bluuebunny/crossref_metadata_2025_split huggingface dataset:
Image Simulation of Small Pt Particles and its Application to Lattice Spacing Measurements in Catalysts
Authors: Tsen S-C Y , Crazier P A , López Cartes C , Liu J , Calvino JJ 
Published: July 2020

Abstract
The technique of high resolution imaging is important for characterizing the structure of small metal particle catalysts and nanophase materials. For bimetallic systems, it is possible to use local lattice parameter measurements to identify alloy compositions in ensembles of nanometer sized metal particles [1]. However, determining alloy composition is challenging because changes in lattice parameters of only a few percent must be reliably detected. We have performed measurements of the apparent d(111) fringe spacing on both simulated and experimental HREM images from Pt particles in the size range 15 - 35 Å. A series of initial image simulations of Pt cubeoctahedrons with 17 Å (201 atoms) and 34 Å (1289 atoms) in diameter have been studied in order to understand the effect of different parameters on the accuracy of lattice spacing. The clusters were built using the Rhodius program developed by Botana et al [2]. Starting with a bulk crystal we create cubeoctahedra by applying successive cuts along either the (111) or (100) direction. A supercell size of 50Å was selected and the particles were oriented at or close to the [110]. Images were calculated by the multi-slice techniques using both the CERIUS and EMS applications. The supercell was divided into 20 slices and the following parameters were used in the calculation Eo = 400 kV, Cs = 1mm, Δf= -320 Å, focal spread = 80 Å, convergence = 0.5 mrad and atomic vibration = 0.35Å.
A UHV Diffraction Camera With Energy Filter for Convergent Beam RHEED and TED.
Authors: Weierstall U , Zuo JM , Kjørsvikf T , Spence JCH 
Published: July 2020

Abstract
A UHV diffraction camera has been built which can be used in either transmission or reflection mode. Fig. 1 shows a schematic view of the instrument. The optical axis of the instrument is vertical, with gun below and a downward-looking CCD camera on top. The pressure with gun operating is 1×10−10 Torr. An ion pump and oil-free turbo system is used. The electron gun is a fully bakeable custom UHV RHEED gun with LaB emitter and two magnetic lenses. This allows the beam to be focused to an area of about 1 micron on the surface of the sample. The gun works in the energy range of l-50keV. A double tilt stage, with sample exchange, has been built which allows azimuth rotation by 360° and tilt by ° 15°. The sample can be resistively heated on the stage up to 1300°C. The sample holder can also be used with 3mm diameter TEM grids for transmission diffraction. An external lens-coupled liquid-nitrogen cooled Princeton CCD camera with 1024×1024 pixels is used for image acquisition, viewing a transmission phosphor through a lead-glass window.
The energy filter consists of three spherical grids serving as a retarding field energy filter. The design is similar to that of Horio [1]. The first and last grids are grounded, while the center grid holds the retarding voltage. High voltage stability up to 10kV has been achieved with this filter. Fig. 2 shows an energy loss spectrum obtained.from the specular spot of the Si(111) surface. The spectrum was obtained from the measured integrated intensities by numerical differentiation.
CBED Investigations of Mesoscopic Semiconductor Structures
Authors: Lakner H , Schulze-Kraasch F , Mendorf C , Brockt G 
Published: July 2020

Abstract
Ternary and quaternary heterostructures from III-V-semiconductors get more and more importance in the fabrication of high-speed/high frequency devices in telecommunication systems. One of the key parameters for the performance of such devices is the crystalline quality and especially the amount of tetragonal distortion in strained layers on a nanometer scale. Strain can cause problems for the growth of such layers like relaxation induced defects, especially for the case of a high value of lattice mismatch. However, strain and the associated influence on the band structure can be used consciously for the design of tailor-made heterostructures (band gap engineering). Therefore, the spatially resolved investigation of local crystal properties (tetragonal distortion or strain and strain relaxation) is a key tool for the characterization of strained layers.
Convergent beam electron diffraction (CBED) patterns and convergent beam imaging (CBIM) can be used to evaluate informations on the local crystalline structure. E.g. the position of the High Order Laue Zone (HOLZ) lines in the CBED patterns is sensitive to the local strain and therefore can be used to determine strain and relaxation effects in heterostructures quantitatively. But in practice the applicability of CBED is often limited by a lack of ultimate spatial resolution and/or of sensitivity.
Investigation of Low Symmetry Crystals Using Elctron Backscatter Diffraction
Authors: Dingley DJ 
Published: July 2020

Abstract
Electron backscatter diffraction patterns obtained from low symmetry crystals can present difficulties for automated pattern recognition. For example, when only a single zone axis is observed in the diffraction pattern and the Kikuchi bands used for indexing all pass through the zone axis then only two-dimensional crystallographic information is obtained. This results in there being a 180 degree ambiguity in the measured orientation. Furthermore, it is often observed that in automated indexing of quartz, an additional ambiguity is introduced when the zone axis imaged is [0001]. In this case it is difficult to distinguish between the true orientation and it’s twin. This ambiguity is overcome only if Kikuchi bands from the upper Laue zones are used in the indexing. However, in automated indexing it is normal for the computer to select the strongest Kikuchi bands visible and these will not be those from the upper Laue zones when the [0001] zone axis is imaged. This and other pseudo symmetries have been observed and have been overcome by applying correction procedures during data collection and in post collection analysis.
Phase Identification of Individual Particles by Electron Backscatter Diffraction (EBSD)
Authors: Small J , Michael J 
Published: July 2020

Abstract
Backscattered electron Kikuchi patterns (BEKP) were first observed by Alam et al. in 1954. J.A. Venables and C.J. Harland made the initial observation of BEKP and in the scanning electron microscope in 1973. In 1996, Goehner and Michael developed an electron backscatter diffraction (EBSD) system that uses a 1024 × 1024 pixel CCD camera coupled to a thin scintillator rather than photographic film. In their system, the quality of the raw patterns is improved by the use of “flat fielding” which normalizes the raw image to a “flat field” reference image that contains the image artifacts, including background, but not the crystallographic information. Automated pattern analysis is carried out using a Hough transform to locate bands and band edges in the pattern. The resulting crystallographic information is coupled with the elemental information from energy or wavelength dispersive x-ray spectrometry and the phase is identified is made through a link to a database such as the Powder Diffraction Files published by ICDD. An indexed pattern of the suspected phase is then synthesized for comparison to the unknown. This system is marketed commercially by Noran Instruments and offers the first practical method for rapid identification of unknown crystallographic phases in the SEM.
EBSD With FEGSEM - Issues, Advances and Applications
Authors: Humphreys FJ , Brough I 
Published: July 2020

Abstract
A standard commercial EBSD system, comprising a CCD camera (Nordif) and acquisition software (HKL Technology) has been interfaced to a Philips XL30 FEGSEM, and the spatial and angular resolutions for EBSD compared with a conventional W-filament JEOL 6300 SEM equipped with a similar EBSD system.
In characterising a grain or subgrain structure, overlapping diffraction patterns are obtained at the boundaries, and the effective spatial resolution can be defined as the distance over which the patterns cannot be solved. The spatial resolution is best in the direction parallel to the specimen tilt axis (LA), typically some three times better than for the direction perpendicular to the axis. The resolution is conveniently determined by measuring the fraction of patterns which are solved (Ns) during a raster scan of the sample. For a microstructure of equiaxed grains of size D, LA is given approximately by D(1-Ns)/4. Figure 1 is a plot of Ns against D−1 for aluminium samples under optimum operating conditions, and it is seen that the spatial resolution in the FEGSEM is some three times better than in the W-filament SEM.
The effect of beam current on LA is shown in figure 2. For the W-filament SEM, LA is a strong function of the probe current.
Adaptive Orientation Imaging Microscopy
Authors: Yang W , Wu C-T , Adams BL , De Graef M 
Published: July 2020

Abstract
This paper describes a new form of orientation imaging microscopy: Adaptive Orientation Imaging Microscopy or AOIM. In standard OIM experiments the local orientation of the crystal lattice is determined with respect to a suitable reference frame by acquiring and indexing electron back-scattering (EBS) patterns on a square or hexagonal grid of sampling points. Since its invention, OIM has been extensively used to characterize polycrystalline materials. With the fast development of computers and CCD camera systems in the past few years, the standard OIM can now acquire and index of the order of 4000 EBS patterns per hour.
In a typical OIM experiment one is usually interested in either the overall texture of. the sample, or in the types and relative frequencies of grain boundaries. In the former case the proper way of acquiring orientation data involves the use of an equidistant grid of sampling points. In the latter case, however, a large fraction of the acquisition time is wasted sampling the grain interior, which does not provide any information about the grain boundaries.
Choosing an Electron Backscattering Pattern (EBSP) System.
Authors: Eades Alwyn 
Published: July 2020

Abstract
Recent advances in cameras and computers have made it possible to build electron backscattering pattern (EBSP) cameras which can give crystallographic information from diffraction patterns in the scanning electron microscope (SEM) on a routine basis.[1] There are a few hundred such systems world wide and the number is growing fast. In the case of crystalline samples (nearly all applications of SEM outside the biomedical field), it will surely soon be considered essential to fit an SEM with an EBSP system, just as it is now considered essential to have the SEM equipped with an energy-dispersive x-ray spectroscopy (EDS) system. There are at least four commercial manufacturers of EBSP systems. In the next few years, then, I anticipate that many owners of existing SEMs as well as buyers of new instruments will be faced with the problem of selecting an EBSP system. This paper presents some of the issues involved in making such a choice.
As in many technical decisions, different people will have different needs and put different priorities on the specifications to be met. An instrument which is to be used to do repeated analyses of aluminum for beer cans will have different needs from a system used mostly to teach crystallography, and those will be different in turn from the needs of a system used to determine which phases are present in geological samples.
Crystallographic Characterization of Sputter Deposited Nb-Cu Thin Films Using Electron Backscatter Diffracted Patterns.
Authors: Loloee R , Pratt WP , Crimp M A 
Published: July 2020

Abstract
Crystallographic structure plays an important role in determining the fundamental physical properties of metallic thin films and superlattices, and structural characterization of such films is crucial for furthering the application of these materials [1]. Epitaxial films are usually characterized using a wide range of techniques including x-ray diffraction, REED, neutron diffraction, and highresolution electron microscopy. A complementary approach is electron backscatter patterns (EBSP), which is an SEM technique that can be used to measure crystallographic orientations of single or polycrystals [2].
In this work, EBSPs have been used to characterize the crystallite size and orientation of sputterdeposited Cu films. The EBSPs were formed in a CamScan 44FE SEM and recorded using an ORTEX CCD camera system. The images were analyzed using the Channel+ software package, and orientation maps were plotted using Channel+Ice [3].
Comparison of Environmental Secondary Electron Detector
(ESD) Imaging and Electron Diffraction Mapping of a Nickel Tape Using the Environmental Scanning Electron Microscope (ESEM)
Authors: Goddard R E , Hascicek Y S 
Published: July 2020

Abstract
A relationship between the local microstructure (crystallographic orientation) of a sample and an image from a scanning electron microscope (SEM) has been an elusive goal. Being able to show the structure from an exact area and relate it to other data is essential to the understanding of the structure relationship to the entire sample. Conventionally microtextural information of tapes is obtained by using x-ray diffraction and pole figures. But this only provides information about the global texture. The precise location is not well defined. The ability to physically transfer the sample from the x-ray diffractometer to a SEM and accurately state that this is the same area has been impossible. Electron Backscatter Diffraction Patterns (EBSPs) have been obtained in an electron microscope and the exact area in relation to the rest of the sample is determined. Thus larger areas can be defined and put together to form a composite of an entire sample. This, however, may be hard to accomplish in that defined areas for the image scan may be at a different scale than the EBSP scan. A contrast method of imaging in the ESEM using an increased vacuum and the ESD yields a good correlation to mapped areas obtained from EBSPs or also known as backscatter electron Kikuchi diffraction patterns (BEKPs or BKPs).
Recent Advances in Gaseous Detection Modes in the ESEM
Authors: Hardt T A , Knowles W R 
Published: July 2020

Abstract
The Environmental Scanning Electron Microscope, or ESEM, is the only class of SEM that can image in a gaseous environment that will maintain a sample in a fully wet state. The use of the patented Gaseous Secondary Electron Detector, or GSED, which amplifies the secondary electron signal with the gas, has allowed the ESEM to image a multitude of samples with true secondary contrast. Recently, several new modes of imaging in a gas have been developed and will allow further expansion of the capabilities of the ESEM.
To maintain pressures in the ESEM up to 20 Torr (27 mbar), the use of multiple, differentially pumped apertures, is required. This can place a restriction on the low magnification range. In the large field detection mode, all magnification restrictions are removed. Magnifications as low as lOx may be achieved. This is similar to many conventional SEMs.
Spatial Correlation of Elemental Impurities and Charge Contrast Image Detail in Gibbsite
Authors: Baroni Travis C , Griffin Brendan J , Lincoln Frank J 
Published: July 2020

Abstract
Charge Contrast Imaging (CCI), is a recently reported technique allowing the imaging of the internal microstructure of non and poorly conductive materials. In previous work, the relationship between controlled growth events in batch-precipitated gibbsite, Al(OH)3 and the appearance of contrasting bands in CCIs has been empirically correlated. The data presented was spatial, based on the number and dimensions of growth rings, however no interpretation of the contrast variation was made. Suggestions that the contrast may be related to charge trapping, which in turn is related to conductivity pathways and impurity concentrations indicates that the technique may provide insight into crystallisation processes. The current work examines the spatial distribution of impurity elements and their effect on the contrast observed within growth layers in charge contrast images of gibbsite.
Analyses for Ca, Fe and Si, the main impurities in the solutions before and after precipitation indicate a preferential partitioning of Ca and to a lesser extent Si and Fe into gibbsite.
Irradiation Induced Effects in the Environmental Scanning Electron Microscope
Authors: Stevens Kalceff Marion A 
Published: July 2020

Abstract
When a poorly conducting specimen is irradiated with an electron beam in a variable pressure electron microscope, the excess charge on the surface of the specimen can be neutralized by incident gas ions to prevent deflection and retarding of the electron beam. A small fraction (&lt;10∼6) of the incident electrons are trapped at irradiation induced or pre-existing defects within the irradiated micro-volume of specimen. The trapped charge induces an electric field, which may result in the electro-migration and micro-segregation of charged mobile defect species within the irradiated volume of specimen. These charge induced effects are dependent on the density of trapping centers and their capture cross sections. In particular, evidence of these micro-diffusion processes can be directly observed in electron beam irradiated ultra pure silicon dioxide (SiO2) polymorphs using Cathodoluminescence (CL) microanalysis (spectroscopy and imaging). CL microanalysis enables both pre-existing and irradiation induced defects in wide band gap materials (i.e. semiconductors and insulators) to be monitored and characterized with high sensitivity and spatial resolution. Depth resolution is achieved by varying the electron beam energy.
Advances in Environmental Scanning Electron Microscopy: Semiconductor/Thin Fim Applications, Cathodoluminescence (CL) Spectroscopy, and Detector Quantum Efficiency (DQE) Comparisons.
Authors: Griffin Brendan J , Browne James R , Drouin Dominique , Scharf David 
Published: July 2020

Abstract
Charge Contrast Imaging (CCI) in the environmental scanning electron microscope (ESEM) has rapidly evolved to an important imaging technique for a range of materials. The investigation of the applicability of CCI to the examination of semiconductor and thin film (MCT) samples and devices has been highly successful. Dopant concentration and depth can be differentiated, as has been noted for variable pressure SEM. Quantification of concentration remains difficult due to the complexity of variables controlling CCI but should be achievable in the near future. The extreme sensitivity to surface contaminants previously noted on polished diamond surfaces is also seen on silicon. Monte Carlo modelling of this contrast indicates, for the examined materials, an information depth of a few nanometres for CCI, whilst using 30kV accelerating voltage. The modelling shows that CCI is capable of routine detection of contaminant layers on silicon at the nanometre scale. These results also provide the first data confirming initial suggestions that CCI is derived from the near-surface regions of the sample.
CCI examination of mercury cadmium telluride (MCT) devices has also provided images with new detail. This detail is currently being interpreted. Initial examination suggests an influence of the substrate on film growth (figure 1). Unusual corner structures are visible around the mask region.
Environmental SEM in a Multi-User Biological Sciences E.M. Unit
Authors: Gilpin Christopher J , Baguneid Mohamed S 
Published: July 2020

Abstract
Environmental scanning electron microscopy (ESEM) has matured into a mainstream technique in many areas of microscopy. Instrumentation has evolved and our understanding of some of the imaging mechanisms has progressed. However the majority of laboratories where ESEMs are located are based around the materials sciences. Despite the fact that ESEM is the only SEM instrument that permits liquid water to be present whilst imaging, the housing of such a microscope in biological EM units has been relatively rare. This authors laboratory is a multi-user EM unit based in a School of Biological Sciences. There exists the opportunity for basic biological scientists, clinical and pre-clinical medical and dental researchers to make use of such a resource. Indeed as the ESEM is housed alongside a conventional high vacuum instrument and a cryo high vacuum instrument there exists the ideal opportunity to carry out comparative studies.
This study will examine a range of biological samples using ESEM, cryo SEM and dry high vacuum SEM.
Evaluation of the Variable Pressure Correction Technique for X-ray Microanalysis in the ESEM
Authors: Carlton R A , Lyman C E , Roberts J E 
Published: July 2020

Abstract
The purpose of this study is to evaluate the variable pressure correction technique (VPCT) as a solution to the problem of extraneous x-ray peaks due to electron beam broadening in the chamber gas of the ESEM. The basis of VPCT is the observation that target x-ray counts decrease with increasing chamber pressure; whereas, x-ray counts due to beam broadening increase. If data are collected at two or more chamber pressures, the number of x-ray counts for an element can be corrected to that expected at zero gas pressure (high vacuum). Tests of NIST SRM 482 have shown EDS x-ray analysis in the ESEM (within the chamber pressure range of 1 to 8 torr) to have comparable accuracy and precision values to those of EDS in the traditional SEM. The samples used in the these studies, however, were quite large (ca. 500 μm in diameter) and so extraneous EDS peaks, due to the electron beam broadening effect of the chamber gas, were minimized.
The 60% Au / 40% Cu wire of SRM 482 was pressed into a hole in the surface of an Al specimen stub so as to produce a flat surface with a sharp interface between the wire and the stub. Spectra were collected at 5 and 150 μm from the junction of the wire and the Al stub at chamber pressures of 2, 4, and 8 torr.
The Computation of the Skirt in VP-SEM OR ESEM With Monte Carlo Simulations
Authors: Gauvin Raynald 
Published: July 2020

Abstract
It is well known that the interaction of the electron beam with the gas in the VP-SEM or ESEM generate the so-called skirt as a result of the elastic collisions between the electrons and the molecules. Since the electrons in the skirt hit the specimen far away from the electron beam, they degrade the resolution of the analyses performed in the VPSEM or ESEM. However, the magnitude and the shape of the skirt are still a matter of controversy despite the fundamental importance of knowing these two factors. In this context, a Monte Carlo program has been developed to simulate the interaction of the electron beam with a gas as a function of the gas composition, gas pressure, electron beam energy and working distance (in reality, we should talk of the total distance traveled by the electron beam in the gas). This Monte Carlo program used a single scattering approach considering elastic collisions only since energy loss is negligible owing to the low density of the gas. 10 millions electron trajectories have been simulated for each conditions.