of carbon monoxide on nanoscale facets. Aberration-corrected scanning transmission electron microscopy techniques have been used to elucidate the atomic structures of the active...
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At present transmission electron energy loss spectrum (EELS) analysis is only carried out in dedicated research instruments such as transmission electron microscopes (TEMs) or scanning transmission electron microscopes. This article presents a new design of second-order geometric aberration ...
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with transmission electron microscopes (- familiarity with aberration corrected scanning transmission electron-corrected analytical electron microscopes. It is also the home of the world�renowned Lehigh Microscopy SchoolRESEARCH ENGINEER IN ADVANCED ANALYTICAL ELECTRON MICROSCOPY Department ...
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Scanning confocal electron microscopy (SCEM) is a new imaging mode in electron microscopy. Spherical aberration corrected electron microscope instruments fitted with two aberration correctors can be used in this mode which provides improved depth resolution and selectivity compared to optical sectioning in a conventional ...
NASA Astrophysics Data System (ADS)
Recent instrumental developments have enabled greatly improved resolution of scanning transmission electron microscopes (STEM) through aberration correction. An additional and previously unanticipated advantage of aberration correction is the greatly improved depth ...
A domestic spherical aberration corrected 300 kV transmission electron microscope named R005, which stands for 0.05 nm resolution, was developed. It has double aberration correctors in probe-forming and image-forming systems for high-resolution scanning transmission electron microscope (STEM) ...
Mapping of Phase Segregation at CMR Grain Boundaries in the Scanning Transmission Electron Microscope "The in the Scanning Transmission Electron Microscope M. Varela*, V. Pe�a**, Z. Sefrioui**, A. R. Lupini*, J. Aberration correction in the Scanning ...
The authors demonstrate that confocal imaging trajectories can be established in a transmission electron microscope fitted with two spherical aberration correctors. An atomic-scale electron beam, focused by aberration-corrected illumination optics, is directly imaged by a second aberration-corrected system. The initial experiment described indicates how ...
We visualized lithium atom columns in LiV?O? crystals by combining scanning transmission electron microscopy with annular bright field (ABF) imaging using a spherical aberration-corrected electron microscope (R005) viewed from the [110] direction. The incident electron beam was coherent with a convergent angle of 30 mrad (semi-angle), ...
PubMed
Direct atomic displacement mapping at ferroelectric interfaces by aberration corrected scanning transmission electron microscopy(STEM) (a-STEM image, b-corresponding displacement profile) is combined with Landau-Ginsburg-Devonshire theory to obtain the complete interface electrostatics in real space, including ...
This paper presents our recent progress on the application of reconfigurable logic technology to intelligent human sensing. First, hardware specialization technique is presented to realize small and fast preprocessor based on reconfigurable logic devices. Second, a load balancing technique for heterogeneous systems is introduced. Then, a real-time aberration ...
-tunable optical and electronic properties for applications in photo- voltaics,1-3 photocatalysis,4-7 bioassays,3: RBS data used to calculate the ratio of Cd to Se for the HDA CdSe nano- crystals. This material subtle details about the shape and faceting of nano- crystals with near sub-angstrom precision
Inclusion of spatial incoherence has been shown to give quantitative agreement between non-aberration-corrected high-angle annular dark-field scanning transmission electron microscopy images and theoretical simulations. Here we show that, using the same approach, a significant improvement in the correlation between calculated and ...
Inclusion of spatial incoherence has been shown to give quantitative agreement between non-aberration-corrected high-angle annular dark-field scanning transmission electron microscopy images and theoretical simulations. Here we show the same approach is valid for aberration-corrected probes, by fitting theoretical and experimental ...
Transition metal chalcogenides like MoS2 or WS2 are quasi-two dimensional (2D) compounds. Similar to carbon, transitional metal chalcogenides also form close caged structures known as inorganic fullerenes (IF) and nanotubes (INTs). We have sought to use probe aberration corrected electron microscopy for elucidating some important features and aspects of ...
Future aberration corrected transmission electron microscopes (TEM) will have a strong impact in materials science, since such microscopes yield information on chemical bonding and structure of interfaces, grain boundaries and lattice defects at an atomic level. Beyond this aberration ...
In order to understand the mechanism of Cu clustering and Ni effects on Cu clusters, a sub-nano scale structural and elemental analysis of Cu-bearing steels was carried out through an aberration corrected scanning transmission electron microscope. Based on systematic observation condition adjustment by changing the ...
The Transmission Electron Aberration-corrected Microscope (TEAM) Project For the past several years, five DOE-supported electron beam microscopy efforts, located at Argonne...
The ability to correct the aberrations of the probe-forming lens in the scanning transmission electron microscope provides not only a significant improvement in transverse resolution but in addition brings depth resolution at the nanometer scale. Aberration correction therefore opens up the possibility of 3D ...
Vacancies (VCu, VIn) and substitutional atoms (InCu, CuIn) in CuInSe2 crystal, which is the key semiconductor material for thin film solar cell applications, were directly observed by 300kV aberration-corrected high angle annular dark field scanning transmission electron microscope (HAADF-STEM). The atomic columns of Cu, In and Se were ...
Aberration-corrected scanning transmission electron microscopes (STEMs) provide sub-Angstrom lateral resolution; however, the large convergence angle greatly reduces the depth of field. For microscopes with a small depth of field, information outside of the focal plane quickly becomes blurred and less defined. It may not be possible to ...
Aberration corrected electron optics allow routine acquisition of high-spatial resolution spectroscopic images in the scanning transmission electron microscope, which is important when trying to understand the physics of transition metal oxides such as manganites. The physical properties of these perovskites are ...
The resolution of electron energy loss spectroscopy (EELS) is limited by delocalization of inelastic electron scattering rather than probe size in an aberration corrected scanning transmission electron microscope (STEM). In this study, we present an experimental quantification of EELS spatial resolution using ...
The technique of X-ray energy dispersive spectroscopy (XEDS) spectrum imaging in a dedicated scanning transmission electron microscope (STEM) is discussed in relation to its applicability to bimetallic nanoparticles. It is shown that the recent availability of aberration corrected microscopes and multivariate ...
We show in this article that it is possible to obtain elemental compositional maps and profiles with atomic-column resolution across an InxGa1-xAs multilayer structure from 5th-order aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) images. The compositional profiles obtained from ...
Aberration-corrected Z-contrast scanning transmission electron microscopy of core/shell nanocrystals shows clear correlations between structure and quantum efficiency. Uniform shell coverage is obtained only for a graded CdS/ZnS shell material and is found to be critical to achieving near 100% quantum yield. The sublattice sensitivity ...
Electron energy loss (EEL) spectroscopy and high angle annular dark field (HAADF) imaging in aberration-corrected electron microscopes are powerful techniques to determine the chemical composition and structure of materials at atomic resolution. We have implemented Smart Acquisition, a flexible system of scanning transmission electron microsocpy (STEM) ...
We have successfully developed a spherical aberration (Cs)-corrected electron microscope for probe- and image-forming systems using hexapole correctors. The performance of the microscope has been evaluated experimentally. The point resolution attained using the image-forming Cs-corrector is better than 0.12 nm. For scanning transmission electron ...
Recent and ongoing improvements in aberration correction have opened up the possibility of depth sectioning samples using the scanning transmission electron microscope in a fashion similar to the confocal scanning optical microscope. We explore questions of principle relating to image ...
TEAM on TV The TEAM Project (Transmission Electron Aberration-Corrected Microscope) Recent Publications from TEAM Why What Who How When and Where DOE In December 1959, physicist...
The successful correction of third-order and, more recently, fifth-order aberrations has enormously enhanced the capabilities of the scanning transmission electron microscope (STEM), by not only achieving record resolution, but also allowing near 100% efficiency for electron energy loss spectroscopy, and higher currents for two-dimensional spectrum ...
Silicon nitride membranes can be used for windows of environmental chambers for in situ electron microscopy. We report that aberration corrected scanning transmission electron microscopy (STEM) achieved atomic resolution on gold nanoparticles placed on both sides of a 50-nm-thick silicon nitride membrane at 200 keV ...
The "delocalization" of inelastic scattering is an important issue for the ultimate spatial resolution of innershell spectroscopy in the electron microscope. It is demonstrated in a nonlocal model for electron energy loss spectroscopy (EELS) that delocalization of scanning transmission electron microscopy (STEM) images for single, isolated atoms is ...
In this paper we report the use of adaptive optics to correct for sample induced aberrations in optical microscopy, crucially comparing individual pixel-by-pixel correction against a single correction for an entire optical section. Sample induced optical aberrations in slices of rat brain tissue were corrected with a deformable membrane mirror. Using axial resolution measurements, we demonstrate ...
Following the invention of electron optics during the 1930s, lens aberrations have limited the achievable spatial resolution to about 50 times the wavelength of the imaging electrons. This situation is similar to that faced by Leeuwenhoek in the seventeenth century, whose work to improve the quality of glass lenses led directly to his discovery of the ubiquitous "animalcules" in canal water, the ...
Following the invention of electron optics during the 1930s, lens aberrations have limited the achievable spatial resolution to about 50 times the wavelength of the imaging electrons. This situation is similar to that faced by Leeuwenhoek in the seventeenth century, whose work to improve the quality of glass lenses led directly to his discovery of the ubiquitous ``animalcules'' in canal water, the ...
The successful correction of lens aberrations in scanning transmission electron microscopy has allowed an improvement in resolution by a factor of two in just a few years. The benefits for materials research are far greater than a factor of two might imply, because enhanced resolution also brings enhanced image contrast, and therefore a vast increase in ...
The link between brown colour and vacancy structures in natural diamond and has been studied through the techniques of aberration corrected scanning transmission electron microscopy (AC-STEM) and electron energy loss spectroscopy (EELS). Bright field (BF) and high angle annular dark field (HAADF) STEM imaging modes ...
The short depth of focus of aberration-corrected scanning transmission electron microscopes (STEMs) could potentially enable 3D reconstruction of nanomaterials through acquisition of a through-focal series. However, the contrast transfer function of annular dark-field (ADF)-STEM depth sectioning has a missing-cone problem similar to that of tilt-series ...
Structural and compositional studies of nanomaterials of technological importance have been carried out using advanced electron microscopy methods, including aberration-corrected transmission electron microscopy (AC-TEM), AC-high angle annular dark field scanning TEM (AC-HAADF-STEM), AC-energy filtered TEM, electron-stimulated energy ...
Using a highly coherent focused electron probe in a fifth-order aberration-corrected transmission electron microscope, we report on resolving a crystal spacing less than 50 pm. Based on the geometrical source size and residual coherent and incoherent axial lens aberrations, an electron probe is calculated, which is theoretically capable of resolving an ...
Imaging Active Sites on Platinum Catalytic Nanoparticles Using Aberration- Corrected Electron of industrial heterogeneous catalysts are often small metallic particles, whose reactivity and selectivity on the extended surfaces of model catalysts can be identified using techniques such as scanning probe microscopy
magnification to compete with Scanning Electron Microscopy Make microscope self-contained for easeC-PEM: Aberration Corrected Photoemission Electron Microscopy J. Nettleton, R. Word, R. Koenenkamp) #12;Corrected Photoemission Electron Microscope (C-PEM) Produces images similarly to a conventional electron
The precise atomic structure of activated carbon is unknown, despite its commercial importance. Here we show that the structure of a commercial activated carbon can be imaged directly using aberration corrected transmission electron microscopy. Images are presented both of the as-produced carbon and of the carbon following heat- ...
Annular dark field scanning transmission electron microscopy imaging was recently applied to a catalyst consisting of gold nanoparticles on TiO(2) (110), showing directly that the gold atoms in small nanoparticles preferentially attach to specific sites on the TiO(2) (110) surface. Here, through simulation, a parameter exploration of the imaging conditions ...
Intrinsically ductile metals are prone to catastrophic failure when exposed to certain liquid metals, but the atomic-level mechanism for this effect is not fully understood. We characterized a model system, a nickel sample infused with bismuth atoms, by using aberration-corrected scanning transmission electron microscopy and observed a ...
The transmission electron microscope (TEM) has evolved into a highly sophisticated instrument that is ideally suited to the characterization of advanced materials. Atomic-level information is routinely accessible using both fixed-beam and scanning TEMs. This report briefly considers developments in the field of atomic-resolution electron microscopy. Recent ...
Aberration-corrected scanning transmission electron microscopy (STEM) is used to reveal individual Au atom configurations inside Si nanowires grown by Au-catalyzed vapor-liquid-solid (VLS) molecular beam epitaxy (MBE). We identify a substitutional and three distinct interstitial configurations, one of which has not been previously ...
We present an investigation of the morphology and composition of novel types of axial nanowire heterostructures where Ga(x)In(1-x)As is used as barrier material in InAs nanowires. Using aberration-corrected scanning transmission electron microscopy and energy dispersive X-ray analysis we demonstrate that it is possible to grow ...
Aberration correction of the probe forming optics of the scanning transmission electron microscope has allowed the probe-forming aperture to be increased in size, resulting in probes of the order of 1 A in diameter. The next generation of correctors promise even smaller probes. Improved spectrometer optics also ...
We report direct mapping of the grains and grain boundaries (GBs) of large-area monolayer polycrystalline graphene sheets, at large (several micrometer) and single-atom length scales. Global grain and GB mapping is performed using electron diffraction in scanning transmission electron microscopy (STEM) or using dark-field imaging in conventional TEM. ...
Chemical mapping at atomic-column resolution by energy-dispersive x-ray spectroscopy in a spherical aberration-corrected scanning transmission electron microscope (STEM) has been demonstrated for the 1.47-A dumbbell structure in InGaAs. The structural imaging and the chemical information in the two-dimensional map are directly ...
Quantum antidots (a vacancy cluster) have been proposed to account for the non-linear optical behavior of magnesium oxide (MgO) dispersed with Au nanoclusters [1,2]. In this paper, we provide convincing evidence, based on direct observation using high-angle annular dark-filed imaging in aberration corrected scanning ...
Using a fifth-order aberration-corrected scanning transmission electron microscope, which provides a factor of 100 increase in signal over an uncorrected instrument, we demonstrated two-dimensional elemental and valence-sensitive imaging at atomic resolution by means of electron energy-loss spectroscopy, with acquisition times of well ...
Three-dimensional (3D) maps of proteins within the context of whole cells are important for investigating cellular function. However, 3D reconstructions of whole cells are challenging to obtain using conventional transmission electron microscopy (TEM). We describe a methodology to determine the 3D locations of proteins labeled with gold nanoparticles on whole eukaryotic cells. ...
We discuss the dominant geometrical aberrations of a grazing incidence reflection grating and new techniques which can be used to reduce or eliminate them. Convergent beam geometries and the aberration correction possible with varied groove spacings are e...
National Technical Information Service (NTIS)
The grooved surface of an aberration-corrected holographic model grating is sensed by utilizing the sensing head of a scanning tunneling microscope. The sensing head is mechanically connected to a blazing type stylus for replicating the groove pattern of ...
ANL Electron Microscopy Center iTEAM Project EMail List Subscription Form * Your Name: First: Middle: Last: * Your Affiliation: Please do not use abbreviations * E-mail address:...
Industrial catalysts with State-of-the-art Aberration-corrected Transmission Electron Microscopy Petra Specht 66 Auditorium 2:25pm Single Crystal Dynamics by a TEM Haimei...
Monodisperse icosahedral Au nanoparticles were synthesized using one step protocol. The morphology and structural characteristics of the icosahedral Au nanoparticles with uniform size were studied in detail using ultra-high resolution scanning electron microscope (SEM) FEG Hitachi S-5500 (0.4 nm at 30 kV) with BF/DF Duo-STEM detector, high resolution ...
Compression testing of micro-pillars has recently been of great interest to the small-scale mechanics community. Previous compression tests on single crystal Mo alloy micro-pillars produced by directional solidification of eutectic alloys showed that as-grown pillars yield at strengths close to the theoretical strength while pre-strained pillars yield at considerably lower stresses. In addition, ...
The implementation of aberration correction for the scanning transmission electron microscope (STEM) enables the use of larger probe-forming apertures, improving the transverse resolution significantly and also bringing depth resolution at the nanometer scale. This opens up the possibility of three-dimensional ...
We present a detailed structural characterization of the interfaces in Fe/MgO/Fe layers grown by molecular-beam epitaxy using aberration-corrected transmission electron microscopy (TEM), scanning TEM, and electron energy-loss spectroscopy. When fabricated into magnetic tunnel junctions, these epitaxial devices exhibit large tunnel ...
We investigate the interfacial structure of PbZr0.20Ti0.80O3 (PZT)/La0.67Sr0.33MnO3 (LSMO)/SrTiO3 heterostructures by combining low-magnification transmission electron microscopy imaging and spectroscopy techniques with high-resolution spherical-aberration corrected scanning transmission ...
Gold nanoclusters dispersed in single crystal TiO?, MgO, and SrTiO? have been prepared by ion implantation at 300 K - 975 K and subsequent annealing at 1275 K for 10 hours. High resolution transmission electron microscopy and high-angle-annular-dark-field (HAADF) imaging in aberration corrected scanning ...
An automated technique for the mapping of nanocrystal phases and orientations in a transmission electron microscope (TEM) is described. It is based on the projected reciprocal lattice geometry that is extracted from electron diffraction spot patterns. The required hardware allows for a scanning-precession movement of the primary electron beam on the ...
Au nanoclusters dispersed in single crystal TiO2 and SrTiO3 have been prepared by ion implantation at 300 and 975 K and subsequent annealing at 1275 K for 10 hours. High resolution transmission electron microscopy and high-angle-annular-dark-field (HAADF) imaging in an aberration corrected scanning ...
Aberration correction in the scanning transmission electron microscope combined with electron energy loss spectroscopy allows simultaneous mapping of the structure, the chemistry and even the electronic properties of materials in one single experiment with spatial resolutions of the order of one Angstrom. Here the ...
The VG Microscopes 100 kV and 300 kV scanning transmission electron microscopes at Oak Ridge National Laboratory were equipped with Nion aberration correctors several years ago. This chapter reviews our experience with these correctors, specifically, the reduction in probe size by more than a factor of two and the associated benefits for materials ...
We demonstrate a multimodal, multifocal, differential nonlinear optical microscope, which is equipped with a pair of deformable mirrors and a Shack-Hartmann sensor for dynamic wavefront manipulation. The optical wavefronts of a home built Yb:KGW femtosecond (1028 nm) laser-beams are engineered to perform multidepth focusing in differential mode with simultaneous corrections for optical ...
In the 4 years since the previous meeting in the SALSA series, aberration correction has progressed from a promising concept to a powerful research tool. We summarize the factors that have enabled 100-120kV scanning transmission electron microscopes to achieve sub-A resolution, and to increase the current available ...
We investigate the structure of the (0001) basal twin boundary in Bi2Te3. Electron diffraction measurements show that this interface corresponds to a 180� rotation of the crystal about the [0001] axis, an alignment that reverses the stacking of the basal planes. The basal planes in the perfect Bi2Te3 structure are arranged in a repeating sequence of five-layer wide Te(1)-Bi-Te(2)-Bi-Te(1) ...
Palladium-modified activated carbon fibers (Pd-ACF) were synthesized by meltspinning, carbonization and activation of an isotropic pitch carbon precursor premixed with an organometallic Pd compound. The hydrogen uptake at 25 oC and 20 bar on Pd- ACF exceeded the expected capacity based solely on Pd hydride formation and hydrogen physisorption on the microporous carbon support. ...
Silicon nitride (Si3N4) ceramics are used in numerous applications because of their superior mechanical properties. Their intrinsically brittle nature is a critical issue, but can be overcome by introducing whisker-like microstructural features. However, the formation of such anisotropic grains is very sensitive to the type of cations used as the sintering additives. Understanding the origin of ...
Evolution of the size, shape and composition of self-assembled InAs/InP quantum wires through the Stranski-Krastanov transition has been determined by aberration-corrected Z-contrast imaging. High resolution compositional maps of the wires in the initial, intermediate and final formation stages are presented. (001) is the main facet at their very initial stage of formation, which is gradually ...
The effect of the chromatic aberration (C(c)) coefficient in a spherical aberration (C(s))- corrected electromagnetic lens on high-resolution high-angle annular dark field (HAADF) scanning transmission electron microscope (STEM) images is explored in detail. A new method for precise determination of the C(c) coefficient is demonstrated, requiring ...
High spatial resolution chemical analysis and imaging of a CrAlYN/CrN multi-layer coating was performed using sub-nanometer probe electron energy loss spectroscopy in a spherical aberration corrected scanning transmission electron microscope. Analysis indicated the CrN layers to be near stoichiometric with a ...
In this work, we structurally characterize defects, grain boundaries, and intergrowth phases observed in various Mo-V-O materials using aberration-corrected high-angle annular dark-field (HAADF) imaging within a scanning transmission electron microscope (STEM). Atomic-level imaging of these preparations clearly shows domains of the ...
Aberration-corrected scanning transmission electron microscopes (STEMs) can now produce electron probes as small as 1 {angstrom} at 60 keV. This level of performance allows individual light atoms to be imaged in various novel materials including graphene, monolayer boron nitride, and carbon nanotubes. Operation at 60 keV avoids direct ...
Complex oxides exhibit the most disparate behaviors, from ferroelectricity to high Tc superconductivity, colossal magnetoresistance to insulating properties. For these reasons, oxide thin films are of interest for electronics and the emerging field of spintronics. But epitaxial complex oxide ultrathin films and heterostructures can be significantly affected or even dominated by the presence of ...
imaging system - Part I: Transducer design and beam steering, IEEE Trans. Ultrada Fewoekcti Freq. Con& 38.D., An evaluation of transducer design and algorithm performance for two-dimensional phase aberration correctionULTRASONIC IMAGING 14, 344-353 (1992) SIMULATION OF B-SCAN IMAGES FROM TWO-DIMENSIONAL TRANSDUCER
The design and construction of a double-hexapole aberration corrector has made it possible to build the prototype of a spherical-aberration corrected transmission electron microscope dedicated to high-resolution imaging on the atomic scale. The corrected instrument, a Philips CM200 FEG ST, has an information limit of better than 0.13 ...
This study describes a prototypical, bimetallic heterogeneous catalyst: compositionally well-defined Ir-Pt nanoclusters with sizes in the range of 1-2 nm supported on ?-Al(2)O(3). Deposition of the molecular bimetallic cluster [Ir(3)Pt(3)(?-CO)(3)(CO)(3)(?-C(5)Me(5))(3)] on ?-Al(2)O(3), and its subsequent reduction with hydrogen, provides highly dispersed supported bimetallic Ir-Pt nanoparticles. ...
... Accession Number : ADA319052. Title : Demonstrating Optical Aberration Correction With a Mems Micro-Mirror Device. ...
DTIC Science & Technology
We examine the effects of aberrations induced by a refractive index mismatch on the signal level and resolution of single-photon (1-p) and two-photon (2-p), conventional and confocal scanning microscopes. In particular, we consider the aberrations introduced by an interface between oil/glass and water. Resolution is defined in terms of enclosed fluorescence, rather than ...
Owing to its solubility compared to graphene, graphene oxide (GO) has become popular in recent years as a potentially scalable precursor to graphene in devices. After the GO's oxidation and defects are chemically and thermally removed, reduced and annealed graphene oxide (raGO) remains. Using aberration-corrected transmission electron microscopy, we ...
Design of a new aberration corrected Photoemission electron microscope PEEM3 at the Advanced Light Source is outlined. PEEM3 will be installed on an elliptically polarized undulator beamline and will be used for the study of complex materials at high spatial and spectral resolution. The critical components of PEEM3 are the electron mirror aberration ...
DOE Information Bridge
Chromatic and spherical aberration-corrected atomic-resolution transmission electron microscopy combined with density-functional theory calculations is employed to elucidate the stability and dynamics of admolecules on suspended graphene. The results presented provide evidence that the interaction between the molecules and hydrogen adatoms leads to a ...
We discuss the dominant geometrical aberrations of a grazing incidence reflection grating and new techniques which can be used to reduce or eliminate them. Convergent beam geometries and the aberration correction possible with varied groove spacings are each found to improve the spectral resolution and speed of grazing incidence gratings. In combination, ...
A time-of-flight concept that dynamically corrects for chromatic aberration effects in scanning electron microscopes (SEMs) is presented. The method is predicted to reduce the microscope's chromatic aberration by an order of magnitude. The scheme should significantly improve the spatial resolution of low-voltage scanning electron microscopes (LVSEMs). The ...
Aberration correction reduces the depth of field in scanning transmission electron microscopy (STEM) and thus allows three-dimensional (3D) imaging by depth sectioning. This imaging mode offers the potential for sub-�ngstrom lateral resolution and nanometer-scale depth sensitivity. For biological samples, which ...
The resolving power of high-resolution transmission electron microscopes is characterized by the information limit, which reflects the size of the smallest object detail observable with a particular instrument. We introduce a highly accurate measurement method for the information limit, which is suitable for modern aberration-corrected electron ...
The examination of nanoparticles allows study of some processes and mechanisms that are not as easily observed for films or other types of studies where sample preparation artifacts have been cause of some uncertainties. Exposure of most clean metals to air or oxygen results in the nearly instant formation of an oxide layer. Because this initial layer normally forms in a relatively uncontrollable ...
Atomic-resolution imaging of discrete [?-SiW10O36]8- lacunary Keggin ions dispersed onto monolayer graphene oxide (GO) films by low voltage aberration corrected transmission electron microscopy is described. Under low electron beam dose, individual anions remain stationary for long enough that a variety of projections can be observed ...
Single-layer graphene can be produced by chemical vapor deposition (CVD) on copper substrates on up to meter scales [1, 2], making their polycrystallinity [3,4] almost unavoidable. By combining aberration-corrected scanning transmission electron microscopy and dark-field transmission electron microscopy, we image ...
We present a method to produce graphene and few layer graphene sheets using solution phase chemistry, which are used as ultrathin support membranes for enhanced imaging of nanomaterials using transmission electron microscopy. We demonstrate this by decorating the surface of the graphene sheets with Co-based nanocrystals (CoCl(2) and hcp Co). Low-voltage ...
We describe four new experimental techniques advanced during the last decade in the authors' laboratory. The techniques include photon scanning tunneling microscopy; aberration-corrected low-energy electron microscopy in combination with photoelectron emission microscopy, microcalorimetry, and electron-spin resonance spectroscopy. It is demonstrated how ...
Lowering the electron energy in the transmission electron microscope allows for a significant improvement in contrast of light elements and reduces knock-on damage for most materials. If low-voltage electron microscopes are defined as those with accelerating voltages below 100 kV, the introduction of aberration correctors and monochromators to the electron microscope column ...
Lowering the electron energy in the transmission electron microscope allows for a significant improvement in contrast of light elements, and reduces knock-on damage for most materials. If low-voltage electron microscopes are defined as those with accelerating voltages below 100 kV, the introduction of aberration correctors and monochromators to the electron microscope column ...
PubMed Central
Determining the three-dimensional (3D) arrangement of atoms in crystalline nanoparticles is important for nanometre-scale device engineering and also for applications involving nanoparticles, such as optoelectronics or catalysis. A nanoparticle's physical and chemical properties are controlled by its exact 3D morphology, structure and composition. Electron tomography enables the recovery of the ...
ZnO with additions of Fe(2)O(3) or In(2)O(3) shows characteristic inversion domain structures. ZnO domains are separated by two types of inversion domain boundaries (IDBs): basal b-IDBs parallel to (0001) planes, and complementary pairs of three possible variants of pyramidal p-IDBs parallel to {21�1�5} lattice planes. The structure and composition of IDBs were investigated in a sophisticated ...
There has been considerable research effort on tailoring the non-linear optical properties of dielectric materials by dispersing nanometer-sized metallic clusters in them. It has been proposed that the optical response of this type of material is related to the quantum antidots (a vacancy cluster), which is spatially located at the interface between the metal cluster and the dielectric matrix. ...
Gold nanoclusters dispersed in single crystal SrTiO(001) have been prepared by ion implantation at both 300 K and 975 K followed by annealing at 1275 K for 10 hours. Transmission electron microscopy (TEM), high-resolution TEM, high angle annular dark-filed (HAADF) imaging in an aberration corrected dedicated ...
Bimetallic nanoparticles of Au-Pd find important applications in catalysis. Their catalytic performance is directly related to the structure, alloy formation and variation of composition in the structure. A standard idea is that bimetallic nanoparticles can be either an alloy or a core shell structure. Our group has investigated the structure and composition of Pd-Au nanoparticles by using ...
Carbon-based nanofiber and microfiber cathodes exhibit very low voltages for the onset of electron emission, and thus provide exciting opportunities for applications ranging from high power microwave sources to field emission displays. CsI coatings have been experimentally shown to lower the work function for emission from the fiber tips, although little is known about the microstructure of the ...
High voltage cathode materials Li-excess layered oxide compounds Li[Ni{sub x}Li{sub 1/3-2x/3}Mn{sub 2/3-x/3}]O{sub 2} (0 < x < 1/2) are investigated in a joint study combining both computational and experimental methods. The bulk and surface structures of pristine and cycled samples of Li[Ni{sub 1/5}Li{sub 1/5}Mn{sub 3/5}]O{sub 2} are characterized by synchrotron X-Ray diffraction ...
Metastable (transition) aluminas, in particular ? -Al_2O3 and ? -Al_2O_3, are widely used as catalysts as well as supports for different transition metals. When doped with Cr, the two modifications exhibit remarkably different aging behavior: ? -Al_2O_3-supported catalysts degrade two orders of magnitude faster than those based on ? -Al_2O_3. Here we use a combination of Z-contrast ...
The recent advent of a novel design of in situ heating technology for electron microscopes has permitted unprecedented control of elevated temperature studies of catalytic materials, particularly when coupled with the sub-Angstr�m imaging performance of a modern aberration-corrected scanning transmission electron microscope (STEM). ...
Thermoelectric oxides have attracted increasing attention due to their high thermal power and temperature stability. In particular, Ca3Co4O9, a misfit layered structure consisting of single layer hole-doped CoO2 sandwiched between insulating Ca2CoO3 rocksalt layers, exhibits figure of merit (ZT) of >1 at 1000 K.^1 It was suggested that the Seebeck-coefficient can be further increased by ...
Scanning transmission electron microscopy (STEM) in combination with electron energy loss spectroscopy (EELS) has proven to be a powerful technique to study buried perovskite oxide heterointerfaces. With the recent addition of 3^rd order and now 5^th order aberration correction, which provides a factor of 100x ...
AbstractFerritin, the major iron storage protein, has dual functions; it sequesters redox activity of intracellular iron and facilitates iron turn-over. Here we present high angle annular dark field (HAADF) images from individual hepatic ferritin cores within tissue sections, these images were obtained using spherical aberration corrected ...
The question of the nature and stability of polar ordering in nanoscale ferroelectrics is examined with colloidal nanocrystals of germanium telluride (GeTe). We provide atomic-scale evidence for room-temperature polar ordering in individual nanocrystals using aberration-corrected transmission electron microscopy and demonstrate a reversible, size-dependent ...
A freestanding single layer of hexagonal boron nitride (h-BN) has been successfully fabricated by controlled energetic electron irradiation through a layer-by-layer sputtering process. We have successfully resolved atomic defects in h-BN with triangle shapes by means of an aberration corrected high-resolution transmission electron ...
Information from imaging and diffraction planes, or real and reciprocal spaces, of transmission electron microscopes (TEM) can be combined using iterative transformation algorithms to reconstruct the complex wave function, to improve image resolution and to remove residual aberrations in the case of aberration corrected TEM. Here, we ...
An ultrasmall spot size scanning laser ophthalmoscope has been developed that employs an annular aberration-corrected incident beam to increase the effective numerical aperture of the eye thereby reducing the width of the probing light spot. Parafovea and foveal cone photoreceptor visibility determined from small area retinal image ...
A dedicated two-photon microscope incorporating adaptive-optic correction of specimen-induced aberrations is presented. Wavefront alteration of the scanning laser beam was achieved by use of a micromachined deformable mirror. Post scan head implementation produces a compact module compatible with the Bio-Rad MRC-600 scan head. ...
Adaptive Optics (AO) have been increasingly combined with a variety of ophthalmic instruments over the last decade to provide cellular-level, in-vivo images of the eye. The use of MEMS deformable mirrors in these instruments has recently been demonstrated to reduce system size and cost while improving performance. However, currently available MEMS mirrors lack the required range of motion for ...
Aberration correction leads to a substantial improvement in the directly interpretable resolution of transmission electron microscopes. Correction of the aberrations has been achieved electron-optically through a hexapole-based corrector and also indirectly by computational analysis of a focal or tilt series of images. These direct and ...
Higher-order aberrations correction can improve visual performance of human eye to some extent. To evaluate how much visual benefit can be obtained with higher-order aberrations correction we developed an adaptive optics vision simulator (AOVS). Dynamic real time optimized modal compensation was used to implement ...
... transmission electron microscopy, 5 scanning electron microscopy, 6 and scanning transmission x-ray microscopy. 7 The ...
... Accession Number : AD0620937. Title : STUDY OF RANDOM SCAN TV TRANSMISSION. Descriptive Note : Final scientific rept. ...
... Title : Fiber Structure Analysis by Transmission Electron, Scanning Electron, and Field-Ion Microscopy,. Corporate Author : ...
... cycles. The studies included transmission electron microscopy (TEM), scanning electron microscopy (SEM), and scanning transmission electron ...
The history and future of transmission electron microscopy (TEM) is discussed as it refers to the eventual development of instruments and techniques applicable to the real time in situ investigation of surface processes with high resolution. To reach this objective, it was necessary to transform conventional high resolution instruments so that an ultrahigh vacuum (UHV) ...
... AND EMISSION SCANS IN POSITRON EMISSION TOMOGRAPHY. ... SOURCE ORBITS THE PATIENT SECTION DETECTOR PAIRS COLLINEAR ...
... Title : INFRARED LASER SCANNING MICROSCOPY IN TRANSMISSION: A NEW HIGH-RESOLUTION TECHNIQUE FOR THE STUDY OF ...
Voids adjacent to cubic (ZnS-type) and hexagonal (NiAs-type) Mn-rich nanocrystals are characterized using aberration-corrected transmission electron microscopy in an annealed Ga0.995Mn0.005As magnetic semiconductor specimen grown by molecular beam epitaxy. Nanobeam electron diffraction measurements suggest that the nanocrystals exhibit deviations in ...
Under specific conditions of specimen thickness and experimental settings, aberration-corrected high-resolution transmission electron microscopy images of a SiGe alloy grown on a silicon substrate display strong intensity variation from one atomic column to the other. Combining TEM image processing, semi-empirical atomic simulations of large ...
Modern transmission electron microscopes (TEM) allow utilizing the spherical aberration coefficient as an additional free parameter for optimizing resolution and contrast. By tuning the spherical aberration coefficient of the objective lens, isolated nitrogen atom columns as well as the Si-N dumbbells within the six-membered ring were imaged in beta-Si3N4 along [0001] and ...
PCM picture transmission, pseudorandom scanning, noise, bandwidth compression and digital simulation
NASA Technical Reports Server (NTRS)
Ethanol is a promising fuel for low-temperature direct fuel cell reactions due to its low toxicity, ease of storage and transportation, high energy density, and availability from biomass. However, the implementation of ethanol fuel cell technology has been hindered by the lack of low-cost, highly active anode catalysts. In this paper, we have studied Iridium (Ir) based binary catalysts as low-cost ...
Gold nanoclusters dispersed in single crystal TiO2 (110) have been formed by 2 MeV Au2+ implantation to an ion fluence of 11017 cm-2 at 300 K and 975 K followed by annealing at 1275 K for 10 hours. The morphological features, size, crystallographic orientation of the Au nanoclusters with respect to the TiO2 matrix, and the interface structure between the Au nanoclusters and TiO2 have been ...
Dispersed metal/oxide particles in or on a support matrix are the key structures determining the properties of many scientifically and technologically important materials. Two widely used examples of them which were investigated in this thesis are embedded oxide precipitates in high temperature superconductors (HTS) and supported-metal clusters in heterogeneous catalysis. The superconductive ...
A compact vacuum ultraviolet spectrometer system has been developed to provide time-resolved impurity spectra from tokamak plasmas. Two interchangeable aberration-corrected toroidal diffraction gratings with flat focal fields provide simultaneous coverage over the ranges 100 to 1100 A or 160 to 1700 A. The detector is an intensified self-scanning ...
We report a quantitative comparison of the interface structure of VN/MgO(001) using ab initio density-functional theory (DFT), aberration-corrected high-resolution transmission electron microscopy (HRTEM), and electron energy-loss spectroscopy (EELS). By HRTEM, we show an atomic resolution structure of epitaxially grown VN film on MgO with a clearly ...
In situ aberration-corrected high-resolution transmission electron microscopy is used to examine the structural transformations of carbon chains that occur in the interior region of carbon nanotubes. We find electron-beam irradiation leads to the formation of two-dimensional carbon structures that are freely mobile inside the nanotube. The inner diameter ...
We investigate the long-standing question of whether electrons accelerated at 80 kV are below the knock-on damage threshold for single-walled carbon nanotubes (SWNTs). Aberration-corrected high-resolution transmission electron microscopy is used to directly image the atomic structure of the SWNTs and provides in situ monitoring of the structural ...
We report that approximately 10% of the Au catalysts that crystallize at the tips of Ge nanowires following growth have the close-packed hexagonal crystal structure rather than the equilibrium face-centered-cubic structure. Transmission electron microscopy results using aberration-corrected imaging, and diffraction and compositional analyses, confirm the ...
High resolution local structure information is revealed when the complex exit wavefunction is restored from a series of transmission electron microscope (TEM) images. Aberration corrected image data sets allow high spatial frequency information to be restored but this is often at the expense of lower spatial frequencies. In this paper ...
One of the most challenging strategies to achieve tunable nanophotonic devices is to build robust nanohybrids with variable emission in the visible spectral range, while keeping the merits of pristine single-walled carbon nanotubes (SWNTs). This goal is realized by filling SWNTs ("pods") with a series of oligothiophene molecules ("peas"). The physical properties of these peapods are depicted by ...
High-resolution imaging of low-atomic-number chemical elements using electron microscopy is challenging and may require the use of high doses of electrons. Electron diffractive imaging, which creates real-space images using diffraction intensities and phase retrieval methods, could overcome such issues, although it is also subject to limitations. Here, we show that a combination of electron ...
The strontium titanate ?3(112)[1�10] grain boundary has been investigated using aberration-corrected high-resolution transmission electron microscopy and exit wave-function reconstruction. By quantitatively comparing the experimental exit wave phase with that expected from relaxed model structures obtained by density-functional theory, it has been ...
Using a highly coherent focused electron probe in a 5th order aberration-corrected transmission electron microscope, we report on resolving a crystal spacing less than 50 pm. Based on the geometrical source size and residual coherent and incoherent axial lens aberrations, an electron probe is calculated, which is theoretically capable of resolving an ideal ...
Two methods of spherical aberration corrections of an electrostatic gridded lens have been studied with ray tracing simulations. Both methods are based on modifying electrostatic field on the periphery of the lens. In a simplest case such modification is ...
When light time and stellar aberration corrections are both applied to a geometric position vector, the resulting position vector indicates where the target ...
NASA Website
... Section III discusses Zernike Polynomials and their common use in optics. ... III. ZERNIKE POLYNOMIALS IN OPTICAL SYSTEMS ...
The aberration of a multipole Wien filter for energy-filtered x-ray photoemission electron microscopy was analyzed and the optimized Fourier components of the electric and magnetic fields for the third-order aperture aberration corrections were obtained. It was found that the third-order aperture aberration ...
Multi-wall titanate nanotubes (MW-TNNTs) with high aspect ratio, large surface area and good uniformity were produced by alkaline hydrothermal treatment of grounded TiO2 aerogels and further by applying freeze-drying. Not only the crystal phase and diameter, but also morphology of the starting materials impact on the aspect ratio and transformation efficiency of the obtained nanotubes. Other ...
Gold nanoparticles have a high catalytic activity for CO oxidation at low temperatures providing they remain less than 5nm in diameter. Their structure and stability and the growth processes that occur during heating have been investigated using Angstrom resolution in-situ double aberration corrected transmission electron microscopy ...
... THE SCANNING TRANSMISSION ELECTRON MICROSCOPE (PART II), TECHNIQUES FOR PARTICULATE MATTER STUDIES IN SEM (PART III ...
... by Ryvola and Morris now allows rapid determination of their size, shape, and distribution in the scanning electron microscope in addition to ...
... Title : Procedure for Statistical Analysis of Single Scan Modulation Transfer Functions for Optical Transmission in the Marine Boundary Atmosphere. ...
... Present methods such as pinhole scans and knife edge scans assume spatial wave forms to fit the transmission, and those assumptions may be ...
the ability of researchers to study nanomaterials. For the majority of scanning electron microscopes, transmission electron microscopes and scanning-transmission electron...
A bright field scanning transmission electron microscope (STEM) micrograph showing a Wassonite grain in dark contrast. ...
Here, we report the structural analysis and rotational stacking faults of few-layer graphene sheets derived by the controlled pyrolysis of the solid botanical derivative camphor (C10H16O). The second-order Raman spectra of the sheets show that the graphene layers are more than one single layer, and the numbers of layers can be controlled by adjusting the amount of camphor pyrolyzed. ...
Graphene is a crystalline single layer of carbon atoms that can be viewed as an individual atomic plane extracted from graphite. Freely suspended mono-layer graphene is the thinnest possible membrane that is conceivable with currently known materials. Yet, it is remarkably stable under electron irradiation and thus opens unprecedented opportunities for electron microscopic studies. First, the ...
... Transmission electron microscope ... Electron Microscopy,, Transmission electron microscopy was selected over scanning techniques because ...
... domain patterns are examples of the magnetic structures which can be observed by defocussing the electron microscope in the transmission mode. ...
Both scanning and transmission electron micrographs are catalogued within this database. ... TEM > TRANSMISSION ELECTRON MICROSCOPY � Ancillary Description ...
... in a JEOL 3010 scanning transmission electron microscope (STEM ... and scatters electrons, but enough ... reactions, obtain electron diffraction patterns ...
[Sensor_Name: Short_Name='SCANNING ELECTRON MICROSCOPES'] ... Both scanning and transmission electron micrographs are catalogued within this database. ...
Ultrasound brain therapy is currently limited by the strong phase and amplitude aberrations induced by the heterogeneities of the skull. However the development of aberration correction techniques has made it possible to correct the beam distortion induced by the skull and to produce a sharp focus in the brain. Moreover, using the density of the skull bone ...
Bi-crystals and tri-crystals of a nominal Fe-3% Si (wt%) of well-defined orientations have been grown using a floating-zone technique with optical heating. The manufacture of these unique crystals and the preparation technique involved in harvesting thin foils from specific locations for transmission electron microscopy are described in detail. In particular, the grain ...
The attainable specimen resolution is determined by the instrumental resolution limit d(i) and by radiation damage. Solid objects such as metals are primarily damaged by atom displacement resulting from knock-on collisions of the incident electrons with the atomic nuclei. The instrumental resolution improves appreciably by means of aberration correction. ...
Silicon carbide (SiC) nanorods were prepared via reacting silicon nanopowders and multi-walled carbon nanotubes (MWCNTs) for 4h at 1100-1200�C in a molten NaCl-NaF binary salt in Ar atmosphere. The synthesised SiC nanorods were characterised by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), electron energy loss spectroscopy (EELS), and ...
The feasibility of transcranial ultrasound focusing with a non-moving phased array and without skull-specific aberration correction was investigated using computer simulations. Three cadaver skull CT image data sets were incorporated into an acoustic wave transmission model to simulate transskull ultrasound wave propagation. Using a ...
The confined interior region of carbon nanotubes has proved to be an effective "nano-test-tube" to conduct chemical reactions in a restricted volume. It also benefits from being thin and relatively transparent to electrons, enabling structural characterization using high-resolution transmission electron microscopy. This permits real-time monitoring of chemical reactions with ...
