Smart align -- A new tool for robust non-rigid registration of scanning microscope data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jones, Lewys; Yang, Hao; Pennycook, Timothy J.

Many microscopic investigations of materials may benefit from the recording of multiple successive images. This can include techniques common to several types of microscopy such as frame averaging to improve signal-to-noise ratios (SNR) or time series to study dynamic processes or more specific applications. In the scanning transmission electron microscope, this might include focal series for optical sectioning or aberration measurement, beam damage studies or camera-length series to study the effects of strain; whilst in the scanning tunnelling microscope, this might include bias voltage series to probe local electronic structure. Whatever the application, such investigations must begin with the carefulmore » alignment of these data stacks, an operation that is not always trivial. In addition, the presence of low-frequency scanning distortions can introduce intra-image shifts to the data. Here, we describe an improved automated method of performing non-rigid registration customised for the challenges unique to scanned microscope data specifically addressing the issues of low-SNR data, images containing a large proportion of crystalline material and/or local features of interest such as dislocations or edges. Careful attention has been paid to artefact testing of the non-rigid registration method used, and the importance of this registration for the quantitative interpretation of feature intensities and positions is evaluated.« less

Nano-fEM: protein localization using photo-activated localization microscopy and electron microscopy.

PubMed

Watanabe, Shigeki; Richards, Jackson; Hollopeter, Gunther; Hobson, Robert J; Davis, Wayne M; Jorgensen, Erik M

2012-12-03

Mapping the distribution of proteins is essential for understanding the function of proteins in a cell. Fluorescence microscopy is extensively used for protein localization, but subcellular context is often absent in fluorescence images. Immuno-electron microscopy, on the other hand, can localize proteins, but the technique is limited by a lack of compatible antibodies, poor preservation of morphology and because most antigens are not exposed to the specimen surface. Correlative approaches can acquire the fluorescence image from a whole cell first, either from immuno-fluorescence or genetically tagged proteins. The sample is then fixed and embedded for electron microscopy, and the images are correlated (1-3). However, the low-resolution fluorescence image and the lack of fiducial markers preclude the precise localization of proteins. Alternatively, fluorescence imaging can be done after preserving the specimen in plastic. In this approach, the block is sectioned, and fluorescence images and electron micrographs of the same section are correlated (4-7). However, the diffraction limit of light in the correlated image obscures the locations of individual molecules, and the fluorescence often extends beyond the boundary of the cell. Nano-resolution fluorescence electron microscopy (nano-fEM) is designed to localize proteins at nano-scale by imaging the same sections using photo-activated localization microscopy (PALM) and electron microscopy. PALM overcomes the diffraction limit by imaging individual fluorescent proteins and subsequently mapping the centroid of each fluorescent spot (8-10). We outline the nano-fEM technique in five steps. First, the sample is fixed and embedded using conditions that preserve the fluorescence of tagged proteins. Second, the resin blocks are sectioned into ultrathin segments (70-80 nm) that are mounted on a cover glass. Third, fluorescence is imaged in these sections using the Zeiss PALM microscope. Fourth, electron dense structures are imaged in these same sections using a scanning electron microscope. Fifth, the fluorescence and electron micrographs are aligned using gold particles as fiducial markers. In summary, the subcellular localization of fluorescently tagged proteins can be determined at nanometer resolution in approximately one week.

Electron-beam-induced potentials in semiconductors: calculation and measurement with an SEM/SPM hybrid system

NASA Astrophysics Data System (ADS)

Thomas, Ch; Joachimsthaler, I.; Heiderhoff, R.; Balk, L. J.

2004-10-01

In this work electron-beam-induced potentials are analysed theoretically and experimentally for semiconductors. A theoretical model is developed to describe the surface potential distribution produced by an electron beam. The distribution of generated carriers is calculated using semiconductor equations. This distribution causes a local change in surface potential, which is derived with the help of quasi-Fermi energies. The potential distribution is simulated using the model developed and measured with a scanning probe microscope (SPM) built inside a scanning electron microscope (SEM), for different samples, for different beam excitations and for different cantilever voltages of SPM. In the end, some fields of application are shown where material properties can be determined using an SEM/SPM hybrid system.

Using an Electron Scanning Microscope to Assess the Penetrating Abilities of an Experimental Preparation with Features of a Dental Infiltrant: Preliminary Study.

PubMed

Skucha-Nowak, Małgorzata; Mertas, Anna; Tanasiewicz, Marta

2016-01-01

The resin infiltration technique is one of the micro-invasive methods whose aim is the penetration of demineralized enamel with a low viscosity resin. This technique allows the dentist to avoid the application of mechanical means of treatment. The objective of this preliminary study was to attempt to determine the possibilities of using an electron microscope to assess the penetrating abilities of an experimental preparation with features of a dental infiltrant and to compare the depth of infiltration of the designed experimental preparation with an infiltrant available on the market. A bioactive methacrylate monomer based on PMMAn with built-in metronidazole was synthesized. The commercially available Icon solution (with contrast agent YbF3) and the experimental solution were applied to the relevant parts of teeth. The dissected sections along the long tooth axis and polished surfaces were then examined with use of an electron scanning microscope. The backscattered electron technique gives much better results than the secondary electron method as it makes it possible to localize even very small YbF3 particles. The authors concluded that the backscattered electron technique gives much better results than the secondary electron method as it makes it possible to localize even very small particles of the contrast agent. In order to prevent blockage of decalcified enamel tissue by ytterbium trifluoride (YbF3) grains, a nanoparticle form of that compound should be used (that is, particles with sizes in the range of 10-9 m).

Frenkel versus charge-transfer exciton dispersion in molecular crystals

NASA Astrophysics Data System (ADS)

Cudazzo, Pierluigi; Gatti, Matteo; Rubio, Angel; Sottile, Francesco

2013-11-01

By solving the many-body Bethe-Salpeter equation at finite momentum transfer, we characterize the exciton dispersion in two prototypical molecular crystals, picene and pentacene, in which localized Frenkel excitons compete with delocalized charge-transfer excitons. We explain the exciton dispersion on the basis of the interplay between electron and hole hopping and electron-hole exchange interaction, unraveling a simple microscopic description to distinguish Frenkel and charge-transfer excitons. This analysis is general and can be applied to other systems in which the electron wave functions are strongly localized, as in strongly correlated insulators.

An in-plane magnetic chiral dichroism approach for measurement of intrinsic magnetic signals using transmitted electrons

PubMed Central

Song, Dongsheng; Tavabi, Amir H.; Li, Zi-An; Kovács, András; Rusz, Ján; Huang, Wenting; Richter, Gunther; Dunin-Borkowski, Rafal E.; Zhu, Jing

2017-01-01

Electron energy-loss magnetic chiral dichroism is a powerful technique that allows the local magnetic properties of materials to be measured quantitatively with close-to-atomic spatial resolution and element specificity in the transmission electron microscope. Until now, the technique has been restricted to measurements of the magnetic circular dichroism signal in the electron beam direction. However, the intrinsic magnetization directions of thin samples are often oriented in the specimen plane, especially when they are examined in magnetic-field-free conditions in the transmission electron microscope. Here, we introduce an approach that allows in-plane magnetic signals to be measured using electron magnetic chiral dichroism by selecting a specific diffraction geometry. We compare experimental results recorded from a cobalt nanoplate with simulations to demonstrate that an electron magnetic chiral dichroism signal originating from in-plane magnetization can be detected successfully. PMID:28504267

Fabrication of large area plasmonic nanoparticle grating structure on silver halide based transmission electron microscope film and its application as a surface enhanced Raman spectroscopy substrate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sudheer,, E-mail: sudheer@rrcat.gov.in; Tiwari, P.; Singh, M. N.

The plasmonic responses of silver nanoparticle grating structures of different periods made on silver halide based electron microscope film are investigated. Raster scan of the conventional scanning electron microscope (SEM) is used to carry out electron beam lithography for fabricating the plasmonic nanoparticle grating (PNG) structures. Morphological characterization of the PNG structures, carried out by the SEM and the atomic force microscope, indicates that the depth of the groove decreases with a decrease in the grating period. Elemental characterization performed by the energy dispersive spectroscopy and the x-ray diffraction shows the presence of nanoparticles of silver in the PNG grating.more » The optical characterization of the gratings shows that the localized surface plasmon resonance peak shifts from 366 to 378 nm and broadens with a decrease in grating period from 10 to 2.5 μm. The surface enhanced Raman spectroscopy of the Rhodamine-6G dye coated PNG structure shows the maximum enhancement by two orders of magnitude in comparison to the randomly distributed silver nanoparticles having similar size and shape as the PNG structure.« less

Application of automatic image analysis for morphometric studies of peroxisomes stained cytochemically for catalase. II. Light-microscopic application.

PubMed

Beier, K; Fahimi, H D

1987-01-01

The feasibility of the application of a television-based image analyzer, the Texture Analysis System (TAS, Leitz Wetzlar, FRG) in conjunction with a light microscope for morphometric studies of hepatic peroxisomes has been investigated. Rat liver peroxisomes were stained with the alkaline-DAB method for localization of catalase and semithin (0.25 and 1 micron) sections of plastic-embedded material were examined under an oil immersion objective. The TAS detected the peroxisomal profiles selectively and determined their morphometric parameters automatically. The same parameters were obtained also by morphometric analysis of electron micrographs from the same material. The volume density of peroxisomes determined by TAS in semithin sections of normal liver, after correction for section thickness, is quite close to the corresponding value obtained by morphometry of electron micrographs. The difference is approximately 20%. In animals treated with the hypolipidemic drug bezafibrate, which causes proliferation of peroxisomes, TAS detected readily the increase in volume density of peroxisomes in semithin sections. In comparison with electron microscopy, however, the light-microscopic approach seems to underestimate the proliferation. The lower resolution of the light microscope and overlapping of neighbouring particles in relatively thick sections used for light-microscopic analysis may account for the differences. The present study has demonstrated the usefulness of automatic image analysis in conjunction with selective cytochemical staining of peroxisomes for morphometry of this organelle in rat liver. The light-microscopic approach is not only faster but is also extremely economical by obviating the use of an electron microscope.

The qualitative f-ratio method applied to electron channelling-induced x-ray imaging with an annular silicon drift detector in a scanning electron microscope in the transmission mode.

PubMed

Brodusch, Nicolas; Gauvin, Raynald

2017-09-01

Electron channelling is known to affect the x-ray production when an accelerated electron beam is applied to a crystalline material and is highly dependent on the local crystal orientation. This effect, unless very long counting time are used, is barely noticeable on x-ray energy spectra recorded with conventional silicon drift detectors (SDD) located at a small elevation angle. However, the very high count rates provided by the new commercially available annular SDDs permit now to observe this effect routinely and may, in some circumstances, hide the true elemental x-ray variations due to the local true specimen composition. To circumvent this issue, the recently developed f-ratio method was applied to display qualitatively the true net intensity x-ray variations in a thin specimen of a Ti-6Al-4V alloy in a scanning electron microscope in transmission mode. The diffraction contrast observed in the x-ray images was successfully cancelled through the use of f-ratios and the true composition variations at the grain boundaries could be observed in relation to the dislocation alignment prior to the β-phase nucleation. The qualitative effectiveness in removing channelling effects demonstrated in this work makes the f-ratio, in its quantitative form, a possible alternative to the ZAF method in channelling conditions. © 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.

Microscopic dynamics research on the "mature" process of dye-sensitized solar cells after injection of highly concentrated electrolyte.

PubMed

Liang, Zhongguan; Liu, Weiqing; Chen, Jun; Hu, Linhua; Dai, Songyuan

2015-01-21

After injection of electrolyte, the internal three-dimensional solid-liquid penetration system of dye-sensitized solar cells (DSCs) can take a period of time to reach "mature" state. This paper studies the changes of microscopic processes of DSCs including TiO2 energy-level movement, localized state distribution, charge accumulation, electron transport, and recombination dynamics, from the beginning of electrolyte injection to the time of reached mature state. The results show that the microscopic dynamics process of DSCs exhibited a time-dependent behavior and achieved maturity ∼12 h after injecting the electrolyte into DSCs. Within 0-12 h, several results were observed: (1) the conduction band edge of TiO2 moved slightly toward negative potential direction; (2) the localized states in the band gap of TiO2 was reduced according to the same distribution law; (3) the transport resistance in TiO2 film increased, and electron transport time was prolonged as the time of maturity went on, which indicated that the electron transport process is impeded gradually; (4) the recombination resistance at the TiO2/electrolyte (EL) interface increases, and electron lifetime gradually extends, therefore, the recombination process is continuously suppressed. Furthermore, results suggest that the parameters of EL/Pt-transparent conductive oxide (TCO) interface including the interfacial capacitance, electron-transfer resistance, and transfer time constant would change with time of maturity, indicating that the EL/Pt-TCO interface is a potential factor affecting the mature process of DSCs.

Plasmonic characterization of photo-induced silver nanoparticles extracted from silver halide based TEM film

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sudheer,, E-mail: sudheer@rrcat.gov.in; Tiwari, P.; Rai, V. N.

The plasmonic responses of silver nanoparticles extracted from silver halide based electron microscope film are investigated. Photo-reduction process is carried out to convert the silver halide grains into the metallic silver. The centrifuge technique is used for separating the silver nanoparticles from the residual solution. Morphological study performed by field emission scanning electron microscope (FESEM) shows that all the nanoparticles have an average diameter of ~120 nm with a high degree of mono dispersion in size. The localized surface plasmon resonance (LSPR) absorption peak at ~537 nm confirms the presence of large size silver nanoparticles.

Transmission electron microscopy: direct observation of crystal structure in refractory ceramics.

PubMed

Shaw, T M; Thomas, G

1978-11-10

Using high-resolution multibeam interference techniques in the transmission electron microscope, images have been obtained that make possible a real-space structure analysis of a beryllium-silicon-nitrogen compound. The results illustrate the usefulness of lattice imaging in the analysis of local crystal structure in these technologically promising ceramic materials.

A theory of local and global processes which affect solar wind electrons. 2: Experimental support

NASA Technical Reports Server (NTRS)

Scudder, J. D.; Olbert, S.

1979-01-01

The microscopic characteristics of the Coulomb cross section show that there are three natural subpopulations for plasma electrons: the subthermals with local kinetic energy E kT sub c; the transthermals with kT sub c E 7 kT sub c and the extrathermals E 7 kT sub c. Data from three experimental groups on three different spacecraft in the interplanetary medium over a radial range are presented to support the five interrelations projected between solar wind electron properties and changes in the interplanetary medium: (1) subthermals respond primarily to local changes (compression and rarefactions) in stream dynamics; (2) the extrathermal fraction of the ambient electron density should be anti-correlated with the asymptotic bulk speed; (3) the extrathermal "temperature" should be anti-correlated with the local wind speed at 1 AU; (4) the heat flux carried by electrons should be anti-correlated with the local bulk speed; and (5) the extrathermal differential 'temperature' should be nearly independent of radius within 1 AU.

Scanning electron microscope fractography in failure analysis of steels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wouters, R.; Froyen, L.

1996-04-01

For many failure cases, macroscopic examination of the fracture surface permits discrimination of fatigue fractures from overload fractures. For clarifying fatigue fractures, the practical significance of microfractography is limited to an investigation of the crack initiation areas. Scanning electron microscopy is successfully used in tracing local material abnormalities that act as fatigue crack initiators. The task for the scanning electron microscope, however, is much more substantial in failure analysis of overload fractures, especially for steels. By revealing specific fractographic characteristics, complemented by information about the material and the loading conditions, scanning electron microscopy provides a strong indication of the probablemore » cause of failure. A complete dimple fracture is indicative of acceptable bulk material properties; overloading, by subdimensioning or excessive external loading, has to be verified. The presence of cleavage fracture makes the material properties questionable if external conditions causing embrittlement are absent. Intergranular brittle fracture requires verification of grain-boundary weakening conditions--a sensitized structure, whether or not combined with a local stress state or a specific environment. The role of scanning electron microscopy in failure analysis is illustrated by case histories of the aforementioned fracture types.« less

Spectral function of few electrons in quantum wires and carbon nanotubes as a signature of Wigner localization

NASA Astrophysics Data System (ADS)

Secchi, Andrea; Rontani, Massimo

2012-03-01

We demonstrate that the profile of the space-resolved spectral function at finite temperature provides a signature of Wigner localization for electrons in quantum wires and semiconducting carbon nanotubes. Our numerical evidence is based on the exact diagonalization of the microscopic Hamiltonian of few particles interacting in gate-defined quantum dots. The minimal temperature required to suppress residual exchange effects in the spectral function image of (nanotubes) quantum wires lies in the (sub)kelvin range.

Tip-induced reduction of the resonant tunneling current on semiconductor surfaces.

PubMed

Jelínek, Pavel; Svec, Martin; Pou, Pablo; Perez, Ruben; Cháb, Vladimír

2008-10-24

We report scanning tunneling microscope measurements showing a substantial decrease of the current, almost to zero, on the Si(111)-(7x7) reconstruction in the near-to-contact region under low bias conditions. First principles simulations for the tip-sample interaction and transport calculations show that this effect is driven by the substantial local modification of the atomic and electronic structure of the surface. The chemical reactivity of the adatom dangling bond states that dominate the electronic density of states close to the Fermi level and their spatial localization result in a strong modification of the electronic current.

SEM probe of IC radiation sensitivity

NASA Technical Reports Server (NTRS)

Gauthier, M. K.; Stanley, A. G.

1979-01-01

Scanning Electron Microscope (SEM) used to irradiate single integrated circuit (IC) subcomponent to test for radiation sensitivity can localize area of IC less than .03 by .03 mm for determination of exact location of radiation sensitive section.

Direct-write liquid phase transformations with a scanning transmission electron microscope

DOE Office of Scientific and Technical Information (OSTI.GOV)

Unocic, Raymond R.; Lupini, Andrew R.; Borisevich, Albina Y.

The highly energetic electron beam from a scanning transmission electron microscope (STEM) can induce local changes in the state of matter, ranging from local knock-out and atomic movement, to amorphization/crystallization, and chemical/electrochemical reactions occuring at localized liquid-solid and gas-solid interfaces. To date, fundamental studies of e-beam induced phenomena and practical applications have been limited by conventional e-beam rastering modes that allow only for uniform e-beam exposures. Here we develop an automated liquid phase nanolithography method that is capable of directly writing nanometer scaled features within silicon nitride encapsulated liquid cells. An external beam control system, connected to the scan coilsmore » of an aberration-corrected STEM, is used to precisely control the position, dwell time, and scan velocity of a sub-nanometer STEM probe. Site-specific locations in a sealed liquid cell containing an aqueous solution of H 2PdCl 4 are irradiated to controllably deposit palladium onto silicon nitride membranes. We determine the threshold electron dose required for the radiolytic deposition of metallic palladium, explore the influence of electron dose on the feature size and morphology of nanolithographically patterned nanostructures, and propose a feedback-controlled monitoring method for active control of the nanofabricated structures through STEM detector signal monitoring. As a result, this approach enables both fundamental studies of electron beam induced interactions with matter, as well as opens a pathway to fabricate nanostructures with tailored architectures and chemistries via shape-controlled nanolithographic patterning from liquid phase precursors.« less

Direct-write liquid phase transformations with a scanning transmission electron microscope

DOE PAGES

Unocic, Raymond R.; Lupini, Andrew R.; Borisevich, Albina Y.; ...

2016-08-03

The highly energetic electron beam from a scanning transmission electron microscope (STEM) can induce local changes in the state of matter, ranging from local knock-out and atomic movement, to amorphization/crystallization, and chemical/electrochemical reactions occuring at localized liquid-solid and gas-solid interfaces. To date, fundamental studies of e-beam induced phenomena and practical applications have been limited by conventional e-beam rastering modes that allow only for uniform e-beam exposures. Here we develop an automated liquid phase nanolithography method that is capable of directly writing nanometer scaled features within silicon nitride encapsulated liquid cells. An external beam control system, connected to the scan coilsmore » of an aberration-corrected STEM, is used to precisely control the position, dwell time, and scan velocity of a sub-nanometer STEM probe. Site-specific locations in a sealed liquid cell containing an aqueous solution of H 2PdCl 4 are irradiated to controllably deposit palladium onto silicon nitride membranes. We determine the threshold electron dose required for the radiolytic deposition of metallic palladium, explore the influence of electron dose on the feature size and morphology of nanolithographically patterned nanostructures, and propose a feedback-controlled monitoring method for active control of the nanofabricated structures through STEM detector signal monitoring. As a result, this approach enables both fundamental studies of electron beam induced interactions with matter, as well as opens a pathway to fabricate nanostructures with tailored architectures and chemistries via shape-controlled nanolithographic patterning from liquid phase precursors.« less

[Electron microscopic study of the An-750 strain of Powassan virus isolated in the Soviet Union].

PubMed

Sobolev, S G; Shestopalova, N M; Linev, M B; Rubin, S G

1978-01-01

Electron microscopic examinations of brains of white mice inoculated with the An 750 strain isolated for the first time from adult mosquitoes and with the prototype LB strain of Powassan virus were carried out. The method of combination of light and electron microscopy used in the study permitted to compare ultrastructural changes in one cell with the results of light microscopy. Sizes of virions and their localizations in the brain cells were determined. Virus particles were found in large and small neurons as well as in glial elements. Subcellular changes in neurons associated with virus multiplication are described. The causes of differences in sizes of virions measured in ultrathin sections are discussed.

Simulating electron wave dynamics in graphene superlattices exploiting parallel processing advantages

NASA Astrophysics Data System (ADS)

Rodrigues, Manuel J.; Fernandes, David E.; Silveirinha, Mário G.; Falcão, Gabriel

2018-01-01

This work introduces a parallel computing framework to characterize the propagation of electron waves in graphene-based nanostructures. The electron wave dynamics is modeled using both "microscopic" and effective medium formalisms and the numerical solution of the two-dimensional massless Dirac equation is determined using a Finite-Difference Time-Domain scheme. The propagation of electron waves in graphene superlattices with localized scattering centers is studied, and the role of the symmetry of the microscopic potential in the electron velocity is discussed. The computational methodologies target the parallel capabilities of heterogeneous multi-core CPU and multi-GPU environments and are built with the OpenCL parallel programming framework which provides a portable, vendor agnostic and high throughput-performance solution. The proposed heterogeneous multi-GPU implementation achieves speedup ratios up to 75x when compared to multi-thread and multi-core CPU execution, reducing simulation times from several hours to a couple of minutes.

Automated in-chamber specimen coating for serial block-face electron microscopy.

PubMed

Titze, B; Denk, W

2013-05-01

When imaging insulating specimens in a scanning electron microscope, negative charge accumulates locally ('sample charging'). The resulting electric fields distort signal amplitude, focus and image geometry, which can be avoided by coating the specimen with a conductive film prior to introducing it into the microscope chamber. This, however, is incompatible with serial block-face electron microscopy (SBEM), where imaging and surface removal cycles (by diamond knife or focused ion beam) alternate, with the sample remaining in place. Here we show that coating the sample after each cutting cycle with a 1-2 nm metallic film, using an electron beam evaporator that is integrated into the microscope chamber, eliminates charging effects for both backscattered (BSE) and secondary electron (SE) imaging. The reduction in signal-to-noise ratio (SNR) caused by the film is smaller than that caused by the widely used low-vacuum method. Sample surfaces as large as 12 mm across were coated and imaged without charging effects at beam currents as high as 25 nA. The coatings also enabled the use of beam deceleration for non-conducting samples, leading to substantial SNR gains for BSE contrast. We modified and automated the evaporator to enable the acquisition of SBEM stacks, and demonstrated the acquisition of stacks of over 1000 successive cut/coat/image cycles and of stacks using beam deceleration or SE contrast. © 2013 The Authors Journal of Microscopy © 2013 Royal Microscopical Society.

Microscopic Electron Dynamics in Metal Nanoparticles for Photovoltaic Systems.

PubMed

Kluczyk, Katarzyna; Jacak, Lucjan; Jacak, Witold; David, Christin

2018-06-25

Nanoparticles—regularly patterned or randomly dispersed—are a key ingredient for emerging technologies in photonics. Of particular interest are scattering and field enhancement effects of metal nanoparticles for energy harvesting and converting systems. An often neglected aspect in the modeling of nanoparticles are light interaction effects at the ultimate nanoscale beyond classical electrodynamics. Those arise from microscopic electron dynamics in confined systems, the accelerated motion in the plasmon oscillation and the quantum nature of the free electron gas in metals, such as Coulomb repulsion and electron diffusion. We give a detailed account on free electron phenomena in metal nanoparticles and discuss analytic expressions stemming from microscopic (Random Phase Approximation—RPA) and semi-classical (hydrodynamic) theories. These can be incorporated into standard computational schemes to produce more reliable results on the optical properties of metal nanoparticles. We combine these solutions into a single framework and study systematically their joint impact on isolated Au, Ag, and Al nanoparticles as well as dimer structures. The spectral position of the plasmon resonance and its broadening as well as local field enhancement show an intriguing dependence on the particle size due to the relevance of additional damping channels.

Manipulation of subsurface carbon nanoparticles in Bi 2 Sr 2 CaCu 2 O 8 + δ using a scanning tunneling microscope

DOE PAGES

Stollenwerk, A. J.; Hurley, N.; Beck, B.; ...

2015-03-19

In this study, we present evidence that subsurface carbon nanoparticles in Bi₂Sr₂CaCu₂O 8+δ can be manipulated with nanometer precision using a scanning tunneling microscope. High resolution images indicate that most of the carbon particles remain subsurface after transport observable as a local increase in height as the particle pushes up on the surface. Tunneling spectra in the vicinity of these protrusions exhibit semiconducting characteristics with a band gap of approximately 1.8 eV, indicating that the incorporation of carbon locally alters the electronic properties near the surface.

Image simulation for electron energy loss spectroscopy

DOE PAGES

Oxley, Mark P.; Pennycook, Stephen J.

2007-10-22

In this paper, 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 Å in diameter. The next generation of correctors promise even smaller probes. Improved spectrometer optics also offers the possibility of larger electron energy loss spectrometry detectors. The localization of images based on core-loss electron energy loss spectroscopy is examined as function of both probe-forming aperture and detector size. The effective ionization is nonlocal in nature, and two common local approximations are compared to full nonlocal calculations.more » Finally, the affect of the channelling of the electron probe within the sample is also discussed.« less

A comparison of caveolae and caveolin-1 to folate receptor α in retina and retinal pigment epithelium

PubMed Central

Bridges, Christy C.; El-Sherbeny, Amira; Roon, Penny; Ola, M. Shamsul; Kekuda, Ramesh; Ganapathy, Vadivel; Cameron, Richard S.; Cameron, Patricia L.

2015-01-01

Summary Caveolae are flask-shaped membrane invaginations present in most mammalian cells. They are distinguished by the presence of a striated coat composed of the protein, caveolin. Caveolae have been implicated in numerous cellular processes, including potocytosis in which caveolae are hypothesized to co-localize with folate receptor α and participate in folate uptake. Our laboratory has recently localized folate receptor α to the basolateral surface of the retinal pigment epithelium (RPE). It is present also in many other cells of the retina. In the present study, we asked whether caveolae were present in the RPE, and if so, whether their pattern of distribution was similar to folate receptor α. We also examined the distribution pattern of caveolin-1, which can be a marker of caveolae. Extensive electron microscopical analysis revealed caveolae associated with endothelial cells. However, none were detected in intact or cultured RPE. Laser scanning confocal microscopical analysis of intact RPE localized caveolin-1 to the apical and basal surfaces, a distribution unlike folate receptor α. Western analysis confirmed the presence of caveolin-1 in cultured RPE cells and laser scanning confocal microscopy localized the protein to the basal plasma membrane of the RPE, a distribution like that of folate receptor α. This distribution was confirmed by electron microscopic immunolocalization. The lack of caveolae in the RPE suggests that these structures may not be essential for folate internalization in the RPE. PMID:11508338

High spatial resolution detection of low-energy electrons using an event-counting method, application to point projection microscopy

NASA Astrophysics Data System (ADS)

Salançon, Evelyne; Degiovanni, Alain; Lapena, Laurent; Morin, Roger

2018-04-01

An event-counting method using a two-microchannel plate stack in a low-energy electron point projection microscope is implemented. 15 μm detector spatial resolution, i.e., the distance between first-neighbor microchannels, is demonstrated. This leads to a 7 times better microscope resolution. Compared to previous work with neutrons [Tremsin et al., Nucl. Instrum. Methods Phys. Res., Sect. A 592, 374 (2008)], the large number of detection events achieved with electrons shows that the local response of the detector is mainly governed by the angle between the hexagonal structures of the two microchannel plates. Using this method in point projection microscopy offers the prospect of working with a greater source-object distance (350 nm instead of 50 nm), advancing toward atomic resolution.

Local electric field direct writing – Electron-beam lithography and mechanism

DOE PAGES

Jiang, Nan; Su, Dong; Spence, John C. H.

2017-08-24

Local electric field induced by a focused electron probe in silicate glass thin films is evaluated in this paper by the migration of cations. Extremely strong local electric fields can be obtained by the focused electron probe from a scanning transmission electron microscope. As a result, collective atomic displacements occur. This newly revised mechanism provides an efficient tool to write patterned nanostructures directly, and thus overcome the low efficiency of the conventional electron-beam lithography. Applying this technique to silicate glass thin films, as an example, a grid of rods of nanometer dimension can be efficiently produced by rapidly scanning amore » focused electron probe. This nanopatterning is achieved through swift phase separation in the sample, without any post-development processes. The controlled phase separation is induced by massive displacements of cations (glass modifiers) within the glass-former network, driven by the strong local electric fields. The electric field is induced by accumulated charge within the electron probed region, which is generated by the excitation of atomic electrons by the incident electron. Throughput is much improved compared to other scanning probe techniques. Finally, the half-pitch spatial resolution of nanostructure in this particular specimen is 2.5 nm.« less

Local electric field direct writing – Electron-beam lithography and mechanism

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiang, Nan; Su, Dong; Spence, John C. H.

Local electric field induced by a focused electron probe in silicate glass thin films is evaluated in this paper by the migration of cations. Extremely strong local electric fields can be obtained by the focused electron probe from a scanning transmission electron microscope. As a result, collective atomic displacements occur. This newly revised mechanism provides an efficient tool to write patterned nanostructures directly, and thus overcome the low efficiency of the conventional electron-beam lithography. Applying this technique to silicate glass thin films, as an example, a grid of rods of nanometer dimension can be efficiently produced by rapidly scanning amore » focused electron probe. This nanopatterning is achieved through swift phase separation in the sample, without any post-development processes. The controlled phase separation is induced by massive displacements of cations (glass modifiers) within the glass-former network, driven by the strong local electric fields. The electric field is induced by accumulated charge within the electron probed region, which is generated by the excitation of atomic electrons by the incident electron. Throughput is much improved compared to other scanning probe techniques. Finally, the half-pitch spatial resolution of nanostructure in this particular specimen is 2.5 nm.« less

Effective absorption correction for energy dispersive X-ray mapping in a scanning transmission electron microscope: analysing the local indium distribution in rough samples of InGaN alloy layers.

PubMed

Wang, X; Chauvat, M-P; Ruterana, P; Walther, T

2017-12-01

We have applied our previous method of self-consistent k*-factors for absorption correction in energy-dispersive X-ray spectroscopy to quantify the indium content in X-ray maps of thick compound InGaN layers. The method allows us to quantify the indium concentration without measuring the sample thickness, density or beam current, and works even if there is a drastic local thickness change due to sample roughness or preferential thinning. The method is shown to select, point-by-point in a two-dimensional spectrum image or map, the k*-factor from the local Ga K/L intensity ratio that is most appropriate for the corresponding sample geometry, demonstrating it is not the sample thickness measured along the electron beam direction but the optical path length the X-rays have to travel through the sample that is relevant for the absorption correction. © 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.

New trend in electron holography

NASA Astrophysics Data System (ADS)

Tanigaki, Toshiaki; Harada, Ken; Murakami, Yasukazu; Niitsu, Kodai; Akashi, Tetsuya; Takahashi, Yoshio; Sugawara, Akira; Shindo, Daisuke

2016-06-01

Electron holography using a coherent electron wave is a promising technique for high-resolution visualization of electromagnetic fields in and around objects. The capability of electron holography has been enhanced by the development of new technologies and has thus become an even more powerful tool for exploring scientific frontiers. This review introduces these technologies including split-illumination electron holography and vector-field electron tomography. Split-illumination electron holography, which uses separated coherent waves, overcomes the limits imposed by the lateral coherence requirement for electron waves in electron holography. Areas that are difficult to observe using conventional electron holography are now observable. Exemplified applications include observing a singular magnetic domain wall in electrical steel sheets, local magnetizations at anti-phase boundaries, and electrostatic potentials in metal-oxide-semiconductor field-effect transistors. Vector-field electron tomography can be used to visualize magnetic vectors in three dimensions. Two components of the vectors are reconstructed using dual-axis tomography, and the remaining one is calculated using div B   =  0. A high-voltage electron microscope can be used to achieve precise magnetic reconstruction. For example, magnetic vortices have been visualized using a 1 MV holography electron microscope.

Scanned gate microscopy of inter-edge channel scattering in the quantum Hall regime

NASA Astrophysics Data System (ADS)

Woodside, Michael T.; Vale, Chris; McEuen, Paul L.; Kadow, C.; Maranowski, K. D.; Gossard, A. C.

2000-03-01

Novel scanned probe techniques have recently been used to study in detail the microscopic properties of 2D electron gases in the quantum Hall regime [1]. We report local measurements of the scattering between edge states in a quantum Hall conductor with non-equilibrium edge state populations. Using an atomic force microscope (AFM) tip as a local gate to perturb the edge states, we find that the scattering is dominated by individual, microscopic scattering sites, which we directly image and characterise. The dependence of the scattering on the AFM tip voltage reveals that it involves tunneling both through quasi-bound impurity states and through disorder-induced weak links between the edge states. [1] S. H. Tessmer et al., Nature 392, 51 (1998); K. L. McCormick et al., Phys. Rev. B 59, 4654 (1999); A. Yacoby et al., Solid State Comm. 111, 1 (1999).

Microscopic theoretical study of frequency dependent dielectric constant of heavy fermion systems

NASA Astrophysics Data System (ADS)

Shadangi, Keshab Chandra; Rout, G. C.

2017-05-01

The dielectric polarization and the dielectric constant plays a vital role in the deciding the properties of the Heavy Fermion Systems. In the present communication we consider the periodic Anderson's Model which consists of conduction electron kinetic energy, localized f-electron kinetic energy and the hybridization between the conduction and localized electrons, besides the Coulomb correlation energy. We calculate dielectric polarization which involves two particle Green's functions which are calculated by using Zubarev's Green's function technique. Using the equations of motion of the fermion electron operators. Finally, the temperature and frequency dependent dielectric constant is calculated from the dielectric polarization function. The charge susceptibility and dielectric constant are computed numerically for different physical parameters like the position (Ef) of the f-electron level with respect to fermi level, the strength of the hybridization (V) between the conduction and localized f-electrons, Coulomb correlation potential temperature and optical phonon wave vector (q). The results will be discussed in a reference to the experimental observations of the dielectric constants.

Universality classes of order parameters composed of many-body bound states

DOE PAGES

Tsvelik, A. M.

2016-11-28

This theoretical paper discusses microscopic models giving rise to special types of order in which conduction electrons are bound together with localized spins to create composite order parameters. It is shown that composite order is related to the formation of a spin liquid with gapped excitations carrying quantum numbers which are a fraction of those of electron. These spin liquids are special in the sense that their formation necessarily involves spin degrees of freedom of both the conduction and the localized electrons and can be characterized by nonlocal order parameters. A detailed description of such spin liquid states is presentedmore » with a special care given to a demonstration of their robustness against local perturbations preserving the Lie group symmetry and the translational invariance.« less

In situ TEM Raman spectroscopy and laser-based materials modification.

PubMed

Allen, F I; Kim, E; Andresen, N C; Grigoropoulos, C P; Minor, A M

2017-07-01

We present a modular assembly that enables both in situ Raman spectroscopy and laser-based materials processing to be performed in a transmission electron microscope. The system comprises a lensed Raman probe mounted inside the microscope column in the specimen plane and a custom specimen holder with a vacuum feedthrough for a tapered optical fiber. The Raman probe incorporates both excitation and collection optics, and localized laser processing is performed using pulsed laser light delivered to the specimen via the tapered optical fiber. Precise positioning of the fiber is achieved using a nanomanipulation stage in combination with simultaneous electron-beam imaging of the tip-to-sample distance. Materials modification is monitored in real time by transmission electron microscopy. First results obtained using the assembly are presented for in situ pulsed laser ablation of MoS 2 combined with Raman spectroscopy, complimented by electron-beam diffraction and electron energy-loss spectroscopy. Copyright © 2016 Elsevier B.V. All rights reserved.

Organization of projections from the anterior pole of the nucleus reticularis thalami (NRT) to subdivisions of the motor thalamus: light and electron microscopic studies in the rhesus monkey.

PubMed

Ilinsky, I A; Ambardekar, A V; Kultas-Ilinsky, K

1999-07-05

Projections to the motor-related thalamic nuclei from the anterior pole of the reticular thalamic nucleus (NRT) were studied after injections of biotinylated dextran amine and wheat germ agglutinin conjugated horseradish peroxidase at light and electron microscopic levels, respectively. Each injection resulted in anterograde labeling in the three subdivisions of the ventral anterior nucleus (pars parvicellularis, VApc; pars densicellularis, VAdc; and pars magnocellularis, VAmc) and in the ventral lateral nucleus (VL). NRT fibers had beaded shapes and coursed in a posterior direction giving rise to relatively diffuse terminal plexuses. The average size of the beads (0.7 microm2) and their density per 100 microm of fiber length (23.7-25.7) were similar between the nuclei studied. At the electron microscopic level, anterogradely labeled boutons displayed positive immunoreactivity for gamma-aminobutyric acid (GABA), contained pleomorphic synaptic vesicles, and formed relatively long (approximately 0.4 microm) symmetric synaptic contacts. Usually, a single terminal formed synapses on more than one postsynaptic structure. Synaptic contacts were on projection and local circuit neurons and targeted mainly their distal dendrites. In the VAmc, synapses on local circuit neurons composed 48% of the total sample, in the VAdc/VApc and in the VL the proportion was higher, 65% and 62%, respectively. The results suggest that the input from the anterior pole of the monkey reticular nucleus to the motor-related thalamic nuclei is organized differently from what is known on the organization of connections of NRT with sensory thalamic nuclei in other species in that the terminal fields of individual fibers are diffuse rather than focal and that at least 50% of synapses are established on GABAergic local circuit neurons.

Three-dimensional characterization of extreme ultraviolet mask blank defects by interference contrast photoemission electron microscopy.

PubMed

Lin, Jingquan; Weber, Nils; Escher, Matthias; Maul, Jochen; Han, Hak-Seung; Merkel, Michael; Wurm, Stefan; Schönhense, Gerd; Kleineberg, Ulf

2008-09-29

A photoemission electron microscope based on a new contrast mechanism "interference contrast" is applied to characterize extreme ultraviolet lithography mask blank defects. Inspection results show that positioning of interference destructive condition (node of standing wave field) on surface of multilayer in the local region of a phase defect is necessary to obtain best visibility of the defect on mask blank. A comparative experiment reveals superiority of the interference contrast photoemission electron microscope (Extreme UV illumination) over a topographic contrast one (UV illumination with Hg discharge lamp) in detecting extreme ultraviolet mask blank phase defects. A depth-resolved detection of a mask blank defect, either by measuring anti-node peak shift in the EUV-PEEM image under varying inspection wavelength condition or by counting interference fringes with a fixed illumination wavelength, is discussed.

High Dynamic Range Pixel Array Detector for Scanning Transmission Electron Microscopy.

PubMed

Tate, Mark W; Purohit, Prafull; Chamberlain, Darol; Nguyen, Kayla X; Hovden, Robert; Chang, Celesta S; Deb, Pratiti; Turgut, Emrah; Heron, John T; Schlom, Darrell G; Ralph, Daniel C; Fuchs, Gregory D; Shanks, Katherine S; Philipp, Hugh T; Muller, David A; Gruner, Sol M

2016-02-01

We describe a hybrid pixel array detector (electron microscope pixel array detector, or EMPAD) adapted for use in electron microscope applications, especially as a universal detector for scanning transmission electron microscopy. The 128×128 pixel detector consists of a 500 µm thick silicon diode array bump-bonded pixel-by-pixel to an application-specific integrated circuit. The in-pixel circuitry provides a 1,000,000:1 dynamic range within a single frame, allowing the direct electron beam to be imaged while still maintaining single electron sensitivity. A 1.1 kHz framing rate enables rapid data collection and minimizes sample drift distortions while scanning. By capturing the entire unsaturated diffraction pattern in scanning mode, one can simultaneously capture bright field, dark field, and phase contrast information, as well as being able to analyze the full scattering distribution, allowing true center of mass imaging. The scattering is recorded on an absolute scale, so that information such as local sample thickness can be directly determined. This paper describes the detector architecture, data acquisition system, and preliminary results from experiments with 80-200 keV electron beams.

Imaging the electron-boson coupling in superconducting FeSe films using a scanning tunneling microscope.

PubMed

Song, Can-Li; Wang, Yi-Lin; Jiang, Ye-Ping; Li, Zhi; Wang, Lili; He, Ke; Chen, Xi; Hoffman, Jennifer E; Ma, Xu-Cun; Xue, Qi-Kun

2014-02-07

Scanning tunneling spectroscopy has been used to reveal signatures of a bosonic mode in the local quasiparticle density of states of superconducting FeSe films. The mode appears below Tc as a "dip-hump" feature at energy Ω∼4.7kBTc beyond the superconducting gap Δ. Spectra on strained regions of the FeSe films reveal simultaneous decreases in Δ and Ω. This contrasts with all previous reports on other high-Tc superconductors, where Δ locally anticorrelates with Ω. A local strong coupling model is found to reconcile the discrepancy well, and to provide a unified picture of the electron-boson coupling in unconventional superconductors.

Size-dependent extravasation and interstitial localization of polyethyleneglycol liposomes in solid tumor-bearing mice.

PubMed

Ishida, O; Maruyama, K; Sasaki, K; Iwatsuru, M

1999-11-10

We have examined the size dependence of extravasation and interstitial localization of polyethyleneglycol-coated liposomes (PEG-liposomes) in the solid tumor tissue by means of electron microscopic observation. Liposomes composed of distearoyl phosphatidylcholine, cholesterol and distearoylphosphatidylethanolamine derivative of polyethyleneglycol (PEG) were prepared in various size ranges. PEG-liposomes with an average diameter of 100-200 nm showed the most prolonged circulation time and the greatest tumor accumulation in all the solid tumors employed in this experiment. Although large PEG-liposomes with a diameter of 400 nm showed a short circulation time in normal mice, the results in splenectomized mice indicated that they do have an intrinsic prolonged circulation character in vivo. However, large PEG-liposomes could not extravasate into solid tumor tissue. These results indicate that the size of liposomes is critical for extravasation. The electron microscopic observations revealed the almost exclusive engulfment of extravasated liposomes by tumor-associated macrophages; very few were taken up by tumor cells.

ELECTRON MICROSCOPIC LOCALIZATION OF ACETYLCHOLINESTERASE AND NONSPECIFIC CHOLINESTERASE AT THE NEUROMUSCULAR JUNCTION BY THE GOLD-THIOCHOLINE AND GOLD-THIOLACETIC ACID METHODS

PubMed Central

Davis, Richard; Koelle, George B.

1967-01-01

By means of the gold-thiocholine (AuThCh) and gold-thiolacetic acid (AuThAc) methods, it has been demonstrated electron microscopically that acetylcholinesterase (AChE) is located at the prejunctional axoplasmic membrane and the postjunctional sarcoplasmic membrane, including the full lengths of its invaginations, at the motor end plate of mouse intercostal muscle. Nonspecific cholinesterase (ChE) is present in relatively low concentrations at the same sites, and in greater concentrations in the teloglial Schwann sheath cells. Significant amounts of reaction product appeared in the junctional cleft only after prolonged incubation with both methods. The identification of AChE and ChE was confirmed by the use of appropriate concentrations of several selective inhibitors. In confirmation of previous studies by light microscopy, the AuThCh method is more specific for AChE and ChE, whereas the AuThAc method allows greater accuracy of localization. PMID:6033530

Imaging domain walls between nematic quantum Hall phases on the surface of bismuth

NASA Astrophysics Data System (ADS)

Ding, Hao; Randeria, Mallika T.; Feldman, Benjamin E.; Ji, Huiwen; Cava, Robert J.; Yazdani, Ali

The sensitivity of nematic electronic phases to disorder results in short range ordering and the formation of domains. Local probes are required to investigate the character of these domains and the boundaries between them, which remain hidden in global measurements that average over microscopic configurations. In this talk, I will describe measurements performed with a scanning tunneling microscope to study local nematic order on the surface of bismuth at high magnetic field. By imaging individual anisotropic cyclotron orbit wavefunctions that are pinned to atomic-scale surface defects, we directly resolve local nematic behavior and study the evolution of nematic states across a domain wall. Through spectroscopic mapping, we explore how the broken-symmetry Landau levels disperse across the domain wall, the influence of exchange interactions at such a boundary, and the formation of one-dimensional edge states.

Spectroscopic studies of nanomaterials with a liquid-helium-free high-stability cryogenic scanning tunneling microscope

NASA Astrophysics Data System (ADS)

Kislitsyn, Dmitry Anatolevich

This dissertation presents results of a project bringing Scanning Tunneling Microscope (STM) into a regime of unlimited operational time at cryogenic conditions. Freedom from liquid helium consumption was achieved and technical characteristics of the instrument are reported, including record low noise for a scanning probe instrument coupled to a close-cycle cryostat, which allows for atomically resolved imaging, and record low thermal drift. Subsequent studies showed that the new STM opened new prospects in nanoscience research by enabling Scanning Tunneling Spectroscopic (STS) spatial mapping to reveal details of the electronic structure in real space for molecules and low-dimensional nanomaterials, for which this depth of investigation was previously prohibitively expensive. Quantum-confined electronic states were studied in single-walled carbon nanotubes (SWCNTs) deposited on the Au(111) surface. Localization on the nanometer-scale was discovered to produce a local vibronic manifold resulting from the localization-enhanced electron-vibrational coupling. STS showed the vibrational overtones, identified as D-band Kekule vibrational modes and K-point transverse out-of plane phonons. This study experimentally connected the properties of well-defined localized electronic states to the properties of associated vibronic states. Electronic structures of alkyl-substituted oligothiophenes with different backbone lengths were studied and correlated with torsional conformations assumed on the Au(111) surface. The molecules adopted distinct planar conformations with alkyl ligands forming cis- or trans-mutual orientations and at higher coverage self-assembled into ordered structures, binding to each other via interdigitated alkyl ligands. STS maps visualized, in real space, particle-in-a-box-like molecular orbitals. Shorter quaterthiophenes have substantially varying orbital energies because of local variations in surface reactivity. Different conformers of longer oligothiophenes with significant geometrical distortions of the oligothiophene backbones surprisingly exhibited similar electronic structures, indicating insensitivity of interaction with the surface to molecular conformation. Electronic states for annealed ligand-free lead sulfide nanocrystals were investigated, as well as hydrogen-passivated silicon nanocrystals, supported on the Au(111) surface. Delocalized quantum-confined states and localized defect-related states were identified, for the first time, via STS spatial mapping. Physical mechanisms, involving surface reconstruction or single-atom defects, were proposed for surface state formation to explain the observed spatial behavior of the electronic density of states. This dissertation includes previously published co-authored material.

Bi-directional transmission of molecular information by photon or electron beams passing in the close vicinity of specific molecules, and its clinical and basic research applications: 1) Diagnosis of humans or animal patients without any direct contact; 2) Light microscopic and electron microscopic localization of neuro-transmitters, heavy metals, Oncogen C-fos (AB2), etc. of intracellular fine structures of normal and abnormal single cells using light or electro-microscopic indirect Bi-Digital O-Ring Test.

PubMed

Omura, Y; Losco, M; Omura, A K; Takeshige, C; Hisamitsu, T; Nakajima, H; Soejima, K; Yamamoto, S; Ishikawa, H; Kagoshima, T

1992-01-01

In 1985, Omura, Y. discovered that, when specific molecules were placed anywhere in the close vicinity of the path of a light beam (laser), their molecular information, as well as information on electrical & magnetic fields, is transmitted bi-directionally along the path of this light beam. Namely, this information is transmitted in the direction the light beam is projected and towards the direction from which the light beam is coming. This finding was applied to the following clinical and basic research: 1) In the past, using indirect Bi-Digital O-Ring Test, human or animal patients were diagnosed through an intermediate third person holding a good electrical conducting probe, the tip of which was touching the part of the patient to be examined. However, in order to diagnose the patient in isolation from a distance, or a dangerous or unmanagable unanesthesized animal, such as a lion or tiger, the author succeeded in making a diagnosis by replacing the metal conducting probe with a soft laser beam which is held by the one hand of the third person whose index finger is placed in close vicinity of the laser beam generated by a battery-powered penlight-type solid state laser generator. Thus, diagnosis within visible distance, without direct patient contact, became a reality. 2) Using a projection light microscope, by giving indirect Bi-Digital O-Ring Test while contacting with a fine electro-conductive probe on the magnified fine structure of normal and abnormal cells, various normal and abnormal intracellular substances were localized through a third person holding a pure reference control substance with the same hand that is holding the probe as an intermediary for the indirect Bi-Digital O-Ring Test. Instead of the photon beam in a light microscope, the author found that, using an electron beam passing through the close vicinity of specific molecules of specimens in an electron microscope, the molecular information is transmitted to the magnified fluorescent screen, and an indirect Bi-Digital O-Ring Test could be performed through a projected penlight-type solid state soft laser beam on the magnified intracellular structure through an observation glass window. Using the magnified fine structure of the cells, by either a light projection microscopic field or electron microscope, in various cancer cells of both humans and animals, Oncogen C-fos (AB2) and mercury were found inside of the nucleus. Integrin alpha 5 beta 1 was found on cell membranes and nuclear cell membranes of cancer cells. Acetylcholine was not found anywhere within cancer cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Nanoscale interplay of strain and doping in a high-temperature superconductor

DOE PAGES

Zeljkovic, Ilija; Gu, Genda; Nieminen, Jouko; ...

2014-11-07

The highest temperature superconductors are electronically inhomogeneous at the nanoscale, suggesting the existence of a local variable which could be harnessed to enhance the superconducting pairing. Here we report the relationship between local doping and local strain in the cuprate superconductor Bi₂Sr₂CaCu₂O₈₊ x. We use scanning tunneling microscopy to discover that the crucial oxygen dopants are periodically distributed, in correlation with local strain. Our picoscale investigation of the intra-unit-cell positions of all oxygen dopants provides essential structural input for a complete microscopic theory.

Ultrafast transmission electron microscopy using a laser-driven field emitter: Femtosecond resolution with a high coherence electron beam.

PubMed

Feist, Armin; Bach, Nora; Rubiano da Silva, Nara; Danz, Thomas; Möller, Marcel; Priebe, Katharina E; Domröse, Till; Gatzmann, J Gregor; Rost, Stefan; Schauss, Jakob; Strauch, Stefanie; Bormann, Reiner; Sivis, Murat; Schäfer, Sascha; Ropers, Claus

2017-05-01

We present the development of the first ultrafast transmission electron microscope (UTEM) driven by localized photoemission from a field emitter cathode. We describe the implementation of the instrument, the photoemitter concept and the quantitative electron beam parameters achieved. Establishing a new source for ultrafast TEM, the Göttingen UTEM employs nano-localized linear photoemission from a Schottky emitter, which enables operation with freely tunable temporal structure, from continuous wave to femtosecond pulsed mode. Using this emission mechanism, we achieve record pulse properties in ultrafast electron microscopy of 9Å focused beam diameter, 200fs pulse duration and 0.6eV energy width. We illustrate the possibility to conduct ultrafast imaging, diffraction, holography and spectroscopy with this instrument and also discuss opportunities to harness quantum coherent interactions between intense laser fields and free-electron beams. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Excitation of propagating surface plasmons with a scanning tunnelling microscope.

PubMed

Wang, T; Boer-Duchemin, E; Zhang, Y; Comtet, G; Dujardin, G

2011-04-29

Inelastic electron tunnelling excitation of propagating surface plasmon polaritons (SPPs) on a thin gold film is demonstrated. This is done by combining a scanning tunnelling microscope (STM) with an inverted optical microscope. Analysis of the leakage radiation in both the image and Fourier planes unambiguously shows that the majority (up to 99.5%) of the detected photons originate from propagating SPPs with propagation lengths of the order of 10  µm. The remaining photon emission is localized under the STM tip and is attributed to a tip-gold film coupled plasmon resonance as evidenced by the bimodal spectral distribution and enhanced emission intensity observed using a silver STM tip for excitation.

A unifying approach to lattice dynamical and electronic properties of solids

NASA Astrophysics Data System (ADS)

Falter, C.

1988-06-01

A unified analysis of lattice dynamical and electronic properties of solids with special emphasis on the interaction between electrons and phonons is presented. The article is roughly divided into two parts reflecting different points of view. The density response of the electrons provides the link between these parts. In the first part, the microscopic theory in terms of the density response in crystals is discussed. Relations are pointed out between the density response approach and the density functional theory. The latter is used for a representation of the exchange-correlation interaction and the microscopic force constants. Relevant methods, as recently proposed by various authors for the calculation of the density response in inhomogeneous solids are discussed. Particular attention is paid to the development of a renormalized response description. Applications of this method to lattice dynamical and electronic properties are presented. In the second part an alternative physical concept, the quasi-ion approach, is outlined. This concept is shown to provide a microscopic basis for electronic charge localization in crystals and proves the importance of the correlation between crystal symmetry and many-body effects. Is is derived that within linear response theory an appropriate decomposition of the valence charge density leads uniquely to a spatially localized density contribution at the individual ion which follows its motion rigidly. The composite consisting of this partial density and the ion core is taken to be an individual entity, denoted as quasi-ion, from which the crystal is built up. In a certain sense this is a generalization of Ziman's concept of neutral pseudo-atoms being approximately valid in simple metals. New insight into the bonding mechanism and charge relaxation processes is shown to follow from this concept. In particular, we discuss the covalent, ionic and metallic bonding mechanisms, using the localized picture provided by the partial densities, on the same basis. The quasi-ion approach is also applied to the calculation of phonon-induced charge density redistributions and to the construction of a simplified formulation of microscopic lattice dynamics. Investigations of the phonon dispersion for different bonding types are given within a rigid quasi-ion model and extensions of this model are outlined. Among other things, these calculations indicate that bonding dynamics of (covalent) molecules and crystals can be described by relative rotations of the quasi-ions under the condition of rotational invariance of the system. Finally, possible applications of the quasi-ion concept to an approximate formulation of anharmonic lattice dynamics and the interaction between electrons and phonons are discussed. A numerical investigation of this interaction is presented and compared with the results from the rigid-ion model. As a consequence of the quasi-ion concept a consistent calculation of the phonon dispersion, the electronic band structure and the electron-phonon interaction becomes possible.

Science 101: How Does an Electron Microscope Work?

ERIC Educational Resources Information Center

Robertson, Bill

2013-01-01

Contrary to popular opinion, electron microscopes are not used to look at electrons. They are used to look for structure in things that are too small to observe with an optical microscope, or to obtain images that are magnified much more than is obtainable with an optical microscope. To understand how electron microscopes work, it will help to go…

Depopulation of Single-Phthalocyanine Molecular Orbitals upon Pyrrolic-Hydrogen Abstraction on Graphene.

PubMed

Néel, Nicolas; Lattelais, Marie; Bocquet, Marie-Laure; Kröger, Jörg

2016-02-23

Single-molecule chemistry with a scanning tunneling microscope has preponderantly been performed on metal surfaces. The molecule-metal hybridization, however, is often detrimental to genuine molecular properties and obscures their changes upon chemical reactions. We used graphene on Ir(111) to reduce the coupling between Ir(111) and adsorbed phthalocyanine molecules. By local electron injection from the tip of a scanning tunneling microscope the two pyrrolic H atoms were removed from single phthalocyanines. The detachment of the H atom pair induced a strong modification of the molecular electronic structure, albeit with no change in the adsorption geometry. Spectra and maps of the differential conductance combined with density functional calculations unveiled the entire depopulation of the highest occupied molecular orbital upon H abstraction. Occupied π states of intact molecules are proposed to be emptied via intramolecular electron transfer to dangling σ states of H-free N atoms.

SEM visualization of glycosylated surface molecules using lectin-coated microspheres

NASA Technical Reports Server (NTRS)

Duke, J.; Janer, L.; Campbell, M.

1985-01-01

There are several techniques currently used to localize glycosylated surface molecules by scanning electron microscopy (Grinnell, 1980; Molday, 1976; Linthicum and Sell, 1975; Nicolson, 1974; Lo Buglio, et al, 1972). A simple and rapid method, using a modification of Grinnell's technique is reported here. Essentially, microspheres coated with Concavalin A are used to bind to glycosylated regions of the palatal shelf epithelium and are visualized in the scanning electron microscope (SEM).

Localization of nucleolar chromatin by immunocytochemistry and in situ hybridization at the electron microscopic level.

PubMed

Thiry, M; Scheer, U; Goessens, G

1991-01-01

Nucleoli are the morphological expression of the activity of a defined set of chromosomal segments bearing rRNA genes. The topological distribution and composition of the intranucleolar chromatin as well as the definition of nucleolar structures in which enzymes of the rDNA transcription machinery reside have been investigated in mammalian cells by various immunogold labelling approaches at the ultrastructural level. The precise intranucleolar location of rRNA genes has been further specified by electron microscopic in situ hybridization with a non-autoradiographic procedure. Our results indicate that the fibrillar centers are the sole nucleolar structures where rDNA, core histones, RNA polymerase I and DNA topoisomerase I are located together. Taking into account the potential value and limitations of immunoelectron microscopic techniques, we propose that transcription of the rRNA genes takes place within the confines of the fibrillar centers, probably close to the boundary regions to the surrounding dense fibrillar component.

Dynamic nano-imaging of label-free living cells using electron beam excitation-assisted optical microscope

PubMed Central

Fukuta, Masahiro; Kanamori, Satoshi; Furukawa, Taichi; Nawa, Yasunori; Inami, Wataru; Lin, Sheng; Kawata, Yoshimasa; Terakawa, Susumu

2015-01-01

Optical microscopes are effective tools for cellular function analysis because biological cells can be observed non-destructively and non-invasively in the living state in either water or atmosphere condition. Label-free optical imaging technique such as phase-contrast microscopy has been analysed many cellular functions, and it is essential technology for bioscience field. However, the diffraction limit of light makes it is difficult to image nano-structures in a label-free living cell, for example the endoplasmic reticulum, the Golgi body and the localization of proteins. Here we demonstrate the dynamic imaging of a label-free cell with high spatial resolution by using an electron beam excitation-assisted optical (EXA) microscope. We observed the dynamic movement of the nucleus and nano-scale granules in living cells with better than 100 nm spatial resolution and a signal-to-noise ratio (SNR) around 10. Our results contribute to the development of cellular function analysis and open up new bioscience applications. PMID:26525841

Dynamic nano-imaging of label-free living cells using electron beam excitation-assisted optical microscope.

PubMed

Fukuta, Masahiro; Kanamori, Satoshi; Furukawa, Taichi; Nawa, Yasunori; Inami, Wataru; Lin, Sheng; Kawata, Yoshimasa; Terakawa, Susumu

2015-11-03

Optical microscopes are effective tools for cellular function analysis because biological cells can be observed non-destructively and non-invasively in the living state in either water or atmosphere condition. Label-free optical imaging technique such as phase-contrast microscopy has been analysed many cellular functions, and it is essential technology for bioscience field. However, the diffraction limit of light makes it is difficult to image nano-structures in a label-free living cell, for example the endoplasmic reticulum, the Golgi body and the localization of proteins. Here we demonstrate the dynamic imaging of a label-free cell with high spatial resolution by using an electron beam excitation-assisted optical (EXA) microscope. We observed the dynamic movement of the nucleus and nano-scale granules in living cells with better than 100 nm spatial resolution and a signal-to-noise ratio (SNR) around 10. Our results contribute to the development of cellular function analysis and open up new bioscience applications.

Dynamic nano-imaging of label-free living cells using electron beam excitation-assisted optical microscope

NASA Astrophysics Data System (ADS)

Fukuta, Masahiro; Kanamori, Satoshi; Furukawa, Taichi; Nawa, Yasunori; Inami, Wataru; Lin, Sheng; Kawata, Yoshimasa; Terakawa, Susumu

2015-11-01

Optical microscopes are effective tools for cellular function analysis because biological cells can be observed non-destructively and non-invasively in the living state in either water or atmosphere condition. Label-free optical imaging technique such as phase-contrast microscopy has been analysed many cellular functions, and it is essential technology for bioscience field. However, the diffraction limit of light makes it is difficult to image nano-structures in a label-free living cell, for example the endoplasmic reticulum, the Golgi body and the localization of proteins. Here we demonstrate the dynamic imaging of a label-free cell with high spatial resolution by using an electron beam excitation-assisted optical (EXA) microscope. We observed the dynamic movement of the nucleus and nano-scale granules in living cells with better than 100 nm spatial resolution and a signal-to-noise ratio (SNR) around 10. Our results contribute to the development of cellular function analysis and open up new bioscience applications.

Initation of pitting corrosion in martensitic stainless steels. [17-4PH; 13-8Mo; Custom 450

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cieslak, W.R.; Semarge, R.E.; Bovard, F.S.

1986-01-01

The form of localized corrosion known as pitting often initiates preferentially at microstructural inhomogeneities. The pit initiation resistance, therefore, is controlled by the characteristics of the initiation sites, rather than by the bulk material composition. This investigation correlates the pit initiation resistance, as measured by critical pitting potentials, with preferred pit initiation sites for 3 martensitic stainless steels. Pit initiation sites are determined by secondary electron (SE) and backscattered electron (BSE) imaging and energy dispersive and wavelength dispersive spectrometries (EDS and WDS) with a scalling electron microscope (SEM) and an electron probe microanalyzer (EPMA).

In situ observation of electron beam-induced phase transformation of CaCO3 to CaO via ELNES at low electron beam energies.

PubMed

Golla-Schindler, Ute; Benner, Gerd; Orchowski, Alexander; Kaiser, Ute

2014-06-01

It is demonstrated that energy-filtered transmission electron microscope enables following of in situ changes of the Ca-L2,3 edge which can originate from variations in both local symmetry and bond lengths. Low accelerating voltages of 20 and 40 kV slow down radiation damage effects and enable study of the start and finish of phase transformations. We observed electron beam-induced phase transformation of single crystalline calcite (CaCO3) to polycrystalline calcium oxide (CaO) which occurs in different stages. The coordination of Ca in calcite is close to an octahedral one streched along the <111> direction. Changes during phase transformation to an octahedral coordination of Ca in CaO go along with a bond length increase by 5 pm, where oxygen is preserved as a binding partner. Electron loss near-edge structure of the Ca-L2,3 edge show four separated peaks, which all shift toward lower energies during phase transformation at the same time the energy level splitting increases. We suggest that these changes can be mainly addressed to the change of the bond length on the order of picometers. An important pre-condition for such studies is stability of the energy drift in the range of meV over at least 1 h, which is achieved with the sub-Ångström low-voltage transmission electron microscope I prototype microscope.

Microscopic origin of magnetism and magnetic interactions in ferropnictides

NASA Astrophysics Data System (ADS)

Johannes, M. D.; Mazin, I. I.

2009-06-01

One year after their initial discovery, two schools of thought have crystallized regarding the electronic structure and magnetic properties of ferropnictide systems. One postulates that these are itinerant weakly correlated metallic systems that become magnetic by virtue of spin-Peierls-type transition due to near nesting between the hole and the electron Fermi-surface pockets. The other argues that these materials are strongly or at least moderately correlated and the electrons are considerably localized and close to a Mott-Hubbard transition, with the local magnetic moments interacting via short-range superexchange. In this Rapid Communication we argue that neither picture is fully correct. The systems are moderately correlated but with correlations driven by Hund’s rule coupling rather than by the on-site Hubbard repulsion. The iron moments are largely local, driven by Hund’s intra-atomic exchange. Superexchange is not operative, and the interactions between the Fe moments are considerably long range and driven mostly by one-electron energies of all occupied states.

Evaluation of Encapsulated Inhibitor for Autonomous Corrosion Protection

NASA Technical Reports Server (NTRS)

Johnsey, M. N.; Li, W.; Buhrow, J. W.; Calle, L. M.; Pearman, B. P.; Zhang, X.

2015-01-01

This work concerns the development of smart coating technologies based on microencapsulation for the autonomous control of corrosion. Microencapsulation allows the incorporation of corrosion inhibitors into coating which provides protection through corrosion-controlled release of these inhibitors.One critical aspect of a corrosion protective smart coating is the selection of corrosion inhibitor for encapsulation and comparison of the inhibitor function before and after encapsulation. For this purpose, a systematic approach is being used to evaluate free and encapsulated corrosion inhibitors by salt immersion. Visual, optical microscope, and Scanning Electron Microscope (with low-angle backscatter electron detector) are used to evaluate these inhibitors. It has been found that the combination of different characterization tools provide an effective method for evaluation of early stage localized corrosion and the effectiveness of corrosion inhibitors.

Comparative study of image contrast in scanning electron microscope and helium ion microscope.

PubMed

O'Connell, R; Chen, Y; Zhang, H; Zhou, Y; Fox, D; Maguire, P; Wang, J J; Rodenburg, C

2017-12-01

Images of Ga + -implanted amorphous silicon layers in a 110 n-type silicon substrate have been collected by a range of detectors in a scanning electron microscope and a helium ion microscope. The effects of the implantation dose and imaging parameters (beam energy, dwell time, etc.) on the image contrast were investigated. We demonstrate a similar relationship for both the helium ion microscope Everhart-Thornley and scanning electron microscope Inlens detectors between the contrast of the images and the Ga + density and imaging parameters. These results also show that dynamic charging effects have a significant impact on the quantification of the helium ion microscope and scanning electron microscope contrast. © 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.

Identifying local characteristic lengths governing sound wave properties in solid foams

NASA Astrophysics Data System (ADS)

Tan Hoang, Minh; Perrot, Camille

2013-02-01

Identifying microscopic geometric properties and fluid flow through opened-cell and partially closed-cell solid structures is a challenge for material science, in particular, for the design of porous media used as sound absorbers in building and transportation industries. We revisit recent literature data to identify the local characteristic lengths dominating the transport properties and sound absorbing behavior of polyurethane foam samples by performing numerical homogenization simulations. To determine the characteristic sizes of the model, we need porosity and permeability measurements in conjunction with ligament lengths estimates from available scanning electron microscope images. We demonstrate that this description of the porous material, consistent with the critical path picture following from the percolation arguments, is widely applicable. This is an important step towards tuning sound proofing properties of complex materials.

Detection of microstructural defects in chalcopyrite Cu(In,Ga)Se2 solar cells by spectrally-filtered electroluminescence

NASA Astrophysics Data System (ADS)

Skvarenina, L.; Gajdos, A.; Macku, R.; Skarvada, P.

2017-12-01

The aim of this research is to detect and localize microstructural defects by using an electrically excited light emission from a forward/reverse-bias stressed pn-junction in thin-film Cu(In; Ga)Se2 solar cells with metal wrap through architecture. A different origin of the local light emission from intrinsic/extrinsic imperfections in these chalcopyrite-based solar cells can be distinguished by a spectrally-filtered electroluminescence mapping. After a light emission mapping and localization of the defects in a macro scale is performed a micro scale exploration of the solar cell surface by a scanning electron microscope which follows the particular defects obtained by an electroluminescence. In particular, these macroscopic/microscopic examinations are performed independently, then the searching of the corresponding defects in the micro scale is rather difficult due to a diffused light emission obtained from the macro scale localization. Some of the defects accompanied by a highly intense light emission very often lead to a strong local overheating. Therefore, the lock-in infrared thermography is also performed along with an electroluminescence mapping.

Atomic-scale luminescence measurement and theoretical analysis unveiling electron energy dissipation at a p-type GaAs(110) surface.

PubMed

Imada, Hiroshi; Miwa, Kuniyuki; Jung, Jaehoon; Shimizu, Tomoko K; Yamamoto, Naoki; Kim, Yousoo

2015-09-11

Luminescence of p-type GaAs was induced by electron injection from the tip of a scanning tunnelling microscope into a GaAs(110) surface. Atomically-resolved photon maps revealed a significant reduction in luminescence intensity at surface electronic states localized near Ga atoms. Theoretical analysis based on first principles calculations and a rate equation approach was performed to describe the perspective of electron energy dissipation at the surface. Our study reveals that non-radiative recombination through the surface states (SS) is a dominant process for the electron energy dissipation at the surface, which is suggestive of the fast scattering of injected electrons into the SS.

Development of SEM/STEM-WDX for highly sensitive detection of light elements

NASA Astrophysics Data System (ADS)

Anan, Y.; Koguchi, M.; Kimura, T.; Sekiguchi, T.

2018-02-01

In this study, to detect the light element lithium (Li) and to detect low dosed Boron (B) in the local area at nm order, we developed an analytical electron microscope equipped with an improved serial (S)-type WDX (wavelength dispersive X-ray spectroscopy) system. In detail, to detect Li, we developed a high-conductivity multi-capillary X-ray (MCX) lens, and a diffractor with a lattice spacing (d) of 15 nm, and with a spacing variation (δ d) of 0.8 nm. Moreover, to detect low dosed light element B, we designed a high-conductivity MCX lens based on the soft X-ray reflectivity in the capillary and calculation. We developed a large-solid-angle MCX lens whose conductivity of the characteristic X-rays of B became 20 times higher than that of an MCX lens with a 30-mm focal length. Our developed analytical electron microscope was applied to a LiAl specimen and a low B-doped Si substrate specimen, and the performance of this analytical electron microscope was evaluated. As a results, this analytical electron microscope could detect the characteristic X-rays of Li with a minimum mass fraction (MMF) of 8.4 atomic % (at. %). The energy resolution was 1 eV at 55 eV. From the results of measuring the line profile of B for the unpatterned B-implantation area on a B-doped Si substrate specimen, the measured line profile data were in good agreement with secondary ion mass spectrometry data up to a depth of 100 nm with a B concentration of 0.05 at. %.

A study of over production and enhanced secretion of enzymes. Quarterly report 1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dashek, W.V.

1992-12-28

The current project is concerned with the over-production and enhanced secretion of PPO, cellulase and lignin peroxidase. The project is divided into two segments: over-production of lignocellulolytic enzymes by genetic engineering methodologies and hyper-production and enhanced secretion of these enzymes by biochemical/electron microscopical techniques. The former approach employs recombinant DNA procedures, ligation of appropriate nuclease generated DNA fragments into a vector and the subsequent transformation of Escherichia coli to yield E. coli harboring a C. versicolor DNA insert. The biochemistry/electron microscopical method involves substrate induction and the time-dependent addition of respiration and PPO inhibitors to elevate C.versicolor`s ability to synthesizemore » and secrete lignocellulosic enzymes. In this connection, cell fractionation/kinetic analysis, TEM immunoelectron microscopic localization and TEM substrate localization of PPO are being employed to assess the route of secretion. Both approaches will culminate in the batch culture of either E. coli or C. versicolor, in a fermentor with the subsequent development of rapid isolation and purification procedures to yield elevated quantities of pure lignocellulosic enzymes. During the past year, research effort were directed toward determining the route of polyphenol oxidase (PPO) secretion by the wood-decay fungus, Coriolus versicolor. In addition, research activities were continued to over-produce and to purify PPO as well as define the time-dependent intra- and extra-cellular appearances of C. versicolor ligninases and cellulases.« less

Large area fabrication of plasmonic nanoparticle grating structure by conventional scanning electron microscope

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sudheer,, E-mail: sudheer@rrcat.gov.in; Tiwari, P.; Rai, V. N.

Plasmonic nanoparticle grating (PNG) structure of different periods has been fabricated by electron beam lithography using silver halide based transmission electron microscope film as a substrate. Conventional scanning electron microscope is used as a fabrication tool for electron beam lithography. Optical microscope and energy dispersive spectroscopy (EDS) have been used for its morphological and elemental characterization. Optical characterization is performed by UV-Vis absorption spectroscopic technique.

Spontaneous breaking of time-reversal symmetry in strongly interacting two-dimensional electron layers in silicon and germanium.

PubMed

Shamim, S; Mahapatra, S; Scappucci, G; Klesse, W M; Simmons, M Y; Ghosh, A

2014-06-13

We report experimental evidence of a remarkable spontaneous time-reversal symmetry breaking in two-dimensional electron systems formed by atomically confined doping of phosphorus (P) atoms inside bulk crystalline silicon (Si) and germanium (Ge). Weak localization corrections to the conductivity and the universal conductance fluctuations were both found to decrease rapidly with decreasing doping in the Si:P and Ge:P delta layers, suggesting an effect driven by Coulomb interactions. In-plane magnetotransport measurements indicate the presence of intrinsic local spin fluctuations at low doping, providing a microscopic mechanism for spontaneous lifting of the time-reversal symmetry. Our experiments suggest the emergence of a new many-body quantum state when two-dimensional electrons are confined to narrow half-filled impurity bands.

Tip-induced local strain on Mo S 2 / graphite detected by inelastic electron tunneling spectroscopy

DOE PAGES

Ko, Wonhee; Hus, Saban M.; Li, Xufan; ...

2018-03-02

We report the detection of tip-induced local strain applied to the monolayer MoS 2 grown on a graphite substrate by scanning tunneling microscope. Monolayer MoS 2 behaves as both mechanical and tunneling barriers that prevent the tip from contacting the graphite while maintaining the tunneling current. Inelastic tunneling electron spectroscopy (IETS) is utilized to probe the phonon modes in graphite. As the tip pushes the sample, IETS reveals a continuous phonon softening in graphite, corroborated by a downward shift of the phonon energy as calculated by density-functional theory. Finally, our results demonstrate a way to apply local mechanical strain andmore » simultaneously detect the induced change in phonon modes by unitizing IETS with two-dimensional materials as a tunneling barrier.« less

Tip-induced local strain on Mo S 2 / graphite detected by inelastic electron tunneling spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ko, Wonhee; Hus, Saban M.; Li, Xufan

We report the detection of tip-induced local strain applied to the monolayer MoS 2 grown on a graphite substrate by scanning tunneling microscope. Monolayer MoS 2 behaves as both mechanical and tunneling barriers that prevent the tip from contacting the graphite while maintaining the tunneling current. Inelastic tunneling electron spectroscopy (IETS) is utilized to probe the phonon modes in graphite. As the tip pushes the sample, IETS reveals a continuous phonon softening in graphite, corroborated by a downward shift of the phonon energy as calculated by density-functional theory. Finally, our results demonstrate a way to apply local mechanical strain andmore » simultaneously detect the induced change in phonon modes by unitizing IETS with two-dimensional materials as a tunneling barrier.« less

Tip-induced local strain on Mo S2/graphite detected by inelastic electron tunneling spectroscopy

NASA Astrophysics Data System (ADS)

Ko, Wonhee; Hus, Saban M.; Li, Xufan; Berlijn, Tom; Nguyen, Giang D.; Xiao, Kai; Li, An-Ping

2018-03-01

We report the detection of tip-induced local strain applied to the monolayer Mo S2 grown on a graphite substrate by scanning tunneling microscope. Monolayer Mo S2 behaves as both mechanical and tunneling barriers that prevent the tip from contacting the graphite while maintaining the tunneling current. Inelastic tunneling electron spectroscopy (IETS) is utilized to probe the phonon modes in graphite. As the tip pushes the sample, IETS reveals a continuous phonon softening in graphite, corroborated by a downward shift of the phonon energy as calculated by density-functional theory. Our results demonstrate a way to apply local mechanical strain and simultaneously detect the induced change in phonon modes by unitizing IETS with two-dimensional materials as a tunneling barrier.

Transmission electron microscope CCD camera

DOEpatents

Downing, Kenneth H.

1999-01-01

In order to improve the performance of a CCD camera on a high voltage electron microscope, an electron decelerator is inserted between the microscope column and the CCD. This arrangement optimizes the interaction of the electron beam with the scintillator of the CCD camera while retaining optimization of the microscope optics and of the interaction of the beam with the specimen. Changing the electron beam energy between the specimen and camera allows both to be optimized.

Controlled electron doping into metallic atomic wires: Si(111)4×1-In

NASA Astrophysics Data System (ADS)

Morikawa, Harumo; Hwang, C. C.; Yeom, Han Woong

2010-02-01

We demonstrate the controllable electron doping into metallic atomic wires, indium wires self-assembled on the Si(111) surface, which feature one-dimensional (1D) band structure and temperature-driven metal-insulator transition. The electron filling of 1D metallic bands is systematically increased by alkali-metal adsorption, which, in turn, tunes the macroscopic property, that is, suppresses the metal-insulator transition. On the other hand, the dopant atoms induce a local lattice distortion without a band-gap opening, leading to a microscopic phase separation on the surface. The distinct bifunctional, electronic and structural, roles of dopants in different length scales are thus disclosed.

Dynamic evolutions of electron properties: A theoretical study for condensed-phase β-HMX under shock loading

NASA Astrophysics Data System (ADS)

He, Zheng-Hua; Chen, Jun; Wu, Qiang; Ji, Guang-Fu

2017-11-01

We present the density functional theory (DFT) calculations for microscopic electron properties of β-HMX under shock loading. The metallization pressure is determined to be within 30-55 GPa. The frontier molecular orbitals mainly localize on N-NO2 groups initially and disperse with pressure increase, while HOMO and LUMO orbitals trend to aggregate with each other. The deformation of N-NO2 groups and enhanced hydrogen-bonding interactions cause the electron delocalization and lower the band gap, inducing the reaction initiation finally. Our results show that using the electron properties can reliably predict the initial decomposition of energetic materials under shock loading.

76 FR 65696 - Battelle Energy Alliance, et al.;

Federal Register 2010, 2011, 2012, 2013, 2014

2011-10-24

... of Texas at Austin, Austin, TX 78712. Instrument: Electron Microscope. Manufacturer: FEI Company, the... research or scientific educational uses requiring an electron microscope. We know of no electron microscope...

Immunohistochemical localization of FMRFamide-containing neurons and nerve fibers in the ganglia and the gonad wall of the scallop, Pecten maximus (L).

PubMed

Henry, M; Benlinmame, N; Belhsen, O K; Jule, Y; Mathieu, M

1995-02-01

The Phe-Met-Arg-Phe NH2 (FMRFamide)-like immunoreactivity was detected in neurons of the cerebro-pedal and visceral ganglia of the scallop Pecten maximus using immunohistochemical techniques. FMRFamide-like immunoreactivity was also found in nerve fibers localized in the connective tissue and the epithelial wall of the gonad. Electron microscopy study carried out on the gonads indicates the existence of numerous nerve fibers crossing the connective tissue; nerve terminals apposed to highly secretory cells were seen in the gonad wall. All in all, the present immunohistochemical and electron microscopic data suggest that FMRFamide might play an unusual secretagogue role in the gonad wall.

Local dynamic range compensation for scanning electron microscope imaging system by sub-blocking multiple peak HE with convolution.

PubMed

Sim, K S; Teh, V; Tey, Y C; Kho, T K

2016-11-01

This paper introduces new development technique to improve the Scanning Electron Microscope (SEM) image quality and we name it as sub-blocking multiple peak histogram equalization (SUB-B-MPHE) with convolution operator. By using this new proposed technique, it shows that the new modified MPHE performs better than original MPHE. In addition, the sub-blocking method consists of convolution operator which can help to remove the blocking effect for SEM images after applying this new developed technique. Hence, by using the convolution operator, it effectively removes the blocking effect by properly distributing the suitable pixel value for the whole image. Overall, the SUB-B-MPHE with convolution outperforms the rest of methods. SCANNING 38:492-501, 2016. © 2015 Wiley Periodicals, Inc. © Wiley Periodicals, Inc.

Cellular localization of Na(+), K(+)-ATPase in the mammalian vestibular system

NASA Technical Reports Server (NTRS)

Kerr, T. P.

1984-01-01

Two different, but complementary, procedures for cellular localization of Na+, K+-ATPase in the guinea pig vestibular system were employed. One of these techniques, devised by Stirling, depends upon the well documented ability of the specific inhibitor ouabain to bind selectively to Na+,K+-ATPase, blocking catalytic activity. Microdisected vestibular tissues are incubated with tritium-labelled (3H-) ouabain, and regions with a high concentration of Na+,K+-ATPase are subsequently identified by light microscope autoradiography. A second method, originated by Ernst, detects inorganic phosphate released from an artificial substrate (nitrophenyl phosphate) by catalytic activity of the enzyme. In the presence of strontium ion, phosphate is precipitated near regions of high activity, then converted to a product which may finally be visualized in the electron microscope. This cytochemical enzymatic reaction is inhibited by ouabain.

Importance of conduction electron correlation in a Kondo lattice, Ce₂CoSi₃.

PubMed

Patil, Swapnil; Pandey, Sudhir K; Medicherla, V R R; Singh, R S; Bindu, R; Sampathkumaran, E V; Maiti, Kalobaran

2010-06-30

Kondo systems are usually described by the interaction of the correlation induced local moments with the highly itinerant conduction electrons. Here, we study the role of electron correlations among conduction electrons in the electronic structure of a Kondo lattice compound, Ce₂CoSi₃, using high resolution photoemission spectroscopy and ab initio band structure calculations, where Co 3d electrons contribute in the conduction band. High energy resolution employed in the measurements helped to reveal the signatures of Ce 4f states derived Kondo resonance features at the Fermi level and the dominance of Co 3d contributions at higher binding energies in the conduction band. The lineshape of the experimental Co 3d band is found to be significantly different from that obtained from the band structure calculations within the local density approximations, LDA. Consideration of electron-electron Coulomb repulsion, U, among Co 3d electrons within the LDA + U method leads to a better representation of experimental results. The signature of an electron correlation induced satellite feature is also observed in the Co 2p core level spectrum. These results clearly demonstrate the importance of the electron correlation among conduction electrons in deriving the microscopic description of such Kondo systems.

Localization of nitric oxide synthase and NADPH-diaphorase in guinea pig and human cochleae.

PubMed

Ruan, R S; Leong, S K; Yeoh, K H

1997-01-01

The distributions of nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) and nitric oxide synthase (NOS) in mammalian cochlea were studied at light and electron microscope levels by NADPH-d histochemistry and brain NOS (bNOS) immunohistochemistry. The cochleae from 15 albino guinea pigs were perilymphatically fixed with 2% periodate-lysine-paraformaldehyde, decalcified in 10% EDTA and processed for light and electron microscopy after NADPH-d or NOS staining in frozen and vibratome sections respectively. One human cochlea was available for light microscope examination of NADPH-d or bNOS stained sections. Light microscope results revealed that type I neurons and nerve fibers of the spiral ganglion cells were labeled by bNOS immunohistochemistry as well as NADPH-d histochemistry in both guinea pig and human cochleae. At subcellular level, NADPH-d reaction product was localized in the mitochondria of the neuronal cytoplasm and axoplasm and in the cytoplasm of the vascular endothelium. The immunoreaction products of bNOS were evenly distributed in the neuronal cytoplasm and axoplasm. Myelinated and unmyelinated fibers in the intraganglionic spiral bundle and the inner spiral and inner radial fibers below the inner hair cells were labeled for bNOS. The nerve endings below the outer hair cells were not stained. NOS immunoreaction product was also found in the outer hair cells, Schwann cells of myelinated nerve fibers, Deiter's cells, pillar cells and the tympanic lamina cells. No difference was found in the staining pattern of both NADPH-d and NOS reaction products between human and guinea pig cochleae at the light microscope level. The results suggest that NO plays an important role in the maintenance of auditory function in the mammal.

Microscopic studies of the fate of charges in organic semiconductors: Scanning Kelvin probe measurements of charge trapping, transport, and electric fields in p- and n-type devices

NASA Astrophysics Data System (ADS)

Smieska, Louisa Marion

Organic semiconductors could have wide-ranging applications in lightweight, efficient electronic circuits. However, several fundamental questions regarding organic electronic device behavior have not yet been fully addressed, including the nature of chemical charge traps, and robust models for injection and transport. Many studies focus on engineering devices through bulk transport measurements, but it is not always possible to infer the microscopic behavior leading to the observed measurements. In this thesis, we present scanning-probe microscope studies of organic semiconductor devices in an effort to connect local properties with local device behavior. First, we study the chemistry of charge trapping in pentacene transistors. Working devices are doped with known pentacene impurities and the extent of charge trap formation is mapped across the transistor channel. Trap-clearing spectroscopy is employed to measure an excitation of the pentacene charge trap species, enabling identification of the degradationrelated chemical trap in pentacene. Second, we examine transport and trapping in peryelene diimide (PDI) transistors. Local mobilities are extracted from surface potential profiles across a transistor channel, and charge injection kinetics are found to be highly sensitive to electrode cleanliness. Trap-clearing spectra generally resemble PDI absorption spectra, but one derivative yields evidence indicating variation in trap-clearing mechanisms for different surface chemistries. Trap formation rates are measured and found to be independent of surface chemistry, contradicting a proposed silanol trapping mechanism. Finally, we develop a variation of scanning Kelvin probe microscopy that enables measurement of electric fields through a position modulation. This method avoids taking a numeric derivative of potential, which can introduce high-frequency noise into the electric field signal. Preliminary data is presented, and the theoretical basis for electric field noise in both methods is examined.

AB INITIO Molecular Dynamics Simulations on Local Structure and Electronic Properties in Liquid MgxBi1-x Alloys

NASA Astrophysics Data System (ADS)

Hao, Qing-Hai; You, Yu-Wei; Kong, Xiang-Shan; Liu, C. S.

2013-03-01

The microscopic structure and dynamics of liquid MgxBi1-x(x = 0.5, 0.6, 0.7) alloys together with pure liquid Mg and Bi metals were investigated by means of ab initio molecular dynamics simulations. We present results of structure properties including pair correlation function, structural factor, bond-angle distribution function and bond order parameter, and their composition dependence. The dynamical and electronic properties have also been studied. The structure factor and pair correlation function are in agreement with the available experimental data. The calculated bond-angle distribution function and bond order parameter suggest that the stoichiometric composition Mg3Bi2 exhibits a different local structure order compared with other concentrations, which help us understand the appearance of the minimum electronic conductivity at this composition observed in previous experiments.

Localization and oscillations of Majorana fermions in a two-dimensional electron gas coupled with d -wave superconductors

NASA Astrophysics Data System (ADS)

Ortiz, L.; Varona, S.; Viyuela, O.; Martin-Delgado, M. A.

2018-02-01

We study the localization and oscillation properties of the Majorana fermions that arise in a two-dimensional electron gas (2DEG) with spin-orbit coupling (SOC) and a Zeeman field coupled with a d -wave superconductor. Despite the angular dependence of the d -wave pairing, localization and oscillation properties are found to be similar to the ones seen in conventional s -wave superconductors. In addition, we study a microscopic lattice version of the previous system that can be characterized by a topological invariant. We derive its real space representation that involves nearest and next-to-nearest-neighbors pairing. Finally, we show that the emerging chiral Majorana fermions are indeed robust against static disorder. This analysis has potential applications to quantum simulations and experiments in high-Tc superconductors.

Charge injection and transport in a single organic monolayer island

NASA Astrophysics Data System (ADS)

Vuillaume, Dominique

2005-03-01

We report how electrons and holes, that are locally injected in a single organic monolayer island (where organic monolayers are made from sublimated oligomers (pentacene and other oligoacenes), or made from chemisorption in solution (self-assembled monolayers) of pi-conjugated moieties), stay localized or are able to delocalize over the island as a function of the molecular conformation (order vs. disorder) of this island. Charge carriers were locally injected by the apex of an atomic force microscope tip, and the resulting two-dimensional distribution and concentration of injected charges were measured by electrical force microscopy (EFM) experiments. We show that in crystalline monolayer islands, both electrons and holes can be equally injected, at a similar charge concentration for symmetric injection bias conditions, and that both charge carriers are delocalized over the whole island. On the contrary, charges injected into a more disordered monolayer stay localized at their injection point. These different results are discussed in relation with the electrical performances of molecular devices made from these monolayers (OFET, SAMFET). These results provide insight into the electronic properties, at the nanometer scale, of these molecular devices.

On the local injection of emitted electrons into micrograins on the surface of A{sup III}–B{sup V} semiconductors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhukov, N. D., E-mail: ndzhukov@rambler.ru; Glukhovskoi, E. G.; Khazanov, A. A.

2016-06-15

The characteristics of the injection of electrons into a semiconductor from a microprobe–micrograin nanogap are investigated with a tunneling microscope in the mode of field emission into locally selected surface microcrystals of indium antimonide, indium arsenide, and gallium arsenide. The current mechanisms are established and their parameters are determined by comparing the experimental I–V characteristics and those calculated from formulas of current transport. The effect of limitation of the current into the micrograins of indium antimonide and indium arsenide which manifests itself at injection levels exceeding a certain critical value, e.g., 6 × 10{sup 16} cm{sup –3} for indium antimonidemore » and 4 × 10{sup 17} cm{sup –3} for indium arsenide, is discovered. A physical model, i.e., the localization of electrons in the surface area of a micrograin due to their Coulomb interaction, is proposed.« less

Autoradiographic localization of voltage-dependent sodium channels on the mouse neuromuscular junction using /sup 125/I-alpha scorpion toxin. I. Preferential labeling of glial cells on the presynaptic side

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boudier, J.L.; Jover, E.; Cau, P.

1988-05-01

Alpha-scorpion toxins bind specifically to the voltage-sensitive sodium channel in excitable membranes, and binding is potential-dependent. The radioiodinated toxin II from the scorpion Androctonus australis Hector (alpha ScTx) was used to localize voltage-sensitive sodium channels on the presynaptic side of mouse neuromuscular junctions (NMJ) by autoradiography using both light and electron microscopy. Silver grain localization was analyzed by the cross-fire method. At the light-microscopic level, grain density over NMJ appeared 6-8x higher than over nonjunctional muscle membrane. The specificity of labeling was verified by competition/displacement with an excess of native alpha ScTx. Labeling was also inhibited by incubation in depolarizingmore » conditions, showing its potential-dependence. At the electron-microscopic level, analysis showed that voltage-sensitive sodium channels labeled with alpha ScTx were almost exclusively localized on membranes, as expected. Due to washout after incubation, appreciable numbers of binding sites were not found on the postsynaptic membranes. However, on the presynaptic side, alpha ScTx-labeled voltage-sensitive sodium channels were localized on the membrane of non-myelin-forming Schwann cells covering NMJ. The axonal presynaptic membrane was not labeled. These results show that voltage-sensitive sodium channels are present on glial cells in vivo, as already demonstrated in vitro. It is proposed that these glial channels could be indirectly involved in the ionic homeostasis of the axonal environment.« less

Tunable Electron-Electron Interactions in LaAlO 3 / SrTiO 3 Nanostructures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheng, Guanglei; Tomczyk, Michelle; Tacla, Alexandre B.

The interface between the two complex oxides LaAlO 3 and SrTiO 3 has remarkable properties that can be locally reconfigured between conducting and insulating states using a conductive atomic force microscope. Prior investigations of “sketched” quantum dot devices revealed a phase in which electrons form pairs, implying a strongly attractive electron-electron interaction. Here, we show that these devices with strong electron-electron interactions can exhibit a gate-tunable transition from a pair-tunneling regime to a single-electron (Andreev bound state) tunneling regime where the interactions become repulsive. The electron-electron interaction sign change is associated with a Lifshitz transition where the d xz andmore » d yz bands start to become occupied. This electronically tunable electron-electron interaction, combined with the nanoscale reconfigurability of this system, provides an interesting starting point towards solid-state quantum simulation.« less

Tunable Electron-Electron Interactions in LaAlO 3 / SrTiO 3 Nanostructures

DOE PAGES

Cheng, Guanglei; Tomczyk, Michelle; Tacla, Alexandre B.; ...

2016-12-01

The interface between the two complex oxides LaAlO 3 and SrTiO 3 has remarkable properties that can be locally reconfigured between conducting and insulating states using a conductive atomic force microscope. Prior investigations of “sketched” quantum dot devices revealed a phase in which electrons form pairs, implying a strongly attractive electron-electron interaction. Here, we show that these devices with strong electron-electron interactions can exhibit a gate-tunable transition from a pair-tunneling regime to a single-electron (Andreev bound state) tunneling regime where the interactions become repulsive. The electron-electron interaction sign change is associated with a Lifshitz transition where the d xz andmore » d yz bands start to become occupied. This electronically tunable electron-electron interaction, combined with the nanoscale reconfigurability of this system, provides an interesting starting point towards solid-state quantum simulation.« less

New innovations for contrast enhancement in electron microscopy

NASA Astrophysics Data System (ADS)

Mohan, A.

In this study two techniques for producing and improving contrast in Electron Microscopy are discussed. The first technique deals with the production of secondary contrast in a Variable Pressure SEM under poor vacuum conditions using the specimen current signal. A review of the prior work in this field shows that the presence of the gas ions in the microscope column results in the amplification of the specimen current signal which is enriched in secondary content. The focus of this study is to establish practical conditions for imaging samples in the microscope using specimen current with gas amplification. This is done by understanding the different variables in the microscope which affect the image formation process and then finding out optimum conditions for obtaining the best possible image, i.e., the image most enhanced in secondary contrast. A few 'real life' samples analyzed using this technique show that the gas amplified specimen current images contain secondary information and, in some cases, provide clear advantages to imaging with conventional secondary and backscattered detectors. The second technique dealing with the production of phase contrast in the TEM for extremely thin, electron transparent samples, is analyzed. A review of the literature regarding prior work in the field shows that, while the theoretical aspects of production of phase contrast in the TEM using a phase plate are well understood, there have been problems in practically implementing this in the microscope. One major assumption with most of the studies is that a fiber, partially coated with gold, results in the formation of point charges which is an essential requirement for symmetrically shifting the phase of the electron beam. The focus of this portion of the dissertation is to image the type of fields associated with such a phase plate using the technique of electron holography. It is found that there are two types of fields associated with a phase plate of this sort. One is a cylindrical field which extends along the length of the fiber while the other is a localized spherically symmetric field. A series of simulations show that the spherical field can produce phase contrast in the TEM and also improve the contrast transfer properties of the microscope.

Orientation and phase mapping in the transmission electron microscope using precession-assisted diffraction spot recognition: state-of-the-art results.

PubMed

Viladot, D; Véron, M; Gemmi, M; Peiró, F; Portillo, J; Estradé, S; Mendoza, J; Llorca-Isern, N; Nicolopoulos, S

2013-10-01

A recently developed technique based on the transmission electron microscope, which makes use of electron beam precession together with spot diffraction pattern recognition now offers the possibility to acquire reliable orientation/phase maps with a spatial resolution down to 2 nm on a field emission gun transmission electron microscope. The technique may be described as precession-assisted crystal orientation mapping in the transmission electron microscope, precession-assisted crystal orientation mapping technique-transmission electron microscope, also known by its product name, ASTAR, and consists in scanning the precessed electron beam in nanoprobe mode over the specimen area, thus producing a collection of precession electron diffraction spot patterns, to be thereafter indexed automatically through template matching. We present a review on several application examples relative to the characterization of microstructure/microtexture of nanocrystalline metals, ceramics, nanoparticles, minerals and organics. The strengths and limitations of the technique are also discussed using several application examples. ©2013 The Authors. Journal of Microscopy published by John Wiley & Sons Ltd on behalf of Royal Microscopical Society.

Unexpected surface implanted layer in static random access memory devices observed by microwave impedance microscope

NASA Astrophysics Data System (ADS)

Kundhikanjana, W.; Yang, Y.; Tanga, Q.; Zhang, K.; Lai, K.; Ma, Y.; Kelly, M. A.; Li, X. X.; Shen, Z.-X.

2013-02-01

Real-space mapping of doping concentration in semiconductor devices is of great importance for the microelectronics industry. In this work, a scanning microwave impedance microscope (MIM) is employed to resolve the local conductivity distribution of a static random access memory sample. The MIM electronics can also be adjusted to the scanning capacitance microscopy (SCM) mode, allowing both measurements on the same region. Interestingly, while the conventional SCM images match the nominal device structure, the MIM results display certain unexpected features, which originate from a thin layer of the dopant ions penetrating through the protective layers during the heavy implantation steps.

Controlling molecular condensation/diffusion of copper phthalocyanine by local electric field induced with scanning tunneling microscope tip

NASA Astrophysics Data System (ADS)

Nagaoka, Katsumi; Yaginuma, Shin; Nakayama, Tomonobu

2018-02-01

We have discovered the condensation/diffusion phenomena of copper phthalocyanine (CuPc) molecules controlled with a pulsed electric field induced by the scanning tunneling microscope tip. This behavior is not explained by the conventional induced dipole model. In order to understand the mechanism, we have measured the electronic structure of the molecule by tunneling spectroscopy and also performed theoretical calculations on molecular orbitals. These data clearly indicate that the molecule is positively charged owing to charge transfer to the substrate, and that hydrogen bonding exists between CuPc molecules, which makes the molecular island stable.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Koenenkamp, Rolf

We report on the design, assembly, operation and application of an aberration-corrected photoemission electron microscope. The instrument used novel hyperbolic mirror-correctors with two and three electrodes that allowed simultaneous correction of spherical and chromatic aberrations. A spatial resolution of 5.4nm was obtained with this instrument in 2009, and 4.7nm in subsequent years. New imaging methodology was introduced involving interferometric imaging of light diffraction. This methodology was applied in nano-photonics and in the characterization of surface-plasmon polaritons. Photonic crystals and waveguides, optical antennas and new plasmonic devices such as routers, localizers and filters were designed and demonstrated using the new capabilitiesmore » offered by the microscope.« less

Elastic and inelastic electrons in the double-slit experiment: A variant of Feynman's which-way set-up.

PubMed

Frabboni, Stefano; Gazzadi, Gian Carlo; Grillo, Vincenzo; Pozzi, Giulio

2015-07-01

Modern nanotechnology tools allowed us to prepare slits of 90 nm width and 450 nm spacing in a screen almost completely opaque to 200 keV electrons. Then by covering both slits with a layer of amorphous material and carrying out the experiment in a conventional transmission electron microscope equipped with an energy filter we can demonstrate that the diffraction pattern, taken by selecting the elastically scattered electrons, shows the presence of interference fringes, but with a bimodal envelope which can be accounted for by taking into account the non-constant thickness of the deposited layer. However, the intensity of the inelastically scattered electrons in the diffraction plane is very broad and at the limit of detectability. Therefore the experiment was repeated using an aluminum film and a microscope also equipped with a Schottky field emission gun. It was thus possible to observe also the image due to the inelastically scattered electron, which does not show interference phenomena both in the Fraunhofer or Fresnel regimes. If we assume that inelastic scattering through the thin layer covering the slits provides the dissipative process of interaction responsible for the localization mechanism, then these experiments can be considered a variant of the Feynman which-way thought experiment. Copyright © 2015 Elsevier B.V. All rights reserved.

Analysis of Local Structure, Chemistry and Bonding by Electron Energy Loss Spectroscopy

NASA Astrophysics Data System (ADS)

Mayer, Joachim

In the present chapter, the reader will first be introduced briefly to the basic principles of analytical transmission electron microscopy (ATEM) with special emphasis on electron energy-loss spectroscopy (EELS) and energy-filtering TEM. The quantification of spectra to obtain chemical information and the origin and interpretation of near-edge fine structures in EELS (ELNES) are discussed. Special attention will be given to the characterization of internal interfaces and the literature in this area will be reviewed. Selected examples of the application of ATEM in the investigation of internal interfaces will be given. These examples include both EELS in the energy-filtering TEM and in the scanning transmission electron microscope (STEM).

SQCRAMscope imaging of transport in an iron-pnictide superconductor

NASA Astrophysics Data System (ADS)

Yang, Fan; Kollar, Alicia; Taylor, Stephen; Palmstrom, Johanna; Chu, Jiun-Haw; Fisher, Ian; Lev, Benjamin

2017-04-01

Microscopic imaging of local magnetic fields provides a window into the organizing principles of complex and technologically relevant condensed matter materials. However, a wide variety of intriguing strongly correlated and topologically nontrivial materials exhibit poorly understood phenomena outside the detection capability of state-of-the-art high-sensitivity, high-resolution scanning probe magnetometers. We have recently introduced a quantum-noise-limited scanning probe magnetometer that can operate from room-to-cryogenic temperatures with unprecedented DC-field sensitivity and micron-scale resolution. The Scanning Quantum Cryogenic Atom Microscope (SQCRAMscope) employs a magnetically levitated atomic Bose-Einstein condensate (BEC), thereby providing immunity to conductive and blackbody radiative heating. We will report on the first use of the SQCRAMscope for imaging a strongly correlated material. Specifically, we will present measurements of electron transport in iron-pnictide superconductors across the electron nematic phase transition at T = 135 K.

Is localized infrared spectroscopy now possible in the electron microscope?

PubMed

Rez, Peter

2014-06-01

The recently developed in-column monochromators make it possible to record energy-c spectra with resolutions better than 30 meV from nanometer-sized regions. It should therefore in principle be possible to detect localized vibrational excitations. The scattering geometry in the electron microscope means that bond stretching in the specimen plane or longitudinal optic phonons dominate the scattering. Most promising for initial studies are vibrations with energies between 300 and 400 meV from hydrogen bonded to other atoms. Estimates of the scattering cross-sections on the basis of a simple model show that they are about the same as inner shell scattering cross-sections. Cross-sections also increase with charge transfer between the atoms, and theory incorporating realistic charge distributions shows that signal/noise is the only limitation to high-resolution imaging. Given the magnitude of the scattering cross-sections, minimizing the tail of the zero-loss peak is just as important as achieving a small-width at half-maximum. Improvements in both resolution and controlling the zero-loss tail will be necessary before it is practical to detect optic phonons in solids between 40 and 60 meV.

High cycle fatigue in the transmission electron microscope

DOE PAGES

Bufford, Daniel C.; Stauffer, Douglas; Mook, William M.; ...

2016-06-28

One of the most common causes of structural failure in metals is fatigue induced by cyclic loading. Historically, microstructure-level analysis of fatigue cracks has primarily been performed post mortem. However, such investigations do not directly reveal the internal structural processes at work near micro- and nanoscale fatigue cracks and thus do not provide direct evidence of active microstructural mechanisms. In this paper, the tension–tension fatigue behavior of nanocrystalline Cu was monitored in real time at the nanoscale by utilizing a new capability for quantitative cyclic mechanical loading performed in situ in a transmission electron microscope (TEM). Controllable loads were appliedmore » at frequencies from one to several hundred hertz, enabling accumulations of 10 6 cycles within 1 h. The nanometer-scale spatial resolution of the TEM allows quantitative fatigue crack growth studies at very slow crack growth rates, measured here at ~10 –12 m·cycle –1. This represents an incipient threshold regime that is well below the tensile yield stress and near the minimum conditions for fatigue crack growth. Evidence of localized deformation and grain growth within 150 nm of the crack tip was observed by both standard imaging and precession electron diffraction orientation mapping. Finally, these observations begin to reveal with unprecedented detail the local microstructural processes that govern damage accumulation, crack nucleation, and crack propagation during fatigue loading in nanocrystalline Cu.« less

High cycle fatigue in the transmission electron microscope

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bufford, Daniel C.; Stauffer, Douglas; Mook, William M.

One of the most common causes of structural failure in metals is fatigue induced by cyclic loading. Historically, microstructure-level analysis of fatigue cracks has primarily been performed post mortem. However, such investigations do not directly reveal the internal structural processes at work near micro- and nanoscale fatigue cracks and thus do not provide direct evidence of active microstructural mechanisms. In this paper, the tension–tension fatigue behavior of nanocrystalline Cu was monitored in real time at the nanoscale by utilizing a new capability for quantitative cyclic mechanical loading performed in situ in a transmission electron microscope (TEM). Controllable loads were appliedmore » at frequencies from one to several hundred hertz, enabling accumulations of 10 6 cycles within 1 h. The nanometer-scale spatial resolution of the TEM allows quantitative fatigue crack growth studies at very slow crack growth rates, measured here at ~10 –12 m·cycle –1. This represents an incipient threshold regime that is well below the tensile yield stress and near the minimum conditions for fatigue crack growth. Evidence of localized deformation and grain growth within 150 nm of the crack tip was observed by both standard imaging and precession electron diffraction orientation mapping. Finally, these observations begin to reveal with unprecedented detail the local microstructural processes that govern damage accumulation, crack nucleation, and crack propagation during fatigue loading in nanocrystalline Cu.« less

High-resolution, high-throughput imaging with a multibeam scanning electron microscope.

PubMed

Eberle, A L; Mikula, S; Schalek, R; Lichtman, J; Knothe Tate, M L; Zeidler, D

2015-08-01

Electron-electron interactions and detector bandwidth limit the maximal imaging speed of single-beam scanning electron microscopes. We use multiple electron beams in a single column and detect secondary electrons in parallel to increase the imaging speed by close to two orders of magnitude and demonstrate imaging for a variety of samples ranging from biological brain tissue to semiconductor wafers. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

Golgi, electron-microscopic and combined Golgi-electron-microscopic studies of the mitral cells in the goldfish olfactory bulb.

PubMed

Oka, Y

1983-04-01

The local neuronal circuitry of goldfish olfactory bulb was analyzed in Golgi preparations combining light- and electron-microscopy, as well as in routinely prepared ultrastructural preparations. Mitral cells were identified with the light-microscope in Golgi-impregnated thick sections according to the following criteria: (1) cell bodies were distributed irregularly in a wide layer between 100 and 200 micrometer from the surface, (2) cell bodies were larger than other neurons (10-20 micrometer in diameter), and (3) the dendrites were directed toward the superficially-located olfactory nerve layer where they ended as highly branched glomerular tufts. These impregnated cells were examined by electron-microscopy in serial section. The results demonstrate synaptic organization in relation to the mitral cells. (1) Glomerular tufts received afferent input from primary olfactory axons which made Gray's Type I synaptic contacts. These dendrites also had reciprocal dendrodendritic synapses with dendrites of certain non-mitral cells. (2) Dendritic shafts of mitral cells made reciprocal dendritic synapses with dendrites of certain non-mitral cells. (3) Cell bodies and their initial axon segments had reciprocal synapses with certain dendrites but occurred infrequently. In reciprocal synapses, the direction of the Gray Type I (asymmetrical) is away from the mitral cell while those with Gray Type II synapses (symmetrical) are toward the mitral cell. Assuming that the type I synapse is excitatory and Type II is inhibitory, these findings explain the electrophysiological demonstration of self-inhibition discharge found in mitral cells.

An effective fixative for glucocorticoid receptors in fetal tissues

DOE Office of Scientific and Technical Information (OSTI.GOV)

Koga, T.; Kurisu, K.

1982-01-01

As a preliminary study in an autoradiographic study of glucocorticoid (GC) receptor localization in orofacial tissues of mouse fetuses, a search was made to determine the most effective fixative for preservation of the GC-receptor complex. Twelve-day-old mouse fetuses were administered tritiated triamcinolone acetonide (/sup 3/H-TAC) intraamniotically and subsequently processed by one of the following three procedures: freeze-drying, prefixation with Karnovsky's fixative, or the catechin fixative (Karnovsky's fixative containing 1% D-catechin) and postfixation with osmium tetroxide. Light microscopic autoradiography and liquid scintillation counting of the specimens revealed that the catechin fixative gave the best results for fixation of the steroid-receptor complexmore » and preservation of tissue structure. Light and electron microscopic autoradiographic studies of the time course of the localization of /sup 3/H-TAC in palatal shelves supported the catechin fixative as being the most effective in preservation of GC-receptor or ligand complexes.« less

Modeling secondary electron emission from nanostructured materials in helium ion microscope

NASA Astrophysics Data System (ADS)

Ohya, K.; Yamanaka, T.

2013-11-01

Charging of a SiO2 layer on a Si substrate during helium (He) beam irradiation is investigated at an energy range relevant to a He ion microscope (HIM). A self-consistent calculation is performed to model the transport of the ions and secondary electrons (SEs), the charge accumulation in the layer, and the electric field below and above the surface. The calculated results are compared with those for gallium (Ga) ions at the same energy and 1 keV electrons corresponding to a low-voltage scanning electron microscope (SEM). The charging of thin layers (<250 nm) is strongly suppressed due to wide depth and lateral distributions of the He ions in the layer, the voltage of which is much lower than that for the Ga ions and the electrons, where the distributions are much more localized. When the irradiation approaches the edge of a 100-nm-high SiO2 step formed on a Si substrate, a sharp increase in the number of SEs is observed, irrespective of whether a material is charged or not. When the He ions are incident on the bottom of the step, the re-entrance of SEs emitted from the substrate into the sidewall is clearly observed, but it causes the sidewall to be charged negatively. At the positions on the SiO2 layer away from the step edge, the charging voltage becomes positive with increasing number of Ga ions and electrons. However, He ions do not induce such a voltage due to strong relaxation of positive and negative charges in the Si substrate and their recombination in the SiO2 layer.

Imaging of current density distributions with a Nb weak-link scanning nano-SQUID microscope

PubMed Central

Shibata, Yusuke; Nomura, Shintaro; Kashiwaya, Hiromi; Kashiwaya, Satoshi; Ishiguro, Ryosuke; Takayanagi, Hideaki

2015-01-01

Superconducting quantum interference devices (SQUIDs) are accepted as one of the highest magnetic field sensitive probes. There are increasing demands to image local magnetic fields to explore spin properties and current density distributions in a two-dimensional layer of semiconductors or superconductors. Nano-SQUIDs have recently attracting much interest for high spatial resolution measurements in nanometer-scale samples. Whereas weak-link Dayem Josephson junction nano-SQUIDs are suitable to miniaturization, hysteresis in current-voltage (I-V) characteristics that is often observed in Dayem Josephson junction is not desirable for a scanning microscope. Here we report on our development of a weak-link nano-SQUIDs scanning microscope with small hysteresis in I-V curve and on reconstructions of two-dimensional current density vector in two-dimensional electron gas from measured magnetic field. PMID:26459874

Imaging of current density distributions with a Nb weak-link scanning nano-SQUID microscope

NASA Astrophysics Data System (ADS)

Shibata, Yusuke; Nomura, Shintaro; Kashiwaya, Hiromi; Kashiwaya, Satoshi; Ishiguro, Ryosuke; Takayanagi, Hideaki

2015-10-01

Superconducting quantum interference devices (SQUIDs) are accepted as one of the highest magnetic field sensitive probes. There are increasing demands to image local magnetic fields to explore spin properties and current density distributions in a two-dimensional layer of semiconductors or superconductors. Nano-SQUIDs have recently attracting much interest for high spatial resolution measurements in nanometer-scale samples. Whereas weak-link Dayem Josephson junction nano-SQUIDs are suitable to miniaturization, hysteresis in current-voltage (I-V) characteristics that is often observed in Dayem Josephson junction is not desirable for a scanning microscope. Here we report on our development of a weak-link nano-SQUIDs scanning microscope with small hysteresis in I-V curve and on reconstructions of two-dimensional current density vector in two-dimensional electron gas from measured magnetic field.

Designs for a quantum electron microscope.

PubMed

Kruit, P; Hobbs, R G; Kim, C-S; Yang, Y; Manfrinato, V R; Hammer, J; Thomas, S; Weber, P; Klopfer, B; Kohstall, C; Juffmann, T; Kasevich, M A; Hommelhoff, P; Berggren, K K

2016-05-01

One of the astounding consequences of quantum mechanics is that it allows the detection of a target using an incident probe, with only a low probability of interaction of the probe and the target. This 'quantum weirdness' could be applied in the field of electron microscopy to generate images of beam-sensitive specimens with substantially reduced damage to the specimen. A reduction of beam-induced damage to specimens is especially of great importance if it can enable imaging of biological specimens with atomic resolution. Following a recent suggestion that interaction-free measurements are possible with electrons, we now analyze the difficulties of actually building an atomic resolution interaction-free electron microscope, or "quantum electron microscope". A quantum electron microscope would require a number of unique components not found in conventional transmission electron microscopes. These components include a coherent electron beam-splitter or two-state-coupler, and a resonator structure to allow each electron to interrogate the specimen multiple times, thus supporting high success probabilities for interaction-free detection of the specimen. Different system designs are presented here, which are based on four different choices of two-state-couplers: a thin crystal, a grating mirror, a standing light wave and an electro-dynamical pseudopotential. Challenges for the detailed electron optical design are identified as future directions for development. While it is concluded that it should be possible to build an atomic resolution quantum electron microscope, we have also identified a number of hurdles to the development of such a microscope and further theoretical investigations that will be required to enable a complete interpretation of the images produced by such a microscope. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Effects of low-energy electron irradiation on formation of nitrogen–vacancy centers in single-crystal diamond

DOE PAGES

Schwartz, J.; Aloni, S.; Ogletree, D. F.; ...

2012-04-20

Exposure to beams of low-energy electrons (2-30 keV) in a scanning electron microscope locally induces formation of NV-centers without thermal annealing in diamonds that have been implanted with nitrogen ions. In this study, we find that non-thermal, electron-beam-induced NV-formation is about four times less efficient than thermal annealing. But NV-center formation in a consecutive thermal annealing step (800°C) following exposure to low-energy electrons increases by a factor of up to 1.8 compared to thermal annealing alone. Finally, these observations point to reconstruction of nitrogen-vacancy complexes induced by electronic excitations from low-energy electrons as an NV-center formation mechanism and identify localmore » electronic excitations as a means for spatially controlled room-temperature NV-center formation.« less

Microscopic theory for coupled atomistic magnetization and lattice dynamics

NASA Astrophysics Data System (ADS)

Fransson, J.; Thonig, D.; Bessarab, P. F.; Bhattacharjee, S.; Hellsvik, J.; Nordström, L.

2017-12-01

A coupled atomistic spin and lattice dynamics approach is developed which merges the dynamics of these two degrees of freedom into a single set of coupled equations of motion. The underlying microscopic model comprises local exchange interactions between the electron spin and magnetic moment and the local couplings between the electronic charge and lattice displacements. An effective action for the spin and lattice variables is constructed in which the interactions among the spin and lattice components are determined by the underlying electronic structure. In this way, expressions are obtained for the electronically mediated couplings between the spin and lattice degrees of freedom, besides the well known interatomic force constants and spin-spin interactions. These former susceptibilities provide an atomistic ab initio description for the coupled spin and lattice dynamics. It is important to notice that this theory is strictly bilinear in the spin and lattice variables and provides a minimal model for the coupled dynamics of these subsystems and that the two subsystems are treated on the same footing. Questions concerning time-reversal and inversion symmetry are rigorously addressed and it is shown how these aspects are absorbed in the tensor structure of the interaction fields. By means of these results regarding the spin-lattice coupling, simple explanations of ionic dimerization in double-antiferromagnetic materials, as well as charge density waves induced by a nonuniform spin structure, are given. In the final parts, coupled equations of motion for the combined spin and lattice dynamics are constructed, which subsequently can be reduced to a form which is analogous to the Landau-Lifshitz-Gilbert equations for spin dynamics and a damped driven mechanical oscillator for the ionic motion. It is important to notice, however, that these equations comprise contributions that couple these descriptions into one unified formulation. Finally, Kubo-like expressions for the discussed exchanges in terms of integrals over the electronic structure and, moreover, analogous expressions for the damping within and between the subsystems are provided. The proposed formalism and types of couplings enable a step forward in the microscopic first principles modeling of coupled spin and lattice quantities in a consistent format.

Microscale localization and isolation of light emitting imperfections in monocrystalline silicon solar cells

NASA Astrophysics Data System (ADS)

Gajdoš, Adam; Škvarenina, Lubomír.; Škarvada, Pavel; Macků, Robert

2017-12-01

An imperfections or defects may appear in fabricated monocrystalline solar cells. These microstructural imperfections could have impact on the parameters of whole solar cell. The research is divided into two parts, firstly, the detection and localization defects by using several techniques including current-voltage measurement, scanning probe microscopy (SPM), scanning electron microscope (SEM) and electroluminescence. Secondly, the defects isolation by a focused ion beam (FIB) milling and impact of a milling process on solar cells. The defect detection is realized by I-V measurement under reverse biased sample. For purpose of localization, advantage of the fact that defects or imperfections in silicon solar cells emit the visible and near infrared electroluminescence under reverse biased voltage is taken, and CCD camera measurement for macroscopic localization of these spots is applied. After rough macroscopic localization, microscopic localization by scanning probe microscopy combined with a photomultiplier (shadow mapping) is performed. Defect isolation is performed by a SEM equipped with the FIB instrument. FIB uses a beam of gallium ions which modifies crystal structure of a material and may affect parameters of solar cell. As a result, it is interesting that current in reverse biased sample with isolated defect is smaller approximately by 2 orders than current before isolation process.

Two new Neotropical species of Ceracis Mellié (Coleoptera, Ciidae) and redefinition of the cucullatus group

PubMed Central

Antunes-Carvalho, Caio; Lopes-Andrade, Cristiano

2011-01-01

Abstract Two new Neotropical species of Ceracis Mellié are described: Ceracis cassumbensis Antunes-Carvalho & Lopes-Andrade, sp. n. from a single locality in northeastern Brazil and Ceracis navarretei Antunes-Carvalho & Lopes-Andrade, sp. n. from a single locality in southern Mexico. Scanning Electron Microscope images of adults and photographs of holotypes and male terminalia are provided for both species, their similarities and differences with other Ceracis are briefly discussed, and the cucullatus species-group is redefined for including the new species described herein. PMID:22140333

Probing the symmetry of the potential of localized surface plasmon resonances with phase-shaped electron beams.

PubMed

Guzzinati, Giulio; Béché, Armand; Lourenço-Martins, Hugo; Martin, Jérôme; Kociak, Mathieu; Verbeeck, Jo

2017-04-12

Plasmonics, the science and technology of the interaction of light with metallic objects, is fundamentally changing the way we can detect, generate and manipulate light. Although the field is progressing swiftly, thanks to the availability of nanoscale manufacturing and analysis methods, fundamental properties such as the plasmonic excitations' symmetries cannot be accessed directly, leading to a partial, sometimes incorrect, understanding of their properties. Here we overcome this limitation by deliberately shaping the wave function of an electron beam to match a plasmonic excitations' symmetry in a modified transmission electron microscope. We show experimentally and theoretically that this offers selective detection of specific plasmon modes within metallic nanoparticles, while excluding modes with other symmetries. This method resembles the widespread use of polarized light for the selective excitation of plasmon modes with the advantage of locally probing the response of individual plasmonic objects and a far wider range of symmetry selection criteria.

75 FR 13486 - Application(s) for Duty-Free Entry of Scientific Instruments

Federal Register 2010, 2011, 2012, 2013, 2014

2010-03-22

... University, One Waterfront Place, PO Box 6024, Morgantown, WV 26506. Instrument: Electron Microscope.... Justification for Duty-Free Entry: There are no domestic manufacturers of this type of electron microscope.... Lawrence University, 23 Romoda Drive, Canton, NY 13617. Instrument: Electron Microscope. Manufacturer: FEI...

Ultrastructural localization of acetylcholinesterase in neurofibrillary tangles, neuropil threads and senile plaques in aged and Alzheimer's brain.

PubMed

Gomez-Ramos, P; Mufson, E J; Moran, M A

1992-01-13

Acetylcholinesterase (AChE) histochemistry was used to evaluate the accumulation of this enzyme in senile plaques, neurofibrillary tangles and neuropil threads using light and electron microscopy in Alzheimer's disease as well as non-demented aged brains. Under the electron microscope, a crystalline-like AChE precipitate was localized over paired helical filaments and straight filaments in both neurofibrillary tangles and neuropil threads. AChE reaction product also decorated the amyloid fibrils in diffuse plaques as well as the halo and the heavy accumulation of amyloid which forms the core of classical plaques. In both diffuse plaques and the halo of classical plaques, we found AChE-positive structures resembling cell processes, which in some cases appeared to contain amyloid fibrils. The possible origin and significance of AChE localized over paired helical filaments, straight filaments and amyloid is discussed.

Controlling the Local Electronic Properties of Si(553)-Au through Hydrogen Doping

NASA Astrophysics Data System (ADS)

Hogan, C.; Speiser, E.; Chandola, S.; Suchkova, S.; Aulbach, J.; Schäfer, J.; Meyer, S.; Claessen, R.; Esser, N.

2018-04-01

We propose a quantitative and reversible method for tuning the charge localization of Au-stabilized stepped Si surfaces by site-specific hydrogenation. This is demonstrated for Si(553)-Au as a model system by combining density functional theory simulations and reflectance anisotropy spectroscopy experiments. We find that controlled H passivation is a two-step process: step-edge adsorption drives excess charge into the conducting metal chain "reservoir" and renders it insulating, while surplus H recovers metallic behavior. Our approach illustrates a route towards microscopic manipulation of the local surface charge distribution and establishes a reversible switch of site-specific chemical reactivity and magnetic properties on vicinal surfaces.

77 FR 20009 - Howard Hughes Medical Institute, et al.; Notice of Consolidated Decision on Applications for Duty...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-04-03

... decision consolidated pursuant to Section 6(c) of the Educational, Scientific, and Cultural Materials... 07470. Instrument: Electron Microscope. Manufacturer: Hitachi High Technologies America, Inc., Japan... educational uses requiring an electron microscope. We know of no electron microscope, or any other instrument...

The Design and Construction of a Simple Transmission Electron Microscope for Educational Purposes.

ERIC Educational Resources Information Center

Hearsey, Paul K.

This document presents a model for a simple transmission electron microscope for educational purposes. This microscope could demonstrate thermonic emission, particle acceleration, electron deflection, and flourescence. It is designed to be used in high school science courses, particularly physics, taking into account the size, weight, complexity…

75 FR 20982 - West Virginia University, et al., Notice of Consolidated Decision on Applications for Duty-Free...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-04-22

... of Consolidated Decision on Applications for Duty-Free Entry of Electron Microscopes This is a..., Morgantown, WV 26506. Instrument: Electron Microscope. Manufacturer: JEOL, Japan. Intended Use: See notice at... Agency, Cincinnati, OH 45268. Instrument: Electron Microscope. Manufacturer: JEOL, Japan. Intended Use...

76 FR 17381 - Battelle Memorial Institute, et al.; Notice of Consolidated Decision on Applications for Duty...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-03-29

....; Notice of Consolidated Decision on Applications for Duty-Free Entry of Electron Microscopes This is a..., Richland, WA 99354. Instrument: Electron Microscope. Manufacturer: FEI Company, the Netherlands. Intended... Rico, San Juan, PR 00936-5067. Instrument: Electron Microscope. Manufacturer: JEOL, Ltd., Japan...

75 FR 32901 - Colorado State University, et al.; Notice of Consolidated Decision on Applications for Duty-Free...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-06-10

....; Notice of Consolidated Decision on Applications for Duty-Free Entry of Electron Microscopes This is a... Collins, CO 80523. Instrument: Electron Microscope. Manufacturer: JEOL Ltd., Japan. Intended Use: See... 97401-3753. Instrument: Electron Microscope. Manufacturer: FEI Company, Czech Republic. Intended Use...

76 FR 58245 - Ohio State University, et al.; Notice of Consolidated Decision on Applications for Duty-Free...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-09-20

... Consolidated Decision on Applications for Duty-Free Entry of Electron Microscope This is a decision... 43210. Instrument: Electron Microscope. Manufacturer: FEI Company, Czech Republic. Intended Use: See..., San Antonio, TX 78239-5166. Instrument: Electron Microscope. Manufacturer: FEI Company, Czech Republic...

78 FR 20296 - Purdue University et al.; Notice of Consolidated Decision on Applications for Duty-Free Entry of...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-04-04

... Consolidated Decision on Applications for Duty-Free Entry of Electron Microscope This is a decision... 37235. Instrument: Electron Microscope. Manufacturer: FEI Company, the Netherlands. Intended Use: See... Lafayette, IN 47907-2024. Instrument: Electron Microscope. Manufacturer: FEI Company, the Netherlands...

76 FR 68717 - University of Arkansas, et al.; Notice of Consolidated Decision on Applications for Duty-Free...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-11-07

... of Consolidated Decision on Applications for Duty-Free Entry of Electron Microscope This is a... Business Affairs, Fayetteville, AR 72701-1201. Instrument: Electron Microscope. Manufacturer: JEOL Ltd...: Brookhaven National Laboratory, Upton, NY 11973. Instrument: Electron Microscope. Manufacturer: JEOL, Ltd...

Secondary electron imaging of monolayer materials inside a transmission electron microscope

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cretu, Ovidiu, E-mail: cretu.ovidiu@nims.go.jp; Lin, Yung-Chang; Suenaga, Kazutomo

2015-08-10

A scanning transmission electron microscope equipped with a backscattered and secondary electron detector is shown capable to image graphene and hexagonal boron nitride monolayers. Secondary electron contrasts of the two lightest monolayer materials are clearly distinguished from the vacuum level. A signal difference between these two materials is attributed to electronic structure differences, which will influence the escape probabilities of the secondary electrons. Our results show that the secondary electron signal can be used to distinguish between the electronic structures of materials with atomic layer sensitivity, enhancing its applicability as a complementary signal in the analytical microscope.

Integration of a high-NA light microscope in a scanning electron microscope.

PubMed

Zonnevylle, A C; Van Tol, R F C; Liv, N; Narvaez, A C; Effting, A P J; Kruit, P; Hoogenboom, J P

2013-10-01

We present an integrated light-electron microscope in which an inverted high-NA objective lens is positioned inside a scanning electron microscope (SEM). The SEM objective lens and the light objective lens have a common axis and focal plane, allowing high-resolution optical microscopy and scanning electron microscopy on the same area of a sample simultaneously. Components for light illumination and detection can be mounted outside the vacuum, enabling flexibility in the construction of the light microscope. The light objective lens can be positioned underneath the SEM objective lens during operation for sub-10 μm alignment of the fields of view of the light and electron microscopes. We demonstrate in situ epifluorescence microscopy in the SEM with a numerical aperture of 1.4 using vacuum-compatible immersion oil. For a 40-nm-diameter fluorescent polymer nanoparticle, an intensity profile with a FWHM of 380 nm is measured whereas the SEM performance is uncompromised. The integrated instrument may offer new possibilities for correlative light and electron microscopy in the life sciences as well as in physics and chemistry. © 2013 The Authors Journal of Microscopy © 2013 Royal Microscopical Society.

Atmospheric scanning electron microscope observes cells and tissues in open medium through silicon nitride film.

PubMed

Nishiyama, Hidetoshi; Suga, Mitsuo; Ogura, Toshihiko; Maruyama, Yuusuke; Koizumi, Mitsuru; Mio, Kazuhiro; Kitamura, Shinichi; Sato, Chikara

2010-03-01

Direct observation of subcellular structures and their characterization is essential for understanding their physiological functions. To observe them in open environment, we have developed an inverted scanning electron microscope with a detachable, open-culture dish, capable of 8 nm resolution, and combined with a fluorescence microscope quasi-simultaneously observing the same area from the top. For scanning electron microscopy from the bottom, a silicon nitride film window in the base of the dish maintains a vacuum between electron gun and open sample dish while allowing electrons to pass through. Electrons are backscattered from the sample and captured by a detector under the dish. Cells cultured on the open dish can be externally manipulated under optical microscopy, fixed, and observed using scanning electron microscopy. Once fine structures have been revealed by scanning electron microscopy, their component proteins may be identified by comparison with separately prepared fluorescence-labeled optical microscopic images of the candidate proteins, with their heavy-metal-labeled or stained ASEM images. Furthermore, cell nuclei in a tissue block stained with platinum-blue were successfully observed without thin-sectioning, which suggests the applicability of this inverted scanning electron microscope to cancer diagnosis. This microscope visualizes mesoscopic-scale structures, and is also applicable to non-bioscience fields including polymer chemistry. (c) 2010 Elsevier Inc. All rights reserved.

Correction of image drift and distortion in a scanning electron microscopy.

PubMed

Jin, P; Li, X

2015-12-01

Continuous research on small-scale mechanical structures and systems has attracted strong demand for ultrafine deformation and strain measurements. Conventional optical microscope cannot meet such requirements owing to its lower spatial resolution. Therefore, high-resolution scanning electron microscope has become the preferred system for high spatial resolution imaging and measurements. However, scanning electron microscope usually is contaminated by distortion and drift aberrations which cause serious errors to precise imaging and measurements of tiny structures. This paper develops a new method to correct drift and distortion aberrations of scanning electron microscope images, and evaluates the effect of correction by comparing corrected images with scanning electron microscope image of a standard sample. The drift correction is based on the interpolation scheme, where a series of images are captured at one location of the sample and perform image correlation between the first image and the consequent images to interpolate the drift-time relationship of scanning electron microscope images. The distortion correction employs the axial symmetry model of charged particle imaging theory to two images sharing with the same location of one object under different imaging fields of view. The difference apart from rigid displacement between the mentioned two images will give distortion parameters. Three-order precision is considered in the model and experiment shows that one pixel maximum correction is obtained for the employed high-resolution electron microscopic system. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

Tunneling-Electron-Induced Light Emission from Single Gold Nanoclusters.

PubMed

Yu, Arthur; Li, Shaowei; Czap, Gregory; Ho, W

2016-09-14

The coupling of tunneling electrons with the tip-nanocluster-substrate junction plasmon was investigated by monitoring light emission in a scanning tunneling microscope (STM). Gold atoms were evaporated onto the ∼5 Å thick Al2O3 thin film grown on the NiAl (110) surface where they formed nanoclusters 3-7 nm wide. Scanning tunneling spectroscopy (STS) of these nanoclusters revealed quantum-confined electronic states. Spatially resolved photon imaging showed localized emission hot spots. Size dependent study and light emission from nanocluster dimers further support the viewpoint that coupling of tunneling electrons to the junction plasmon is the main radiative mechanism. These results showed the potential of the STM to reveal the electronic and optical properties of nanoscale metallic systems in the confined geometry of the tunnel junction.

[Thirty years of the electron microscope investigation in zoology and parasitology in the Zoological Institute of the Russian Academy of Sciences].

PubMed

Shatrov, A B

2003-01-01

The history of the electron microscope investigations in zoology and parasitology in the Zoological Institute of the Russian Academy of Sciences and progress in scanning and transmission electron microscope investigations in this field of biology to the moment are briefly accounted.

75 FR 52928 - Emory University, et al., Notice of Consolidated Decision on Applications for Duty-Free Entry of...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-08-30

... Consolidated Decision on Applications for Duty-Free Entry of Electron Microscopes This is a decision... 30322. Instrument: Electron Microscope. Manufacturer: JEOL, Ltd., Japan. Intended Use: See notice at 75... Department of Health, Menands, NY 12204-2719. Instrument: Electron Microscope. Manufacturer: JEOL Ltd., Japan...

Imaging of Norway spruce early somatic embryos with the ESEM, Cryo-SEM and laser scanning microscope.

PubMed

Neděla, Vilém; Hřib, Jiří; Havel, Ladislav; Hudec, Jiří; Runštuk, Jiří

2016-05-01

This article describes the surface structure of Norway spruce early somatic embryos (ESEs) as a typical culture with asynchronous development. The microstructure of extracellular matrix covering ESEs were observed using the environmental scanning electron microscope as a primary tool and using the scanning electron microscope with cryo attachment and laser electron microscope as a complementary tool allowing our results to be proven independently. The fresh samples were observed in conditions of the air environment of the environmental scanning electron microscope (ESEM) with the pressure from 550Pa to 690Pa and the low temperature of the sample from -18°C to -22°C. The samples were studied using two different types of detector to allow studying either the thin surface structure or material composition. The scanning electron microscope with cryo attachment was used for imaging frozen extracellular matrix microstructure with higher resolution. The combination of both electron microscopy methods was suitable for observation of "native" plant samples, allowing correct evaluation of our results, free of error and artifacts. Copyright © 2016 Elsevier Ltd. All rights reserved.

Nanofabrication with a helium ion microscope

NASA Astrophysics Data System (ADS)

Maas, Diederik; van Veldhoven, Emile; Chen, Ping; Sidorkin, Vadim; Salemink, Huub; van der Drift, Emile..; Alkemade, Paul

2010-03-01

The recently introduced helium ion microscope (HIM) is capable of imaging and fabrication of nanostructures thanks to its sub-nanometer sized ion probe. The unique interaction of the helium ions with the sample material provides very localized secondary electron emission, thus providing a valuable signal for high-resolution imaging as well as a mechanism for very precise nanofabrication. The low proximity effects, due to the low yield of backscattered ions and the confinement of the forward scattered ions into a narrow cone, enable patterning of ultra-dense sub-10 nm structures. This paper presents various nanofabrication results obtained with direct-write, with scanning helium ion beam lithography, and with helium ion beam induced deposition.

Electronic Interfacial Effects in Epitaxial Heterostructures based on LaMnO3.

NASA Astrophysics Data System (ADS)

Christen, Hans M.; Varela, M.; Lee, H. N.; Kim, D. H.; Chisholm, M. F.; Cantoni, C.; Petit, L.; Schulthess, T. C.; Lowndes, D. H.

2006-03-01

Studies of chemically abrupt interfaces provide an ideal platform to study the effects of discontinuities and asymmetries of the electronic configuration on the transport and magnetic properties of complex oxides. In addition, the behavior of complex materials near interfaces plays the most crucial role not only in devices and nanostructures but also in complex structures in the form of composites and superlattices, including artificial multiferroics. Interfaces in the ABO3 perovskite system are particularly attractive because structurally similar oxides with fundamentally different physical properties can be integrated epitaxially. To explore the electronic effects at interfaces and to probe the physical properties that result from local electronic changes, we have synthesized structures containing LaMnO3 and insulating perovskites using pulsed laser deposition. The local electron energy loss spectroscopy (EELS) capability of a scanning transmission electron microscope (STEM) is used to probe the electronic configuration in the LaMnO3 films as a function of the distance from the interfaces. The results are compared to macroscopic measurements and theoretical predictions. Research sponsored by the U.S. Department of Energy under contract DE-AC05-00OR22725 with the Oak Ridge National Laboratory, managed by UT-Battelle, LLC.

Investigation of local modification and luminescence of a carbon nanotube by scanning tunneling microscopy

NASA Astrophysics Data System (ADS)

Katano, Satoshi; Fujita, Hiroto; Uehara, Yoichi

2018-01-01

We have studied the nanoscale luminescence from a multiwalled carbon nanotube (CNT) adsorbed on Au(111) using a scanning tunneling microscope (STM). STM images revealed that a number of isolated chains of CNTs can be deposited by dry contact transfer while keeping the surface clean. By injecting tunneling electrons from the STM tip to the CNT, we observed STM light emission (STM-LE) from the CNT in the visible-light range, showing electronic transitions between the bands associated with the van Hove singularity in the density of states of the CNT. The STM-LE spectrum was obviously changed after introducing the local defect created by the STM tip, indicating the controllability of the nanoscale luminescence within a single chain of a CNT.

Dynamics and reactivity of trapped electrons on supported ice crystallites.

PubMed

Stähler, Julia; Gahl, Cornelius; Wolf, Martin

2012-01-17

The solvation dynamics and reactivity of localized excess electrons in aqueous environments have attracted great attention in many areas of physics, chemistry, and biology. This manifold attraction results from the importance of water as a solvent in nature as well as from the key role of low-energy electrons in many chemical reactions. One prominent example is the electron-induced dissociation of chlorofluorocarbons (CFCs). Low-energy electrons are also critical in the radiation chemistry that occurs in nuclear reactors. Excess electrons in an aqueous environment are localized and stabilized by the local rearrangement of the surrounding water dipoles. Such solvated or hydrated electrons are known to play an important role in systems such as biochemical reactions and atmospheric chemistry. Despite numerous studies over many years, little is known about the microscopic details of these electron-induced chemical processes, and interest in the fundamental processes involved in the reactivity of trapped electrons continues. In this Account, we present a surface science study of the dynamics and reactivity of such localized low-energy electrons at D(2)O crystallites that are supported by a Ru(001) single crystal metal surface. This approach enables us to investigate the generation and relaxation dynamics as well as dissociative electron attachment (DEA) reaction of excess electrons under well-defined conditions. They are generated by photoexcitation in the metal template and transferred to trapping sites at the vacuum interface of crystalline D(2)O islands. In these traps, the electrons are effectively decoupled from the electronic states of the metal template, leading to extraordinarily long excited state lifetimes on the order of minutes. Using these long-lived, low-energy electrons, we study the DEA to CFCl(3) that is coadsorbed at very low concentrations (∼10(12) cm(-2)). Using rate equations and direct measurement of the change of surface dipole moment, we estimated the electron surface density for DEA, yielding cross sections that are orders of magnitude higher than the electron density measured in the gas phase.

High-resolution, high-throughput imaging with a multibeam scanning electron microscope

PubMed Central

EBERLE, AL; MIKULA, S; SCHALEK, R; LICHTMAN, J; TATE, ML KNOTHE; ZEIDLER, D

2015-01-01

Electron–electron interactions and detector bandwidth limit the maximal imaging speed of single-beam scanning electron microscopes. We use multiple electron beams in a single column and detect secondary electrons in parallel to increase the imaging speed by close to two orders of magnitude and demonstrate imaging for a variety of samples ranging from biological brain tissue to semiconductor wafers. Lay Description The composition of our world and our bodies on the very small scale has always fascinated people, making them search for ways to make this visible to the human eye. Where light microscopes reach their resolution limit at a certain magnification, electron microscopes can go beyond. But their capability of visualizing extremely small features comes at the cost of a very small field of view. Some of the questions researchers seek to answer today deal with the ultrafine structure of brains, bones or computer chips. Capturing these objects with electron microscopes takes a lot of time – maybe even exceeding the time span of a human being – or new tools that do the job much faster. A new type of scanning electron microscope scans with 61 electron beams in parallel, acquiring 61 adjacent images of the sample at the same time a conventional scanning electron microscope captures one of these images. In principle, the multibeam scanning electron microscope’s field of view is 61 times larger and therefore coverage of the sample surface can be accomplished in less time. This enables researchers to think about large-scale projects, for example in the rather new field of connectomics. A very good introduction to imaging a brain at nanometre resolution can be found within course material from Harvard University on http://www.mcb80x.org/# as featured media entitled ‘connectomics’. PMID:25627873

Analysis of improvement in performance and design parameters for enhancing resolution in an atmospheric scanning electron microscope.

PubMed

Yoon, Yeo Hun; Kim, Seung Jae; Kim, Dong Hwan

2015-12-01

The scanning electron microscope is used in various fields to go beyond diffraction limits of the optical microscope. However, the electron pathway should be conducted in a vacuum so as not to scatter electrons. The pretreatment of the sample is needed for use in the vacuum. To directly observe large and fully hydrophilic samples without pretreatment, the atmospheric scanning electron microscope (ASEM) is needed. We developed an electron filter unit and an electron detector unit for implementation of the ASEM. The key of the electron filter unit is that electrons are transmitted while air molecules remain untransmitted through the unit. The electron detector unit collected the backscattered electrons. We conducted experiments using the selected materials with Havar foil, carbon film and SiN film. © The Author 2015. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Size determination of Acipenser ruthenus spermatozoa in different types of electron microscopy.

PubMed

Psenicka, Martin; Tesarová, Martina; Tesitel, Jakub; Nebesárová, Jana

2010-07-01

In this study three types of scanning electron microscopes were used for the size determination of spermatozoa of sterlet Acipenser ruthenus - high vacuum scanning electron microscope (SEM, JEOL 6300), environmental scanning electron microscope (ESEM, Quanta 200 FEG), field emission scanning electron microscope (FESEM, JEOL 7401F) with cryoattachment Alto 2500 (Gatan) and transmission electron microscope (TEM, JEOL 1010). The use of particular microscopes was tied with different specimen preparation techniques. The aim of this study was to evaluate to what degree the type of used electron microscope can influence the size of different parts of spermatozoa. For high vacuum SEM the specimen was prepared using two slightly different procedures. After chemical fixation with 2.5% glutaraldehyde in 0.1M phosphate buffer and post-fixation by 1% osmium tetroxide, the specimen was dehydrated by acetone series and dried either by critical point method or by means of t-butylalcohol. For ESEM fresh, unfixed material was used, which was dropped on microscopic copper grids. In FESEM working in cryo-mode the specimen was observed in a frozen state. Ultrathin sections from chemically fixed and Epon embedded specimens were prepared for TEM observation. Distinct parts of sterlet spermatozoa were measured in each microscope and the data obtained was statistically processed. Results confirmed that the classical chemical procedure of specimen preparation for SEM including critical point drying method led to a significant contraction of all measured values, which could deviate up to 30% in comparison with values measured on the fresh chemically untreated specimen in ESEM. Surprisingly sperm dimensions determinated on ultrathin sections by TEM are comparable with values obtained in ESEM or FESEM. Copyright 2010 Elsevier Ltd. All rights reserved.

ADP-glucose pyrophosphorylase is localized to both the cytoplasm and plastids in developing pericarp of tomato fruit

NASA Technical Reports Server (NTRS)

Chen, B. Y.; Wang, Y.; Janes, H. W.

1998-01-01

The intracellular location of ADP-glucose pyrophosphorylase (AGP) in developing pericarp of tomato (Lycopersicon esculentum Mill) has been investigated by immunolocalization. With the use of a highly specific anti-tomato fruit AGP antibody, the enzyme was localized in cytoplasm as well as plastids at both the light and electron microscope levels. The immunogold particles in plastids were localized in the stroma and at the surface of the starch granule, whereas those in the cytoplasm occurred in cluster-like patterns. Contrary to the fruit, the labeling in tomato leaf cells occurred exclusively in the chloroplasts. These data demonstrate that AGP is localized to both the cytoplasm and plastids in developing pericarp cells of tomato.

Reprint of: Atmospheric scanning electron microscope observes cells and tissues in open medium through silicon nitride film.

PubMed

Nishiyama, Hidetoshi; Suga, Mitsuo; Ogura, Toshihiko; Maruyama, Yuusuke; Koizumi, Mitsuru; Mio, Kazuhiro; Kitamura, Shinichi; Sato, Chikara

2010-11-01

Direct observation of subcellular structures and their characterization is essential for understanding their physiological functions. To observe them in open environment, we have developed an inverted scanning electron microscope with a detachable, open-culture dish, capable of 8 nm resolution, and combined with a fluorescence microscope quasi-simultaneously observing the same area from the top. For scanning electron microscopy from the bottom, a silicon nitride film window in the base of the dish maintains a vacuum between electron gun and open sample dish while allowing electrons to pass through. Electrons are backscattered from the sample and captured by a detector under the dish. Cells cultured on the open dish can be externally manipulated under optical microscopy, fixed, and observed using scanning electron microscopy. Once fine structures have been revealed by scanning electron microscopy, their component proteins may be identified by comparison with separately prepared fluorescence-labeled optical microscopic images of the candidate proteins, with their heavy-metal-labeled or stained ASEM images. Furthermore, cell nuclei in a tissue block stained with platinum-blue were successfully observed without thin-sectioning, which suggests the applicability of this inverted scanning electron microscope to cancer diagnosis. This microscope visualizes mesoscopic-scale structures, and is also applicable to non-bioscience fields including polymer chemistry. Copyright © 2010 Elsevier Inc. All rights reserved.

An electron microscope for the aberration-corrected era.

PubMed

Krivanek, O L; Corbin, G J; Dellby, N; Elston, B F; Keyse, R J; Murfitt, M F; Own, C S; Szilagyi, Z S; Woodruff, J W

2008-02-01

Improved resolution made possible by aberration correction has greatly increased the demands on the performance of all parts of high-end electron microscopes. In order to meet these demands, we have designed and built an entirely new scanning transmission electron microscope (STEM). The microscope includes a flexible illumination system that allows the properties of its probe to be changed on-the-fly, a third-generation aberration corrector which corrects all geometric aberrations up to fifth order, an ultra-responsive yet stable five-axis sample stage, and a flexible configuration of optimized detectors. The microscope features many innovations, such as a modular column assembled from building blocks that can be stacked in almost any order, in situ storage and cleaning facilities for up to five samples, computer-controlled loading of samples into the column, and self-diagnosing electronics. The microscope construction is described, and examples of its capabilities are shown.

Plasmonic Imaging of Electrochemical Reactions of Single Nanoparticles.

PubMed

Fang, Yimin; Wang, Hui; Yu, Hui; Liu, Xianwei; Wang, Wei; Chen, Hong-Yuan; Tao, N J

2016-11-15

Electrochemical reactions are involved in many natural phenomena, and are responsible for various applications, including energy conversion and storage, material processing and protection, and chemical detection and analysis. An electrochemical reaction is accompanied by electron transfer between a chemical species and an electrode. For this reason, it has been studied by measuring current, charge, or related electrical quantities. This approach has led to the development of various electrochemical methods, which have played an essential role in the understanding and applications of electrochemistry. While powerful, most of the traditional methods lack spatial and temporal resolutions desired for studying heterogeneous electrochemical reactions on electrode surfaces and in nanoscale materials. To overcome the limitations, scanning probe microscopes have been invented to map local electrochemical reactions with nanometer resolution. Examples include the scanning electrochemical microscope and scanning electrochemical cell microscope, which directly image local electrochemical reaction current using a scanning electrode or pipet. The use of a scanning probe in these microscopes provides high spatial resolution, but at the expense of temporal resolution and throughput. This Account discusses an alternative approach to study electrochemical reactions. Instead of measuring electron transfer electrically, it detects the accompanying changes in the reactant and product concentrations on the electrode surface optically via surface plasmon resonance (SPR). SPR is highly surface sensitive, and it provides quantitative information on the surface concentrations of reactants and products vs time and electrode potential, from which local reaction kinetics can be analyzed and quantified. The plasmonic approach allows imaging of local electrochemical reactions with high temporal resolution and sensitivity, making it attractive for studying electrochemical reactions in biological systems and nanoscale materials with high throughput. The plasmonic approach has two imaging modes: electrochemical current imaging and interfacial impedance imaging. The former images local electrochemical current associated with electrochemical reactions (faradic current), and the latter maps local interfacial impedance, including nonfaradic contributions (e.g., double layer charging). The plasmonic imaging technique can perform voltammetry (cyclic or square wave) in an analogous manner to the traditional electrochemical methods. It can also be integrated with bright field, dark field, and fluorescence imaging capabilities in one optical setup to provide additional capabilities. To date the plasmonic imaging technique has found various applications, including mapping of heterogeneous surface reactions, analysis of trace substances, detection of catalytic reactions, and measurement of graphene quantum capacitance. The plasmonic and other emerging optical imaging techniques (e.g., dark field and fluorescence microscopy), together with the scanning probe-based electrochemical imaging and single nanoparticle analysis techniques, provide new capabilities for one to study single nanoparticle electrochemistry with unprecedented spatial and temporal resolutions. In this Account, we focus on imaging of electrochemical reactions at single nanoparticles.

Hartmann characterization of the PEEM-3 aberration-corrected X-ray photoemission electron microscope.

PubMed

Scholl, A; Marcus, M A; Doran, A; Nasiatka, J R; Young, A T; MacDowell, A A; Streubel, R; Kent, N; Feng, J; Wan, W; Padmore, H A

2018-05-01

Aberration correction by an electron mirror dramatically improves the spatial resolution and transmission of photoemission electron microscopes. We will review the performance of the recently installed aberration corrector of the X-ray Photoemission Electron Microscope PEEM-3 and show a large improvement in the efficiency of the electron optics. Hartmann testing is introduced as a quantitative method to measure the geometrical aberrations of a cathode lens electron microscope. We find that aberration correction leads to an order of magnitude reduction of the spherical aberrations, suggesting that a spatial resolution of below 100 nm is possible at 100% transmission of the optics when using x-rays. We demonstrate this improved performance by imaging test patterns employing element and magnetic contrast. Published by Elsevier B.V.

ultraLM and miniLM: Locator tools for smart tracking of fluorescent cells in correlative light and electron microscopy.

PubMed

Brama, Elisabeth; Peddie, Christopher J; Wilkes, Gary; Gu, Yan; Collinson, Lucy M; Jones, Martin L

2016-12-13

In-resin fluorescence (IRF) protocols preserve fluorescent proteins in resin-embedded cells and tissues for correlative light and electron microscopy, aiding interpretation of macromolecular function within the complex cellular landscape. Dual-contrast IRF samples can be imaged in separate fluorescence and electron microscopes, or in dual-modality integrated microscopes for high resolution correlation of fluorophore to organelle. IRF samples also offer a unique opportunity to automate correlative imaging workflows. Here we present two new locator tools for finding and following fluorescent cells in IRF blocks, enabling future automation of correlative imaging. The ultraLM is a fluorescence microscope that integrates with an ultramicrotome, which enables 'smart collection' of ultrathin sections containing fluorescent cells or tissues for subsequent transmission electron microscopy or array tomography. The miniLM is a fluorescence microscope that integrates with serial block face scanning electron microscopes, which enables 'smart tracking' of fluorescent structures during automated serial electron image acquisition from large cell and tissue volumes.

Spherical aberration correction in a scanning transmission electron microscope using a sculpted thin film.

PubMed

Shiloh, Roy; Remez, Roei; Lu, Peng-Han; Jin, Lei; Lereah, Yossi; Tavabi, Amir H; Dunin-Borkowski, Rafal E; Arie, Ady

2018-06-01

Nearly eighty years ago, Scherzer showed that rotationally symmetric, charge-free, static electron lenses are limited by an unavoidable, positive spherical aberration. Following a long struggle, a major breakthrough in the spatial resolution of electron microscopes was reached two decades ago by abandoning the first of these conditions, with the successful development of multipole aberration correctors. Here, we use a refractive silicon nitride thin film to tackle the second of Scherzer's constraints and demonstrate an alternative method for correcting spherical aberration in a scanning transmission electron microscope. We reveal features in Si and Cu samples that cannot be resolved in an uncorrected microscope. Our thin film corrector can be implemented as an immediate low cost upgrade to existing electron microscopes without re-engineering of the electron column or complicated operation protocols and can be extended to the correction of additional aberrations. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

Microstructure Evolution and Mechanical Properties of Underwater Dry and Local Dry Cavity Welded Joints of 690 MPa Grade High Strength Steel

PubMed Central

Sun, Kun; Cui, Shuwan; Zeng, Min; Yi, Jianglong; Shen, Xiaoqin; Yi, Yaoyong

2018-01-01

Q690E high strength low alloy (HSLA) steel plays an important role in offshore structures. In addition, underwater local cavity welding (ULCW) technique was widely used to repair important offshore constructions. However, the high cooling rate of ULCW joints results in bad welding quality compared with underwater dry welding (UDW) joints. Q690E high strength low alloy steels were welded by multi-pass UDW and ULCW techniques, to study the microstructural evolution and mechanical properties of underwater welded joints. The microstructure and fracture morphology of welded joints were observed by scanning electron microscope and optical microscope. The elemental distribution in the microstructure was determined with an Electron Probe Microanalyzer. The results indicated that the microstructure of both two welded joints was similar. However, martensite and martensite-austenite components were significantly different with different underwater welding methods such that the micro-hardness of the HAZ and FZ in the ULCW specimen was higher than that of the corresponding regions in UDW joint. The yield strength and ultimate tensile strength of the ULCW specimen are 109 MPa lower and 77 MPa lower, respectively, than those of the UDW joint. The impact toughness of the UDW joint was superior to those of the ULCW joint. PMID:29361743

Microstructure Evolution and Mechanical Properties of Underwater Dry and Local Dry Cavity Welded Joints of 690 MPa Grade High Strength Steel.

PubMed

Shi, Yonghua; Sun, Kun; Cui, Shuwan; Zeng, Min; Yi, Jianglong; Shen, Xiaoqin; Yi, Yaoyong

2018-01-22

Q690E high strength low alloy (HSLA) steel plays an important role in offshore structures. In addition, underwater local cavity welding (ULCW) technique was widely used to repair important offshore constructions. However, the high cooling rate of ULCW joints results in bad welding quality compared with underwater dry welding (UDW) joints. Q690E high strength low alloy steels were welded by multi-pass UDW and ULCW techniques, to study the microstructural evolution and mechanical properties of underwater welded joints. The microstructure and fracture morphology of welded joints were observed by scanning electron microscope and optical microscope. The elemental distribution in the microstructure was determined with an Electron Probe Microanalyzer. The results indicated that the microstructure of both two welded joints was similar. However, martensite and martensite-austenite components were significantly different with different underwater welding methods such that the micro-hardness of the HAZ and FZ in the ULCW specimen was higher than that of the corresponding regions in UDW joint. The yield strength and ultimate tensile strength of the ULCW specimen are 109 MPa lower and 77 MPa lower, respectively, than those of the UDW joint. The impact toughness of the UDW joint was superior to those of the ULCW joint.

Fully microscopic analysis of laser-driven finite plasmas using the example of clusters

NASA Astrophysics Data System (ADS)

Peltz, Christian; Varin, Charles; Brabec, Thomas; Fennel, Thomas

2012-06-01

We discuss a microscopic particle-in-cell (MicPIC) approach that allows bridging of the microscopic and macroscopic realms of laser-driven plasma physics. The simultaneous resolution of collisions and electromagnetic field propagation in MicPIC enables the investigation of processes that have been inaccessible to rigorous numerical scrutiny so far. This is illustrated by the two main findings of our analysis of pre-ionized, resonantly laser-driven clusters, which can be realized experimentally in pump-probe experiments. In the linear response regime, MicPIC data are used to extract the individual microscopic contributions to the dielectric cluster response function, such as surface and bulk collision frequencies. We demonstrate that the competition between surface collisions and radiation damping is responsible for the maximum in the size-dependent lifetime of the Mie surface plasmon. The capacity to determine the microscopic underpinning of optical material parameters opens new avenues for modeling nano-plasmonics and nano-photonics systems. In the non-perturbative regime, we analyze the formation and evolution of recollision-induced plasma waves in laser-driven clusters. The resulting dynamics of the electron density and local field hot spots opens a new research direction for the field of attosecond science.

β-relaxation related bright bands in thin film metallic glasses: Localized percolation of flow units captured via transmission electron microscope

NASA Astrophysics Data System (ADS)

Chen, Z. Q.; Huang, P.; Xu, K. W.; Wang, F.; Lu, T. J.

2016-12-01

We report that β-relaxation of amorphous NiW alloy film was effectively enhanced by adding two thin crystalline layers into the amorphous layer. Correspondingly, more bright bands, i.e., nano shear bands, were captured in the amorphous layer, which experienced more pronounced β-relaxations. Based on the potential energy landscape theory, the bright band was proposed to be the localized percolation of flow units corresponding to β-relaxation. Our findings may help connecting experimentally β-relaxation with flow units and shed light on the microstructure origin of β-relaxation.

A method to characterize the roughness of 2-D line features: recrystallization boundaries.

PubMed

Sun, J; Zhang, Y B; Dahl, A B; Conradsen, K; Juul Jensen, D

2017-03-01

A method is presented, which allows quantification of the roughness of nonplanar boundaries of objects for which the neutral plane is not known. The method provides quantitative descriptions of both the local and global characteristics. How the method can be used to estimate the sizes of rough features and local curvatures is also presented. The potential of the method is illustrated by quantification of the roughness of two recrystallization boundaries in a pure Al specimen characterized by scanning electron microscopy. © 2016 The Authors Journal of Microscopy © 2016 Royal Microscopical Society.

Construction of imaging system for wide-field-range ESR spectra using localized microwave field and its case study of crystal orientation in suspension of copper sulfate pentahydrate (CuSO4 . 5H2O).

PubMed

Tani, Atsushi; Ueno, Takehiro; Yamanaka, Chihiro; Katsura, Makoto; Ikeya, Motoji

2005-02-01

A scanning electron spin resonance (ESR) microscope using a localized microwave field was redesigned to measure ESR spectra from 0 to 400 mT using electromagnets. Divalent copper ion (Cu2+) in copper sulfate pentahydrate (CuSO4 . 5H2O) was imaged, after the powdered samples were cemented in silicone rubber under a magnetic field. The ratio of the two signal intensities at g=2.27 and 2.08 clearly indicates the orientation of the particles. This method can be used for mapping the local magnetic field and its direction.

Scanning electron microscope observation of dislocations in semiconductor and metal materials.

PubMed

Kuwano, Noriyuki; Itakura, Masaru; Nagatomo, Yoshiyuki; Tachibana, Shigeaki

2010-08-01

Scanning electron microscope (SEM) image contrasts have been investigated for dislocations in semiconductor and metal materials. It is revealed that single dislocations can be observed in a high contrast in SEM images formed by backscattered electrons (BSE) under the condition of a normal configuration of SEM. The BSE images of dislocations were compared with those of the transmission electron microscope and scanning transmission electron microscope (STEM) and the dependence of BSE image contrast on the tilting of specimen was examined to discuss the origin of image contrast. From the experimental results, it is concluded that the BSE images of single dislocations are attributed to the diffraction effect and related with high-angle dark-field images of STEM.

Flexible high-voltage supply for experimental electron microscope

NASA Technical Reports Server (NTRS)

Chapman, G. L.; Jung, E. A.; Lewis, R. N.; Van Loon, L. S.; Welter, L. M.

1969-01-01

Scanning microscope uses a field-emission tip for the electron source, an electron gun that simultaneously accelerates and focuses electrons from the source, and one auxiliary lens to produce a final probe size at the specimen on the order of angstroms.

Rewritable ghost floating gates by tunnelling triboelectrification for two-dimensional electronics

PubMed Central

Kim, Seongsu; Kim, Tae Yun; Lee, Kang Hyuck; Kim, Tae-Ho; Cimini, Francesco Arturo; Kim, Sung Kyun; Hinchet, Ronan; Kim, Sang-Woo; Falconi, Christian

2017-01-01

Gates can electrostatically control charges inside two-dimensional materials. However, integrating independent gates typically requires depositing and patterning suitable insulators and conductors. Moreover, after manufacturing, gates are unchangeable. Here we introduce tunnelling triboelectrification for localizing electric charges in very close proximity of two-dimensional materials. As representative materials, we use chemical vapour deposition graphene deposited on a SiO2/Si substrate. The triboelectric charges, generated by friction with a Pt-coated atomic force microscope tip and injected through defects, are trapped at the air–SiO2 interface underneath graphene and act as ghost floating gates. Tunnelling triboelectrification uniquely permits to create, modify and destroy p and n regions at will with the spatial resolution of atomic force microscopes. As a proof of concept, we draw rewritable p/n+ and p/p+ junctions with resolutions as small as 200 nm. Our results open the way to time-variant two-dimensional electronics where conductors, p and n regions can be defined on demand. PMID:28649986

Rewritable ghost floating gates by tunnelling triboelectrification for two-dimensional electronics

NASA Astrophysics Data System (ADS)

Kim, Seongsu; Kim, Tae Yun; Lee, Kang Hyuck; Kim, Tae-Ho; Cimini, Francesco Arturo; Kim, Sung Kyun; Hinchet, Ronan; Kim, Sang-Woo; Falconi, Christian

2017-06-01

Gates can electrostatically control charges inside two-dimensional materials. However, integrating independent gates typically requires depositing and patterning suitable insulators and conductors. Moreover, after manufacturing, gates are unchangeable. Here we introduce tunnelling triboelectrification for localizing electric charges in very close proximity of two-dimensional materials. As representative materials, we use chemical vapour deposition graphene deposited on a SiO2/Si substrate. The triboelectric charges, generated by friction with a Pt-coated atomic force microscope tip and injected through defects, are trapped at the air-SiO2 interface underneath graphene and act as ghost floating gates. Tunnelling triboelectrification uniquely permits to create, modify and destroy p and n regions at will with the spatial resolution of atomic force microscopes. As a proof of concept, we draw rewritable p/n+ and p/p+ junctions with resolutions as small as 200 nm. Our results open the way to time-variant two-dimensional electronics where conductors, p and n regions can be defined on demand.

Scanning-electron-microscope used in real-time study of friction and wear

NASA Technical Reports Server (NTRS)

Brainard, W. A.; Buckley, D. H.

1975-01-01

Small friction and wear apparatus built directly into scanning-electron-microscope provides both dynamic observation and microscopic view of wear process. Friction and wear tests conducted using this system have indicated that considerable information can readily be gained.

Thermal-Wave Microscope

NASA Technical Reports Server (NTRS)

Jones, Robert E.; Kramarchuk, Ihor; Williams, Wallace D.; Pouch, John J.; Gilbert, Percy

1989-01-01

Computer-controlled thermal-wave microscope developed to investigate III-V compound semiconductor devices and materials. Is nondestructive technique providing information on subsurface thermal features of solid samples. Furthermore, because this is subsurface technique, three-dimensional imaging also possible. Microscope uses intensity-modulated electron beam of modified scanning electron microscope to generate thermal waves in sample. Acoustic waves generated by thermal waves received by transducer and processed in computer to form images displayed on video display of microscope or recorded on magnetic disk.

Skeletal muscle biopsy analysis in reducing body myopathy and other FHL1-related disorders.

PubMed

Malfatti, Edoardo; Olivé, Montse; Taratuto, Ana Lía; Richard, Pascale; Brochier, Guy; Bitoun, Marc; Gueneau, Lucie; Laforêt, Pascal; Stojkovic, Tanya; Maisonobe, Thierry; Monges, Soledad; Lubieniecki, Fabiana; Vasquez, Gabriel; Streichenberger, Nathalie; Lacène, Emmanuelle; Saccoliti, Maria; Prudhon, Bernard; Alexianu, Marilena; Figarella-Branger, Dominique; Schessl, Joachim; Bonnemann, Carsten; Eymard, Bruno; Fardeau, Michel; Bonne, Gisèle; Romero, Norma Beatriz

2013-09-01

FHL1 mutations have been associated with various disorders that include reducing body myopathy (RBM), Emery-Dreifuss-like muscular dystrophy, isolated hypertrophic cardiomyopathy, and some overlapping conditions. We report a detailed histochemical, immunohistochemical, electron microscopic, and immunoelectron microscopic analyses of muscle biopsies from 18 patients carrying mutations in FHL1: 14 RBM patients (Group 1), 3 Emery-Dreifuss muscular dystrophy patients (Group 2), and 1 patient with hypertrophic cardiomyopathy and muscular hypertrophy (Group 2). Group 1 muscle biopsies consistently showed RBs associated with cytoplasmic bodies. The RBs showed prominent FHL1 immunoreactivity whereas desmin, αB-crystallin, and myotilin immunoreactivity surrounded RBs. By electron microscopy, RBs were composed of electron-dense tubulofilamentous material that seemed to spread progressively between the myofibrils and around myonuclei. By immunoelectron microscopy, FHL1 protein was found exclusively inside RBs. Group 2 biopsies showed mild dystrophic abnormalities without RBs; only minor nonspecific myofibrillar abnormalities were observed under electron microscopy. Molecular analysis revealed missense mutations in the second FHL1 LIM domain in Group 1 patients and ins/del or missense mutations within the fourth FHL1 LIM domain in Group 2 patients. Our findings expand the morphologic features of RBM, clearly demonstrate the localization of FHL1 in RBs, and further illustrate major morphologic differences among different FHL1-related myopathies.

Computation of the influence of scanning probe microscope (SPM) on quantum dot eigenstates and 2DEG potential

NASA Astrophysics Data System (ADS)

Stopa, Michael

2005-03-01

We calculate the electronic structure of GaAs-AlGaAs two-dimensional electron gas (2DEG) devices, such as quantum dots and quantum point contacts (QPCs) in the presence of a tip of a scanning probe microscope at some distance above the surface. The calculation employs standard density functional theory with exchange and correlation treated in the local density approximation. The position and voltage on the tip are varied and the conditions for depletion of the 2DEG are shown to compare favorably to experiment [1]. We show that the size of the depletion region created (by a negative tip voltage) is unexpectedly small due to focusing of the potential lines by the higher dielectric. We study the interaction of the tip with an isolated quantum dot that contains one or two electrons. The raster pattern of the difference between single particle energies reveals that the tip distorts the shape of the confining potential and suggests that excited state properties, if they can be measured experimentally, can contribute to the resolution of spatial information. [1] M.A. Topinka, R.M. Westervelt, E.J. Heller, ``http://meso.deas.harvard.edu/papers/Topinka, PT 56 12 (2003)'' (Imaging Electron Flow), Physics Today 56, 12 (2003).

Electron Microscopy Localization and Characterization of Functionalized Composite Organic-Inorganic SERS Nanoparticles on Leukemia Cells

PubMed Central

Koh, Ai Leen; Shachaf, Catherine M.; Elchuri, Sailaja; Nolan, Garry P.; Sinclair, Robert

2008-01-01

We demonstrate the use of electron microscopy as a powerful characterization tool to identify and locate antibody-conjugated composite organic-inorganic (COINs) surface enhanced Raman scattering (SERS) nanoparticles on cells. U937 leukemia cells labeled with antibody CD54-conjugated COINs were characterized in their native, hydrated state using wet Scanning Electron Microscopy (SEM) and in their dehydrated state using high-resolution SEM. In both cases, the backscattered electron detector (BSE) was used to detect and identify the silver constituents in COINs due to its high sensitivity to atomic number variations within a specimen. The imaging and analytical capabilities in the SEM were further complemented by higher resolution Transmission Electron Microscope (TEM) images and Scanning Auger Electron Spectroscopy (AES) data to give reliable and high-resolution information about nanoparticles and their binding to cell surface antigens. PMID:18995965

Quantification of Nanoscale Density Fluctuations in Biological Cells/Tissues: Inverse Participation Ratio (IPR) Analysis of Transmission Electron Microscopy Images and Implications for Early-Stage Cancer Detection

NASA Astrophysics Data System (ADS)

Pradhan, Prabhakar; Damania, Dhwanil; Joshi, Hrushikesh; Taflove, Allen; Roy, Hemant; Dravid, Vinayak; Backman, Vadim

2010-03-01

We report a study of the nanoscale mass density fluctuations of biological cells and tissues by quantifying their nanoscale light-localization properties. Transmission electron microscope (TEM) images of human cells and tissues are used to construct corresponding effective disordered optical lattices. Light-localization properties are studied by statistical analysis of the inverse participation ratio (IPR) of the eigenfunctions of these optical lattices at the nanoscales. Our results indicate elevation of the nanoscale disorder strength (e.g., refractive index fluctuations) in early carcinogenesis. Importantly, our results demonstrate that the increase in the nanoscale disorder represents the earliest structural alteration in cells undergoing carcinogenesis known to-date. Potential applications of the technique for early stage cancer detection will be discussed.

Probing the symmetry of the potential of localized surface plasmon resonances with phase-shaped electron beams

PubMed Central

Guzzinati, Giulio; Béché, Armand; Lourenço-Martins, Hugo; Martin, Jérôme; Kociak, Mathieu; Verbeeck, Jo

2017-01-01

Plasmonics, the science and technology of the interaction of light with metallic objects, is fundamentally changing the way we can detect, generate and manipulate light. Although the field is progressing swiftly, thanks to the availability of nanoscale manufacturing and analysis methods, fundamental properties such as the plasmonic excitations' symmetries cannot be accessed directly, leading to a partial, sometimes incorrect, understanding of their properties. Here we overcome this limitation by deliberately shaping the wave function of an electron beam to match a plasmonic excitations' symmetry in a modified transmission electron microscope. We show experimentally and theoretically that this offers selective detection of specific plasmon modes within metallic nanoparticles, while excluding modes with other symmetries. This method resembles the widespread use of polarized light for the selective excitation of plasmon modes with the advantage of locally probing the response of individual plasmonic objects and a far wider range of symmetry selection criteria. PMID:28401942

In situ transmission electron microscopy of lead dendrites and lead ions in aqueous solution.

PubMed

White, Edward R; Singer, Scott B; Augustyn, Veronica; Hubbard, William A; Mecklenburg, Matthew; Dunn, Bruce; Regan, Brian C

2012-07-24

An ideal technique for observing nanoscale assembly would provide atomic-resolution images of both the products and the reactants in real time. Using a transmission electron microscope we image in situ the electrochemical deposition of lead from an aqueous solution of lead(II) nitrate. Both the lead deposits and the local Pb(2+) concentration can be visualized. Depending on the rate of potential change and the potential history, lead deposits on the cathode in a structurally compact layer or in dendrites. In both cases the deposits can be removed and the process repeated. Asperities that persist through many plating and stripping cycles consistently nucleate larger dendrites. Quantitative digital image analysis reveals excellent correlation between changes in the Pb(2+) concentration, the rate of lead deposition, and the current passed by the electrochemical cell. Real-time electron microscopy of dendritic growth dynamics and the associated local ionic concentrations can provide new insight into the functional electrochemistry of batteries and related energy storage technologies.

Nanometres-resolution Kikuchi patterns from materials science specimens with transmission electron forward scatter diffraction in the scanning electron microscope.

PubMed

Brodusch, N; Demers, H; Gauvin, R

2013-04-01

A charge-coupled device camera of an electron backscattered diffraction system in a scanning electron microscope was positioned below a thin specimen and transmission Kikuchi patterns were collected. Contrary to electron backscattered diffraction, transmission electron forward scatter diffraction provides phase identification and orientation mapping at the nanoscale. The minimum Pd particle size for which a Kikuchi diffraction pattern was detected and indexed reliably was 5.6 nm. An orientation mapping resolution of 5 nm was measured at 30 kV. The resolution obtained with transmission electron forward scatter diffraction was of the same order of magnitude than that reported in electron nanodiffraction in the transmission electron microscope. An energy dispersive spectrometer X-ray map and a transmission electron forward scatter diffraction orientation map were acquired simultaneously. The high-resolution chemical, phase and orientation maps provided at once information on the chemical form, orientation and coherency of precipitates in an aluminium-lithium 2099 alloy. © 2013 The Authors Journal of Microscopy © 2013 Royal Microscopical Society.

Evidence of sharp and diffuse domain walls in BiFeO3 by means of unit-cell-wise strain and polarization maps obtained with high resolution scanning transmission electron microscopy.

PubMed

Lubk, A; Rossell, M D; Seidel, J; He, Q; Yang, S Y; Chu, Y H; Ramesh, R; Hÿtch, M J; Snoeck, E

2012-07-27

Domain walls (DWs) substantially influence a large number of applications involving ferroelectric materials due to their limited mobility when shifted during polarization switching. The discovery of greatly enhanced conduction at BiFeO(3) DWs has highlighted yet another role of DWs as a local material state with unique properties. However, the lack of precise information on the local atomic structure is still hampering microscopical understanding of DW properties. Here, we examine the atomic structure of BiFeO(3) 109° DWs with pm precision by a combination of high-angle annular dark-field scanning transmission electron microscopy and a dedicated structural analysis. By measuring simultaneously local polarization and strain, we provide direct experimental proof for the straight DW structure predicted by ab initio calculations as well as the recently proposed theory of diffuse DWs, thus resolving a long-standing discrepancy between experimentally measured and theoretically predicted DW mobilities.

Electrical characterization of HgTe nanowires using conductive atomic force microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gundersen, P.; Department of Physics, Norwegian University of Science and Technology, NO-7491 Trondheim; Kongshaug, K. O.

Self-organized HgTe nanowires grown by molecular beam epitaxy (MBE) have been characterized using conductive atomic force microscopy. As HgTe will degrade or evaporate at normal baking temperatures for electron beam lithography (EBL) resists, an alternative method was developed. Using low temperature optical lithography processes, large Au contacts were deposited on a sample covered with randomly oriented, lateral HgTe nanowires. Nanowires partly covered by the large electrodes were identified with a scanning electron microscope and then localized in the atomic force microscope (AFM). The conductive tip of the AFM was then used as a movable electrode to measure current-voltage curves atmore » several locations on HgTe nanowires. The measurements revealed that polycrystalline nanowires had diffusive electron transport, with resistivities two orders of magnitude larger than that of an MBE-grown HgTe film. The difference can be explained by scattering at the rough surface walls and at the grain boundaries in the wires. The method can be a solution when EBL is not available or requires too high temperature, or when measurements at several positions along a wire are required.« less

Conductive resins improve charging and resolution of acquired images in electron microscopic volume imaging

PubMed Central

Nguyen, Huy Bang; Thai, Truc Quynh; Saitoh, Sei; Wu, Bao; Saitoh, Yurika; Shimo, Satoshi; Fujitani, Hiroshi; Otobe, Hirohide; Ohno, Nobuhiko

2016-01-01

Recent advances in serial block-face imaging using scanning electron microscopy (SEM) have enabled the rapid and efficient acquisition of 3-dimensional (3D) ultrastructural information from a large volume of biological specimens including brain tissues. However, volume imaging under SEM is often hampered by sample charging, and typically requires specific sample preparation to reduce charging and increase image contrast. In the present study, we introduced carbon-based conductive resins for 3D analyses of subcellular ultrastructures, using serial block-face SEM (SBF-SEM) to image samples. Conductive resins were produced by adding the carbon black filler, Ketjen black, to resins commonly used for electron microscopic observations of biological specimens. Carbon black mostly localized around tissues and did not penetrate cells, whereas the conductive resins significantly reduced the charging of samples during SBF-SEM imaging. When serial images were acquired, embedding into the conductive resins improved the resolution of images by facilitating the successful cutting of samples in SBF-SEM. These results suggest that improving the conductivities of resins with a carbon black filler is a simple and useful option for reducing charging and enhancing the resolution of images obtained for volume imaging with SEM. PMID:27020327

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sato, Chikara, E-mail: ti-sato@aist.go.jp; Manaka, Sachie; Nakane, Daisuke

Highlights: Black-Right-Pointing-Pointer Mycoplasma mobile was observed in buffer with the Atmospheric Scanning Electron Microscope. Black-Right-Pointing-Pointer Characteristic protein localizations were visualized using immuno-labeling. Black-Right-Pointing-Pointer M. mobile attached to sialic acid on the SiN film surface within minutes. Black-Right-Pointing-Pointer Cells were observed at low concentrations. Black-Right-Pointing-Pointer ASEM should promote study and early-stage diagnosis of mycoplasma. -- Abstract: Mycoplasma is a genus of bacterial pathogen that causes disease in vertebrates. In humans, the species Mycoplasma pneumoniae causes 15% or more of community-acquired pneumonia. Because this bacterium is tiny, corresponding in size to a large virus, diagnosis using optical microscopy is not easy. Inmore » current methods, chest X-rays are usually the first action, followed by serology, PCR amplification, and/or culture, but all of these are particularly difficult at an early stage of the disease. Using Mycoplasma mobile as a model species, we directly observed mycoplasma in buffer with the newly developed Atmospheric Scanning Electron Microscope (ASEM). This microscope features an open sample dish with a pressure-resistant thin film window in its base, through which the SEM beam scans samples in solution, from below. Because of its 2-3 {mu}m-deep scanning capability, it can observe the whole internal structure of mycoplasma cells stained with metal solutions. Characteristic protein localizations were visualized using immuno-labeling. Cells were observed at low concentrations, because suspended cells concentrate in the observable zone by attaching to sialic acid on the silicon nitride (SiN) film surface within minutes. These results suggest the applicability of the ASEM for the study of mycoplasmas as well as for early-stage mycoplasma infection diagnosis.« less

Evaluation of local anesthetic effects of Lidocaine-Ibuprofen ionic liquid stabilized silver nanoparticles in Male Swiss mice.

PubMed

Jiang, Qiliang; Yu, Shashuang; Li, Xingwang; Ma, Chuangen; Li, Aixiang

2018-01-01

A simple approach for the synthesis of Lidocaine-Ibuprofen ionic liquid stabilized silver nanoparticles (IL-AgNPs) was reported in this work. The shape, size and surface morphology of the Lidocaine-Ibuprofen ionic liquid stabilized AgNPs were characterized by using spectroscopic and microscopic techniques such as Ultraviolet-visible spectroscopy (UV-Visible), X-ray diffraction (XRD) analysis, Selected area electron diffraction (SAED), Transmission electron microscopy (TEM). TEM analysis showed the formation of 20-30nm size of IL-AgNPs with very clear lattice fringes. SAED pattern confirmed the highly crystalline nature of fabricated IL stabilized AgNPs. EDS results confirmed the formation of nanosilver. The fabricated IL-AgNPs were studied for their local anesthetic effect in rats. The results of local anesthetic effect showed that the time for onset of action by IL-AgNPs is 10min, which is significantly higher than that for EMLA. Further, tactile test results confirmed the stronger and faster local anesthetic effect of IL-AgNPs when compared to that of EMLA. Copyright © 2017. Published by Elsevier B.V.

Nanoscale characterization of local structures and defects in photonic crystals using synchrotron-based transmission soft X-ray microscopy

PubMed Central

Nho, Hyun Woo; Kalegowda, Yogesh; Shin, Hyun-Joon; Yoon, Tae Hyun

2016-01-01

For the structural characterization of the polystyrene (PS)-based photonic crystals (PCs), fast and direct imaging capabilities of full field transmission X-ray microscopy (TXM) were demonstrated at soft X-ray energy. PS-based PCs were prepared on an O2-plasma treated Si3N4 window and their local structures and defects were investigated using this label-free TXM technique with an image acquisition speed of ~10 sec/frame and marginal radiation damage. Micro-domains of face-centered cubic (FCC (111)) and hexagonal close-packed (HCP (0001)) structures were dominantly found in PS-based PCs, while point and line defects, FCC (100), and 12-fold symmetry structures were also identified as minor components. Additionally, in situ observation capability for hydrated samples and 3D tomographic reconstruction of TXM images were also demonstrated. This soft X-ray full field TXM technique with faster image acquisition speed, in situ observation, and 3D tomography capability can be complementally used with the other X-ray microscopic techniques (i.e., scanning transmission X-ray microscopy, STXM) as well as conventional characterization methods (e.g., electron microscopic and optical/fluorescence microscopic techniques) for clearer structure identification of self-assembled PCs and better understanding of the relationship between their structures and resultant optical properties. PMID:27087141

Correlative light and electron microscopic detection of GFP-labeled proteins using modular APEX.

PubMed

Ariotti, Nicholas; Hall, Thomas E; Parton, Robert G

2017-01-01

The use of green fluorescent protein (GFP) and related proteins has revolutionized light microscopy. Here we describe a rapid and simple method to localize GFP-tagged proteins in cells and in tissues by electron microscopy (EM) using a modular approach involving a small GFP-binding peptide (GBP) fused to the ascorbate peroxidase-derived APEX2 tag. We provide a method for visualizing GFP-tagged proteins by light and EM in cultured cells and in the zebrafish using modular APEX-GBP. Furthermore, we describe in detail the benefits of this technique over many of the currently available correlative light and electron microscopy approaches and demonstrate APEX-GBP is readily applicable to modern three-dimensional techniques. Copyright © 2017 Elsevier Inc. All rights reserved.

Scanning electron microscope fine tuning using four-bar piezoelectric actuated mechanism

NASA Astrophysics Data System (ADS)

Hatamleh, Khaled S.; Khasawneh, Qais A.; Al-Ghasem, Adnan; Jaradat, Mohammad A.; Sawaqed, Laith; Al-Shabi, Mohammad

2018-01-01

Scanning Electron Microscopes are extensively used for accurate micro/nano images exploring. Several strategies have been proposed to fine tune those microscopes in the past few years. This work presents a new fine tuning strategy of a scanning electron microscope sample table using four bar piezoelectric actuated mechanisms. The introduced paper presents an algorithm to find all possible inverse kinematics solutions of the proposed mechanism. In addition, another algorithm is presented to search for the optimal inverse kinematic solution. Both algorithms are used simultaneously by means of a simulation study to fine tune a scanning electron microscope sample table through a pre-specified circular or linear path of motion. Results of the study shows that, proposed algorithms were able to minimize the power required to drive the piezoelectric actuated mechanism by a ratio of 97.5% for all simulated paths of motion when compared to general non-optimized solution.

Electronic transport in gadolinium atomic-size contacts

NASA Astrophysics Data System (ADS)

Olivera, B.; Salgado, C.; Lado, J. L.; Karimi, A.; Henkel, V.; Scheer, E.; Fernández-Rossier, J.; Palacios, J. J.; Untiedt, C.

2017-02-01

We report on the fabrication, transport measurements, and density functional theory (DFT) calculations of atomic-size contacts made of gadolinium (Gd). Gd is known to have local moments mainly associated with f electrons. These coexist with itinerant s and d bands that account for its metallic character. Here we explore whether and how the local moments influence electronic transport properties at the atomic scale. Using both scanning tunneling microscope and lithographic mechanically controllable break junction techniques under cryogenic conditions, we study the conductance of Gd when only few atoms form the junction between bulk electrodes made of the very same material. Thousands of measurements show that Gd has an average lowest conductance, attributed to single-atom contact, below 2/e2 h . Our DFT calculations for monostrand chains anticipate that the f bands are fully spin polarized and insulating and that the conduction may be dominated by s , p , and d bands. We also analyze the electronic transport for model nanocontacts using the nonequilibrium Green's function formalism in combination with DFT. We obtain an overall good agreement with the experimental results for zero bias and show that the contribution to the electronic transport from the f channels is negligible and that from the d channels is marginal.

Towards native-state imaging in biological context in the electron microscope

PubMed Central

Weston, Anne E.; Armer, Hannah E. J.

2009-01-01

Modern cell biology is reliant on light and fluorescence microscopy for analysis of cells, tissues and protein localisation. However, these powerful techniques are ultimately limited in resolution by the wavelength of light. Electron microscopes offer much greater resolution due to the shorter effective wavelength of electrons, allowing direct imaging of sub-cellular architecture. The harsh environment of the electron microscope chamber and the properties of the electron beam have led to complex chemical and mechanical preparation techniques, which distance biological samples from their native state and complicate data interpretation. Here we describe recent advances in sample preparation and instrumentation, which push the boundaries of high-resolution imaging. Cryopreparation, cryoelectron microscopy and environmental scanning electron microscopy strive to image samples in near native state. Advances in correlative microscopy and markers enable high-resolution localisation of proteins. Innovation in microscope design has pushed the boundaries of resolution to atomic scale, whilst automatic acquisition of high-resolution electron microscopy data through large volumes is finally able to place ultrastructure in biological context. PMID:19916039

ELECTRON MICROSCOPIC STUDY OF THE ATPASE ACTIVITY OF THE BAI STRAIN A (MYELOBLASTOSIS) AVIAN TUMOR VIRUS

PubMed Central

Novikoff, Alex B.; de Thé, Guy; Beard, D.; Beard, J. W.

1962-01-01

Thymus glands of chicks with leukemia induced by BAI strain A (myeloblastosis) virus were fixed in cold 4 per cent formaldehyde-sucrose. Frozen sections were incubated in the ATPase medium of Wachstein and Meisel and studied by light microscopy and electron microscopy. The ATPase activity of the virus is localized to the outermost membrane of the virus. The membrane of the blast-like cells of the thymus cortex from which the virus emerges, by budding, also possesses such activity. It appears likely that the outermost membrane of the virus is derived from the plasma membrane of these cells. PMID:13939125

Elemental X-ray mapping of agglutinated foraminifer tests: A non- destructive technique for determining compositional characteristics.

USGS Publications Warehouse

Commeau, R.F.; Reynolds, Leslie A.; Poag, C.W.

1985-01-01

The composition of agglutinated foraminiferal tests vary remarkably in response to local substrate characteristics, physiochemical properties of the water column and species- dependant selectivity of test components. We have employed a technique that combines a scanning electron microscope with an energy dispersive X-ray spectrometer system to identify major and minor elemental constituents of agglutinated foraminiferal walls. As a sample is bombarded with a beam of high energy electrons, X-rays are generated that are characteristic of the elements present. As a result, X- ray density maps can be produced for each of several elements present in the tests of agglutinated foraminifers. 

Localization effects in radiationally disordered high-temperature superconductors: Theoretical interpretation

NASA Technical Reports Server (NTRS)

Goshchitskii, B. N.; Davydov, S. A.; Karkin, A. E.; Mirmelstein, A. V.; Sadovskii, M. V.

1990-01-01

Theoretical interpretation of recent experiments on radiationally disordered high-temperature superconductors is presented, based on the concepts of mutual interplay of Anderson localization and superconductivity. Microscopic derivation of Ginzburg-Landau coefficients for the quasi-two-dimensional system in the vicinity of localization transition is given in the framework of the self-consistent theory of localization. The 'minimal metallic conductivity' for the quasi-two-dimensional case is enhanced due to a small overlap of electronic states on the nearest neighbor conducting planes. This leads to a stronger influence of localization effects than in ordinary (three-dimensional) superconductors. From this point of view even the initial samples of high-temperature superconductors are already very close to Anderson transition. Anomalies of H(c2) are also analyzed, explaining the upward curvature of H(c2)(T) and apparent independence of dH(c2)/dT (T = T(sub c)) on the degree of disorder as due to localization effects. Researchers discuss the possible reasons of fast T(sub c) degradation due to the enhanced Coulomb effects caused by the disorder induced decrease of localization length. The appearance and growth of localized magnetic moments is also discussed. The disorder dependence of localization length calculated from the experimental data on conductivity correlates reasonably with the theoretical criterion for suppression of superconductivity in the system with localized electronic states.

Purchase of a Transmission Electron Microscope for Xavier University of Louisiana

DTIC Science & Technology

2015-05-15

imaging facility on the second floor of the Pharmacy Addition at Xavier University that already includes two scanning electron microscopes. The new TEM...is now in use. Xavier University has formally pledged to provide funds for the 1. REPORT DATE (DD-MM-YYYY) 4. TITLE AND SUBTITLE 13. SUPPLEMENTARY...for Public Release; Distribution Unlimited Final Report: Purchase of a Transmission Electron Microscope for Xavier University of Louisiana The views

Direct observation of how the heavy-fermion state develops in CeCoIn5

NASA Astrophysics Data System (ADS)

Chen, Q. Y.; Xu, D. F.; Niu, X. H.; Jiang, J.; Peng, R.; Xu, H. C.; Wen, C. H. P.; Ding, Z. F.; Huang, K.; Shu, L.; Zhang, Y. J.; Lee, H.; Strocov, V. N.; Shi, M.; Bisti, F.; Schmitt, T.; Huang, Y. B.; Dudin, P.; Lai, X. C.; Kirchner, S.; Yuan, H. Q.; Feng, D. L.

2017-07-01

Heavy-fermion systems share some of the strange metal phenomenology seen in other unconventional superconductors, providing a unique opportunity to set strange metals in a broader context. Central to understanding heavy-fermion systems is the interplay of localization and itinerancy. These materials acquire high electronic masses and a concomitant Fermi volume increase as the f electrons delocalize at low temperatures. However, despite the wide-spread acceptance of this view, a direct microscopic verification has been lacking. Here we report high-resolution angle-resolved photoemission measurements on CeCoIn5, a prototypical heavy-fermion compound, which spectroscopically resolve the development of band hybridization and the Fermi surface expansion over a wide temperature region. Unexpectedly, the localized-to-itinerant transition occurs at surprisingly high temperatures, yet f electrons are still largely localized even at the lowest temperature. These findings point to an unanticipated role played by crystal-field excitations in the strange metal behavior of CeCoIn5. Our results offer a comprehensive experimental picture of the heavy-fermion formation, setting the stage for understanding the emergent properties, including unconventional superconductivity, in this and related materials.

Local band gap measurements by VEELS of thin film solar cells.

PubMed

Keller, Debora; Buecheler, Stephan; Reinhard, Patrick; Pianezzi, Fabian; Pohl, Darius; Surrey, Alexander; Rellinghaus, Bernd; Erni, Rolf; Tiwari, Ayodhya N

2014-08-01

This work presents a systematic study that evaluates the feasibility and reliability of local band gap measurements of Cu(In,Ga)Se2 thin films by valence electron energy-loss spectroscopy (VEELS). The compositional gradients across the Cu(In,Ga)Se2 layer cause variations in the band gap energy, which are experimentally determined using a monochromated scanning transmission electron microscope (STEM). The results reveal the expected band gap variation across the Cu(In,Ga)Se2 layer and therefore confirm the feasibility of local band gap measurements of Cu(In,Ga)Se2 by VEELS. The precision and accuracy of the results are discussed based on the analysis of individual error sources, which leads to the conclusion that the precision of our measurements is most limited by the acquisition reproducibility, if the signal-to-noise ratio of the spectrum is high enough. Furthermore, we simulate the impact of radiation losses on the measured band gap value and propose a thickness-dependent correction. In future work, localized band gap variations will be measured on a more localized length scale to investigate, e.g., the influence of chemical inhomogeneities and dopant accumulations at grain boundaries.

Diffuse Surface Scattering in the Plasmonic Resonances of Ultralow Electron Density Nanospheres.

PubMed

Monreal, R Carmina; Antosiewicz, Tomasz J; Apell, S Peter

2015-05-21

Localized surface plasmon resonances (LSPRs) have recently been identified in extremely diluted electron systems obtained by doping semiconductor quantum dots. Here, we investigate the role that different surface effects, namely, electronic spill-out and diffuse surface scattering, play in the optical properties of these ultralow electron density nanosystems. Diffuse scattering originates from imperfections or roughness at a microscopic scale on the surface. Using an electromagnetic theory that describes this mechanism in conjunction with a dielectric function including the quantum size effect, we find that the LSPRs show an oscillatory behavior in both position and width for large particles and a strong blue shift in energy and an increased width for smaller radii, consistent with recent experimental results for photodoped ZnO nanocrystals. We thus show that the commonly ignored process of diffuse surface scattering is a more important mechanism affecting the plasmonic properties of ultralow electron density nanoparticles than the spill-out effect.

Scanning electron microscopy of hepatic ultrastructure: secondary, backscattered, and transmitted electron imaging.

PubMed

Miyai, K; Abraham, J L; Linthicum, D S; Wagner, R M

1976-10-01

Several methods of tissue preparation and different modes of operation of the scanning electron microscope were used to study the ultrastructure of rat liver. Rat livers were perfusion fixed with buffered 2 per cent paraformaldehyde or a mixture of 1.5 per cent paraformaldehyde and 1 per cent glutaraldehyde and processed as follows. Tissue blocks were postfixed in buffered 2 per cent osmium tetroxide followed sequentially by the ligand-mediated osmium binding technique, dehydration and cryofracture in ethanol, and critical point drying. They were then examined without metal coating in the scanning electron microscope operating in the secondary electron and backscattered electron modes. Fifty-micrometer sections were cut with a tissue sectioner, stained with lead citrate, postfixed with osmium, dehydrated, critical point dried, and examined in the secondary electron and back-scattered electron modes. Frozen sections (0.25 to 0.75 mum. thick) were cut by the method of Tokuyasu (Toluyasu KT: J Cell Biol 57:551, 1973) and their scanning transmission electron microscope images were examined either with a scanning transmission electron microscope detector or with a conversion stub using the secondary electron detector. Secondary electron images of the liver prepared by ligand-mediated osmium binding and subsequent cryofracture revealed such intracellular structures as cisternae of the endoplasmic reticulum, lysosomes, mitochondria, lipid droplets, nucleolus and nuclear chromatin, as well as the usual surface morphology, Lipocytes in the perisinusoidal space were readily identified. Backscattered electron images. Unembedded frozen sections had little drying artifact and were virtually free of freezing damage. The scanning transmission electron microscope image revealed those organelles visualized by the secondary electron mode in the ligand-mediated osmium binding-treated tissue.

Optimized unconventional superconductivity in a molecular Jahn-Teller metal

PubMed Central

Zadik, Ruth H.; Takabayashi, Yasuhiro; Klupp, Gyöngyi; Colman, Ross H.; Ganin, Alexey Y.; Potočnik, Anton; Jeglič, Peter; Arčon, Denis; Matus, Péter; Kamarás, Katalin; Kasahara, Yuichi; Iwasa, Yoshihiro; Fitch, Andrew N.; Ohishi, Yasuo; Garbarino, Gaston; Kato, Kenichi; Rosseinsky, Matthew J.; Prassides, Kosmas

2015-01-01

Understanding the relationship between the superconducting, the neighboring insulating, and the normal metallic state above Tc is a major challenge for all unconventional superconductors. The molecular A3C60 fulleride superconductors have a parent antiferromagnetic insulator in common with the atom-based cuprates, but here, the C603– electronic structure controls the geometry and spin state of the structural building unit via the on-molecule Jahn-Teller effect. We identify the Jahn-Teller metal as a fluctuating microscopically heterogeneous coexistence of both localized Jahn-Teller–active and itinerant electrons that connects the insulating and superconducting states of fullerides. The balance between these molecular and extended lattice features of the electrons at the Fermi level gives a dome-shaped variation of Tc with interfulleride separation, demonstrating molecular electronic structure control of superconductivity. PMID:26601168

Electron Microscope Center Opens at Berkeley.

ERIC Educational Resources Information Center

Robinson, Arthur L.

1981-01-01

A 1.5-MeV High Voltage Electron Microscope has been installed at the Lawrence Berkeley Laboratory which will help materials scientists and biologists study samples in more true-to-life situations. A 1-MeV Atomic Resolution Microscope will be installed at the same location in two years which will allow scientists to distinguish atoms. (DS)

Specimen Holder for Analytical Electron Microscopes

NASA Technical Reports Server (NTRS)

Clanton, U. S.; Isaacs, A. M.; Mackinnon, I.

1985-01-01

Reduces spectral contamination by spurious X-ray. Specimen holder made of compressed carbon, securely retains standard electron microscope grid (disk) 3 mm in diameter and absorbs backscattered electrons that otherwise generate spurious X-rays. Since holder inexpensive, dedicated to single specimen when numerous samples examined.

Local sample thickness determination via scanning transmission electron microscopy defocus series.

PubMed

Beyer, A; Straubinger, R; Belz, J; Volz, K

2016-05-01

The usable aperture sizes in (scanning) transmission electron microscopy ((S)TEM) have significantly increased in the past decade due to the introduction of aberration correction. In parallel with the consequent increase of convergence angle the depth of focus has decreased severely and optical sectioning in the STEM became feasible. Here we apply STEM defocus series to derive the local sample thickness of a TEM sample. To this end experimental as well as simulated defocus series of thin Si foils were acquired. The systematic blurring of high resolution high angle annular dark field images is quantified by evaluating the standard deviation of the image intensity for each image of a defocus series. The derived dependencies exhibit a pronounced maximum at the optimum defocus and drop to a background value for higher or lower values. The full width half maximum (FWHM) of the curve is equal to the sample thickness above a minimum thickness given by the size of the used aperture and the chromatic aberration of the microscope. The thicknesses obtained from experimental defocus series applying the proposed method are in good agreement with the values derived from other established methods. The key advantages of this method compared to others are its high spatial resolution and that it does not involve any time consuming simulations. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

Topological dynamics of gyroscopic and Floquet lattices from Newton's laws

NASA Astrophysics Data System (ADS)

Lee, Ching Hua; Li, Guangjie; Jin, Guliuxin; Liu, Yuhan; Zhang, Xiao

2018-02-01

Despite intense interest in realizing topological phases across a variety of electronic, photonic, and mechanical platforms, the detailed microscopic origin of topological behavior often remains elusive. To bridge this conceptual gap, we show how hallmarks of topological modes—boundary localization and chirality—emerge from Newton's laws in mechanical topological systems. We first construct a gyroscopic lattice with analytically solvable edge modes, and show how the Lorentz and spring restoring forces conspire to support very robust "dangling bond" boundary modes. The chirality and locality of these modes intuitively emerges from microscopic balancing of restoring forces and cyclotron tendencies. Next, we introduce the highlight of this work, an experimentally realistic mechanical nonequilibrium (Floquet) Chern lattice driven by ac electromagnets. Through appropriate synchronization of the ac driving protocol, the Floquet lattice is "pushed around" by a rotating potential analogous to an object washed ashore by water waves. Besides hosting "dangling bond" chiral modes analogous to the gyroscopic boundary modes, our Floquet Chern lattice also supports peculiar half-period chiral modes with no static analog, i.e., analogs of anomalous Floquet Chern insulators edge modes. With key parameters controlled electronically, our setup has the advantage of being dynamically tunable for applications involving arbitrary Floquet modulations. The physical intuition gleaned from our two prototypical topological systems is applicable not just to arbitrarily complicated mechanical systems, but also photonic and electrical topological setups.

Field enhancement of electronic conductance at ferroelectric domain walls

DOE PAGES

Vasudevan, Rama K.; Cao, Ye; Laanait, Nouamane; ...

2017-11-06

Ferroelectric domain walls have continued to attract widespread attention due to both the novelty of the phenomena observed and the ability to reliably pattern them in nanoscale dimensions. But, the conductivity mechanisms remain in debate, particularly around nominally uncharged walls. Here, we posit a conduction mechanism relying on field-modification effect from polarization re-orientation and the structure of the reverse-domain nucleus. Through conductive atomic force microscopy measurements on an ultra-thin (001) BiFeO 3 thin film, in combination with phase-field simulations, we show that the field-induced twisted domain nucleus formed at domain walls results in local-field enhancement around the region of themore » atomic force microscope tip. In conjunction with slight barrier lowering, these two effects are sufficient to explain the observed emission current distribution. Our results suggest that different electronic properties at domain walls are not necessary to observe localized enhancement in domain wall currents.« less

Microscope and method of use

DOEpatents

Bongianni, Wayne L.

1984-01-01

A method and apparatus for electronically focusing and electronically scanning microscopic specimens are given. In the invention, visual images of even moving, living, opaque specimens can be acoustically obtained and viewed with virtually no time needed for processing (i.e., real time processing is used). And planar samples are not required. The specimens (if planar) need not be moved during scanning, although it will be desirable and possible to move or rotate nonplanar specimens (e.g., laser fusion targets) against the lens of the apparatus. No coupling fluid is needed, so specimens need not be wetted. A phase acoustic microscope is also made from the basic microscope components together with electronic mixers.

Simultaneous specimen and stage cleaning device for analytical electron microscope

DOEpatents

Zaluzec, Nestor J.

1996-01-01

An improved method and apparatus are provided for cleaning both a specimen stage, a specimen and an interior of an analytical electron microscope (AEM). The apparatus for cleaning a specimen stage and specimen comprising a plasma chamber for containing a gas plasma and an air lock coupled to the plasma chamber for permitting passage of the specimen stage and specimen into the plasma chamber and maintaining an airtight chamber. The specimen stage and specimen are subjected to a reactive plasma gas that is either DC or RF excited. The apparatus can be mounted on the analytical electron microscope (AEM) for cleaning the interior of the microscope.

Microscope and method of use

DOEpatents

Bongianni, W.L.

1984-04-17

A method and apparatus for electronically focusing and electronically scanning microscopic specimens are given. In the invention, visual images of even moving, living, opaque specimens can be acoustically obtained and viewed with virtually no time needed for processing (i.e., real time processing is used). And planar samples are not required. The specimens (if planar) need not be moved during scanning, although it will be desirable and possible to move or rotate nonplanar specimens (e.g., laser fusion targets) against the lens of the apparatus. No coupling fluid is needed, so specimens need not be wetted. A phase acoustic microscope is also made from the basic microscope components together with electronic mixers. 7 figs.

Development of a SEM-based low-energy in-line electron holography microscope for individual particle imaging.

PubMed

Adaniya, Hidehito; Cheung, Martin; Cassidy, Cathal; Yamashita, Masao; Shintake, Tsumoru

2018-05-01

A new SEM-based in-line electron holography microscope has been under development. The microscope utilizes conventional SEM and BF-STEM functionality to allow for rapid searching of the specimen of interest, seamless interchange between SEM, BF-STEM and holographic imaging modes, and makes use of coherent low-energy in-line electron holography to obtain low-dose, high-contrast images of light element materials. We report here an overview of the instrumentation and first experimental results on gold nano-particles and carbon nano-fibers for system performance tests. Reconstructed images obtained from the holographic imaging mode of the new microscope show substantial image contrast and resolution compared to those acquired by SEM and BF-STEM modes, demonstrating the feasibility of high-contrast imaging via low-energy in-line electron holography. The prospect of utilizing the new microscope to image purified biological specimens at the individual particle level is discussed and electron optical issues and challenges to further improve resolution and contrast are considered. Copyright © 2018 Elsevier B.V. All rights reserved.

Diffusion of low-energy electrons in tissue-like liquids.

PubMed

Malamut, C; Paes-Leme, P J; Paschoa, A S

1992-11-01

The spatial-energetic distribution of low-energy electrons was studied for a source located in a liquid medium simulating biological tissue. A time-independent Boltzmann equation was used to model this distribution microscopically. Ionization was treated as a perturbation to a quasi-elastic collision process between the electron and the medium. A diffusion limit was obtained by using a scale parameter, leading to a sequence of recursive partial differential equations whose solutions, associated with a macroscopic scale, were obtained by numerical approximations. As an application, electron ranges were estimated based on these solutions and then compared with values reported in the open literature based on experimental results and on Monte Carlo calculation. Local dosimetry, i.e., the energy imparted to a volume of a sphere with radius equal to the range of low-energy electrons, of low-energy electrons from internal emitters can benefit by the knowledge of the ranges estimated for biological tissue. Auger electron emitters, for example, have been the object of a number of investigations because of their radiobiological significance.

75 FR 43918 - National Center for Toxicological Research, et al.; Notice of Consolidated Decision on...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-07-27

... Research, et al.; Notice of Consolidated Decision on Applications for Duty-Free Entry of Electron...: National Center for Toxicological Research, (USFDA), Jefferson, AK 72079. Instrument: Electron Microscope.... Applicant: University of Virginia, Charlottesville, VA 22903. Instrument: Electron Microscope. Manufacturer...

A versatile LabVIEW and field-programmable gate array-based scanning probe microscope for in operando electronic device characterization.

PubMed

Berger, Andrew J; Page, Michael R; Jacob, Jan; Young, Justin R; Lewis, Jim; Wenzel, Lothar; Bhallamudi, Vidya P; Johnston-Halperin, Ezekiel; Pelekhov, Denis V; Hammel, P Chris

2014-12-01

Understanding the complex properties of electronic and spintronic devices at the micro- and nano-scale is a topic of intense current interest as it becomes increasingly important for scientific progress and technological applications. In operando characterization of such devices by scanning probe techniques is particularly well-suited for the microscopic study of these properties. We have developed a scanning probe microscope (SPM) which is capable of both standard force imaging (atomic, magnetic, electrostatic) and simultaneous electrical transport measurements. We utilize flexible and inexpensive FPGA (field-programmable gate array) hardware and a custom software framework developed in National Instrument's LabVIEW environment to perform the various aspects of microscope operation and device measurement. The FPGA-based approach enables sensitive, real-time cantilever frequency-shift detection. Using this system, we demonstrate electrostatic force microscopy of an electrically biased graphene field-effect transistor device. The combination of SPM and electrical transport also enables imaging of the transport response to a localized perturbation provided by the scanned cantilever tip. Facilitated by the broad presence of LabVIEW in the experimental sciences and the openness of our software solution, our system permits a wide variety of combined scanning and transport measurements by providing standardized interfaces and flexible access to all aspects of a measurement (input and output signals, and processed data). Our system also enables precise control of timing (synchronization of scanning and transport operations) and implementation of sophisticated feedback protocols, and thus should be broadly interesting and useful to practitioners in the field.

A versatile LabVIEW and field-programmable gate array-based scanning probe microscope for in operando electronic device characterization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berger, Andrew J., E-mail: berger.156@osu.edu; Page, Michael R.; Young, Justin R.

Understanding the complex properties of electronic and spintronic devices at the micro- and nano-scale is a topic of intense current interest as it becomes increasingly important for scientific progress and technological applications. In operando characterization of such devices by scanning probe techniques is particularly well-suited for the microscopic study of these properties. We have developed a scanning probe microscope (SPM) which is capable of both standard force imaging (atomic, magnetic, electrostatic) and simultaneous electrical transport measurements. We utilize flexible and inexpensive FPGA (field-programmable gate array) hardware and a custom software framework developed in National Instrument's LabVIEW environment to perform themore » various aspects of microscope operation and device measurement. The FPGA-based approach enables sensitive, real-time cantilever frequency-shift detection. Using this system, we demonstrate electrostatic force microscopy of an electrically biased graphene field-effect transistor device. The combination of SPM and electrical transport also enables imaging of the transport response to a localized perturbation provided by the scanned cantilever tip. Facilitated by the broad presence of LabVIEW in the experimental sciences and the openness of our software solution, our system permits a wide variety of combined scanning and transport measurements by providing standardized interfaces and flexible access to all aspects of a measurement (input and output signals, and processed data). Our system also enables precise control of timing (synchronization of scanning and transport operations) and implementation of sophisticated feedback protocols, and thus should be broadly interesting and useful to practitioners in the field.« less

Glutamate and GABA receptors and transporters in the basal ganglia: What does their subsynaptic localization reveal about their function?

PubMed Central

Galvan, Adriana; Kuwajima, Masaaki; Smith, Yoland

2006-01-01

GABA and glutamate, the main transmitters in the basal ganglia, exert their effects through ionotropic and metabotropic receptors. The dynamic activation of these receptors in response to released neurotransmitter depends, among other factors, on their precise localization in relation to corresponding synapses. The use of high resolution quantitative electron microscope immunocytochemical techniques has provided in-depth description of the subcellular and subsynaptic localization of these receptors in the CNS. In this article, we review recent findings on the ultrastructural localization of GABA and glutamate receptors and transporters in the basal ganglia, at synaptic, extrasynaptic and presynaptic sites. The anatomical evidence supports numerous potential locations for receptor-neurotransmitter interactions, and raises important questions regarding mechanisms of activation and function of synaptic versus extrasynaptic receptors in the basal ganglia. PMID:17059868

Scanning Electron Microscope Observations of Marine Microorganisms on Surfaces Coated with Antifouling Paints.

DTIC Science & Technology

1981-06-01

sessile marine inverte- brates in Monterey harbor. Veliger 17 (supplement): 1-35. 1977. The nature of primary organic films in the marine environment and...I A10A4h 605 NAVAL POSTGRADUATE SCHOOL MONTEREY CA F/S 11/3 SCANING ELECTRON MICROSCOPE OBSERVATIONS OF MARINE MICROORANI-E-C(U) UNLSSIFIED N*2...Scanning Electron Microscope Observations Master’s thesis; of Marine Microorganisms on Surfaces June 1981 Coated with Ant ifouling Paints 6.PERFORMING

Electron microscope aperture system

NASA Technical Reports Server (NTRS)

Heinemann, K. (Inventor)

1976-01-01

An electron microscope including an electron source, a condenser lens having either a circular aperture for focusing a solid cone of electrons onto a specimen or an annular aperture for focusing a hollow cone of electrons onto the specimen, and an objective lens having an annular objective aperture, for focusing electrons passing through the specimen onto an image plane are described. The invention also entails a method of making the annular objective aperture using electron imaging, electrolytic deposition and ion etching techniques.

Choice and maintenance of equipment for electron crystallography.

PubMed

Mills, Deryck J; Vonck, Janet

2013-01-01

The choice of equipment for an electron crystallography laboratory will ultimately be determined by the available budget; nevertheless, the ideal lab will have two electron microscopes: a dedicated 300 kV cryo-EM with a field emission gun and a smaller LaB(6) machine for screening. The high-end machine should be equipped with photographic film or a very large CCD or CMOS camera for 2D crystal data collection; the screening microscope needs a mid-size CCD for rapid evaluation of crystal samples. The microscope room installations should provide adequate space and a special environment that puts no restrictions on the collection of high-resolution data. Equipment for specimen preparation includes a carbon coater, glow discharge unit, light microscope, plunge freezer, and liquid nitrogen containers and storage dewars. When photographic film is to be used, additional requirements are a film desiccator, dark room, optical diffractometer, and a film scanner. Having the electron microscopes and ancillary equipment well maintained and always in optimum condition facilitates the production of high-quality data.

Vibrational spectroscopy in the electron microscope.

PubMed

Krivanek, Ondrej L; Lovejoy, Tracy C; Dellby, Niklas; Aoki, Toshihiro; Carpenter, R W; Rez, Peter; Soignard, Emmanuel; Zhu, Jiangtao; Batson, Philip E; Lagos, Maureen J; Egerton, Ray F; Crozier, Peter A

2014-10-09

Vibrational spectroscopies using infrared radiation, Raman scattering, neutrons, low-energy electrons and inelastic electron tunnelling are powerful techniques that can analyse bonding arrangements, identify chemical compounds and probe many other important properties of materials. The spatial resolution of these spectroscopies is typically one micrometre or more, although it can reach a few tens of nanometres or even a few ångströms when enhanced by the presence of a sharp metallic tip. If vibrational spectroscopy could be combined with the spatial resolution and flexibility of the transmission electron microscope, it would open up the study of vibrational modes in many different types of nanostructures. Unfortunately, the energy resolution of electron energy loss spectroscopy performed in the electron microscope has until now been too poor to allow such a combination. Recent developments that have improved the attainable energy resolution of electron energy loss spectroscopy in a scanning transmission electron microscope to around ten millielectronvolts now allow vibrational spectroscopy to be carried out in the electron microscope. Here we describe the innovations responsible for the progress, and present examples of applications in inorganic and organic materials, including the detection of hydrogen. We also demonstrate that the vibrational signal has both high- and low-spatial-resolution components, that the first component can be used to map vibrational features at nanometre-level resolution, and that the second component can be used for analysis carried out with the beam positioned just outside the sample--that is, for 'aloof' spectroscopy that largely avoids radiation damage.

Investigation of abrupt degradation of drain current caused by under-gate crack in AlGaN/GaN high electron mobility transistors during high temperature operation stress

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zeng, Chang; Liao, XueYang; Li, RuGuan

2015-09-28

In this paper, we investigate the degradation mode and mechanism of AlGaN/GaN based high electron mobility transistors (HEMTs) during high temperature operation (HTO) stress. It demonstrates that there was abrupt degradation mode of drain current during HTO stress. The abrupt degradation is ascribed to the formation of crack under the gate which was the result of the brittle fracture of epilayer based on failure analysis. The origin of the mechanical damage under the gate is further investigated and discussed based on top-down scanning electron microscope, cross section transmission electron microscope and energy dispersive x-ray spectroscopy analysis, and stress simulation. Basedmore » on the coupled analysis of the failure physical feature and stress simulation considering the coefficient of thermal expansion (CTE) mismatch in different materials in gate metals/semiconductor system, the mechanical damage under the gate is related to mechanical stress induced by CTE mismatch in Au/Ti/Mo/GaN system and stress concentration caused by the localized structural damage at the drain side of the gate edge. These results indicate that mechanical stress induced by CTE mismatch of materials inside the device plays great important role on the reliability of AlGaN/GaN HEMTs during HTO stress.« less

Ultrastructural Study of Some Pollen Grains of Prairie Flowers

ERIC Educational Resources Information Center

Kozar, Frank

1973-01-01

Discusses the importance of the electron microscope, and in particular the scanning electron microscope, in studying the surface topography, sectional substructures, and patterns of development of pollen grains. The production, dispersal methods, and structure of pollen grains are described and illustrated with numerous electron micrographs. (JR)

Synthesis Properties and Electron Spin Resonance Properties of Titanic Materials (abstract)

NASA Astrophysics Data System (ADS)

Cho, Jung Min; Lee, Jun; Kim, Tak Hee; Sun, Min Ho; Jang, Young Bae; Cho, Sung June

2009-04-01

Titanic materials were synthesized by hydrothermal method of TiO2 anatase in 10M LiOH, 10M NaOH, and 14M KOH at 130° C for 30 hours. Alkaline media were removed from the synthesized products using 0.1N HCl aqueous solution. The as-prepared samples were characterized by scanning electron microscope, transmission electron microscope, X-ray diffraction, Brunauer-Emmett-Teller isotherm, and electron spin resonance. Different shapes of synthesized products were observed through the typical electron microscope and indicated that the formation of the different morphologies depends on the treatment conditions of highly alkaline media. Many micropores were observed in the cubic or octahedral type of TiO2 samples through the typical electron microscope and Langmuir adsorption-desorption isotherm of liquid nitrogen at 77° K. Electron spin resonance studies have also been carried out to verify the existence of paramagnetic sites such as oxygen vacancies on the titania samples. The effect of alkali metal ions on the morphologies and physicochemical properties of nanoscale titania are discussed.

Design and performance of a beetle-type double-tip scanning tunneling microscope

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jaschinsky, Philipp; Coenen, Peter; Pirug, Gerhard

2006-09-15

A combination of a double-tip scanning tunneling microscope with a scanning electron microscope in ultrahigh vacuum environment is presented. The compact beetle-type design made it possible to integrate two independently driven scanning tunneling microscopes in a small space. Moreover, an additional level for coarse movement allows the decoupling of the translation and approach of the tunneling tip. The position of the two tips can be controlled from the millimeter scale down to 50 nm with the help of an add-on electron microscope. The instrument is capable of atomic resolution imaging with each tip.

The trapping and distribution of charge in polarized polymethylmethacrylate under electron-beam irradiation

NASA Astrophysics Data System (ADS)

Song, Z. G.; Gong, H.; Ong, C. K.

1997-06-01

A scanning electron microscope (SEM) mirror-image method (MIM) is employed to investigate the charging behaviour of polarized polymethylmethacrylate (PMMA) under electron-beam irradiation. An ellipsoid is used to model the trapped charge distribution and a fitting method is employed to calculate the total amount of the trapped charge and its distribution parameters. The experimental results reveal that the charging ability decreases with increasing applied electric field, which polarizes the PMMA sample, whereas the trapped charge distribution is elongated along the direction of the applied electric field and increases with increasing applied electric field. The charges are believed to be trapped in some localization states, of activation energy and radius estimated to be about 19.6 meV and 0022-3727/30/11/004/img6, respectively.

Development of Scanning Ultrafast Electron Microscope Capability.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Collins, Kimberlee Chiyoko; Talin, Albert Alec; Chandler, David W.

Modern semiconductor devices rely on the transport of minority charge carriers. Direct examination of minority carrier lifetimes in real devices with nanometer-scale features requires a measurement method with simultaneously high spatial and temporal resolutions. Achieving nanometer spatial resolutions at sub-nanosecond temporal resolution is possible with pump-probe methods that utilize electrons as probes. Recently, a stroboscopic scanning electron microscope was developed at Caltech, and used to study carrier transport across a Si p-n junction [ 1 , 2 , 3 ] . In this report, we detail our development of a prototype scanning ultrafast electron microscope system at Sandia National Laboratoriesmore » based on the original Caltech design. This effort represents Sandia's first exploration into ultrafast electron microscopy.« less

Enantioselectively controlled release of chiral drug (metoprolol) using chiral mesoporous silica materials

NASA Astrophysics Data System (ADS)

Guo, Zhen; Du, Yu; Liu, Xianbin; Ng, Siu-Choon; Chen, Yuan; Yang, Yanhui

2010-04-01

Chiral porous materials have attracted burgeoning attention on account of their potential applications in many areas, such as enantioseparation, chiral catalysis, chemical sensors and drug delivery. In this report, chiral mesoporous silica (CMS) materials with various pore sizes and structures were prepared using conventional achiral templates (other than chiral surfactant) and a chiral cobalt complex as co-template. The synthesized CMS materials were characterized by x-ray diffraction, nitrogen physisorption, scanning electron microscope and transmission electron microscope. These CMS materials, as carriers, were demonstrated to be able to control the enantioselective release of a representative chiral drug (metoprolol). The release kinetics, as modeled by the power law equation, suggested that the release profiles of metoprolol were remarkably dependent on the pore diameter and pore structure of CMS materials. More importantly, R- and S-enantiomers of metoprolol exhibited different release kinetics on CMS compared to the corresponding achiral mesoporous silica (ACMS), attributable to the existence of local chirality on the pore wall surface of CMS materials. The chirality of CMS materials on a molecular level was further substantiated by vibrational circular dichroism measurements.

Studying dynamic processes in liquids by TEM/STEM/DTEM

NASA Astrophysics Data System (ADS)

Abellan, Patricia; Evans, James; Woehl, Taylor; Jungjohann, Katherine; Parent, Lucas; Arslan, Ilke; Ristenpart, William; Browning, Nigel; Mater. Sci. Group Team; Microsc. Group Team; Catal. Sci. Group Collaboration; Ristenpart Res. Group Collaboration

2013-03-01

In order to study dynamic phenomena such as corrosion or catalysis, extreme environmental conditions must be reproduced around the specimen - these include high-temperatures, high-pressures, specific oxidizing/reducing atmospheres or a liquid environment. The use of environmental stages specifically designed to fit in any transmission electron microscope (TEM) allows us to apply the distinct capabilities of each instrument to study dynamic processes. Localized gas/fluid conditions are created around the sample and separated from the high vacuum inside the microscope using hermetically sealed windowed-cells. Advanced capabilities of these techniques include spatial resolutions of ~1 Angstrom or better in aberration corrected instruments or temporal resolutions in the microsecond-nanosecond range in a dynamic TEM (DTEM). Here, unique qualities of the DTEM that benefit the in-situ experiments with gas/fluid environmental cells will be discussed. We also present our results with a liquid stage allowing atomic resolution imaging of nanomaterials in a colloidal suspension, core EEL spectra acquisition, continuous flow, controlled growth of nanocrystals and systematic calibration of the effect of the electron dose on silver nuclei formation.

The microscopic structure of charge density waves in underdoped YBa 2Cu 3O 6.54 revealed by x-ray diffraction

DOE PAGES

E. M. Forgan; Huecker, M.; Blackburn, E.; ...

2015-12-09

Charge density wave (CDW) order appears throughout the underdoped high-temperature cuprate superconductors, but the underlying symmetry breaking and the origin of the CDW remain unclear. We use X-ray diffraction to determine the microscopic structure of the CDWs in an archetypical cuprate YBa 2Cu 3O 6.54 at its superconducting transition temperature ~60 K. We find that the CDWs in this material break the mirror symmetry of the CuO 2 bilayers. The ionic displacements in the CDWs have two components, which are perpendicular and parallel to the CuO 2 planes, and are out of phase with each other. The planar oxygen atomsmore » have the largest displacements, perpendicular to the CuO 2 planes. Our results allow many electronic properties of the underdoped cuprates to be understood. For example, the CDWs will lead to local variations in the electronic structure, giving an explicit explanation of density-wave states with broken symmetry observed in scanning tunnelling microscopy and soft X-ray measurements.« less

The microscopic structure of charge density waves in underdoped YBa2Cu3O6.54 revealed by X-ray diffraction

NASA Astrophysics Data System (ADS)

Forgan, E. M.; Blackburn, E.; Holmes, A. T.; Briffa, A. K. R.; Chang, J.; Bouchenoire, L.; Brown, S. D.; Liang, Ruixing; Bonn, D.; Hardy, W. N.; Christensen, N. B.; Zimmermann, M. V.; Hücker, M.; Hayden, S. M.

2015-12-01

Charge density wave (CDW) order appears throughout the underdoped high-temperature cuprate superconductors, but the underlying symmetry breaking and the origin of the CDW remain unclear. We use X-ray diffraction to determine the microscopic structure of the CDWs in an archetypical cuprate YBa2Cu3O6.54 at its superconducting transition temperature ~60 K. We find that the CDWs in this material break the mirror symmetry of the CuO2 bilayers. The ionic displacements in the CDWs have two components, which are perpendicular and parallel to the CuO2 planes, and are out of phase with each other. The planar oxygen atoms have the largest displacements, perpendicular to the CuO2 planes. Our results allow many electronic properties of the underdoped cuprates to be understood. For instance, the CDWs will lead to local variations in the electronic structure, giving an explicit explanation of density-wave states with broken symmetry observed in scanning tunnelling microscopy and soft X-ray measurements.

Ultrastructure of cholinergic neurons in the laterodorsal tegmental nucleus of the rat: interaction with catecholamine fibers.

PubMed

Kubota, Y; Leung, E; Vincent, S R

1992-01-01

The ultrastructure of choline acetyltransferase (ChAT)-immunoreactive neurons in the laterodorsal tegmental nucleus (TLD) of the rat was investigated by immunohistochemical techniques. The immunoreactive neurons were medium to large in size, with a few elongated dendrites, contained well-developed cytoplasm, and a nucleus with deep infoldings. They received many nonimmunoreactive, mostly asymmetric synaptic inputs on their soma and dendrites. ChAT-immunoreactive, usually myelinated, axons were occasionally seen in TLD. Only one immunoreactive axon terminal was observed within TLD, and it made synaptic contact with a nonimmunoreactive neuronal perikaryon. The synaptic interactions between ChAT-immunoreactive neurons and tyrosine hydroxylase (TH)-immunoreactive fibers in the TLD were investigated with a double immunohistochemical staining method. ChAT-immunoreactivity detected with a beta-galactosidase method was light blue-green in the light microscope and formed dot-like electron dense particles at the electron microscopic level. TH-immunoreactivity, visualized with a nickel-enhanced immunoperoxidase method, was dark blue-black in the light microscope and diffusely opaque in the electron microscope. Therefore, the difference between these two kinds of immunoreactivity could be quite easily distinguished at both light and electron microscopic levels. In the light microscope, TH-positive fibers were often closely apposed to ChAT-immunoreactive cell bodies and dendrites in TLD. In the electron microscope, the cell soma and proximal dendrites of ChAT-immunoreactive neurons received synaptic contacts from TH-immunoreactive axon terminals. These results provide a morphological basis for catecholaminergic regulation of the cholinergic reticular system.

Microscopic droplet formation and energy transport analysis of condensation on scalable superhydrophobic nanostructured copper oxide surfaces.

PubMed

Li, GuanQiu; Alhosani, Mohamed H; Yuan, ShaoJun; Liu, HaoRan; Ghaferi, Amal Al; Zhang, TieJun

2014-12-09

Utilization of nanotechnologies in condensation has been recognized as one opportunity to improve the efficiency of large-scale thermal power and desalination systems. High-performance and stable dropwise condensation in widely-used copper heat exchangers is appealing for energy and water industries. In this work, a scalable and low-cost nanofabrication approach was developed to fabricate superhydrophobic copper oxide (CuO) nanoneedle surfaces to promote dropwise condensation and even jumping-droplet condensation. By conducting systematic surface characterization and in situ environmental scanning electron microscope (ESEM) condensation experiments, we were able to probe the microscopic formation physics of droplets on irregular nanostructured surfaces. At the early stages of condensation process, the interfacial surface tensions at the edge of CuO nanoneedles were found to influence both the local energy barriers for microdroplet growth and the advancing contact angles when droplets undergo depinning. Local surface roughness also has a significant impact on the volume of the condensate within the nanostructures and overall heat transfer from the vapor to substrate. Both our theoretical analysis and in situ ESEM experiments have revealed that the liquid condensate within the nanostructures determines the amount of the work of adhesion and kinetic energy associated with droplet coalescence and jumping. Local and global droplet growth models were also proposed to predict how the microdroplet morphology within nanostructures affects the heat transfer performance of early-stage condensation. Our quantitative analysis of microdroplet formation and growth within irregular nanostructures provides the insight to guide the anodization-based nanofabrication for enhancing dropwise and jumping-droplet condensation performance.

77 FR 71776 - Ohio University, et al.; Notice of Consolidated Decision on Applications for Duty-Free Entry of...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-12-04

... Consolidated Decision on Applications for Duty-Free Entry of Electron Microscope This is a decision... Stocker Center, Athens, OH 45701. Instrument: Electron Microscope. Manufacturer: JEOL Ltd., Japan... North Carolina Wilmington, 601 South College Road, Wilmington, NC 28403-5915. Instrument: Electron...

Influence of mechanical noise inside a scanning electron microscope.

PubMed

de Faria, Marcelo Gaudenzi; Haddab, Yassine; Le Gorrec, Yann; Lutz, Philippe

2015-04-01

The scanning electron microscope is becoming a popular tool to perform tasks that require positioning, manipulation, characterization, and assembly of micro-components. However, some of these applications require a higher level of performance with respect to dynamics and precision of positioning. One limiting factor is the presence of unidentified noises and disturbances. This work aims to study the influence of mechanical disturbances generated by the environment and by the microscope, identifying how these can affect elements in the vacuum chamber. To achieve this objective, a dedicated setup, including a high-resolution vibrometer, was built inside the microscope. This work led to the identification and quantification of main disturbances and noise sources acting on a scanning electron microscope. Furthermore, the effects of external acoustic excitations were analysed. Potential applications of these results include noise compensation and real-time control for high accuracy tasks.

Microcircuit testing and fabrication, using scanning electron microscopes

NASA Technical Reports Server (NTRS)

Nicolas, D. P.

1975-01-01

Scanning electron microscopes are used to determine both user-induced damages and manufacturing defects subtle enough to be missed by conventional light microscopy. Method offers greater depth of field and increased working distances.

Method of forming aperture plate for electron microscope

NASA Technical Reports Server (NTRS)

Heinemann, K. (Inventor)

1974-01-01

An electron microscope is described with an electron source a condenser lens having either a circular aperture for focusing a solid cone of electrons onto a specimen or an annular aperture for focusing a hollow cone of electrons onto the specimen. It also has objective lens with an annular objective aperture, for focusing electrons passing through the specimen onto an image plane. A method of making the annular objective aperture using electron imaging, electrolytic deposition and ion etching techniques is included.

Development of scanning electron and x-ray microscope

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matsumura, Tomokazu, E-mail: tomokzau.matsumura@etd.hpk.co.jp; Hirano, Tomohiko, E-mail: tomohiko.hirano@etd.hpk.co.jp; Suyama, Motohiro, E-mail: suyama@etd.hpk.co.jp

We have developed a new type of microscope possessing a unique feature of observing both scanning electron and X-ray images under one unit. Unlike former X-ray microscopes using SEM [1, 2], this scanning electron and X-ray (SELX) microscope has a sample in vacuum, thus it enables one to observe a surface structure of a sample by SEM mode, to search the region of interest, and to observe an X-ray image which transmits the region. For the X-ray observation, we have been focusing on the soft X-ray region from 280 eV to 3 keV to observe some bio samples and softmore » materials. The resolutions of SEM and X-ray modes are 50 nm and 100 nm, respectively, at the electron energy of 7 keV.« less

Examination of Surveyor 3 parts with the scanning electron microscope and electron microprobe

NASA Technical Reports Server (NTRS)

Chodos, A. A.; Devaney, J. R.; Evens, K. C.

1972-01-01

Two screws and two washers, several small chips of tubing, and a fiber removed from a third screw were examined with the scanning electron microscope and the electron microprobe. The purpose of the examination was to determine the nature of the material on the surface of these samples and to search for the presence of meteoritic material.

Immunofluorescent localization of Staphylococcos aureus antigen in acute bacterial endocarditis nephritis.

PubMed

Yum, M; Wheat, L J; Maxwell, D; Edwards, J L

1978-11-01

A 75-year-old man with Staphylococcus aureus endocarditis in whom acute diffuse proliferative glomerulonephritis developed is described. The light- and electron-microscopic changes of the glomeruli in this case were identical to those of acute poststreptococcal glomerulonephritis. Immunofluorescence revealed deposition of immunoglobulins and complement in the glomeruli. In addition, bacterial antigenic material was demonstrated in the glomeruli by indirect immunofluorescence. These observations further support the hypothesis of an immune-complex pathogenesis in this form of glomerulonephritis.

Immunocytochemical localization of glial fibrillary acidic protein (GFAP) in the area postrema of the cat - Light and electron microscopic study

NASA Technical Reports Server (NTRS)

Damelio, F. E.; Gibbs, M. A.; Mehler, W. R.; Eng, L. F.

1985-01-01

Glial fibrillary acidic protein (GFAP) was demonstrated in the cytoplasm and processes of ependymal cells and astroglial components of the area postrema of the cat. These observations differ from the findings in the ependyma of the ventricular cavities which are consistently negative for the protein. Since some studies have suggested sensory functions of the glial cells in this emetic chemoreceptor trigger zone, a careful consideration of morphological and biochemical attributes of these cells seems appropriate.

Ballistic transport in graphene grown by chemical vapor deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Calado, V. E.; Goswami, S.; Xu, Q.

2014-01-13

In this letter, we report the observation of ballistic transport on micron length scales in graphene synthesised by chemical vapour deposition (CVD). Transport measurements were done on Hall bar geometries in a liquid He cryostat. Using non-local measurements, we show that electrons can be ballistically directed by a magnetic field (transverse magnetic focussing) over length scales of ∼1 μm. Comparison with atomic force microscope measurements suggests a correlation between the absence of wrinkles and the presence of ballistic transport in CVD graphene.

Tunable Orbital-Selective Magnetic Interaction in Tricolor Oxide Interfaces

NASA Astrophysics Data System (ADS)

Cao, Yanwei; Kareev, Michael; Liu, Xiaoran; Choudhury, Debraj; Middey, Srimanta; Meyers, Derek; Chakhalian, Jak

2015-03-01

Recently, several theoretical scenarios of orbital-selective magnetic interactions were proposed to understand the emergence of the unexpected interfacial magnetism in the archetypical SrTiO3-based two-dimensional electron gas systems, the origin of which is still intriguing and not an entirely understood phenomenon in oxide interface physics. Experimentally, however, there thus far lacks a material system to directly demonstrate the magnetic interaction with orbital-selection (dxy vs. dxz/dyz) and eventually manipulate this magnetic interaction. To address this, here we induced 2DEG and localized magnetism into the same SrTiO3 layer by devising the heterostructure LaTiO3/SrTiO3/YTiO3. Combined electrical transport and atomic-resolved scanning transmission electron microscope with electron energy loss spectroscopy revealed that the magnetic localized electrons are formed by the spin transfer from the YTiO3 layer into 2DEG formed at the LaTiO3 /SrTiO3 interface, with the orbital occupancy and strength of the magnetic interaction controlled by the SrTiO3 layer thickness. Our work provides an ideal platform to explore the orbital physics driven by the interfacial magnetism with prospects for exciting spintronic applications.

Electron Energy Loss Spectroscopy imaging of surface plasmons at the nanometer scale.

PubMed

Colliex, Christian; Kociak, Mathieu; Stéphan, Odile

2016-03-01

Since their first realization, electron microscopes have demonstrated their unique ability to map with highest spatial resolution (sub-atomic in most recent instruments) the position of atoms as a consequence of the strong scattering of the incident high energy electrons by the nuclei of the material under investigation. When interacting with the electron clouds either on atomic orbitals or delocalized over the specimen, the associated energy transfer, measured and analyzed as an energy loss (Electron Energy Loss Spectroscopy) gives access to analytical properties (atom identification, electron states symmetry and localization). In the moderate energy-loss domain (corresponding to an optical spectral domain from the infrared (IR) to the rather far ultra violet (UV), EELS spectra exhibit characteristic collective excitations of the rather-free electron gas, known as plasmons. Boundary conditions, such as surfaces and/or interfaces between metallic and dielectric media, generate localized surface charge oscillations, surface plasmons (SP), which are associated with confined electric fields. This domain of research has been extraordinarily revived over the past few years as a consequence of the burst of interest for structures and devices guiding, enhancing and controlling light at the sub-wavelength scale. The present review focuses on the study of these surface plasmons with an electron microscopy-based approach which associates spectroscopy and mapping at the level of a single and well-defined nano-object, typically at the nanometer scale i.e. much improved with respect to standard, and even near-field, optical techniques. After calling to mind some early studies, we will briefly mention a few basic aspects of the required instrumentation and associated theoretical tools to interpret the very rich data sets recorded with the latest generation of (Scanning)TEM microscopes. The following paragraphs will review in more detail the results obtained on simple planar and spherical surfaces (or interfaces), extending then to more complex geometries isolated and in interaction, thus establishing basic rules from the classical to the quantum domain. A few hints towards application domains and prospective fields rich of interest will finally be indicated, confirming the demonstrated key role of electron-beam nanoplasmonics, the more as an yet-enhanced energy resolution down to the 10meV comes on the verge of current access. Copyright © 2015 Elsevier B.V. All rights reserved.

Electron transport in stepped Bi2Se3 thin films

NASA Astrophysics Data System (ADS)

Bauer, S.; Bobisch, C. A.

2017-08-01

We analyse the electron transport in a 16 quintuple layer thick stepped Bi2Se3 film grown on Si(1 1 1) by means of scanning tunnelling potentiometry (STP) and multi-point probe measurements. Scanning tunnelling microscopy images reveal that the local structure of the Bi2Se3 film is dominated by terrace steps and domain boundaries. From a microscopic study on the nm scale by STP, we find a mostly linear gradient of the voltage on the Bi2Se3 terraces which is interrupted by voltage drops at the position of the domain boundaries. The voltage drops indicate that the domain boundaries are scatterers for the electron transport. Macroscopic resistance measurements (2PP and in-line 4PP measurement) on the µm scale support the microscopic results. An additional rotational square 4PP measurement shows an electrical anisotropy of the sheet conductance parallel and perpendicular to the Bi2Se3 steps of about 10%. This is a result of the anisotropic step distribution at the stepped Bi2Se3 surface while domain boundaries are distributed isotropically. The determined value of the conductivity of the Bi2Se3 steps of about 1000 S cm-1 verifies the value of an earlier STP study.

A possible closure relation for heat transport in the solar wind

NASA Technical Reports Server (NTRS)

Feldman, W. C.; Asbridge, J. R.; Bame, S. J.; Gosling, J. T.; Lemons, D. S.

1979-01-01

The objective of the present paper is to search for an empirical closure relation for solar wind heat transport that applies to a microscopic scale. This task is approached by using the quasi-linear wave-particle formalism proposed by Perkins (1973) as a guide to derive an equation relating the relative drift speed between core-electron and proton populations to local bulk flow conditions. The resulting relationship, containing one free parameter, is found to provide a good characterization of Los Alamos Imp electron data measuring during the period from March 1971 through August 1974. An empirical closure relation is implied by this result because of the observed proportionality between heat flux and relative drift speed.

From Single Atoms to Nanoparticles — Spectroscopy on the Atomic Level

NASA Astrophysics Data System (ADS)

Nilius, Niklas

2003-12-01

The scanning tunneling microscope is not only a well-established tool for a topographic characterization of the sample surface on the atomic scale. It also provides a variety of spectroscopic techniques to examine electronic, magnetic, vibrational and optical properties of a localized system. The following presentation gives an overview, how scanning tunneling spectroscopy, inelastic electron tunneling spectroscopy and photon emission spectroscopy with the STM can be employed to investigate spatially confined metal systems and their interaction with molecular gases. The experiments were performed on single Pd and Au atoms, mono-atomic chains and individual Ag clusters on a NiAl support and a Al2O3 thin film.

Multi-pass transmission electron microscopy

DOE PAGES

Juffmann, Thomas; Koppell, Stewart A.; Klopfer, Brannon B.; ...

2017-05-10

Feynman once asked physicists to build better electron microscopes to be able to watch biology at work. While electron microscopes can now provide atomic resolution, electron beam induced specimen damage precludes high resolution imaging of sensitive materials, such as single proteins or polymers. Here, we use simulations to show that an electron microscope based on a multi-pass measurement protocol enables imaging of single proteins, without averaging structures over multiple images. While we demonstrate the method for particular imaging targets, the approach is broadly applicable and is expected to improve resolution and sensitivity for a range of electron microscopy imaging modalities,more » including, for example, scanning and spectroscopic techniques. The approach implements a quantum mechanically optimal strategy which under idealized conditions can be considered interaction-free.« less

Atomic electron tomography: 3D structures without crystals

DOE PAGES

Miao, Jianwei; Ercius, Peter; Billinge, S. J. L.

2016-09-23

Crystallography has been fundamental to the development of many fields of science over the last century. However, much of our modern science and technology relies on materials with defects and disorders, and their three-dimensional (3D) atomic structures are not accessible to crystallography. One method capable of addressing this major challenge is atomic electron tomography. By combining advanced electron microscopes and detectors with powerful data analysis and tomographic reconstruction algorithms, it is now possible to determine the 3D atomic structure of crystal defects such as grain boundaries, stacking faults, dislocations, and point defects, as well as to precisely localize the 3Dmore » coordinates of individual atoms in materials without assuming crystallinity. In this work, we review the recent advances and the interdisciplinary science enabled by this methodology. We also outline further research needed for atomic electron tomography to address long-standing unresolved problems in the physical sciences.« less

Effect of dynamic disorder on charge transport along a pentacene chain

NASA Astrophysics Data System (ADS)

Böhlin, J.; Linares, M.; Stafström, S.

2011-02-01

The lattice equation of motion and a numerical solution of the time-dependent Schrödinger equation provide us with a microscopic picture of charge transport in highly ordered molecular crystals. We have chosen the pentacene single crystal as a model system, and we study charge transport as a function of phonon-mode time-dependent fluctuations in the intermolecular electron transfer integral. For comparison, we include similar fluctuations also in the intramolecular potentials. The variance in these energy quantities is closely related to the temperature of the system. The pentacene system is shown to be very sensitive to fluctuation in the intermolecular transfer integral, revealing a transition from adiabatic to nonadiabatic polaron transport for increasing temperatures. The extension of the polaron at temperatures above 200 K is limited by the electron localization length rather than the interplay between the electron transfer integral and the electron-phonon coupling strength.

Quantitative analysis of magnetic spin and orbital moments from an oxidized iron (1 1 0) surface using electron magnetic circular dichroism.

PubMed

Thersleff, Thomas; Rusz, Jan; Rubino, Stefano; Hjörvarsson, Björgvin; Ito, Yasuo; J Zaluzec, Nestor; Leifer, Klaus

2015-08-17

Understanding the ramifications of reduced crystalline symmetry on magnetic behavior is a critical step in improving our understanding of nanoscale and interfacial magnetism. However, investigations of such effects are often controversial largely due to the challenges inherent in directly correlating nanoscale stoichiometry and structure to magnetic behavior. Here, we describe how to use Transmission Electron Microscope (TEM) to obtain Electron Magnetic Circular Dichroism (EMCD) signals as a function of scattering angle to locally probe the magnetic behavior of thin oxide layers grown on an Fe (1 1 0) surface. Experiments and simulations both reveal a strong dependence of the magnetic orbital to spin ratio on its scattering vector in reciprocal space. We exploit this variation to extract the magnetic properties of the oxide cladding layer, showing that it locally may exhibit an enhanced orbital to spin moment ratio. This finding is supported here by both spatially and angularly resolved EMCD measurements, opening up the way for compelling investigations into how magnetic properties are affected by nanoscale features.

Quantitative analysis of magnetic spin and orbital moments from an oxidized iron (1 1 0) surface using electron magnetic circular dichroism

DOE PAGES

Thersleff, Thomas; Rusz, Jan; Rubino, Stefano; ...

2015-08-17

Understanding the ramifications of reduced crystalline symmetry on magnetic behavior is a critical step in improving our understanding of nanoscale and interfacial magnetism. However, investigations of such effects are often controversial largely due to the challenges inherent in directly correlating nanoscale stoichiometry and structure to magnetic behavior. Here, we describe how to use Transmission Electron Microscope (TEM) to obtain Electron Magnetic Circular Dichroism (EMCD) signals as a function of scattering angle to locally probe the magnetic behavior of thin oxide layers grown on an Fe (1 1 0) surface. Experiments and simulations both reveal a strong dependence of the magneticmore » orbital to spin ratio on its scattering vector in reciprocal space. We exploit this variation to extract the magnetic properties of the oxide cladding layer, showing that it locally may exhibit an enhanced orbital to spin moment ratio. This finding is supported here by both spatially and angularly resolved EMCD measurements, opening up the way for compelling investigations into how magnetic properties are affected by nanoscale features.« less

Synthesis and characterization of Her2-NLP peptide conjugates targeting circulating breast cancer cells: cellular uptake and localization by fluorescent microscopic imaging.

PubMed

Cai, Huawei; Singh, Ajay N; Sun, Xiankai; Peng, Fangyu

2015-01-01

To synthesize a fluorescent Her2-NLP peptide conjugate consisting of Her2/neu targeting peptide and nuclear localization sequence peptide (NLP) and assess its cellular uptake and intracellular localization for radionuclide cancer therapy targeting Her2/neu-positive circulating breast cancer cells (CBCC). Fluorescent Cy5.5 Her2-NLP peptide conjugate was synthesized by coupling a bivalent peptide sequence, which consisted of a Her2-binding peptide (NH2-GSGKCCYSL) and an NLP peptide (CGYGPKKKRKVGG) linked by a polyethylene glycol (PEG) chain with 6 repeating units, with an activated Cy5.5 ester. The conjugate was separated and purified by HPLC and then characterized by Maldi-MS. The intracellular localization of fluorescent Cy5.5 Her2-NLP peptide conjugate was assessed by fluorescent microscopic imaging using a confocal microscope after incubation of Cy5.5-Her2-NLP with Her2/neu positive breast cancer cells and Her2/neu negative control breast cancer cells, respectively. Fluorescent signals were detected in cytoplasm of Her2/neu positive breast cancer cells (SKBR-3 and BT474 cell lines), but not or little in cytoplasm of Her2/neu negative breast cancer cells (MDA-MB-231), after incubation of the breast cancer cells with Cy5.5-Her2-NLP conjugates in vitro. No fluorescent signals were detected within the nuclei of Her2/neu positive SKBR-3 and BT474 breast cancer cells, neither Her2/neu negative MDA-MB-231 cells, incubated with the Cy5.5-Her2-NLP peptide conjugates, suggesting poor nuclear localization of the Cy5.5-Her2-NLP conjugates localized within the cytoplasm after their cellular uptake and internalization by the Her2/neu positive breast cancer cells. Her2-binding peptide (KCCYSL) is a promising agent for radionuclide therapy of Her2/neu positive breast cancer using a β(-) or α emitting radionuclide, but poor nuclear localization of the Her2-NLP peptide conjugates may limit its use for eradication of Her2/neu-positive CBCC using I-125 or other Auger electron emitting radionuclide.

Dynamical control of electron-phonon interactions with high-frequency light

NASA Astrophysics Data System (ADS)

Dutreix, C.; Katsnelson, M. I.

2017-01-01

This work addresses the one-dimensional problem of Bloch electrons when they are rapidly driven by a homogeneous time-periodic light and linearly coupled to vibrational modes. Starting from a generic time-periodic electron-phonon Hamiltonian, we derive a time-independent effective Hamiltonian that describes the stroboscopic dynamics up to the third order in the high-frequency limit. This yields nonequilibrium corrections to the electron-phonon coupling that are controllable dynamically via the driving strength. This shows in particular that local Holstein interactions in equilibrium are corrected by antisymmetric Peierls interactions out of equilibrium, as well as by phonon-assisted hopping processes that make the dynamical Wannier-Stark localization of Bloch electrons impossible. Subsequently, we revisit the Holstein polaron problem out of equilibrium in terms of effective Green's functions, and specify explicitly how the binding energy and effective mass of the polaron can be controlled dynamically. These tunable properties are reported within the weak- and strong-coupling regimes since both can be visited within the same material when varying the driving strength. This work provides some insight into controllable microscopic mechanisms that may be involved during the multicycle laser irradiations of organic molecular crystals in ultrafast pump-probe experiments, although it should also be suitable for realizations in shaken optical lattices of ultracold atoms.

Compartmentalization of membrane trafficking, glucose transport, glycolysis, actin, tubulin and the proteasome in the cytoplasmic droplet/Hermes body of epididymal sperm.

PubMed

Au, Catherine E; Hermo, Louis; Byrne, Elliot; Smirle, Jeffrey; Fazel, Ali; Kearney, Robert E; Smith, Charles E; Vali, Hojatollah; Fernandez-Rodriguez, Julia; Simon, Paul H G; Mandato, Craig; Nilsson, Tommy; Bergeron, John J M

2015-08-01

Discovered in 1909 by Retzius and described mainly by morphology, the cytoplasmic droplet of sperm (renamed here the Hermes body) is conserved among all mammalian species but largely undefined at the molecular level. Tandem mass spectrometry of the isolated Hermes body from rat epididymal sperm characterized 1511 proteins, 43 of which were localized to the structure in situ by light microscopy and two by quantitative electron microscopy localization. Glucose transporter 3 (GLUT-3) glycolytic enzymes, selected membrane traffic and cytoskeletal proteins were highly abundant and concentrated in the Hermes body. By electron microscope gold antibody labelling, the Golgi trafficking protein TMED7/p27 localized to unstacked flattened cisternae of the Hermes body, as did GLUT-3, the most abundant protein. Its biogenesis was deduced through the mapping of protein expression for all 43 proteins during male germ cell differentiation in the testis. It is at the terminal step 19 of spermiogenesis that the 43 characteristic proteins accumulated in the nascent Hermes body. © 2015 The Authors.

Visualizing Morphological Changes of Abscission Zone Cells in Arabidopsis by Scanning Electron Microscope.

PubMed

Shi, Chun-Lin; Butenko, Melinka A

2018-01-01

Scanning electron microscope (SEM) is a type of electron microscope which produces detailed images of surface structures. It has been widely used in plants and animals to study cellular structures. Here, we describe a detailed protocol to prepare samples of floral abscission zones (AZs) for SEM, as well as further image analysis. We show that it is a powerful tool to detect morphologic changes at the cellular level during the course of abscission in wild-type plants and to establish the details of phenotypic alteration in abscission mutants.

Scanning electron microscopic appearance of rat otocyst of the twelfth postcoital day: elaboration of a method.

PubMed

Marovitz, W F; Khan, K M

1977-01-01

A method for removal, fixation, microdissection, and drying of early rat otocyst for examination by the scanning electron microscope is elaborated. Tissues were dissected, fixed as for conventional transmission electron microscopy and dried by critical point evaporation using amylacetate as the transitional fluid and carbon dioxide as the pressure head. Otocysts were either dissected at the time of initial fixation, or subsequent to drying. The otocyst of the 12th postcoital day was used as a model system in this preliminary report. Critical point drying retained the overall configuration and the fine ultrastructural detail of the otocyst. The interior otocystic surface was visualized and cilia bearing cells of the luminal surface were identified. Most if not all of these cells had a comspicuous, but short kinocillum which terminated in an ovoid bulb. The scanning electron microscopic appearance was correlated to the transmission electron microscopic image seen in the second paper in this Supplement.

Atmospheric scanning electron microscope for correlative microscopy.

PubMed

Morrison, Ian E G; Dennison, Clare L; Nishiyama, Hidetoshi; Suga, Mitsuo; Sato, Chikara; Yarwood, Andrew; O'Toole, Peter J

2012-01-01

The JEOL ClairScope is the first truly correlative scanning electron and optical microscope. An inverted scanning electron microscope (SEM) column allows electron images of wet samples to be obtained in ambient conditions in a biological culture dish, via a silicon nitride film window in the base. A standard inverted optical microscope positioned above the dish holder can be used to take reflected light and epifluorescence images of the same sample, under atmospheric conditions that permit biochemical modifications. For SEM, the open dish allows successive staining operations to be performed without moving the holder. The standard optical color camera used for fluorescence imaging can be exchanged for a high-sensitivity monochrome camera to detect low-intensity fluorescence signals, and also cathodoluminescence emission from nanophosphor particles. If these particles are applied to the sample at a suitable density, they can greatly assist the task of perfecting the correlation between the optical and electron images. Copyright © 2012 Elsevier Inc. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Juffmann, Thomas; Koppell, Stewart A.; Klopfer, Brannon B.

Feynman once asked physicists to build better electron microscopes to be able to watch biology at work. While electron microscopes can now provide atomic resolution, electron beam induced specimen damage precludes high resolution imaging of sensitive materials, such as single proteins or polymers. Here, we use simulations to show that an electron microscope based on a multi-pass measurement protocol enables imaging of single proteins, without averaging structures over multiple images. While we demonstrate the method for particular imaging targets, the approach is broadly applicable and is expected to improve resolution and sensitivity for a range of electron microscopy imaging modalities,more » including, for example, scanning and spectroscopic techniques. The approach implements a quantum mechanically optimal strategy which under idealized conditions can be considered interaction-free.« less

Electron holography study of magnetization behavior in the writer pole of a perpendicular magnetic recording head by a 1 MV transmission electron microscope.

PubMed

Hirata, Kei; Ishida, Yoichi; Akashi, Tetsuya; Shindo, Daisuke; Tonomura, Akira

2012-01-01

The magnetic domain structure of the writer poles of perpendicular magnetic recording heads was studied using electron holography. Although the domain structure of a 100-nm-thick writer pole could be observed with a 300 kV transmission electron microscope, that of the 250-nm-thick writer pole could not be analyzed due to the limited transmission capability of the instrument. On the other hand, the detailed domain structure of the 250-nm-thick writer pole was successfully analyzed by a 1 MV electron microscope using its high transmission capability. The thickness and material dependency of the domain structure of a writer pole were discussed.

Attainment of 40.5 pm spatial resolution using 300 kV scanning transmission electron microscope equipped with fifth-order aberration corrector.

PubMed

Morishita, Shigeyuki; Ishikawa, Ryo; Kohno, Yuji; Sawada, Hidetaka; Shibata, Naoya; Ikuhara, Yuichi

2018-02-01

The achievement of a fine electron probe for high-resolution imaging in scanning transmission electron microscopy requires technological developments, especially in electron optics. For this purpose, we developed a microscope with a fifth-order aberration corrector that operates at 300 kV. The contrast flat region in an experimental Ronchigram, which indicates the aberration-free angle, was expanded to 70 mrad. By using a probe with convergence angle of 40 mrad in the scanning transmission electron microscope at 300 kV, we attained the spatial resolution of 40.5 pm, which is the projected interatomic distance between Ga-Ga atomic columns of GaN observed along [212] direction.

Optics of high-performance electron microscopes*

PubMed Central

Rose, H H

2008-01-01

During recent years, the theory of charged particle optics together with advances in fabrication tolerances and experimental techniques has lead to very significant advances in high-performance electron microscopes. Here, we will describe which theoretical tools, inventions and designs have driven this development. We cover the basic theory of higher-order electron optics and of image formation in electron microscopes. This leads to a description of different methods to correct aberrations by multipole fields and to a discussion of the most advanced design that take advantage of these techniques. The theory of electron mirrors is developed and it is shown how this can be used to correct aberrations and to design energy filters. Finally, different types of energy filters are described. PMID:27877933

Anomaly Detection in Nanofibrous Materials by CNN-Based Self-Similarity.

PubMed

Napoletano, Paolo; Piccoli, Flavio; Schettini, Raimondo

2018-01-12

Automatic detection and localization of anomalies in nanofibrous materials help to reduce the cost of the production process and the time of the post-production visual inspection process. Amongst all the monitoring methods, those exploiting Scanning Electron Microscope (SEM) imaging are the most effective. In this paper, we propose a region-based method for the detection and localization of anomalies in SEM images, based on Convolutional Neural Networks (CNNs) and self-similarity. The method evaluates the degree of abnormality of each subregion of an image under consideration by computing a CNN-based visual similarity with respect to a dictionary of anomaly-free subregions belonging to a training set. The proposed method outperforms the state of the art.

Co-localization of endogenous Arf6 and its activator EFA6D in the granular convoluted tubule cells of mouse submandibular glands under normal conditions and when stimulated by isoproterenol, noradrenaline and carbachol.

PubMed

Tachow, Apussara; Thoungseabyoun, Wipawee; Phuapittayalert, Laorrat; Petcharat, Kanoktip; Sakagami, Hiroyuki; Kondo, Hisatake; Hipkaeo, Wiphawi

2017-10-01

This study proposed to investigate the localization at light and electron microscopic levels of Arf6 and its activator EFA6D in the mouse submandibular gland (SMG) under normal conditions and when stimulated by adrenergic or cholinergic agonists. SMGs of male adult mice were utilized for immunoblotting and immuno-light and -electron microscopic analyses. Isoproterenol and noradrenalin were used as adrenergics, while carbachol was used for the cholinergic stimulant. SMGs were examined at 15, 30, 60 and 120min after intraperitoneal injection of these agents. Immunoreactivities for both Arf6 and its activator EFA6D were similarly intense in the basolateral domain of GCTs, but no significant immunoreactivities were seen in the apical domain of GCT cells or any domain of acinar cells under normal conditions. In immuno-electron microscopy, the immunoreactive materials were mainly deposited on the basolateral plasma membranes and subjacent cytoplasm. Shortly after injection of isoproterenol and noradrenaline, but not carbachol, the immunoreactivities for both molecules were additionally seen on the apical plasmalemma of most, if not all, GCT cells, but not acinar cells. The present findings suggest that the direct involvement of Arf6/EFA6D in regulatory exocytosis at the apical plasma membrane of acinar and GCT cells is apparently to be smaller, if present, than that of endocytosis at the basolateral membranes of GCT cells under normal conditions. This also suggests that the two molecules function additionally at the apical membrane of GCT cells for modulation of saliva secretion under β-adrenoceptor stimulation. Copyright © 2017 Elsevier Ltd. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rau, E. I.; Orlikovskiy, N. A.; Ivanova, E. S.

A new highly efficient design for semiconductor detectors of intermediate-energy electrons (1-50 keV) for application in scanning electron microscopes is proposed. Calculations of the response function of advanced detectors and control experiments show that the efficiency of the developed devices increases on average twofold, which is a significant positive factor in the operation of modern electron microscopes in the mode of low currents and at low primary electron energies.

Using the scanning electron microscope on the production line to assure quality semiconductors

NASA Technical Reports Server (NTRS)

Adolphsen, J. W.; Anstead, R. J.

1972-01-01

The use of the scanning electron microscope to detect metallization defects introduced during batch processing of semiconductor devices is discussed. A method of determining metallization integrity was developed which culminates in a procurement specification using the scanning microscope on the production line as a quality control tool. Batch process control of the metallization operation is monitored early in the manufacturing cycle.

Influence of mechanical noise inside a scanning electron microscope

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gaudenzi de Faria, Marcelo; Haddab, Yassine, E-mail: yassine.haddab@femto-st.fr; Le Gorrec, Yann

The scanning electron microscope is becoming a popular tool to perform tasks that require positioning, manipulation, characterization, and assembly of micro-components. However, some of these applications require a higher level of performance with respect to dynamics and precision of positioning. One limiting factor is the presence of unidentified noises and disturbances. This work aims to study the influence of mechanical disturbances generated by the environment and by the microscope, identifying how these can affect elements in the vacuum chamber. To achieve this objective, a dedicated setup, including a high-resolution vibrometer, was built inside the microscope. This work led to themore » identification and quantification of main disturbances and noise sources acting on a scanning electron microscope. Furthermore, the effects of external acoustic excitations were analysed. Potential applications of these results include noise compensation and real-time control for high accuracy tasks.« less

Ultrastructural localization of hair keratins, high sulfur keratin-associated proteins and sulfhydryl oxidase in the human hair.

PubMed

Alibardi, Lorenzo

2017-03-01

Hardening of the human hair shaft during cornification results from the bonding of keratins and keratin-associated proteins. In situ hybridization and light immunocytochemical studies have shown the general distribution of different keratins and some associated proteins but not determined their ultrastructural localization. I report here the localization of hair keratins, two high-sulfur keratin-associated proteins and sulfhydryl oxidase has been studied under the transmission electron microscope in the cornification zone of the human hair. The ultrastructural study on keratin distribution in general confirms previous light microscopic studies. Sulfur-rich KAP1 is mainly cortical but the labeling disappears in fully cornified cortical cells while a diffuse labeling is also present in differentiating cuticle cells. Sulfur-rich K26 immunolocalization is only detected in the exocuticle and endocuticle. Sparse labeling for sulfhydryl oxidase occurs in differentiating cortical cells but is weak and uneven in cuticle cells and absent in medulla and inner root sheath. Labeling disappears in the upper fully cornified cortex and cuticle. The observations indicate that sulfhydryl oxidase and keratin associated proteins are initially produced in the cytoplasm among keratin bundles accumulating in cortical and cuticle cells but these proteins undergo changes during the following cornification that alter the epitopes tagged by the antibodies.

78 FR 5776 - Columbia University, et al.; Notice of Consolidated Decision on Applications for Duty-Free Entry...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-01-28

... 94305. Instrument: Titan 80-300 Environmental Transmission Electron Microscope. Manufacturer: FEI Co.../Scanning Electron Microscope. Manufacturer: FEI Co., the Netherlands. Intended Use: See notice at 77 FR...

Fine needle aspiration (FNA) of synovial sarcoma--a comparative histological-cytological study of 15 cases, including immunohistochemical, electron microscopic and cytogenetic examination and DNA-ploidy analysis.

PubMed

Akerman, M; Willén, H; Carlén, B; Mandahl, N; Mertens, F

1996-06-01

A retrospective study of 25 FNAs (11 aspirates from primary tumours and 14 from recurrencies and metastases) from 15 synovial sarcomas was performed. The cytological findings were correlated with the histopathology and the value of immunohistochemical and electron microscopic examination as well as DNA-ploidy and cytogenetic analysis for diagnosis were assessed. A reproducible cellular pattern with a reliable diagnosis of spindle cell sarcoma was possible provided that the aspirates were cell rich. However, a true biphasic pattern indicative of synovial sarcoma was only seen in one of the 25 specimens. Electron microscopic examination of the aspirates was a valuable adjunctive diagnostic method, whereas immunocytochemistry and DNA-ploidy analysis were not. Immunohistochemical, electron microscopic and cytogenetic analysis were all valuable ancillary methods when performed on surgical specimens. Malignant haemangiopericytoma and fibrosarcoma were the most important differential diagnoses in the FNA specimens.

A two-dimensional Dirac fermion microscope

NASA Astrophysics Data System (ADS)

Bøggild, Peter; Caridad, José M.; Stampfer, Christoph; Calogero, Gaetano; Papior, Nick Rübner; Brandbyge, Mads

2017-06-01

The electron microscope has been a powerful, highly versatile workhorse in the fields of material and surface science, micro and nanotechnology, biology and geology, for nearly 80 years. The advent of two-dimensional materials opens new possibilities for realizing an analogy to electron microscopy in the solid state. Here we provide a perspective view on how a two-dimensional (2D) Dirac fermion-based microscope can be realistically implemented and operated, using graphene as a vacuum chamber for ballistic electrons. We use semiclassical simulations to propose concrete architectures and design rules of 2D electron guns, deflectors, tunable lenses and various detectors. The simulations show how simple objects can be imaged with well-controlled and collimated in-plane beams consisting of relativistic charge carriers. Finally, we discuss the potential of such microscopes for investigating edges, terminations and defects, as well as interfaces, including external nanoscale structures such as adsorbed molecules, nanoparticles or quantum dots.

A two-dimensional Dirac fermion microscope

PubMed Central

Bøggild, Peter; Caridad, José M.; Stampfer, Christoph; Calogero, Gaetano; Papior, Nick Rübner; Brandbyge, Mads

2017-01-01

The electron microscope has been a powerful, highly versatile workhorse in the fields of material and surface science, micro and nanotechnology, biology and geology, for nearly 80 years. The advent of two-dimensional materials opens new possibilities for realizing an analogy to electron microscopy in the solid state. Here we provide a perspective view on how a two-dimensional (2D) Dirac fermion-based microscope can be realistically implemented and operated, using graphene as a vacuum chamber for ballistic electrons. We use semiclassical simulations to propose concrete architectures and design rules of 2D electron guns, deflectors, tunable lenses and various detectors. The simulations show how simple objects can be imaged with well-controlled and collimated in-plane beams consisting of relativistic charge carriers. Finally, we discuss the potential of such microscopes for investigating edges, terminations and defects, as well as interfaces, including external nanoscale structures such as adsorbed molecules, nanoparticles or quantum dots. PMID:28598421

Scanning Microscopes Using X Rays and Microchannels

NASA Technical Reports Server (NTRS)

Wang, Yu

2003-01-01

Scanning microscopes that would be based on microchannel filters and advanced electronic image sensors and that utilize x-ray illumination have been proposed. Because the finest resolution attainable in a microscope is determined by the wavelength of the illumination, the xray illumination in the proposed microscopes would make it possible, in principle, to achieve resolutions of the order of nanometers about a thousand times as fine as the resolution of a visible-light microscope. Heretofore, it has been necessary to use scanning electron microscopes to obtain such fine resolution. In comparison with scanning electron microscopes, the proposed microscopes would likely be smaller, less massive, and less expensive. Moreover, unlike in scanning electron microscopes, it would not be necessary to place specimens under vacuum. The proposed microscopes are closely related to the ones described in several prior NASA Tech Briefs articles; namely, Miniature Microscope Without Lenses (NPO-20218), NASA Tech Briefs, Vol. 22, No. 8 (August 1998), page 43; and Reflective Variants of Miniature Microscope Without Lenses (NPO-20610), NASA Tech Briefs, Vol. 26, No. 9 (September 2002) page 6a. In all of these microscopes, the basic principle of design and operation is the same: The focusing optics of a conventional visible-light microscope are replaced by a combination of a microchannel filter and a charge-coupled-device (CCD) image detector. A microchannel plate containing parallel, microscopic-cross-section holes much longer than they are wide is placed between a specimen and an image sensor, which is typically the CCD. The microchannel plate must be made of a material that absorbs the illuminating radiation reflected or scattered from the specimen. The microchannels must be positioned and dimensioned so that each one is registered with a pixel on the image sensor. Because most of the radiation incident on the microchannel walls becomes absorbed, the radiation that reaches the image sensor consists predominantly of radiation that was launched along the longitudinal direction of the microchannels. Therefore, most of the radiation arriving at each pixel on the sensor must have traveled along a straight line from a corresponding location on the specimen. Thus, there is a one-to-one mapping from a point on a specimen to a pixel in the image sensor, so that the output of the image sensor contains image information equivalent to that from a microscope.

Localizing high-lying Rydberg wave packets with two-color laser fields

NASA Astrophysics Data System (ADS)

Larimian, Seyedreza; Lemell, Christoph; Stummer, Vinzenz; Geng, Ji-Wei; Roither, Stefan; Kartashov, Daniil; Zhang, Li; Wang, Mu-Xue; Gong, Qihuang; Peng, Liang-You; Yoshida, Shuhei; Burgdörfer, Joachim; Baltuška, Andrius; Kitzler, Markus; Xie, Xinhua

2017-08-01

We demonstrate control over the localization of high-lying Rydberg wave packets in argon atoms with phase-locked orthogonally polarized two-color laser fields. With a reaction microscope, we measure ionization signals of high-lying Rydberg states induced by a weak dc field and blackbody radiation as a function of the relative phase between the two-color fields. We find that the dc-field-ionization yield of high-lying Rydberg argon atoms oscillates with the relative two-color phase with a period of 2 π while the photoionization signal by blackbody radiation shows a period of π . Accompanying simulations show that these observations are a clear signature of the asymmetric localization of electrons recaptured into very elongated (low angular momentum) high-lying Rydberg states after conclusion of the laser pulse. Our findings thus open an effective pathway to control the localization of high-lying Rydberg wave packets.

The hybrid lattice of K(x)Fe(2-y)Se2: where superconductivity and magnetism coexist.

PubMed

Louca, Despina; Park, Keeseong; Li, Bing; Neuefeind, Joerg; Yan, Jiaqiang

2013-01-01

Much remains unknown of the microscopic origin of superconductivity in atomically disordered systems of amorphous alloys or in crystals riddled with defects. A manifestation of this conundrum is envisaged in the highly defective superconductor of K(x)Fe(2-y)Se2. How can superconductivity survive under such crude conditions that call for strong electron localization? Here, we show that the Fe sublattice is locally distorted and accommodates two kinds of Fe valence environments giving rise to a bimodal bond-distribution, with short and long Fe bonds. The bimodal bonds are present even as the system becomes superconducting in the presence of antiferromagnetism, with the weight continuously shifting from the short to the long with increasing K content. Such a hybrid state is most likely found in cuprates as well while our results point to the importance of the local atomic symmetry by which exchange interactions between local moments materialize.

Development of the field of structural physiology

PubMed Central

FUJIYOSHI, Yoshinori

2015-01-01

Electron crystallography is especially useful for studying the structure and function of membrane proteins — key molecules with important functions in neural and other cells. Electron crystallography is now an established technique for analyzing the structures of membrane proteins in lipid bilayers that closely simulate their natural biological environment. Utilizing cryo-electron microscopes with helium-cooled specimen stages that were developed through a personal motivation to understand the functions of neural systems from a structural point of view, the structures of membrane proteins can be analyzed at a higher than 3 Å resolution. This review covers four objectives. First, I introduce the new research field of structural physiology. Second, I recount some of the struggles involved in developing cryo-electron microscopes. Third, I review the structural and functional analyses of membrane proteins mainly by electron crystallography using cryo-electron microscopes. Finally, I discuss multifunctional channels named “adhennels” based on structures analyzed using electron and X-ray crystallography. PMID:26560835

Development of an environmental high-voltage electron microscope for reaction science.

PubMed

Tanaka, Nobuo; Usukura, Jiro; Kusunoki, Michiko; Saito, Yahachi; Sasaki, Katuhiro; Tanji, Takayoshi; Muto, Shunsuke; Arai, Shigeo

2013-02-01

Environmental transmission electron microscopy and ultra-high resolution electron microscopic observation using aberration correctors have recently emerged as topics of great interest. The former method is an extension of the so-called in situ electron microscopy that has been performed since the 1970s. Current research in this area has been focusing on dynamic observation with atomic resolution under gaseous atmospheres and in liquids. Since 2007, Nagoya University has been developing a new 1-MV high voltage (scanning) transmission electron microscope that can be used to observe nanomaterials under conditions that include the presence of gases, liquids and illuminating lights, and it can be also used to perform mechanical operations to nanometre-sized areas as well as electron tomography and elemental analysis by electron energy loss spectroscopy. The new instrument has been used to image and analyse various types of samples including biological ones.

Nucleotide-Specific Contrast for DNA Sequencing by Electron Spectroscopy.

PubMed

Mankos, Marian; Persson, Henrik H J; N'Diaye, Alpha T; Shadman, Khashayar; Schmid, Andreas K; Davis, Ronald W

2016-01-01

DNA sequencing by imaging in an electron microscope is an approach that holds promise to deliver long reads with low error rates and without the need for amplification. Earlier work using transmission electron microscopes, which use high electron energies on the order of 100 keV, has shown that low contrast and radiation damage necessitates the use of heavy atom labeling of individual nucleotides, which increases the read error rates. Other prior work using scattering electrons with much lower energy has shown to suppress beam damage on DNA. Here we explore possibilities to increase contrast by employing two methods, X-ray photoelectron and Auger electron spectroscopy. Using bulk DNA samples with monomers of each base, both methods are shown to provide contrast mechanisms that can distinguish individual nucleotides without labels. Both spectroscopic techniques can be readily implemented in a low energy electron microscope, which may enable label-free DNA sequencing by direct imaging.

High-resolution electron microscope

NASA Technical Reports Server (NTRS)

Nathan, R.

1977-01-01

Employing scanning transmission electron microscope as interferometer, relative phases of diffraction maximums can be determined by analysis of dark field images. Synthetic aperture technique and Fourier-transform computer processing of amplitude and phase information provide high resolution images at approximately one angstrom.

75 FR 9867 - University of Pittsburgh, et al

Federal Register 2010, 2011, 2012, 2013, 2014

2010-03-04

... DEPARTMENT OF COMMERCE International Trade Administration University of Pittsburgh, et al.; Notice of Consolidated Decision on Applications for Duty-Free Entry of Electron Microscopes This is a...: University of Pittsburgh, Pittsburgh, PA 15260. Instrument: Electron Microscope. Manufacturer: JEOL, Ltd...

Infrared nanoscopy down to liquid helium temperatures

NASA Astrophysics Data System (ADS)

Lang, Denny; Döring, Jonathan; Nörenberg, Tobias; Butykai, Ádám; Kézsmárki, István; Schneider, Harald; Winnerl, Stephan; Helm, Manfred; Kehr, Susanne C.; Eng, Lukas M.

2018-03-01

We introduce a scattering-type scanning near-field infrared microscope (s-SNIM) for the local scale near-field sample analysis and spectroscopy from room temperature down to liquid helium (LHe) temperature. The extension of s-SNIM down to T = 5 K is in particular crucial for low-temperature phase transitions, e.g., for the examination of superconductors, as well as low energy excitations. The low temperature (LT) s-SNIM performance is tested with CO2-IR excitation at T = 7 K using a bare Au reference and a structured Si/SiO2-sample. Furthermore, we quantify the impact of local laser heating under the s-SNIM tip apex by monitoring the light-induced ferroelectric-to-paraelectric phase transition of the skyrmion-hosting multiferroic material GaV4S8 at Tc = 42 K. We apply LT s-SNIM to study the spectral response of GaV4S8 and its lateral domain structure in the ferroelectric phase by the mid-IR to THz free-electron laser-light source FELBE at the Helmholtz-Zentrum Dresden-Rossendorf, Germany. Notably, our s-SNIM is based on a non-contact atomic force microscope (AFM) and thus can be complemented in situ by various other AFM techniques, such as topography profiling, piezo-response force microscopy (PFM), and/or Kelvin-probe force microscopy (KPFM). The combination of these methods supports the comprehensive study of the mutual interplay in the topographic, electronic, and optical properties of surfaces from room temperature down to 5 K.

The distribution of serum albumin in the rat testis, studied by electron microscope immunocytochemistry on ultrathin frozen sections.

PubMed

Christensen, A K; Komorowski, T E; Wilson, B; Ma, S F; Stevens, R W

1985-05-01

The distribution of serum albumin is of interest in the rat testis because this protein is the principal carrier for testosterone in the plasma and interstitial fluid of this species. We have localized extravascular serum albumin in the rat testis at the electron microscope level, using gold particle immunocytochemistry on ultrathin frozen sections of tissue fixed lightly by perfusion. The same localization was obtained with three different antisera. Preabsorption and normal rabbit serum controls were negative, and Western blots of testis extracts showed major activity only at the molecular weight of albumin. Serum albumin occurred in substantial concentration throughout extracellular space in the interstitial tissue, as well as in the space between the boundary layer and the base of the seminiferous epithelium. Immunoreactivity extended between Sertoli cells, as well as around spermatogonia and early primary spermatocytes (to stage 11), but did not traverse the Sertoli-Sertoli junctions that comprise the blood-testis barrier. Macrophages in the interstitial tissue showed some endocytic activity. If perfusion fixation was carried out in a manner that flushed most of the albumin from the interstitial space, then a layer of albumin remained on the surface of Leydig cells and many macrophages but was minimal or absent on the surface of other cell types that are normally in contact with albumin, such as Sertoli cells, spermatogonia, myoid cells, lymphatic endothelium, fibroblasts, or cells of blood vessels.

Development of a miniature scanning electron microscope for in-flight analysis of comet dust

NASA Technical Reports Server (NTRS)

Conley, J. M.; Bradley, J. G.; Giffin, C. E.; Albee, A. L.; Tomassian, A. D.

1983-01-01

A description is presented of an instrument which was developed with the original goal of being flown on the International Comet Mission, scheduled for a 1985 launch. The Scanning Electron Microscope and Particle Analyzer (SEMPA) electron miniprobe is a miniaturized electrostatically focused electron microscope and energy dispersive X-ray analyzer for in-flight analysis of comet dust particles. It was designed to be flown on board a comet rendezvous spacecraft. Other potential applications are related to asteroid rendezvous and planetary lander missions. According to the development objectives, SEMPA miniprobe is to have the capability for imaging and elemental analysis of particles in the size range of 0.25 microns and larger.

Profiling with the electron microscope.

NASA Technical Reports Server (NTRS)

Vedder, J. F.; Lem, H. Y.

1972-01-01

Discussion of a profiling technique using a scanning electron microscope for obtaining depth information on a single micrograph of a small specimen. A stationary electron beam is used to form a series of contamination spots in a line across the specimen. Micrographs obtained by this technique are useful as a means of projection and display where stereo viewers are not practical.

Electron density distribution in BaPb{sub 1-x}Sb{sub x}O{sub 3} superconducting oxides studied by double nuclear magnetic resonance methods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Piskunov, Yu. V., E-mail: piskunov@imp.uran.ru; Ogloblichev, V. V.; Arapova, I. Yu.

2011-11-15

The effect of charge disorder on the formation of an inhomogeneous state of the electron system in the conduction band in BaPb{sub 1-x}Sb{sub x}O{sub 3} superconducting oxides is investigated experimentally by NMR methods. The NMR spectra of {sup 17}O are measured systematically, and the contributions from {sup 17}O atoms with different cation nearest surroundings are identified. It is found that microscopic regions with an elevated spin density of charge carriers are formed within two coordination spheres near antimony ions. Nuclei of the superconducting phase of the oxide (regions with an elevated antimony concentration) microscopically distributed over the sample are detectedmore » in compounds with x = 0.25 and 0.33. Experiments in which a double resonance signal of the spin echo of {sup 17}O-{sup 207}Pb and {sup 17}O-{sup 121}Sb are measured in the metal phase of BaPb{sub 1-x}Sb{sub x}O{sub 3} oxides are carried out for the first time. The constants of indirect heteronuclear spin-spin {sup 17}O-{sup 207}Pb interaction are determined as functions of the local Knight shift {sub 207}Ks. The estimates of the constants of the indirect interaction between the nuclei of the nearest neighbors (O-Pb and Pb-Pb atoms) and analysis of evolution of the NMR spectra of {sup 17}O upon a change in the antimony concentration are convincing evidence in favor of the development of a microscopically inhomogeneous state of the electron system in the metal phase of BaPb{sub 1-x}Sb{sub x}O{sub 3} oxides.« less

Multiorbital kinetic effects on charge ordering of frustrated electrons on the triangular lattice

NASA Astrophysics Data System (ADS)

Février, C.; Fratini, S.; Ralko, A.

2015-06-01

The role of the multiorbital effects on the emergence of frustrated electronic orders on the triangular lattice at half filling is investigated through an extended spinless fermion Hubbard model. By using two complementary approaches, unrestricted Hartree-Fock and exact diagonalizations, we unravel a very rich phase diagram controlled by the strength of both local and off-site Coulomb interactions and by the interorbital hopping anisotropy ratio t'/t . Three robust unconventional electronic phases, a pinball liquid, an inverse pinball liquid, and a large-unit-cell √{12 }×√{12 } droplet phase, are found to be generic in the triangular geometry, being controlled by the band structure parameters. The latter are also stabilized in the isotropic limit of our microscopic model, which recovers the standard SU(2) spinful extended single-band Hubbard model.

Temperature Measurement by a Nanoscale Electron Probe Using Energy Gain and Loss Spectroscopy

NASA Astrophysics Data System (ADS)

Idrobo, Juan Carlos; Lupini, Andrew R.; Feng, Tianli; Unocic, Raymond R.; Walden, Franklin S.; Gardiner, Daniel S.; Lovejoy, Tracy C.; Dellby, Niklas; Pantelides, Sokrates T.; Krivanek, Ondrej L.

2018-03-01

Heat dissipation in integrated nanoscale devices is a major issue that requires the development of nanoscale temperature probes. Here, we report the implementation of a method that combines electron energy gain and loss spectroscopy to provide a direct measurement of the local temperature in the nanoenvironment. Loss and gain peaks corresponding to an optical-phonon mode in boron nitride were measured from room temperature to ˜1600 K . Both loss and gain peaks exhibit a shift towards lower energies as the sample is heated up. First-principles calculations of the temperature-induced phonon frequency shifts provide insights into the origin of this effect and confirm the experimental data. The experiments and theory presented here open the doors to the study of anharmonic effects in materials by directly probing phonons in the electron microscope.

Visualization of multipolar longitudinal and transversal surface plasmon modes in nanowire dimers.

PubMed

Alber, Ina; Sigle, Wilfried; Müller, Sven; Neumann, Reinhard; Picht, Oliver; Rauber, Markus; van Aken, Peter A; Toimil-Molares, Maria Eugenia

2011-12-27

We study the transversal and longitudinal localized surface plasmon resonances in single nanowires and nanowire dimers excited by the fast traveling electron beam in a transmission electron microscope equipped with high-resolution electron energy-loss spectroscopy. Bright and dark longitudinal modes up to the fifth order are resolved on individual metallic nanowires. On nanowire dimers, mode splitting into bonding and antibonding is measured up to the third order for several dimers with various aspect ratio and controlled gap size. We observe that the electric field maxima of the bonding modes are shifted toward the gap, while the electric field maxima of the antibonding modes are shifted toward the dimer ends. Finally, we observe that the transversal mode is not detected in the region of the dimer gap and decays away from the rod more rapidly than the longitudinal modes.

Modifying Surface Chemistry of Metal Oxides for Boosting Dissolution Kinetics in Water by Liquid Cell Electron Microscopy.

PubMed

Lu, Yue; Geng, Jiguo; Wang, Kuan; Zhang, Wei; Ding, Wenqiang; Zhang, Zhenhua; Xie, Shaohua; Dai, Hongxing; Chen, Fu-Rong; Sui, Manling

2017-08-22

Dissolution of metal oxides is fundamentally important for understanding mineral evolution and micromachining oxide functional materials. In general, dissolution of metal oxides is a slow and inefficient chemical reaction. Here, by introducing oxygen deficiencies to modify the surface chemistry of oxides, we can boost the dissolution kinetics of metal oxides in water, as in situ demonstrated in a liquid environmental transmission electron microscope (LETEM). The dissolution rate constant significantly increases by 16-19 orders of magnitude, equivalent to a reduction of 0.97-1.11 eV in activation energy, as compared with the normal dissolution in acid. It is evidenced from the high-resolution TEM imaging, electron energy loss spectra, and first-principle calculations where the dissolution route of metal oxides is dynamically changed by local interoperability between altered water chemistry and surface oxygen deficiencies via electron radiolysis. This discovery inspires the development of a highly efficient electron lithography method for metal oxide films in ecofriendly water, which offers an advanced technique for nanodevice fabrication.

Phase separation of electrons strongly coupled with phonons in cuprates and manganites

NASA Astrophysics Data System (ADS)

Alexandrov, Sasha

2009-03-01

Recent advanced Monte Carlo simulations have not found superconductivity and phase separation in the Hubbard model with on-site repulsive electron-electron correlations. I argue that microscopic phase separations in cuprate superconductors and colossal magnetoresistance (CMR) manganites originate from a strong electron-phonon interaction (EPI) combined with unavoidable disorder. Attractive electron correlations, caused by an almost unretarded EPI, are sufficient to overcome the direct inter-site Coulomb repulsion in these charge-transfer Mott-Hubbard insulators, so that low energy physics is that of small polarons and small bipolarons. They form clusters localized by disorder below the mobility edge, but propagate as the Bloch states above the mobility edge. I identify the Froehlich EPI as the most essential for pairing and phase separation in superconducting layered cuprates. The pairing of oxygen holes into heavy bipolarons in the paramagnetic phase (current-carrier density collapse (CCDC)) explains also CMR and high and low-resistance phase coexistence near the ferromagnetic transition of doped manganites.

Scanning probes for lithography: Manipulation and devices

NASA Astrophysics Data System (ADS)

Rolandi, Marco

2005-11-01

Scanning probes are relatively low cost equipment that can push the limit of lithography in the nanometer range, with the advantages of high resolution, accuracy in the positioning of the overlayers and no proximity aberrations. We have developed three novel scanning probe lithography (SPL) resists based on thin films of Titanium, Molybdenum and Tungsten and we have manipulated single walled carbon nanotubes using the sharp tip of an atomic force microscope (AFM) for the fabrication of nanostructures. A dendrimer-passivated Ti film was imaged in the positive and the negative tone using SPL. This is the first example of SPL imaging in both tones using a unique resist. Positive tone patterning was obtained by locally scribing the dendrimer molecules and subsequent acid etch of the deprotected Ti film. Local anodic oxidation transforms Ti into TiO2 and deposits a thin layer of amorphous carbon on the patterned areas. This is very resistive to base etch and affords negative tone imaging of the Ti surface. Molybdenum and Tungsten were patterned using local anodic oxidation. This scheme is particularly flexible thanks to the solubility in water of the fully oxidized states of the two metals. We will present the facile fabrication of several nanostructures such as of trenches, dots wires and nanoelectrodes and show the potential of this scheme for competing with conventional lithographic techniques based on radiation. Quasi one dimensional electrodes for molecular electronics applications were also fabricated by creating nanogaps in single walled carbon nanotubes. The tubes, connected to microscopic contacts, were controllably cut via local anodic oxidation using the tip of the AFM. This technique leads to nanoscopic carboxyl terminated wires to which organic molecules can be linked using covalent chemistry. This geometry is particularly useful for the high gate efficiency without the need of a thin gate dielectric and the stability of the junction. Room temperature and low temperature measurements were performed and show single electron transistor behavior for the molecular junction.

Classification of Streptomyces Spore Surfaces into Five Groups

PubMed Central

Dietz, Alma; Mathews, John

1971-01-01

Streptomyces spores surfaces have been classified into five groups, smooth, warty, spiny, hairy, and rugose, by examination of carbon replicas of spores with the transmission electron microscope and by direct examination of spores with the scanning electron microscope. Images PMID:4928607

COLONIAL GROWTH OF MYCOPLASMA GALLISEPTICUM OBSERVED WITH THE ELECTRON MICROSCOPE

PubMed Central

Shifrine, Moshe; Pangborn, Jack; Adler, Henry E.

1962-01-01

Shifrine, Moshe (University of California, Davis), Jack Pangborn, and Henry E. Adler. Colonial growth of Mycoplasma gallisepticum observed with the electron microscope. J. Bacteriol. 83:187–192. 1962.—Mycoplasma gallisepticum strain S6 was grown on collodion film on solid medium. Samples were removed every few hours, fixed, washed, shadowed, and observed with the electron microscope. Three distinct forms of growth were observed: elementary cells (hexagonally shaped), platycytes, and exoblasts. A tentative mode of growth was postulated. The significance of the angular morphology to the relation between mycoplasmas and L-forms of bacteria is discussed. Images PMID:13911868

Surface phenomenon in Electrochemical Systems

NASA Astrophysics Data System (ADS)

Gupta, Tanya

Interfaces play a critical role in the performance of electrochemical systems. This thesis focusses on interfaces in batteries and covers aspects of interfacial morphologies of metal anodes, including Silicon, Lithium and Zinc. Growth and cycling of electrochemically grown Lithium and Zinc metal structures is investigated. A new morphology of Zinc, called Hyper Dendritic Zinc is introduced. It is cycled against Prussian Blue Analogues and is shown to improve the performance of this couple significantly. Characterization of materials is done using various electron microscopy techniques ranging from Low Energy Electron Microscope (LEEM), to high energy Transmission Electron Microscope (TEM). LEEM is used for capturing subtle surface phenomenon occurring during epitaxial process of electrolyte on anode. The system studied is Silicon (100) during Chemical Vapor Deposition of Ethylene Carbonate. A strain driven relaxation theory is modeled to explain the unusual restructuring of Si substrate. The other extreme, TEM, is often used to study electrochemical processes, without clear understanding of how the high-energy electron beam can influence the sample under investigation. Here, we study the radiolysis in liquid cell TEM and emphasize on the enhancement of radiation dose at interfaces of the liquid due to generation of secondary and backscattered electrons from adjoining materials. It is shown that this effect is localized in a 10 nm region around the interface and can play a dominating role if there is an interface of liquid with heavy metals like Gold and Platinum which are frequently used as electrode materials. This analysis can be used to establish guidelines for experimentalists to follow, for accurate interpretation of their results.

In situ electronic probing of semiconducting nanowires in an electron microscope.

PubMed

Fauske, V T; Erlbeck, M B; Huh, J; Kim, D C; Munshi, A M; Dheeraj, D L; Weman, H; Fimland, B O; Van Helvoort, A T J

2016-05-01

For the development of electronic nanoscale structures, feedback on its electronic properties is crucial, but challenging. Here, we present a comparison of various in situ methods for electronically probing single, p-doped GaAs nanowires inside a scanning electron microscope. The methods used include (i) directly probing individual as-grown nanowires with a sharp nano-manipulator, (ii) contacting dispersed nanowires with two metal contacts and (iii) contacting dispersed nanowires with four metal contacts. For the last two cases, we compare the results obtained using conventional ex situ litho-graphy contacting techniques and by in situ, direct-write electron beam induced deposition of a metal (Pt). The comparison shows that 2-probe measurements gives consistent results also with contacts made by electron beam induced deposition, but that for 4-probe, stray deposition can be a problem for shorter nanowires. This comparative study demonstrates that the preferred in situ method depends on the required throughput and reliability. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

Electron beam patterning for writing of positively charged gold colloidal nanoparticles

NASA Astrophysics Data System (ADS)

Zafri, Hadar; Azougi, Jonathan; Girshevitz, Olga; Zalevsky, Zeev; Zitoun, David

2018-02-01

Synthesis at the nanoscale has progressed at a very fast pace during the last decades. The main challenge today lies in precise localization to achieve efficient nanofabrication of devices. In the present work, we report on a novel method for the patterning of gold metallic nanoparticles into nanostructures on a silicon-on-insulator (SOI) wafer. The fabrication makes use of relatively accessible equipment, a scanning electron microscope (SEM), and wet chemical synthesis. The electron beam implants electrons into the insulating material, which further anchors the positively charged Au nanoparticles by electrostatic attraction. The novel fabrication method was applied to several substrates useful in microelectronics to add plasmonic particles. The resolution and surface density of the deposition were tuned, respectively, by the electron energy (acceleration voltage) and the dose of electronic irradiation. We easily achieved the smallest written feature of 68 ± 18 nm on SOI, and the technique can be extended to any positively charged nanoparticles, while the resolution is in principle limited by the particle size distribution and the scattering of the electrons in the substrate. [Figure not available: see fulltext.

Use of fluorescence and scanning electron microscopy as tools in teaching biology

NASA Astrophysics Data System (ADS)

Ghosh, Nabarun; Silva, Jessica; Vazquez, Aracely; Das, A. B.; Smith, Don W.

2011-06-01

Recent nationwide surveys reveal significant decline in students' interest in Math and Sciences. The objective of this project was to inspire young minds in using various techniques involved in Sciences including Scanning Electron Microscopy. We used Scanning Electron Microscope in demonstrating various types of Biological samples. An SEM Tabletop model in the past decade has revolutionized the use of Scanning Electron Microscopes. Using SEM Tabletop model TM 1000 we studied biological specimens of fungal spores, pollen grains, diatoms, plant fibers, dust mites, insect parts and leaf surfaces. We also used fluorescence microscopy to view, to record and analyze various specimens with an Olympus BX40 microscope equipped with FITC and TRITC fluorescent filters, a mercury lamp source, DP-70 digital camera with Image Pro 6.0 software. Micrographs were captured using bright field microscopy, the fluoresceinisothiocyanate (FITC) filter, and the tetramethylrhodamine (TRITC) filter settings at 40X. A high pressure mercury lamp or UV source was used to excite the storage molecules or proteins which exhibited autofluorescence. We used fluorescent microscopy to confirm the localization of sugar beet viruses in plant organs by viewing the vascular bundles in the thin sections of the leaves and other tissues. We worked with the REU summer students on sample preparation and observation on various samples utilizing the SEM. Critical Point Drying (CPD) and metal coating with the sputter coater was followed before observing some cultured specimen and the samples that were soft in textures with high water content. SEM Top allowed investigating the detailed morphological features that can be used for classroom teaching. Undergraduate and graduate researchers studied biological samples of Arthropods, pollen grains and teeth collected from four species of snakes using SEM. This project inspired the research students to pursue their career in higher studies in science and 45% of the undergraduates participated in this project entered Graduate school.

Myofibroblasts in interstitial lung diseases show diverse electron microscopic and invasive features.

PubMed

Karvonen, Henna M; Lehtonen, Siri T; Sormunen, Raija T; Harju, Terttu H; Lappi-Blanco, Elisa; Bloigu, Risto S; Kaarteenaho, Riitta L

2012-09-01

The characteristic features of myofibroblasts in various lung disorders are poorly understood. We have evaluated the ultrastructure and invasive capacities of myofibroblasts cultured from small volumes of diagnostic bronchoalveolar lavage (BAL) fluid samples from patients with different types of lung diseases. Cells were cultured from samples of BAL fluid collected from 51 patients that had undergone bronchoscopy and BAL for diagnostic purposes. The cells were visualized by transmission electron microscopy and immunoelectron microscopy to achieve ultrastructural localization of alpha-smooth muscle actin (α-SMA) and fibronectin. The levels of α-SMA protein and mRNA and fibronectin mRNA were measured by western blot and quantitative real-time reverse transcriptase polymerase chain reaction. The invasive capacities of the cells were evaluated. The cultured cells were either fibroblasts or myofibroblasts. The structure of the fibronexus, and the amounts of intracellular actin, extracellular fibronectin and cell junctions of myofibroblasts varied in different diseases. In electron and immunoelectron microscopy, cells cultured from interstitial lung diseases (ILDs) expressed more actin filaments and α-SMA than normal lung. The invasive capacity of the cells obtained from patients with idiopathic pulmonary fibrosis was higher than that from patients with other type of ILDs. Cells expressing more actin filaments had a higher invasion capacity. It is concluded that electron and immunoelectron microscopic studies of myofibroblasts can reveal differential features in various diseases. An analysis of myofibroblasts cultured from diagnostic BAL fluid samples may represent a new kind of tool for diagnostics and research into lung diseases.

Transmission electron microscope studies of extraterrestrial materials

NASA Technical Reports Server (NTRS)

Keller, Lindsay P.

1995-01-01

Transmission Electron Microscopy, X-Ray spectrometry and electron-energy-loss spectroscopy are used to analyse carbon in interplanetary dust particles. Optical micrographs are shown depicting cross sections of the dust particles embedded in sulphur. Selected-area electron diffraction patterns are shown. Transmission Electron Microscope specimens of lunar soil were prepared using two methods: ion-milling and ultramicrotomy. A combination of high resolution TEM imaging and electron diffraction is used to characterize the opaque assemblages. The opaque assemblages analyzed in this study are dominated by ilmenite with lesser rutile and spinel exsolutions, and traces of Fe metal.

Superconductivity in compensated and uncompensated semiconductors.

PubMed

Yanase, Youichi; Yorozu, Naoyuki

2008-12-01

We investigate the localization and superconductivity in heavily doped semiconductors. The crossover from the superconductivity in the host band to that in the impurity band is described on the basis of the disordered three-dimensional attractive Hubbard model for binary alloys. The microscopic inhomogeneity and the thermal superconducting fluctuation are taken into account using the self-consistent 1-loop order theory. The superconductor-insulator transition accompanies the crossover from the host band to the impurity band. We point out an enhancement of the critical temperature T c around the crossover. Further localization of electron wave functions leads to the localization of Cooper pairs and induces the pseudogap. We find that both the doping compensation by additional donors and the carrier increase by additional acceptors suppress the superconductivity. A theoretical interpretation is proposed for the superconductivity in the boron-doped diamond, SiC, and Si.

Superconductivity in compensated and uncompensated semiconductors

PubMed Central

Yanase, Youichi; Yorozu, Naoyuki

2008-01-01

We investigate the localization and superconductivity in heavily doped semiconductors. The crossover from the superconductivity in the host band to that in the impurity band is described on the basis of the disordered three-dimensional attractive Hubbard model for binary alloys. The microscopic inhomogeneity and the thermal superconducting fluctuation are taken into account using the self-consistent 1-loop order theory. The superconductor-insulator transition accompanies the crossover from the host band to the impurity band. We point out an enhancement of the critical temperature Tc around the crossover. Further localization of electron wave functions leads to the localization of Cooper pairs and induces the pseudogap. We find that both the doping compensation by additional donors and the carrier increase by additional acceptors suppress the superconductivity. A theoretical interpretation is proposed for the superconductivity in the boron-doped diamond, SiC, and Si. PMID:27878018

Microscopic neural image registration based on the structure of mitochondria

NASA Astrophysics Data System (ADS)

Cao, Huiwen; Han, Hua; Rao, Qiang; Xiao, Chi; Chen, Xi

2017-02-01

Microscopic image registration is a key component of the neural structure reconstruction with serial sections of neural tissue. The goal of microscopic neural image registration is to recover the 3D continuity and geometrical properties of specimen. During image registration, various distortions need to be corrected, including image rotation, translation, tissue deformation et.al, which come from the procedure of sample cutting, staining and imaging. Furthermore, there is only certain similarity between adjacent sections, and the degree of similarity depends on local structure of the tissue and the thickness of the sections. These factors make the microscopic neural image registration a challenging problem. To tackle the difficulty of corresponding landmarks extraction, we introduce a novel image registration method for Scanning Electron Microscopy (SEM) images of serial neural tissue sections based on the structure of mitochondria. The ellipsoidal shape of mitochondria ensures that the same mitochondria has similar shape between adjacent sections, and its characteristic of broad distribution in the neural tissue guarantees that landmarks based on the mitochondria distributed widely in the image. The proposed image registration method contains three parts: landmarks extraction between adjacent sections, corresponding landmarks matching and image deformation based on the correspondences. We demonstrate the performance of our method with SEM images of drosophila brain.

Accurate Virus Quantitation Using a Scanning Transmission Electron Microscopy (STEM) Detector in a Scanning Electron Microscope

DTIC Science & Technology

2017-06-29

Accurate Virus Quantitation Using a Scanning Transmission Electron Microscopy (STEM) Detector in a Scanning Electron Microscope Candace D Blancett1...L Norris2, Cynthia A Rossi4 , Pamela J Glass3, Mei G Sun1,* 1 Pathology Division, United States Army Medical Research Institute of Infectious...Diseases (USAMRIID), 1425 Porter Street, Fort Detrick, Maryland, 21702 2Biostatistics Division, United States Army Medical Research Institute of

Damage-free vibrational spectroscopy of biological materials in the electron microscope

PubMed Central

Rez, Peter; Aoki, Toshihiro; March, Katia; Gur, Dvir; Krivanek, Ondrej L.; Dellby, Niklas; Lovejoy, Tracy C.; Wolf, Sharon G.; Cohen, Hagai

2016-01-01

Vibrational spectroscopy in the electron microscope would be transformative in the study of biological samples, provided that radiation damage could be prevented. However, electron beams typically create high-energy excitations that severely accelerate sample degradation. Here this major difficulty is overcome using an ‘aloof' electron beam, positioned tens of nanometres away from the sample: high-energy excitations are suppressed, while vibrational modes of energies <1 eV can be ‘safely' investigated. To demonstrate the potential of aloof spectroscopy, we record electron energy loss spectra from biogenic guanine crystals in their native state, resolving their characteristic C–H, N–H and C=O vibrational signatures with no observable radiation damage. The technique opens up the possibility of non-damaging compositional analyses of organic functional groups, including non-crystalline biological materials, at a spatial resolution of ∼10 nm, simultaneously combined with imaging in the electron microscope. PMID:26961578

Damage-free vibrational spectroscopy of biological materials in the electron microscope.

PubMed

Rez, Peter; Aoki, Toshihiro; March, Katia; Gur, Dvir; Krivanek, Ondrej L; Dellby, Niklas; Lovejoy, Tracy C; Wolf, Sharon G; Cohen, Hagai

2016-03-10

Vibrational spectroscopy in the electron microscope would be transformative in the study of biological samples, provided that radiation damage could be prevented. However, electron beams typically create high-energy excitations that severely accelerate sample degradation. Here this major difficulty is overcome using an 'aloof' electron beam, positioned tens of nanometres away from the sample: high-energy excitations are suppressed, while vibrational modes of energies <1 eV can be 'safely' investigated. To demonstrate the potential of aloof spectroscopy, we record electron energy loss spectra from biogenic guanine crystals in their native state, resolving their characteristic C-H, N-H and C=O vibrational signatures with no observable radiation damage. The technique opens up the possibility of non-damaging compositional analyses of organic functional groups, including non-crystalline biological materials, at a spatial resolution of ∼10 nm, simultaneously combined with imaging in the electron microscope.

Damage-free vibrational spectroscopy of biological materials in the electron microscope

DOE PAGES

Rez, Peter; Aoki, Toshihiro; March, Katia; ...

2016-03-10

Vibrational spectroscopy in the electron microscope would be transformative in the study of biological samples, provided that radiation damage could be prevented. However, electron beams typically create high-energy excitations that severely accelerate sample degradation. Here this major difficulty is overcome using an ‘aloof’ electron beam, positioned tens of nanometres away from the sample: high-energy excitations are suppressed, while vibrational modes of energies o1 eV can be ‘safely’ investigated. To demonstrate the potential of aloof spectroscopy, we record electron energy loss spectra from biogenic guanine crystals in their native state, resolving their characteristic C–H, N–H and C=O vibrational signatures with nomore » observable radiation damage. Furthermore, the technique opens up the possibility of non-damaging compositional analyses of organic functional groups, including non-crystalline biological materials, at a spatial resolution of ~10nm, simultaneously combined with imaging in the electron microscope.« less

Damage-free vibrational spectroscopy of biological materials in the electron microscope

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rez, Peter; Aoki, Toshihiro; March, Katia

Vibrational spectroscopy in the electron microscope would be transformative in the study of biological samples, provided that radiation damage could be prevented. However, electron beams typically create high-energy excitations that severely accelerate sample degradation. Here this major difficulty is overcome using an ‘aloof’ electron beam, positioned tens of nanometres away from the sample: high-energy excitations are suppressed, while vibrational modes of energies o1 eV can be ‘safely’ investigated. To demonstrate the potential of aloof spectroscopy, we record electron energy loss spectra from biogenic guanine crystals in their native state, resolving their characteristic C–H, N–H and C=O vibrational signatures with nomore » observable radiation damage. Furthermore, the technique opens up the possibility of non-damaging compositional analyses of organic functional groups, including non-crystalline biological materials, at a spatial resolution of ~10nm, simultaneously combined with imaging in the electron microscope.« less

Comprehensive Characterization of Extended Defects in Semiconductor Materials by a Scanning Electron Microscope.

PubMed

Hieckmann, Ellen; Nacke, Markus; Allardt, Matthias; Bodrov, Yury; Chekhonin, Paul; Skrotzki, Werner; Weber, Jörg

2016-05-28

Extended defects such as dislocations and grain boundaries have a strong influence on the performance of microelectronic devices and on other applications of semiconductor materials. However, it is still under debate how the defect structure determines the band structure, and therefore, the recombination behavior of electron-hole pairs responsible for the optical and electrical properties of the extended defects. The present paper is a survey of procedures for the spatially resolved investigation of structural and of physical properties of extended defects in semiconductor materials with a scanning electron microscope (SEM). Representative examples are given for crystalline silicon. The luminescence behavior of extended defects can be investigated by cathodoluminescence (CL) measurements. They are particularly valuable because spectrally and spatially resolved information can be obtained simultaneously. For silicon, with an indirect electronic band structure, CL measurements should be carried out at low temperatures down to 5 K due to the low fraction of radiative recombination processes in comparison to non-radiative transitions at room temperature. For the study of the electrical properties of extended defects, the electron beam induced current (EBIC) technique can be applied. The EBIC image reflects the local distribution of defects due to the increased charge-carrier recombination in their vicinity. The procedure for EBIC investigations is described for measurements at room temperature and at low temperatures. Internal strain fields arising from extended defects can be determined quantitatively by cross-correlation electron backscatter diffraction (ccEBSD). This method is challenging because of the necessary preparation of the sample surface and because of the quality of the diffraction patterns which are recorded during the mapping of the sample. The spatial resolution of the three experimental techniques is compared.

Comprehensive Characterization of Extended Defects in Semiconductor Materials by a Scanning Electron Microscope

PubMed Central

Hieckmann, Ellen; Nacke, Markus; Allardt, Matthias; Bodrov, Yury; Chekhonin, Paul; Skrotzki, Werner; Weber, Jörg

2016-01-01

Extended defects such as dislocations and grain boundaries have a strong influence on the performance of microelectronic devices and on other applications of semiconductor materials. However, it is still under debate how the defect structure determines the band structure, and therefore, the recombination behavior of electron-hole pairs responsible for the optical and electrical properties of the extended defects. The present paper is a survey of procedures for the spatially resolved investigation of structural and of physical properties of extended defects in semiconductor materials with a scanning electron microscope (SEM). Representative examples are given for crystalline silicon. The luminescence behavior of extended defects can be investigated by cathodoluminescence (CL) measurements. They are particularly valuable because spectrally and spatially resolved information can be obtained simultaneously. For silicon, with an indirect electronic band structure, CL measurements should be carried out at low temperatures down to 5 K due to the low fraction of radiative recombination processes in comparison to non-radiative transitions at room temperature. For the study of the electrical properties of extended defects, the electron beam induced current (EBIC) technique can be applied. The EBIC image reflects the local distribution of defects due to the increased charge-carrier recombination in their vicinity. The procedure for EBIC investigations is described for measurements at room temperature and at low temperatures. Internal strain fields arising from extended defects can be determined quantitatively by cross-correlation electron backscatter diffraction (ccEBSD). This method is challenging because of the necessary preparation of the sample surface and because of the quality of the diffraction patterns which are recorded during the mapping of the sample. The spatial resolution of the three experimental techniques is compared. PMID:27285177

U-10Mo Sample Preparation and Examination using Optical and Scanning Electron Microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prabhakaran, Ramprashad; Joshi, Vineet V.; Rhodes, Mark A.

2016-10-01

The purpose of this document is to provide guidelines to prepare specimens of uranium alloyed with 10 weight percent molybdenum (U-10Mo) for optical metallography and scanning electron microscopy. This document also provides instructions to set up an optical microscope and a scanning electron microscope to analyze U-10Mo specimens and to obtain the required information.

U-10Mo Sample Preparation and Examination using Optical and Scanning Electron Microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prabhakaran, Ramprashad; Joshi, Vineet V.; Rhodes, Mark A.

2016-03-30

The purpose of this document is to provide guidelines to prepare specimens of uranium alloyed with 10 weight percent molybdenum (U-10Mo) for optical metallography and scanning electron microscopy. This document also provides instructions to set up an optical microscope and a scanning electron microscope to analyze U-10Mo specimens and to obtain the required information.

A Student-Built Scanning Tunneling Microscope

ERIC Educational Resources Information Center

Ekkens, Tom

2015-01-01

Many introductory and nanotechnology textbooks discuss the operation of various microscopes including atomic force (AFM), scanning tunneling (STM), and scanning electron microscopes (SEM). In a nanotechnology laboratory class, students frequently utilize microscopes to obtain data without a thought about the detailed operation of the tool itself.…

78 FR 2659 - Application(s) for Duty-Free Entry of Scientific Instruments

Federal Register 2010, 2011, 2012, 2013, 2014

2013-01-14

..., 2201 West End Ave., Nashville, TN 37235. Instrument: Electron Microscope. Manufacturer: FEI Company... St., West Lafayette, IN 47907-2024. Instrument: Electron Microscope. Manufacturer: FEI Company, the..., microorganisms, nanomaterials, and chemical compounds. Justification for Duty-Free Entry: There are no...

Nanoforging Single Layer MoSe 2 Through Defect Engineering with Focused Helium Ion Beams

DOE PAGES

Iberi, Vighter; Liang, Liangbo; Ievlev, Anton V.; ...

2016-08-02

Development of devices and structures based on the layered 2D materials critically hinges on the capability to induce, control, and tailor the electronic, transport, and optoelectronic properties via defect engineering, much like doping strategies have enabled semiconductor electronics and forging enabled introduction of iron age. Here, we demonstrate the use of a scanning helium ion microscope (HIM) for tailoring the functionality of single layer MoSe 2 locally, and decipher associated mechanisms at atomic level. We demonstrate He + beam bombardment that locally creates vacancies, shifts the Fermi energy landscape and thereby increases the Young s modulus of elasticity. Furthermore, wemore » observe for the first time, an increase in the B-exciton photoluminescence signal from the nanoforged regions at room temperature. In conclusion, the approach for precise defect engineering demonstrated here opens opportunities for creating functional 2D optoelectronic devices with a wide range of customizable properties that include operating in the visible region.« less

Nanoforging Single Layer MoSe 2 Through Defect Engineering with Focused Helium Ion Beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Iberi, Vighter; Liang, Liangbo; Ievlev, Anton V.

Development of devices and structures based on the layered 2D materials critically hinges on the capability to induce, control, and tailor the electronic, transport, and optoelectronic properties via defect engineering, much like doping strategies have enabled semiconductor electronics and forging enabled introduction of iron age. Here, we demonstrate the use of a scanning helium ion microscope (HIM) for tailoring the functionality of single layer MoSe 2 locally, and decipher associated mechanisms at atomic level. We demonstrate He + beam bombardment that locally creates vacancies, shifts the Fermi energy landscape and thereby increases the Young s modulus of elasticity. Furthermore, wemore » observe for the first time, an increase in the B-exciton photoluminescence signal from the nanoforged regions at room temperature. In conclusion, the approach for precise defect engineering demonstrated here opens opportunities for creating functional 2D optoelectronic devices with a wide range of customizable properties that include operating in the visible region.« less

Nanoforging Single Layer MoSe2 Through Defect Engineering with Focused Helium Ion Beams

NASA Astrophysics Data System (ADS)

Iberi, Vighter; Liang, Liangbo; Ievlev, Anton V.; Stanford, Michael G.; Lin, Ming-Wei; Li, Xufan; Mahjouri-Samani, Masoud; Jesse, Stephen; Sumpter, Bobby G.; Kalinin, Sergei V.; Joy, David C.; Xiao, Kai; Belianinov, Alex; Ovchinnikova, Olga S.

2016-08-01

Development of devices and structures based on the layered 2D materials critically hinges on the capability to induce, control, and tailor the electronic, transport, and optoelectronic properties via defect engineering, much like doping strategies have enabled semiconductor electronics and forging enabled introduction the of iron age. Here, we demonstrate the use of a scanning helium ion microscope (HIM) for tailoring the functionality of single layer MoSe2 locally, and decipher associated mechanisms at the atomic level. We demonstrate He+ beam bombardment that locally creates vacancies, shifts the Fermi energy landscape and increases the Young’s modulus of elasticity. Furthermore, we observe for the first time, an increase in the B-exciton photoluminescence signal from the nanoforged regions at the room temperature. The approach for precise defect engineering demonstrated here opens opportunities for creating functional 2D optoelectronic devices with a wide range of customizable properties that include operating in the visible region.

Electron Localization in Molecular Fragmentation of H{sub 2} by Carrier-Envelope Phase Stabilized Laser Pulses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kremer, Manuel; Fischer, Bettina; Feuerstein, Bernold

2009-11-20

Fully differential data for H{sub 2} dissociation in ultrashort (6 fs, 760 nm), linearly polarized, intense (0.44 PW/cm{sup 2}) laser pulses with a stabilized carrier-envelope phase (CEP) were recorded with a reaction microscope. Depending on the CEP, the molecular orientation, and the kinetic energy release (KER), we find asymmetric proton emission at low KERs (0-3 eV), basically predicted by Roudnev and Esry, and much stronger than reported by Kling et al. Wave packet propagation calculations reproduce the salient features and discard, together with the observed KER-independent electron asymmetry, the first ionization step to be the reason for the asymmetric protonmore » emission.« less

Spatial modulation of above-the-gap cathodoluminescence in InP nanowires

NASA Astrophysics Data System (ADS)

Tizei, L. H. G.; Zagonel, L. F.; Tencé, M.; Stéphan, O.; Kociak, M.; Chiaramonte, T.; Ugarte, D.; Cotta, M. A.

2013-12-01

We report the observation of light emission on wurtzite InP nanowires excited by fast electrons. The experiments were performed in a scanning transmission electron microscope using an in-house-built cathodoluminescence detector. Besides the exciton emission, at 850 nm, emission above the band gap from 400 to 800 nm was observed. In particular, this broad emission presented systematic periodic modulations indicating variations in the local excitation probability. The physical origin of the detected emission is not clear. Measurements of the spatial variation of the above-the-gap emission points to the formation of leaky cavity modes of a plasmonic nature along the nanowire length, indicating the wave nature of the excitation. We propose a phenomenological model, which fits closely the observed spatial variations.

Generation of dense statistical connectomes from sparse morphological data

PubMed Central

Egger, Robert; Dercksen, Vincent J.; Udvary, Daniel; Hege, Hans-Christian; Oberlaender, Marcel

2014-01-01

Sensory-evoked signal flow, at cellular and network levels, is primarily determined by the synaptic wiring of the underlying neuronal circuitry. Measurements of synaptic innervation, connection probabilities and subcellular organization of synaptic inputs are thus among the most active fields of research in contemporary neuroscience. Methods to measure these quantities range from electrophysiological recordings over reconstructions of dendrite-axon overlap at light-microscopic levels to dense circuit reconstructions of small volumes at electron-microscopic resolution. However, quantitative and complete measurements at subcellular resolution and mesoscopic scales to obtain all local and long-range synaptic in/outputs for any neuron within an entire brain region are beyond present methodological limits. Here, we present a novel concept, implemented within an interactive software environment called NeuroNet, which allows (i) integration of sparsely sampled (sub)cellular morphological data into an accurate anatomical reference frame of the brain region(s) of interest, (ii) up-scaling to generate an average dense model of the neuronal circuitry within the respective brain region(s) and (iii) statistical measurements of synaptic innervation between all neurons within the model. We illustrate our approach by generating a dense average model of the entire rat vibrissal cortex, providing the required anatomical data, and illustrate how to measure synaptic innervation statistically. Comparing our results with data from paired recordings in vitro and in vivo, as well as with reconstructions of synaptic contact sites at light- and electron-microscopic levels, we find that our in silico measurements are in line with previous results. PMID:25426033

Tunneling rates in electron transport through double-barrier molecular junctions in a scanning tunneling microscope

PubMed Central

Nazin, G. V.; Wu, S. W.; Ho, W.

2005-01-01

The scanning tunneling microscope enables atomic-scale measurements of electron transport through individual molecules. Copper phthalocyanine and magnesium porphine molecules adsorbed on a thin oxide film grown on the NiAl(110) surface were probed. The single-molecule junctions contained two tunneling barriers, vacuum gap, and oxide film. Differential conductance spectroscopy shows that electron transport occurs via vibronic states of the molecules. The intensity of spectral peaks corresponding to the individual vibronic states depends on the relative electron tunneling rates through the two barriers of the junction, as found by varying the vacuum gap tunneling rate by changing the height of the scanning tunneling microscope tip above the molecule. A simple, sequential tunneling model explains the observed trends. PMID:15956189

Tunneling rates in electron transport through double-barrier molecular junctions in a scanning tunneling microscope.

PubMed

Nazin, G V; Wu, S W; Ho, W

2005-06-21

The scanning tunneling microscope enables atomic-scale measurements of electron transport through individual molecules. Copper phthalocyanine and magnesium porphine molecules adsorbed on a thin oxide film grown on the NiAl(110) surface were probed. The single-molecule junctions contained two tunneling barriers, vacuum gap, and oxide film. Differential conductance spectroscopy shows that electron transport occurs via vibronic states of the molecules. The intensity of spectral peaks corresponding to the individual vibronic states depends on the relative electron tunneling rates through the two barriers of the junction, as found by varying the vacuum gap tunneling rate by changing the height of the scanning tunneling microscope tip above the molecule. A simple, sequential tunneling model explains the observed trends.

A high-resolution combined scanning laser and widefield polarizing microscope for imaging at temperatures from 4 K to 300 K.

PubMed

Lange, M; Guénon, S; Lever, F; Kleiner, R; Koelle, D

2017-12-01

Polarized light microscopy, as a contrast-enhancing technique for optically anisotropic materials, is a method well suited for the investigation of a wide variety of effects in solid-state physics, as, for example, birefringence in crystals or the magneto-optical Kerr effect (MOKE). We present a microscopy setup that combines a widefield microscope and a confocal scanning laser microscope with polarization-sensitive detectors. By using a high numerical aperture objective, a spatial resolution of about 240 nm at a wavelength of 405 nm is achieved. The sample is mounted on a 4 He continuous flow cryostat providing a temperature range between 4 K and 300 K, and electromagnets are used to apply magnetic fields of up to 800 mT with variable in-plane orientation and 20 mT with out-of-plane orientation. Typical applications of the polarizing microscope are the imaging of the in-plane and out-of-plane magnetization via the longitudinal and polar MOKE, imaging of magnetic flux structures in superconductors covered with a magneto-optical indicator film via the Faraday effect, or imaging of structural features, such as twin-walls in tetragonal SrTiO 3 . The scanning laser microscope furthermore offers the possibility to gain local information on electric transport properties of a sample by detecting the beam-induced voltage change across a current-biased sample. This combination of magnetic, structural, and electric imaging capabilities makes the microscope a viable tool for research in the fields of oxide electronics, spintronics, magnetism, and superconductivity.

A high-resolution combined scanning laser and widefield polarizing microscope for imaging at temperatures from 4 K to 300 K

NASA Astrophysics Data System (ADS)

Lange, M.; Guénon, S.; Lever, F.; Kleiner, R.; Koelle, D.

2017-12-01

Polarized light microscopy, as a contrast-enhancing technique for optically anisotropic materials, is a method well suited for the investigation of a wide variety of effects in solid-state physics, as, for example, birefringence in crystals or the magneto-optical Kerr effect (MOKE). We present a microscopy setup that combines a widefield microscope and a confocal scanning laser microscope with polarization-sensitive detectors. By using a high numerical aperture objective, a spatial resolution of about 240 nm at a wavelength of 405 nm is achieved. The sample is mounted on a 4He continuous flow cryostat providing a temperature range between 4 K and 300 K, and electromagnets are used to apply magnetic fields of up to 800 mT with variable in-plane orientation and 20 mT with out-of-plane orientation. Typical applications of the polarizing microscope are the imaging of the in-plane and out-of-plane magnetization via the longitudinal and polar MOKE, imaging of magnetic flux structures in superconductors covered with a magneto-optical indicator film via the Faraday effect, or imaging of structural features, such as twin-walls in tetragonal SrTiO3. The scanning laser microscope furthermore offers the possibility to gain local information on electric transport properties of a sample by detecting the beam-induced voltage change across a current-biased sample. This combination of magnetic, structural, and electric imaging capabilities makes the microscope a viable tool for research in the fields of oxide electronics, spintronics, magnetism, and superconductivity.

Preservation of capsular material of streptococcal cells by specific lectins determined by immunoelectron microscopy.

PubMed

Molinari, A; Orefici, G; Donelli, G; Von Hunolstein, C; Paradisi, S; Arancia, G

1988-09-01

We describe the use of lectins as specific stabilizing agents for the polysaccharide capsular components of two Gram-positive bacteria, Streptococcus agalactiae and Streptococcus bovis. Treatment of bacterial suspensions with wheatgerm agglutinin and concanavalin A allowed better morphological preservation as well as immunoelectron microscopic localization of a capsular component (lipoteichoic acid) by employing specific antibodies and the protein A-gold technique. Data obtained indicate that lectins are useful agents in preserving highly water-soluble capsular components during the electron microscopy procedures for both unembedded and embedded samples.

Localized Surface Plasmon Resonance of Metal Nanodot Nanowire Arrays Studied by Far-Field and Near-Field Optical

DTIC Science & Technology

2007-09-05

microscope, nanoholes or nanogrooves can be created on the film. After coating a thin Au film by electron beam evaporation and soaking the sample in acetone...SNOM. III. Results and Discussion: (a) LSPR of Au Nanodots With the use of an indentation force of 3.8 μN, a nanohole array was generated on the...images of (a) a nanohole array on PMMA and (b) the corresponding Au nanodot array after lift-off. SEM images of (c) a Au nanodot pattern “NANO” on

Transport characteristics in Au/pentacene/Au diodes

NASA Astrophysics Data System (ADS)

Hayashi, Toshiaki; Naka, Akiyoshi; Hiroki, Masanobu; Yokota, Tomoyuki; Someya, Takao; Fujiwara, Akira

2018-03-01

We have used scanning and transmission electron microscopes (SEM and TEM) to study the structure of a pentacene thin film grown on a Au layer with and shown that it consists of randomly oriented amorphous pentacene clusters. We have also investigated the transport properties of amorphous pentacene in a metal-semiconductor-metal (MSM) diode structure and shown that the current is logarithmically proportional to the square root of the applied voltage, which indicates that transport occurs as the result of hopping between localized sites randomly distributed in space and energy.

Origin of the different transport properties of electron and hole polarons in an ambipolar polyselenophene-based conjugated polymer

NASA Astrophysics Data System (ADS)

Chen, Zhuoying; Bird, Matthew; Lemaur, Vincent; Radtke, Guillaume; Cornil, Jérôme; Heeney, Martin; McCulloch, Iain; Sirringhaus, Henning

2011-09-01

Understanding the mechanisms limiting ambipolar transport in conjugated polymer field-effect transistors (FETs) is of both fundamental and practical interest. Here, we present a systematic study comparing hole and electron charge transport in an ambipolar conjugated polymer, semicrystalline poly(3,3''-di-n-decylterselenophene) (PSSS). Starting from a detailed analysis of the device characteristics and temperature/charge-density dependence of the mobility, we interpret the difference between hole and electron transport through both the Vissenberg-Matters and the mobility-edge model. To obtain microscopic insight into the quantum mechanical wave function of the charges at a molecular level, we combine charge modulation spectroscopy (CMS) measuring the charge-induced absorption signatures from positive and negative polarons in these ambipolar FETs with corresponding density functional theory (DFT) calculations. We observe a significantly higher switch-on voltage for electrons than for holes due to deep electron trap states, but also a higher activation energy of the mobility for mobile electrons. The CMS spectra reveal that the electrons that remain mobile and contribute to the FET current have a wave function that is more localized onto a single polymer chain than that of holes, which is extended over several polymer chains. We interpret this as evidence that the transport properties of the mobile electrons in PSSS are still affected by the presence of deep electron traps. The more localized electron state could be due to the mobile electrons interacting with shallow trap states in the vicinity of a chemical, potentially water-related, impurity that might precede the capture of the electron into a deeply trapped state.

Microcellular nanocomposite injection molding process

Treesearch

Mingjun Yuan; Lih-Sheng Turng; Rick Spindler; Daniel Caulfield; Chris Hunt

2003-01-01

This study aims to explore the processing benefits and property improvements of combining nanocomposites with microcellular injection molding. The molded parts produced based on the Design of Experiments (DOE) matrices were subjected to tensile testing, impact testing, and Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), Dynamic Mechanical...

The microscopic world: A demonstration of electron microscopy for younger students

NASA Technical Reports Server (NTRS)

Horton, Linda L.

1992-01-01

The purpose is to excite students about the importance of scientific investigation and demonstrate why they should look at things in greater detail, extending beyond superficial examination. The topics covered include: microscopy, scanning electron microscopes, high magnification, and the scientific method.

In situ structure and dynamics of DNA origami determined through molecular dynamics simulations

PubMed Central

Yoo, Jejoong; Aksimentiev, Aleksei

2013-01-01

The DNA origami method permits folding of long single-stranded DNA into complex 3D structures with subnanometer precision. Transmission electron microscopy, atomic force microscopy, and recently cryo-EM tomography have been used to characterize the properties of such DNA origami objects, however their microscopic structures and dynamics have remained unknown. Here, we report the results of all-atom molecular dynamics simulations that characterized the structural and mechanical properties of DNA origami objects in unprecedented microscopic detail. When simulated in an aqueous environment, the structures of DNA origami objects depart from their idealized targets as a result of steric, electrostatic, and solvent-mediated forces. Whereas the global structural features of such relaxed conformations conform to the target designs, local deformations are abundant and vary in magnitude along the structures. In contrast to their free-solution conformation, the Holliday junctions in the DNA origami structures adopt a left-handed antiparallel conformation. We find the DNA origami structures undergo considerable temporal fluctuations on both local and global scales. Analysis of such structural fluctuations reveals the local mechanical properties of the DNA origami objects. The lattice type of the structures considerably affects global mechanical properties such as bending rigidity. Our study demonstrates the potential of all-atom molecular dynamics simulations to play a considerable role in future development of the DNA origami field by providing accurate, quantitative assessment of local and global structural and mechanical properties of DNA origami objects. PMID:24277840

In situ structure and dynamics of DNA origami determined through molecular dynamics simulations.

PubMed

Yoo, Jejoong; Aksimentiev, Aleksei

2013-12-10

The DNA origami method permits folding of long single-stranded DNA into complex 3D structures with subnanometer precision. Transmission electron microscopy, atomic force microscopy, and recently cryo-EM tomography have been used to characterize the properties of such DNA origami objects, however their microscopic structures and dynamics have remained unknown. Here, we report the results of all-atom molecular dynamics simulations that characterized the structural and mechanical properties of DNA origami objects in unprecedented microscopic detail. When simulated in an aqueous environment, the structures of DNA origami objects depart from their idealized targets as a result of steric, electrostatic, and solvent-mediated forces. Whereas the global structural features of such relaxed conformations conform to the target designs, local deformations are abundant and vary in magnitude along the structures. In contrast to their free-solution conformation, the Holliday junctions in the DNA origami structures adopt a left-handed antiparallel conformation. We find the DNA origami structures undergo considerable temporal fluctuations on both local and global scales. Analysis of such structural fluctuations reveals the local mechanical properties of the DNA origami objects. The lattice type of the structures considerably affects global mechanical properties such as bending rigidity. Our study demonstrates the potential of all-atom molecular dynamics simulations to play a considerable role in future development of the DNA origami field by providing accurate, quantitative assessment of local and global structural and mechanical properties of DNA origami objects.

Overview about the localization of nanoparticles in tissue and cellular context by different imaging techniques

PubMed Central

Ostrowski, Anja; Nordmeyer, Daniel; Boreham, Alexander; Holzhausen, Cornelia; Mundhenk, Lars; Graf, Christina; Meinke, Martina C; Vogt, Annika; Hadam, Sabrina; Lademann, Jürgen; Rühl, Eckart; Alexiev, Ulrike

2015-01-01

Summary The increasing interest and recent developments in nanotechnology pose previously unparalleled challenges in understanding the effects of nanoparticles on living tissues. Despite significant progress in in vitro cell and tissue culture technologies, observations on particle distribution and tissue responses in whole organisms are still indispensable. In addition to a thorough understanding of complex tissue responses which is the domain of expert pathologists, the localization of particles at their sites of interaction with living structures is essential to complete the picture. In this review we will describe and compare different imaging techniques for localizing inorganic as well as organic nanoparticles in tissues, cells and subcellular compartments. The visualization techniques include well-established methods, such as standard light, fluorescence, transmission electron and scanning electron microscopy as well as more recent developments, such as light and electron microscopic autoradiography, fluorescence lifetime imaging, spectral imaging and linear unmixing, superresolution structured illumination, Raman microspectroscopy and X-ray microscopy. Importantly, all methodologies described allow for the simultaneous visualization of nanoparticles and evaluation of cell and tissue changes that are of prime interest for toxicopathologic studies. However, the different approaches vary in terms of applicability for specific particles, sensitivity, optical resolution, technical requirements and thus availability, and effects of labeling on particle properties. Specific bottle necks of each technology are discussed in detail. Interpretation of particle localization data from any of these techniques should therefore respect their specific merits and limitations as no single approach combines all desired properties. PMID:25671170

UK114, a YjgF/Yer057p/UK114 family protein highly conserved from bacteria to mammals, is localized in rat liver peroxisomes.

PubMed

Antonenkov, Vasily D; Ohlmeier, Steffen; Sormunen, Raija T; Hiltunen, J Kalervo

2007-05-25

Mammalian UK114 belongs to a highly conserved family of proteins with unknown functions. Although it is believed that UK114 is a cytosolic or mitochondrial protein there is no detailed study of its intracellular localization. Using analytical subcellular fractionation, electron microscopic colloidal gold technique, and two-dimensional gel electrophoresis of peroxisomal matrix proteins combined with mass spectrometric analysis we show here that a large portion of UK114 is present in rat liver peroxisomes. The peroxisomal UK114 is a soluble matrix protein and it is not inducible by the peroxisomal proliferator clofibrate. The data predict involvement of UK114 in peroxisomal metabolism.

Correlation between Charge Contrast Imaging and the Distribution of Some Trace Level Impurities in Gibbsite

NASA Astrophysics Data System (ADS)

Baroni, Travis C.; Griffin, Brendan J.; Browne, James R.; Lincoln, Frank J.

2000-01-01

Charge contrast images (CCI) of synthetic gibbsite obtained on an environmental scanning electron microscope gives information on the crystallization process. Furthermore, X-ray mapping of the same grains shows that impurities are localized during the initial stages of growth and that the resulting composition images have features similar to these observed in CCI. This suggests a possible correlation between impurity distributions and the emission detected during CCI. X-ray line profiles, simulating the spatial distribution of impurities derived from the Monte Carlo program CASINO, have been compared with experimental line profiles and give an estimate of the localization. The model suggests that a main impurity, Ca, is depleted from the solution within approximately 3 4 [mu]m of growth.

Study of plastic strain localization mechanisms caused by nonequilibrium transitions in mesodefect ensembles under high-speed loading

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sokovikov, Mikhail, E-mail: sokovikov@icmm.ru; Chudinov, Vasiliy; Bilalov, Dmitry

2015-10-27

The behavior of specimens dynamically loaded during split Hopkinson (Kolsky) bar tests in a regime close to simple shear conditions was studied. The lateral surface of the specimens was investigated in-situ using a high-speed infrared camera CEDIP Silver 450M. The temperature field distribution obtained at different time allowed one to trace the evolution of plastic strain localization. The process of target perforation involving plug formation and ejection was examined using a high-speed infrared camera and a VISAR velocity measurement system. The microstructure of tested specimens was analyzed using an optical interferometer-profiler and a scanning electron microscope. The development of plasticmore » shear instability regions has been simulated numerically.« less

Anomaly Detection in Nanofibrous Materials by CNN-Based Self-Similarity

PubMed Central

Schettini, Raimondo

2018-01-01

Automatic detection and localization of anomalies in nanofibrous materials help to reduce the cost of the production process and the time of the post-production visual inspection process. Amongst all the monitoring methods, those exploiting Scanning Electron Microscope (SEM) imaging are the most effective. In this paper, we propose a region-based method for the detection and localization of anomalies in SEM images, based on Convolutional Neural Networks (CNNs) and self-similarity. The method evaluates the degree of abnormality of each subregion of an image under consideration by computing a CNN-based visual similarity with respect to a dictionary of anomaly-free subregions belonging to a training set. The proposed method outperforms the state of the art. PMID:29329268

Scanning electron microscope studies of sea urchin fertilization. I. Eggs with vitelline layers.

PubMed

Tegner, M J; Epel, D

1976-07-01

The surface coats of sea urchin eggs and the events of fertilization which take place on these surfaces were examined with the scanning electron microscope (SEM). Gametes of Stronglyocentrotus purpuratus and Lytechinus pictus were considered in detail; eggs of seven other echinoids were examined for comparative purposes. Jelly coats, preserved by varying the pH of fixation, were found to vary in morphology and solubility properties between species. The vitelline layers of the nine echinoids are characterized by arrays of projections which are impressions of cytoplasmic microvilli in the vitelline layer. After sperm bind to the egg surface via the acrosomal process, fine filaments, apparently an egg response to insemination, further connect some sperm heads and tails to the egg. The cortical reactions spread out as a wave from where the fertilizing sperm fused with the egg; separation of the vitelline layer proceeds as a smooth wave from S. purpuratus eggs and as a series of localized separations in L. pictus eggs. The fertilization membranes of S. purpuratus and Allocentrotus fragilis zygotes are expanded replicas of their respective vitelline layers, suggesting that fertilization membranes are formed by an unfolding of the vitelline layer.

Direct Observation Through In Situ Transmission Electron Microscope of Early States of Crystallization in Nanoscale Metallic Glasses

NASA Astrophysics Data System (ADS)

Xie, Y.; Sohn, S.; Schroers, J.; Cha, J. J.

2017-11-01

Crystallization is a complex process that involves multiscale physics such as diffusion of atomic species over multiple length scales, thermodynamic energy considerations, and multiple possible intermediate states. In situ crystallization experiments inside a transmission electron microscope (TEM) using nanostructured metallic glasses (MGs) provide a unique platform to study directly crystallization kinetics and pathways. Here, we study the embryonic state of eutectic growth using Pt-Ni-Cu-P MG nanorods under in situ TEM. We directly observe the nucleation and growth of a Ni-rich polymorphic phase, followed by the nucleation and slower growth of a Cu-rich phase. The suppressed growth kinetics of the Cu-rich phase is attributed to locally changing chemical compositions. In addition, we show that growth can be controlled by incorporation of an entire nucleus instead of individual atoms. Such a nucleus has to align with the crystallographic orientation of a larger grain before it can be incorporated into the crystal. By directly observing the crystallization processes, particularly the early stages of non-polymorphic growth, in situ TEM crystallization studies of MG nanostructures provide a wealth of information, some of which can be applied to typical bulk crystallization.

Effects of gamma radiation on hard dental tissues of albino rats using scanning electron microscope - Part 1

NASA Astrophysics Data System (ADS)

El-Faramawy, Nabil; Ameen, Reham; El-Haddad, Khaled; Maghraby, Ahmed; El-Zainy, Medhat

2011-12-01

In the present study, 40 adult male albino rats were used to study the effect of gamma radiation on the hard dental tissues (enamel surface, dentinal tubules and the cementum surface). The rats were irradiated at 0.2, 0.5, 1.0, 2.0, 4.0 and 6.0 Gy gamma doses. The effects of irradiated hard dental tissues samples were investigated using a scanning electron microscope. For doses up to 0.5 Gy, there was no evidence of the existence of cracks on the enamel surface. With 1 Gy irradiation dose, cracks were clearly observed with localized erosive areas. At 2 Gy irradiation dose, the enamel showed morphological alterations as disturbed prismatic and interprismatic areas. An increase in dentinal tubules diameter and a contemporary inter-tubular dentine volume decrease were observed with higher irradiation dose. Concerning cementum, low doses,<0.5 Gy, showed surface irregularities and with increase in the irradiation dose to≥1 Gy, noticeable surface irregularities and erosive areas with decrease in Sharpey's fiber sites were observed. These observations could shed light on the hazardous effects of irradiation fields to the functioning of the human teeth.

Characterization and manipulation of individual defects in insulating hexagonal boron nitride using scanning tunnelling microscopy.

PubMed

Wong, Dillon; Velasco, Jairo; Ju, Long; Lee, Juwon; Kahn, Salman; Tsai, Hsin-Zon; Germany, Chad; Taniguchi, Takashi; Watanabe, Kenji; Zettl, Alex; Wang, Feng; Crommie, Michael F

2015-11-01

Defects play a key role in determining the properties and technological applications of nanoscale materials and, because they tend to be highly localized, characterizing them at the single-defect level is of particular importance. Scanning tunnelling microscopy has long been used to image the electronic structure of individual point defects in conductors, semiconductors and ultrathin films, but such single-defect electronic characterization remains an elusive goal for intrinsic bulk insulators. Here, we show that individual native defects in an intrinsic bulk hexagonal boron nitride insulator can be characterized and manipulated using a scanning tunnelling microscope. This would typically be impossible due to the lack of a conducting drain path for electrical current. We overcome this problem by using a graphene/boron nitride heterostructure, which exploits the atomically thin nature of graphene to allow the visualization of defect phenomena in the underlying bulk boron nitride. We observe three different defect structures that we attribute to defects within the bulk insulating boron nitride. Using scanning tunnelling spectroscopy we obtain charge and energy-level information for these boron nitride defect structures. We also show that it is possible to manipulate the defects through voltage pulses applied to the scanning tunnelling microscope tip.

Ion irradiation synthesis of Ag-Au bimetallic nanospheroids in SiO2 glass substrate with tunable surface plasmon resonance frequency

NASA Astrophysics Data System (ADS)

Meng, Xuan; Shibayama, Tamaki; Yu, Ruixuan; Takayanagi, Shinya; Watanabe, Seiichi

2013-08-01

Ag-Au bimetallic nanospheroids with tunable localized surface plasmon resonance (LSPR) were synthesized by 100 keV Ar-ion irradiation of 30 nm Ag-Au bimetallic films deposited on SiO2 glass substrates. A shift of the LSPR peaks toward shorter wavelengths was observed up to an irradiation fluence of 1.0 × 1017 cm-2, and then shifted toward the longer wavelength because of the increase of fragment volume under ion irradiation. Further control of LSPR frequency over a wider range was realized by modifying the chemical components. The resulting LSPR frequencies lie between that of the pure components, and an approximate linear shift of the LSPR toward the longer wavelength with the Au concentration was achieved, which is in good agreement with the theoretical calculations based on Gans theory. In addition, the surface morphology and compositions were examined with a scanning electron microscope equipped with an energy dispersive spectrometer, and microstructural characterizations were performed using a transmission electron microscope. The formation of isolated photosensitive Ag-Au nanospheroids with a FCC structure partially embedded in the SiO2 substrate was confirmed, which has a potential application in solid-state devices.

Nucleotide-Specific Contrast for DNA Sequencing by Electron Spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mankos, Marian; Persson, Henrik H. J.; N’Diaye, Alpha T.

DNA sequencing by imaging in an electron microscope is an approach that holds promise to deliver long reads with low error rates and without the need for amplification. Earlier work using transmission electron microscopes, which use high electron energies on the order of 100 keV, has shown that low contrast and radiation damage necessitates the use of heavy atom labeling of individual nucleotides, which increases the read error rates. Other prior work using scattering electrons with much lower energy has shown to suppress beam damage on DNA. Here we explore possibilities to increase contrast by employing two methods, X-ray photoelectronmore » and Auger electron spectroscopy. Using bulk DNA samples with monomers of each base, both methods are shown to provide contrast mechanisms that can distinguish individual nucleotides without labels. In conclusion, both spectroscopic techniques can be readily implemented in a low energy electron microscope, which may enable label-free DNA sequencing by direct imaging.« less

Nucleotide-Specific Contrast for DNA Sequencing by Electron Spectroscopy

DOE PAGES

Mankos, Marian; Persson, Henrik H. J.; N’Diaye, Alpha T.; ...

2016-05-05

DNA sequencing by imaging in an electron microscope is an approach that holds promise to deliver long reads with low error rates and without the need for amplification. Earlier work using transmission electron microscopes, which use high electron energies on the order of 100 keV, has shown that low contrast and radiation damage necessitates the use of heavy atom labeling of individual nucleotides, which increases the read error rates. Other prior work using scattering electrons with much lower energy has shown to suppress beam damage on DNA. Here we explore possibilities to increase contrast by employing two methods, X-ray photoelectronmore » and Auger electron spectroscopy. Using bulk DNA samples with monomers of each base, both methods are shown to provide contrast mechanisms that can distinguish individual nucleotides without labels. In conclusion, both spectroscopic techniques can be readily implemented in a low energy electron microscope, which may enable label-free DNA sequencing by direct imaging.« less

Knowledge Extraction from Atomically Resolved Images.

PubMed

Vlcek, Lukas; Maksov, Artem; Pan, Minghu; Vasudevan, Rama K; Kalinin, Sergei V

2017-10-24

Tremendous strides in experimental capabilities of scanning transmission electron microscopy and scanning tunneling microscopy (STM) over the past 30 years made atomically resolved imaging routine. However, consistent integration and use of atomically resolved data with generative models is unavailable, so information on local thermodynamics and other microscopic driving forces encoded in the observed atomic configurations remains hidden. Here, we present a framework based on statistical distance minimization to consistently utilize the information available from atomic configurations obtained from an atomically resolved image and extract meaningful physical interaction parameters. We illustrate the applicability of the framework on an STM image of a FeSe x Te 1-x superconductor, with the segregation of the chalcogen atoms investigated using a nonideal interacting solid solution model. This universal method makes full use of the microscopic degrees of freedom sampled in an atomically resolved image and can be extended via Bayesian inference toward unbiased model selection with uncertainty quantification.

Fano Description of Single-Hydrocarbon Fluorescence Excited by a Scanning Tunneling Microscope.

PubMed

Kröger, Jörg; Doppagne, Benjamin; Scheurer, Fabrice; Schull, Guillaume

2018-06-13

The detection of fluorescence with submolecular resolution enables the exploration of spatially varying photon yields and vibronic properties at the single-molecule level. By placing individual polycyclic aromatic hydrocarbon molecules into the plasmon cavity formed by the tip of a scanning tunneling microscope and a NaCl-covered Ag(111) surface, molecular light emission spectra are obtained that unravel vibrational progression. In addition, light spectra unveil a signature of the molecule even when the tunneling current is injected well separated from the molecular emitter. This signature exhibits a distance-dependent Fano profile that reflects the subtle interplay between inelastic tunneling electrons, the molecular exciton and localized plasmons in at-distance as well as on-molecule fluorescence. The presented findings open the path to luminescence of a different class of molecules than investigated before and contribute to the understanding of single-molecule luminescence at surfaces in a unified picture.

Time-resolved electric force microscopy of charge traps in polycrystalline pentacene films

NASA Astrophysics Data System (ADS)

Jaquith, Michael; Muller, Erik; Marohn, John

2006-03-01

The microscopic mechanisms by which charges trap in organic electronic materials are poorly understood. Muller and Marohn recently showed that electric force microscopy (EFM) can be used to image trapped charge in working pentacene thin-film transistors [E. M. Muller et al, Adv. Mater. 17 1410 (2005)]. We have extended their work by imaging trapped charge in pentacene films with much larger grains. In contrast to the previous study in which charge was found to trap inhomogeneously throughout the transistor gap, we find microscopic evidence for a new trapping mechanism in which charges trap predominantly at the pentacene/metal interface in large-grained devices. We have also made localized measurements of the trap growth over time by performing pulsed-gate EFM experiments. Integrated-rate kinetics data supports a charge trap mechanism which is second order in holes, e.g., holes trap in pairs, although the charge-trapping rate appears to depend on gate voltage.

A next generation positron microscope and a survey of candidate samples for future positron studies

NASA Astrophysics Data System (ADS)

Dull, Terry Lou

A positron microscope has been constructed and is nearing the conclusion of its assembly and testing. The instrument is designed to perform positron and electron microscopy in both scanning and magnifying modes. In scanning mode, a small beam of particles is rastered across the target and the amplitude of a positron or electron related signal is recorded as a function of position. For positrons this signal may come from Doppler Broadening Spectroscopy, Reemitted Positron Spectroscopy or Positron Annihilation Lifetime Spectroscopy. For electrons this signal may come from the number of secondary electrons or Auger Electron Spectroscopy. In magnifying mode an incident beam of particles is directed onto the target and emitted particles, either secondary electrons or reemitted positrons, are magnified to form an image. As a positron microscope the instrument will primarily operate in magnifying mode, as a positron reemission microscope. As an electron microscope the instrument will be able to operate in both magnifying and scanning modes. Depth-profiled Doppler Broadening Spectroscopy studies using a non-microscopic low-energy positron beam have also been performed on a series of samples to ascertain the applicability of positron spectroscopies and/or microscopy to their study. All samples have sub-micron film and/or feature size and thus are only susceptible to positron study with low-energy beams. Several stoichiometries and crystallinities of chalcogenide thin films (which can be optically reversibly switched between crystalline states) were studied and a correlation was found to exist between the amorphous/FCC S-parameter difference and the amorphous/FCC switching time. Amorphous silicon films were studied in an attempt to observe the well-established Staebler-Wronski effect as well as the more controversial photodilatation effect. However, DBS was not able to detect either effect. The passive oxide films on titanium and aluminum were studied in an attempt to verify the Point Defect Model, a detailed, but as yet microscopically unconfirmed, theory of the corrosive breakdown of passive films. DBS results supportive of the PDM were observed. Graphitic carbon fibers were also studied and DBS indicated the presence of a 200 nm thick outer fiber skin possibly characterized by a high degree of graphitic crystallite alignment.

Microscopic Electron Variations Measured Simultaneously By The Cluster Spacecraft

NASA Astrophysics Data System (ADS)

Buckley, A. M.; Carozzi, T. D.; Gough, M. P.; Beloff, N.

Data is used from the Particle Correlator experiments running on each of the four Cluster spacecraft so as to determine common microscopic behaviour in the elec- tron population observed over the macroscopic Cluster separations. The Cluster par- ticle correlator experiments operate by forming on board Auto Correlation Functions (ACFs) generated from short time series of electron counts obtained, as a function of electron energy, from the PEACE HEEA sensor. The information on the microscopic variation of the electron flux covers the frequency range DC up to 41 kHz (encom- passing typical electron plasma frequencies and electron gyro frequencies and their harmonics), the electron energy range is that covered by the PEACE HEEA sensor (within the range 1 eV to 26 keV). Results are presented of coherent electron struc- tures observed simultaneously by the four spacecraft in the differing plasma interac- tion regions and boundaries encountered by Cluster. As an aid to understanding the plasma interactions, use is made of numerical simulations which model both the un- derlying statistical properties of the electrons and also the manner in which particle correlator experiments operate.

Interference experiment with asymmetric double slit by using 1.2-MV field emission transmission electron microscope.

PubMed

Harada, Ken; Akashi, Tetsuya; Niitsu, Kodai; Shimada, Keiko; Ono, Yoshimasa A; Shindo, Daisuke; Shinada, Hiroyuki; Mori, Shigeo

2018-01-17

Advanced electron microscopy technologies have made it possible to perform precise double-slit interference experiments. We used a 1.2-MV field emission electron microscope providing coherent electron waves and a direct detection camera system enabling single-electron detections at a sub-second exposure time. We developed a method to perform the interference experiment by using an asymmetric double-slit fabricated by a focused ion beam instrument and by operating the microscope under a "pre-Fraunhofer" condition, different from the Fraunhofer condition of conventional double-slit experiments. Here, pre-Fraunhofer condition means that each single-slit observation was performed under the Fraunhofer condition, while the double-slit observations were performed under the Fresnel condition. The interference experiments with each single slit and with the asymmetric double slit were carried out under two different electron dose conditions: high-dose for calculation of electron probability distribution and low-dose for each single electron distribution. Finally, we exemplified the distribution of single electrons by color-coding according to the above three types of experiments as a composite image.

Pre-microscope tunnelling — Inspiration or constraint?

NASA Astrophysics Data System (ADS)

Walmsley, D. G.

1987-03-01

Before the microscope burst upon the scene, tunnelling had established for itself a substantial niche in the repertoire of the solid state physicist. Over a period of 20 years it has contributed importantly to our understanding of many systems. It elucidated the superconducting state, first by a direct display of the energy gap then by providing detailed information on the phonon spectra and electron-phonon coupling strength in junction electrodes. Its use as a phonon spectrometer was subsequently extended to semiconductors and to the oxides of insulating barriers. Eventually the vibrational spectra of monolayer organic and inorganic adsorbates became amenable with rich scientific rewards. In a few cases electronic transitions have been observed. Plasmon excitation by tunnelling electrons led to insights on the electron loss function in metals at visible frequencies and provided along the way an intriguing light emitting device. With the advent of the microscope it is now appropriate to enquire how much of this experience can profitably be carried over to the new environment. Are we constrained just to repeat the experiments in a new configuration? Happily no. The microscope offers us topographical and spectroscopic information of a new order. One might next ask how great is the contact between the two disciplines? We explore this question and seek to establish where the pre-microscope experience can be helpful in inspiring our use of this marvellous new facility that we know as the scanning tunnelling microscope.

Seeing with the nano-eye: accessing structure, function, and dynamics of matter on its natural length and time scales

NASA Astrophysics Data System (ADS)

Raschke, Markus

2015-03-01

To understand and ultimately control the properties of most functional materials, from molecular soft-matter to quantum materials, requires access to the structure, coupling, and dynamics on the elementary time and length scales that define the microscopic interactions in these materials. To gain the desired nanometer spatial resolution with simultaneous spectroscopic specificity we combine scanning probe microscopy with different optical, including coherent, nonlinear, and ultrafast spectroscopies. The underlying near-field interaction mediated by the atomic-force or scanning tunneling microscope tip provides the desired deep-sub wavelength nano-focusing enabling few-nm spatial resolution. I will introduce our generalization of the approach in terms of the near-field impedance matching to a quantum system based on special optical antenna-tip designs. The resulting enhanced and qualitatively new forms of light-matter interaction enable measurements of quantum dynamics in an interacting environment or to image the electromagnetic local density of states of thermal radiation. Other applications include the inter-molecular coupling and dynamics in soft-matter hetero-structures, surface plasmon interferometry as a probe of electronic structure and dynamics in graphene, and quantum phase transitions in correlated electron materials. These examples highlight the general applicability of the new near-field microscopy approach, complementing emergent X-ray and electron imaging tools, aiming towards the ultimate goal of probing matter on its most elementary spatio-temporal level.

Electronic structure and microscopic model of V(2)GeO(4)F(2)-a quantum spin system with S = 1.

PubMed

Rahaman, Badiur; Saha-Dasgupta, T

2007-07-25

We present first-principles density functional calculations and downfolding studies of the electronic and magnetic properties of the oxide-fluoride quantum spin system V(2)GeO(4)F(2). We discuss explicitly the nature of the exchange paths and provide quantitative estimates of magnetic exchange couplings. A microscopic modelling based on analysis of the electronic structure of this systems puts it in the interesting class of weakly coupled alternating chain S = 1 systems. Based on the microscopic model, we make inferrences about its spin excitation spectra, which needs to be tested by rigorous experimental study.

Microscopic theory of linear light scattering from mesoscopic media and in near-field optics.

PubMed

Keller, Ole

2005-08-01

On the basis of quantum mechanical response theory a microscopic propagator theory of linear light scattering from mesoscopic systems is presented. The central integral equation problem is transferred to a matrix equation problem by discretization in transitions between pairs of (many-body) energy eigenstates. The local-field calculation which appears from this approach is valid down to the microscopic region. Previous theories based on the (macroscopic) dielectric constant concept make use of spatial (geometrical) discretization and cannot in general be trusted on the mesoscopic length scale. The present theory can be applied to light scattering studies in near-field optics. After a brief discussion of the macroscopic integral equation problem a microscopic potential description of the scattering process is established. In combination with the use of microscopic electromagnetic propagators the formalism allows one to make contact to the macroscopic theory of light scattering and to the spatial photon localization problem. The quantum structure of the microscopic conductivity response tensor enables one to establish a clear physical picture of the origin of local-field phenomena in mesoscopic and near-field optics. The Huygens scalar propagator formalism is revisited and its generality in microscopic physics pointed out.

Investigation of Local Ordering in Amorphous Materials.

NASA Astrophysics Data System (ADS)

Fan, Gary Guoyou

The intent of the research described in this dissertation, as indicated by the title, is to provide a better understanding of the structure of amorphous material. The possibility of using electron microscopy to study the amorphous structure is investigated. Chapter 1 gives a brief introduction to the understanding and modeling of the amorphous structure, electron microscopy and the image analysis in general. The difficulty of using 2-D images to infer 3-D structures information is illustrated in Chapter 2, where it is shown that some high resolution images are not qualitatively different from images of white -noises weak-phase objects or those of random atomic arrangements. The means of obtaining statistical information from these images is given in Chapters 3 and 5, where the quantitative differences between experimental images and simulated white-noise or simulated images corresponding to random arrangements are revealed. The use of image processing techniques in electron microscopy and the possible artifacts are presented in Chapter 4. The pattern recognition technique outlined in Chapter 6 demonstrates a feasible mode of scanning transition electron microscope operation. Statistical analysis can be effectively performed on a large number of nano-diffraction patterns from, for example, locally ordered samples. Some recent developments in physics as well as in electron microscopy are briefly reviewed, and their possible applications in the study of amorphous structures are discussed in Chapter 7.

Mechanism of the high transition temperature for the 1111-type iron-based superconductors R FeAsO (R =rare earth ): Synergistic effects of local structures and 4 f electrons

NASA Astrophysics Data System (ADS)

Zhang, Lifang; Meng, Junling; Liu, Xiaojuan; Yao, Fen; Meng, Jian; Zhang, Hongjie

2017-07-01

Among the iron-based superconductors, the 1111-type Fe-As-based superconductors REFeAs O1 -xFx (RE = rare earth) exhibit high transition temperatures (Tc) above 40 K. We perform first-principles calculations based on density functional theory with the consideration of both electronic correlations and spin-orbit couplings on rare earths and Fe ions to study the underlying mechanism as the microscopic structural distortions in REFeAsO tuned by both lanthanide contraction and external strain. The electronic structures evolve similarly in both cases. It is found that there exist an optimal structural regime that will not only initialize but also optimize the orbital fluctuations due to the competing Fe-As and Fe-Fe crystal fields. We also find that the key structural features in REFeAsO, such as As-Fe-As bond angle, intrinsically induce the modification of the Fermi surface and dynamic spin fluctuation. These results suggest that the superconductivity is mediated by antiferromagnetic spin fluctuations. Simultaneously, we show that the rare-earth 4 f electrons play important roles on the high transition temperature whose behavior might be analogous to that of the heavy-fermion superconductors. The superconductivity of these 1111-type iron-based superconductors with high-Tc is considered to originate from the synergistic effects of local structures and 4 f electrons.

Miniature self-contained vacuum compatible electronic imaging microscope

DOEpatents

Naulleau, Patrick P.; Batson, Phillip J.; Denham, Paul E.; Jones, Michael S.

2001-01-01

A vacuum compatible CCD-based microscopic camera with an integrated illuminator. The camera can provide video or still feed from the microscope contained within a vacuum chamber. Activation of an optional integral illuminator can provide light to illuminate the microscope subject. The microscope camera comprises a housing with a objective port, modified objective, beam-splitter, CCD camera, and LED illuminator.

Ultrastructural sinusoidal changes in extrahepatic cholestasis. Light and electron microscopic immunohistochemical localization of collagen type III and type IV.

PubMed

Gulubova, M V

1996-07-01

Extrahepatic cholestasis causes excessive extracellular matrix formation perisinusoidally. Ito cells, transitional and endothelial cells are considered to be a source of extracellular matrix proteins in experimental cholestasis. The localization of collagens type III and type IV in human liver in extrahepatic cholestasis was investigated immunohistochemically in the present study. Immersion fixation was used after modification to be applied to surgical biopsies with commercially available kits. Sinusoidal changes were observed that indicated excessive collagen and matrix formation. Light microscopically, increased immunostaining with the two collagen antibodies was found perisinusoidally and portally. Ultrastructurally, collagen type III positive fibres were found beneath basement membranes of vessels, in collagen bundles and as a fibrillar network in the space of Disse. Collagen type IV immunostaining was located in portal tracts and near hepatocyte microvilli. Intracellular staining with collagen type IV was detected in the rough endoplasmic reticulum of some transitional cells. Immunostaining was located around transitional cells, Ito cells or endothelial cells mainly. Our study indicates that Ito cells, transitional and endothelial cells are the main source of collagens type III and IV in the space of Disse in extrahepatic cholestasis in humans.

Electron Source Brightness and Illumination Semi-Angle Distribution Measurement in a Transmission Electron Microscope.

PubMed

Börrnert, Felix; Renner, Julian; Kaiser, Ute

2018-05-21

The electron source brightness is an important parameter in an electron microscope. Reliable and easy brightness measurement routes are not easily found. A determination method for the illumination semi-angle distribution in transmission electron microscopy is even less well documented. Herein, we report a simple measurement route for both entities and demonstrate it on a state-of-the-art instrument. The reduced axial brightness of the FEI X-FEG with a monochromator was determined to be larger than 108 A/(m2 sr V).

An ultrafast electron microscope gun driven by two-photon photoemission from a nanotip cathode

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bormann, Reiner; Strauch, Stefanie; Schäfer, Sascha, E-mail: schaefer@ph4.physik.uni-goettingen.de

We experimentally and numerically investigate the performance of an advanced ultrafast electron source, based on two-photon photoemission from a tungsten needle cathode incorporated in an electron microscope gun geometry. Emission properties are characterized as a function of the electrostatic gun settings, and operating conditions leading to laser-triggered electron beams of very low emittance (below 20 nm mrad) are identified. The results highlight the excellent suitability of optically driven nano-cathodes for the further development of ultrafast transmission electron microscopy.

A scanning electron microscopy study of the macro-crystalline structure of 2-(2,4-dinitrobenzyl) pyridine

NASA Technical Reports Server (NTRS)

Ware, Jacqueline; Hammond, Ernest C., Jr.

1989-01-01

The compound, 2-(2,4-dinitrobenzyl) pyridine, was synthesized in the laboratory; an introductory level electron microscopy study of the macro-crystalline structure was conducted using the scanning electron microscope (SEM). The structure of these crystals was compared with the macrostructure of the crystal of 2-(2,4-dinitrobenzyl) pyridinium bromide, the hydrobromic salt of the compound which was also synthesized in the laboratory. A scanning electron microscopy crystal study was combined with a study of the principle of the electron microscope.

Ultastructural analysis on acetylcholinesterase localization in the cerebellar cortex of teleosts.

PubMed

Contestabile, A; Villani, L; Ciani, F

1977-12-28

The histochemical localization of acetylcholinesterase (AChE) was studied by electron microscopy in the cerebellar cortex of the goldfish and the catfish. The patterns of enzyme distribution show noticeable differences in the two teleost species at the level of the corresponding cerebellar structures. Among the most distinctive features is the prevailing intracellular localization of enzyme activity in the goldfish and the prevailing extracellular localization in the catfish in the molecular layer and, to a lesser extent, the granular layer. Only quantitative differences in the ability to synthesize AChE can be recorded among the different cerebellar neurons in the two species, since all these neurons exhibit different amounts of enzyme activity linked to their cytoplasmic structures. Comparing the results obtained with those of previous histochemical, experimental and developmental researches, the hypothesis seems well founded that the embryonic pool of cerebellar neurons is made up of AChE-synthesizing nruroblasts which, during development, loss or maintain to a different the mechanisms for AChE synthesis. In addition the light and electron microscope histochemistry reveals at different levels of resolution that the final pattern of AChE distribution in the cerebellar cortex is the sum of different degress of AChE synthesis by cerebellar neurons and different degrees of enzyme release in extracellular spaces.

The contributions of Otto Scherzer (1909-1982) to the development of the electron microscope.

PubMed

Marko, Michael; Rose, Harald

2010-08-01

Otto Scherzer was one of the pioneers of theoretical electron optics. He was coauthor of the first comprehensive book on electron optics and was the first to understand that round electron lenses could not be combined to correct aberrations, as is the case in light optics. He subsequently was the first to describe several alternative means to correct spherical and chromatic aberration of electron lenses. These ideas were put into practice by his laboratory and students at Darmstadt and their successors, leading to the fully corrected electron microscopes now in operation.

Tailoring Dirac Fermions in Molecular Graphene

NASA Astrophysics Data System (ADS)

Gomes, Kenjiro K.; Mar, Warren; Ko, Wonhee; Camp, Charlie D.; Rastawicki, Dominik K.; Guinea, Francisco; Manoharan, Hari C.

2012-02-01

The dynamics of electrons in solids is tied to the band structure created by a periodic atomic potential. The design of artificial lattices, assembled through atomic manipulation, opens the door to engineer electronic band structure and to create novel quantum states. We present scanning tunneling spectroscopic measurements of a nanoassembled honeycomb lattice displaying a Dirac fermion band structure. The artificial lattice is created by atomic manipulation of single CO molecules with the scanning tunneling microscope on the surface of Cu(111). The periodic potential generated by the assembled CO molecules reshapes the band structure of the two-dimensional electron gas, present as a surface state of Cu(111), into a ``molecular graphene'' system. We create local defects in the lattice to observe the quasiparticle interference patterns that unveil the underlying band structure. We present direct comparison between the tunneling data, first-principles calculations of the band structure, and tight-binding models.

Microscopy and microanalysis 1996

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bailey, G.W.; Corbett, J.M.; Dimlich, R.V.W.

1996-12-31

The Proceedings of this Annual Meeting contain paper of members from the three societies. These proceedings emphasizes the common research interests and attempts to eliminate some unwanted overlap. Topics covered are: microscopic analysis of animals with altered gene expression and in-situ gene and antibody localizations, high-resolution elemental mapping of nucleoprofein interactions, plant biology and pathology, quantitative HREM analysis of perfect and defected materials, computational methods for TEM image analysis, high-resolution FESM in materials research, frontiers in polymer microscopy and microanalysis, oxidation and corrosion, micro XRD and XRF, molecular microspectroscopy and spectral imaging, advances in confocal and multidimensional light microscopy, analyticalmore » electron microscopy in biology, correlative microscopy in biological sciences, grain-boundary microengineering, surfaces and interfaces, telepresence microscopy in education and research, MSA educational outreach, quantitative electron probe microanalysis, frontiers of analytical electron microscopy, critical issues in ceramic microstructures, dynamic organization of the cell, pathology, microbiology, high-resolution biological and cryo SEM, and scanning-probe microscopy.« less

Out-of-equilibrium catalysis of chemical reactions by electronic tunnel currents.

PubMed

Dzhioev, Alan A; Kosov, Daniel S; von Oppen, Felix

2013-04-07

We present an escape rate theory for current-induced chemical reactions. We use Keldysh nonequilibrium Green's functions to derive a Langevin equation for the reaction coordinate. Due to the out of equilibrium electronic degrees of freedom, the friction, noise, and effective temperature in the Langevin equation depend locally on the reaction coordinate. As an example, we consider the dissociation of diatomic molecules induced by the electronic current from a scanning tunnelling microscope tip. In the resonant tunnelling regime, the molecular dissociation involves two processes which are intricately interconnected: a modification of the potential energy barrier and heating of the molecule. The decrease of the molecular barrier (i.e., the current induced catalytic reduction of the barrier) accompanied by the appearance of the effective, reaction-coordinate-dependent temperature is an alternative mechanism for current-induced chemical reactions, which is distinctly different from the usual paradigm of pumping vibrational degrees of freedom.

Nanoscale deformation analysis with high-resolution transmission electron microscopy and digital image correlation

DOE PAGES

Wang, Xueju; Pan, Zhipeng; Fan, Feifei; ...

2015-09-10

We present an application of the digital image correlation (DIC) method to high-resolution transmission electron microscopy (HRTEM) images for nanoscale deformation analysis. The combination of DIC and HRTEM offers both the ultrahigh spatial resolution and high displacement detection sensitivity that are not possible with other microscope-based DIC techniques. We demonstrate the accuracy and utility of the HRTEM-DIC technique through displacement and strain analysis on amorphous silicon. Two types of error sources resulting from the transmission electron microscopy (TEM) image noise and electromagnetic-lens distortions are quantitatively investigated via rigid-body translation experiments. The local and global DIC approaches are applied for themore » analysis of diffusion- and reaction-induced deformation fields in electrochemically lithiated amorphous silicon. As a result, the DIC technique coupled with HRTEM provides a new avenue for the deformation analysis of materials at the nanometer length scales.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miao, Jianwei; Ercius, Peter; Billinge, S. J. L.

Crystallography has been fundamental to the development of many fields of science over the last century. However, much of our modern science and technology relies on materials with defects and disorders, and their three-dimensional (3D) atomic structures are not accessible to crystallography. One method capable of addressing this major challenge is atomic electron tomography. By combining advanced electron microscopes and detectors with powerful data analysis and tomographic reconstruction algorithms, it is now possible to determine the 3D atomic structure of crystal defects such as grain boundaries, stacking faults, dislocations, and point defects, as well as to precisely localize the 3Dmore » coordinates of individual atoms in materials without assuming crystallinity. In this work, we review the recent advances and the interdisciplinary science enabled by this methodology. We also outline further research needed for atomic electron tomography to address long-standing unresolved problems in the physical sciences.« less

Nature and evolution of incommensurate charge order in manganites visualized with cryogenic scanning transmission electron microscopy

PubMed Central

Savitzky, Benjamin H.; Admasu, Alemayehu S.; Kim, Jaewook; Cheong, Sang-Wook; Hovden, Robert; Kourkoutis, Lena F.

2018-01-01

Incommensurate charge order in hole-doped oxides is intertwined with exotic phenomena such as colossal magnetoresistance, high-temperature superconductivity, and electronic nematicity. Here, we map, at atomic resolution, the nature of incommensurate charge–lattice order in a manganite using scanning transmission electron microscopy at room temperature and cryogenic temperature (∼93 K). In diffraction, the ordering wave vector changes upon cooling, a behavior typically associated with incommensurate order. However, using real space measurements, we discover that the ordered state forms lattice-locked regions over a few wavelengths interspersed with phase defects and changing periodicity. The cations undergo picometer-scale (∼6 pm to 11 pm) transverse displacements, suggesting that charge–lattice coupling is strong. We further unearth phase inhomogeneity in the periodic lattice displacements at room temperature, and emergent phase coherence at 93 K. Such local phase variations govern the long-range correlations of the charge-ordered state and locally change the periodicity of the modulations, resulting in wave vector shifts in reciprocal space. These atomically resolved observations underscore the importance of lattice coupling and phase inhomogeneity, and provide a microscopic explanation for putative “incommensurate” order in hole-doped oxides. PMID:29382750

Electron beam induced deposition of silicon nanostructures from a liquid phase precursor.

PubMed

Liu, Yin; Chen, Xin; Noh, Kyong Wook; Dillon, Shen J

2012-09-28

This work demonstrates electron beam induced deposition of silicon from a SiCl(4) liquid precursor in a transmission electron microscope and a scanning electron microscope. Silicon nanodots of tunable size are reproducibly grown in controlled geometries. The volume of these features increases linearly with deposition time. The results indicate that secondary electrons generated at the substrate surface serve as the primary source of silicon reduction. However, at high current densities the influence of the primary electrons is observed to retard growth. The results demonstrate a new approach to fabricating silicon nanostructures and provide fundamental insights into the mechanism for liquid phase electron beam induced deposition.

Electron beam induced deposition of silicon nanostructures from a liquid phase precursor

NASA Astrophysics Data System (ADS)

Liu, Yin; Chen, Xin; Noh, Kyong Wook; Dillon, Shen J.

2012-09-01

This work demonstrates electron beam induced deposition of silicon from a SiCl4 liquid precursor in a transmission electron microscope and a scanning electron microscope. Silicon nanodots of tunable size are reproducibly grown in controlled geometries. The volume of these features increases linearly with deposition time. The results indicate that secondary electrons generated at the substrate surface serve as the primary source of silicon reduction. However, at high current densities the influence of the primary electrons is observed to retard growth. The results demonstrate a new approach to fabricating silicon nanostructures and provide fundamental insights into the mechanism for liquid phase electron beam induced deposition.

Transmission Electron Microscope Measures Lattice Parameters

NASA Technical Reports Server (NTRS)

Pike, William T.

1996-01-01

Convergent-beam microdiffraction (CBM) in thermionic-emission transmission electron microscope (TEM) is technique for measuring lattice parameters of nanometer-sized specimens of crystalline materials. Lattice parameters determined by use of CBM accurate to within few parts in thousand. Technique developed especially for use in quantifying lattice parameters, and thus strains, in epitaxial mismatched-crystal-lattice multilayer structures in multiple-quantum-well and other advanced semiconductor electronic devices. Ability to determine strains in indivdual layers contributes to understanding of novel electronic behaviors of devices.

Ponderomotive phase plate for transmission electron microscopes

DOEpatents

Reed, Bryan W [Livermore, CA

2012-07-10

A ponderomotive phase plate system and method for controllably producing highly tunable phase contrast transfer functions in a transmission electron microscope (TEM) for high resolution and biological phase contrast imaging. The system and method includes a laser source and a beam transport system to produce a focused laser crossover as a phase plate, so that a ponderomotive potential of the focused laser crossover produces a scattering-angle-dependent phase shift in the electrons of the post-sample electron beam corresponding to a desired phase contrast transfer function.

In situ flat embedding of monolayers and cell relocation in the acrylic resin LR white for comparative light and electron microscopy studies.

PubMed

Steiner, M; Schöfer, C; Mosgoeller, W

1994-12-01

A simple and reliable method has been developed for the in situ LR White embedding of cell monolayers grown on glass cover-slips. Combined with cytochemical or immunological procedures, this technique allows light and/or electron microscopy investigations of a large number of cells in the same horizontal plane within a relatively short period of time. It can be applied to cells grown on microgrid finder cover-slips which allows a distinct site of even an individual cell of a monolayer to be studied at first at the light microscope level and subsequently at the electron microscope level. Hence, it is also suitable for controlling manipulation of single cells, followed by their serial sectioning after relocation in the electron microscope.

Effects of electrohydraulic extracorporeal shock wave lithotripsy on submandibular gland in the rat: electron microscopic evaluation.

PubMed

Bayar, Nuray; Kaymaz, F Figen; Apan, Alpaslan; Yilmaz, Erdal; Cakar, A Nur

2002-05-15

Extracorporeal shockwave lithotripsy (ESWL) has been applied in sialolithiasis as a new treatment modality. The aim of this experimental study is to investigate the local effects of electrohydraulic ESWL applied to the right submandibular gland of the rats. This prospective study was conveyed in four groups; groups I, II, III and IV; each group consisting of 20, 20, 18 and 9 rats, respectively, with a randomized distribution. Groups I, II, III and IV received 250, 500, 1000 and 2000 shock waves at 14-16 kV (average 15.1 kV), respectively, to the right submandibular glands on the 0th day. In groups I, II, III, right submandibular glands of the rats were removed on the 0th, 1st, 7th and 15th days; in group IV, this procedure could be managed only on the 0th and 7th days. Light and electron microscopic evaluation were assessed. Using the light microscopic changes, severity of damage score of the glands (SDS) was found. Statistical analysis was done using SDSs. Light and electron microscopic observations have shown that the damage produced by the shock waves were confined to focal areas in the acinar cells (AC), granulated convoluted tubule (GCT) cells and blood vessels at all doses applied. Vacuolization in the cytoplasms of the AC and GCT cells, disintegration of membranes, alteration in the cytoplasmic organization, swelling of the mitochondria and loss of the features were observed on electron microscopy. Increase in the secretion rate; stasis and dilatation in the blood vessels; blebbing and loss of features in the cytoplasm of the endothelial cells were observed. According to the result of the statistical analysis using SDSs; at 250 shock wave dose, a statistically significant difference between the SDSs of the days (0th, 1st, 7th and 15th) was found (P<0.05). The SDS on the 0th day was found to have the lowest value among the other days. And also a statistically significant difference was found on the 0th day between the SDSs at doses of 250, 500, 1000 and 2000 shock waves (P<0.05). The SDS at 250 and 500 shock waves was found to have the lower value than the SDS at the 2000 shock wave. It was observed that produced damage was less prominent by small doses (250, 500 doses) initially (0th day). Electrohydraulic ESWL caused a "patchy type" generalized pathology on submandibular glands of the rats and damaged focal areas were widespread all through the gland from the 1st day on. Formation of the damage was concluded to be related to the direct effect of the shock waves rather than the dose used. Electrohydraulic lithotripters are not suitable for sialolithiasis because of the focus problems, local tissue damage and the risk of the damage to the adjacent structures.

Mars Life? - Microscopic Tubular Structures

NASA Image and Video Library

1996-08-09

This electron microscope image shows extremely tiny tubular structures that are possible microscopic fossils of bacteria-like organisms that may have lived on Mars more than 3.6 billion years ago. http://photojournal.jpl.nasa.gov/catalog/PIA00285

Mars Life? - Microscopic Egg-shaped Structures

NASA Image and Video Library

1996-08-09

This electron microscope image shows egg-shaped structures, some of which may be possible microscopic fossils of Martian origin as discussed by NASA research published in the Aug. 16, 1996. http://photojournal.jpl.nasa.gov/catalog/PIA00286

CHARACTERISTICS OF INDIVIDUAL PARTICLES AT A RURAL SITE IN THE EASTERN UNITED STATES

EPA Science Inventory

To determine the nature of aerosol particles in a rural area of the eastern United States, aerosol samples were collected at Deep Creek Lake, Maryland, on various substrates and analyzed by a scanning electron microscope (SEM) and a transmission electron microscope (TEM). SEM ana...

77 FR 33422 - The Regents of the University of California, et al.; Notice of Consolidated Decision on...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-06-06

... DEPARTMENT OF COMMERCE International Trade Administration The Regents of the University of...: Washington University in St. Louis, Saint Louis, MO 63130. Instrument: Electron Microscope. Manufacturer: FEI.... Applicant: The Regents of the University of California, Berkeley, CA 94720. Instrument: Electron Microscope...

Neuroanatomy from Mesoscopic to Nanoscopic Scales: An Improved Method for the Observation of Semithin Sections by High-Resolution Scanning Electron Microscopy

PubMed Central

Rodríguez, José-Rodrigo; Turégano-López, Marta; DeFelipe, Javier; Merchán-Pérez, Angel

2018-01-01

Semithin sections are commonly used to examine large areas of tissue with an optical microscope, in order to locate and trim the regions that will later be studied with the electron microscope. Ideally, the observation of semithin sections would be from mesoscopic to nanoscopic scales directly, instead of using light microscopy and then electron microscopy (EM). Here we propose a method that makes it possible to obtain high-resolution scanning EM images of large areas of the brain in the millimeter to nanometer range. Since our method is compatible with light microscopy, it is also feasible to generate hybrid light and electron microscopic maps. Additionally, the same tissue blocks that have been used to obtain semithin sections can later be used, if necessary, for transmission EM, or for focused ion beam milling and scanning electron microscopy (FIB-SEM). PMID:29568263

Neuroanatomy from Mesoscopic to Nanoscopic Scales: An Improved Method for the Observation of Semithin Sections by High-Resolution Scanning Electron Microscopy.

PubMed

Rodríguez, José-Rodrigo; Turégano-López, Marta; DeFelipe, Javier; Merchán-Pérez, Angel

2018-01-01

Semithin sections are commonly used to examine large areas of tissue with an optical microscope, in order to locate and trim the regions that will later be studied with the electron microscope. Ideally, the observation of semithin sections would be from mesoscopic to nanoscopic scales directly, instead of using light microscopy and then electron microscopy (EM). Here we propose a method that makes it possible to obtain high-resolution scanning EM images of large areas of the brain in the millimeter to nanometer range. Since our method is compatible with light microscopy, it is also feasible to generate hybrid light and electron microscopic maps. Additionally, the same tissue blocks that have been used to obtain semithin sections can later be used, if necessary, for transmission EM, or for focused ion beam milling and scanning electron microscopy (FIB-SEM).

Variations in contrast of scanning electron microscope images for microstructure analysis of Si-based semiconductor materials.

PubMed

Itakura, Masaru; Kuwano, Noriyuki; Sato, Kaoru; Tachibana, Shigeaki

2010-08-01

Image contrasts of Si-based semiconducting materials have been investigated by using the latest scanning electron microscope with various detectors under a range of experimental conditions. Under a very low accelerating voltage (500 V), we obtained a good image contrast between crystalline SiGe whiskers and the amorphous matrix using an in-lens secondary electron (SE) detector, while the conventional topographic SE image and the compositional backscattered electron (BSE) image gave no distinct contrast. By using an angular-selective BSE (AsB) detector for wide-angle scattered BSE, on the other hand, the crystal grains in amorphous matrix can be clearly visualized as 'channelling contrast'. The image contrast is very similar to that of their transmission electron microscope image. The in-lens SE (true SE falling dots SE1) and the AsB (channelling) contrasts are quite useful to distinguish crystalline parts from amorphous ones.

Dynamic imaging with electron microscopy

ScienceCinema

Campbell, Geoffrey; McKeown, Joe; Santala, Melissa

2018-02-13

Livermore researchers have perfected an electron microscope to study fast-evolving material processes and chemical reactions. By applying engineering, microscopy, and laser expertise to the decades-old technology of electron microscopy, the dynamic transmission electron microscope (DTEM) team has developed a technique that can capture images of phenomena that are both very small and very fast. DTEM uses a precisely timed laser pulse to achieve a short but intense electron beam for imaging. When synchronized with a dynamic event in the microscope's field of view, DTEM allows scientists to record and measure material changes in action. A new movie-mode capability, which earned a 2013 R&D 100 Award from R&D Magazine, uses up to nine laser pulses to sequentially capture fast, irreversible, even one-of-a-kind material changes at the nanometer scale. DTEM projects are advancing basic and applied materials research, including such areas as nanostructure growth, phase transformations, and chemical reactions.

Remote activation and detection of up-converted luminescence via surface plasmon polaritons propagating in a silver nanowire.

PubMed

Prymaczek, A; Cwierzona, M; Grzelak, J; Kowalska, D; Nyk, M; Mackowski, S; Piatkowski, D

2018-06-27

In this paper, we demonstrate remote activation and detection of the 2-photon up-conversion luminescence via surface plasmon polaritons propagating in a long silver nanowire. The hybrid nanostructure was assembled by locally depositing a submicron droplet of nanocrystal-containing colloidal solution on one of the ends of the metallic nanowire. When - using a classic confocal microscope - the second end of the nanowire, without the nanocrystals, is illuminated with infrared laser light, we observe strong emission from the same end. Therefore, it indicates that surface plasmon polaritons activated with infrared light at the second end of the nanowire propagate along it and can excite nanocrystals in the droplet at the opposite end. Subsequently, the excited nanocrystals up-convert the energy and by launching surface plasmon polaritons can guide the up-converted luminescence back to the starting point. The emergence of this effect is much more pronounced for a laser polarized along the nanowire. The spectral and temporal character of this emission reveals strong interactions between surface plasmon polaritons and electronic states of the nanocrystals. The details of local and non-local aspects of the effects of remote excitation and guiding of energy in a silver nanowire are elucidated using a unique experimental setup, based on two microscope objectives for spatial separation and control of both excitation and emission beams.

Super-resolution photoacoustic microscopy using a localized near-field of a plasmonic nanoaperture: a three-dimensional simulation study

NASA Astrophysics Data System (ADS)

Park, Byullee; Lee, Hongki; Upputuri, Paul Kumar; Pramanik, Manojit; Kim, Donghyun; Kim, Chulhong

2018-02-01

Super-resolution microscopy has been increasingly important to delineate nanoscale biological structures or nanoparticles. With these increasing demands, several imaging modalities, including super-resolution fluorescence microscope (SRFM) and electron microscope (EM), have been developed and commercialized. These modalities achieve nanoscale resolution, however, SRFM cannot image without fluorescence, and sample preparation of EM is not suitable for biological specimens. To overcome those disadvantages, we have numerically studied the possibility of superresolution photoacoustic microscopy (SR-PAM) based on near-field localization of light. Photoacoustic (PA) signal is generally acquired based on optical absorption contrast; thus it requires no agents or pre-processing for the samples. The lateral resolution of the conventional photoacoustic microscopy is limited to 200 nm by diffraction limit, therefore reducing the lateral resolution is a major research impetus. Our approach to breaking resolution limit is to use laser pulses of extremely small spot size as a light source. In this research, we simulated the PA signal by constructing the three dimensional SR-PAM system environment using the k-Wave toolbox. As the light source, we simulated ultrashort light pulses using geometrical nanoaperture with near-field localization of surface plasmons. Through the PA simulation, we have successfully distinguish cuboids spaced 3 nm apart. In the near future, we will develop the SR-PAM and it will contribute to biomedical and material sciences.

Energy-filtered real- and k-space secondary and energy-loss electron imaging with Dual Emission Electron spectro-Microscope: Cs/Mo(110).

PubMed

Grzelakowski, Krzysztof P

2016-05-01

Since its introduction the importance of complementary k||-space (LEED) and real space (LEEM) information in the investigation of surface science phenomena has been widely demonstrated over the last five decades. In this paper we report the application of a novel kind of electron spectromicroscope Dual Emission Electron spectroMicroscope (DEEM) with two independent electron optical channels for reciprocal and real space quasi-simultaneous imaging in investigation of a Cs covered Mo(110) single crystal by using the 800eV electron beam from an "in-lens" electron gun system developed for the sample illumination. With the DEEM spectromicroscope it is possible to observe dynamic, irreversible processes at surfaces in the energy-filtered real space and in the corresponding energy-filtered kǁ-space quasi-simultaneously in two independent imaging columns. The novel concept of the high energy electron beam sample illumination in the cathode lens based microscopes allows chemically selective imaging and analysis under laboratory conditions. Copyright © 2015 Elsevier B.V. All rights reserved.

Immunolocalization of thymosin alpha 1, thymopoietin and thymulin in mouse thymic epithelial cells at different stages of culture: a light and electron microscopic study.

PubMed Central

Fabien, N; Auger, C; Monier, J C

1988-01-01

The secretory evolution of the thymic hormones (thymulin, thymosin alpha 1 and thymopoietin) in cultured thymic reticuloepithelial cells (TREC) was studied by immunocytochemical techniques using monoclonal anti-thymulin or anti-thymosin alpha 1 and polyclonal anti-thymopoietin antibodies (Ab). The culture of TREC was performed with a medium where L-valine was replaced by D-valine, thus ensuring rapid and selective development of these cells. The number of thymulin, thymosin alpha 1 or thymopoietin-containing cells increased progressively from Day 6 to Day 12 of the culture. The localization of the three thymic hormones within the TREC also varied according to the age of the culture. By light microscopy the staining of the three hormones was localized in some cytoplasmic granules at the beginning of the culture and at Day 90, while at Day 12 it was throughout the cytoplasm. In electron microscopy these localizations corresponded respectively to vacuoles of different sizes and to cytosol. All these results show that the synthesis and excretion of thymulin, thymosin alpha 1 and thymopoietin evolve during the development of TREC in culture. Images Figure 1 Figure 2 PMID:3284819

Studies by immune electron microscopy of hepatitis B surface antigen in PLC/PRF/5 cells.

PubMed

Shibayama, T; Watanabe, T; Kojima, H; Yoshikawa, A; Watanabe, S; Kamimura, T; Suzuki, S; Ichida, F

1984-01-01

Electron microscopic studies of the morphology of hepatitis B surface antigen (HBsAg) produced by PLC/PRF/5 cells in vitro were carried out. Aggregates of 20-nm spherical particles in 3-day culture supernatants were observed by immune electron microscopy (IEM). Aggregates of tubular structures were found with IEM in the extracts of the cells. Tubular structures 18 to 22 nm in diameter were seen by electron microscopy (EM) in the cisternae of the endoplasmic reticulum in 2-3% of the cells. The tubular structures in the cytoplasm and extracts of PLC/PRF/5 cells resembled those observed in the hepatocytes of human carriers of hepatitis B virus (HBV). Intracellular localization of HBsAg in PLC/PRF/5 cells by direct peroxidase-conjugated antibody staining was observed on the tubular structures and the cisternal wall, which contained these structures. Rotation technique analysis indicated that the tubular structures were composed of 11 or 12 subunits.

Low cost, high performance processing of single particle cryo-electron microscopy data in the cloud.

PubMed

Cianfrocco, Michael A; Leschziner, Andres E

2015-05-08

The advent of a new generation of electron microscopes and direct electron detectors has realized the potential of single particle cryo-electron microscopy (cryo-EM) as a technique to generate high-resolution structures. Calculating these structures requires high performance computing clusters, a resource that may be limiting to many likely cryo-EM users. To address this limitation and facilitate the spread of cryo-EM, we developed a publicly available 'off-the-shelf' computing environment on Amazon's elastic cloud computing infrastructure. This environment provides users with single particle cryo-EM software packages and the ability to create computing clusters with 16-480+ CPUs. We tested our computing environment using a publicly available 80S yeast ribosome dataset and estimate that laboratories could determine high-resolution cryo-EM structures for $50 to $1500 per structure within a timeframe comparable to local clusters. Our analysis shows that Amazon's cloud computing environment may offer a viable computing environment for cryo-EM.

Detecting element specific electrons from a single cobalt nanocluster with synchrotron x-ray scanning tunneling microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kersell, Heath; Shirato, Nozomi; Cummings, Marvin

We use a nanofabricated scanning tunneling microscope tip as a detector to investigate local X-ray induced tunneling and electron emission from a single cobalt nanocluster on a Au(111) surface. The tip-detector is positioned a few angstroms above the nanocluster, and ramping the incident X-ray energy across the Co photoabsorption K-edge enables the detection of element specific electrons. Atomic-scale spatial dependent changes in the X-ray absorption cross section are directly measured by taking the X-ray induced current as a function of X-ray energy. From the measured sample and tip currents, element specific X-ray induced current components can be separated and therebymore » the corresponding yields for the X-ray induced processes of the single cobalt nanocluster can be determined. The detection of element specific synchrotron X-ray induced electrons of a single nanocluster opens a new avenue for materials characterization on a one particle at-a-time basis.« less

Detecting element specific electrons from a single cobalt nanocluster with synchrotron x-ray scanning tunneling microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kersell, Heath; Shirato, Nozomi; Cummings, Marvin

Here, we use a nanofabricated scanning tunneling microscope tip as a detector to investigate local X-ray induced tunneling and electron emission from a single cobalt nanocluster on a Au(111) surface. The tip-detector is positioned a few angstroms above the nanocluster, and ramping the incident X-ray energy across the Co photoabsorption K-edge enables the detection of element specific electrons. Atomic-scale spatial dependent changes in the X-ray absorption cross section are directly measured by taking the X-ray induced current as a function of X-ray energy. From the measured sample and tip currents, element specific X-ray induced current components can be separated andmore » thereby the corresponding yields for the X-ray induced processes of the single cobalt nanocluster can be determined. The detection of element specific synchrotron X-ray induced electrons of a single nanocluster opens a new avenue for materials characterization on a one particle at-a-time basis.« less

Analytical modeling of electron energy loss spectroscopy of graphene: Ab initio study versus extended hydrodynamic model.

PubMed

Djordjević, Tijana; Radović, Ivan; Despoja, Vito; Lyon, Keenan; Borka, Duško; Mišković, Zoran L

2018-01-01

We present an analytical modeling of the electron energy loss (EEL) spectroscopy data for free-standing graphene obtained by scanning transmission electron microscope. The probability density for energy loss of fast electrons traversing graphene under normal incidence is evaluated using an optical approximation based on the conductivity of graphene given in the local, i.e., frequency-dependent form derived by both a two-dimensional, two-fluid extended hydrodynamic (eHD) model and an ab initio method. We compare the results for the real and imaginary parts of the optical conductivity in graphene obtained by these two methods. The calculated probability density is directly compared with the EEL spectra from three independent experiments and we find very good agreement, especially in the case of the eHD model. Furthermore, we point out that the subtraction of the zero-loss peak from the experimental EEL spectra has a strong influence on the analytical model for the EEL spectroscopy data. Copyright © 2017 Elsevier B.V. All rights reserved.

Detecting element specific electrons from a single cobalt nanocluster with synchrotron x-ray scanning tunneling microscopy

DOE PAGES

Kersell, Heath; Shirato, Nozomi; Cummings, Marvin; ...

2017-09-05

Here, we use a nanofabricated scanning tunneling microscope tip as a detector to investigate local X-ray induced tunneling and electron emission from a single cobalt nanocluster on a Au(111) surface. The tip-detector is positioned a few angstroms above the nanocluster, and ramping the incident X-ray energy across the Co photoabsorption K-edge enables the detection of element specific electrons. Atomic-scale spatial dependent changes in the X-ray absorption cross section are directly measured by taking the X-ray induced current as a function of X-ray energy. From the measured sample and tip currents, element specific X-ray induced current components can be separated andmore » thereby the corresponding yields for the X-ray induced processes of the single cobalt nanocluster can be determined. The detection of element specific synchrotron X-ray induced electrons of a single nanocluster opens a new avenue for materials characterization on a one particle at-a-time basis.« less

Development of a secondary electron energy analyzer for a transmission electron microscope.

PubMed

Magara, Hideyuki; Tomita, Takeshi; Kondo, Yukihito; Sato, Takafumi; Akase, Zentaro; Shindo, Daisuke

2018-04-01

A secondary electron (SE) energy analyzer was developed for a transmission electron microscope. The analyzer comprises a microchannel plate (MCP) for detecting electrons, a coil for collecting SEs emitted from the specimen, a tube for reducing the number of backscattered electrons incident on the MCP, and a retarding mesh for selecting the energy of SEs incident on the MCP. The detection of the SEs associated with charging phenomena around a charged specimen was attempted by performing electron holography and SE spectroscopy using the energy analyzer. The results suggest that it is possible to obtain the energy spectra of SEs using the analyzer and the charging states of a specimen by electron holography simultaneously.

An investigation of nitride precipitates in archaeological iron artefacts from Poland.

PubMed

Kedzierski, Z; Stepiński, J; Zielińska-Lipiec, A

2010-03-01

The paper describes the investigations of nitride precipitates in a spearhead and a sword found in the territory of Poland, in cremation graveyards of the Przeworsk Culture, dated to the Roman Period. Three different techniques of the examination of nitride precipitates were employed: optical microscope, scanning electron microscope (scanning electron microscope with energy dispersive X-ray spectrometer) and transmission electron microscope. Two types of precipitates have been observed, and their plate-like shape was demonstrated. The large precipitate has been confirmed to be gamma'-Fe(4)N, whereas the small one has been identified as alpha''-Fe(16)N(2). The origin of nitride precipitates in archaeological iron artefacts from Poland is probably a result of the manufacturing process or cremation as part of burial rites. An examination of available iron artefacts indicates that nitride precipitates (have only limited effect on mechanical properties) influence the hardness of metal only to a very limited degree.

Local Anodic Oxidation of Thin GeO Films and Formation of Nanostructures Based on Them

NASA Astrophysics Data System (ADS)

Astankova, K. N.; Kozhukhov, A. S.; Azarov, I. A.; Gorokhov, E. B.; Sheglov, D. V.; Latyshev, A. V.

2018-04-01

The process of local anodic oxidation of thin GeO films has been studied using an atomic force microscope. The electron-probe microanalysis showed that oxidized areas of a GeO film were germanium dioxide. The effect of the voltage pulse duration applied to the probe-substrate system and the atmospheric humidity on the height of the oxide structures has been studied. The kinetics of the local anodic oxidation (LAO) in a semi-contact mode obeys the Cabrera-Mott model for large times. The initial growth rate of the oxide ( R 0) significantly increases and the time of starting the oxidation ( t 0) decreases as the atmospheric humidity increases by 20%, which is related to an increase in the concentration of oxygen-containing ions at the surface of the oxidized GeO film. It was shown that nanostructures in thin GeO layers can be formed by the LAO method.

Nanoscale assembly of superconducting vortices with scanning tunnelling microscope tip

PubMed Central

Ge, Jun-Yi; Gladilin, Vladimir N.; Tempere, Jacques; Xue, Cun; Devreese, Jozef T.; Van de Vondel, Joris; Zhou, Youhe; Moshchalkov, Victor V.

2016-01-01

Vortices play a crucial role in determining the properties of superconductors as well as their applications. Therefore, characterization and manipulation of vortices, especially at the single-vortex level, is of great importance. Among many techniques to study single vortices, scanning tunnelling microscopy (STM) stands out as a powerful tool, due to its ability to detect the local electronic states and high spatial resolution. However, local control of superconductivity as well as the manipulation of individual vortices with the STM tip is still lacking. Here we report a new function of the STM, namely to control the local pinning in a superconductor through the heating effect. Such effect allows us to quench the superconducting state at nanoscale, and leads to the growth of vortex clusters whose size can be controlled by the bias voltage. We also demonstrate the use of an STM tip to assemble single-quantum vortices into desired nanoscale configurations. PMID:27934960

Ultra-structural hair alterations in Friedreich's ataxia: A scanning electron microscopic investigation.

PubMed

Turkmenoglu, F Pinar; Kasirga, U Baran; Celik, H Hamdi

2015-08-01

Friedreich's ataxia (FRDA) is an autosomal recessive inherited disorder involving progressive damage to the central and peripheral nervous systems and cardiomyopathy. FRDA is caused by the silencing of the FXN gene and reduced levels of the encoded protein, frataxin. Frataxin is a mitochondrial protein that functions primarily in iron-sulfur cluster synthesis. Skin disorders including hair abnormalities have previously been reported in patients with mitochondrial disorders. However, to our knowledge, ultra-structural hair alterations in FRDA were not demonstrated. The purpose of this study was to determine ultra-structural alterations in the hairs of FRDA patients as well as carriers. Hair specimen from four patients, who are in different stages of the disease, and two carriers were examined by scanning electron microscope. Thin and weak hair follicles with absence of homogeneities on the cuticular surface, local damages of the cuticular layer, cuticular fractures were detected in both carriers and patients, but these alterations were much more prominent in the hair follicles of patients. In addition, erosions on the surface of the cuticle and local deep cavities just under the cuticular level were observed only in patients. Indistinct cuticular pattern, pores on the cuticular surface, and presence of concavities on the hair follicle were also detected in patients in later stages of the disease. According to our results, progression of the disease increased the alterations on hair structure. We suggest that ultra-structural alterations observed in hair samples might be due to oxidative stress caused by deficient frataxin expression in mitochondria. © 2015 Wiley Periodicals, Inc.

Aberration corrected 1.2-MV cold field-emission transmission electron microscope with a sub-50-pm resolution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Akashi, Tetsuya; Takahashi, Yoshio; Tanigaki, Toshiaki, E-mail: toshiaki.tanigaki.mv@hitachi.com

2015-02-16

Atomic-resolution electromagnetic field observation is critical to the development of advanced materials and to the unveiling of their fundamental physics. For this purpose, a spherical-aberration corrected 1.2-MV cold field-emission transmission electron microscope has been developed. The microscope has the following superior properties: stabilized accelerating voltage, minimized electrical and mechanical fluctuation, and coherent electron emission. These properties have enabled to obtain 43-pm information transfer. On the bases of these performances, a 43-pm resolution has been obtained by correcting lens aberrations up to the third order. Observations of GaN [411] thin crystal showed a projected atomic locations with a separation of 44 pm.

Indentation-Enabled In Situ Mechanical Characterization of Micro/Nanopillars in Electron Microscopes

NASA Astrophysics Data System (ADS)

Guo, Qiang; Fu, Xidan; Guo, Xiaolei; Liu, Zhiying; Shi, Yan; Zhang, Di

2018-04-01

Indentation-enabled micro/nanomechanical characterization of small-scale specimens provides powerful new tools for probing materials properties that were once unattainable by conventional experimental methods. Recent advancement in instrumentation further allows mechanical testing to be carried out in situ in electron microscopes, with high spatial and temporal resolution. This review discusses the recent development of nanoindentation-enabled in situ mechanical testing in electron microscopes, with an emphasis on the study of micro/nanopillars. Focus is given to novel applications beyond simple compressive and tensile testing that have been developed in the past few years, and limitations and possible future research directions in this field are proposed and discussed.

Spin microscope based on optically detected magnetic resonance

DOEpatents

Berman, Gennady P [Los Alamos, NM; Chernobrod, Boris M [Los Alamos, NM

2010-06-29

The invention relates to scanning magnetic microscope which has a photoluminescent nanoprobe implanted in the tip apex of an atomic force microscope (AFM), a scanning tunneling microscope (STM) or a near-field scanning optical microscope (NSOM) and exhibits optically detected magnetic resonance (ODMR) in the vicinity of unpaired electron spins or nuclear magnetic moments in the sample material. The described spin microscope has demonstrated nanoscale lateral resolution and single spin sensitivity for the AFM and STM embodiments.

Spin microscope based on optically detected magnetic resonance

DOEpatents

Berman, Gennady P.; Chernobrod, Boris M.

2009-11-10

The invention relates to scanning magnetic microscope which has a photoluminescent nanoprobe implanted in the tip apex of an atomic force microscope (AFM), a scanning tunneling microscope (STM) or a near-field scanning optical microscope (NSOM) and exhibits optically detected magnetic resonance (ODMR) in the vicinity of impaired electron spins or nuclear magnetic moments in the sample material. The described spin microscope has demonstrated nanoscale lateral resolution and single spin sensitivity for the AFM and STM embodiments.

Spin microscope based on optically detected magnetic resonance

DOEpatents

Berman, Gennady P.; Chernobrod, Boris M.

2007-12-11

The invention relates to scanning magnetic microscope which has a photoluminescent nanoprobe implanted in the tip apex of an atomic force microscope (AFM), a scanning tunneling microscope (STM) or a near-field scanning optical microscope (NSOM) and exhibits optically detected magnetic resonance (ODMR) in the vicinity of unpaired electron spins or nuclear magnetic moments in the sample material. The described spin microscope has demonstrated nanoscale lateral resolution and single spin sensitivity for the AFM and STM embodiments.

Spin microscope based on optically detected magnetic resonance

DOEpatents

Berman, Gennady P [Los Alamos, NM; Chernobrod, Boris M [Los Alamos, NM

2010-07-13

The invention relates to scanning magnetic microscope which has a photoluminescent nanoprobe implanted in the tip apex of an atomic force microscope (AFM), a scanning tunneling microscope (STM) or a near-field scanning optical microscope (NSOM) and exhibits optically detected magnetic resonance (ODMR) in the vicinity of unpaired electron spins or nuclear magnetic moments in the sample material. The described spin microscope has demonstrated nanoscale lateral resolution and single spin sensitivity for the AFM and STM embodiments.

Spin microscope based on optically detected magnetic resonance

DOEpatents

Berman, Gennady P [Los Alamos, NM; Chernobrod, Boris M [Los Alamos, NM

2009-10-27

The invention relates to scanning magnetic microscope which has a photoluminescent nanoprobe implanted in the tip apex of an atomic force microscope (AFM), a scanning tunneling microscope (STM) or a near-field scanning optical microscope (NSOM) and exhibits optically detected magnetic resonance (ODMR) in the vicinity of unpaired electron spins or nuclear magnetic moments in the sample material. The described spin microscope has demonstrated nanoscale lateral resolution and single spin sensitivity for the AFM and STM embodiments.

Atomic force microscopic imaging of Acanthamoeba castellanii and Balamuthia mandrillaris trophozoites and cysts.

PubMed

Aqeel, Yousuf; Siddiqui, Ruqaiyyah; Ateeq, Muhammad; Raza Shah, Muhammad; Kulsoom, Huma; Khan, Naveed Ahmed

2015-01-01

Light microscopy and electron microscopy have been successfully used in the study of microbes, as well as free-living protists. Unlike light microscopy, which enables us to observe living organisms or the electron microscope which provides a two-dimensional image, atomic force microscopy provides a three-dimensional surface profile. Here, we observed two free-living amoebae, Acanthamoeba castellanii and Balamuthia mandrillaris under the phase contrast inverted microscope, transmission electron microscope and atomic force microscope. Although light microscopy was of lower magnification, it revealed functional biology of live amoebae such as motility and osmoregulation using contractile vacuoles of the trophozoite stage, but it is of limited value in defining the cyst stage. In contrast, transmission electron microscopy showed significantly greater magnification and resolution to reveal the ultra-structural features of trophozoites and cysts including intracellular organelles and cyst wall characteristics but it only produced a snapshot in time of a dead amoeba cell. Atomic force microscopy produced three-dimensional images providing detailed topographic description of shape and surface, phase imaging measuring boundary stiffness, and amplitude measurements including width, height and length of A. castellanii and B. mandrillaris trophozoites and cysts. These results demonstrate the importance of the application of various microscopic methods in the biological and structural characterization of the whole cell, ultra-structural features, as well as surface components and cytoskeleton of protist pathogens. © 2014 The Author(s) Journal of Eukaryotic Microbiology © 2014 International Society of Protistologists.

Fluctuating exciton localization in giant π-conjugated spoked-wheel macrocycles.

PubMed

Aggarwal, A Vikas; Thiessen, Alexander; Idelson, Alissa; Kalle, Daniel; Würsch, Dominik; Stangl, Thomas; Steiner, Florian; Jester, Stefan-S; Vogelsang, Jan; Höger, Sigurd; Lupton, John M

2013-11-01

Conjugated polymers offer potential for many diverse applications, but we still lack a fundamental microscopic understanding of their electronic structure. Elementary photoexcitations (excitons) span only a few nanometres of a molecule, which itself can extend over microns, and how their behaviour is affected by molecular dimensions is not immediately obvious. For example, where is the exciton formed within a conjugated segment and is it always situated on the same repeat units? Here, we introduce structurally rigid molecular spoked wheels, 6 nm in diameter, as a model of extended π conjugation. Single-molecule fluorescence reveals random exciton localization, which leads to temporally varying emission polarization. Initially, this random localization arises after every photon absorption event because of temperature-independent spontaneous symmetry breaking. These fast fluctuations are slowed to millisecond timescales after prolonged illumination. Intramolecular heterogeneity is revealed in cryogenic spectroscopy by jumps in transition energy, but emission polarization can also switch without a spectral jump occurring, which implies long-range homogeneity in the local dielectric environment.

Fluctuating exciton localization in giant π-conjugated spoked-wheel macrocycles

NASA Astrophysics Data System (ADS)

Aggarwal, A. Vikas; Thiessen, Alexander; Idelson, Alissa; Kalle, Daniel; Würsch, Dominik; Stangl, Thomas; Steiner, Florian; Jester, Stefan-S.; Vogelsang, Jan; Höger, Sigurd; Lupton, John M.

2013-11-01

Conjugated polymers offer potential for many diverse applications, but we still lack a fundamental microscopic understanding of their electronic structure. Elementary photoexcitations (excitons) span only a few nanometres of a molecule, which itself can extend over microns, and how their behaviour is affected by molecular dimensions is not immediately obvious. For example, where is the exciton formed within a conjugated segment and is it always situated on the same repeat units? Here, we introduce structurally rigid molecular spoked wheels, 6 nm in diameter, as a model of extended π conjugation. Single-molecule fluorescence reveals random exciton localization, which leads to temporally varying emission polarization. Initially, this random localization arises after every photon absorption event because of temperature-independent spontaneous symmetry breaking. These fast fluctuations are slowed to millisecond timescales after prolonged illumination. Intramolecular heterogeneity is revealed in cryogenic spectroscopy by jumps in transition energy, but emission polarization can also switch without a spectral jump occurring, which implies long-range homogeneity in the local dielectric environment.

The hybrid lattice of KxFe2−ySe2: where superconductivity and magnetism coexist

PubMed Central

Louca, Despina; Park, Keeseong; Li, Bing; Neuefeind, Joerg; Yan, Jiaqiang

2013-01-01

Much remains unknown of the microscopic origin of superconductivity in atomically disordered systems of amorphous alloys or in crystals riddled with defects. A manifestation of this conundrum is envisaged in the highly defective superconductor of KxFe2−ySe2. How can superconductivity survive under such crude conditions that call for strong electron localization? Here, we show that the Fe sublattice is locally distorted and accommodates two kinds of Fe valence environments giving rise to a bimodal bond-distribution, with short and long Fe bonds. The bimodal bonds are present even as the system becomes superconducting in the presence of antiferromagnetism, with the weight continuously shifting from the short to the long with increasing K content. Such a hybrid state is most likely found in cuprates as well while our results point to the importance of the local atomic symmetry by which exchange interactions between local moments materialize. PMID:23782976

The hybrid lattice of K xFe 2-ySe 2: where superconductivity and magnetism coexist

DOE PAGES

Yang, Junjie; Duan, Chunruo; Huang, Qing; ...

2013-01-01

Much remains unknown of the microscopic origin of superconductivity in atomically disordered systems of amorphous alloys or in crystals riddled with defects. A manifestation of this conundrum is envisaged in the highly defective superconductor of K xFe 2-ySe 2. How can superconductivity survive under such crude conditions that call for strong electron localization? Here, we show that the Fe sublattice is locally distorted and accommodates two kinds of Fe valence environments giving rise to a bimodal bond-distribution, with short and long Fe bonds. The bimodal bonds are present even as the system becomes superconducting in the presence of antiferromagnetism, withmore » the weight continuously shifting from the short to the long with increasing K content. Such a hybrid state is most likely found in cuprates as well while our results point to the importance of the local atomic symmetry by which exchange interactions between local moments materialize.« less

Identification of phases, symmetries and defects through local crystallography

DOE PAGES

Belianinov, Alex; He, Qian; Kravchenko, Mikhail; ...

2015-07-20

Here we report that advances in electron and probe microscopies allow 10 pm or higher precision in measurements of atomic positions. This level of fidelity is sufficient to correlate the length (and hence energy) of bonds, as well as bond angles to functional properties of materials. Traditionally, this relied on mapping locally measured parameters to macroscopic variables, for example, average unit cell. This description effectively ignores the information contained in the microscopic degrees of freedom available in a high-resolution image. Here we introduce an approach for local analysis of material structure based on statistical analysis of individual atomic neighbourhoods. Clusteringmore » and multivariate algorithms such as principal component analysis explore the connectivity of lattice and bond structure, as well as identify minute structural distortions, thus allowing for chemical description and identification of phases. This analysis lays the framework for building image genomes and structure–property libraries, based on conjoining structural and spectral realms through local atomic behaviour.« less

Scanning electron microscope view of iron crystal growing on pyroxene crystal

NASA Technical Reports Server (NTRS)

1972-01-01

A scanning electron microscope photograph of a four-micron size iron crystal growing on a pyroxene crystal (calcium-magnesium-iron silicate) from the Apollo 15 Hadley-Apennino lunar landing site. The well developed crystal faces indicate that the crystal was formed from a hot vapor as the rock was cooling.

Arc-melting preparation of single crystal LaB.sub.6 cathodes

DOEpatents

Gibson, Edwin D.; Verhoeven, John D.

1977-06-21

A method for preparing single crystals of lanthanum hexaboride (LaB.sub.6) by arc melting a rod of compacted LaB.sub.6 powder. The method is especially suitable for preparing single crystal LaB.sub.6 cathodes for use in scanning electron microscopes (SEM) and scanning transmission electron microscopes (STEM).

Deciphering the physics and chemistry of perovskites with transmission electron microscopy.

PubMed

Polking, Mark J

2016-03-28

Perovskite oxides exhibit rich structural complexity and a broad range of functional properties, including ferroelectricity, ferromagnetism, and superconductivity. The development of aberration correction for the transmission electron microscope and concurrent progress in electron spectroscopy, electron holography, and other techniques has fueled rapid progress in the understanding of the physics and chemistry of these materials. New techniques based on the transmission electron microscope are first surveyed, and the applications of these techniques for the study of the structure, chemistry, electrostatics, and dynamics of perovskite oxides are then explored in detail, with a particular focus on ferroelectric materials.

Source brightness and useful beam current of carbon nanotubes and other very small emitters

NASA Astrophysics Data System (ADS)

Kruit, P.; Bezuijen, M.; Barth, J. E.

2006-01-01

The potential application of carbon nanotubes as electron sources in electron microscopes is analyzed. The resolution and probe current that can be obtained from a carbon nanotube emitter in a low-voltage scanning electron microscope are calculated and compared to the state of the art using Schottky electron sources. Many analytical equations for probe-size versus probe-current relations in different parameter regimes are obtained. It is shown that for most carbon nanotube emitters, the gun lens aberrations are larger than the emitters' virtual source size and thus restrict the microscope's performance. The result is that the advantages of the higher brightness of nanotube emitters are limited unless the angular emission current is increased over present day values or the gun lens aberrations are decreased. For some nanotubes with a closed cap, it is known that the emitted electron beam is coherent over the full emission cone. We argue that for such emitters the parameter ``brightness'' becomes meaningless. The influence of phase variations in the electron wave front emitted from such a nanotube emitter on the focusing of the electron beam is analyzed.

High-pressure freezing for scanning transmission electron tomography analysis of cellular organelles.

PubMed

Walther, Paul; Schmid, Eberhard; Höhn, Katharina

2013-01-01

Using an electron microscope's scanning transmission mode (STEM) for collection of tomographic datasets is advantageous compared to bright field transmission electron microscopic (TEM). For image formation, inelastic scattering does not cause chromatic aberration, since in STEM mode no image forming lenses are used after the beam has passed the sample, in contrast to regular TEM. Therefore, thicker samples can be imaged. It has been experimentally demonstrated that STEM is superior to TEM and energy filtered TEM for tomography of samples as thick as 1 μm. Even when using the best electron microscope, adequate sample preparation is the key for interpretable results. We adapted protocols for high-pressure freezing of cultivated cells from a physiological state. In this chapter, we describe optimized high-pressure freezing and freeze substitution protocols for STEM tomography in order to obtain high membrane contrast.

Transmission environmental scanning electron microscope with scintillation gaseous detection device.

PubMed

Danilatos, Gerasimos; Kollia, Mary; Dracopoulos, Vassileios

2015-03-01

A transmission environmental scanning electron microscope with use of a scintillation gaseous detection device has been implemented. This corresponds to a transmission scanning electron microscope but with addition of a gaseous environment acting both as environmental and detection medium. A commercial type of low vacuum machine has been employed together with appropriate modifications to the detection configuration. This involves controlled screening of various emitted signals in conjunction with a scintillation gaseous detection device already provided with the machine for regular surface imaging. Dark field and bright field imaging has been obtained along with other detection conditions. With a progressive series of modifications and tests, the theory and practice of a novel type of microscopy is briefly shown now ushering further significant improvements and developments in electron microscopy as a whole. Copyright © 2014 Elsevier B.V. All rights reserved.

Physics and engineering aspects of cell and tissue imaging systems: microscopic devices and computer assisted diagnosis.

PubMed

Chen, Xiaodong; Ren, Liqiang; Zheng, Bin; Liu, Hong

2013-01-01

The conventional optical microscopes have been used widely in scientific research and in clinical practice. The modern digital microscopic devices combine the power of optical imaging and computerized analysis, archiving and communication techniques. It has a great potential in pathological examinations for improving the efficiency and accuracy of clinical diagnosis. This chapter reviews the basic optical principles of conventional microscopes, fluorescence microscopes and electron microscopes. The recent developments and future clinical applications of advanced digital microscopic imaging methods and computer assisted diagnosis schemes are also discussed.

Analysis of microscopic parameters of surface charging in polymer caused by defocused electron beam irradiation.

PubMed

Liu, Jing; Zhang, Hai-Bo

2014-12-01

The relationship between microscopic parameters and polymer charging caused by defocused electron beam irradiation is investigated using a dynamic scattering-transport model. The dynamic charging process of an irradiated polymer using a defocused 30 keV electron beam is conducted. In this study, the space charge distribution with a 30 keV non-penetrating e-beam is negative and supported by some existing experimental data. The internal potential is negative, but relatively high near the surface, and it decreases to a maximum negative value at z=6 μm and finally tend to 0 at the bottom of film. The leakage current and the surface potential behave similarly, and the secondary electron and leakage currents follow the charging equilibrium condition. The surface potential decreases with increasing beam current density, trap concentration, capture cross section, film thickness and electron-hole recombination rate, but with decreasing electron mobility and electron energy. The total charge density increases with increasing beam current density, trap concentration, capture cross section, film thickness and electron-hole recombination rate, but with decreasing electron mobility and electron energy. This study shows a comprehensive analysis of microscopic factors of surface charging characteristics in an electron-based surface microscopy and analysis. Copyright © 2014 Elsevier Ltd. All rights reserved.

Fully kinetic simulations of collisionless, mesothermal plasma emission: Macroscopic plume structure and microscopic electron characteristics

NASA Astrophysics Data System (ADS)

Hu, Yuan; Wang, Joseph

2017-03-01

This paper presents a fully kinetic particle particle-in-cell simulation study on the emission of a collisionless plasma plume consisting of cold beam ions and thermal electrons. Results are presented for both the two-dimensional macroscopic plume structure and the microscopic electron kinetic characteristics. We find that the macroscopic plume structure exhibits several distinctive regions, including an undisturbed core region, an electron cooling expansion region, and an electron isothermal expansion region. The properties of each region are determined by microscopic electron kinetic characteristics. The division between the undisturbed region and the cooling expansion region approximately matches the Mach line generated at the edge of the emission surface, and that between the cooling expansion region and the isothermal expansion region approximately matches the potential well established in the beam. The interactions between electrons and the potential well lead to a new, near-equilibrium state different from the initial distribution for the electrons in the isothermal expansion region. The electron kinetic characteristics in the plume are also very anisotropic. As the electron expansion process is mostly non-equilibrium and anisotropic, the commonly used assumption that the electrons in a collisionless, mesothermal plasma plume may be treated as a single equilibrium fluid in general is not valid.

Sparse imaging for fast electron microscopy

NASA Astrophysics Data System (ADS)

Anderson, Hyrum S.; Ilic-Helms, Jovana; Rohrer, Brandon; Wheeler, Jason; Larson, Kurt

2013-02-01

Scanning electron microscopes (SEMs) are used in neuroscience and materials science to image centimeters of sample area at nanometer scales. Since imaging rates are in large part SNR-limited, large collections can lead to weeks of around-the-clock imaging time. To increase data collection speed, we propose and demonstrate on an operational SEM a fast method to sparsely sample and reconstruct smooth images. To accurately localize the electron probe position at fast scan rates, we model the dynamics of the scan coils, and use the model to rapidly and accurately visit a randomly selected subset of pixel locations. Images are reconstructed from the undersampled data by compressed sensing inversion using image smoothness as a prior. We report image fidelity as a function of acquisition speed by comparing traditional raster to sparse imaging modes. Our approach is equally applicable to other domains of nanometer microscopy in which the time to position a probe is a limiting factor (e.g., atomic force microscopy), or in which excessive electron doses might otherwise alter the sample being observed (e.g., scanning transmission electron microscopy).

Electronic properties of epitaxial silicene: a LT-STM/STS study

NASA Astrophysics Data System (ADS)

Fleurence, Antoine; Lee, Chi-Cheng; Ozaki, Taisuke; Yamada-Takamura, Yukiko; Yoshida, Yasuo; Hasegawa, Yukio

2013-03-01

The astonishing properties of silicene, the Si-counterpart of graphene, together with pioneering experimental observations, triggered in the very recent years, an exponentially increasing interest for this atom-thick material, both at fundamental level and for applications in high-speed electronic devices. We demonstrated, that the spontaneous segregation of silicon on (0001) surface of zirconium diboride (ZrB2) thin films epitaxied on Si(111) wafers gives rise to a wide-scale uniform two-dimensional silicene sheet. The silicene nature of the honeycomb structure imaged by scanning tunneling microscopy is evidenced by the observation of gap-opened π-electronic bands. The band gap opening is primarily due the specifically imprinted buckling. Here, we present the results of a low-temperature scanning tunneling spectroscopy investigation, which evidences the n-doped nature of silicene. The mapping of the local density of states, together with density functional theory give precious insights into the microscopic origin of the electronic bands of silicene. In particular, it shows the correlation between the degree of sp2 hybridization of different Si atoms in the internal structure and the character of the electronic bands.

Deformation-induced localized solid-state amorphization in nanocrystalline nickel.

PubMed

Han, Shuang; Zhao, Lei; Jiang, Qing; Lian, Jianshe

2012-01-01

Although amorphous structures have been widely obtained in various multi-component metallic alloys, amorphization in pure metals has seldom been observed and remains a long-standing scientific curiosity and technological interest. Here we present experimental evidence of localized solid-state amorphization in bulk nanocrystalline nickel introduced by quasi-static compression at room temperature. High-resolution electron microscope observations illustrate that nano-scale amorphous structures present at the regions where severe deformation occurred, e.g. along crack paths or surrounding nano-voids. These findings have indicated that nanocrystalline structures are highly desirable for promoting solid-state amorphization, which may provide new insights for understanding the nature of the crystalline-to-amorphous transformation and suggested a potential method to produce elemental metallic glasses that have hardly been available hitherto through rapid solidification.

Deformation-induced localized solid-state amorphization in nanocrystalline nickel

PubMed Central

Han, Shuang; Zhao, Lei; Jiang, Qing; Lian, Jianshe

2012-01-01

Although amorphous structures have been widely obtained in various multi-component metallic alloys, amorphization in pure metals has seldom been observed and remains a long-standing scientific curiosity and technological interest. Here we present experimental evidence of localized solid-state amorphization in bulk nanocrystalline nickel introduced by quasi-static compression at room temperature. High-resolution electron microscope observations illustrate that nano-scale amorphous structures present at the regions where severe deformation occurred, e.g. along crack paths or surrounding nano-voids. These findings have indicated that nanocrystalline structures are highly desirable for promoting solid-state amorphization, which may provide new insights for understanding the nature of the crystalline-to-amorphous transformation and suggested a potential method to produce elemental metallic glasses that have hardly been available hitherto through rapid solidification. PMID:22768383

Microscopic Approach to Magnetism and Superconductivity of f-Electron Systems with Filled Skutterudite Structure

NASA Astrophysics Data System (ADS)

Hotta, Takashi

2005-04-01

In order to gain a deep insight into f-electron properties of filled skutterudite compounds from a microscopic viewpoint, we investigate the multiorbital Anderson model including Coulomb interactions, spin-orbit coupling, and crystalline electric field effect. First we examine the local f-electron state in detail in comparison with the results of LS and j-j coupling schemes. For each case of n=1--13, where n is the number of f electrons per rare-earth ion, the model is analyzed by using the numerical renormalization group (NRG) method to evaluate magnetic susceptibility and entropy of f electron. In particular, for the f 2-electron system corresponding to the Pr-based filled skutterudite, it is found that magnetic fluctuations significantly remain at low temperatures, even when the ground state is Γ1 singlet, if Γ_4(2) triplet is the excited state with small excitation energy. In order to make further step to construct a simplified model which can be treated even in a periodic system, we also analyze the Anderson model constructed based on the j-j coupling scheme by using the NRG method. It is clearly observed that the magnetic properties are quite similar to those of the original Anderson model. Then, we construct an orbital degenerate Hubbard model based on the j-j coupling scheme to investigate the mechanism of superconductivity of filled skutterudites. In the 2-site model, we carefully evaluate the superconducting pair susceptibility for the case of n=2 and find that the susceptibility for off-site Cooper pair is clearly enhanced only in a transition region in which the singlet and triplet ground states are interchanged. We envision a scenario that unconventional superconductivity induced by magnetic fluctuations may occur in the f 2-electron system with Γ1 ground state such as Pr-based filled skutterudite compounds.

Analysis with electron microscope of multielement samples using pure element standards

DOEpatents

King, Wayne E.

1987-01-01

A method and modified analytical electron microscope for determining the concentration of elements in a multielement sample by exposing samples with differing thicknesses for each element to a beam of electrons, simultaneously measuring the electron dosage and x-ray intensities for each sample of element to determine a "K.sub.AB " value to be used in the equation ##EQU1## where I is intensity and C is concentration for elements A and B, and exposing the multielement sample to determine the concentrations of the elements in the sample.

Rapid and precise scanning helium ion microscope milling of solid-state nanopores for biomolecule detection.

PubMed

Yang, Jijin; Ferranti, David C; Stern, Lewis A; Sanford, Colin A; Huang, Jason; Ren, Zheng; Qin, Lu-Chang; Hall, Adam R

2011-07-15

We report the formation of solid-state nanopores using a scanning helium ion microscope. The fabrication process offers the advantage of high sample throughput along with fine control over nanopore dimensions, producing single pores with diameters below 4 nm. Electronic noise associated with ion transport through the resultant pores is found to be comparable with levels measured on devices made with the established technique of transmission electron microscope milling. We demonstrate the utility of our nanopores for biomolecular analysis by measuring the passage of double-strand DNA.

Intrinsic instability of aberration-corrected electron microscopes.

PubMed

Schramm, S M; van der Molen, S J; Tromp, R M

2012-10-19

Aberration-corrected microscopes with subatomic resolution will impact broad areas of science and technology. However, the experimentally observed lifetime of the corrected state is just a few minutes. Here we show that the corrected state is intrinsically unstable; the higher its quality, the more unstable it is. Analyzing the contrast transfer function near optimum correction, we define an "instability budget" which allows a rational trade-off between resolution and stability. Unless control systems are developed to overcome these challenges, intrinsic instability poses a fundamental limit to the resolution practically achievable in the electron microscope.

In situ nanomechanical testing of twinned metals in a transmission electron microscope

DOE PAGES

Li, Nan; Wang, Jiangwei; Mao, Scott; ...

2016-04-01

This paper focuses on in situ transmission electron microscope (TEM) characterization to explore twins in face-centered-cubic and body-centered-cubic monolithic metals, and their impact on the overall mechanical performance. Taking advantage of simultaneous nanomechanical deformation and nanoscale imaging using versatile in situ TEM tools, direct correlation of these unique microscopic defects with macroscopic mechanical performance becomes possible. This article summarizes recent evidence to support the mechanisms related to strengthening and plasticity in metals, including nanotwinned Cu, Ni, Al, Au, and others in bulk, thin film, and nanowire forms.

In situ nanomechanical testing of twinned metals in a transmission electron microscope

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Nan; Wang, Jiangwei; Mao, Scott

This paper focuses on in situ transmission electron microscope (TEM) characterization to explore twins in face-centered-cubic and body-centered-cubic monolithic metals, and their impact on the overall mechanical performance. Taking advantage of simultaneous nanomechanical deformation and nanoscale imaging using versatile in situ TEM tools, direct correlation of these unique microscopic defects with macroscopic mechanical performance becomes possible. This article summarizes recent evidence to support the mechanisms related to strengthening and plasticity in metals, including nanotwinned Cu, Ni, Al, Au, and others in bulk, thin film, and nanowire forms.

Electron beam dynamics in an ultrafast transmission electron microscope with Wehnelt electrode.

PubMed

Bücker, K; Picher, M; Crégut, O; LaGrange, T; Reed, B W; Park, S T; Masiel, D J; Banhart, F

2016-12-01

High temporal resolution transmission electron microscopy techniques have shown significant progress in recent years. Using photoelectron pulses induced by ultrashort laser pulses on the cathode, these methods can probe ultrafast materials processes and have revealed numerous dynamic phenomena at the nanoscale. Most recently, the technique has been implemented in standard thermionic electron microscopes that provide a flexible platform for studying material's dynamics over a wide range of spatial and temporal scales. In this study, the electron pulses in such an ultrafast transmission electron microscope are characterized in detail. The microscope is based on a thermionic gun with a Wehnelt electrode and is operated in a stroboscopic photoelectron mode. It is shown that the Wehnelt bias has a decisive influence on the temporal and energy spread of the picosecond electron pulses. Depending on the shape of the cathode and the cathode-Wehnelt distance, different emission patterns with different pulse parameters are obtained. The energy spread of the pulses is determined by space charge and Boersch effects, given by the number of electrons in a pulse. However, filtering effects due to the chromatic aberrations of the Wehnelt electrode allow the extraction of pulses with narrow energy spreads. The temporal spread is governed by electron trajectories of different length and in different electrostatic potentials. High temporal resolution is obtained by excluding shank emission from the cathode and aberration-induced halos in the emission pattern. By varying the cathode-Wehnelt gap, the Wehnelt bias, and the number of photoelectrons in a pulse, tradeoffs between energy and temporal resolution as well as beam intensity can be made as needed for experiments. Based on the characterization of the electron pulses, the optimal conditions for the operation of ultrafast TEMs with thermionic gun assembly are elaborated. Copyright © 2016 Elsevier B.V. All rights reserved.

Anisotropy of Spin Fluctuations in a Tetragonal Heavy Fermion Antiferromagnet CeRhAl 4 Si 2

DOE PAGES

Sakai, H.; Hattori, T.; Tokunaga, Y.; ...

2017-06-01

An antiferromagnetic (AFM) Kondo lattice compound CeRhAl 4Si 2, which exhibits successive AFM transitions at T N1=14 K and T N2=9 K in zero external field, has been microscopically investigated by means of 27Al nuclear magnetic resonance (NMR) technique. In the high temperature range, magnetic excitations of 4f electrons can be well explained by isotropic localized spin fluctuations. Below ~50 K, it begins to show a characteristic anisotropy of spin fluctuations, which suggests a competition between spin fluctuations and nesting instability in this system.

Doxorubicin-loaded Zein in situ gel for interstitial chemotherapy.

PubMed

Cao, Xiaoying; Geng, Jianning; Su, Suwen; Zhang, Linan; Xu, Qian; Zhang, Li; Xie, Yinghua; Wu, Shaomei; Sun, Yongjun; Gao, Zibin

2012-01-01

A novel drug delivery system of doxorubicin (DOX)-loaded Zein in situ gel for interstitial chemotherapy was investigated in this study. The possible mechanisms of drug release were described according to morphological analysis by optical microscopy and scanning electronic microscope (SEM). In vitro and in vivo anti-tumor activity studies showed that DOX-loaded Zein in situ gel was superior to DOX solution. Local pharmacokinetics in tumor tissue was studied by quantitative analysis with confocal laser scanning microscopy (CLSM) combined with microdialysis technology. A pharmacokinetics mathematical model of DOX-loaded Zein in situ gel in tumors was then built.

Initiation of Collapsing Pentacene Crystal by Au

NASA Astrophysics Data System (ADS)

Ihm, Kyuwook; Lee, Kyoung-Jae; Chung, Sukmin; Kang, Tai-Hee

2011-12-01

Metal contacts with gold on organics are an essential factor in organic electronics. The unveiled key challenge is to probe dynamic details of the microscopic evolution of the organic crystal when the atomic Au is introduced. Here, we show how the collapse of the pentacene crystal is initiated even by a few Au atoms. Our photoemission and x-ray absorption results indicate that the gentle decoupling of intra and inter-molecular π-π interactions causes the localization of the lowest unoccupied molecular orbital as well as the removal of cohesive forces between molecules, leading to the subsequent crystal collapse.

Dose-rate-dependent damage of cerium dioxide in the scanning transmission electron microscope.

PubMed

Johnston-Peck, Aaron C; DuChene, Joseph S; Roberts, Alan D; Wei, Wei David; Herzing, Andrew A

2016-11-01

Beam damage caused by energetic electrons in the transmission electron microscope is a fundamental constraint limiting the collection of artifact-free information. Through understanding the influence of the electron beam, experimental routines may be adjusted to improve the data collection process. Investigations of CeO 2 indicate that there is not a critical dose required for the accumulation of electron beam damage. Instead, measurements using annular dark field scanning transmission electron microscopy and electron energy loss spectroscopy demonstrate that the onset of measurable damage occurs when a critical dose rate is exceeded. The mechanism behind this phenomenon is that oxygen vacancies created by exposure to a 300keV electron beam are actively annihilated as the sample re-oxidizes in the microscope environment. As a result, only when the rate of vacancy creation exceeds the recovery rate will beam damage begin to accumulate. This observation suggests that dose-intensive experiments can be accomplished without disrupting the native structure of the sample when executed using dose rates below the appropriate threshold. Furthermore, the presence of an encapsulating carbonaceous layer inhibits processes that cause beam damage, markedly increasing the dose rate threshold for the accumulation of damage. Published by Elsevier B.V.

Dose-rate-dependent damage of cerium dioxide in the scanning transmission electron microscope

PubMed Central

Johnston-Peck, Aaron C.; DuChene, Joseph S.; Roberts, Alan D.; Wei, Wei David; Herzing, Andrew A.

2016-01-01

Beam damage caused by energetic electrons in the transmission electron microscope is a fundamental constraint limiting the collection of artifact-free information. Through understanding the influence of the electron beam, experimental routines may be adjusted to improve the data collection process. Investigations of CeO2 indicate that there is not a critical dose required for the accumulation of electron beam damage. Instead, measurements using annular dark field scanning transmission electron microscopy and electron energy loss spectroscopy demonstrate that the onset of measurable damage occurs when a critical dose rate is exceeded. The mechanism behind this phenomenon is that oxygen vacancies created by exposure to a 300 keV electron beam are actively annihilated as the sample re-oxidizes in the microscope environment. As a result, only when the rate of vacancy creation exceeds the recovery rate will beam damage begin to accumulate. This observation suggests that dose-intensive experiments can be accomplished without disrupting the native structure of the sample when executed using dose rates below the appropriate threshold. Furthermore, the presence of an encapsulating carbonaceous layer inhibits processes that cause beam damage, markedly increasing the dose rate threshold for the accumulation of damage. PMID:27469265

Qualitative and quantitative interpretation of SEM image using digital image processing.

PubMed

Saladra, Dawid; Kopernik, Magdalena

2016-10-01

The aim of the this study is improvement of qualitative and quantitative analysis of scanning electron microscope micrographs by development of computer program, which enables automatic crack analysis of scanning electron microscopy (SEM) micrographs. Micromechanical tests of pneumatic ventricular assist devices result in a large number of micrographs. Therefore, the analysis must be automatic. Tests for athrombogenic titanium nitride/gold coatings deposited on polymeric substrates (Bionate II) are performed. These tests include microshear, microtension and fatigue analysis. Anisotropic surface defects observed in the SEM micrographs require support for qualitative and quantitative interpretation. Improvement of qualitative analysis of scanning electron microscope images was achieved by a set of computational tools that includes binarization, simplified expanding, expanding, simple image statistic thresholding, the filters Laplacian 1, and Laplacian 2, Otsu and reverse binarization. Several modifications of the known image processing techniques and combinations of the selected image processing techniques were applied. The introduced quantitative analysis of digital scanning electron microscope images enables computation of stereological parameters such as area, crack angle, crack length, and total crack length per unit area. This study also compares the functionality of the developed computer program of digital image processing with existing applications. The described pre- and postprocessing may be helpful in scanning electron microscopy and transmission electron microscopy surface investigations. © 2016 The Authors Journal of Microscopy © 2016 Royal Microscopical Society.

[Microscopic investigation of vessel wall after endovascular catheter atherectomy].

PubMed

Tsygankov, V N; Khovalkin, R G; Chekmareva, I A; Kalinin, D V; Filippova, E M

2014-01-01

Endovascular target catheter atherectomy (ETCA) - method of artery patency allowing to obtain occlusion substrate. Given the high destructive effect of atherectome's elements on tissue the objective was determination possibility of histological and electron microscopic investigation of this substrate after atherectomy. The research included 8 patients who underwent ETCA of legs arteries. It was observed substrate removal from broken stent in 1 case. 2 of 8 patients had diabetes. Obtained substrate was available for histological and electron microscopic investigation. Atherosclerosis was confirmed in all cases. It was not observed substrate significant morphological changes in patients with presence or absence of diabetes. Microscopic investigation of substrate from broken stent shows pronounced development of granulation tissue that was regarded as special form of reparative regeneration. Finding internal elastic membrane during microscopic investigation in some cases proves radical intervention. The authors consider that microscopic investigation of substrate after ETCA may be used for diagnosis verification, thorough analysis of morphological changes in lesion area and radicalism of atherectomy.

In Situ Microstructural Control and Mechanical Testing Inside the Transmission Electron Microscope at Elevated Temperatures

NASA Astrophysics Data System (ADS)

Wang, Baoming; Haque, M. A.

2015-08-01

With atomic-scale imaging and analytical capabilities such as electron diffraction and energy-loss spectroscopy, the transmission electron microscope has allowed access to the internal microstructure of materials like no other microscopy. It has been mostly a passive or post-mortem analysis tool, but that trend is changing with in situ straining, heating and electrical biasing. In this study, we design and demonstrate a multi-functional microchip that integrates actuators, sensors, heaters and electrodes with freestanding electron transparent specimens. In addition to mechanical testing at elevated temperatures, the chip can actively control microstructures (grain growth and phase change) of the specimen material. Using nano-crystalline aluminum, nickel and zirconium as specimen materials, we demonstrate these novel capabilities inside the microscope. Our approach of active microstructural control and quantitative testing with real-time visualization can influence mechanistic modeling by providing direct and accurate evidence of the fundamental mechanisms behind materials behavior.

Isotope analysis in the transmission electron microscope.

PubMed

Susi, Toma; Hofer, Christoph; Argentero, Giacomo; Leuthner, Gregor T; Pennycook, Timothy J; Mangler, Clemens; Meyer, Jannik C; Kotakoski, Jani

2016-10-10

The Ångström-sized probe of the scanning transmission electron microscope can visualize and collect spectra from single atoms. This can unambiguously resolve the chemical structure of materials, but not their isotopic composition. Here we differentiate between two isotopes of the same element by quantifying how likely the energetic imaging electrons are to eject atoms. First, we measure the displacement probability in graphene grown from either 12 C or 13 C and describe the process using a quantum mechanical model of lattice vibrations coupled with density functional theory simulations. We then test our spatial resolution in a mixed sample by ejecting individual atoms from nanoscale areas spanning an interface region that is far from atomically sharp, mapping the isotope concentration with a precision better than 20%. Although we use a scanning instrument, our method may be applicable to any atomic resolution transmission electron microscope and to other low-dimensional materials.

Microscopic Perspective on Photovoltaic Reciprocity in Ultrathin Solar Cells

NASA Astrophysics Data System (ADS)

Aeberhard, Urs; Rau, Uwe

2017-06-01

The photovoltaic reciprocity theory relates the electroluminescence spectrum of a solar cell under applied bias to the external photovoltaic quantum efficiency of the device as measured at short circuit conditions. Its derivation is based on detailed balance relations between local absorption and emission rates in optically isotropic media with nondegenerate quasiequilibrium carrier distributions. In many cases, the dependence of density and spatial variation of electronic and optical device states on the point of operation is modest and the reciprocity relation holds. In nanostructure-based photovoltaic devices exploiting confined modes, however, the underlying assumptions are no longer justifiable. In the case of ultrathin absorber solar cells, the modification of the electronic structure with applied bias is significant due to the large variation of the built-in field. Straightforward use of the external quantum efficiency as measured at short circuit conditions in the photovoltaic reciprocity theory thus fails to reproduce the electroluminescence spectrum at large forward bias voltage. This failure is demonstrated here by numerical simulation of both spectral quantities at normal incidence and emission for an ultrathin GaAs p -i -n solar cell using an advanced quantum kinetic formalism based on nonequilibrium Green's functions of coupled photons and charge carriers. While coinciding with the semiclassical relations under the conditions of their validity, the theory provides a consistent microscopic relationship between absorption, emission, and charge carrier transport in photovoltaic devices at arbitrary operating conditions and for any shape of optical and electronic density of states.

Microscopic Perspective on Photovoltaic Reciprocity in Ultrathin Solar Cells.

PubMed

Aeberhard, Urs; Rau, Uwe

2017-06-16

The photovoltaic reciprocity theory relates the electroluminescence spectrum of a solar cell under applied bias to the external photovoltaic quantum efficiency of the device as measured at short circuit conditions. Its derivation is based on detailed balance relations between local absorption and emission rates in optically isotropic media with nondegenerate quasiequilibrium carrier distributions. In many cases, the dependence of density and spatial variation of electronic and optical device states on the point of operation is modest and the reciprocity relation holds. In nanostructure-based photovoltaic devices exploiting confined modes, however, the underlying assumptions are no longer justifiable. In the case of ultrathin absorber solar cells, the modification of the electronic structure with applied bias is significant due to the large variation of the built-in field. Straightforward use of the external quantum efficiency as measured at short circuit conditions in the photovoltaic reciprocity theory thus fails to reproduce the electroluminescence spectrum at large forward bias voltage. This failure is demonstrated here by numerical simulation of both spectral quantities at normal incidence and emission for an ultrathin GaAs p-i-n solar cell using an advanced quantum kinetic formalism based on nonequilibrium Green's functions of coupled photons and charge carriers. While coinciding with the semiclassical relations under the conditions of their validity, the theory provides a consistent microscopic relationship between absorption, emission, and charge carrier transport in photovoltaic devices at arbitrary operating conditions and for any shape of optical and electronic density of states.

Mucinous colorectal adenocarcinoma with signet-ring cells: immunohistochemical and ultrastructural study.

PubMed

Seretis, E; Konstantinidou, A; Arnogiannakis, N; Xinopoulos, D; Voloudakis-Baltatzis, I E

2010-12-01

A primary mucinous colorectal adenocarcinoma tissue with signet-ring cells, as revealed after histological evaluation, was examined ultrastructurally. The authors also analyzed the immunohistochemical data of the tissue for serotonin, vasoactive intestinal polypeptide (VIP), bombesin, somatostatin, and glucagon, using the peroxidase anti-peroxidase (PAP) method and the immunogold labeling method for light and electron microscope, respectively. Electron microscopically mucinous adenocarcinoma was characterized by the formation of small lumen. Adenocarcinoma cells were full of mucous granules of varying electron density, providing a good environment for the tumor cells to grow. They also exhibited a significant loss of microvilli and intracytoplasmic junctions, which could allow the cells to disseminate. Signet-ring cells were located in the basal site of the ducts or in the lamina propria and appeared neoplastic, with mucin accumulation intracellularly and an eccentric crescent-shaped nucleus. The cytoplasmic organelles were decreased and at the periphery of the cell. The PAP method demonstrated that these cells were strongly positive for bombesin and also positive for vasointestinal polypeptide (VIP). The immunogold method detected bombesin immunoreactivity in the vacuoles as well as in other cytoplasmic membranes, whereas VIP was localized mainly in the plasma membrane. The location of signet-ring cells combined with the immunoreactivity for bombesin and VIP indicated that signet-ring cells were of neuroendocrine origin and probably dedifferentiated enterochromaffin-like endocrine cells. These findings have implications for understanding the biological behavior of these composite malignant tumors and could help in the knowledge of the origin of signet-ring cells.

Resolving the Spatial Structures of Bound Hole States in Black Phosphorus.

PubMed

Qiu, Zhizhan; Fang, Hanyan; Carvalho, Alexandra; Rodin, A S; Liu, Yanpeng; Tan, Sherman J R; Telychko, Mykola; Lv, Pin; Su, Jie; Wang, Yewu; Castro Neto, A H; Lu, Jiong

2017-11-08

Understanding the local electronic properties of individual defects and dopants in black phosphorus (BP) is of great importance for both fundamental research and technological applications. Here, we employ low-temperature scanning tunnelling microscope (LT-STM) to probe the local electronic structures of single acceptors in BP. We demonstrate that the charge state of individual acceptors can be reversibly switched by controlling the tip-induced band bending. In addition, acceptor-related resonance features in the tunnelling spectra can be attributed to the formation of Rydberg-like bound hole states. The spatial mapping of the quantum bound states shows two distinct shapes evolving from an extended ellipse shape for the 1s ground state to a dumbbell shape for the 2p x excited state. The wave functions of bound hole states can be well-described using the hydrogen-like model with anisotropic effective mass, corroborated by our theoretical calculations. Our findings not only provide new insight into the many-body interactions around single dopants in this anisotropic two-dimensional material but also pave the way to the design of novel quantum devices.

Scanning Electron Microscopy (SEM) Procedure for HE Powders on a Zeiss Sigma HD VP SEM

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zaka, F.

This method describes the characterization of inert and HE materials by the Zeiss Sigma HD VP field emission Scanning Electron Microscope (SEM). The SEM uses an accelerated electron beam to generate high-magnification images of explosives and other materials. It is fitted with five detectors (SE, Inlens, STEM, VPSE, HDBSD) to enable imaging of the sample via different secondary electron signatures, angles, and energies. In addition to imaging through electron detection, the microscope is also fitted with two Oxford Instrument Energy Dispersive Spectrometer (EDS) 80 mm detectors to generate elemental constituent spectra and two-dimensional maps of the material being scanned.

Microscopic investigation of cavitation erosion damage in metals

NASA Technical Reports Server (NTRS)

Hackworh, J. V.; Adler, W. F.

1974-01-01

The results of research to identify the cavitation erosion damage mechanisms at the microscopic level for three metals (aluminum, stainless steel, and titanium) representing a range of properties and microstructure are presented. The metals were exposed to cavitation generated in distilled water by a 20-kHz ultrasonic facility operating at a vibration amplitude of 2 mils. Representative properties of the metals and experimental details are summarized. Replicas of the eroded surfaces of the specimens obtained periodically during exposure were examined with a transmission electron microscope to follow progression of the erosion damage and identify dominant erosion mechanisms as a function of exposure time. Eroded surfaces of selected specimens were also examined with a scanning electron microscope to assist in the interpretation.

Method and apparatus for a high-resolution three dimensional confocal scanning transmission electron microscope

DOEpatents

de Jonge, Niels [Oak Ridge, TN

2010-08-17

A confocal scanning transmission electron microscope which includes an electron illumination device providing an incident electron beam propagating in a direction defining a propagation axis, and a precision specimen scanning stage positioned along the propagation axis and movable in at least one direction transverse to the propagation axis. The precision specimen scanning stage is configured for positioning a specimen relative to the incident electron beam. A projector lens receives a transmitted electron beam transmitted through at least part of the specimen and focuses this transmitted beam onto an image plane, where the transmitted beam results from the specimen being illuminated by the incident electron beam. A detection system is placed approximately in the image plane.

Electron microscope phase enhancement

DOEpatents

Jin, Jian; Glaeser, Robert M.

2010-06-15

A microfabricated electron phase shift element is used for modifying the phase characteristics of an electron beam passing though its center aperture, while not affecting the more divergent portion of an incident beam to selectively provide a ninety-degree phase shift to the unscattered beam in the back focal plan of the objective lens, in order to realize Zernike-type, in-focus phase contrast in an electron microscope. One application of the element is to increase the contrast of an electron microscope for viewing weakly scattering samples while in focus. Typical weakly scattering samples include biological samples such as macromolecules, or perhaps cells. Preliminary experimental images demonstrate that these devices do apply a ninety degree phase shift as expected. Electrostatic calculations have been used to determine that fringing fields in the region of the scattered electron beams will cause a negligible phase shift as long as the ratio of electrode length to the transverse feature-size aperture is about 5:1. Calculations are underway to determine the feasibility of aspect smaller aspect ratios of about 3:1 and about 2:1.

Cellular distribution of uranium after acute exposure of renal epithelial cells: SEM, TEM and nuclear microscopy analysis

NASA Astrophysics Data System (ADS)

Carrière, Marie; Gouget, Barbara; Gallien, Jean-Paul; Avoscan, Laure; Gobin, Renée; Verbavatz, Jean-Marc; Khodja, Hicham

2005-04-01

The major health effect of uranium exposure has been reported to be chemical kidney toxicity, functional and histological damages being mainly observed in proximal tubule cells. Uranium enters the proximal tubule as uranyl-bicarbonate or uranyl-citrate complexes. The aim of our research is to investigate the mechanisms of uranium toxicity, intracellular accumulation and repartition after acute intoxication of rat renal proximal tubule epithelial cells, as a function of its chemical form. Microscopic observations of renal epithelial cells after acute exposure to uranyl-bicarbonate showing the presence of intracellular precipitates as thin needles of uranyl-phosphate localized in cell lysosomes have been published. However the initial site of precipitates formation has not been identified yet: they could either be formed outside the cells before internalization, or directly inside the cells. Uranium solubility as a function and initial concentration was specified by ICP-MS analysis of culture media. In parallel, uranium uptake and distribution in cell monolayers exposed to U-bicarbonate was investigated by nuclear microprobe analyses. Finally, the presence of uranium precipitates was tested out by scanning electron microscopic observations (SEM), while extracellular and/or intracellular precipitates were observed on thin sections of cells by transmission electron microscopy (TEM).

Ion irradiation synthesis of Ag–Au bimetallic nanospheroids in SiO{sub 2} glass substrate with tunable surface plasmon resonance frequency

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meng, Xuan; Yu, Ruixuan; Takayanagi, Shinya

2013-08-07

Ag–Au bimetallic nanospheroids with tunable localized surface plasmon resonance (LSPR) were synthesized by 100 keV Ar–ion irradiation of 30 nm Ag–Au bimetallic films deposited on SiO{sub 2} glass substrates. A shift of the LSPR peaks toward shorter wavelengths was observed up to an irradiation fluence of 1.0 × 10{sup 17} cm{sup −2}, and then shifted toward the longer wavelength because of the increase of fragment volume under ion irradiation. Further control of LSPR frequency over a wider range was realized by modifying the chemical components. The resulting LSPR frequencies lie between that of the pure components, and an approximate linearmore » shift of the LSPR toward the longer wavelength with the Au concentration was achieved, which is in good agreement with the theoretical calculations based on Gans theory. In addition, the surface morphology and compositions were examined with a scanning electron microscope equipped with an energy dispersive spectrometer, and microstructural characterizations were performed using a transmission electron microscope. The formation of isolated photosensitive Ag–Au nanospheroids with a FCC structure partially embedded in the SiO{sub 2} substrate was confirmed, which has a potential application in solid-state devices.« less

Mars Life? - Microscopic Structures

NASA Image and Video Library

1996-08-09

In the center of this electron microscope image of a small chip from a meteorite are several tiny structures that are possible microscopic fossils of primitive, bacteria-like organisms that may have lived on Mars more than 3.6 billion years ago. http://photojournal.jpl.nasa.gov/catalog/PIA00283

Multi-Scale Investigation of the Formation and Breakdown of Passive Films on Carbon Steel Rebar in Concrete

NASA Astrophysics Data System (ADS)

Ghods, Pouria

The multi-scale investigation presented in this thesis was carried out to understand better the mechanisms of passivation and chloride-induced depassivation of carbon steel reinforcement in concrete. The study consisted of electrochemical experiments (electrochemical impedance spectroscopy, linear polarization resistance, free corrosion potential, anodic polarization), microscopic examinations (scanning electron microscopy, transmission electron microscopy, selected area diffraction, convergent beam electron diffraction), numerical modeling (finite element method), and spectroscopic studies (x-ray photoelectron, energy dispersed x-ray, electron energy loss). Electrochemical and microscopic studies showed that the composition of the pore solution and the surface conditions of the rebar affect the passivity and depassivation of carbon steel in concrete. It was demonstrated that crevices between mill scale and steel may become potential sites for depassivation and pit nucleation. The numerical investigation that was carried out to test this hypothesis confirmed that the ratio of chloride to hydroxide concentrations, Cl-/OH-, in crevices increased to levels higher than that of the bulk pore solution, making crevices more vulnerable to depassivation. Therefore, it was concluded that the variability associated with reported chloride thresholds might be attributed, at least in part, to the variability in mill scale properties resulting from the variability in manufacturing. The nano-scale microscopic and spectroscopic studies indicated the formation of 4-10 nm-thick passive oxide films on carbon steel in simulated concrete pore solutions, and these films consisted of two layers separated with an indistinct border. The inner layer was mainly composed of protective Fe2+-rich oxides that are in epitaxial relationship with the underlying steel surface; while the outer layer mostly consisted of (possibly porous) Fe3+-rich oxides, through which chlorides can penetrate. It was proposed that, in the presence of chlorides, Fe+2-rich oxides in the inner layer transform into Fe+3-rich oxides and potentially become un-protective. Although how this transformation occurs is still subject of future research, there are evidences showing that the process most likely leads to the formation of local anodic and cathodic sites on the steel surface.

Plasma column and nano-powder generation from solid titanium by localized microwaves in air

DOE Office of Scientific and Technical Information (OSTI.GOV)

Popescu, Simona; Jerby, Eli, E-mail: jerby@eng.tau.ac.il; Meir, Yehuda

2015-07-14

This paper studies the effect of a plasma column ejected from solid titanium by localized microwaves in an ambient air atmosphere. Nanoparticles of titanium dioxide (titania) are found to be directly synthesized in this plasma column maintained by the microwave energy in the cavity. The process is initiated by a hotspot induced by localized microwaves, which melts the titanium substrate locally. The molten hotspot emits ionized titanium vapors continuously into the stable plasma column, which may last for more than a minute duration. The characterization of the dusty plasma obtained is performed in-situ by small-angle X-ray scattering (SAXS), optical spectroscopy,more » and microwave reflection analyses. The deposited titania nanoparticles are structurally and morphologically analyzed by ex-situ optical and scanning-electron microscope observations, and also by X-ray diffraction. Using the Boltzmann plot method combined with the SAXS results, the electron temperature and density in the dusty plasma are estimated as ∼0.4 eV and ∼10{sup 19 }m{sup −3}, respectively. The analysis of the plasma product reveals nanoparticles of titania in crystalline phases of anatase, brookite, and rutile. These are spatially arranged in various spherical, cubic, lamellar, and network forms. Several applications are considered for this process of titania nano-powder production.« less

Concurrent in situ ion irradiation transmission electron microscope

DOE PAGES

Hattar, K.; Bufford, D. C.; Buller, D. L.

2014-08-29

An in situ ion irradiation transmission electron microscope has been developed and is operational at Sandia National Laboratories. This facility permits high spatial resolution, real time observation of electron transparent samples under ion irradiation, implantation, mechanical loading, corrosive environments, and combinations thereof. This includes the simultaneous implantation of low-energy gas ions (0.8–30 keV) during high-energy heavy ion irradiation (0.8–48 MeV). In addition, initial results in polycrystalline gold foils are provided to demonstrate the range of capabilities.

Directed polymers on a disordered tree with a defect subtree

NASA Astrophysics Data System (ADS)

Madras, Neal; Yıldırım, Gökhan

2018-04-01

We study the question of how the competition between bulk disorder and a localized microscopic defect affects the macroscopic behavior of a system in the directed polymer context at the free energy level. We consider the directed polymer model on a disordered d-ary tree and represent the localized microscopic defect by modifying the disorder distribution at each vertex in a single path (branch), or in a subtree, of the tree. The polymer must choose between following the microscopic defect and finding the best branches through the bulk disorder. We describe three possible phases, called the fully pinned, partially pinned and depinned phases. When the microscopic defect is associated only with a single branch, we compute the free energy and the critical curve of the model, and show that the partially pinned phase does not occur. When the localized microscopic defect is associated with a non-disordered regular subtree of the disordered tree, the picture is more complicated. We prove that all three phases are non-empty below a critical temperature, and that the partially pinned phase disappears above the critical temperature.

Water network-mediated, electron-induced proton transfer in [C5H5N ṡ (H2O)n]- clusters

NASA Astrophysics Data System (ADS)

DeBlase, Andrew F.; Wolke, Conrad T.; Weddle, Gary H.; Archer, Kaye A.; Jordan, Kenneth D.; Kelly, John T.; Tschumper, Gregory S.; Hammer, Nathan I.; Johnson, Mark A.

2015-10-01

The role of proton-assisted charge accommodation in electron capture by a heterocyclic electron scavenger is investigated through theoretical analysis of the vibrational spectra of cold, gas phase [Py ṡ (H2O)n=3-5]- clusters. These radical anions are formed when an excess electron is attached to water clusters containing a single pyridine (Py) molecule in a supersonic jet ion source. Under these conditions, the cluster ion distribution starts promptly at n = 3, and the photoelectron spectra, combined with vibrational predissociation spectra of the Ar-tagged anions, establish that for n > 3, these species are best described as hydrated hydroxide ions with the neutral pyridinium radical, PyH(0), occupying one of the primary solvation sites of the OH-. The n = 3 cluster appears to be a special case where charge localization on Py and hydroxide is nearly isoenergetic, and the nature of this species is explored with ab initio molecular dynamics calculations of the trajectories that start from metastable arrangements of the anion based on a diffuse, essentially dipole-bound electron. These calculations indicate that the reaction proceeds via a relatively slow rearrangement of the water network to create a favorable hydration configuration around the water molecule that eventually donates a proton to the Py nitrogen atom to yield the product hydroxide ion. The correlation between the degree of excess charge localization and the evolving shape of the water network revealed by this approach thus provides a microscopic picture of the "solvent coordinate" at the heart of a prototypical proton-coupled electron transfer reaction.

Measurement of Magnetic Exchange in Asymmetric Lanthanide Dimetallics: Toward a Transferable Theoretical Framework.

PubMed

Giansiracusa, Marcus J; Moreno-Pineda, Eufemio; Hussain, Riaz; Marx, Raphael; Martínez Prada, María; Neugebauer, Petr; Al-Badran, Susan; Collison, David; Tuna, Floriana; van Slageren, Joris; Carretta, Stefano; Guidi, Tatiana; McInnes, Eric J L; Winpenny, Richard E P; Chilton, Nicholas F

2018-02-21

Magnetic exchange interactions within the asymmetric dimetallic compounds [hqH 2 ][Ln 2 (hq) 4 (NO 3 ) 3 ]·MeOH, (Ln = Er(III) and Yb(III), hqH = 8-hydroxyquinoline) have been directly probed with EPR spectroscopy and accurately modeled by spin Hamiltonian techniques. Exploitation of site selectivity via doping experiments in Y(III) and Lu(III) matrices yields simple EPR spectra corresponding to isolated Kramers doublets, allowing determination of the local magnetic properties of the individual sites within the dimetallic compounds. CASSCF-SO calculations and INS and far-IR measurements are all employed to further support the identification and modeling of the local electronic structure for each site. EPR spectra of the pure dimetallic compounds are highly featured and correspond to transitions within the lowest-lying exchange-coupled manifold, permitting determination of the highly anisotropic magnetic exchange between the lanthanide ions. We find a unique orientation for the exchange interaction, corresponding to a common elongated oxygen bridge for both isostructural analogs. This suggests a microscopic physical connection to the magnetic superexchange. These results are of fundamental importance for building and validating model microscopic Hamiltonians to understand the origins of magnetic interactions between lanthanides and how they may be controlled with chemistry.

Confirmation of thalamosubthalamic projections by electron microscopic autoradiography.

PubMed

Sugimoto, T; Hattori, T

1983-05-16

Direct projections from the centre median-parafascicular complex (CM-Pf) to the subthalamic nucleus(STN) were confirmed by electron microscopic autoradiography. [3H]Leucine injections into the rat CM-Pf produced preferential labeling of Gray's type I boutons containing round vesicles in the ipsilateral STN. Further results strongly suggested the existence of some common CM-Pf projections to both the striatum and STN.

Collection and Analysis of Aircraft Emitted Particles

NASA Technical Reports Server (NTRS)

Wilson, James Charles

1999-01-01

The University of Denver Aerosol Group proposed to adapt an impactor system for the collection of particles emitted by aircraft. The collection substrates were electron microscope grids which were analyzed by Dr. Pat Sheridan using a transmission electron microscope. The impactor was flown in the SNIFF behind aircraft and engine emissions were sampled. This report details the results of that work.

Foucault imaging by using non-dedicated transmission electron microscope

DOE Office of Scientific and Technical Information (OSTI.GOV)

Taniguchi, Yoshifumi; Matsumoto, Hiroaki; Harada, Ken

2012-08-27

An electron optical system for observing Foucault images was constructed using a conventional transmission electron microscope without any special equipment for Lorentz microscopy. The objective lens was switched off and an electron beam was converged by a condenser optical system to the crossover on the selected area aperture plane. The selected area aperture was used as an objective aperture to select the deflected beam for Foucault mode, and the successive image-forming lenses were controlled for observation of the specimen images. The irradiation area on the specimen was controlled by selecting the appropriate diameter of the condenser aperture.

Electron microscopic evaluation of a gold glaucoma micro shunt after explantation.

PubMed

Berk, Thomas A; Tam, Diamond Y; Werner, Liliana; Mamalis, Nick; Ahmed, Iqbal Ike K

2015-03-01

We present a case of an explanted gold glaucoma micro shunt (GMS Plus) and the subsequent light and electron microscopic analyses. The shunt was implanted in a patient with medically refractive glaucoma. The intraocular pressure (IOP) was stable at 12 mm Hg 6 months postoperatively but spiked to 26 mm Hg 6 months later; membranous growth was visible on the implant gonioscopically. A second gold micro shunt was placed 2 years after the first. The IOP was 7 mm Hg 1 week postoperatively but increased to 23 mm Hg 3 weeks later; similar membranous growth was visible on this implant. One of the shunts was explanted, and light and scanning electron microscopic analyses revealed encapsulation around the shunt exterior and connective tissue invasion of the microstructure. This represents the first electron microscopic analysis of an explanted gold glaucoma micro shunt and the first unequivocal images of the fibrotic pseudo-capsule traversing its microchannels and fenestrations. Dr. Ahmed is a consultant to and has received research grants from Solx, Inc. No other author has a financial or proprietary interest in any material or method mentioned. Copyright © 2015 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Review of current progress in nanometrology with the helium ion microscope

NASA Astrophysics Data System (ADS)

Postek, Michael T.; Vladár, András; Archie, Charles; Ming, Bin

2011-02-01

Scanning electron microscopy has been employed as an imaging and measurement tool for more than 50 years and it continues as a primary tool in many research and manufacturing facilities across the world. A new challenger to this work is the helium ion microscope (HIM). The HIM is a new imaging and metrology technology. Essentially, substitution of the electron source with a helium ion source yields a tool visually similar in function to the scanning electron microscope, but very different in the fundamental imaging and measurement process. The imaged and measured signal originates differently than in the scanning electron microscope and that fact and its single atom source diameter may be able to push the obtainable resolution lower, provide greater depth-of-field and ultimately improve the metrology. Successful imaging and metrology with this instrument entails understanding and modeling of new ion beam/specimen interaction physics. As a new methodology, HIM is beginning to show promise and the abundance of potentially advantageous applications for nanometrology has yet to be fully exploited. This paper discusses some of the progress made at NIST in collaboration with IBM to understand the science behind this new technology.

Subcellular localization of leptin and leptin receptor in breast cancer detected in an electron microscopic study.

PubMed

Al-Shibli, Saad M; Amjad, Nasser M; Al-Kubaisi, Muna K; Mizan, Shaikh

2017-01-22

Leptin (LEP) and leptin receptor (LEPR) have long been found associated with breast cancer. So far no high-resolution method such as electron microscopy has been used to investigate the subcellular localization of leptin and leptin receptor in breast cancer. We collected cancer and non-cancer breast tissues from 51 women with invasive ductal breast cancer. Leptin and leptin receptor in the tissues were estimated using immunohistochemistry (IHC). LEP and LEPR were localized at subcellular level by immunocytochemistry (ICC) using ultra-fine gold particle conjugated antibody, and visualized with transmission electron microscopy (TEM). IHC showed high presence of LEP and LEPR in 65% and 67% respectively of the breast cancer samples, 100% and 0% respectively of the adipose tissue samples, and no high presence in the non-cancer breast tissue samples. On TEM views both LEP and LEPR were found highly concentrated within the nucleus of the cancer cells, indicating that nucleus is the principal seat of action. However, presence of high concentration of LEP does not necessarily prove its over-expression, as often concluded, because LEP could be internalized from outside by LEPR in the cells. In contrast, LEPR is definitely over-expressed in the ductal breast cancer cells. Therefore, we hypothesize that over-expression of LEPR, rather than that of LEP has a fundamental role in breast carcinogenesis in particular, and probably for LEP-LEPR associated tumors in general. Copyright © 2016 Elsevier Inc. All rights reserved.

Preparation of polymeric Janus particles by directional UV-induced reactions.

PubMed

Liu, Lianying; Ren, Mingwei; Yang, Wantai

2009-09-15

Polymeric Janus particles are obtained by UV-induced selective surface grafting polymerizations and coupling reactions, in virtue of the light-absorption of photoreactive materials such as the immobilized photoinitiator and spread photoinitiator solution on the surfaces exposed to UV light and the sheltering of densely arrayed immovable particles from light. Varying the monomers or macromolecules applied in photografting polymerization or coupling reaction, and choosing diverse polymeric particles of various size, bicolor and amphiphilic Janus particles could be successfully achieved. Observations by fluorescence microscope, scanning electron microscope ,and transmission electron microscope confirmed the asymmetrical morphology of the resultant Janus particles.

Micro axial tomography: A miniaturized, versatile stage device to overcome resolution anisotropy in fluorescence light microscopy

NASA Astrophysics Data System (ADS)

Staier, Florian; Eipel, Heinz; Matula, Petr; Evsikov, Alexei V.; Kozubek, Michal; Cremer, Christoph; Hausmann, Michael

2011-09-01

With the development of novel fluorescence techniques, high resolution light microscopy has become a challenging technique for investigations of the three-dimensional (3D) micro-cosmos in cells and sub-cellular components. So far, all fluorescence microscopes applied for 3D imaging in biosciences show a spatially anisotropic point spread function resulting in an anisotropic optical resolution or point localization precision. To overcome this shortcoming, micro axial tomography was suggested which allows object tilting on the microscopic stage and leads to an improvement in localization precision and spatial resolution. Here, we present a miniaturized device which can be implemented in a motor driven microscope stage. The footprint of this device corresponds to a standard microscope slide. A special glass fiber can manually be adjusted in the object space of the microscope lens. A stepwise fiber rotation can be controlled by a miniaturized stepping motor incorporated into the device. By means of a special mounting device, test particles were fixed onto glass fibers, optically localized with high precision, and automatically rotated to obtain views from different perspective angles under which distances of corresponding pairs of objects were determined. From these angle dependent distance values, the real 3D distance was calculated with a precision in the ten nanometer range (corresponding here to an optical resolution of 10-30 nm) using standard microscopic equipment. As a proof of concept, the spindle apparatus of a mature mouse oocyte was imaged during metaphase II meiotic arrest under different perspectives. Only very few images registered under different rotation angles are sufficient for full 3D reconstruction. The results indicate the principal advantage of the micro axial tomography approach for many microscopic setups therein and also those of improved resolutions as obtained by high precision localization determination.

Nature and evolution of incommensurate charge order in manganites visualized with cryogenic scanning transmission electron microscopy.

PubMed

El Baggari, Ismail; Savitzky, Benjamin H; Admasu, Alemayehu S; Kim, Jaewook; Cheong, Sang-Wook; Hovden, Robert; Kourkoutis, Lena F

2018-02-13

Incommensurate charge order in hole-doped oxides is intertwined with exotic phenomena such as colossal magnetoresistance, high-temperature superconductivity, and electronic nematicity. Here, we map, at atomic resolution, the nature of incommensurate charge-lattice order in a manganite using scanning transmission electron microscopy at room temperature and cryogenic temperature ([Formula: see text]93 K). In diffraction, the ordering wave vector changes upon cooling, a behavior typically associated with incommensurate order. However, using real space measurements, we discover that the ordered state forms lattice-locked regions over a few wavelengths interspersed with phase defects and changing periodicity. The cations undergo picometer-scale ([Formula: see text]6 pm to 11 pm) transverse displacements, suggesting that charge-lattice coupling is strong. We further unearth phase inhomogeneity in the periodic lattice displacements at room temperature, and emergent phase coherence at 93 K. Such local phase variations govern the long-range correlations of the charge-ordered state and locally change the periodicity of the modulations, resulting in wave vector shifts in reciprocal space. These atomically resolved observations underscore the importance of lattice coupling and phase inhomogeneity, and provide a microscopic explanation for putative "incommensurate" order in hole-doped oxides. Copyright © 2018 the Author(s). Published by PNAS.

Interaction of electrons with light metal hydrides in the transmission electron microscope.

PubMed

Wang, Yongming; Wakasugi, Takenobu; Isobe, Shigehito; Hashimoto, Naoyuki; Ohnuki, Somei

2014-12-01

Transmission electron microscope (TEM) observation of light metal hydrides is complicated by the instability of these materials under electron irradiation. In this study, the electron kinetic energy dependences of the interactions of incident electrons with lithium, sodium and magnesium hydrides, as well as the constituting element effect on the interactions, were theoretically discussed, and electron irradiation damage to these hydrides was examined using in situ TEM. The results indicate that high incident electron kinetic energy helps alleviate the irradiation damage resulting from inelastic or elastic scattering of the incident electrons in the TEM. Therefore, observations and characterizations of these materials would benefit from increased, instead decreased, TEM operating voltage. © The Author 2014. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Improvement to the scanning electron microscope image adaptive Canny optimization colorization by pseudo-mapping.

PubMed

Lo, T Y; Sim, K S; Tso, C P; Nia, M E

2014-01-01

An improvement to the previously proposed adaptive Canny optimization technique for scanning electron microscope image colorization is reported. The additional feature, called pseudo-mapping technique, is that the grayscale markings are temporarily mapped to a set of pre-defined pseudo-color map as a mean to instill color information for grayscale colors in chrominance channels. This allows the presence of grayscale markings to be identified; hence optimization colorization of grayscale colors is made possible. This additional feature enhances the flexibility of scanning electron microscope image colorization by providing wider range of possible color enhancement. Furthermore, the nature of this technique also allows users to adjust the luminance intensities of selected region from the original image within certain extent. © 2014 Wiley Periodicals, Inc.

Mechanics of Individual, Isolated Vortices in a Cuprate Superconductor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Auslaender, M.

2010-05-25

Superconductors often contain quantized microscopic whirlpools of electrons, called vortices, that can be modeled as one-dimensional elastic objects. Vortices are a diverse playground for condensed matter because of the interplay between thermal fluctuations, vortex-vortex interactions, and the interaction of the vortex core with the three-dimensional disorder landscape. While vortex matter has been studied extensively, the static and dynamic properties of an individual vortex have not. Here we employ magnetic force microscopy (MFM) to image and manipulate individual vortices in detwinned, single crystal YBa{sub 2}Cu{sub 3}O{sub 6.991} (YBCO), directly measuring the interaction of a moving vortex with the local disorder potential.more » We find an unexpected and dramatic enhancement of the response of a vortex to pulling when we wiggle it transversely. In addition, we find enhanced vortex pinning anisotropy that suggests clustering of oxygen vacancies in our sample and demonstrates the power of MFM to probe vortex structure and microscopic defects that cause pinning.« less

A quantitative and spatially resolved analysis of the performance-bottleneck in high efficiency, planar hybrid perovskite solar cells

DOE PAGES

Draguta, Sergiu; Christians, Jeffrey A.; Morozov, Yurii V.; ...

2018-01-01

Hybrid perovskites represent a potential paradigm shift for the creation of low-cost solar cells. Current power conversion efficiencies (PCEs) exceed 22%. However, despite this, record PCEs are still far from their theoretical Shockley–Queisser limit of 31%. To increase these PCE values, there is a pressing need to understand, quantify and microscopically model charge recombination processes in full working devices. Here, we present a complete microscopic account of charge recombination processes in high efficiency (18–19% PCE) hybrid perovskite (mixed cation and methylammonium lead iodide) solar cells. We employ diffraction-limited optical measurements along with relevant kinetic modeling to establish, for the firstmore » time, local photoluminescence quantum yields, trap densities, trapping efficiencies, charge extraction efficiencies, quasi-Fermi-level splitting, and effective PCE estimates. Correlations between these spatially resolved parameters, in turn, allow us to conclude that intrinsic electron traps in the perovskite active layers limit the performance of these state-of-the-art hybrid perovskite solar cells.« less

A quantitative and spatially resolved analysis of the performance-bottleneck in high efficiency, planar hybrid perovskite solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Draguta, Sergiu; Christians, Jeffrey A.; Morozov, Yurii V.

Hybrid perovskites represent a potential paradigm shift for the creation of low-cost solar cells. Current power conversion efficiencies (PCEs) exceed 22%. However, despite this, record PCEs are still far from their theoretical Shockley–Queisser limit of 31%. To increase these PCE values, there is a pressing need to understand, quantify and microscopically model charge recombination processes in full working devices. Here, we present a complete microscopic account of charge recombination processes in high efficiency (18–19% PCE) hybrid perovskite (mixed cation and methylammonium lead iodide) solar cells. We employ diffraction-limited optical measurements along with relevant kinetic modeling to establish, for the firstmore » time, local photoluminescence quantum yields, trap densities, trapping efficiencies, charge extraction efficiencies, quasi-Fermi-level splitting, and effective PCE estimates. Correlations between these spatially resolved parameters, in turn, allow us to conclude that intrinsic electron traps in the perovskite active layers limit the performance of these state-of-the-art hybrid perovskite solar cells.« less

Public perception of risk and its consequences: the case of a natural fibrous mineral deposit.

PubMed

Major, G; Vardy, G F

1989-01-01

A public authority building a breakwater and other harbour facilities at a small seaport (population 3000) had short-term requirements for 261,000 tonnes of rock and ultimately for 1,000,000 tonnes. A suitable quarry was found about 11 km from the port but unfortunately the rock was found to be contaminated to a small extent with a fibrous mineral identified with the analytical transmission electron microscope as a non-commercial type of fine amphibole with many long fibres. Quarrying only was intended and there were no plans to crush the rock, but the projected work soon brought complaints from local residents, who expressed fears concerning risks to health from what soon became known as 'the asbestos mine'. These complaints posed a dilemma for both the construction and health authorities; they were forcefully expressed, and residents were supported by local newspapers, municipal authorities and regional politicians. The Land and Environment Court ordered (by consent) that the construction authority 'take all reasonable measures to ensure that no loose asbestos material and no rock with any asbestos material exposed on the surface (is) removed from the site'. Personal monitoring of quarry workmen by the membrane filter method and ambient air monitoring near residents' homes with analysis by electron microscope showed that only insignificant concentrations of airborne fibres were present. The breakwater was ultimately completed after much delay and extra expense. Other and greater risks to health and safety, such as the transport of liquid chlorine through the centre of the town to the fish processing plant and the storage, distribution and transport of petroleum products from the nearby regional facilities, were not perceived as such by the residents.

Sakurajima volcano: a physico-chemical study of the health consequences of long-term exposure to volcanic ash

NASA Astrophysics Data System (ADS)

Hillman, S. E.; Horwell, C. J.; Densmore, A. L.; Damby, D. E.; Fubini, B.; Ishimine, Y.; Tomatis, M.

2012-05-01

Regular eruptions from Sakurajima volcano, Japan, repeatedly cover local urban areas with volcanic ash. The frequency of exposure of local populations to the ash led to substantial concerns about possible respiratory health hazards, resulting in many epidemiological and toxicological studies being carried out in the 1980s. However, very few mineralogical data were available for determination of whether the ash was sufficiently fine to present a respiratory hazard. In this study, we review the existing studies and carry out mineralogical, geochemical and toxicological analyses to address whether the ash from Sakurajima has the potential to cause respiratory health problems. The results show that the amount of respirable (<4 μm) material produced by the volcano is highly variable in different eruptions (1.1-18.8 vol.%). The finest samples derive from historical, plinian eruptions but considerable amounts of respirable material were also produced from the most recent vulcanian eruptive phase (since 1955). The amount of cristobalite, a crystalline silica polymorph which has the potential to cause chronic respiratory diseases, is ~3-5 wt.% in the bulk ash. Scanning electron microscope and transmission electron microscope imaging showed no fibrous particles similar to asbestos particles. Surface reactivity tests showed that the ash did not produce significant amounts of highly reactive hydroxyl radicals (0.09-1.35 μmol m-2 at 30 min.) in comparison to other volcanic ash types. A basic toxicology assay to assess the ability of ash to rupture the membrane of red blood cells showed low propensity for haemolysis. The findings suggest that the potential health hazard of the ash is low, but exposure and respiratory conditions should still be monitored given the high frequency and durations of exposure.

Characterization of electrical discharges on Teflon dielectrics used as spacecraft thermal control

NASA Technical Reports Server (NTRS)

Yadlowsky, E. J.; Hazelton, R. C.; Churchill, R. J.

1979-01-01

The dual effects of system degradation and reduced life of synchronous-orbit satellites as a result of differential spacecraft charging underscore the need for a clearer understanding of the prevailing electrical discharge phenomena. In a laboratory simulation, the electrical discharge current, surface voltage, emitted particle fluxes, and photo-emission associated with discharge events on electron beam irradiated silver-backed Teflon samples were measured. Sample surface damage was examined with optical and electron beam microscopes. The results are suggestive of a model in which the entire sample surface is discharged by lateral sub-surface currents flowing from a charge deposition layer through a localized discharge channel to the back surface of the sample. The associated return current pulse appears to have a duration which may be a signature by which different discharge processes may be characterized.

Visualization of Nanoplasmonic Coupling to Molecular Orbital in Light Emission Induced by Tunneling Electrons.

PubMed

Yu, Arthur; Li, Shaowei; Wang, Hui; Chen, Siyu; Wu, Ruqian; Ho, W

2018-05-09

The coupling between localized plasmon and molecular orbital in the light emission from a metallic nanocavity has been directly detected and imaged with sub-0.1 nm resolution. The light emission intensity was enhanced when the energy difference between the tunneling electrons and the lowest unoccupied molecular orbital (LUMO) of an azulene molecule matches the energy of a plasmon mode of the nanocavity defined by the Ag-tip and Ag (110) substrate of a scanning tunneling microscope (STM). The spatially resolved image of the light emission intensity matches the spatial distribution of the LUMO obtained by scanning tunneling spectroscopy (STS) and density functional theory (DFT) calculations. Our results highlight the near-field coupling of a molecular orbital to the radiative decay of a plasmonic excitation in a confined nanoscale junction.

Correlative fractography: combining scanning electron microscopy and light microscopes for qualitative and quantitative analysis of fracture surfaces.

PubMed

Hein, Luis Rogerio de Oliveira; de Oliveira, José Alberto; de Campos, Kamila Amato

2013-04-01

Correlative fractography is a new expression proposed here to describe a new method for the association between scanning electron microscopy (SEM) and light microscopy (LM) for the qualitative and quantitative analysis of fracture surfaces. This article presents a new method involving the fusion of one elevation map obtained by extended depth from focus reconstruction from LM with exactly the same area by SEM and associated techniques, as X-ray mapping. The true topographic information is perfectly associated to local fracture mechanisms with this new technique, presented here as an alternative to stereo-pair reconstruction for the investigation of fractured components. The great advantage of this technique resides in the possibility of combining any imaging methods associated with LM and SEM for the same observed field from fracture surface.

Microscopic localization of sterically stabilized liposomes in colon carcinoma-bearing mice.

PubMed

Huang, S K; Lee, K D; Hong, K; Friend, D S; Papahadjopoulos, D

1992-10-01

Using light and electron microscopy, we investigated the in vivo distribution of liposomes sterically stabilized by specific lipids which prolong their circulation in blood. Tissue distribution of sterically stabilized liposomes composed of distearoyl phosphatidylcholine:cholesterol:monosialoganglioside GM1 (10:5:1)-encapsulated 67Ga-Desferal indicates that more than 30% of liposomes still remain in the blood at 24 h after tail vein injection. Moreover, such liposomes accumulated in tumors (C-26 colon carcinoma cells implanted s.c.), reaching almost the same level of uptake as liver (approximately 20% injected dose/g tissue). The microscopic localization of liposomes labeled with encapsulated colloidal gold or rhodamine-labeled dextran coincided well with the tissue distribution. To evaluate circulation parameters, two sizes of gold-containing egg phosphatidylcholine:cholesterol:distearoyl phosphatidylethanolamine (derivatized at its amino position with a 1900 molecular weight segment of polyethylene glycol) (10:5:0.8) liposomes were injected. The plasma was examined by electron microscopy of negative-stained preparations at 0.5, 4, and 24 h after liposome injection. It was found that the ratio of small (less than 100 nm diameter) to large (greater than 100 nm) liposomes increased with time, indicating a much faster clearance of the larger liposomes. To detect the localization of liposomes in various tissues, appropriate samples were fixed 24 h after the injection of gold-containing liposomes (between 80 and 100 nm in diameter) composed of egg phosphatidylcholine:cholesterol:monosialoganglioside GM1 (10:5:1) or egg phosphatidylcholine:cholesterol:derivatized distearoyl phosphatidylethanolamine. The tissues examined for this study included normal liver, bone marrow, and implanted neoplasms. Silver-enhanced colloidal gold was found predominantly within Kupffer cells in the normal liver and within macrophages in the bone marrow. Rarely were any silver-enhanced gold particles detected in hepatocytes. In all preparations, electron microscopy revealed the presence of gold in endosomes and lysosomes of fixed sinusoidal lining macrophages in the liver and bone marrow. Peripheral to the implanted tumors, silver enhancement revealed gold in small blood vessels and focally beyond the vessel boundaries in extracellular spaces around tumor cells. Gold particles were not observed within the tumor cell cytoplasm. At the tumor border, nonenhanced gold was occasionally seen by electron microscopy in cells of the mononuclear phagocyte system. We obtained the same localization pattern as with silver enhancement by using an alternative aqueous content marker, rhodamine B isothiocyanate-dextran. We conclude that liposomes of specific composition, which have the ability to remain in circulation with a half-life of 12-24 h, are also able to transverse the endothelium of small blood vessels, including those in tumors, and extravasate into extracellular spaces.(ABSTRACT TRUNCATED AT 400 WORDS)

Light and electron microscopic immunocytochemical localization of two major proteins in garlic bulb.

PubMed

Wen, G Y; Mato, A; Wisniewski, H M; Malik, M N; Jenkins, E C; Sheikh, A M; Kim, K S

1995-08-01

Garlic is known as a potent spice and a medicine with broad therapeutic properties ranging from antibacterial to anticancer, antidiabetic, and anticoagulant. Two major proteins of 40 KD and 14 KD constituting approximately 96% of total garlic proteins have been recently purified at our Institute. This immunocytochemical and ultrastructural study revealed that the 40 KD protein was localized in the parenchyma sheath cells (PSC) of garlic bulbs, whereas the 14 KD protein was present in the cortical cells (CC). Immunogold electron microscopy study indicated that the 40 KD protein was specifically localized in the globular granules of the cytoplasmic area of PSC. Each globular granule was amorphous and homogenous with membrane limiting its outermost layer. The yellowish color of PSC in freshly cut slices of garlic bulb suggested that PSC may have sulfur-containing compounds such as allicin, the primary contributor of the pungency and medicinal properties of garlic. Ellman's reagent test quantitatively revealed that there were 17.8 n moles sulfhydryl (SH)/ml of 40 KD garlic protein. Microtubule tubulin in mitotic figures from PHA-stimulated human short-term whole blood cultures reacted strongly with antitubulin antibody but reacted negatively with anti-40 KD garlic protein antibodies and therefore was not related to the 40 KD garlic protein immunocytochemically.

Combination of external-beam radiotherapy with intraoperative electron-beam therapy is effective in incompletely resected pediatric malignancies.

PubMed

Oertel, Susanne; Niethammer, Andreas G; Krempien, Robert; Roeder, Falk; Eble, Michael J; Baer, Claudia; Huber, Peter E; Kulozik, Andreas; Waag, Karl-Ludwig; Treiber, Martina; Debus, Juergen

2006-01-01

Intraoperative electron-beam radiotherapy (IOERT) has been applied for local dose escalation in over 1,400 patients in Heidelberg since 1991. Among these were 30 children, in 18 of whom IOERT was employed in radiation treatment with external-beam radiotherapy (EBRT) on account of incomplete resection. We address the question whether IOERT is able to compensate for microscopic or macroscopic tumor residue if employed in the overall radiation regimen. The data of the aforementioned 18 children were analyzed with regard to local recurrence, overall survival, and complication rates. All children suffered from either sarcomas or neuroblastomas. In all children, IOERT was employed for local dose escalation after or before EBRT. After a median follow-up of 60.5 months, 15 of the treated children are alive. One local failure has been observed. Six children show clinically significant late morbidity, including the loss of a treated limb (Radiation Therapy Oncology Group Grade 4 [RTOG 4]), a severe nerve lesion (RTOG 3), an orthopedic complication (RTOG 2), a ureteral stenosis (not clinically significant), and a kidney hypotrophy (not clinically significant). In 1 child a fracture due to radionecrosis (RTOG 4) was diagnosed; however, in the follow-up, local tumor relapse was diagnosed as another possible reason for the fracture. Regarding the low incidence of local failure, IOERT seems to be able to compensate incomplete tumor resection in childhood sarcoma and neuroblastoma patients. The incidence of late morbidity is low enough to justify the employment of IOERT as part of the radiation treatment regimen for pediatric patients.

Simulation of transmission electron microscope images of biological specimens.

PubMed

Rullgård, H; Ofverstedt, L-G; Masich, S; Daneholt, B; Oktem, O

2011-09-01

We present a new approach to simulate electron cryo-microscope images of biological specimens. The framework for simulation consists of two parts; the first is a phantom generator that generates a model of a specimen suitable for simulation, the second is a transmission electron microscope simulator. The phantom generator calculates the scattering potential of an atomic structure in aqueous buffer and allows the user to define the distribution of molecules in the simulated image. The simulator includes a well defined electron-specimen interaction model based on the scalar Schrödinger equation, the contrast transfer function for optics, and a noise model that includes shot noise as well as detector noise including detector blurring. To enable optimal performance, the simulation framework also includes a calibration protocol for setting simulation parameters. To test the accuracy of the new framework for simulation, we compare simulated images to experimental images recorded of the Tobacco Mosaic Virus (TMV) in vitreous ice. The simulated and experimental images show good agreement with respect to contrast variations depending on dose and defocus. Furthermore, random fluctuations present in experimental and simulated images exhibit similar statistical properties. The simulator has been designed to provide a platform for development of new instrumentation and image processing procedures in single particle electron microscopy, two-dimensional crystallography and electron tomography with well documented protocols and an open source code into which new improvements and extensions are easily incorporated. © 2011 The Authors Journal of Microscopy © 2011 Royal Microscopical Society.

Revealing the 1 nm/s extensibility of nanoscale amorphous carbon in a scanning electron microscope.

PubMed

Zhang, Wei

2013-01-01

In an ultra-high vacuum scanning electron microscope, the edged branches of amorphous carbon film (∼10 nm thickness) can be continuously extended with an eye-identifying speed (on the order of ∼1 nm/s) under electron beam. Such unusual mobility of amorphous carbon may be associated with deformation promoted by the electric field, which resulted from an inner secondary electron potential difference from the main trunk of carbon film to the tip end of branches under electron beam. This result demonstrates importance of applying electrical effects to modify properties of carbon materials. It may have positive implications to explore some amorphous carbon as electron field emission device. © Wiley Periodicals, Inc.

THE IN VITRO DIFFERENTIATION OF MONONUCLEAR PHAGOCYTES

PubMed Central

Cohn, Zanvil A.; Fedorko, Martha E.; Hirsch, James G.

1966-01-01

A combined morphological, autoradiographic, and cytochemical study at the electron microscope level has been directed towards the formation of electron-opaque granules of cultured macrophages. Labeling of the membrane-bound vesicular structures of pinocytic origin was accomplished with colloidal gold. The initial uptake of gold occurred within micropinocytic vesicles. These electron-lucent vesicles subsequently fused with and discharged their contents into larger pinocytic vacuoles. Colloidal gold was homogeneously distributed in the large pinosomes. In contrast, gold was initially deposited in the periphery of preformed dense granules indicating that these structures were also in constant interaction with the external environment. Colloidal gold was not observed within the cisternae of the endoplasmic reticulum nor within the saccules or vesicles of the Golgi apparatus. There were, however, many small, gold-free vesicles, indistinguishable from Golgi vesicles, which were preferentially aligned about and appeared to fuse with the large pinosomes. The intracellular flow of leucine-H3-labeled protein was followed by electron microscopic autoradiography. After a 15 min pulse of labeled amino acid there was initial labeling of the rough endoplasmic reticulum. Subsequently, much of the label appeared in the Golgi complex. At still later time periods the cytoplasmic dense granules contained the majority of the isotope. Acid phosphatase activity was localized to the dense granules and in the majority of cells to the Golgi apparatus. It is suggested that hydrolytic enzymes are initially synthesized in the endoplasmic reticulum and are then transferred to the Golgi apparatus. Here they are packaged into small Golgi vesicles which represent the primary lysosome of macrophages. The Golgi vesicles subsequently fuse with pinosomes, thereby discharging their hydrolases and forming digestive granules or secondary lysosomes. PMID:5931922

Low-voltage electron microscopy of polymer and organic molecular thin films.

PubMed

Drummy, Lawrence F; Yang, Junyan; Martin, David C

2004-06-01

We have demonstrated the capabilities of a novel low-voltage electron microscope (LVEM) for imaging polymer and organic molecular thin films. The LVEM can operate in transmission electron microscopy, scanning transmission electron microscopy, scanning electron microscopy, and electron diffraction modes. The microscope operates at a nominal accelerating voltage of 5 kV and fits on a tabletop. A detailed discussion of the electron-sample interaction processes is presented, and the mean free path for total electron scattering was calculated to be 15 nm for organic samples at 5 kV. The total end point dose for the destruction of crystallinity at 5 kV was estimated at 5 x 10(-4) and 3.5 x 10(-2) C/cm2 for polyethylene and pentacene, respectively. These values are significantly lower than those measured at voltages greater than 100 kV. A defocus series of colloidal gold particles allowed us to estimate the experimental contrast transfer function of the microscope. Images taken of several organic materials have shown high contrast for low atomic number elements and a resolution of 2.5 nm. The materials studied here include thin films of the organic semiconductor pentacene, triblock copolymer films, single-molecule dendrimers, electrospun polymer fibers and gold nanoparticles. Copyright 2004 Elsevier B.V.

[THE CHARACTERISTICS OF MORPHOLOGY OF BIOFILM OF PERIODONTIUM UNDER INFLAMMATORY DISEASES OF GUMS (CHRONIC CATARRHAL GINGIVITIS, CHRONIC PERIODONTITIS, CANDIDA-ASSOCIATED PERIODONTITIS) ACCORDING RESULTS OF ELECTRONIC MICROSCOPY].

PubMed

Ippolitov, E V; Didenko, L V; Tzarev, V N

2015-12-01

The study was carried out to analyze morphology of biofilm of periodontium and to develop electronic microscopic criteria of differentiated diagnostic of inflammatory diseases of gums. The scanning electronic microscopy was applied to analyze samples of bioflm of periodont from 70 patients. Including ten patients with every nosologic form of groups with chronic catarrhal periodontitis. of light, mean and severe degree, chronic catarrhal gingivitis, Candida-associated paroperiodontitis and 20 healthy persons with intact periodontium. The analysis was implemented using dual-beam scanning electronic microscope Quanta 200 3D (FEI company, USA) and walk-through electronic micJEM 100B (JEOL, Japan). To detect marker DNA of periodont pathogenic bacteria in analyzed samples the kit of reagentsfor polymerase chain reaction "MultiDent-5" ("GenLab", Russia). The scanning electronic microscopy in combination with transmission electronic microscopy and polymerase chain reaction permits analyzing structure, composition and degree of development of biofilm of periodontium and to apply differentiated diagnostic of different nosologic forms of inflammatory diseases of periodontium, including light form of chronic periodontitis and gingivitis. The electronic microscopical indications of diseases ofperiodontium of inflammatory character are established: catarrhal gingivitis, (coccal morphological alternate), chronic periodontitis (bacillary morphological alternate), Candida-associated periodontitis (Candida morphological alternate of biofilm ofperiodontium).

Acquisition parameters optimization of a transmission electron forward scatter diffraction system in a cold-field emission scanning electron microscope for nanomaterials characterization.

PubMed

Brodusch, Nicolas; Demers, Hendrix; Trudeau, Michel; Gauvin, Raynald

2013-01-01

Transmission electron forward scatter diffraction (t-EFSD) is a new technique providing crystallographic information with high resolution on thin specimens by using a conventional electron backscatter diffraction (EBSD) system in a scanning electron microscope. In this study, the impact of tilt angle, working distance, and detector distance on the Kikuchi pattern quality were investigated in a cold-field emission scanning electron microscope (CFE-SEM). We demonstrated that t-EFSD is applicable for tilt angles ranging from -20° to -40°. Working distance (WD) should be optimized for each material by choosing the WD for which the EBSD camera screen illumination is the highest, as the number of detected electrons on the screen is directly dependent on the scattering angle. To take advantage of the best performances of the CFE-SEM, the EBSD camera should be close to the sample and oriented towards the bottom to increase forward scattered electron collection efficiency. However, specimen chamber cluttering and beam/mechanical drift are important limitations in the CFE-SEM used in this work. Finally, the importance of t-EFSD in materials science characterization was illustrated through three examples of phase identification and orientation mapping. © Wiley Periodicals, Inc.

Direction-division multiplexed holographic free-electron-driven light sources

NASA Astrophysics Data System (ADS)

Clarke, Brendan P.; MacDonald, Kevin F.; Zheludev, Nikolay I.

2018-01-01

We report on a free-electron-driven light source with a controllable direction of emission. The source comprises a microscopic array of plasmonic surface-relief holographic domains, each tailored to direct electron-induced light emission at a selected wavelength into a collimated beam in a prescribed direction. The direction-division multiplexed source is tested by driving it with the 30 kV electron beam of a scanning electron microscope: light emission, at a wavelength of 800 nm in the present case, is switched among different output angles by micron-scale repositioning of the electron injection point among domains. Such sources, with directional switching/tuning possible at picosecond timescales, may be applied to field-emission and surface-conduction electron-emission display technologies, optical multiplexing, and charged-particle-beam position metrology.

Development of a high brightness ultrafast Transmission Electron Microscope based on a laser-driven cold field emission source.

PubMed

Houdellier, F; Caruso, G M; Weber, S; Kociak, M; Arbouet, A

2018-03-01

We report on the development of an ultrafast Transmission Electron Microscope based on a cold field emission source which can operate in either DC or ultrafast mode. Electron emission from a tungsten nanotip is triggered by femtosecond laser pulses which are tightly focused by optical components integrated inside a cold field emission source close to the cathode. The properties of the electron probe (brightness, angular current density, stability) are quantitatively determined. The measured brightness is the largest reported so far for UTEMs. Examples of imaging, diffraction and spectroscopy using ultrashort electron pulses are given. Finally, the potential of this instrument is illustrated by performing electron holography in the off-axis configuration using ultrashort electron pulses. Copyright © 2017 Elsevier B.V. All rights reserved.

Rapid Neurofibrillary Tangle Formation after Localized Gene Transfer of Mutated Tau

PubMed Central

Klein, Ronald L.; Lin, Wen-Lang; Dickson, Dennis W.; Lewis, Jada; Hutton, Michael; Duff, Karen; Meyer, Edwin M.; King, Michael A.

2004-01-01

Neurofibrillary pathology was produced in the brains of adult rats after localized gene transfer of human tau carrying the P301L mutation, which is associated with frontotemporal dementia with parkinsonism. Within 1 month of in situ transfection of the basal forebrain region of normal rats, tau-immunoreactive and argyrophilic neuronal lesions formed. The fibrillar lesions had features of neurofibrillary tangles and tau immunoreactivity at light and electron microscopic levels. In addition to neurofibrillary tangles, other tau pathology, including pretangles and neuropil threads, was abundant and widespread. Tau gene transfer to the hippocampal region of amyloid-depositing transgenic mice produced pretangles and threads, as well as intensely tau-immunoreactive neurites in amyloid plaques. The ability to produce neurofibrillary pathology in adult rodents makes this a useful method to study tau-related neurodegeneration. PMID:14695347

Solid-state nanopores of controlled geometry fabricated in a transmission electron microscope

NASA Astrophysics Data System (ADS)

Qian, Hui; Egerton, Ray F.

2017-11-01

Energy-filtered transmission electron microscopy and electron tomography were applied to in situ studies of the formation, shape, and diameter of nanopores formed in a silicon nitride membrane in a transmission electron microscope. The nanopore geometry was observed in three dimensions by electron tomography. Drilling conditions, such as probe current, beam convergence angle, and probe position, affect the formation rate and the geometry of the pores. With a beam convergence semi-angle of α = 22 mrad, a conical shaped nanopore is formed but at α = 45 mrad, double-cone (hourglass-shaped) nanopores were produced. Nanopores with an effective diameter between 10 nm and 1.8 nm were fabricated by controlling the drilling time.

Note: Electron energy spectroscopy mapping of surface with scanning tunneling microscope.

PubMed

Li, Meng; Xu, Chunkai; Zhang, Panke; Li, Zhean; Chen, Xiangjun

2016-08-01

We report a novel scanning probe electron energy spectrometer (SPEES) which combines a double toroidal analyzer with a scanning tunneling microscope to achieve both topography imaging and electron energy spectroscopy mapping of surface in situ. The spatial resolution of spectroscopy mapping is determined to be better than 0.7 ± 0.2 μm at a tip sample distance of 7 μm. Meanwhile, the size of the field emission electron beam spot on the surface is also measured, and is about 3.6 ± 0.8 μm in diameter. This unambiguously demonstrates that the spatial resolution of SPEES technique can be much better than the size of the incident electron beam.

Low cost, high performance processing of single particle cryo-electron microscopy data in the cloud

PubMed Central

Cianfrocco, Michael A; Leschziner, Andres E

2015-01-01

The advent of a new generation of electron microscopes and direct electron detectors has realized the potential of single particle cryo-electron microscopy (cryo-EM) as a technique to generate high-resolution structures. Calculating these structures requires high performance computing clusters, a resource that may be limiting to many likely cryo-EM users. To address this limitation and facilitate the spread of cryo-EM, we developed a publicly available ‘off-the-shelf’ computing environment on Amazon's elastic cloud computing infrastructure. This environment provides users with single particle cryo-EM software packages and the ability to create computing clusters with 16–480+ CPUs. We tested our computing environment using a publicly available 80S yeast ribosome dataset and estimate that laboratories could determine high-resolution cryo-EM structures for $50 to $1500 per structure within a timeframe comparable to local clusters. Our analysis shows that Amazon's cloud computing environment may offer a viable computing environment for cryo-EM. DOI: http://dx.doi.org/10.7554/eLife.06664.001 PMID:25955969

Real-space localization and quantification of hole distribution in chain-ladder Sr3Ca11Cu24O41 superconductor.

PubMed

Bugnet, Matthieu; Löffler, Stefan; Hawthorn, David; Dabkowska, Hanna A; Luke, Graeme M; Schattschneider, Peter; Sawatzky, George A; Radtke, Guillaume; Botton, Gianluigi A

2016-03-01

Understanding the physical properties of the chain-ladder Sr3Ca11Cu24O41 hole-doped superconductor has been precluded by the unknown hole distribution among chains and ladders. We use electron energy-loss spectrometry (EELS) in a scanning transmission electron microscope (STEM) at atomic resolution to directly separate the contributions of chains and ladders and to unravel the hole distribution from the atomic scale variations of the O-K near-edge structures. The experimental data unambiguously demonstrate that most of the holes lie within the chain layers. A quantitative interpretation supported by inelastic scattering calculations shows that about two holes are located in the ladders, and about four holes in the chains, shedding light on the electronic structure of Sr3Ca11Cu24O41. Combined atomic resolution STEM-EELS and inelastic scattering calculations is demonstrated as a powerful approach toward a quantitative understanding of the electronic structure of cuprate superconductors, offering new possibilities for elucidating their physical properties.

Z-scan studies of the nonlinear optical properties of gold nanoparticles prepared by electron beam deposition.

PubMed

Mezher, M H; Nady, A; Penny, R; Chong, W Y; Zakaria, R

2015-11-20

This paper details the fabrication process for placing single-layer gold (Au) nanoparticles on a planar substrate, and investigation of the resulting optical properties that can be exploited for nonlinear optics applications. Preparation of Au nanoparticles on the substrate involved electron beam deposition and subsequent thermal dewetting. The obtained thin films of Au had a variation in thicknesses related to the controllable deposition time during the electron beam deposition process. These samples were then subjected to thermal annealing at 600°C to produce a randomly distributed layer of Au nanoparticles. Observation from field-effect scanning electron microscope (FESEM) images indicated the size of Au nanoparticles ranges from ∼13 to ∼48  nm. Details of the optical properties related to peak absorption of localized surface plasmon resonance (LSPR) of the nanoparticle were revealed by use of UV-Vis spectroscopy. The Z-scan technique was used to measure the nonlinear effects on the fabricated Au nanoparticle layers where it strongly relates LSPR and nonlinear optical properties.

Real-space localization and quantification of hole distribution in chain-ladder Sr3Ca11Cu24O41 superconductor

PubMed Central

Bugnet, Matthieu; Löffler, Stefan; Hawthorn, David; Dabkowska, Hanna A.; Luke, Graeme M.; Schattschneider, Peter; Sawatzky, George A.; Radtke, Guillaume; Botton, Gianluigi A.

2016-01-01

Understanding the physical properties of the chain-ladder Sr3Ca11Cu24O41 hole-doped superconductor has been precluded by the unknown hole distribution among chains and ladders. We use electron energy-loss spectrometry (EELS) in a scanning transmission electron microscope (STEM) at atomic resolution to directly separate the contributions of chains and ladders and to unravel the hole distribution from the atomic scale variations of the O-K near-edge structures. The experimental data unambiguously demonstrate that most of the holes lie within the chain layers. A quantitative interpretation supported by inelastic scattering calculations shows that about two holes are located in the ladders, and about four holes in the chains, shedding light on the electronic structure of Sr3Ca11Cu24O41. Combined atomic resolution STEM-EELS and inelastic scattering calculations is demonstrated as a powerful approach toward a quantitative understanding of the electronic structure of cuprate superconductors, offering new possibilities for elucidating their physical properties. PMID:27051872

Flexible non-diffractive vortex microscope for three-dimensional depth-enhanced super-localization of dielectric, metal and fluorescent nanoparticles

NASA Astrophysics Data System (ADS)

Bouchal, Petr; Bouchal, Zdeněk

2017-10-01

In the past decade, probe-based super-resolution using temporally resolved localization of emitters became a groundbreaking imaging strategy in fluorescence microscopy. Here we demonstrate a non-diffractive vortex microscope (NVM), enabling three-dimensional super-resolution fluorescence imaging and localization and tracking of metal and dielectric nanoparticles. The NVM benefits from vortex non-diffractive beams (NBs) creating a double-helix point spread function that rotates under defocusing while maintaining its size and shape unchanged. Using intrinsic properties of the NBs, the dark-field localization of weakly scattering objects is achieved in a large axial range exceeding the depth of field of the microscope objective up to 23 times. The NVM was developed using an upright microscope Nikon Eclipse E600 operating with a spiral lithographic mask optimized using Fisher information and built into an add-on imaging module or microscope objective. In evaluation of the axial localization accuracy the root mean square error below 18 nm and 280 nm was verified over depth ranges of 3.5 μm and 13.6 μm, respectively. Subwavelength gold and polystyrene beads were localized with isotropic precision below 10 nm in the axial range of 3.5 μm and the axial precision reduced to 30 nm in the extended range of 13.6 μm. In the fluorescence imaging, the localization with isotropic precision below 15 nm was demonstrated in the range of 2.5 μm, whereas in the range of 8.3 μm, the precision of 15 nm laterally and 30-50 nm axially was achieved. The tracking of nanoparticles undergoing Brownian motion was demonstrated in the volume of 14 × 10 × 16 μm3. Applicability of the NVM was tested by fluorescence imaging of LW13K2 cells and localization of cellular proteins.

Micro-buffy coats of whole blood: a method for the electron microscopic study of mononuclear cells.

PubMed

Nunes, J F; Soares, J O; Alves de Matos, A P

1979-09-01

A method for the electron microscopic study of human peripheral lymphocytes by which very small buffy coats are obtained through centrifugation of heparinized whole blood in glass or plastic microhematocrit tubes is presented. This method is time saving and efficient, yielding well preserved material and a comparatively large number of mononuclear cells (mainly lymphocytes) in each thin section.

Practical application of HgI2 detectors to a space-flight scanning electron microscope

NASA Technical Reports Server (NTRS)

Bradley, J. G.; Conley, J. M.; Albee, A. L.; Iwanczyk, J. S.; Dabrowski, A. J.

1989-01-01

Mercuric iodide X-ray detectors have been undergoing tests in a prototype scanning electron microscope system being developed for unmanned space flight. The detector program addresses the issues of geometric configuration in the SEM, compact packaging that includes separate thermoelectric coolers for the detector and FET, X-ray transparent hermetic encapsulation and electrical contacts, and a clean vacuum environment.

Effect of process parameters on microstructure and mechanical properties of friction stir welded joints: A review

NASA Astrophysics Data System (ADS)

Wanare, S. P.; Kalyankar, V. D.

2018-04-01

Friction stir welding is emerging as a promising technique for joining of lighter metal alloys due to its several advantages over conventional fusion welding processes such as low thermal distortion, good mechanical properties, fine weld joint microstructure, etc. This review article mainly focuses on analysis of microstructure and mechanical properties of friction stir welded joints. Various microstructure characterization techniques used by previous researchers such as optical microscopes, x-ray diffraction, electron probe microscope, transmission electron microscope, scanning electron microscopes with electron back scattered diffraction, electron dispersive microscopy, etc. are thoroughly overviewed and their results are discussed. The effects of friction stir welding process parameters such as tool rotational speed, welding speed, tool plunge depth, axial force, tool shoulder diameter to tool pin diameter ratio, tool geometry etc. on microstructure and mechanical properties of welded joints are studied and critical observations are noted down. The microstructure examination carried out by previous researchers on various zones of welded joints such as weld zone, heat affected zone and base metal are studied and critical remarks have been presented. Mechanical performances of friction stir welded joints based on tensile test, micro-hardness test, etc. are discussed. This article includes exhaustive literature review of standard research articles which may become ready information for subsequent researchers to establish their line of action.

Visualization of Neutrophil Extracellular Traps and Fibrin Meshwork in Human Fibrinopurulent Inflammatory Lesions: III. Correlative Light and Electron Microscopic Study

PubMed Central

Onouchi, Takanori; Shiogama, Kazuya; Mizutani, Yasuyoshi; Takaki, Takashi; Tsutsumi, Yutaka

2016-01-01

Neutrophil extracellular traps (NETs) released from dead neutrophils at the site of inflammation represent webs of neutrophilic DNA stretches dotted with granule-derived antimicrobial proteins, including lactoferrin, and play important roles in innate immunity against microbial infection. We have shown the coexistence of NETs and fibrin meshwork in varied fibrinopurulent inflammatory lesions at both light and electron microscopic levels. In the present study, correlative light and electron microscopy (CLEM) employing confocal laser scanning microscopy and scanning electron microscopy was performed to bridge light and electron microscopic images of NETs and fibrin fibrils in formalin-fixed, paraffin-embedded, autopsied lung sections of legionnaire’s pneumonia. Lactoferrin immunoreactivity and 4'-6-diamidino-2-phenylindole (DAPI) reactivity were used as markers of NETs, and fibrin was probed by fibrinogen gamma chain. Of note is that NETs light microscopically represented as lactoferrin and DAPI-colocalized dots, 2.5 μm in diameter. CLEM gave super-resolution images of NETs and fibrin fibrils: “Dotted” NETs were ultrastructurally composed of fine filaments and masses of 58 nm-sized globular materials. A fibrin fibril consisted of clusters of smooth-surfaced filaments. NETs filaments (26 nm in diameter) were significantly thinner than fibrin filaments (295 nm in diameter). Of note is that CLEM was applicable to formalin-fixed, paraffin-embedded sections of autopsy material. PMID:27917008

Iridates and RuCl3 - from Heisenberg antiferromagnets to potential Kitaev spin-liquids

NASA Astrophysics Data System (ADS)

van den Brink, Jeroen

The observed richness of topological states on the single-electron level prompts the question what kind of topological phases can develop in more strongly correlated, many-body electron systems. Correlation effects, in particular intra- and inter-orbital electron-electron interactions, are very substantial in 3 d transition-metal compounds such as the copper oxides, but the spin-orbit coupling (SOC) is weak. In 5 d transition-metal compounds such as iridates, the interesting situation arises that the SOC and Coulomb interactions meet on the same energy scale. The electronic structure of iridates thus depends on a strong competition between the electronic hopping amplitudes, local energy-level splittings, electron-electron interaction strengths, and the SOC of the Ir 5d electrons. The interplay of these ingredients offers the potential to stabilise relatively well-understood states such as a 2D Heisenberg-like antiferromagnet in Sr2IrO4, but in principle also far more exotic ones, such a topological Kitaev quantum spin liquid, in (hyper)honeycomb iridates. I will discuss the microscopic electronic structures of these iridates, their proximity to idealized Heisenberg and Kitaev models and our contributions to establishing the physical factors that appear to have preempted the realization of quantum spin liquid phases so far and include a discussion on the 4d transition metal chloride RuCl3. Supported by SFB 1143 of the Deutsche Forschungsgemeinschaft.

Disentangling specific versus generic doping mechanisms in oxide heterointerfaces

NASA Astrophysics Data System (ADS)

Gabel, J.; Zapf, M.; Scheiderer, P.; Schütz, P.; Dudy, L.; Stübinger, M.; Schlueter, C.; Lee, T.-L.; Sing, M.; Claessen, R.

2017-05-01

More than a decade after the discovery of the two-dimensional electron system (2DES) at the interface between the band insulators LaAlO3 (LAO) and SrTiO3 (STO) its microscopic origin is still under debate. Several explanations have been proposed, the main contenders being electron doping by oxygen vacancies and electronic reconstruction, i.e., the redistribution of electrons to the interface to minimize the electrostatic energy in the polar LAO film. However, no experiment thus far could provide unambiguous information on the microscopic origin of the interfacial charge carriers. Here we utilize a novel experimental approach combining photoelectron spectroscopy (PES) with highly brilliant synchrotron radiation and apply it to a set of samples with varying key parameters that are thought to be crucial for the emergence of interfacial conductivity. Based on microscopic insight into the electronic structure, we obtain results tipping the scales in favor of polar discontinuity as a generic, robust driving force for the 2DES formation. Likewise, other functionalities such as magnetism or superconductivity might be switched in all-oxide devices by polarity-driven charge transfer.

Fine structure of the dorsal lingual epithelium of the juvenile hawksbill turtle, Eretmochelys imbricata bissa.

PubMed

Iwasaki, S; Asami, T; Wanichanon, C

1996-04-01

Various species of turtles are adapted to different environments, such as freshwater, seawater, and terrestrial habitats. Comparisons of histological and ultrastructural features of the tongue of the juvenile Hawksbill turtle, Eretmochelys imbricata bissa, with those of freshwater turtles should reveal some aspects of the relationship between the structure of the lingual epithelium and the environment. The light microscope, scanning electron microscope and transmission electron microscope were used. Light microscopy revealed that the mucosal epithelium of the tongue was of the keratinized, stratified squamous type. Under the scanning electron microscope, no lingual papillae were visible on the dorsal surface of the tongue. Micropits and the thickening of cell margins were clearly seen on the surface of cells located on the outermost side. The transmission electron microscope revealed that the cells in the intermediate layer were gradually flattened from the basal side to the surface side, as were their nuclei. In the shallow intermediate layer, the cells were significantly flattened, and their nuclei were condensed or had disappeared. The cytoplasm contained keratohyalin granules, tonofibrils, free ribosomes, mitochondria, and rough endoplasmic reticulum. Numerous free ribosomes were attached to the surface of small keratohyalin granules. The cells of the keratinized layer were significantly flattened, and their nuclei had completely disappeared. Most of cytoplasm was filled with keratin fibers of high electron density. Keratin fibers of the shedding cells, which were located on the outermost side of the keratinized layer, appeared looser, and each fiber, which was somewhat thicker than the tonofibrils and tonofilaments, was clearly distinguishable. The lingual epithelium of the juvenile Hawksbill turtle differs significantly from that of the adult freshwater turtle, in spite of the similarity in gross morphology of the tongues of these species.

Terrestrial Clay under Microscope

NASA Image and Video Library

2008-09-30

A scanning electron microscope captured this image of terresterial soil containing a phyllosilicate mineral from Koua Bocca, Ivory Coast, West Africa. This soil shares some similarities with Martian soil scooped by NASA Phoenix Lander.