually fall within the 11 to 15 range. Examples studied include a wet-chemically analyzed cordierite containing 17.71 weight percent Al, for which a value of 17.6 plus or minus 0.3 percent was obtained with the electron probe, and a hornblende containing 19.15 percent Si, which gave 19.0 plus or minus 0.3 percent using the probe method.
Cunningham, G. G.↗