WorldWideScience

Sample records for atom hrtem insights

  1. HRTEM imaging of atoms at sub-Angstroem resolution

    International Nuclear Information System (INIS)

    O'Keefe, Michael A.; Allard, Lawrence F.; Blom, Douglas A.

    2005-01-01

    John Cowley and his group at Arizona State University pioneered the use of transmission electron microscopy for high-resolution imaging. Images were achieved three decades ago showing the crystal unit cell content at better than 4 A resolution. This achievement enabled researchers to pinpoint the positions of heavy atom columns within the unit cell. Lighter atoms appear as resolution is improved to sub-Angstroem levels. Currently, advanced microscopes can image the columns of the light atoms (carbon, oxygen, nitrogen) that are present in many complex structures, and even the lithium atoms present in some battery materials. Sub-Angstroem imaging, initially achieved by focal-series reconstruction of the specimen exit surface wave, will become commonplace for next-generation electron microscopes with C s -corrected lenses and monochromated electron beams. Resolution can be quantified in terms of peak separation and inter-peak minimum, but the limits imposed on the attainable resolution by the properties of the microscope specimen need to be considered. At extreme resolution the 'size' of atoms can mean that they will not be resolved even when spaced farther apart than the resolution of the microscope. (author)

  2. HRTEM Imaging of Atoms at Sub-Angstrom Resolution

    Energy Technology Data Exchange (ETDEWEB)

    O' Keefe, Michael A.; Allard, Lawrence F.; Blom, Douglas A.

    2005-04-06

    John Cowley and his group at Arizona State University pioneered the use of transmission electron microscopy (TEM) for high-resolution imaging. Images were achieved three decades ago showing the crystal unit cell content at better than 4 Angstrom resolution. This achievement enabled researchers to pinpoint the positions of heavy atom columns within the unit cell. Lighter atoms appear as resolution is improved to sub-Angstrom levels. Currently, advanced microscopes can image the columns of the light atoms (carbon, oxygen, nitrogen) that are present in many complex structures, and even the lithium atoms present in some battery materials. Sub-Angstrom imaging, initially achieved by focal-series reconstruction of the specimen exit surface wave, will become common place for next-generation electron microscopes with CS-corrected lenses and monochromated electron beams. Resolution can be quantified in terms of peak separation and inter-peak minimum, but the limits imposed on the attainable resolution by the properties of the micro-scope specimen need to be considered. At extreme resolution the ''size'' of atoms can mean that they will not be resolved even when spaced farther apart than the resolution of the microscope.

  3. Chemical inhomogeneity in In{sub x}Ga{sub 1-x}N and ZnO. A HRTEM study on atomic scale clustering

    Energy Technology Data Exchange (ETDEWEB)

    Bartel, T.P.

    2008-10-08

    Nanostructuration as well as the nucleation and growth of nanoparticles pervades the development of modern materials and devices. Quantitative high resolution transmission electron microscopy (HRTEM) is currently being developed for a structural and chemical analysis at an atomic scale. It is used in this thesis to study the chemical inhomogeneity and clustering in In{sub x}Ga{sub 1-x}N, InN and ZnO. A methodology for reliable quantitative HRTEM is rst de ned: it necessitates a damage free sample, the avoidance of electron beam damage and the control of microscope instabilities. With these conditions satis ed, the reliability of quantitative HRTEM is demonstrated by an accurate measurement of lattice relaxation in a thin TEM sample. Clustering in an alloy can then be distinguished from a random distribution of atoms. In In{sub x}Ga{sub 1-x}N for instance, clustering is detected for concentrations x>0.1. The sensitivity is insufficient to determine whether clustering is present for lower concentrations. HRTEM allows to identify the amplitude and the spatial distribution of the decomposition which is attributed to a spinodal decomposition. In InN, nanometer scale metallic indium inclusions are detected. With decreasing size of the metallic clusters, the photoluminescence of the sample shifts towards the infrared. This indicates that the inclusions may be responsible for the infrared activity of InN. Finally, ZnO grown homoepitaxially on zinc-face and oxygen-face substrates is studied. The O-face epilayer is strained whereas the Zn-face epilayer is almost strain free and has a higher crystalline quality. Quantitative analysis of exit wave phases is in good agreement with simulations, but the signal to noise ratio needs to be improved for the detection of single point defects. (orig.)

  4. Chemical inhomogeneity in InxGa1-xN and ZnO. A HRTEM study on atomic scale clustering

    International Nuclear Information System (INIS)

    Bartel, T.P.

    2008-01-01

    Nanostructuration as well as the nucleation and growth of nanoparticles pervades the development of modern materials and devices. Quantitative high resolution transmission electron microscopy (HRTEM) is currently being developed for a structural and chemical analysis at an atomic scale. It is used in this thesis to study the chemical inhomogeneity and clustering in In x Ga 1-x N, InN and ZnO. A methodology for reliable quantitative HRTEM is rst de ned: it necessitates a damage free sample, the avoidance of electron beam damage and the control of microscope instabilities. With these conditions satis ed, the reliability of quantitative HRTEM is demonstrated by an accurate measurement of lattice relaxation in a thin TEM sample. Clustering in an alloy can then be distinguished from a random distribution of atoms. In In x Ga 1-x N for instance, clustering is detected for concentrations x>0.1. The sensitivity is insufficient to determine whether clustering is present for lower concentrations. HRTEM allows to identify the amplitude and the spatial distribution of the decomposition which is attributed to a spinodal decomposition. In InN, nanometer scale metallic indium inclusions are detected. With decreasing size of the metallic clusters, the photoluminescence of the sample shifts towards the infrared. This indicates that the inclusions may be responsible for the infrared activity of InN. Finally, ZnO grown homoepitaxially on zinc-face and oxygen-face substrates is studied. The O-face epilayer is strained whereas the Zn-face epilayer is almost strain free and has a higher crystalline quality. Quantitative analysis of exit wave phases is in good agreement with simulations, but the signal to noise ratio needs to be improved for the detection of single point defects. (orig.)

  5. Photocatalytic mechanism of high-activity anatase TiO2 with exposed (001) facets from molecular-atomic scale: HRTEM and Raman studies

    Science.gov (United States)

    Wu, Jun; Shi, Chentian; Zhang, Yupeng; Fu, Qiang; Pan, Chunxu

    2017-12-01

    Anatase TiO2 with a variant percentage of exposed (001) facets was prepared under hydrothermal processes by adjusting the volume of HF, and the photocatalytic mechanism was studied from atomic-molecular scale by HRTEM and Raman spectroscopy. It was revealed that: 1) From HRTEM observations, the surface of original TiO2 with exposed (001) facets was clean without impurity, and the crystal lattice was clear and completed; however, when mixed with methylene blue (MB) solution, there were many 1 nm molecular absorbed at the surface of TiO2; after the photocatalytic experiment, MB molecules disappeared and the TiO2 lattice image became fuzzy. 2) The broken path of the MB chemical bond was obtained by Raman spectroscopy, i.e., after the irradiation of the light, the vibrational mode of C-N-C disappeared due to the chemical bond breakage, and the groups containing C-N bond and carbon rings were gradually decomposed. Accordingly, we propose that the driving force for breaking the chemical bond and the disappearance of groups is from the surface lattice distortion of TiO2 during photocatalyzation.

  6. Quantitative atom column position analysis at the incommensurate interfaces of a (PbS)1.14NbS2 misfit layered compound with aberration-corrected HRTEM

    International Nuclear Information System (INIS)

    Garbrecht, M.; Spiecker, E.; Tillmann, K.; Jaeger, W.

    2011-01-01

    Aberration-corrected HRTEM is applied to explore the potential of NCSI contrast imaging to quantitatively analyse the complex atomic structure of misfit layered compounds and their incommensurate interfaces. Using the (PbS) 1.14 NbS 2 misfit layered compound as a model system it is shown that atom column position analyses at the incommensurate interfaces can be performed with precisions reaching a statistical accuracy of ±6 pm. The procedure adopted for these studies compares experimental images taken from compound regions free of defects and interface modulations with a structure model derived from XRD experiments and with multi-slice image simulations for the corresponding NCSI contrast conditions used. The high precision achievable in such experiments is confirmed by a detailed quantitative analysis of the atom column positions at the incommensurate interfaces, proving a tetragonal distortion of the monochalcogenide sublattice. -- Research Highlights: → Quantitative aberration-corrected HRTEM analysis of atomic column positions in (PbS) 1.14 NbS 2 misfit layered compound reveals tetragonal distortion of the PbS subsystem. → Detailed comparison of multi-slice simulations with the experimental NCSI contrast condition imaging results lead to a high precision (better than 10 pm) for determining the positions of atoms. → Precision in gaining information of local structure at atomic scale is demonstrated, which may not be accessible by means of X-ray and neutron diffraction analysis.

  7. MEGACELL: A nanocrystal model construction software for HRTEM multislice simulation

    International Nuclear Information System (INIS)

    Stroppa, Daniel G.; Righetto, Ricardo D.; Montoro, Luciano A.; Ramirez, Antonio J.

    2011-01-01

    Image simulation has an invaluable importance for the accurate analysis of High Resolution Transmission Electron Microscope (HRTEM) results, especially due to its non-linear image formation mechanism. Because the as-obtained images cannot be interpreted in a straightforward fashion, the retrieval of both qualitative and quantitative information from HRTEM micrographs requires an iterative process including the simulation of a nanocrystal model and its comparison with experimental images. However most of the available image simulation software requires atom-by-atom coordinates as input for the calculations, which can be prohibitive for large finite crystals and/or low-symmetry systems and zone axis orientations. This paper presents an open source citation-ware tool named MEGACELL, which was developed to assist on the construction of nanocrystals models. It allows the user to build nanocrystals with virtually any convex polyhedral geometry and to retrieve its atomic positions either as a plain text file or as an output compatible with EMS (Electron Microscopy Software) input protocol. In addition to the description of this tool features, some construction examples and its application for scientific studies are presented. These studies show MEGACELL as a handy tool, which allows an easier construction of complex nanocrystal models and improves the quantitative information extraction from HRTEM images. -- Highlights: → A software to support the HRTEM image simulation of nanocrystals in actual size. → MEGACELL allows the construction of complex nanocrystals models for multislice image simulation. → Some examples of improved nanocrystalline system characterization are presented, including the analysis of 3D morphology and growth behavior.

  8. Conduction of molecular electronic devices: Qualitative insights through atom-atom polarizabilities

    International Nuclear Information System (INIS)

    Stuyver, T.; Fias, S.; De Proft, F.; Geerlings, P.; Fowler, P. W.

    2015-01-01

    The atom-atom polarizability and the transmission probability at the Fermi level, as obtained through the source-and-sink-potential method for every possible configuration of contacts simultaneously, are compared for polycyclic aromatic compounds. This comparison leads to the conjecture that a positive atom-atom polarizability is a necessary condition for transmission to take place in alternant hydrocarbons without non-bonding orbitals and that the relative transmission probability for different configurations of the contacts can be predicted by analyzing the corresponding atom-atom polarizability. A theoretical link between the two considered properties is derived, leading to a mathematical explanation for the observed trends for transmission based on the atom-atom polarizability

  9. Conduction of molecular electronic devices: Qualitative insights through atom-atom polarizabilities

    Energy Technology Data Exchange (ETDEWEB)

    Stuyver, T.; Fias, S., E-mail: sfias@vub.ac.be; De Proft, F.; Geerlings, P. [ALGC, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussel (Belgium); Fowler, P. W. [Department of Chemistry, University of Sheffield, Sheffield S3 7HF (United Kingdom)

    2015-03-07

    The atom-atom polarizability and the transmission probability at the Fermi level, as obtained through the source-and-sink-potential method for every possible configuration of contacts simultaneously, are compared for polycyclic aromatic compounds. This comparison leads to the conjecture that a positive atom-atom polarizability is a necessary condition for transmission to take place in alternant hydrocarbons without non-bonding orbitals and that the relative transmission probability for different configurations of the contacts can be predicted by analyzing the corresponding atom-atom polarizability. A theoretical link between the two considered properties is derived, leading to a mathematical explanation for the observed trends for transmission based on the atom-atom polarizability.

  10. Conduction of molecular electronic devices: qualitative insights through atom-atom polarizabilities.

    Science.gov (United States)

    Stuyver, T; Fias, S; De Proft, F; Fowler, P W; Geerlings, P

    2015-03-07

    The atom-atom polarizability and the transmission probability at the Fermi level, as obtained through the source-and-sink-potential method for every possible configuration of contacts simultaneously, are compared for polycyclic aromatic compounds. This comparison leads to the conjecture that a positive atom-atom polarizability is a necessary condition for transmission to take place in alternant hydrocarbons without non-bonding orbitals and that the relative transmission probability for different configurations of the contacts can be predicted by analyzing the corresponding atom-atom polarizability. A theoretical link between the two considered properties is derived, leading to a mathematical explanation for the observed trends for transmission based on the atom-atom polarizability.

  11. Multislice simulations for in-situ HRTEM studies of nanostructured magnesium hydride at ambient hydrogen pressure

    Energy Technology Data Exchange (ETDEWEB)

    Surrey, Alexander, E-mail: a.surrey@ifw-dresden.de [IFW Dresden, Institute for Metallic Materials, P.O. Box 270116, D-01171 Dresden (Germany); Institut für Festkörperphysik, Technische Universität Dresden, D-01062 Dresden (Germany); Schultz, Ludwig [IFW Dresden, Institute for Metallic Materials, P.O. Box 270116, D-01171 Dresden (Germany); Institut für Festkörperphysik, Technische Universität Dresden, D-01062 Dresden (Germany); Rellinghaus, Bernd, E-mail: b.rellinghaus@ifw-dresden.de [IFW Dresden, Institute for Metallic Materials, P.O. Box 270116, D-01171 Dresden (Germany)

    2017-04-15

    Highlights: • Multislice HRTEM contrast simulations of a windowed environmental cell. • Study of Mg and MgH2 nanocrystals as model system in hydrogen at ambient pressure. • Investigation of spatial resolution and contrast depending on specimen thickness, defocus, and hydrogen pressure. • Atomic resolution is expected for specimens as thin as 5  nm. - Abstract: The use of transmission electron microscopy (TEM) for the structural characterization of many nanostructured hydrides, which are relevant for solid state hydrogen storage, is hindered due to a rapid decomposition of the specimen upon irradiation with the electron beam. Environmental TEM allows to stabilize the hydrides by applying a hydrogen back pressure of up to 4.5 bar in a windowed environmental cell. The feasibility of high-resolution TEM (HRTEM) investigations of light weight metals and metal hydrides in such a “nanoreactor” is studied theoretically by means of multislice HRTEM contrast simulations using Mg and its hydride phase, MgH{sub 2}, as model system. Such a setup provides the general opportunity to study dehydrogenation and hydrogenation reactions at the nanoscale under technological application conditions. We analyze the dependence of both the spatial resolution and the HRTEM image contrast on parameters such as the defocus, the metal/hydride thickness, and the hydrogen pressure in order to explore the possibilities and limitations of in-situ experiments with windowed environmental cells. Such simulations may be highly valuable to pre-evaluate future experimental studies.

  12. Multislice simulations for in-situ HRTEM studies of nanostructured magnesium hydride at ambient hydrogen pressure

    International Nuclear Information System (INIS)

    Surrey, Alexander; Schultz, Ludwig; Rellinghaus, Bernd

    2017-01-01

    Highlights: • Multislice HRTEM contrast simulations of a windowed environmental cell. • Study of Mg and MgH2 nanocrystals as model system in hydrogen at ambient pressure. • Investigation of spatial resolution and contrast depending on specimen thickness, defocus, and hydrogen pressure. • Atomic resolution is expected for specimens as thin as 5  nm. - Abstract: The use of transmission electron microscopy (TEM) for the structural characterization of many nanostructured hydrides, which are relevant for solid state hydrogen storage, is hindered due to a rapid decomposition of the specimen upon irradiation with the electron beam. Environmental TEM allows to stabilize the hydrides by applying a hydrogen back pressure of up to 4.5 bar in a windowed environmental cell. The feasibility of high-resolution TEM (HRTEM) investigations of light weight metals and metal hydrides in such a “nanoreactor” is studied theoretically by means of multislice HRTEM contrast simulations using Mg and its hydride phase, MgH_2, as model system. Such a setup provides the general opportunity to study dehydrogenation and hydrogenation reactions at the nanoscale under technological application conditions. We analyze the dependence of both the spatial resolution and the HRTEM image contrast on parameters such as the defocus, the metal/hydride thickness, and the hydrogen pressure in order to explore the possibilities and limitations of in-situ experiments with windowed environmental cells. Such simulations may be highly valuable to pre-evaluate future experimental studies.

  13. HRTEM study of α-AlMnSi crystals including non-crystallographic projection axes

    International Nuclear Information System (INIS)

    Song, G.L.; Bursill, L.A.

    1997-01-01

    The structure of α-AlMnSi is examined by atomic resolution high-resolution transmission electron microscopy (HRTEM) and computer-based image matching techniques. Six distinct zone axes are examined; including both normal crystallographic and non-crystallographic zones axes of the structural motifs, which have m3-bar 5 icosahedral symmetry. The results provide a sound basis for understanding HRTEM images of the quasicrystalline alloy i-AlMnSi; thus it was examined to what extent the requirements for obtaining so-called structure images of complex alloy structures may be met experimentally and define when the images may be reliably interpreted on the basis of computer simulation and image-matching at about 0.17nm resolution. Most difficulty was experienced in obtaining the experimental images, especially for the non-crystallographic zones, which are very sensitive to slight changes in orientation off the desired zone axis or projection, the rate at which the crystal thickness is increasing (wedge-angle) and the orientation of the surfaces of the specimen. Surface amorphous layers due to oxidation and/or electron-induced irradiation damage also limit the efficiency of the HRTEM analysis. For the thin specimens used for HRTEM, both the electron diffraction patterns and the HRTEM images are characteristic of Im3-bar space group symmetry. It is suggested that this Im3-bar symmetry may be an example of a statistical symmetry, where the local symmetry is close to Pm3-bar but the average symmetry is Im3-bar. The transition from Pm3-bar to Im3-bar may be understood in terms of an analysis of small changes in the outer shells of the large icosahedral structural elements which are located at the corners and body-centers of the cubic unit cell. 21 refs., 3 tabs., 10 figs

  14. HRTEM study of {alpha}-AlMnSi crystals including non-crystallographic projection axes

    Energy Technology Data Exchange (ETDEWEB)

    Song, G.L.; Bursill, L.A.

    1997-06-01

    The structure of {alpha}-AlMnSi is examined by atomic resolution high-resolution transmission electron microscopy (HRTEM) and computer-based image matching techniques. Six distinct zone axes are examined; including both normal crystallographic and non-crystallographic zones axes of the structural motifs, which have m3-bar 5 icosahedral symmetry. The results provide a sound basis for understanding HRTEM images of the quasicrystalline alloy i-AlMnSi; thus it was examined to what extent the requirements for obtaining so-called structure images of complex alloy structures may be met experimentally and define when the images may be reliably interpreted on the basis of computer simulation and image-matching at about 0.17nm resolution. Most difficulty was experienced in obtaining the experimental images, especially for the non-crystallographic zones, which are very sensitive to slight changes in orientation off the desired zone axis or projection, the rate at which the crystal thickness is increasing (wedge-angle) and the orientation of the surfaces of the specimen. Surface amorphous layers due to oxidation and/or electron-induced irradiation damage also limit the efficiency of the HRTEM analysis. For the thin specimens used for HRTEM, both the electron diffraction patterns and the HRTEM images are characteristic of Im3-bar space group symmetry. It is suggested that this Im3-bar symmetry may be an example of a statistical symmetry, where the local symmetry is close to Pm3-bar but the average symmetry is Im3-bar. The transition from Pm3-bar to Im3-bar may be understood in terms of an analysis of small changes in the outer shells of the large icosahedral structural elements which are located at the corners and body-centers of the cubic unit cell. 21 refs., 3 tabs., 10 figs.

  15. HRTEM studies of dislocations in cubic BN

    International Nuclear Information System (INIS)

    Nistor, L.C.; Tendeloo, G. van; Dinca, G.

    2004-01-01

    The atomic structure of dislocations in cubic boron nitride has been investigated by high resolution transmission electron microscopy. Most of the perfect dislocations, screw and 60 edge, are dissociated. A 60 dislocation which was undissociated has been analysed. Computer simulation is performed in an attempt to characterise the core structure. Twinning dislocations and dislocations resulting from the intersection of stacking faults are also revealed. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  16. HRTEM studies of dislocations in cubic BN

    Energy Technology Data Exchange (ETDEWEB)

    Nistor, L.C. [National Institute for Materials Physics, P.O. Box MG-7 Magurele, 077125 Bucharest (Romania); Tendeloo, G. van [University of Antwerp, EMAT, Groenenborgerlaan 171, 2020 Antwerp (Belgium); Dinca, G. [Dacia Synthetic Diamond Factory, Timisoara av. 5, P.O. Box 58-52, 077350 Bucharest (Romania)

    2004-09-01

    The atomic structure of dislocations in cubic boron nitride has been investigated by high resolution transmission electron microscopy. Most of the perfect dislocations, screw and 60 edge, are dissociated. A 60 dislocation which was undissociated has been analysed. Computer simulation is performed in an attempt to characterise the core structure. Twinning dislocations and dislocations resulting from the intersection of stacking faults are also revealed. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  17. On the influence of the electron dose rate on the HRTEM image contrast

    Energy Technology Data Exchange (ETDEWEB)

    Barthel, Juri, E-mail: ju.barthel@fz-juelich.de [RWTH Aachen University, Ahornstraße 55, 52074 Aachen (Germany); Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich GmbH, 52425 Jülich (Germany); Lentzen, Markus; Thust, Andreas [Peter Grünberg Institute, Forschungszentrum Jülich GmbH, 52425 Jülich (Germany); Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich GmbH, 52425 Jülich (Germany)

    2017-05-15

    We investigate a possible dependence between the applied electron dose-rate and the magnitude of the resulting image contrast in HRTEM of inorganic crystalline objects. The present study is focussed on the question whether electron irradiation can induce excessively strong atom vibrations or displacements, which in turn could significantly reduce the resulting image contrast. For this purpose, high-resolution images of MgO, Ge, and Au samples were acquired with varying dose rates using a C{sub S}-corrected FEI Titan 80–300 microscope operated at 300 kV accelerating voltage. This investigation shows that the magnitude of the signal contrast is independent from the dose rates occurring in conventional HRTEM experiments and that excessively strong vibrations or displacements of bulk atoms are not induced by the applied electron irradiation. - Highlights: • No dependence between electron dose rate and HRTEM image contrast is found. • This finding is in full accordance with established solid-state physics theory. • Object-related causes for the previous Stobbs-factor phenomenon are ruled out.

  18. Simulation of bonding effects in HRTEM images of light element materials

    Directory of Open Access Journals (Sweden)

    Simon Kurasch

    2011-07-01

    Full Text Available The accuracy of multislice high-resolution transmission electron microscopy (HRTEM simulation can be improved by calculating the scattering potential using density functional theory (DFT. This approach accounts for the fact that electrons in the specimen are redistributed according to their local chemical environment. This influences the scattering process and alters the absolute and relative contrast in the final image. For light element materials with well defined geometry, such as graphene and hexagonal boron nitride monolayers, the DFT based simulation scheme turned out to be necessary to prevent misinterpretation of weak signals, such as the identification of nitrogen substitutions in a graphene network. Furthermore, this implies that the HRTEM image does not only contain structural information (atom positions and atomic numbers. Instead, information on the electron charge distribution can be gained in addition.In order to produce meaningful results, the new input parameters need to be chosen carefully. Here we present details of the simulation process and discuss the influence of the main parameters on the final result. Furthermore we apply the simulation scheme to three model systems: A single atom boron and a single atom oxygen substitution in graphene and an oxygen adatom on graphene.

  19. HRTEM Study of the Role of Nanoparticles in ODS Ferritic Steel

    Energy Technology Data Exchange (ETDEWEB)

    Hsiung, L; Tumey, S; Fluss, M; Serruys, Y; Willaime, F

    2011-08-30

    Structures of nanoparticles and their role in dual-ion irradiated Fe-16Cr-4.5Al-0.3Ti-2W-0.37Y{sub 2}O{sub 3} (K3) ODS ferritic steel produced by mechanical alloying (MA) were studied using high-resolution transmission electron microscopy (HRTEM) techniques. The observation of Y{sub 4}Al{sub 2}O{sub 9} complex-oxide nanoparticles in the ODS steel imply that decomposition of Y{sub 2}O{sub 3} in association with internal oxidation of Al occurred during mechanical alloying. HRTEM observations of crystalline and partially crystalline nanoparticles larger than {approx}2 nm and amorphous cluster-domains smaller than {approx}2 nm provide an insight into the formation mechanism of nanoparticles/clusters in MA/ODS steels, which we believe involves solid-state amorphization and re-crystallization. The role of nanoparticles/clusters in suppressing radiation-induced swelling is revealed through TEM examinations of cavity distributions in (Fe + He) dual-ion irradiated K3-ODS steel. HRTEM observations of helium-filled cavities (helium bubbles) preferably trapped at nanoparticle/clusters in dual-ion irradiated K3-ODS are presented.

  20. HRTEM investigation of orthorhombic phase in Mg-PSZ

    International Nuclear Information System (INIS)

    Liu, Z.W.; Spargo, A.E.C.; Hannink, R.H.J.

    1997-01-01

    Tetragonal, orthorhombic and monoclinic phases are only slight distortions of the cubic structure. Due to minor differences in unit cell parameters it is difficult to distinguish these phases only by high resolution images. However, using high resolution transmission electron microscopy (HRTEM) observation in combination with image simulation and digital Fourier transformation of HRTEM images, it was found that one tetragonal precipitate can be transformed to several orthorhombic domains with different orientations in MgO-partially-stabilized zirconia (Mg-PSZ). The lattice correspondence between two adjacent orthorhombic domains is such that their b axes are parallel, while their a axes are perpendicular to each other. Also it was found that cubic ZrO 2 could be transformed to orthorhombic ZrO 2 . 8 refs., 1 tab., 4 figs

  1. Mechanisms of heterogeneous crystal growth in atomic systems: insights from computer simulations.

    Science.gov (United States)

    Gulam Razul, M S; Hendry, J G; Kusalik, P G

    2005-11-22

    In this paper we analyze the atomic-level structure of solid/liquid interfaces of Lennard-Jones fcc systems. The 001, 011, and 111 faces are examined during steady-state growth and melting of these crystals. The mechanisms of crystallization and melting are explored using averaged configurations generated during these steady-state runs, where subsequent tagging and labeling of particles at the interface provide many insights into the detailed atomic behavior at the freezing and melting interfaces. The interfaces are generally found to be rough and we observe the structure of freezing and melting interfaces to be very similar. Large structural fluctuations with solidlike and liquidlike characteristics are apparent in both the freezing and melting interfaces. The behavior at the interface observed under either growth or melting conditions reflects a competition between ordering and disordering processes. In addition, we observe atom hopping that imparts liquidlike characteristics to the solid side of the interfaces for all three crystal faces. Solid order is observed to extend as rough, three-dimensional protuberances through the interface, particularly for the 001 and 011 faces. We are also able to reconcile our different measures for the interfacial width and address the onset of asymmetry in the growth rates at high rates of crystal growth/melting.

  2. Design Principles for the Atomic and Electronic Structure of Halide Perovskite Photovoltaic Materials: Insights from Computation.

    Science.gov (United States)

    Berger, Robert F

    2018-02-09

    In the current decade, perovskite solar cell research has emerged as a remarkably active, promising, and rapidly developing field. Alongside breakthroughs in synthesis and device engineering, halide perovskite photovoltaic materials have been the subject of predictive and explanatory computational work. In this Minireview, we focus on a subset of this computation: density functional theory (DFT)-based work highlighting the ways in which the electronic structure and band gap of this class of materials can be tuned via changes in atomic structure. We distill this body of computational literature into a set of underlying design principles for the band gap engineering of these materials, and rationalize these principles from the viewpoint of band-edge orbital character. We hope that this perspective provides guidance and insight toward the rational design and continued improvement of perovskite photovoltaics. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. The Peak Pairs algorithm for strain mapping from HRTEM images

    Energy Technology Data Exchange (ETDEWEB)

    Galindo, Pedro L. [Departamento de Lenguajes y Sistemas Informaticos, CASEM, Universidad de Cadiz, Pol. Rio San Pedro s/n. 11510, Puerto Real, Cadiz (Spain)], E-mail: pedro.galindo@uca.es; Kret, Slawomir [Institute of Physics, PAS, AL. Lotnikow 32/46, 02-668 Warsaw (Poland); Sanchez, Ana M. [Departamento de Ciencia de los Materiales e Ing. Metalurgica y Q. Inorganica, Facultad de Ciencias, Universidad de Cadiz, Pol. Rio San Pedro s/n. 11510, Puerto Real, Cadiz (Spain); Laval, Jean-Yves [Laboratoire de Physique du Solide, UPR5 CNRS-ESPCI, Paris (France); Yanez, Andres; Pizarro, Joaquin; Guerrero, Elisa [Departamento de Lenguajes y Sistemas Informaticos, CASEM, Universidad de Cadiz, Pol. Rio San Pedro s/n. 11510, Puerto Real, Cadiz (Spain); Ben, Teresa; Molina, Sergio I. [Departamento de Ciencia de los Materiales e Ing. Metalurgica y Q. Inorganica, Facultad de Ciencias, Universidad de Cadiz, Pol. Rio San Pedro s/n. 11510, Puerto Real, Cadiz (Spain)

    2007-11-15

    Strain mapping is defined as a numerical image-processing technique that measures the local shifts of image details around a crystal defect with respect to the ideal, defect-free, positions in the bulk. Algorithms to map elastic strains from high-resolution transmission electron microscopy (HRTEM) images may be classified into two categories: those based on the detection of peaks of intensity in real space and the Geometric Phase approach, calculated in Fourier space. In this paper, we discuss both categories and propose an alternative real space algorithm (Peak Pairs) based on the detection of pairs of intensity maxima in an affine transformed space dependent on the reference area. In spite of the fact that it is a real space approach, the Peak Pairs algorithm exhibits good behaviour at heavily distorted defect cores, e.g. interfaces and dislocations. Quantitative results are reported from experiments to determine local strain in different types of semiconductor heterostructures.

  4. Theoretical insight into an empirical rule about organic corrosion inhibitors containing nitrogen, oxygen, and sulfur atoms

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Lei, E-mail: cqglei@163.com [School of Material and Chemical Engieering, Tongren University, Tongren 554300 (China); Obot, Ime Bassey [Center of Research Excellence in Corrosion, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Zheng, Xingwen [Material Corrosion and Protection Key Laboratory of Sichuan province, Zigong 643000 (China); Shen, Xun [School of Material and Chemical Engieering, Tongren University, Tongren 554300 (China); Qiang, Yujie [Material Corrosion and Protection Key Laboratory of Sichuan province, Zigong 643000 (China); Kaya, Savaş; Kaya, Cemal [Department of Chemistry, Faculty of Science, Cumhuriyet University, Sivas 58140 (Turkey)

    2017-06-01

    Highlights: • We obtained the habit information of α-Fe obtained by the “Morphology” module. • The adsorption of pyrrole, furan, and thiophene on Fe(110) surface were studied by DFT calculations. • Our DFT modeling provided a reasonable micro-explanation to the empirical rule. - Abstract: Steel is an important material in industry. Adding heterocyclic organic compounds have proved to be very efficient for steel protection. There exists an empirical rule that the general trend in the inhibition efficiencies of molecules containing heteroatoms is such that O < N < S. However, an atomic-level insight into the inhibition mechanism is still lacked. Thus, in this work, density functional theory calculations was used to investigate the adsorption of three typical heterocyclic molecules, i.e., pyrrole, furan, and thiophene, on Fe(110) surface. The approach is illustrated by carrying out geometric optimization of inhibitors on the stable and most exposed plane of α-Fe. Some salient features such as charge density difference, changes of work function, density of states were detailedly described. The present study is helpful to understand the afore-mentioned experiment rule.

  5. Ceramic/metal nanocomposites by lyophilization: Processing and HRTEM study

    International Nuclear Information System (INIS)

    Gutierrez-Gonzalez, C.F.; Agouram, S.; Torrecillas, R.; Moya, J.S.; Lopez-Esteban, S.

    2012-01-01

    Highlights: ► A cryogenic route has been used to obtain ceramic/metal nanostructured powders. ► The powders present good homogeneity and dispersion of metal. ► The metal nanoparticle size distributions are centred in 17–35 nm. ► Both phases, ceramic and metal, present a high degree of crystallinity. ► Good metal/ceramic interfaces due to epitaxial growth, studied by HRTEM. -- Abstract: This work describes a wet-processing route based on spray-freezing and subsequent lyophilization designed to obtain nanostructured ceramic/metal powders. Starting from the ceramic powder and the corresponding metal salt, a water-based suspension is sprayed on liquid nitrogen. The frozen powders are subsequently freeze-dried, calcined and reduced. The material was analyzed using X-ray diffraction analysis at all stages. High resolution transmission electron microscopy studies showed a uniform distribution of metal nanoparticles on the ceramic grain surfaces, good interfaces and high crystallinity, with an average metal particle size in the nanometric range.

  6. Combined HRTEM and PEELS analysis of nanoporous and amorphous carbon

    International Nuclear Information System (INIS)

    Peng, J.L.; Fan, X. D.; Bursill, L.A.

    1997-01-01

    Both the mass density (1.37 kgm/m 3 ) and sp 2 +sp 3 bonding fraction (0.15) were determined for an unusual nanoporous amorphous carbon consisting of curved single graphitic sheets. A combination of high-resolution transmission electron microscopy (HRTEM) and parallel electron energy loss spectroscopy (PEELS) was used. The values of these two parameters provide important constraints for the determination of the structure of this relatively low density variety of nanoporous carbon. The results are relevant also in the search for negatively-curved Schwarzite-related carbon structures. New date are also presented for highly-oriented pyrollytic graphite (HOPG), chemically vapour deposited (CVD) diamond, C 60 , glassy carbon (GC) and evaporated amorphous carbon (EAC); these are compared with the results for NAC. Kramers-Kronig analysis (KKA) of the low-loss PEELS data shows that the band gaps of both NAC and EAC are collapsed relative to that of CVD diamond. 18 refs., 2 tabs., 3 figs

  7. Combined HRTEM and PEELS analysis of nanoporous and amorphous carbon

    Energy Technology Data Exchange (ETDEWEB)

    Peng, J.L.; Fan, X. D.; Bursill, L.A.

    1997-06-01

    Both the mass density (1.37 kgm/m{sup 3}) and sp{sup 2}+sp{sup 3} bonding fraction (0.15) were determined for an unusual nanoporous amorphous carbon consisting of curved single graphitic sheets. A combination of high-resolution transmission electron microscopy (HRTEM) and parallel electron energy loss spectroscopy (PEELS) was used. The values of these two parameters provide important constraints for the determination of the structure of this relatively low density variety of nanoporous carbon. The results are relevant also in the search for negatively-curved Schwarzite-related carbon structures. New date are also presented for highly-oriented pyrollytic graphite (HOPG), chemically vapour deposited (CVD) diamond, C{sub 60}, glassy carbon (GC) and evaporated amorphous carbon (EAC); these are compared with the results for NAC. Kramers-Kronig analysis (KKA) of the low-loss PEELS data shows that the band gaps of both NAC and EAC are collapsed relative to that of CVD diamond. 18 refs., 2 tabs., 3 figs.

  8. Experimental realization of suspended atomic chains composed of different atomic species

    International Nuclear Information System (INIS)

    Bettini, Jefferson; Ugarte, Daniel; Sato, Fernando; Galvao, Douglas Soares; Coura, Pablo Zimmerman; Dantas, Socrates de Oliveira

    2006-01-01

    We report high resolution transmission electron microscopy (HRTEM) and molecular dynamics results of the first experimental test of suspended atomic chains composed of different atomic species formed from spontaneous stretching of metallic nanowires. (author)

  9. Atom-by-atom engineering of voltage-gated ion channels: Magnified insights into function and pharmacology

    DEFF Research Database (Denmark)

    Pless, Stephan Alexander; Kim, Robin Y; Ahern, Christopher A

    2015-01-01

    Unnatural amino acid incorporation into ion channels has proven to be a valuable approach to interrogate detailed hypotheses arising from atomic resolution structures. In this short review, we provide a brief overview of some of the basic principles and methods for incorporation of unnatural amino...

  10. Automated Structure Detection in HRTEM Images: An Example with Graphene

    DEFF Research Database (Denmark)

    Kling, Jens; Vestergaard, Jacob Schack; Dahl, Anders Bjorholm

    Graphene, as the forefather of 2D-materials, attracts much attention due to its extraordinary properties like transparency, flexibility and outstanding high conductivity, together with a thickness of only one atom. The properties seem to be dependent on the atomic structure of graphene and theref...

  11. Atoms

    International Nuclear Information System (INIS)

    Fuchs, Alain; Villani, Cedric; Guthleben, Denis; Leduc, Michele; Brenner, Anastasios; Pouthas, Joel; Perrin, Jean

    2014-01-01

    Completed by recent contributions on various topics (atoms and the Brownian motion, the career of Jean Perrin, the evolution of atomic physics since Jean Perrin, relationship between scientific atomism and philosophical atomism), this book is a reprint of a book published at the beginning of the twentieth century in which the author addressed the relationship between atomic theory and chemistry (molecules, atoms, the Avogadro hypothesis, molecule structures, solutes, upper limits of molecular quantities), molecular agitation (molecule velocity, molecule rotation or vibration, molecular free range), the Brownian motion and emulsions (history and general features, statistical equilibrium of emulsions), the laws of the Brownian motion (Einstein's theory, experimental control), fluctuations (the theory of Smoluchowski), light and quanta (black body, extension of quantum theory), the electricity atom, the atom genesis and destruction (transmutations, atom counting)

  12. Atomic Insight into the Altered O6-Methylguanine-DNA Methyltransferase Protein Architecture in Gastric Cancer.

    Directory of Open Access Journals (Sweden)

    Naveed Anjum Chikan

    Full Text Available O6-methylguanine-DNA methyltransferase (MGMT is one of the major DNA repair protein that counteracts the alkalyting agent-induced DNA damage by replacing O6-methylguanine (mutagenic lesion back to guanine, eventually suppressing the mismatch errors and double strand crosslinks. Exonic alterations in the form of nucleotide polymorphism may result in altered protein structure that in turn can lead to the loss of function. In the present study, we focused on the population feared for high exposure to alkylating agents owing to their typical and specialized dietary habits. To this end, gastric cancer patients pooled out from the population were selected for the mutational screening of a specific error prone region of MGMT gene. We found that nearly 40% of the studied neoplastic samples harbored missense mutation at codon151 resulting into Serine to Isoleucine variation. This variation resulted in bringing about the structural disorder, subsequently ensuing into a major stoichiometric variance in recognition domain, substrate binding and selectivity loop of the active site of the MGMT protein, as observed under virtual microscope of molecular dynamics simulation (MDS. The atomic insight into MGMT protein by computational approach showed a significant change in the intra molecular hydrogen bond pattern, thus leading to the observed structural anomalies. To further examine the mutational implications on regulatory plugs of MGMT that holds the protein in a DNA-Binding position, a MDS based analysis was carried out on, all known physically interacting amino acids essentially clustered into groups based on their position and function. The results generated by physical-functional clustering of protein indicated that the identified mutation in the vicinity of the active site of MGMT protein causes the local and global destabilization of a protein by either eliminating the stabilizing salt bridges in cluster C3, C4, and C5 or by locally destabilizing the

  13. Atom

    International Nuclear Information System (INIS)

    Auffray, J.P.

    1997-01-01

    The atom through centuries, has been imagined, described, explored, then accelerated, combined...But what happens truly inside the atom? And what are mechanisms who allow its stability? Physicist and historian of sciences, Jean-Paul Auffray explains that these questions are to the heart of the modern physics and it brings them a new lighting. (N.C.)

  14. Insights into the Hydrogen-Atom Transfer of the Blue Aroxyl.

    Science.gov (United States)

    Bächle, Josua; Marković, Marijana; Kelterer, Anne-Marie; Grampp, Günter

    2017-10-19

    An experimental and theoretical study on hydrogen-atom transfer dynamics in the hydrogen-bonded substituted phenol/phenoxyl complex of the blue aroxyl (2,4,6-tri-tert-butylphenoxyl) is presented. The experimental exchange dynamics is determined in different organic solvents from the temperature-dependent alternating line-width effect in the continuous-wave ESR spectrum. From bent Arrhenius plots, effective tunnelling contributions with parallel heavy-atom motion are concluded. To clarify the transfer mechanism, reaction paths for different conformers of the substituted phenol/phenoxyl complex are modelled theoretically. Various DFT and post-Hartree-Fock methods including multireference methods are applied. From the comparison of experimental and theoretical data it is concluded that the system favours concerted hydrogen-atom transfer along a parabolic reaction path caused by heavy-atom motion. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Electronic structure of graphene nanoribbons doped with nitrogen atoms: a theoretical insight.

    Science.gov (United States)

    Torres, A E; Fomine, S

    2015-04-28

    The electronic structure of graphene nanoribbons doped with a graphitic type of nitrogen atoms has been studied using B3LYP, B2PLYP and CAS methods. In all but one case the restricted B3LYP solutions were unstable and the CAS calculations provided evidence for the multiconfigurational nature of the ground state with contributions from two dominant configurations. The relative stability of the doped nanoribbons depends mostly on the mutual position of the dopant atoms and notably less on the position of nitrogen atoms within the nanoribbon. N-graphitic doping affects cationic states much more than anionic ones due the participation of the nitrogen atoms in the stabilization of the positive charge, resulting in a drop in ionization energies (IPs) for N-graphitic doped systems. Nitrogen atoms do not participate in the negative charge stabilization of anionic species and, therefore, the doping does not affect the electron affinities (EAs). The unrestricted B3LYP method is the method of choice for the calculation of IPs and EAs. Restricted B3LYP and B2PLYP produces unreliable results for both IPs and EAs while CAS strongly underestimates the electron affinities. This is also true for the reorganization energies where restricted B3LYP produces qualitatively incorrect results. Doping changes the reorganization energy of the nanoribbons; the hole reorganization energy is generally higher than the corresponding electron reorganization energy due to the participation of nitrogen atoms in the stabilization of the positive charge.

  16. Atomic-scale insight into the origin of pyridine inhibition of MoS2-based hydrotreating catalysts

    DEFF Research Database (Denmark)

    Temel, Burcin; Tuxen, Anders K.; Kibsgaard, Jakob

    2010-01-01

    in earlier IR experiments on high surface alumina-supported MoS2 catalyst. The adsorption sites appear to be very similar to the brim sites involved in hydrogenation reactions in HDS. Thus, the combined STM and DFT results provide new atomic-scale insight into the inhibition effect of basic N......-compounds in HDS and the first direct observation of the adsorption mode of basic N-compounds on the catalytically active MoS2 edges. Our results lend further support to previously reported correlations between inhibiting strength and proton affinity for the N-containing compounds....

  17. Atomic bomb made in Germany. Geo-radar measurements provide new insights

    International Nuclear Information System (INIS)

    Hauk, Rolf-Guenter; Focken, Christel

    2017-01-01

    The authors describe new geo radar measurements In Jonastal and discuss the results in relation to rumors on German efforts to build an atomic bond during the Second World War. The book includes available documentation on German and American research and technological activities (Manhattan project).

  18. Role of cardiolipins in the inner mitochondrial membrane: insight gained through atom-scale simulations

    DEFF Research Database (Denmark)

    Róg, Tomasz; Martinez-Seara, Hector; Munck, Nana

    2009-01-01

    , the exceptional nature of cardiolipins is characterized by their small charged head group connected to typically four hydrocarbon chains. In this work, we present atomic-scale molecular dynamics simulations of the inner mitochondrial membrane modeled as a mixture of cardiolipins (CLs), phosphatidylcholines (PCs...

  19. Atomic substitutions in synthetic apatite; Insights from solid-state NMR spectroscopy

    Science.gov (United States)

    Vaughn, John S.

    Apatite, Ca5(PO4)3X (where X = F, Cl, or OH), is a unique mineral group capable of atomic substitutions for cations and anions of varied size and charge. Accommodation of differing substituents requires some kind of structural adaptation, e.g. new atomic positions, vacancies, or coupled substitutions. These structural adaptations often give rise to important physicochemical properties relevant to a range of scientific disciplines. Examples include volatile trapping during apatite crystallization, substitution for large radionuclides for long-term storage of nuclear fission waste, substitution for fluoride to improve acid resistivity in dental enamel composed dominantly of hydroxylapatite, and the development of novel biomaterials with enhanced biocompatibility. Despite the importance and ubiquity of atomic substitutions in apatite materials, many of the mechanisms by which these reactions occur are poorly understood. Presence of substituents at dilute concentration and occupancy of disordered atomic positions hinder detection by bulk characterization methods such as X-ray diffraction (XRD) and infrared (IR) spectroscopy. Solid-state nuclear magnetic resonance (NMR) spectroscopy is an isotope-specific structural characterization technique that does not require ordered atomic arrangements, and is therefore well suited to investigate atomic substitutions and structural adaptations in apatite. In the present work, solid-state NMR is utilized to investigate structural adaptations in three different types of apatite materials; a series of near-binary F, Cl apatite, carbonate-hydroxylapatite compositions prepared under various synthesis conditions, and a heat-treated hydroxylapatite enriched in 17O. The results indicate that hydroxyl groups in low-H, near binary F,Cl apatite facilitate solid-solution between F and Cl via column reversals, which result in average hexagonal symmetry despite very dilute OH concentration ( 2 mol percent). In addition, 19F NMR spectra indicate

  20. Investigation of the Distribution of Fission Products Silver, Palladium and Cadmium in Neutron Irradiated SIC using a Cs Corrected HRTEM

    Energy Technology Data Exchange (ETDEWEB)

    I. J. van Rooyen; E. Olivier; J. H Neethlin

    2014-10-01

    Electron microscopy examinations of selected coated particles from the first advanced gas reactor experiment (AGR-1) at Idaho National Laboratory (INL) provided important information on fission product distribution and chemical composition. Furthermore, recent research using STEM analysis led to the discovery of Ag at SiC grain boundaries and triple junctions. As these Ag precipitates were nano-sized, high resolution transmission electron microscopy (HRTEM) examination was used to provide more information at the atomic level. This paper describes some of the first HRTEM results obtained by examining a particle from Compact 4-1-1, which was irradiated to an average burnup of 19.26% fissions per initial metal atom (FIMA), a time average, volume-averaged temperature of 1072°C; a time average, peak temperature of 1182°C and an average fast fluence of 4.13 x 1021 n/cm2. Based on gamma analysis, it is estimated that this particle may have released as much as 10% of its available Ag-110m inventory during irradiation. The HRTEM investigation focused on Ag, Pd, Cd and U due to the interest in Ag transport mechanisms and possible correlation with Pd, Ag and U previously found. Additionally, Compact 4-1-1 contains fuel particles fabricated with a different fuel carrier gas composition and lower deposition temperatures for the SiC layer relative to the Baseline fabrication conditions, which are expected to reduce the concentration of SiC defects resulting from uranium dispersion. Pd, Ag, and Cd were found to co-exist in some of the SiC grain boundaries and triple junctions whilst U was found to be present in the micron-sized precipitates as well as separately in selected areas at grain boundaries. This study confirmed the presence of Pd both at inter- and intragranular positions; in the latter case specifically at stacking faults. Small Pd nodules were observed at a distance of about 6.5 micron from the inner PyC/SiC interface.

  1. Insights inot the atomic many-particle dynamics of scattering processes by ab-initio calculations

    International Nuclear Information System (INIS)

    Zapukhlyak, Myroslav

    2008-01-01

    The present thesis gives a theoretical contribution to the understanding of the many-particle dynamics in inelastic ion-atom collisions. Many-electron dynamics in ion-helium collisions and proton-sodium collisions was theoretically studied. The description is based on the semiclassical approximation with the straight orbit for the projectile motion. The ion-atom collision problem is by this reduced to a time-dependent many-electron problem and in the non-relativistic approximation described by the time-dependent Schroedinger equation. The solution of the many-electron problem pursues in the framework of the time-dependent density functional theory. The time-dependent Schroedinger equation for the interacting many-electron problem is transformed to the system of the time-dependent Kohn-Sham equations and solved by the two-center-basis generator method. The unknown time-dependent exchange-correlation one-particle potential forces different approximation int he time-dependent Kohn-Shan scheme. In this thesis the model of the independent electrons was applied as basis model, in which the electron-electron correlation is consistently neglected in all parts and in all steps. Differential cross sections for different one- and two-electron processes were calculated in the so-called eikonal approximation for the collisional systems p-He, He 2+ -He, and Ar q+ -He (q=15-18) [de

  2. Gaining insight into the physics of dynamic atomic force microscopy in complex environments using the VEDA simulator

    Science.gov (United States)

    Kiracofe, Daniel; Melcher, John; Raman, Arvind

    2012-01-01

    Dynamic atomic force microscopy (dAFM) continues to grow in popularity among scientists in many different fields, and research on new methods and operating modes continues to expand the resolution, capabilities, and types of samples that can be studied. But many promising increases in capability are accompanied by increases in complexity. Indeed, interpreting modern dAFM data can be challenging, especially on complicated material systems, or in liquid environments where the behavior is often contrary to what is known in air or vacuum environments. Mathematical simulations have proven to be an effective tool in providing physical insight into these non-intuitive systems. In this article we describe recent developments in the VEDA (virtual environment for dynamic AFM) simulator, which is a suite of freely available, open-source simulation tools that are delivered through the cloud computing cyber-infrastructure of nanoHUB (www.nanohub.org). Here we describe three major developments. First, simulations in liquid environments are improved by enhancements in the modeling of cantilever dynamics, excitation methods, and solvation shell forces. Second, VEDA is now able to simulate many new advanced modes of operation (bimodal, phase-modulation, frequency-modulation, etc.). Finally, nineteen different tip-sample models are available to simulate the surface physics of a wide variety different material systems including capillary, specific adhesion, van der Waals, electrostatic, viscoelasticity, and hydration forces. These features are demonstrated through example simulations and validated against experimental data, in order to provide insight into practical problems in dynamic AFM.

  3. Atomic Force Microscopy Provides New Mechanistic Insights into the Pathogenesis of Pemphigus

    Directory of Open Access Journals (Sweden)

    Franziska Vielmuth

    2018-03-01

    Full Text Available Autoantibodies binding to the extracellular domains of desmoglein (Dsg 3 and 1 are critical in the pathogenesis of pemphigus by mechanisms leading to impaired function of desmosomes and blister formation in the epidermis and mucous membranes. Desmosomes are highly organized protein complexes which provide strong intercellular adhesion. Desmosomal cadherins such as Dsgs, proteins of the cadherin superfamily which interact via their extracellular domains in Ca2+-dependent manner, are the transmembrane adhesion molecules clustered within desmosomes. Investigations on pemphigus cover a wide range of experimental approaches including biophysical methods. Especially atomic force microscopy (AFM has recently been applied increasingly because it allows the analysis of native materials such as cultured cells and tissues under near-physiological conditions. AFM provides information about the mechanical properties of the sample together with detailed interaction analyses of adhesion molecules. With AFM, it was recently demonstrated that autoantibodies directly inhibit Dsg interactions on the surface of living keratinocytes, a phenomenon which has long been considered the main mechanism causing loss of cell cohesion in pemphigus. In addition, AFM allows to study how signaling pathways altered in pemphigus control binding properties of Dsgs. More general, AFM and other biophysical studies recently revealed the importance of keratin filaments for regulation of Dsg binding and keratinocyte mechanical properties. In this mini-review, we reevaluate AFM studies in pemphigus and keratinocyte research, recapitulate what is known about the interaction mechanisms of desmosomal cadherins and discuss the advantages and limitations of AFM in these regards.

  4. Subset geometric phase analysis method for deformation evaluation of HRTEM images

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Hongye [School of Aerospace Engineering, Beijing Institute of Technology, Beijing 100081 (China); Liu, Zhanwei, E-mail: liuzw@bit.edu.cn [School of Aerospace Engineering, Beijing Institute of Technology, Beijing 100081 (China); Wen, Huihui [School of Aerospace Engineering, Beijing Institute of Technology, Beijing 100081 (China); Xie, Huimin, E-mail: xiehm@mail.tsinghua.edu.cn [AML, Department of Engineering Mechanics, Tsinghua University, Beijing 100084 (China); Liu, Chao [Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China)

    2016-12-15

    Geometrical phase analysis (GPA) is typically a powerful tool to investigate the deformation in high resolution transmission electron microscopy images and has been used in various fields. The traditional GPA method using the fast Fourier transform, referred to as global-GPA (G-GPA) here, is based on the relationship between the displacement and the phase difference. In this paper, a subset-GPA (S-GPA) is introduced for further improvement. The S-GPA performs the windowed Fourier transform block by block in the image. The maximum strain measurement scale of the GPA method is theoretically analyzed on the basic of the phase spectrum extraction process. The upper limit is one third of the atomic spacing. The results of various numerical simulations verified that the S-GPA method performs better than the traditional G-GPA method in both the homogeneous and inhomogeneous deformation conditions, with the evaluation parameter of calculation reliability of S-GPA 10% higher than G-GPA. Specifically, the measurement accuracy of S-GPA is about three times higher than the G-GPA when calculating small strain (less than 2000με). For the large strain (greater than 150000με), the measurement accuracy of S-GPA is about 50% higher than that of the G-GPA. Besides, the S-GPA method can significantly eliminate the phase filling effect, while the G-GPA cannot. The S-GPA method has been successfully applied to analyze the strain field distribution in an lnGaAs/InAlAs supperlattice heterostructure. - Highlights: • A subset-GPA method, performing the windowed Fourier transform block by block in HRTEM image, is systematically introduced. • According to the theoretical analysis, the upper limit of absolute maximum strain of GPA method is 1/3. • The measurement accuracy of S-GPA is about three times higher than that of the G-GPA when calculating small strain. • The measurement capability of S-GPA is about 50 percent higher than that of the G-GPA when calculating large strain.

  5. Preformed template fluctuations promote fibril formation: Insights from lattice and all-atom models

    Energy Technology Data Exchange (ETDEWEB)

    Kouza, Maksim, E-mail: mkouza@chem.uw.edu.pl; Kolinski, Andrzej [Faculty of Chemistry, University of Warsaw, ul. Pasteura 1, 02-093 Warszaw (Poland); Co, Nguyen Truong [Department of Physics, Institute of Technology, National University of HCM City, 268 Ly Thuong Kiet Street, District 10, Ho Chi Minh City (Viet Nam); Institute for Computational Science and Technology, Quang Trung Software City, Tan Chanh Hiep Ward, District 12, Ho Chi Minh City (Viet Nam); Nguyen, Phuong H. [Laboratoire de Biochimie Theorique, UPR 9080 CNRS, IBPC, Universite Paris 7, 13 rue Pierre et Marie Curie, 75005 Paris (France); Li, Mai Suan, E-mail: masli@ifpan.edu.pl [Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw (Poland)

    2015-04-14

    Fibril formation resulting from protein misfolding and aggregation is a hallmark of several neurodegenerative diseases such as Alzheimer’s and Parkinson’s diseases. Despite the fact that the fibril formation process is very slow and thus poses a significant challenge for theoretical and experimental studies, a number of alternative pictures of molecular mechanisms of amyloid fibril formation have been recently proposed. What seems to be common for the majority of the proposed models is that fibril elongation involves the formation of pre-nucleus seeds prior to the creation of a critical nucleus. Once the size of the pre-nucleus seed reaches the critical nucleus size, its thermal fluctuations are expected to be small and the resulting nucleus provides a template for sequential (one-by-one) accommodation of added monomers. The effect of template fluctuations on fibril formation rates has not been explored either experimentally or theoretically so far. In this paper, we make the first attempt at solving this problem by two sets of simulations. To mimic small template fluctuations, in one set, monomers of the preformed template are kept fixed, while in the other set they are allowed to fluctuate. The kinetics of addition of a new peptide onto the template is explored using all-atom simulations with explicit water and the GROMOS96 43a1 force field and simple lattice models. Our result demonstrates that preformed template fluctuations can modulate protein aggregation rates and pathways. The association of a nascent monomer with the template obeys the kinetics partitioning mechanism where the intermediate state occurs in a fraction of routes to the protofibril. It was shown that template immobility greatly increases the time of incorporating a new peptide into the preformed template compared to the fluctuating template case. This observation has also been confirmed by simulation using lattice models and may be invoked to understand the role of template fluctuations in

  6. Statistical analysis of support thickness and particle size effects in HRTEM imaging of metal nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    House, Stephen D., E-mail: sdh46@pitt.edu [Chemical and Petroleum Engineering, and Physics, University of Pittsburgh, Pittsburgh, PA 15261 (United States); Bonifacio, Cecile S.; Grieshaber, Ross V.; Li, Long; Zhang, Zhongfan [Chemical and Petroleum Engineering, and Physics, University of Pittsburgh, Pittsburgh, PA 15261 (United States); Ciston, Jim [National Center of Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Stach, Eric A. [Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, NY 11973 (United States); Yang, Judith C. [Chemical and Petroleum Engineering, and Physics, University of Pittsburgh, Pittsburgh, PA 15261 (United States)

    2016-10-15

    High-resolution transmission electron microscopy (HRTEM) examination of nanoparticles requires their placement on some manner of support – either TEM grid membranes or part of the material itself, as in many heterogeneous catalyst systems – but a systematic quantification of the practical imaging limits of this approach has been lacking. Here we address this issue through a statistical evaluation of how nanoparticle size and substrate thickness affects the ability to resolve structural features of interest in HRTEM images of metallic nanoparticles on common support membranes. The visibility of lattice fringes from crystalline Au nanoparticles on amorphous carbon and silicon supports of varying thickness was investigated with both conventional and aberration-corrected TEM. Over the 1–4 nm nanoparticle size range examined, the probability of successfully resolving lattice fringes differed significantly as a function both of nanoparticle size and support thickness. Statistical analysis was used to formulate guidelines for the selection of supports and to quantify the impact a given support would have on HRTEM imaging of crystalline structure. For nanoparticles ≥1 nm, aberration-correction was found to provide limited benefit for the purpose of visualizing lattice fringes; electron dose is more predictive of lattice fringe visibility than aberration correction. These results confirm that the ability to visualize lattice fringes is ultimately dependent on the signal-to-noise ratio of the HRTEM images, rather than the point-to-point resolving power of the microscope. This study provides a benchmark for HRTEM imaging of crystalline supported metal nanoparticles and is extensible to a wide variety of supports and nanostructures. - Highlights: • The impact of supports on imaging nanoparticle lattice structure is quantified. • Visualization probabilities given particle size and support thickness are estimated. • Aberration-correction provided limited benefit

  7. Statistical analysis of support thickness and particle size effects in HRTEM imaging of metal nanoparticles

    International Nuclear Information System (INIS)

    House, Stephen D.; Bonifacio, Cecile S.; Grieshaber, Ross V.; Li, Long; Zhang, Zhongfan; Ciston, Jim; Stach, Eric A.; Yang, Judith C.

    2016-01-01

    High-resolution transmission electron microscopy (HRTEM) examination of nanoparticles requires their placement on some manner of support – either TEM grid membranes or part of the material itself, as in many heterogeneous catalyst systems – but a systematic quantification of the practical imaging limits of this approach has been lacking. Here we address this issue through a statistical evaluation of how nanoparticle size and substrate thickness affects the ability to resolve structural features of interest in HRTEM images of metallic nanoparticles on common support membranes. The visibility of lattice fringes from crystalline Au nanoparticles on amorphous carbon and silicon supports of varying thickness was investigated with both conventional and aberration-corrected TEM. Over the 1–4 nm nanoparticle size range examined, the probability of successfully resolving lattice fringes differed significantly as a function both of nanoparticle size and support thickness. Statistical analysis was used to formulate guidelines for the selection of supports and to quantify the impact a given support would have on HRTEM imaging of crystalline structure. For nanoparticles ≥1 nm, aberration-correction was found to provide limited benefit for the purpose of visualizing lattice fringes; electron dose is more predictive of lattice fringe visibility than aberration correction. These results confirm that the ability to visualize lattice fringes is ultimately dependent on the signal-to-noise ratio of the HRTEM images, rather than the point-to-point resolving power of the microscope. This study provides a benchmark for HRTEM imaging of crystalline supported metal nanoparticles and is extensible to a wide variety of supports and nanostructures. - Highlights: • The impact of supports on imaging nanoparticle lattice structure is quantified. • Visualization probabilities given particle size and support thickness are estimated. • Aberration-correction provided limited benefit

  8. Fundamental insights into the radium uptake into barite by atom probe tomography and electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Weber, Juliane

    2017-10-01

    -of-the-art high-resolution microscopy techniques was used to answer the questions regarding (1) the internal microstructure of the initial barite (2) the role of this internal microstructure during the Ra uptake and (3) t he changes in the Ra distribution within the barite. This study comprises the first characterization of barite by atom probe tomography (APT). By combining APT and transmission electron microscopy (TEM) methods, pores covering the size range from a few nanometers to a few micrometers were identified in the SL barite. The pores were organized in layers parallel to the outer crystal faces. High resolution chemical analysis indicated that the pores contain a solution of water and sodium chloride. By focused ion beam (FIB) tomography, it was revealed that open macropores of several micrometers size are present as well within the SL barite. These partially connected macropores are distributed within the complete barite particles. Therefore, the macropores provide a direct pathway for Ra-containing aqueous fluid to enter the SL barite particles by diffusion within the aqueous solution. In addition, pores were also identified in the AL barite by TEM characterization. The entrapment of solution during mineral precipitation is known for several minerals at high supersaturation. As barite only precipitates at high supersaturation, nanoscale fluid inclusions as well as macropores probably were entrapped during the particle growth by precipitation. A microstructure similar to the one of the barite type used in this study was previously reported for other barites. In Ra-free reference experiment, no microstructural changes were noted over recrystallization times of up to 898 days. In prior studies, three different stages of Ra uptake were described based on macroscopic results. Ra-containing barite samples from all three stages were characterized to understand the role of the internal barite microstructure. At the beginning, the nano-scale fluid inclusions disappeared

  9. Fundamental insights into the radium uptake into barite by atom probe tomography and electron microscopy

    International Nuclear Information System (INIS)

    Weber, Juliane

    2017-01-01

    used to answer the questions regarding (1) the internal microstructure of the initial barite (2) the role of this internal microstructure during the Ra uptake and (3) t he changes in the Ra distribution within the barite. This study comprises the first characterization of barite by atom probe tomography (APT). By combining APT and transmission electron microscopy (TEM) methods, pores covering the size range from a few nanometers to a few micrometers were identified in the SL barite. The pores were organized in layers parallel to the outer crystal faces. High resolution chemical analysis indicated that the pores contain a solution of water and sodium chloride. By focused ion beam (FIB) tomography, it was revealed that open macropores of several micrometers size are present as well within the SL barite. These partially connected macropores are distributed within the complete barite particles. Therefore, the macropores provide a direct pathway for Ra-containing aqueous fluid to enter the SL barite particles by diffusion within the aqueous solution. In addition, pores were also identified in the AL barite by TEM characterization. The entrapment of solution during mineral precipitation is known for several minerals at high supersaturation. As barite only precipitates at high supersaturation, nanoscale fluid inclusions as well as macropores probably were entrapped during the particle growth by precipitation. A microstructure similar to the one of the barite type used in this study was previously reported for other barites. In Ra-free reference experiment, no microstructural changes were noted over recrystallization times of up to 898 days. In prior studies, three different stages of Ra uptake were described based on macroscopic results. Ra-containing barite samples from all three stages were characterized to understand the role of the internal barite microstructure. At the beginning, the nano-scale fluid inclusions disappeared, probably due to coalescing to new macropores

  10. Insights into the Electronic Structure of Ozone and Sulfur Dioxide from Generalized Valence Bond Theory: Addition of Hydrogen Atoms.

    Science.gov (United States)

    Lindquist, Beth A; Takeshita, Tyler Y; Dunning, Thom H

    2016-05-05

    Ozone (O3) and sulfur dioxide (SO2) are valence isoelectronic species, yet their properties and reactivities differ dramatically. In particular, O3 is highly reactive, whereas SO2 is chemically relatively stable. In this paper, we investigate serial addition of hydrogen atoms to both the terminal atoms of O3 and SO2 and to the central atom of these species. It is well-known that the terminal atoms of O3 are much more amenable to bond formation than those of SO2. We show that the differences in the electronic structure of the π systems in the parent triatomic species account for the differences in the addition of hydrogen atoms to the terminal atoms of O3 and SO2. Further, we find that the π system in SO2, which is a recoupled pair bond dyad, facilitates the addition of hydrogen atoms to the sulfur atom, resulting in stable HSO2 and H2SO2 species.

  11. Tetragonal fcc-Fe induced by κ -carbide precipitates: Atomic scale insights from correlative electron microscopy, atom probe tomography, and density functional theory

    Science.gov (United States)

    Liebscher, Christian H.; Yao, Mengji; Dey, Poulumi; Lipińska-Chwalek, Marta; Berkels, Benjamin; Gault, Baptiste; Hickel, Tilmann; Herbig, Michael; Mayer, Joachim; Neugebauer, Jörg; Raabe, Dierk; Dehm, Gerhard; Scheu, Christina

    2018-02-01

    Correlative scanning transmission electron microscopy, atom probe tomography, and density functional theory calculations resolve the correlation between elastic strain fields and local impurity concentrations on the atomic scale. The correlative approach is applied to coherent interfaces in a κ -carbide strengthened low-density steel and establishes a tetragonal distortion of fcc-Fe. An interfacial roughness of ˜1 nm and a localized carbon concentration gradient extending over ˜2 -3 nm is revealed, which originates from the mechano-chemical coupling between local strain and composition.

  12. Influence of total beam current on HRTEM image resolution in differentially pumped ETEM with nitrogen gas.

    Science.gov (United States)

    Bright, A N; Yoshida, K; Tanaka, N

    2013-01-01

    Environmental transmission electron microscopy (ETEM) enables the study of catalytic and other reaction processes as they occur with Angstrom-level resolution. The microscope used is a dedicated ETEM (Titan ETEM, FEI Company) with a differential pumping vacuum system and apertures, allowing aberration corrected high-resolution transmission electron microscopy (HRTEM) imaging to be performed with gas pressures up to 20 mbar in the sample area and with significant advantages over membrane-type E-cell holders. The effect on image resolution of varying the nitrogen gas pressure, electron beam current density and total beam current were measured using information limit (Young's fringes) on a standard cross grating sample and from silicon crystal lattice imaging. As expected, increasing gas pressure causes a decrease in HRTEM image resolution. However, the total electron beam current also causes big changes in the image resolution (lower beam current giving better resolution), whereas varying the beam current density has almost no effect on resolution, a result that has not been reported previously. This behavior is seen even with zero-loss filtered imaging, which we believe shows that the drop in resolution is caused by elastic scattering at gas ions created by the incident electron beam. Suitable conditions for acquiring high resolution images in a gas environment are discussed. Lattice images at nitrogen pressures up to 16 mbar are shown, with 0.12 nm information transfer at 4 mbar. Copyright © 2012 Elsevier B.V. All rights reserved.

  13. Investigation of the Fission Products Silver, Palladium and Cadmium in Neutron Irradiated SiC using a Cs-Corrected HRTEM

    International Nuclear Information System (INIS)

    Rooyen, I.J. van; Olivier, E.J.; Neethling, J.H

    2014-01-01

    Electron microscopy investigations of selected coated particles from the first advanced gas reactor experiment (AGR-1) at Idaho National Laboratory (INL) provided important information on fission product distribution and chemical composition in the SiC layer. Furthermore, recent STEM analyses led to the discovery of Ag at SiC grain boundaries and triple junctions. As these Ag precipitates were nano-sized, high resolution transmission electron microscopy (HRTEM) was used to provide more information at the atomic level. This paper describes some of the first HRTEM results obtained from the examination of a particle from Compact 4-1-1, which was irradiated to an average burnup of 19.38% fissions per initial metal atom (FIMA), a time-average, volume-averaged temperature of 1072°C; a time-average, peak temperature of 1182°C and an average fast fluence of 4.13x10 21 n/cm 2 . Based on gamma-ray analysis, it is estimated that this particle may have released as much as 10% of its available Ag-110m inventory during irradiation. The HRTEM investigation focused on Ag, Pd, and Cd due to the interest in Ag transport mechanisms and possible correlation with Pd and Ag previously found. Additionally, Compact 4-1-1 contains fuel particles fabricated with a different fuel carrier gas composition and lower deposition temperatures for the SiC layer relative to the Baseline fabrication conditions, which are expected to reduce the concentration of SiC defects resulting from uranium dispersion. Small Ag precipitates were observed at a distance of about 6.5 micron from the inner PyC-SiC interface. Pd, Ag, and Cd were found to co-exist in some of the SiC grain boundaries and triple junctions. This study confirmed the presence of Pd both at inter- and intragranular sites; in the latter case specifically at stacking faults. Small Ag precipitates were observed at a distance of about 6.5 microns from the inner PyC/SiC interface. (author)

  14. Fission products silver, palladium, and cadmium identification in neutron-irradiated SiC TRISO particles using a Cs-Corrected HRTEM

    Energy Technology Data Exchange (ETDEWEB)

    Rooyen, I.J. van, E-mail: isabella.vanrooyen@inl.gov [Fuel Design and Development Department, Idaho National Laboratory, P.O. Box 1625, Idaho Falls, ID, 83415-6188 (United States); Olivier, E.J.; Neethling, J.H. [Centre for High Resolution Electron Microscopy, Department of Physics, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa)

    2016-08-01

    Electron microscopy investigations of selected coated particles from the first advanced gas reactor experiment at Idaho National Laboratory provided important information on fission product distribution and chemical composition in the silicon-carbide (SiC) layer. Silver precipitates were nano-sized, and therefore high-resolution transmission electron microscopy (HRTEM) was used to provide more information at the atomic level. Based on gamma-ray analysis, this particle which was irradiated to an average burnup of 19.38% fissions per initial metal atom, may have released as much as 10% of its available Ag-110 m inventory during irradiation. The HRTEM investigation focused on silver, palladium, and cadmium due to interest in silver transport mechanisms and possible correlation with palladium and silver previously found. Palladium, silver, and cadmium were found to co-exist in some of the SiC grain boundaries and triple junctions. This study confirmed palladium both at inter and intragranular sites. Phosphor was identified in SiC grain boundaries and triple points. - Highlights: • First high resolution electron microscopy fission product nano-structural locations of irradiated TRISO coated particles. • Pd observed inside SiC grains in proximity to planar defects e.g. stacking faults. • Ag co-exists with Pd and Cd only may suggest a Pd-assisted transport mechanism. • First finding of neutron transmutation product P, in SiC layer of TRISO coated particles. No direct link to Ag transport. • No significant Pd corrosion of SiC observed even at this high resolution images.

  15. TEM and HRTEM of Soot-in-oil particles and agglomerates from internal combustion engines

    International Nuclear Information System (INIS)

    Fay, M W; Rocca, A La; Shayler, P J

    2014-01-01

    Over time, the performance of lubricating oil in a diesel engine is affected by the build-up of carbon soot produced by the combustion process. TEM and HRTEM are commonly used to investigate the characteristics of individual and agglomerated particles from diesel exhaust, to understand the structure and distribution of the carbon sheets in the primary particles and the nanostructure morphology. However, high resolution imaging of soot-in-oil is more challenging, as mineral oil is a contaminant for the electron microscope and leads to instability under the electron beam. In this work we compare solvent extraction and centrifugation techniques for removing the mineral oil contaminant, and the effect on particle size distribution

  16. Influence of total beam current on HRTEM image resolution in differentially pumped ETEM with nitrogen gas

    International Nuclear Information System (INIS)

    Bright, A.N.; Yoshida, K.; Tanaka, N.

    2013-01-01

    Environmental transmission electron microscopy (ETEM) enables the study of catalytic and other reaction processes as they occur with Angstrom-level resolution. The microscope used is a dedicated ETEM (Titan ETEM, FEI Company) with a differential pumping vacuum system and apertures, allowing aberration corrected high-resolution transmission electron microscopy (HRTEM) imaging to be performed with gas pressures up to 20 mbar in the sample area and with significant advantages over membrane-type E-cell holders. The effect on image resolution of varying the nitrogen gas pressure, electron beam current density and total beam current were measured using information limit (Young's fringes) on a standard cross grating sample and from silicon crystal lattice imaging. As expected, increasing gas pressure causes a decrease in HRTEM image resolution. However, the total electron beam current also causes big changes in the image resolution (lower beam current giving better resolution), whereas varying the beam current density has almost no effect on resolution, a result that has not been reported previously. This behavior is seen even with zero-loss filtered imaging, which we believe shows that the drop in resolution is caused by elastic scattering at gas ions created by the incident electron beam. Suitable conditions for acquiring high resolution images in a gas environment are discussed. Lattice images at nitrogen pressures up to 16 mbar are shown, with 0.12 nm information transfer at 4 mbar. -- Highlights: ► ETEM images with point resolution of 0.12 nm in 4 mbar of nitrogen gas. ► Clear Si lattice imaging with 16 mbar of nitrogen gas. ► ETEM image resolution in gas can be much improved by decreasing total beam current. ► Beam current density (beam convergence) has no effect on the image resolution.

  17. Numerical correction of anti-symmetric aberrations in single HRTEM images of weakly scattering 2D-objects

    International Nuclear Information System (INIS)

    Lehtinen, Ossi; Geiger, Dorin; Lee, Zhongbo; Whitwick, Michael Brian; Chen, Ming-Wei; Kis, Andras; Kaiser, Ute

    2015-01-01

    Here, we present a numerical post-processing method for removing the effect of anti-symmetric residual aberrations in high-resolution transmission electron microscopy (HRTEM) images of weakly scattering 2D-objects. The method is based on applying the same aberrations with the opposite phase to the Fourier transform of the recorded image intensity and subsequently inverting the Fourier transform. We present the theoretical justification of the method, and its verification based on simulated images in the case of low-order anti-symmetric aberrations. Ultimately the method is applied to experimental hardware aberration-corrected HRTEM images of single-layer graphene and MoSe 2 resulting in images with strongly reduced residual low-order aberrations, and consequently improved interpretability. Alternatively, this method can be used to estimate by trial and error the residual anti-symmetric aberrations in HRTEM images of weakly scattering objects

  18. Atomic bomb made in Germany. Geo-radar measurements provide new insights; Atombombe - Made in Germany. Georadarmessungen liefern neue Erkenntnisse

    Energy Technology Data Exchange (ETDEWEB)

    Hauk, Rolf-Guenter; Focken, Christel

    2017-07-01

    The authors describe new geo radar measurements In Jonastal and discuss the results in relation to rumors on German efforts to build an atomic bond during the Second World War. The book includes available documentation on German and American research and technological activities (Manhattan project).

  19. Does the number of nitrogen atoms have an influence on the conducting properties of diphenylazines? A DFT insight

    International Nuclear Information System (INIS)

    Moral, Monica; Granadino-Roldan, Jose Manuel; Garzon, Andres; Garcia, Gregorio; Fernandez-Gomez, Manuel

    2011-01-01

    Research highlights: → Planarity and aromaticity increase when increasing the number of N atoms. → HOMO → LUMO excitation energy decreases when increasing the number of N atoms. → AEA increases stepwise with the number of N atoms up to 1.51 eV for Ph 2 Tz. → Ph 2 Tz becomes the best candidate of the series in terms of electron injection. → Ph 2 T N3 seems to be the best candidate in terms of electron transport. - Abstract: The present study reports on the variation of some structural and electronic properties related to the electron conductivity for the series of diphenylazines represented by the formula Ph-(C 2+n N 4-n H n )-Ph, n = 0 - 4. Properties such as planarity, aromaticity, HOMO → LUMO excitation energy, electron affinity, LUMO level energy, reorganization energy and electron coupling between neighboring molecules in the crystal were analyzed from a theoretical perspective as a function of the number of nitrogen atoms in the molecular structure. As a result, the planarity, aromaticity and electron affinity increase with the number of N atoms in the central ring while the HOMO → LUMO excitation energy and LUMO levels diminish. It is worth noting that up to n = 3, the frontier orbitals appear delocalized throughout the whole system while for n = 4 the localized character of the LUMO might explain the increase in the reorganization energy and thus the higher difficulty to delocalize the excess of negative charge. Electron coupling between neighboring molecules was also estimated on the basis of the energy splitting in dimer method and the reported crystal structures for some of the studied molecules. Accordingly, the highest |t 12 | value was obtained for Ph 2 T N3 (0.06 eV) while Ph 2 Tz should be the most advantageous candidate of the series in terms of electron injection.

  20. HRTEM Study of Oxide Nanoparticles in K3-ODS Ferritic Steel Developed for Radiation Tolerance

    Energy Technology Data Exchange (ETDEWEB)

    Hsiung, L; Fluss, M; Tumey, S; Kuntz, J; El-Dasher, B; Wall, M; Choi, W; Kimura, A; Willaime, F; Serruys, Y

    2009-11-02

    Crystal and interfacial structures of oxide nanoparticles and radiation damage in 16Cr-4.5Al-0.3Ti-2W-0.37 Y{sub 2}O{sub 3} ODS ferritic steel have been examined using high-resolution transmission electron microscopy (HRTEM) techniques. Oxide nanoparticles with a complex-oxide core and an amorphous shell were frequently observed. The crystal structure of complex-oxide core is identified to be mainly monoclinic Y{sub 4}Al{sub 2}O{sub 9} (YAM) oxide compound. Orientation relationships between the oxide and the matrix are found to be dependent on the particle size. Large particles (> 20 nm) tend to be incoherent and have a spherical shape, whereas small particles (< 10 nm) tend to be coherent or semi-coherent and have a faceted interface. The observations of partially amorphous nanoparticles and multiple crystalline domains formed within a nanoparticle lead us to propose a three-stage mechanism to rationalize the formation of oxide nanoparticles containing core/shell structures in as-fabricated ODS steels. Effects of nanoparticle size and density on cavity formation induced by (Fe{sup 8+} + He{sup +}) dual-beam irradiation are briefly addressed.

  1. Comparing electron tomography and HRTEM slicing methods as tools to measure the thickness of nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Alloyeau, D., E-mail: alloyeau.damien@gmail.com [Laboratoire Materiaux et Phenomenes Quantiques, Universite Paris 7/CNRS, UMR 7162, 2 Place Jussieu, 75251 Paris (France); Laboratoire d' Etude des Microstructures - ONERA/CNRS, UMR 104, B.P. 72, 92322 Chatillon (France); Ricolleau, C. [Laboratoire Materiaux et Phenomenes Quantiques, Universite Paris 7/CNRS, UMR 7162, 2 Place Jussieu, 75251 Paris (France); Oikawa, T. [Laboratoire Materiaux et Phenomenes Quantiques, Universite Paris 7/CNRS, UMR 7162, 2 Place Jussieu, 75251 Paris (France); JEOL (Europe) SAS, Espace Claude Monet, 1 Allee de Giverny, 78290 Croissy-sur-Seine (France); Langlois, C. [Laboratoire Materiaux et Phenomenes Quantiques, Universite Paris 7/CNRS, UMR 7162, 2 Place Jussieu, 75251 Paris (France); Le Bouar, Y.; Loiseau, A. [Laboratoire d' Etude des Microstructures - ONERA/CNRS, UMR 104, B.P. 72, 92322 Chatillon (France)

    2009-06-15

    Nanoparticles' morphology is a key parameter in the understanding of their thermodynamical, optical, magnetic and catalytic properties. In general, nanoparticles, observed in transmission electron microscopy (TEM), are viewed in projection so that the determination of their thickness (along the projection direction) with respect to their projected lateral size is highly questionable. To date, the widely used methods to measure nanoparticles thickness in a transmission electron microscope are to use cross-section images or focal series in high-resolution transmission electron microscopy imaging (HRTEM 'slicing'). In this paper, we compare the focal series method with the electron tomography method to show that both techniques yield similar particle thickness in a range of size from 1 to 5 nm, but the electron tomography method provides better statistics since more particles can be analyzed at one time. For this purpose, we have compared, on the same samples, the nanoparticles thickness measurements obtained from focal series with the ones determined from cross-section profiles of tomograms (tomogram slicing) perpendicular to the plane of the substrate supporting the nanoparticles. The methodology is finally applied to the comparison of CoPt nanoparticles annealed ex situ at two different temperatures to illustrate the accuracy of the techniques in detecting small particle thickness changes.

  2. Does the number of nitrogen atoms have an influence on the conducting properties of diphenylazines? A DFT insight

    Science.gov (United States)

    Moral, Mónica; Granadino-Roldán, José Manuel; Garzón, Andrés; García, Gregorio; Fernández-Gómez, Manuel

    2011-01-01

    The present study reports on the variation of some structural and electronic properties related to the electron conductivity for the series of diphenylazines represented by the formula Ph sbnd (C 2+nN 4-nH n) sbnd Ph, n = 0 - 4. Properties such as planarity, aromaticity, HOMO → LUMO excitation energy, electron affinity, LUMO level energy, reorganization energy and electron coupling between neighboring molecules in the crystal were analyzed from a theoretical perspective as a function of the number of nitrogen atoms in the molecular structure. As a result, the planarity, aromaticity and electron affinity increase with the number of N atoms in the central ring while the HOMO → LUMO excitation energy and LUMO levels diminish. It is worth noting that up to n = 3, the frontier orbitals appear delocalized throughout the whole system while for n = 4 the localized character of the LUMO might explain the increase in the reorganization energy and thus the higher difficulty to delocalize the excess of negative charge. Electron coupling between neighboring molecules was also estimated on the basis of the energy splitting in dimer method and the reported crystal structures for some of the studied molecules. Accordingly, the highest | t12| value was obtained for Ph 2T N3 (0.06 eV) while Ph 2Tz should be the most advantageous candidate of the series in terms of electron injection.

  3. Atomic resolution structural insights into PdPt nanoparticle–carbon interactions for the design of highly active and stable electrocatalysts

    International Nuclear Information System (INIS)

    Slanac, Daniel A.; Li Lin; Mayoral, Alvaro; Yacaman, Miguel José; Manthiram, Arumugam; Stevenson, Keith J.; Johnston, Keith P.

    2012-01-01

    Graphical abstract: - Abstract: Interfacial interactions between sub-4 nm metal alloy nanoparticles and carbon supports, although not well understood at the atomic level, may be expected to have a profound influence on catalytic properties. Pd 3 Pt 2 alloy particles comprised of a disordered surface layer over a corrugated crystalline core are shown to exhibit strong interfacial interactions with a ∼20–50 nm spherical carbon support, as characterized by probe aberration corrected scanning transmission electron microscopy (pcSTEM). The disordered shells were formed from defects introduced by Pd during arrested growth synthesis of the alloy nanoparticles. The chemical and morphological changes in the catalyst, before and after cyclic stability testing (1000 cycles, 0.5–1.2 V), were probed with cyclic voltammetry (CV), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and pcSTEM. The strong metal–support interaction, along with the uniform alloy structure raised the mass activity by a factor of 1.8 versus pure Pt. The metal–support interactions also mitigated nanoparticle coalescence, dissolution, and ripening, resulting in only a 20% loss in mass activity (versus 60% for pure Pt on carbon) after the cyclic stability test. The design of alloy structure, guided by insight from atomic scale pcSTEM, for enhanced catalytic activity and stability, resulting from strong wetting with a deformable disordered shell, has the potential to be a general paradigm for improving catalytic performance.

  4. Revealing the nanostructure of calcium phosphate coatings using HRTEM/FIB techniques

    International Nuclear Information System (INIS)

    Solla, E.L.; Rodríguez-González, B.; Aguiar, H.; Rodríguez-Valencia, C.; Serra, J.; González, P.

    2016-01-01

    Herein, we report on the micro- and nanostructure of the calcium phosphate coating produced by pulsed laser deposition (PLD), using focused ion beam (FIB) lamella sample preparation and transmission electron microscopy (TEM) as the characterization technique. The initial selected area electron diffraction (SAED) data demonstrated the presence of hydroxyapatite (HA) over any other possible calcium phosphate crystalline structure and the polycrystalline nature of the coating. Moreover, the SAED analyses showed clear textured ring patterns coherent with the presence of a preferred orientation in the HA nano-crystal growth. The SAED data also indicated that the coating appears to be textured in the 〈002〉 crystalline direction. Dark-field images obtained using 002 as the working reflection showed a clear oriented crystal growth in columns, from bottom to top. These columns have a peculiar arrangement of nano-crystals since, in some cases, the preferred orientation appears to start at a certain distance from the substrate. Direct d-spacing measurements on high-resolution TEM images provided further proof of the presence of an HA nano-crystal structure. The reported data may be of interest in the future to adjust the microstructure of the HA coatings. - Highlights: •The FIB lift-out technique allows a very site-specific sample preparation method for HRTEM analysis. •It also permits a fast assessment of the HA coating thickness and elemental composition (EDS). •The coatings exhibit a nano-crystalline nature, with a texturing effect along the 002 planes. •PLD is suitable for the production of crystalline c-axis oriented hydroxyapatite coatings. •The crystalline HA phase in the PLD coating is very similar to the present in bone.

  5. Revealing the nanostructure of calcium phosphate coatings using HRTEM/FIB techniques

    Energy Technology Data Exchange (ETDEWEB)

    Solla, E.L., E-mail: esolla@uvigo.es [Servicio de Microscopía Electrónica, CACTI, University of Vigo, Campus As Lagoas-Marcosende, 36310 Vigo (Spain); Rodríguez-González, B. [Servicio de Microscopía Electrónica, CACTI, University of Vigo, Campus As Lagoas-Marcosende, 36310 Vigo (Spain); Aguiar, H.; Rodríguez-Valencia, C.; Serra, J.; González, P. [Applied Physics Department, School of Industrial Engineering, University of Vigo, Campus As Lagoas-Marcosende, 36310 Vigo (Spain)

    2016-12-15

    Herein, we report on the micro- and nanostructure of the calcium phosphate coating produced by pulsed laser deposition (PLD), using focused ion beam (FIB) lamella sample preparation and transmission electron microscopy (TEM) as the characterization technique. The initial selected area electron diffraction (SAED) data demonstrated the presence of hydroxyapatite (HA) over any other possible calcium phosphate crystalline structure and the polycrystalline nature of the coating. Moreover, the SAED analyses showed clear textured ring patterns coherent with the presence of a preferred orientation in the HA nano-crystal growth. The SAED data also indicated that the coating appears to be textured in the 〈002〉 crystalline direction. Dark-field images obtained using 002 as the working reflection showed a clear oriented crystal growth in columns, from bottom to top. These columns have a peculiar arrangement of nano-crystals since, in some cases, the preferred orientation appears to start at a certain distance from the substrate. Direct d-spacing measurements on high-resolution TEM images provided further proof of the presence of an HA nano-crystal structure. The reported data may be of interest in the future to adjust the microstructure of the HA coatings. - Highlights: •The FIB lift-out technique allows a very site-specific sample preparation method for HRTEM analysis. •It also permits a fast assessment of the HA coating thickness and elemental composition (EDS). •The coatings exhibit a nano-crystalline nature, with a texturing effect along the 002 planes. •PLD is suitable for the production of crystalline c-axis oriented hydroxyapatite coatings. •The crystalline HA phase in the PLD coating is very similar to the present in bone.

  6. Atomic scale insight into the amorphous structure of Cu doped GeTe phase-change material

    International Nuclear Information System (INIS)

    Zhang, Linchuan; Sa, Baisheng; Zhou, Jian; Sun, Zhimei; Song, Zhitang

    2014-01-01

    GeTe shows promising application as a recording material for phase-change nonvolatile memory due to its fast crystallization speed and extraordinary amorphous stability. To further improve the performance of GeTe, various transition metals, such as copper, have been doped in GeTe in recent works. However, the effect of the doped transition metals on the stability of amorphous GeTe is not known. Here, we shed light on this problem for the system of Cu doped GeTe by means of ab initio molecular dynamics calculations. Our results show that the doped Cu atoms tend to agglomerate in amorphous GeTe. Further, base on analyzing the pair correlation functions, coordination numbers and bond angle distributions, remarkable changes in the local structure of amorphous GeTe induced by Cu are obviously seen. The present work may provide some clues for understanding the effect of early transition metals on the local structure of amorphous phase-change compounds, and hence should be helpful for optimizing the structure and performance of phase-change materials by doping transition metals.

  7. Peptide insertion, positioning, and stabilization in a membrane: insight from an all-atom molecular dynamics simulation.

    Science.gov (United States)

    Babakhani, Arneh; Gorfe, Alemayehu A; Gullingsrud, Justin; Kim, Judy E; Andrew McCammon, J

    Peptide insertion, positioning, and stabilization in a model membrane are probed via an all-atom molecular dynamics (MD) simulation. One peptide (WL5) is simulated in each leaflet of a solvated dimyristoylglycero-3-phosphate (DMPC) membrane. Within the first 5 ns, the peptides spontaneously insert into the membrane and then stabilize during the remaining 70 ns of simulation time. In both leaflets, the peptides localize to the membrane interface, and this localization is attributed to the formation of peptide-lipid hydrogen bonds. We show that the single tryptophan residue in each peptide contributes significantly to these hydrogen bonds; specifically, the nitrogen heteroatom of the indole ring plays a critical role. The tilt angles of the indole rings relative to the membrane normal in the upper and lower leaflets are approximately 26 degrees and 54 degrees , respectively. The tilt angles of the entire peptide chain are 62 degrees and 74 degrees . The membrane induces conformations of the peptide that are characteristic of beta-sheets, and the peptide enhances the lipid ordering in the membrane. Finally, the diffusion rate of the peptides in the membrane plane is calculated (based on experimental peptide concentrations) to be approximately 6 A(2)/ns, thus suggesting a 500 ns time scale for intermolecular interactions.

  8. Unveiling the chemical and morphological features of Sb:SnO2 nanocrystals by the combined use of HRTEM and Ab Initio surface energy calculations

    International Nuclear Information System (INIS)

    Stroppa, Daniel G.; Montoro, Luciano A.; Ramirez, Antonio J.; Beltran, Armando; Andres, Juan; Conti, Tiago G.; Silva, Rafael O. da; Longo, Elson; Leite, Edson R.

    2009-01-01

    Modeling of nanocrystals supported by advanced morphological and chemical characterization is a unique tool for the development of reliable nanostructured devices, which depends on the ability to synthesize and characterize material on the atomic scale. Among the most significant challenges in nanostructural characterization is the evaluation of crystal growth mechanisms and their dependence on the shape of nanoparticles and the distribution of doping elements. This work presents a new strategy to characterize nanocrystals, applied here to antimony-doped tin oxide (Sb-SnO 2 ) (ATO) by the combined use of experimental and simulated high-resolution transmission electron microscopy (HRTEM) images and surface energy ab initio calculations. The results show that the Wulff construction can not only describe the shape of nanocrystals as a function of surface energy distribution but also retrieve quantitative information on dopant distribution by the dimensional analysis of nanoparticle shapes. In addition, a novel three-dimensional evaluation of an oriented attachment growth mechanism is provided in the proposed methodology. This procedure is a useful approach for faceted nanocrystal shape modeling and indirect quantitative evaluation of dopant spatial distribution, which are difficult to evaluate by other techniques. (author)

  9. HRTEM analysis on nanocrystalline BaTiO3 and PbTiO3: size effects on ferroelectric phase transition temperature

    International Nuclear Information System (INIS)

    Bursill, L.A.; Jiang, B.; Peng, J.L.; Zhong, W.L.; Zhang, P.L.

    1997-01-01

    High-Resolution Transmission Electron Microscopic studies of nanocrystaline particles of BaTiO 3 and PbTiO 3 are reported. There are characteristic differences observed for BaTiO 3 prepared using sol gel (SG) and steric acid gel (SAG) methods. The former exhibit a critical size below which there is no paraelectric/ferroelectric phase transition, whereas BaTiO 3 prepared via the SAG route remained cubic for all conditions. The SAG preparations always showed chemical intergrowth defects whereas the SG preparations were single phase. Atomic resolution images of both varieties showed interesting surface steps and surface relaxations/reconstructions of some facets. Nanocrystalline PbTiO 3 prepared by the SG route remains tetragonal, albeit with decreasing c/a ratio, down to 25nm diameter. HRTEM observations of nanocrystalline PbTiO 3 are also presented. X-ray diffraction, dielectric and Raman scattering measurements also demonstrate pronounced size effects. The relationship between the observed nanostructures and size effects on the physical properties is discussed. 6 refs., 1 tab., 6 figs

  10. Novel insights into pericarp, protein body globoids of aleurone layer, starchy granules of three cereals gained using atomic force microscopy and environmental scanning electronic microscopy.

    Science.gov (United States)

    Antonini, Elena; Zara, Carolina; Valentini, Laura; Gobbi, Pietro; Ninfali, Paolino; Menotta, Michele

    2018-02-05

    In this study, we applied Environmental Scanning Electron Microscopy-Energy Dispersive Spectroscopy (ESEM-EDS) and Atomic Force Microscopy (AFM) analysis to three different cereal caryopses: barley, oat and einkorn wheat. The morphological structures, chemical elemental composition and surface characteristics of the three cereals were described. Regarding the morphology, barley showed the thickest pericarp, providing a strong barrier digestion and absorption of nutrients. The aleurone layer of each cereal type contained protein body globoids within its cells. Large type-A and small type-B starchy granules were revealed in the endosperm of barley and einkorn wheat, whereas irregular starchy granules were found in oats. The starchy granule elemental composition, detected by ESEM-EDS, was rather homogenous in the three cereals, whereas the pericarp and protein body globoids showed heterogeneity. In the protein body globoids, oats showed higher P and K concentrations than barley and einkorn wheat. Regarding the topographic profiles, detected by AFM, einkorn wheat starchy granules showed a surface profile that differed significantly from that of oats and barley, which were quite similar to one another. The present work provides insights into the morphological and chemical makeup of the three grains shedding light on the higher bio-accessibility of einkorn wheat nutrients compared to barley and oats, providing important suggestions for human nutrition and technological standpoints.

  11. Atomic scale insights into electrochemical versus gas phase oxidation of HCl over RuO2-based catalysts: A comparative review

    International Nuclear Information System (INIS)

    Over, Herbert

    2013-01-01

    In this article our current understanding of the electro-catalyzed chlorine evolution reaction (CER) in comparison with that of the heterogeneously-catalyzed gas phase oxidation of HCl (Deacon process: heterogeneous catalysis) over RuO 2 -based catalysts will be reviewed. Both types of harsh reactions are chemically similar: The main concern is catalyst stability, and in both cases the best catalyst contains RuO 2 as the catalytically active component so that a critical comparison may provide new insights into the underlying physicochemical processes. It is the primary scope of this review addresses atomic scale information on the RuO 2 -catalyzed HCl oxidation reaction either in electrochemical or in gas phase environment. In particular, the involved reaction mechanisms and the reason for the extraordinary stability of RuO 2 under such harsh reaction conditions will be discussed, emphasizing similarities and differences in the Deacon process and the CER and what can be learnt from this comparison. The distinct properties of RuO 2 , which are responsible for its extraordinary catalytic performance in both the CER and the Deacon process, are highlighted

  12. Novel insights into pericarp, protein body globoids of aleurone layer, starchy granules of three cereals gained using atomic force microscopy and environmental scanning electronic microscopy

    Science.gov (United States)

    Antonini, Elena; Zara, Carolina; Valentini, Laura; Gobbi, Pietro; Menotta, Michele

    2018-01-01

    In this study, we applied Environmental Scanning Electron Microscopy-Energy Dispersive Spectroscopy (ESEM-EDS) and Atomic Force Microscopy (AFM) analysis to three different cereal caryopses: barley, oat and einkorn wheat. The morphological structures, chemical elemental composition and surface characteristics of the three cereals were described. Regarding the morphology, barley showed the thickest pericarp, providing a strong barrier to digestion and absorption of nutrients. The aleurone layer of each cereal type contained protein body globoids within its cells. Large type-A and small type-B starchy granules were revealed in the endosperm of barley and einkorn wheat, whereas irregular starchy granules were found in oats. The starchy granule elemental composition, detected by ESEM-EDS, was rather homogenous in the three cereals, whereas the pericarp and protein body globoids showed heterogeneity. In the protein body globoids, oats showed higher P and K concentrations than barley and einkorn wheat. Regarding the topographic profiles, detected by AFM, einkorn wheat starchy granules showed a surface profile that differed significantly from that of oats and barley, which were quite similar to one another. The present work provides insights into the morphological and chemical makeup of the three grains shedding light on the higher bio-accessibility of einkorn wheat nutrients compared to barley and oats, providing important suggestions for human nutrition and technological standpoints. PMID:29569870

  13. Quantitative High Resolution Transmission Electron Microscopy (HRTEM): a novel approach towards application oriented basic research

    International Nuclear Information System (INIS)

    Kisielowski, Christian; Weber, Eicke R.; Liliental-Weber, Zuzanna

    1996-01-01

    This paper reviews recent developments of microscopic methods that base on a quantitative analysis of electron micrographs to access subsurface systems at the atomic scale. It focuses on non-equilibrium diffusion processes that are observed in nano structured MBE grown materials if a low growth temperature was used and on local deviations from a stoichiometric composition of materials. As examples we investigate Ga As/Al As and Si/Ge Si heterostructures and Ga N single crystals. The purpose of the research is twofold. On the one hand it helps understanding physical processes at the atomic scale. On the other hand we can use the results to link basic physical knowledge with the performance of semiconductor devices made from nano structured materials. (author). 28 refs., 15 figs

  14. Diagenetic Microcrystalline Opal Varieties from the Monterey Formation, CA: HRTEM Study of Structures and Phase Transformation Mechanisms

    Science.gov (United States)

    Cady, Sherry L.; Wenk, H.-R.; DeVincenzi, Don (Technical Monitor)

    1994-01-01

    Microcrystalline opal varieties form as intermediary precipitates during the diagenetic transformation of biogenically precipitated non-crystalline opal (opal-A) to microquartz. With regard to the Monterey Formation of California, X-ray powder diffraction studies have shown that a decrease in the primary d-spacing of opal-CT toward that of cristobalite occurs with increasing diagenesis. The initial timing of opal-CT/quartz formation and the value of the primary opal-CT d-spacing, are influenced by the sediment. lithology. Transmission electron microscopy methods (CTEM/HRTEM) were used to investigate the structure of the diagenetic phases and establish transformation mechanisms between the varieties of microcrystalline opals in charts and porcelanites from the Monterey Formation. HRTEM images revealed that the most common fibrous varieties of microcrystalline opals contain varying amounts of structural disorder. Finite lamellar units of cristobalite-and tridymite-type. layer sequences were found to be randomly stacked in a direction perpendicular to the fiber axis. Disordered and ordered fibers were found to have coprecipitated within the same radial fiber bundles that formed within the matrix of the Most siliceous samples. HRTEM images, which reveal that the fibers within radial and lepispheric fiber bundles branch non-crystallographically, support an earlier proposal that microspheres in chert grow via a spherulitic growth mechanism. A less common variety of opal-CT was found to be characterized by non-parallel (low-angle) stacking sequences that often contain twinned lamellae. Tabular-shaped crystals of orthorhombic tridymite (PO-2) were also identified in the porcelanite samples. A shift in the primary d-spacing of opal-CT has been interpreted as an indication of solid-state ordering g toward a predominantly cristobalite structure, (opal-C). Domains of opal-C were identified as topotactically-oriented overgrowths on discrete Sections of opal-CT fibers and as

  15. AFM, XRD and HRTEM Studies of Annealed FePd Thin Films

    International Nuclear Information System (INIS)

    Perzanowski, M.; Zabila, Y.; Polit, A.; Krupinski, M.; Dobrowolska, A.; Marszalek, M.; Morgiel, J.

    2010-01-01

    Ferromagnetic FePd L1 0 ordered alloys are highly expected as forthcoming high-density recording materials, because they reveal a large perpendicular magnetocrystalline anisotropy. The value of the magnetic anisotropy of FePd alloy strongly depends on the alloy composition, degree of alloy order as well as on the crystallographic grain orientation. In particular, to obtain the perpendicular anisotropy, it is necessary to get the films with (001) texture. One of the successful methods, which allows one to obtain highly ordered alloy, is a subsequent deposition of Fe and Pd layers, followed by an annealing at high temperature. This paper presents the study of the FePd thin alloy film structure changing in the result of high temperature annealing. During the annealing in high vacuum, the measurements of electrical resistance were performed, indicating the regions of different structure evolution. Changes in the crystal structure and surface morphology induced by thermal treatment were investigated by X-ray diffraction, atomic force microscopy, as well as high resolution transmission electron microscopy and then compared with electrical resistivity measurement. The slow thermal annealing of the deposited layers leads to the formation of L1 0 ordered FePd alloy with preferred (111) grain orientation. After the annealing at the highest used temperature, the dewetting process was observed, resulting in a creation of well oriented, regular nanoparticles. (author)

  16. On the benefit of the negative-spherical-aberration imaging technique for quantitative HRTEM

    International Nuclear Information System (INIS)

    Jia, C.L.; Houben, L.; Thust, A.; Barthel, J.

    2010-01-01

    Employing an aberration corrector in a high-resolution transmission electron microscope, the spherical aberration C S can be tuned to negative values, resulting in a novel imaging technique, which is called the negative C S imaging (NCSI) technique. The image contrast obtained with the NCSI technique is compared quantitatively with the image contrast formed with the traditional positive C S imaging (PCSI) technique. For the case of thin objects negative C S images are superior to positive C S images concerning the magnitude of the obtained contrast, which is due to constructive rather than destructive superposition of fundamental contrast contributions. As a consequence, the image signal obtained with a negative spherical aberration is significantly more robust against noise caused by amorphous surface layers, resulting in a measurement precision of atomic positions which is by a factor of 2-3 better at an identical noise level. The quantitative comparison of the two alternative C S -corrected imaging modes shows that the NCSI mode yields significantly more precise results in quantitative high-resolution transmission electron microscopy of thin objects than the traditional PCSI mode.

  17. Optimization of exit-plane waves restored from HRTEM through-focal series

    International Nuclear Information System (INIS)

    Erni, Rolf; Rossell, Marta D.; Nakashima, Philip N.H.

    2010-01-01

    Atomic-resolution transmission electron microscopy has largely benefited from the implementation of aberration correctors in the imaging part of the microscope. Though the dominant geometrical axial aberrations can in principle be corrected or suitably adjusted, the impact of higher-order aberrations, which are mainly due to the implementation of non-round electron optical elements, on the imaging process remains unclear. Based on a semi-empirical criterion, we analyze the impact of residual aperture aberrations on the quality of exit-plane waves that are retrieved from through-focal series recorded using an aberration-corrected and monochromated instrument which was operated at 300 kV and enabled for an information transfer of ∼0.05 nm. We show that the impact of some of the higher-order aberrations in retrieved exit-plane waves can be balanced by a suitable adjustment of symmetry equivalent lower-order aberrations. We find that proper compensation and correction of 1st and 2nd order aberrations is critical, and that the required accuracy is difficult to achieve. This results in an apparent insensitivity towards residual higher-order aberrations. We also investigate the influence of the detector characteristics on the image contrast. We find that correction for the modulation transfer function results in a contrast gain of up to 40%.

  18. Quasi-atoms

    International Nuclear Information System (INIS)

    Armbruster, P.

    1976-01-01

    The concept of a quasi-atom is discussed, and several experiments are described in which molecular or quasi-atomic transitions have been observed. X-ray spectra are shown for these experiments in which heavy ion projectiles were incident on various targets and the resultant combined system behaved as a quasi-atom. This rapidly developing field has already given new insight into atomic collision phenomena. (P.J.S.)

  19. DSC and HRTEM investigation of the precipitates in Al-1.0%Mg{sub 2} Si-0.5%Ag alloy

    Energy Technology Data Exchange (ETDEWEB)

    Gaber, A.; Ali, A.M.; Zou, Y. [Toyama University (Japan). Venture Business Laboratory; Matsuda, K.; Ikeno, S. [Toyama University (Japan). Faculty of Engineering

    2004-12-15

    The understanding and control of nanoscale precipitation in an Al-1.0 wt-%Mg{sub 2} Si-0.5 wt-% Ag alloy during artificial aging is critical for achieving optimum mechanical properties. To achieve this objective, both differential scanning calorimetry (DSC) and high resolution transmission electron microscopy (HRTEM) have been utilised. The non-isothermal DSC thermograms exhibited eight reaction peaks; six are exothermic (precipitation) and two are endothermic (dissolution) reactions. The activation energies associated with the individual precipitates are determined. With the aid of HRTEM, the evolved precipitates have been characterised. (author)

  20. Microstructure imaging of the YBCO thin film/MgO substrate interface: HRTEM and Fourier analysis of the Moire fringe pattern

    International Nuclear Information System (INIS)

    Auzary, S.; Pailloux, F.; Denanot, M.F.; Gaboriaud, R.J.

    1998-01-01

    Detailed microstructural aspects of the interface between YBaCuO thin films and MgO substrate are studied by means of a Fourier analysis of Moire fringe pattern obtained from HRTEM investigations of plan view samples. The main features of the observations are large, well oriented crystallographic domains surrounded by wide boundaries. HRTEM investigations together with the Fourier analysis show evidence of both orthorhombic and pseudo-tetragonal structure in the YBaCuO film. An accommodation mechanism is suggested from the Fourier analysis of the Moire fringe pattern. (orig.)

  1. Formic acid decomposition on Pt1/Cu (111) single platinum atom catalyst: Insights from DFT calculations and energetic span model analysis

    Science.gov (United States)

    Wang, Ying-Fan; Li, Kun; Wang, Gui-Chang

    2018-04-01

    Inspired by the recent surface experimental results that the monatomic Pt catalysts has more excellent hydrogen production that Cu(111) surface, the mechanism of decomposition of formic acid on Cu(111) and single atom Pt1/Cu(111) surface was studied by periodic density functional theory calculations in the present work. The results show that the formic acid tends to undergo dehydrogenation on both surfaces to obtain the hydrogen product of the target product, and the selectivity and catalytic activity of Pt1/Cu (111) surface for formic acid dehydrogenation are better. The reason is that the single atom Pt1/Cu(111) catalyst reduces the reaction energy barrier (i.e., HCOO → CO2 + H) of the critical step of the dehydrogenation reaction due to the fact that the single atom Pt1/Cu(111) catalyst binds formate weakly compared to that of Cu (111) one. Moreover, it was found that the Pt1/Cu (111) binds CO more strongly than that of Cu (111) one and thus leading to the difficult for the formation of CO. These two factors would make the single Pt atom catalyst had the high selectivity for the H2 production. It is hoped that the present work may help people to design the efficient H2 production from HCOOH decomposition by reduce the surface binding strength of HCOO species, for example, using the low coordination number active site like single atom or other related catalytic system.

  2. Practical aspects of the use of the X(2) holder for HRTEM-quality TEM sample preparation by FIB.

    Science.gov (United States)

    van Mierlo, Willem; Geiger, Dorin; Robins, Alan; Stumpf, Matthias; Ray, Mary Louise; Fischione, Paul; Kaiser, Ute

    2014-12-01

    The X(2) holder enables the effective production of thin, electron transparent samples for high-resolution transmission electron microscopy (HRTEM). Improvements to the X(2) holder for high-quality transmission electron microscopy (TEM) sample preparation are presented in this paper. We discuss the influence of backscattered electrons (BSE) from the sample holder in determining the lamella thickness in situ and demonstrate that a significant improvement in thickness determination can be achieved by comparatively simple means using the relative BSE intensity. We show (using Monte Carlo simulations) that by taking into account the finite collection angle of the electron backscatter detector, an approximately 20% underestimation of the lamella thickness in a silicon sample can be avoided. However, a correct thickness determination for light-element lamellas still remains a problem with the backscatter method; we introduce a more accurate method using the energy dispersive X-ray spectroscopy (EDX) signal for in situ thickness determination. Finally, we demonstrate how to produce a thin lamella with a nearly damage-free surface using the X(2) holder in combination with sub-kV polishing in the Fischione Instruments׳ NanoMill(®) TEM specimen preparation system. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Insights into thermal diffusion of germanium and oxygen atoms in HfO2/GeO2/Ge gate stacks and their suppressed reaction with atomically thin AlOx interlayers

    International Nuclear Information System (INIS)

    Ogawa, Shingo; Asahara, Ryohei; Minoura, Yuya; Hosoi, Takuji; Shimura, Takayoshi; Watanabe, Heiji; Sako, Hideki; Kawasaki, Naohiko; Yamada, Ichiko; Miyamoto, Takashi

    2015-01-01

    The thermal diffusion of germanium and oxygen atoms in HfO 2 /GeO 2 /Ge gate stacks was comprehensively evaluated by x-ray photoelectron spectroscopy and secondary ion mass spectrometry combined with an isotopic labeling technique. It was found that 18 O-tracers composing the GeO 2 underlayers diffuse within the HfO 2 overlayers based on Fick's law with the low activation energy of about 0.5 eV. Although out-diffusion of the germanium atoms through HfO 2 also proceeded at the low temperatures of around 200 °C, the diffusing germanium atoms preferentially segregated on the HfO 2 surfaces, and the reaction was further enhanced at high temperatures with the assistance of GeO desorption. A technique to insert atomically thin AlO x interlayers between the HfO 2 and GeO 2 layers was proven to effectively suppress both of these independent germanium and oxygen intermixing reactions in the gate stacks

  4. Insights into thermal diffusion of germanium and oxygen atoms in HfO{sub 2}/GeO{sub 2}/Ge gate stacks and their suppressed reaction with atomically thin AlO{sub x} interlayers

    Energy Technology Data Exchange (ETDEWEB)

    Ogawa, Shingo, E-mail: Shingo-Ogawa@trc.toray.co.jp [Toray Research Center, Inc., 3-3-7 Sonoyama, Otsu, Shiga 520-8567 (Japan); Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan); Asahara, Ryohei; Minoura, Yuya; Hosoi, Takuji, E-mail: hosoi@mls.eng.osaka-u.ac.jp; Shimura, Takayoshi; Watanabe, Heiji [Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan); Sako, Hideki; Kawasaki, Naohiko; Yamada, Ichiko; Miyamoto, Takashi [Toray Research Center, Inc., 3-3-7 Sonoyama, Otsu, Shiga 520-8567 (Japan)

    2015-12-21

    The thermal diffusion of germanium and oxygen atoms in HfO{sub 2}/GeO{sub 2}/Ge gate stacks was comprehensively evaluated by x-ray photoelectron spectroscopy and secondary ion mass spectrometry combined with an isotopic labeling technique. It was found that {sup 18}O-tracers composing the GeO{sub 2} underlayers diffuse within the HfO{sub 2} overlayers based on Fick's law with the low activation energy of about 0.5 eV. Although out-diffusion of the germanium atoms through HfO{sub 2} also proceeded at the low temperatures of around 200 °C, the diffusing germanium atoms preferentially segregated on the HfO{sub 2} surfaces, and the reaction was further enhanced at high temperatures with the assistance of GeO desorption. A technique to insert atomically thin AlO{sub x} interlayers between the HfO{sub 2} and GeO{sub 2} layers was proven to effectively suppress both of these independent germanium and oxygen intermixing reactions in the gate stacks.

  5. Caracterización mediante HRTEM de un acero AISI4140 nitrurado por postdescarga micro-ondas

    Directory of Open Access Journals (Sweden)

    Béjar-Gómez, L.

    2005-12-01

    Full Text Available An analysis of the nitrides formed in an AISI 4140 steel nitrided by postdischarge microwave nitriding treatment was carried out by high resolution transmission electron microscopy (HRTEM, fast Fourier transform (FFT and nanoanalysis. The steel samples were nitrided below of the eutectoid transformation point (590 °C, after nitriding the samples were cooling slowly inside in the reactor whit an argon atmosphere. The analysis were carried out in a FEG-TEM PHILIPS TECNAI F20 at 200 Kv. The results showed the morphology and size of the nitrides ε-Fe2-3N and γ’-Fe4N, which had coherency whit the matrix. By other hand the following crystallographic relations were determined: (110 Fe-α ║ (1001 ε-Fe2-3N ║ (110 γ’-Fe4N and [1-1 0]Fe-α ║ [1 0-1 0] ε-Fe2-3N ║ [0 1 1] Fe4N.

    Un análisis de las fases de nitruros formados en un acero AISI 4140, nitrurado mediante condiciones de postdescarga micro-ondas, se llevó a cabo por microscopía electrónica de transmisión de alta resolución (HRTEM, rápida transformada de Fourier (FFT y nanoanálisis. Las muestras de acero fueron nitruradas por debajo del punto de transformación eutectoide (590 °C; después del tratamiento de nitruración las piezas fueron enfriadas lentamente dentro del reactor con una atmósfera de argón. Los análisis se realizaron en un microscopio Philips con cañón de emisión de campo Tecnai F20 a 200 Kv (PHILIPS FEG-TEM TECNAI F20. Los resultados mostraron la morfología y tamaño de los nitruros de hierro ε-Fe2-3N y γ’-Fe4N, los cuáles mostraron coherencia con la matriz. Además, se obtuvo la siguiente relación de coherencia entre precipitados y matriz: (110 Fe-α ║ (1001 ε-Fe2-3N ║ (110 γ’-Fe4N y [1-1 0]Fe-α ║ [1 0-1 0] ε-Fe2-3N ║ [0 1 1] Fe4N.

  6. Mechanism of uranium(VI) uptake by Saccharomyces cerevisiae under environmentally relevant conditions: Batch, HRTEM, and FTIR studies

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Xia, E-mail: lux2009@lzu.edu.cn; Zhou, Xiao-jiao; Wang, Tie-shan, E-mail: tswang@lzu.edu.cn

    2013-11-15

    Highlights: • Equilibrium reaches very rapid within 15 min. • pH shift towards neutral indicates release of hydroxyl ions. • High ionic strength inhabits biosorption capacity. • Uptake capacity of heat-killed cells is an order of magnitude higher than live one. • Electrostatic interaction, precipitation, and complexation are the main mechanisms. -- Abstract: Biosorption is of significance for the safety evaluation of high-level nuclear wastes repositories and remediation of radioactive contamination places. Quantitive study and structural characterization of uranium uptake by both live and heat-killed Saccharomyces cerevisiae at environmentally relevant uranium concentration and with different ionic strengths were carried out. Kinetic investigation showed the equilibrium reached within 15 min. In equilibrium studies, pH shift towards neutral indicated release of hydroxyl ions. pH was the most important factor, which partly affected electrostatic interaction between uranyl ions and S. cerevisiae surface. The high ionic strength inhibited biosorption capacity, which can be explained by a competitive reaction between sodium ions and uranyl ions. Heat killing process significantly enhanced biosorption capacity, showing an order of magnitude higher than that of live cells. High resolution transmission electron microscopy (HRTEM) coupled with energy dispersive X-ray (EDX) showed needle-like uranium-phosphate precipitation formed on the cell walls for both live and heat-killed cells. Besides, dark-field micrographs displayed considerable similar uranium-phosphate precipitation presented outside the heat-killed cells. The phosphate released during heat-killing process. FTIR illustrated function groups hydroxyl, carboxyl, phosphate, and amino groups played important role in complexation with uranium.

  7. XRD and HRTEM characterization of mechanosynthesized Ti{sub 0.9}W{sub 0.1}C cermet

    Energy Technology Data Exchange (ETDEWEB)

    Bandyopadhyay, S. [Department of Physics, The University of Burdwan, Golapbag, Burdwan 713104, West Bengal (India); Dutta, H. [Department of Physics, Vivekananda College, Burdwan 713103, West Bengal (India); Pradhan, S.K., E-mail: skp_bu@yahoo.com [Department of Physics, The University of Burdwan, Golapbag, Burdwan 713104, West Bengal (India)

    2013-12-25

    Highlights: •Cubic Ti{sub 0.9}W{sub 0.1}C is formed after 50 min of milling of α-Ti, W and graphite powders. •Nanocrystalline Ti{sub 0.9}W{sub 0.1}C with particle size ∼11 nm is obtained after 8 h milling. •Average particle size of Ti{sub 0.9}W{sub 0.1}C from XRD analysis and HRTEM is very close. •Formation of Ti{sub 0.9}W{sub 0.1}C is hindered as compared with TiC. -- Abstract: Elemental powder mixture of titanium, tungsten and graphite is milled by high energy planetary ball mill at a fixed ball to powder mass ratio (BPMR) for different duration to produce nanosized particles of Ti{sub 0.9}W{sub 0.1}C hard metal. Microstructure characterization in terms of lattice imperfections and phase quantification of ball-milled samples has been done primarily by analyzing the XRD pattern and employing Rietveld method of structure and microstructure refinement. After 8 h of ball-milling full formation of Ti{sub 0.9}W{sub 0.1}C is noticed without any contamination of other phase or milling media. TEM study of 8 h ball-milled sample gives direct supportive evidence of structural and microstructural evaluation by XRD pattern analysis. A comparative study of microstructural changes between TiC and Ti{sub 0.9}W{sub 0.1}C helps to understand the effect of addition of W as solute in Ti–C metal matrix.

  8. HR-TEM and FT-Raman dataset of the caffeine interacted Phe–Phe peptide nanotube for possible sensing applications

    Directory of Open Access Journals (Sweden)

    A. Lakshmi Narayanan

    2018-02-01

    Full Text Available Sensing ability of caffeine interaction with Phe-Phe annotates (PNTs, is presented (Govindhan et al., 2017; Karthikeyan et al., 2014; Tavagnacco et al., 2013; Kennedy et al., 2011; Wang et al., 2017 [1–5] in this data set. Investigation of synthesized caffeine carrying peptide nanotubes are carried out by FT-Raman spectral analysis and high resolution transmission electron microscopy (HR-TEM. Particle size of the caffeine loaded PNTs is < 40 nm. The FT-Raman spectrum signals are enhanced in the region of 400–1700 cm−1. These data are ideal tool for the applications like biosensing and drug delivery research (DDS. Keywords: Caffeine, PNTs, Sensing, HR-TEM, FT-Raman data

  9. Further Insight into the Lability of MeCN Ligands of Cytotoxic Cycloruthenated Compounds: Evidence for the Antisymbiotic Effect Trans to the Carbon Atom at the Ru Center.

    Science.gov (United States)

    Barbosa, Ana Soraya Lima; Werlé, Christophe; Colunga, Claudia Olivia Oliva; Rodríguez, Cecilia Franco; Toscano, Ruben Alfredo; Le Lagadec, Ronan; Pfeffer, Michel

    2015-08-03

    The two MeCN ligands in [Ru(2-C6H4-2'-Py-κC,N)(Phen, trans-C)(MeCN)2]PF6 (1), both trans to a sp(2) hybridized N atom, cannot be substituted by any other ligand. In contrast, the isomerized derivative [Ru(2-C6H4-2'-Py-κC,N)(Phen, cis-C)(MeCN)2]PF6 (2), in which one MeCN ligand is now trans to the C atom of the phenyl ring orthometalated to Ru, leads to fast and quantitative substitution reactions with several monodentate ligands. With PPh3, 2 affords [Ru(2-C6H4-2'-Py-κC,N)(Phen, cis-C)(PPh3)(MeCN)]PF6 (3), in which PPh3 is trans to the C σ bound to Ru. Compound 3 is not kinetically stable, because, under thermodynamic control, it leads to 4, in which the PPh3 is trans to a N atom of the Phen ligand. Dimethylsulfoxide (DMSO) can also substitute a MeCN ligand in 2, leading to 5, in which DMSO is coordinated to Ru via its S atom trans to the N atom of the Phen ligand, the isomer under thermodynamic control being the only compound observed. We also found evidence for the fast to very fast substitution of MeCN in 2 by water or a chloride anion by studying the electronic spectra of 2 in the presence of water or NBu4Cl, respectively. An isomerization related to that observed between 3 and 4 is also found for the known monophosphine derivative [Ru(2-C6H4-2'-Py-κC,N)(PPh3, trans-C)(MeCN)3]PF6 (10), in which the PPh3 is located trans to the C of the cyclometalated 2-phenylpyridine, since, upon treatment by refluxing MeCN, it leads to its isomer 11, [Ru(2-C6H4-2'-Py-κC,N)(PPh3, cis-C)(MeCN)3]PF6. Further substitutions are also observed on 11, whereby N^N chelates (N^N = 2,2'-bipyridine and phenanthroline) substitute two MeCN ligands, affording [Ru(2-C6H4-2'-Py-κC,N)(PPh3, cis-C)(N^N)(MeCN)]PF6 (12a and 12b). Altogether, the behavior of the obtained complexes by ligand substitution reactions can be rationalized by an antisymbiotic effect on the Ru center, trans to the C atom of the cyclometalated unit, leading to compounds having the least nucleophilic ligand trans to C

  10. Insights inot the atomic many-particle dynamics of scattering processes by ab-initio calculations; Einblicke in die atomare Vielteilchendynamik von Streuprozessen durch ab-initio-Rechnungen

    Energy Technology Data Exchange (ETDEWEB)

    Zapukhlyak, Myroslav

    2008-12-05

    The present thesis gives a theoretical contribution to the understanding of the many-particle dynamics in inelastic ion-atom collisions. Many-electron dynamics in ion-helium collisions and proton-sodium collisions was theoretically studied. The description is based on the semiclassical approximation with the straight orbit for the projectile motion. The ion-atom collision problem is by this reduced to a time-dependent many-electron problem and in the non-relativistic approximation described by the time-dependent Schroedinger equation. The solution of the many-electron problem pursues in the framework of the time-dependent density functional theory. The time-dependent Schroedinger equation for the interacting many-electron problem is transformed to the system of the time-dependent Kohn-Sham equations and solved by the two-center-basis generator method. The unknown time-dependent exchange-correlation one-particle potential forces different approximation in the time-dependent Kohn-Shan scheme. In this thesis the model of the independent electrons was applied as basis model, in which the electron-electron correlation is consistently neglected in all parts and in all steps. Differential cross sections for different one- and two-electron processes were calculated in the so-called eikonal approximation for the collisional systems p-He, He{sup 2+}-He, and Ar{sup q+}-He (q=15-18). [German] Die vorliegende Arbeit leistet einen theoretischen Beitrag zum Verstaendnis der Vielteilchendynamik in inelastischen Ion-Atom-Stoessen. Vielelektronendynamik in Ion-Helium-Stoessen und Proton-Natrium-Stoessen wurde theoretisch untersucht. Die Beschreibung basiert auf der semiklassischen Naeherung mit der geraden Bahn fuer die Projektilbewegung. Das Ion-Atom- Stossproblem wird damit auf ein zeitabhaengiges Vielelektronenproblem reduziert und in der nichtrelativistischen Naeherung mit der zeitabhaengigen Schroedinger-Gleichung beschrieben. Die Loesung des Vielelektronenproblems erfolgt im

  11. Sub-Angstrom Atomic-Resolution Imaging of Heavy Atoms to Light Atoms

    Energy Technology Data Exchange (ETDEWEB)

    O' Keefe, Michael A.; Shao-Horn, Yang

    2003-05-23

    Three decades ago John Cowley and his group at ASU achieved high-resolution electron microscope images showing the crystal unit cell contents at better than 4Angstrom resolution. Over the years, this achievement has inspired improvements in resolution that have enabled researchers to pinpoint the positions of heavy atom columns within the cell. More recently, this ability has been extended to light atoms as resolution has improved. Sub-Angstrom resolution has enabled researchers to image the columns of light atoms (carbon, oxygen and nitrogen) that are present in many complex structures. By using sub-Angstrom focal-series reconstruction of the specimen exit surface wave to image columns of cobalt, oxygen, and lithium atoms in a transition metal oxide structure commonly used as positive electrodes in lithium rechargeable batteries, we show that the range of detectable light atoms extends to lithium. HRTEM at sub-Angstrom resolution will provide the essential role of experimental verification for the emergent nanotech revolution. Our results foreshadow those to be expected from next-generation TEMs with Cs-corrected lenses and monochromated electron beams.

  12. Davisson-Germer Prize in Atomic or Surface Physics: The COLTRIMS multi-particle imaging technique-new Insight into the World of Correlation

    Science.gov (United States)

    Schmidt-Bocking, Horst

    2008-05-01

    The correlated many-particle dynamics in Coulombic systems, which is one of the unsolved fundamental problems in AMO-physics, can now be experimentally approached with so far unprecedented completeness and precision. The recent development of the COLTRIMS technique (COLd Target Recoil Ion Momentum Spectroscopy) provides a coincident multi-fragment imaging technique for eV and sub-eV fragment detection. In its completeness it is as powerful as the bubble chamber in high energy physics. In recent benchmark experiments quasi snapshots (duration as short as an atto-sec) of the correlated dynamics between electrons and nuclei has been made for atomic and molecular objects. This new imaging technique has opened a powerful observation window into the hidden world of many-particle dynamics. Recent multiple-ionization studies will be presented and the observation of correlated electron pairs will be discussed.

  13. Atomic resolution imaging of ferroelectric domains

    International Nuclear Information System (INIS)

    Bursill, L.A.

    1997-01-01

    Electron optical principles involved in obtaining atomic resolution images of ferroelectric domains are reviewed, including the methods available to obtain meaningful interpretation and analysis of the image detail in terms of the atomic structures. Recent work is concerned with establishing the relationship between the essentially static chemical nanodomains and the spatial and temporal fluctuations of the nanoscale polar domains present in the relaxor class of materials, including lead scandium tantalate (PST) and lead magnesium niobate (PMN). Correct interpretation of the images required use of Next Nearest Neighbour Ising model simulations for the chemical domain textures upon which we must superimpose the polar domain textures; an introduction to this work is presented. A thorough analysis of the atomic scale chemical inhomogeneities, based upon the HRTEM results, has lead to an improved formulation of the theory of the dielectric response of PMN and PST, which is capable to predict the observed temperature and frequency dependence. HRTEM may be combined with solid state and statistical physics principles to provide a deeper understanding of structure/property relationships. 15 refs., 6 figs

  14. Mechanistic insights into dioxygen activation, oxygen atom exchange and substrate epoxidation by AsqJ dioxygenase from quantum mechanical/molecular mechanical calculations.

    Science.gov (United States)

    Song, Xudan; Lu, Jiarui; Lai, Wenzhen

    2017-08-02

    Herein, we use in-protein quantum mechanical/molecular mechanical (QM/MM) calculations to elucidate the mechanism of dioxygen activation, oxygen atom exchange and substrate epoxidation processes by AsqJ, an Fe II /α-ketoglutarate-dependent dioxygenase (α-KGD) using a 2-His-1-Asp facial triad. Our results demonstrated that the whole reaction proceeds through a quintet surface. The dioxygen activation by AsqJ leads to a quintet penta-coordinated Fe IV -oxo species, which has a square pyramidal geometry with the oxo group trans to His134. This penta-coordinated Fe IV -oxo species is not the reactive one in the substrate epoxidation reaction since its oxo group is pointing away from the target C[double bond, length as m-dash]C bond. Instead, it can undergo the oxo group isomerization followed by water binding or the water binding followed by oxygen atom exchange to form the reactive hexa-coordinated Fe IV -oxo species with the oxo group trans to His211. The calculated parameters of Mössbauer spectra for this hexa-coordinated Fe IV -oxo intermediate are in excellent agreement with the experimental values, suggesting that it is most likely the experimentally trapped species. The calculated energetics indicated that the rate-limiting step is the substrate C[double bond, length as m-dash]C bond activation. This work improves our understanding of the dioxygen activation by α-KGD and provides important structural information about the reactive Fe IV -oxo species.

  15. Material insights of HfO2-based integrated 1-transistor-1-resistor resistive random access memory devices processed by batch atomic layer deposition.

    Science.gov (United States)

    Niu, Gang; Kim, Hee-Dong; Roelofs, Robin; Perez, Eduardo; Schubert, Markus Andreas; Zaumseil, Peter; Costina, Ioan; Wenger, Christian

    2016-06-17

    With the continuous scaling of resistive random access memory (RRAM) devices, in-depth understanding of the physical mechanism and the material issues, particularly by directly studying integrated cells, become more and more important to further improve the device performances. In this work, HfO2-based integrated 1-transistor-1-resistor (1T1R) RRAM devices were processed in a standard 0.25 μm complementary-metal-oxide-semiconductor (CMOS) process line, using a batch atomic layer deposition (ALD) tool, which is particularly designed for mass production. We demonstrate a systematic study on TiN/Ti/HfO2/TiN/Si RRAM devices to correlate key material factors (nano-crystallites and carbon impurities) with the filament type resistive switching (RS) behaviours. The augmentation of the nano-crystallites density in the film increases the forming voltage of devices and its variation. Carbon residues in HfO2 films turn out to be an even more significant factor strongly impacting the RS behaviour. A relatively higher deposition temperature of 300 °C dramatically reduces the residual carbon concentration, thus leading to enhanced RS performances of devices, including lower power consumption, better endurance and higher reliability. Such thorough understanding on physical mechanism of RS and the correlation between material and device performances will facilitate the realization of high density and reliable embedded RRAM devices with low power consumption.

  16. HR-TEM and FT-Raman dataset of the caffeine interacted Phe-Phe peptide nanotube for possible sensing applications.

    Science.gov (United States)

    Narayanan, A Lakshmi; Dhamodaran, M; Solomon, J Samu; Karthikeyan, B; Govindhan, R

    2018-02-01

    Sensing ability of caffeine interaction with Phe-Phe annotates (PNTs), is presented (Govindhan et al., 2017; Karthikeyan et al., 2014; Tavagnacco et al., 2013; Kennedy et al., 2011; Wang et al., 2017) [1-5] in this data set. Investigation of synthesized caffeine carrying peptide nanotubes are carried out by FT-Raman spectral analysis and high resolution transmission electron microscopy (HR-TEM). Particle size of the caffeine loaded PNTs is < 40 nm. The FT-Raman spectrum signals are enhanced in the region of 400-1700 cm -1 . These data are ideal tool for the applications like biosensing and drug delivery research (DDS).

  17. HR-TEM and FT-Raman dataset of the caffeine interacted Phe–Phe peptide nanotube for possible sensing applications

    OpenAIRE

    Narayanan, A. Lakshmi; Dhamodaran, M.; Solomon, J. Samu; Karthikeyan, B.; Govindhan, R.

    2017-01-01

    Sensing ability of caffeine interaction with Phe-Phe annotates (PNTs), is presented (Govindhan et al., 2017; Karthikeyan et al., 2014; Tavagnacco et al., 2013; Kennedy et al., 2011; Wang et al., 2017) [1–5] in this data set. Investigation of synthesized caffeine carrying peptide nanotubes are carried out by FT-Raman spectral analysis and high resolution transmission electron microscopy (HR-TEM). Particle size of the caffeine loaded PNTs is < 40 nm. The FT-Raman spectrum signals are enhanced i...

  18. Atom optics

    International Nuclear Information System (INIS)

    Balykin, V. I.; Jhe, W.

    1999-01-01

    Atom optics, in analogy to neutron and electron optics, deals with the realization of as a traditional elements, such as lenes, mirrors, beam splitters and atom interferometers, as well as a new 'dissipative' elements such as a slower and a cooler, which have no analogy in an another types of optics. Atom optics made the development of atom interferometer with high sensitivity for measurement of acceleration and rotational possible. The practical interest in atom optics lies in the opportunities to create atom microprobe with atom-size resolution and minimum damage of investigated objects. (Cho, G. S.)

  19. Atom-by-atom assembly

    International Nuclear Information System (INIS)

    Hla, Saw Wai

    2014-01-01

    Atomic manipulation using a scanning tunneling microscope (STM) tip enables the construction of quantum structures on an atom-by-atom basis, as well as the investigation of the electronic and dynamical properties of individual atoms on a one-atom-at-a-time basis. An STM is not only an instrument that is used to ‘see’ individual atoms by means of imaging, but is also a tool that is used to ‘touch’ and ‘take’ the atoms, or to ‘hear’ their movements. Therefore, the STM can be considered as the ‘eyes’, ‘hands’ and ‘ears’ of the scientists, connecting our macroscopic world to the exciting atomic world. In this article, various STM atom manipulation schemes and their example applications are described. The future directions of atomic level assembly on surfaces using scanning probe tips are also discussed. (review article)

  20. Investigation of the nanoscale two-component ZnS-ZnO heterostructures by means of HR-TEM and X-ray based analysis

    Science.gov (United States)

    Pankin, I. A.; Polozhentsev, O. E.; Soldatov, M. A.; Bugaev, A. L.; Tsaturyan, A.; Lomachenko, K. A.; Guda, A. A.; Budnyk, A. P.; Lamberti, C.; Soldatov, A. V.

    2018-06-01

    This article is devoted to the spectroscopic characterization of ZnS-ZnO nanoscale heterostructures synthesized by the microwave-assisted solvothermal method. The synthesized samples were investigated by means of X-ray powder diffraction (XRPD), high energy resolution fluorescence detected X-ray absorption near-edge-structure (HERFD-XANES) spectroscopy, valence-to-core X-ray emission spectroscopy (VtC-XES) and high resolution transmission electron microscopy (HR-TEM) as well as energy dispersive X-ray spectroscopy (EDX). The average crystallite size estimated by the broadening of XRPD peaks increases from 2.7 nm to 3.7 nm in the temperature range from 100 °C to 150 °C. HR-TEM images show that nanoparticles are arranged in aggregates with the 60-200 nm size. Theoretical estimation shows that the systems synthesized at higher temperatures more prone to the agglomeration. The full profile Reitveld analysis of XRPD data reveals the formation of hexagonal zinc sulfide structure, whereas electron diffraction data reveal also the formation of cubic zinc sulfide and claim the polymorphous character of the system. High energy resolution Zn K-edge XANES data unambiguously demonstrate the presence of a certain amount of the zinc oxide which is likely to have an amorphous structure and could not be detected by XRPD. Qualitative analysis of XANES data allows deriving ZnS/ZnO ratio as a function of synthesis temperature. EDX analysis depicts homogeneous distribution of ZnS and amorphous ZnO phases across the conglomerates. A complementary element-selective valence to core X-ray emission spectroscopy evidences formation of two-component system and confirms estimations of ZnS/ZnO fractions obtained by linear combination fit of XANES data.

  1. Morphology and Chemical Composition of soot particles emitted by Wood-burning Cook-Stoves: a HRTEM, XPS and Elastic backscattering Studies.

    Science.gov (United States)

    Carabali-Sandoval, G. A., Sr.; Castro, T.; Peralta, O.; De la Cruz, W.; Días, J.; Amelines, O.; Rivera-Hernández, M.; Varela, A.; Muñoz-Muñoz, F.; Policroniades, R.; Murillo, G.; Moreno, E.

    2014-12-01

    The morphology, microstructure and the chemical composition on surface of soot particles were studied by using high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and elastic backscattering spectrometry. In order to obtain freshly soot particles emitted by home-made wood-burning cook stoves, copper grids for Transmission Electron Microscope (TEM) were placed on the last two of an 8-stages MOUDI cascade impactor. The analysis of HRTEM micrographs revealed the nanostructure and the particle size of soot particles. The XPS survey spectra show a large carbon peak around 285 eV and the oxygen signal at 533 eV. Some differences observed in the carbon/oxygen (C/O) ratio of the particles probably depend on the combustion process efficiency of each cook-stove analyzed. The C-1s XPS spectra show an asymmetric broad peak and other with low intensity that corresponds to sp2 and sp3hybridization, which were fitted with a convolution using Gaussian functions. Elastic backscattering technique allows a chemical elemental analysis of samples and confirms the presence of C, O and Si observed by XPS. Additionally, the morphological properties of soot aggregates were analyzed calculating the border-based fractal dimension (Df). Particles exhibit complex shapes with high values of Df. Also, real-time absorption (σabs) and scattering (σsct) coefficients of fine (with aerodynamic diameter < 2.5 µm) soot particles were measured. The trend in σabs and σsct indicate that the cooking process has two important combustion stages which varied in its flaming strength, being vigorous in the first stage and soft in the second one.

  2. Synchrotron radiation in atomic physics

    International Nuclear Information System (INIS)

    Crasemann, B.

    1998-01-01

    Much of present understanding of atomic and molecular structure and dynamics was gained through studies of photon-atom interactions. In particular, observations of the emission, absorption, and scattering of X rays have complemented particle-collision experiments in elucidating the physics of atomic inner shells. Grounded on Max von Laue's theoretical insight and the invention of the Bragg spectrometer, the field's potential underwent a step function with the development of synchrotron-radiation sources. Notably current third-generation sources have opened new horizons in atomic and molecular physics by producing radiation of wide tunability and exceedingly high intensity and polarization, narrow energy bandwidth, and sharp time structure. In this review, recent advances in synchrotron-radiation studies in atomic and molecular science are outlined. Some tempting opportunities are surveyed that arise for future studies of atomic processes, including many-body effects, aspects of fundamental photon-atom interactions, and relativistic and quantum-electrodynamic phenomena. (author)

  3. Atomic cluster collisions

    Science.gov (United States)

    Korol, Andrey V.; Solov'yov, Andrey

    2013-01-01

    Atomic cluster collisions are a field of rapidly emerging research interest by both experimentalists and theorists. The international symposium on atomic cluster collisions (ISSAC) is the premier forum to present cutting-edge research in this field. It was established in 2003 and the most recent conference was held in Berlin, Germany in July of 2011. This Topical Issue presents original research results from some of the participants, who attended this conference. This issues specifically focuses on two research areas, namely Clusters and Fullerenes in External Fields and Nanoscale Insights in Radiation Biodamage.

  4. Electron dose dependence of signal-to-noise ratio, atom contrast and resolution in transmission electron microscope images

    International Nuclear Information System (INIS)

    Lee, Z.; Rose, H.; Lehtinen, O.; Biskupek, J.; Kaiser, U.

    2014-01-01

    In order to achieve the highest resolution in aberration-corrected (AC) high-resolution transmission electron microscopy (HRTEM) images, high electron doses are required which only a few samples can withstand. In this paper we perform dose-dependent AC-HRTEM image calculations, and study the dependence of the signal-to-noise ratio, atom contrast and resolution on electron dose and sampling. We introduce dose-dependent contrast, which can be used to evaluate the visibility of objects under different dose conditions. Based on our calculations, we determine optimum samplings for high and low electron dose imaging conditions. - Highlights: • The definition of dose-dependent atom contrast is introduced. • The dependence of the signal-to-noise ratio, atom contrast and specimen resolution on electron dose and sampling is explored. • The optimum sampling can be determined according to different dose conditions

  5. Atomic polarizabilities

    International Nuclear Information System (INIS)

    Safronova, M. S.; Mitroy, J.; Clark, Charles W.; Kozlov, M. G.

    2015-01-01

    The atomic dipole polarizability governs the first-order response of an atom to an applied electric field. Atomic polarization phenomena impinge upon a number of areas and processes in physics and have been the subject of considerable interest and heightened importance in recent years. In this paper, we will summarize some of the recent applications of atomic polarizability studies. A summary of results for polarizabilities of noble gases, monovalent, and divalent atoms is given. The development of the CI+all-order method that combines configuration interaction and linearized coupled-cluster approaches is discussed

  6. Atomic polarizabilities

    Energy Technology Data Exchange (ETDEWEB)

    Safronova, M. S. [Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States); Mitroy, J. [School of Engineering, Charles Darwin University, Darwin NT 0909 (Australia); Clark, Charles W. [Joint Quantum Institute, National Institute of Standards and Technology and the University of Maryland, Gaithersburg, Maryland 20899-8410 (United States); Kozlov, M. G. [Petersburg Nuclear Physics Institute, Gatchina 188300 (Russian Federation)

    2015-01-22

    The atomic dipole polarizability governs the first-order response of an atom to an applied electric field. Atomic polarization phenomena impinge upon a number of areas and processes in physics and have been the subject of considerable interest and heightened importance in recent years. In this paper, we will summarize some of the recent applications of atomic polarizability studies. A summary of results for polarizabilities of noble gases, monovalent, and divalent atoms is given. The development of the CI+all-order method that combines configuration interaction and linearized coupled-cluster approaches is discussed.

  7. Atomic physics

    CERN Document Server

    Foot, Christopher J

    2007-01-01

    This text will thoroughly update the existing literature on atomic physics. Intended to accompany an advanced undergraduate course in atomic physics, the book will lead the students up to the latest advances and the applications to Bose-Einstein Condensation of atoms, matter-wave inter-ferometry and quantum computing with trapped ions. The elementary atomic physics covered in the early chapters should be accessible to undergraduates when they are first introduced to the subject. To complement. the usual quantum mechanical treatment of atomic structure the book strongly emphasizes the experimen

  8. Atomic physics

    International Nuclear Information System (INIS)

    Armbruster, P.; Beyer, H.; Bosch, F.; Dohmann, H.D.; Kozhuharov, C.; Liesen, D.; Mann, R.; Mokler, P.H.

    1984-01-01

    The heavy ion accelerator UNILAC is well suited to experiments in the field of atomic physics because, with the aid of high-energy heavy ions atoms can be produced in exotic states - that is, heavy atoms with only a few electrons. Also, in close collisions of heavy ions (atomic number Z 1 ) and heavy target atoms (Z 2 ) short-lived quasi-atomic 'superheavy' systems will be formed - huge 'atoms', where the inner electrons are bound in the field of the combined charge Z 1 + Z 2 , which exceeds by far the charge of the known elements (Z <= 109). Those exotic or transient superheavy atoms delivered from the heavy ion accelerator make it possible to study for the first time in a terrestrial laboratory exotic, but fundamental, processes, which occur only inside stars. Some of the basic research carried out with the UNILAC is discussed. This includes investigation of highly charged heavy atoms with the beam-foil method, the spectroscopy of highly charged slow-recoil ions, atomic collision studies with highly ionised, decelerated ions and investigations of super-heavy quasi-atoms. (U.K.)

  9. Ultracold atoms on atom chips

    DEFF Research Database (Denmark)

    Krüger, Peter; Hofferberth, S.; Haller, E.

    2005-01-01

    Miniaturized potentials near the surface of atom chips can be used as flexible and versatile tools for the manipulation of ultracold atoms on a microscale. The full scope of possibilities is only accessible if atom-surface distances can be reduced to microns. We discuss experiments in this regime...

  10. Ubiquitous atom

    International Nuclear Information System (INIS)

    Spruch, G.M.; Spruch, L.

    1974-01-01

    The fundamentals of modern physics, including the basic physics and chemistry of the atom, elementary particles, cosmology, periodicity, and recent advances, are surveyed. The biology and chemistry of the life process is discussed to provide a background for considering the effects of atomic particles on living things. The uses of atomic power in space travel, merchant shipping, food preservation, desalination, and nuclear clocks are explored. (Pollut. Abstr.)

  11. Atomic physics

    International Nuclear Information System (INIS)

    Anon.

    1976-01-01

    Research activities in atomic physics at Lawrence Berkeley Laboratory during 1976 are described. Topics covered include: experiments on stored ions; test for parity violation in neutral weak currents; energy conservation and astrophysics; atomic absorption spectroscopy, atomic and molecular detectors; theoretical studies of quantum electrodynamics and high-z ions; atomic beam magnetic resonance; radiative decay from the 2 3 Po, 2 levels of helium-like argon; quenching of the metastable 2S/sub 1/2/ state of hydrogen-like argon in an external electric field; and lifetime of the 2 3 Po level of helium-like krypton

  12. TEM and HRTEM study of oxide particles in an Al-alloyed high-Cr oxide dispersion strengthened ferritic steel with Hf addition

    Energy Technology Data Exchange (ETDEWEB)

    Dou, Peng, E-mail: doup@tsinghua.edu.cn [School of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Kimura, Akihiko, E-mail: kimura@iae.kyoto-u.ac.jp [Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Kasada, Ryuta, E-mail: r-kasada@iae.kyoto-u.ac.jp [Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Okuda, Takanari, E-mail: okuda.takanari@kki.kobelco.com [Kobelco Research Institute, 1-5-5 Takatsukadai, Nishi-ku, Kobe, Hyogo 651-2271 (Japan); Inoue, Masaki, E-mail: inoue.masaki@jaea.go.jp [Advanced Nuclear System R& D Directorate, Japan Atomic Energy Agency, 4002 Narita, O-arai, Ibaraki 311-1393 (Japan); Ukai, Shigeharu, E-mail: s-ukai@eng.hokudai.ac.jp [Graduate School of Engineering, Hokkaido University, N13, W8, Kita-ku, Sapporo 060-8628 (Japan); Ohnuki, Somei, E-mail: ohnuki@eng.hokudai.ac.jp [Graduate School of Engineering, Hokkaido University, N13, W8, Kita-ku, Sapporo 060-8628 (Japan); Fujisawa, Toshiharu, E-mail: fujisawa@esi.nagoya-u.ac.jp [EcoTopia Science Institute, Nagoya University, Furo, Chikusa-ku, Nagoya 464-8603 (Japan); Abe, Fujio, E-mail: ABE.Fujio@nims.go.jp [Structural Metals Center, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Jiang, Shan, E-mail: js93518@gmail.com [School of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); Yang, Zhigang, E-mail: zgyang@tsinghua.edu.cn [Key Laboratory of Advanced Materials (MOE), School of Materials Sciences and Engineering, Tsinghua University, Beijing 100084 (China)

    2017-03-15

    The nanoparticles in an Al-alloyed high-Cr oxide dispersion strengthened (ODS) ferritic steel with Hf addition, i.e., SOC-16 (Fe-15Cr-2W-0.1Ti-4Al-0.62Hf-0.35Y{sub 2}O{sub 3}), have been examined by transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). Relative to an Al-alloyed high-Cr ODS ferritic steel without Hf addition, i.e., SOC-9 (Fe-15.5Cr-2W-0.1Ti-4Al-0.35Y{sub 2}O{sub 3}), the dispersion morphology and coherency of the oxide nanoparticles in SOC-16 were significantly improved. Almost all the small nanoparticles (diameter <10 nm) in SOC-16 were found to be consistent with cubic Y{sub 2}Hf{sub 2}O{sub 7} oxides with the anion-deficient fluorite structure and coherent with the bcc steel matrix. The larger particles (diameter >10 nm) were also mainly identified as cubic Y{sub 2}Hf{sub 2}O{sub 7} oxides with the anion-deficient fluorite structure. The results presented here are compared with those of SOC-9 with a brief discussion of the underlying mechanisms of the unusual thermal and irradiation stabilities of the oxides as well as the superior strength, excellent irradiation tolerance and extraordinary corrosion resistance of SOC-16.

  13. TEM and HRTEM study of oxide particles in an Al-alloyed high-Cr oxide dispersion strengthened ferritic steel with Hf addition

    International Nuclear Information System (INIS)

    Dou, Peng; Kimura, Akihiko; Kasada, Ryuta; Okuda, Takanari; Inoue, Masaki; Ukai, Shigeharu; Ohnuki, Somei; Fujisawa, Toshiharu; Abe, Fujio; Jiang, Shan; Yang, Zhigang

    2017-01-01

    The nanoparticles in an Al-alloyed high-Cr oxide dispersion strengthened (ODS) ferritic steel with Hf addition, i.e., SOC-16 (Fe-15Cr-2W-0.1Ti-4Al-0.62Hf-0.35Y 2 O 3 ), have been examined by transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). Relative to an Al-alloyed high-Cr ODS ferritic steel without Hf addition, i.e., SOC-9 (Fe-15.5Cr-2W-0.1Ti-4Al-0.35Y 2 O 3 ), the dispersion morphology and coherency of the oxide nanoparticles in SOC-16 were significantly improved. Almost all the small nanoparticles (diameter <10 nm) in SOC-16 were found to be consistent with cubic Y 2 Hf 2 O 7 oxides with the anion-deficient fluorite structure and coherent with the bcc steel matrix. The larger particles (diameter >10 nm) were also mainly identified as cubic Y 2 Hf 2 O 7 oxides with the anion-deficient fluorite structure. The results presented here are compared with those of SOC-9 with a brief discussion of the underlying mechanisms of the unusual thermal and irradiation stabilities of the oxides as well as the superior strength, excellent irradiation tolerance and extraordinary corrosion resistance of SOC-16.

  14. HRTEM Study of Oxide Nanoparticles in 16Cr-4Al-2W-0.3Ti-0.3Y2O3 ODS Steel

    Energy Technology Data Exchange (ETDEWEB)

    Hsiung, L; Fluss, M; Wall, M; Kimura, A

    2009-11-18

    Crystal and interfacial structures of oxide nanoparticles in 16Cr-4Al-2W-0.3Ti-0.3Y{sub 2}O{sub 3} ODS ferritic steel have been examined using high-resolution transmission electron microscopy (HRTEM) techniques. Oxide nanoparticles with a complex-oxide core and an amorphous shell were frequently observed. The crystal structure of complex-oxide core is identified to be mainly monoclinic Y{sub 4}Al{sub 2}O{sub 9} (YAM) oxide compound. Orientation relationships between the oxide and matrix are found to be dependent on the particle size. Large particles (> 20 nm) tend to be incoherent and have a spherical shape, whereas small particles (< 10 nm) tend to be coherent or semi-coherent and have a faceted interface. The observations of partially amorphous nanoparticles lead us to propose three-stage mechanisms to rationalize the formation of oxide nanoparticles containing core/shell structures in as-fabricated ODS steels.

  15. Crystal potential retrieval in HRTEM

    International Nuclear Information System (INIS)

    Beeching, M.J.; Spargo, A.E.C.

    1993-01-01

    A possible method for obtaining the crystal potential by inversion of the complex wavefield at the exit surface of the specimen, based on reversal of the multi-slice algorithm, is outlined. Results from preliminary testing of the method using computer simulated data are presented and appear promising, although the limits of applicability of the method are yet to be defined. 13 refs., 5 figs

  16. Atomic physics

    CERN Document Server

    Born, Max

    1969-01-01

    The Nobel Laureate's brilliant exposition of the kinetic theory of gases, elementary particles, the nuclear atom, wave-corpuscles, atomic structure and spectral lines, electron spin and Pauli's principle, quantum statistics, molecular structure and nuclear physics. Over 40 appendices, a bibliography, numerous figures and graphs.

  17. Early Atomism

    Indian Academy of Sciences (India)

    https://www.ias.ac.in/article/fulltext/reso/015/10/0905-0925. Keywords. Atomic theory; Avogadro's hypothesis; atomic weights; periodic table; valence; molecular weights; molecular formula; isomerism. Author Affiliations. S Ramasesha1. Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560 012, ...

  18. Atom spectroscopy

    International Nuclear Information System (INIS)

    Kodling, K.

    1981-01-01

    Experiments on atom photoabsorption spectroscopy using synchrotron radiation in the 10-1000 eV range are reviewed. Properties of the necessary synchrotron radiation and the experiment on absorption spectroscopy are briefly described. Comparison with other spectroscopy methods is conducted. Some data on measuring photoabsorption, photoelectron emission and atom mass spectra are presented [ru

  19. Exotic atoms

    International Nuclear Information System (INIS)

    Horvath, D.; Lambrecht, R.M.

    1984-01-01

    This bibliography on exotic atoms covers the years 1939 till 1982. The annual entries are headed by an introduction describing the state of affairs of the branch of science and listing the main applications in quantum electrodynamics, particle physics, nuclear physics, atomic physics, chemical physics and biological sciences. The bibliography includes an author index and a subject index. (Auth.)

  20. Atomic fusion, Gerrard atomic fusion

    International Nuclear Information System (INIS)

    Gerrard, T.H.

    1980-01-01

    In the approach to atomic fusion described here the heat produced in a fusion reaction, which is induced in a chamber by the interaction of laser beams and U.H.F. electromagnetic beams with atom streams, is transferred to a heat exchanger for electricity generation by a coolant flowing through a jacket surrounding the chamber. (U.K.)

  1. Superradiators created atom by atom

    Science.gov (United States)

    Meschede, Dieter

    2018-02-01

    High radiation rates are usually associated with macroscopic lasers. Laser radiation is “coherent”—its amplitude and phase are well-defined—but its generation requires energy inputs to overcome loss. Excited atoms spontaneously emit in a random and incoherent fashion, and for N such atoms, the emission rate simply increases as N. However, if these atoms are in close proximity and coherently coupled by a radiation field, this microscopic ensemble acts as a single emitter whose emission rate increases as N2 and becomes “superradiant,” to use Dicke's terminology (1). On page 662 of this issue, Kim et al. (2) show the buildup of coherent light fields through collective emission from atomic radiators injected one by one into a resonator field. There is only one atom ever in the cavity, but the emission is still collective and superradiant. These results suggest another route toward thresholdless lasing.

  2. Atomic structure of Mg-based metallic glass investigated with neutron diffraction, reverse Monte Carlo modeling and electron microscopy

    Directory of Open Access Journals (Sweden)

    Rafał Babilas

    2017-05-01

    Full Text Available The structure of a multicomponent metallic glass, Mg65Cu20Y10Ni5, was investigated by the combined methods of neutron diffraction (ND, reverse Monte Carlo modeling (RMC and high-resolution transmission electron microscopy (HRTEM. The RMC method, based on the results of ND measurements, was used to develop a realistic structure model of a quaternary alloy in a glassy state. The calculated model consists of a random packing structure of atoms in which some ordered regions can be indicated. The amorphous structure was also described by peak values of partial pair correlation functions and coordination numbers, which illustrated some types of cluster packing. The N = 9 clusters correspond to the tri-capped trigonal prisms, which are one of Bernal’s canonical clusters, and atomic clusters with N = 6 and N = 12 are suitable for octahedral and icosahedral atomic configurations. The nanocrystalline character of the alloy after annealing was also studied by HRTEM. The selected HRTEM images of the nanocrystalline regions were also processed by inverse Fourier transform analysis. The high-angle annular dark-field (HAADF technique was used to determine phase separation in the studied glass after heat treatment. The HAADF mode allows for the observation of randomly distributed, dark contrast regions of about 4–6 nm. The interplanar spacing identified for the orthorhombic Mg2Cu crystalline phase is similar to the value of the first coordination shell radius from the short-range order.

  3. Atomic interferometry

    International Nuclear Information System (INIS)

    Baudon, J.; Robert, J.

    2004-01-01

    Since the theoretical works of L. De Broglie (1924) and the famous experiment of Davisson and Germer (1927), we know that a wave is linked with any particle of mass m by the relation λ = h/(mv), where λ is the wavelength, v the particle velocity and h is the Planck constant. The basic principle of the interferometry of any material particle, atom, molecule or aggregate is simple: using a simple incident wave, several mutually consistent waves (with well-defined relative phases) are generated and controllable phase-shifts are introduced between them in order to generate a wave which is the sum of the previous waves. An interference figure is obtained which consists in a succession of dark and bright fringes. The atomic interferometry is based on the same principle but involves different techniques, different wave equations, but also different beams, sources and correlations which are described in this book. Because of the small possible wavelengths and the wide range of possible atomic interactions, atomic interferometers can be used in many domains from the sub-micron lithography to the construction of sensors like: inertial sensors, gravity-meters, accelerometers, gyro-meters etc. The first chapter is a preliminary study of the space and time diffraction of atoms. The next chapters is devoted to the description of slit, light separation and polarization interferometers, and the last chapter treats of the properties of Bose-Einstein condensates which are interesting in atomic interferometry. (J.S.)

  4. Atomic insight into tribochemical wear mechanism of silicon at the Si/SiO{sub 2} interface in aqueous environment: Molecular dynamics simulations using ReaxFF reactive force field

    Energy Technology Data Exchange (ETDEWEB)

    Wen, Jialin; Ma, Tianbao [State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China); Zhang, Weiwei; Psofogiannakis, George; Duin, Adri C.T. van [Department of Mechanical and Nuclear Engineering, Pennsylvania State University, University Park, PA 16802 (United States); Chen, Lei; Qian, Linmao [Tribology Research Institute, Key Laboratory of Advanced Technologies of Materials (Ministry of Education), Southwest Jiaotong University, Chengdu 610031 (China); Hu, Yuanzhong [State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China); Lu, Xinchun, E-mail: xclu@tsinghua.edu.cn [State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China)

    2016-12-30

    Highlights: • New ReaxFF reactive force field was applied to simulate the tribochemical wear process at Si/SiO{sub 2} interface. • Wear of silicon atoms is due to the breaking of Si–O–Si bonds and Si–Si–O–Si bond chains on the Si substrate. • Interfacial bridge bonds play an important role during the tribochemical wear process. • Higher pressures applied to the silica phase can cause more Si atoms to be removed by forming more interfacial bridge bonds. • Water plays an opposing role in the wear process because of its both chemical and mechanical effects. - Abstract: In this work, the atomic mechanism of tribochemical wear of silicon at the Si/SiO{sub 2} interface in aqueous environment was investigated using ReaxFF molecular dynamics (MD) simulations. Two types of Si atom removal pathways were detected in the wear process. The first is caused by the destruction of stretched Si–O–Si bonds on the Si substrate surface and is assisted by the attachment of H atoms on the bridging oxygen atoms of the bonds. The other is caused by the rupture of Si–Si bonds in the stretched Si–Si–O–Si bond chains at the interface. Both pathways effectively remove Si atoms from the silicon surface via interfacial Si–O–Si bridge bonds. Our simulations also demonstrate that higher pressures applied to the silica phase can cause more Si atoms to be removed due to the formation of increased numbers of interfacial Si–O–Si bridge bonds. Besides, water plays a dual role in the wear mechanism, by oxidizing the Si substrate surface as well as by preventing the close contact of the surfaces. This work shows that the removal of Si atoms from the substrate is a result of both chemical reaction and mechanical effects and contributes to the understanding of tribochemical wear behavior in the microelectromechanical systems (MEMS) and Si chemical mechanical polishing (CMP) process.

  5. Atomic politics

    International Nuclear Information System (INIS)

    Skogmar, G.

    1979-01-01

    The authors basic point is that the military and civil sides of atomic energy cannot be separated. The general aim of the book is to analyze both the military and civil branches, and the interdependence between them, of American foreign policy in the atomic field. Atomic policy is seen as one of the most important imstruments of foreign policy which, in turn, is seen against the background of American imperialism in general. Firstly, the book investigates the most important means by which the United States has controlled the development in the nuclear field in other countries. These means include influencing the conditions of access to nuclear resources of various kinds, influencing the flow of technical-economic information and influencing international organizations and treaties bearing on atomic energy. The time period treated is 1945-1973. 1973 is chosen as the end-year of the study mainly because of the new conditions in the whole energy field initiated by the oil crisis in that year. The sources of the empirical work are mainly hearings before the Joint Committee on Atomic Energy of the U.S. Congress and legal material of various kinds. Secondly, the goals of the American policy are analyzed. The goals identified are armament effect, non-proliferation (horizontal), sales, and energy dependence. The relation between the main goals is discussed.The discussion is centered on the interdependence between the military and the civil aspects, conflict and coincidence of various goals, the relation between short-term and long-term goals, and the possibilities of using one goal as pretext for another. Thirdly, some causes of the changes in the atomic policy around 1953 and 1963 are identified. These are the strategic balance, the competitive situation, the capacity (of the American atomic productive apparatus), and the nuclear technological stage. The specific composition of these four factors at the two time-points can explain the changes of policy. (author)

  6. Atomic secrecy

    International Nuclear Information System (INIS)

    Sweet, W.

    1979-01-01

    An article, The H-Bomb Secret: How We Got It, Why We're Telling It, by Howard Morland was to be published in The Progressive magazine in February, 1979. The government, after learning of the author's and the editors' intention to publish the article and failing to persuade them to voluntarily delete about 20% of the text and all of the diagrams showing how an H-bomb works, requested a court injunction against publication. Acting under the Atomic Energy Act of 1954, US District Court Judge Robert W. Warren granted the government's request on March 26. Events dealing with the case are discussed in this publication. Section 1, Progressive Hydrogen Bomb Case, is discussed under the following: Court Order Blocking Magazine Report; Origins of the Howard Morland Article; Author's Motives, Defense of Publication; and Government Arguments Against Disclosure. Section 2, Access to Atomic Data Since 1939, contains information on need for secrecy during World War II; 1946 Atomic Energy Act and its effects; Soviet A-Bomb and the US H-Bomb; and consequences of 1954 Atomic Energy Act. Section 3, Disputed Need for Atomic Secrecy, contains papers entitled: Lack of Studies on H-Bomb Proliferation; Administration's Position on H-Bombs; and National Security Needs vs Free Press

  7. Africa Insight

    African Journals Online (AJOL)

    Africa Insight is a quarterly, peer-reviewed journal of the Africa Institute of South Africa. It is accredited by the South African National Department of Higher Education and Training (DHET) and is indexed in the International Bibliography of Social Science (IBSS). It is a multi-disciplinary journal primarily focusing on African ...

  8. Collision-produced atomic states

    International Nuclear Information System (INIS)

    Andersen, N.; Copenhagen Univ.

    1988-01-01

    The last 10-15 years have witnessed the development of a new, powerful class of experimental techniques for atomic collision studies, allowing partial or complete determination of the state of the atoms after a collision event, i.e. the full set of quantum-mechanical scattering amplitudes or - more generally - the density matrix describing the system. Evidently, such studies, involving determination of alignment and orientation parameters, provide much more severe tests of state-of-the-art scattering theories than do total or differential cross section measurements which depend on diagonal elements of the density matrix. The off-diagonal elements give us detailed information about the shape and dynamics of the atomic states. Therefore, close studies of collision-produced atomic states are currently leading to deeper insights into the fundamental physical mechanisms governing the dynamics of atomic collision events. The first part of the lectures deals with the language used to describe atomic states, while the second part presents a selection of recent results for model systems which display fundamental aspects of the collision physics in particularly instructive ways. I shall here restrict myself to atom-atom collisions. The discussion will be focused on states decaying by photon emission though most of the ideas can be easily modified to include electron emission as well. (orig./AH)

  9. Antimatter atoms

    International Nuclear Information System (INIS)

    Anon.

    1996-01-01

    In january 1996, CERN broadcasted the information of the creation of nine anti-hydrogen atoms, observed through disintegration products. The experimental facility was CERN LEAR ring. An antiproton beam scattered a xenon jet, and the resulting antimatter was first selected by its insensitivity to beam bending magnets. Their disintegration was detected in thin NaI detectors, in which the anti-atoms are at once deprived from their positron. Then, magnetic and time-of-flight spectrometers are used. (D.L.)

  10. Atomic theories

    CERN Document Server

    Loring, FH

    2014-01-01

    Summarising the most novel facts and theories which were coming into prominence at the time, particularly those which had not yet been incorporated into standard textbooks, this important work was first published in 1921. The subjects treated cover a wide range of research that was being conducted into the atom, and include Quantum Theory, the Bohr Theory, the Sommerfield extension of Bohr's work, the Octet Theory and Isotopes, as well as Ionisation Potentials and Solar Phenomena. Because much of the material of Atomic Theories lies on the boundary between experimentally verified fact and spec

  11. High-energy atomic physics

    CERN Document Server

    Drukarev, Evgeny G

    2016-01-01

    This self-contained text introduces readers to the field of high-energy atomic physics - a new regime of photon-atom interactions in which the photon energies significantly exceed the atomic or molecular binding energies, and which opened up with the recent advent of new synchrotron sources. From a theoretical point of view, a small-parameter characteristic of the bound system emerged, making it possible to perform analytic perturbative calculations that can in turn serve as benchmarks for more powerful numerical computations. The first part of the book introduces readers to the foundations of this new regime and its theoretical treatment. In particular, the validity of the small-parameter perturbation expansion and of the lowest-order approximation is critically reviewed. The following chapters then apply these insights to various atomic processes, such as photoionization as a many-body problem, dominant mechanisms for the production of ions at higher energies, Compton scattering and ionization accompanied b...

  12. Coherent Radiation in Atomic Systems

    Science.gov (United States)

    Sutherland, Robert Tyler

    Over the last century, quantum mechanics has dramatically altered our understanding of light and matter. Impressively, exploring the relationship between the two continues to provide important insights into the physics of many-body systems. In this thesis, we add to this still growing field of study. Specifically, we discuss superradiant line-broadening and cooperative dipole-dipole interactions for cold atom clouds in the linear-optics regime. We then discuss how coherent radiation changes both the photon scattering properties and the excitation distribution of atomic arrays. After that, we explore the nature of superradiance in initially inverted clouds of multi-level atoms. Finally, we explore the physics of clouds with degenerate Zeeman ground states, and show that this creates quantum effects that fundamentally change the photon scattering of atomic ensembles.

  13. Atoms stories

    International Nuclear Information System (INIS)

    Radvanyi, P.; Bordry, M.

    1988-01-01

    Physicists from different countries told each evening during one learning week, to an audience of young people, some great discoveries in evoking the difficulties and problems to which the researchers were confronted. From Antiquity to a more recent history, it is a succession of atoms stories. (N.C.)

  14. Atomic physics

    International Nuclear Information System (INIS)

    Held, B.

    1991-01-01

    This general book describes the change from classical physics to quantum physics. The first part presents atom evolution since antiquity and introduces fundamental quantities and elements of relativity. Experiments which have contributed to the evolution of knowledge on matter are analyzed in the second part. Applications of wave mechanics to the study of matter properties are presented in the third part [fr

  15. Imaging Lithium Atoms at Sub-Angstrom Resolution

    Energy Technology Data Exchange (ETDEWEB)

    O' Keefe, Michael A.; Shao-Horn, Yang

    2005-01-03

    John Cowley and his group at ASU were pioneers in the use of transmission electron microscopy (TEM) for high-resolution imaging. Three decades ago they achieved images showing the crystal unit cell content at better than 4A resolution. Over the years, this achievement has inspired improvements in resolution that have enabled researchers to pinpoint the positions of heavy atom columns within the cell. More recently, this ability has been extended to light atoms as resolution has improved. Sub-Angstrom resolution has enabled researchers to image the columns of light atoms (carbon, oxygen and nitrogen) that are present in many complex structures. By using sub-Angstrom focal-series reconstruction of the specimen exit surface wave to image columns of cobalt, oxygen, and lithium atoms in a transition metal oxide structure commonly used as positive electrodes in lithium rechargeable batteries, we show that the range of detectable light atoms extends to lithium. HRTEM at sub-Angstrom resolution will provide the essential role of experimental verification for the emergent nanotech revolution. Our results foreshadow those to be expected from next-generation TEMs with CS-corrected lenses and monochromated electron beams.

  16. Atom-surface potentials and atom interferometry

    International Nuclear Information System (INIS)

    Babb, J.F.

    1998-01-01

    Long-range atom-surface potentials characterize the physics of many actual systems and are now measurable spectroscopically in deflection of atomic beams in cavities or in reflection of atoms in atomic fountains. For a ground state, spherically symmetric atom the potential varies as -1/R 3 near the wall, where R is the atom-surface distance. For asymptotically large distances the potential is weaker and goes as -1/R 4 due to retardation arising from the finite speed of light. This diminished interaction can also be interpreted as a Casimir effect. The possibility of measuring atom-surface potentials using atomic interferometry is explored. The particular cases studied are the interactions of a ground-state alkali-metal atom and a dielectric or a conducting wall. Accurate descriptions of atom-surface potentials in theories of evanescent-wave atomic mirrors and evanescent wave-guided atoms are also discussed. (author)

  17. Exotic atoms

    International Nuclear Information System (INIS)

    Kunselman, R.

    1993-01-01

    The experiments use a solid hydrogen layer to form muonic hydrogen isotopes that escape into vacuum. The method relies on transfer of the muon from protium to either a deuteron or a triton. The resulting muonic deuterium or muonic tritium will not immediately thermalize because of the very low elastic cross sections, and may be emitted from the surface of the layer. Measurements which detect decay electrons, muonic x-rays, and fusion products have been used to study the processes. A target has been constructed which exploits muonic atom emission in order to learn more about the energy dependence of transfer and muon molecular formation

  18. New insights into the toxicity of mineral fibres: A combined in situ synchrotron μ-XRD and HR-TEM study of chrysotile, crocidolite, and erionite fibres found in the tissues of Sprague-Dawley rats.

    Science.gov (United States)

    Gualtieri, Alessandro F; Bursi Gandolfi, Nicola; Pollastri, Simone; Burghammer, Manfred; Tibaldi, Eva; Belpoggi, Fiorella; Pollok, Kilian; Langenhorst, Falko; Vigliaturo, Ruggero; Dražić, Goran

    2017-05-15

    Along the line of the recent research topic aimed at understanding the in vivo activity of mineral fibres and their mechanisms of toxicity, this work describes the morpho-chemical characteristics of the mineral fibres found in the tissues of Sprague-Dawley rats subjected to intraperitoneal/intrapleural injection of UICC chrysotile, UICC crocidolite and erionite-Na from Nevada (USA). The fibres are studied with in situ synchrotron powder diffraction and high resolution transmission electron microscopy to improve our understanding of the mechanisms of toxicity of these mineral fibres. In contact with the tissues of the rats, chrysotile fibres are prone to dissolve, with leaching of Mg and production of a silica rich relict. On the other hand, crocidolite and erionite-Na fibres are stable even for very long contact times within the tissues of the rats, showing just a thin dissolution amorphous halo. These findings support the model of a lower biopersistence of chrysotile with respect to crocidolite and erionite-Na but the formation of a silica-rich fibrous residue after the pseudo-amorphization of chrysotile may justify a higher cytotoxic potential and intense inflammatory activity of chrysotile in the short term in contact with the lung tissues. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Atom Skimmers and Atom Lasers Utilizing Them

    Science.gov (United States)

    Hulet, Randall; Tollett, Jeff; Franke, Kurt; Moss, Steve; Sackett, Charles; Gerton, Jordan; Ghaffari, Bita; McAlexander, W.; Strecker, K.; Homan, D.

    2005-01-01

    Atom skimmers are devices that act as low-pass velocity filters for atoms in thermal atomic beams. An atom skimmer operating in conjunction with a suitable thermal atomic-beam source (e.g., an oven in which cesium is heated) can serve as a source of slow atoms for a magneto-optical trap or other apparatus in an atomic-physics experiment. Phenomena that are studied in such apparatuses include Bose-Einstein condensation of atomic gases, spectra of trapped atoms, and collisions of slowly moving atoms. An atom skimmer includes a curved, low-thermal-conduction tube that leads from the outlet of a thermal atomic-beam source to the inlet of a magneto-optical trap or other device in which the selected low-velocity atoms are to be used. Permanent rare-earth magnets are placed around the tube in a yoke of high-magnetic-permeability material to establish a quadrupole or octupole magnetic field leading from the source to the trap. The atoms are attracted to the locus of minimum magnetic-field intensity in the middle of the tube, and the gradient of the magnetic field provides centripetal force that guides the atoms around the curve along the axis of the tube. The threshold velocity for guiding is dictated by the gradient of the magnetic field and the radius of curvature of the tube. Atoms moving at lesser velocities are successfully guided; faster atoms strike the tube wall and are lost from the beam.

  20. Atomic bonding between metal and graphene

    KAUST Repository

    Wang, Hongtao

    2013-03-07

    To understand structural and chemical properties of metal-graphene composites, it is crucial to unveil the chemical bonding along the interface. We provide direct experimental evidence of atomic bonding between typical metal nano structures and graphene, agreeing well with density functional theory studies. Single Cr atoms are located in the valleys of a zigzag edge, and few-atom ensembles preferentially form atomic chains by self-assembly. Low migration barriers lead to rich dynamics of metal atoms and clusters under electron irradiation. We demonstrate no electron-instigated interaction between Cr clusters and pristine graphene, though Cr has been reported to be highly reactive to graphene. The metal-mediated etching is a dynamic effect between metal clusters and pre-existing defects. The resolved atomic configurations of typical nano metal structures on graphene offer insight into modeling and simulations on properties of metal-decorated graphene for both catalysis and future carbon-based electronics. © 2013 American Chemical Society.

  1. Gold volatile species atomization and preconcentration in quartz devices for atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Arslan, Yasin [Institute of Analytical Chemistry of the ASCR, v. v. i., Veveří 97, 602 00 Brno (Czech Republic); Mehmet Akif Ersoy University, Faculty of Arts & Sciences, Chemistry Department, 15030 Burdur (Turkey); Musil, Stanislav; Matoušek, Tomáš; Kratzer, Jan [Institute of Analytical Chemistry of the ASCR, v. v. i., Veveří 97, 602 00 Brno (Czech Republic); Dědina, Jiří, E-mail: dedina@biomed.cas.cz [Institute of Analytical Chemistry of the ASCR, v. v. i., Veveří 97, 602 00 Brno (Czech Republic)

    2015-01-01

    The on-line atomization of gold volatile species was studied and the results were compared with thermodynamic calculations in several quartz atomizers, namely: diffusion flame, flame-in-gas-shield, flame-in-plain-tube, externally heated T-tube and externally heated flame-in-T-tube. Atomization mechanism in the explored devices is proposed, where volatile species are converted to thermodynamically stable AuH at elevated temperature over 500 °C and then atomized by an interaction with a cloud of hydrogen radicals. Because of its inherent simplicity and robustness, diffusion flame was employed as a reference atomizer. It yielded atomization efficiency of 70 to 100% and a very good long time reproducibility of peak area sensitivity: 1.6 to 1.8 s μg{sup −1}. Six and eleven times higher sensitivity, respectively, was provided by atomizers with longer light paths in the observation volume, i.e. externally heated T-tube and externally heated flame-in-T-tube. The latter one, offering limit of detection below 0.01 μg ml{sup −1}, appeared as the most prospective for on-line atomization. Insight into the mechanism of atomization of gold volatile species, into the fate of free atoms and into subsequent analyte transfer allowed to assess possibilities of in-atomizer preconcentration of gold volatile species: it is unfeasible with quartz atomizers but a sapphire tube atomizer could be useful in this respect. - Highlights: • On-line atomization of gold volatile species for AAS in quartz devices was studied. • Atomization mechanism was proposed and atomization efficiency was estimated. • Possibilities of in-atomizer preconcentration of gold volatile species were assessed.

  2. Cold experiment of slag centrifugal granulation by rotary atomizer: Effect of atomizer configuration

    International Nuclear Information System (INIS)

    Wu, Jun-Jun; Wang, Hong; Zhu, Xun; Liao, Qiang; Li, Kai

    2017-01-01

    Centrifugal granulation has recently been employed to produce small blast furnace slag particles, so as to recover the waste heat from the high-temperature molten blast furnace slag. An appropriate atomizer enables centrifugal granulation to become a better cost-effective process for particle production. Thus, increasing emphasis has been placed on influence of atomizer configuration on granulation. In present study, three groups of atomizers were specially designed and the granulation performance of each atomizer was experimentally tested during cold experiments. The influences of atomizer configuration on granulation modes and droplet characteristics were investigated visually. Two modified correlations were proposed to predict the granulating droplet size by means of data fitting. The results indicated that the rotary cup atomizers can inhibit the film formation in contrast to rotary disc atomizer. Moreover, atomizers with outer angle of 90° was capable of producing smaller droplets. The revised correlation as well as the newly-developed correlation including the influence of atomizer configurations, presented in good agreement with the experiment data. In addition, an analysis on atomizer design was conducted to provide a good insight for industrialization. It was recommended to adopt cup-like atomizer in granulation for its ability to produce fine particles with smaller atomizer size.

  3. Characterization of microstructural evolution in Fe-C(-Mn) alloys during early stages of ageing using atom probe

    International Nuclear Information System (INIS)

    Xiong, X.Y.; Tran, P.; Pereloma, E.; Ringer, S.P.

    2004-01-01

    Full text: Extensive studies on the effect of ageing treatment on the micro structure and mechanical properties of most commercial ferritic (a) Fe-C(-X) alloys reveal age-hardening characteristics that involve a monotonic increase towards a peak hardness after several hours of ageing. Peak hardness is always associated with the formation of precipitate particles (e.g: MnC 3 ). However, there is relatively little systematic work on the very early stages of ageing using direct nanostructural analysis and many questions remain on the potential for clustering of interstitial C atoms prior to the precipitation reaction. In this experimental work, we report a small but significant hardness peak within 300 sec during ageing at 550 deg C. High resolution transmission electron microscopy (HRTEM) observations did not show any microstructural change during this early stage of ageing. In order to understand the microstructural evolution in ultra-low carbon a-Fe-C(-Mn) alloys during these early stages of ageing, 3-dimensional atom probe (3DAP) has been used to examine the C atom distribution and possible segregation of C and Mn atoms in these alloys. In this report, the 3DAP analyses and HRTEM observations of Fe-C and Fe-C-Mn alloys are correlated with age hardening measurements and possible mechanisms of the initial hardening phenomenon will be discussed

  4. Atomic reactor thermal engineering

    International Nuclear Information System (INIS)

    Kim, Gwang Ryong

    1983-02-01

    This book starts the introduction of atomic reactor thermal engineering including atomic reaction, chemical reaction, nuclear reaction neutron energy and soon. It explains heat transfer, heat production in the atomic reactor, heat transfer of fuel element in atomic reactor, heat transfer and flow of cooler, thermal design of atomic reactor, design of thermodynamics of atomic reactor and various. This deals with the basic knowledge of thermal engineering for atomic reactor.

  5. Atomic energy

    International Nuclear Information System (INIS)

    Ramanna, R.

    1978-01-01

    Development of nuclear science in India, particularly the research and development work at the Bhabha Atomic Research Centre (BARC), Bombay, is described. Among the wide range of materials developed for specific functions under rigorous conditions are nuclear pure grade uranium, zirconium and beryllium, and conventional materials like aluminium, carbon steel and stainless steels. Radioisotopes are produced and used for tracer studies in various fields. Various types of nuclear gauges and nuclear instruments are produced. Radiations have been used to develop new high yielding groundnut mutants with large kernals. The sterile male technique for pest control and radiosterilization technique to process potatoes, onions and marine foods for storage are ready for exploitation. Processes and equipment have been developed for production of electrolytic hydrogen, electrothermal phosphorus and desalinated water. Indigenously manufactured components and materials are now being used for the nuclear energy programme. Indian nuclear power programme strategy is to build heavy water reactors and to utilise their byproduct plutonium and depleted uranium to feed fast breeder reactors which will produce more fissile material than burnt. Finally a special mention has been made of the manpower development programme of the BARC. BARC has established a training school in 1957 giving advanced training in physics, chemistry and various branches of engineering and metallurgy

  6. Bremsstrahlung in atom-atom collisions

    International Nuclear Information System (INIS)

    Amus'ya, M.Y.; Kuchiev, M.Y.; Solov'ev, A.V.

    1985-01-01

    It is shown that in the collision of a fast atom with a target atom when the frequencies are on the order of the potentials or higher, there arises bremsstrahlung comparable in intensity with the bremsstrahlung emitted by an electron with the same velocity in the field of the target atom. The mechanism by which bremsstrahlung is produced in atom-atom collisions is elucidated. Results of specific calculations of the bremsstrahlung spectra are given for α particles and helium atoms colliding with xenon

  7. Atomic weight versus atomic mass controversy

    International Nuclear Information System (INIS)

    Holden, N.E.

    1985-01-01

    A problem for the Atomic Weights Commission for the past decade has been the controversial battle over the names ''atomic weight'' and ''atomic mass''. The Commission has considered the arguments on both sides over the years and it appears that this meeting will see more of the same discussion taking place. In this paper, I review the situation and offer some alternatives

  8. Highly excited atoms

    International Nuclear Information System (INIS)

    Kleppner, D.; Littman, M.G.; Zimmerman, M.L.

    1981-01-01

    Highly excited atoms are often called Rydberg atoms. These atoms have a wealth of exotic properties which are discussed. Of special interest, are the effects of electric and magnetic fields on Rydberg atoms. Ordinary atoms are scarcely affected by an applied electric or magnetic field; Rydberg atoms can be strongly distorted and even pulled apart by a relatively weak electric field, and they can be squeezed into unexpected shapes by a magnetic field. Studies of the structure of Rydberg atoms in electric and magnetic fields have revealed dramatic atomic phenomena that had not been observed before

  9. Laser-assisted atom-atom collisions

    International Nuclear Information System (INIS)

    Roussel, F.

    1984-01-01

    The basic layer-assisted atom-atom collision processes are reviewed in order to get a simpler picture of the main physical facts. The processes can be separated into two groups: optical collisions where only one atom is changing state during the collision, the other acting as a spectator atom, and radiative collisions where the states of the two atoms are changing during the collision. All the processes can be interpreted in terms of photoexcitation of the quasimolecule formed during the collisional process. (author)

  10. Transformation mechanism of n-butyl terminated Si nanoparticles embedded into Si1-xCx nanocomposites mixed with Si nanoparticles and C atoms

    International Nuclear Information System (INIS)

    Shin, J.W.; Oh, D.H.; Kim, T.W.; Cho, W.J.

    2009-01-01

    Bright-field transmission electron microscopy (TEM) images, high-resolution TEM (HRTEM) images, and fast-Fourier transformed electron-diffraction patterns showed that n-butyl terminated Si nanoparticles were aggregated. The formation of Si 1-x C x nanocomposites was mixed with Si nanoparticles and C atoms embedded in a SiO 2 layer due to the diffusion of C atoms from n-butyl termination shells into aggregated Si nanoparticles. Atomic force microscopy (AFM) images showed that the Si 1-x C x nanocomposites mixed with Si nanoparticles and C atoms existed in almost all regions of the SiO 2 layer. The formation mechanism of Si nanoparticles and the transformation mechanism of n-butyl terminated Si nanoparticles embedded into Si 1-x C x nanocomposites mixed with Si nanoparticles and C atoms are described on the basis of the TEM, HRTEM, and AFM results. These results can help to improve the understanding of the formation mechanism of Si nanoparticles.

  11. Code ATOM for calculation of atomic characteristics

    International Nuclear Information System (INIS)

    Vainshtein, L.A.

    1990-01-01

    In applying atomic physics to problems of plasma diagnostics, it is necessary to determine some atomic characteristics, including energies and transition probabilities, for very many atoms and ions. Development of general codes for calculation of many types of atomic characteristics has been based on general but comparatively simple approximate methods. The program ATOM represents an attempt at effective use of such a general code. This report gives a brief description of the methods used, and the possibilities of and limitations to the code are discussed. Characteristics of the following processes can be calculated by ATOM: radiative transitions between discrete levels, radiative ionization and recombination, collisional excitation and ionization by electron impact, collisional excitation and ionization by point heavy particle (Born approximation only), dielectronic recombination, and autoionization. ATOM explores Born (for z=1) or Coulomb-Born (for z>1) approximations. In both cases exchange and normalization can be included. (N.K.)

  12. Atomic fountain and applications

    International Nuclear Information System (INIS)

    Rawat, H.S.

    2000-01-01

    An overview of the development of working of MOT along with the basic principle of laser atom cooling and trapping is given. A technique to separate the cooled and trapped atoms from the MOT using atomic fountain technique will also be covered. The widely used technique for atomic fountain is, first to cool and trap the neutral atoms in MOT and then launch them in the vertical direction, using moving molasses technique. Using 133 Cs atomic fountain clock, time improvement of 2 to 3 order of magnitude over a conventional 133 Cs atomic clock has been observed

  13. Interferometry with atoms

    International Nuclear Information System (INIS)

    Helmcke, J.; Riehle, F.; Witte, A.; Kisters, T.

    1992-01-01

    Physics and experimental results of atom interferometry are reviewed and several realizations of atom interferometers are summarized. As a typical example of an atom interferometer utilizing the internal degrees of freedom of the atom, we discuss the separated field excitation of a calcium atomic beam using four traveling laser fields and demonstrate the Sagnac effect in a rotating interferometer. The sensitivity of this interferometer can be largely increased by use of slow atoms with narrow velocity distribution. We therefore furthermore report on the preparation of a laser cooled and deflected calcium atomic beam. (orig.)

  14. Three-atom clusters

    International Nuclear Information System (INIS)

    Pen'kov, F.M.

    1998-01-01

    The Born-Oppenheimer approximation is used to obtain an equation for the effective interaction in three atoms bound by a single electron. For low binding energies in an 'electron + atom' pair, long-range forces arise between the atoms, leading to bound states when the size of the three-atom cluster is a few tens of angstrom. A system made of alkali-metal atoms is considered as an example

  15. Stable atomic hydrogen: Polarized atomic beam source

    International Nuclear Information System (INIS)

    Niinikoski, T.O.; Penttilae, S.; Rieubland, J.M.; Rijllart, A.

    1984-01-01

    We have carried out experiments with stable atomic hydrogen with a view to possible applications in polarized targets or polarized atomic beam sources. Recent results from the stabilization apparatus are described. The first stable atomic hydrogen beam source based on the microwave extraction method (which is being tested ) is presented. The effect of the stabilized hydrogen gas density on the properties of the source is discussed. (orig.)

  16. Advances in atomic spectroscopy

    CERN Document Server

    Sneddon, J

    2000-01-01

    This fifth volume of the successful series Advances in Atomic Spectroscopy continues to discuss and investigate the area of atomic spectroscopy.It begins with a description of the use of various atomic spectroscopic methods and applications of speciation studies in atomic spectroscopy. The emphasis is on combining atomic spectroscopy with gas and liquid chromatography. In chapter two the authors describe new developments in tunable lasers and the impact they will have on atomic spectroscopy. The traditional methods of detection, such as photography and the photomultiplier, and how they are being replaced by new detectors is discussed in chapter three. The very active area of glow discharge atomic spectrometry is presented in chapter four where, after a brief introduction and historical review, the use of glow discharge lamps for atomic spectroscopy and mass spectrometry are discussed. Included in this discussion is geometry and radiofrequency power. The future of this source in atomic spectroscopy is also dis...

  17. Atomic and molecular manipulation

    CERN Document Server

    Mayne, Andrew J

    2011-01-01

    Work with individual atoms and molecules aims to demonstrate that miniaturized electronic, optical, magnetic, and mechanical devices can operate ultimately even at the level of a single atom or molecule. As such, atomic and molecular manipulation has played an emblematic role in the development of the field of nanoscience. New methods based on the use of the scanning tunnelling microscope (STM) have been developed to characterize and manipulate all the degrees of freedom of individual atoms and molecules with an unprecedented precision. In the meantime, new concepts have emerged to design molecules and substrates having specific optical, mechanical and electronic functions, thus opening the way to the fabrication of real nano-machines. Manipulation of individual atoms and molecules has also opened up completely new areas of research and knowledge, raising fundamental questions of "Optics at the atomic scale", "Mechanics at the atomic scale", Electronics at the atomic scale", "Quantum physics at the atomic sca...

  18. Microfabricated Waveguide Atom Traps.

    Energy Technology Data Exchange (ETDEWEB)

    Jau, Yuan-Yu [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-09-01

    A nanoscale , microfabricated waveguide structure can in - principle be used to trap atoms in well - defined locations and enable strong photon-atom interactions . A neutral - atom platform based on this microfabrication technology will be prealigned , which is especially important for quantum - control applications. At present, there is still no reported demonstration of evanescent - field atom trapping using a microfabricated waveguide structure. We described the capabilities established by our team for future development of the waveguide atom - trapping technology at SNL and report our studies to overcome the technical challenges of loading cold atoms into the waveguide atom traps, efficient and broadband optical coupling to a waveguide, and the waveguide material for high - power optical transmission. From the atomic - physics and the waveguide modeling, w e have shown that a square nano-waveguide can be utilized t o achieve better atomic spin squeezing than using a nanofiber for first time.

  19. Progress in atomic spectroscopy

    International Nuclear Information System (INIS)

    Beyer, H.J.; Kleinpoppen, H.

    1984-01-01

    This book presents reviews by leading experts in the field covering areas of research at the forefront of atomic spectroscopy. Topics considered include the k ordering of atomic structure, multiconfiguration Hartree-Fock calculations for complex atoms, new methods in high-resolution laser spectroscopy, resonance ionization spectroscopy (inert atom detection), trapped ion spectroscopy, high-magnetic-field atomic physics, the effects of magnetic and electric fields on highly excited atoms, x rays from superheavy collision systems, recoil ion spectroscopy with heavy ions, investigations of superheavy quasi-atoms via spectroscopy of electron rays and positrons, impact ionization by fast projectiles, and amplitudes and state parameters from ion- and atom-atom excitation processes

  20. Atomic Fisher information versus atomic number

    International Nuclear Information System (INIS)

    Nagy, A.; Sen, K.D.

    2006-01-01

    It is shown that the Thomas-Fermi Fisher information is negative. A slightly more sophisticated model proposed by Gaspar provides a qualitatively correct expression for the Fisher information: Gaspar's Fisher information is proportional to the two-third power of the atomic number. Accurate numerical calculations show an almost linear dependence on the atomic number

  1. Atomic-fluorescence spectrophotometry

    International Nuclear Information System (INIS)

    Bakhturova, N.F.; Yudelevich, I.G.

    1975-01-01

    Atomic-fluorescence spectrophotometry, a comparatively new method for the analysis of trace quantities, has developed rapidly in the past ten years. Theoretical and experimental studies by many workers have shown that atomic-fluorescence spectrophotometry (AFS) is capable of achieving a better limit than atomic absorption for a large number of elements. The present review examines briefly the principles of atomic-fluorescence spectrophotometry and the types of fluorescent transition. The excitation sources, flame and nonflame atomizers, used in AFS are described. The limits of detection achieved up to the present, using flame and nonflame methods of atomization are given

  2. Atomic scale chemical tomography of human bone

    Science.gov (United States)

    Langelier, Brian; Wang, Xiaoyue; Grandfield, Kathryn

    2017-01-01

    Human bone is a complex hierarchical material. Understanding bone structure and its corresponding composition at the nanometer scale is critical for elucidating mechanisms of biomineralization under healthy and pathological states. However, the three-dimensional structure and chemical nature of bone remains largely unexplored at the nanometer scale due to the challenges associated with characterizing both the structural and chemical integrity of bone simultaneously. Here, we use correlative transmission electron microscopy and atom probe tomography for the first time, to our knowledge, to reveal structures in human bone at the atomic level. This approach provides an overlaying chemical map of the organic and inorganic constituents of bone on its structure. This first use of atom probe tomography on human bone reveals local gradients, trace element detection of Mg, and the co-localization of Na with the inorganic-organic interface of bone mineral and collagen fibrils, suggesting the important role of Na-rich organics in the structural connection between mineral and collagen. Our findings provide the first insights into the hierarchical organization and chemical heterogeneity in human bone in three-dimensions at its smallest length scale - the atomic level. We demonstrate that atom probe tomography shows potential for new insights in biomineralization research on bone.

  3. Proofs that Develop Insight

    Science.gov (United States)

    Weber, Keith

    2010-01-01

    Many mathematics educators have noted that mathematicians do not only read proofs to gain conviction but also to obtain insight. The goal of this article is to discuss what this insight is from mathematicians' perspective. Based on interviews with nine research-active mathematicians, two sources of insight are discussed. The first is reading a…

  4. A Single Atom Antenna

    International Nuclear Information System (INIS)

    Trinter, Florian; Williams, Joshua B; Weller, Miriam; Waitz, Markus; Pitzer, Martin; Voigtsberger, Jörg; Schober, Carl; Kastirke, Gregor; Müller, Christian; Goihl, Christoph; Burzynski, Phillip; Wiegandt, Florian; Wallauer, Robert; Kalinin, Anton; Schmidt, Lothar Ph H; Schöffler, Markus S; Jahnke, Till; Dörner, Reinhard; Chiang, Ying-Chih; Gokhberg, Kirill

    2015-01-01

    Here we demonstrate the smallest possible implementation of an antenna-receiver complex which consists of a single (helium) atom acting as the antenna and a second (neon) atom acting as a receiver. (paper)

  5. The infancy of atomic physics Hercules in his cradle

    CERN Document Server

    Keller, Alex

    1983-01-01

    Atomic physics is a mighty Hercules that dominates modern civilization, promising immense reserves of power but threatening catastrophic war and radioactive pollution. The story of the atom's discovery and the development of techniques to harness its energy offers fascinating insights into the forces behind twenty-first-century technology. This compelling history portrays the human faces and lives behind the beginnings of atomic science.The Infancy of Atomic Physics ranges from experiments in the 1880s by William Crookes and others to the era just after the First World War, when Rutherford's f

  6. Atom chips: mesoscopic physics with cold atoms

    International Nuclear Information System (INIS)

    Krueger, P.; Wildermuth, S.; Hofferberth, S.; Haller, E.; GAllego Garcia, D.; Schmiedmayer, J.

    2005-01-01

    Full text: Cold neutral atoms can be controlled and manipulated in microscopic potentials near surfaces of atom chips. These integrated micro-devices combine the known techniques of atom optics with the capabilities of well established micro- and nanofabrication technology. In analogy to electronic microchips and integrated fiber optics, the concept of atom chips is suitable to explore the domain of mesoscopic physics with matter waves. We use current and charge carrying structures to form complex potentials with high spatial resolution only microns from the surface. In particular, atoms can be confined to an essentially one-dimensional motion. In this talk, we will give an overview of our experiments studying the manipulation of both thermal atoms and BECs on atom chips. First experiments in the quasi one-dimensional regime will be presented. These experiments profit from strongly reduced residual disorder potentials caused by imperfections of the chip fabrication with respect to previously published experiments. This is due to our purely lithographic fabrication technique that proves to be advantageous over electroplating. We have used one dimensionally confined BECs as an ultra-sensitive probe to characterize these potentials. These smooth potentials allow us to explore various aspects of the physics of degenerate quantum gases in low dimensions. (author)

  7. Atomic Energy Control Act

    International Nuclear Information System (INIS)

    1970-01-01

    This act provides for the establishment of the Atomic Energy Control Board. The board is responsible for the control and supervision of the development, application and use of atomic energy. The board is also considered necessary to enable Canada to participate effectively in measures of international control of atomic energy

  8. Atomic Spectra Database (ASD)

    Science.gov (United States)

    SRD 78 NIST Atomic Spectra Database (ASD) (Web, free access)   This database provides access and search capability for NIST critically evaluated data on atomic energy levels, wavelengths, and transition probabilities that are reasonably up-to-date. The NIST Atomic Spectroscopy Data Center has carried out these critical compilations.

  9. Measurement of the indium segregation in InGaN based LEDs with single atom sensitivity

    International Nuclear Information System (INIS)

    Jinschek, Joerg; Kisielowski, Christian; Van Dyck, Dirk; Geuens, Philippe

    2003-01-01

    In light emitting diodes (LED) consisting of GaN/InGaN/GaN quantum wells (QWs), the exact indium distribution inside the wells of the active region affects the performance of devices. Indium segregation can take place forming small InGaN clusters of locally varying composition. In the past, we used a local strain analysis from single HRTEM lattice images to determine the In composition inside the InGaN QWs with a resolution of 0.5 nm x 0.3 nm. Truly atomic resolution can be pursued by exploitation of intensity dependencies on the atomic number (Z) of the electron exit-wave (EW). In microscopes with sufficient sensitivity, local variations of amplitude and phase are found to be discrete with sample thickness, which allows for counting the number of atoms in each individual column of ∼0.08 nm diameter. In QW s of ∼17 percent of average indium concentration it is possible to discriminate between pure Ga columns and columns containing 1, 2, 3, or more In atoms because phase changes are discrete and element specific. The preparation of samples with atomically flat surfaces is a limiting factor for the application of the procedure

  10. Atom-atom collision cascades localization

    International Nuclear Information System (INIS)

    Kirsanov, V.V.

    1980-01-01

    The presence of an impurity and thermal vibration influence on the atom-atom collision cascade development is analysed by the computer simulation method (the modificated dynamic model). It is discovered that the relatively low energetic cascades are localized with the temperature increase of an irradiated crystal. On the basis of the given effect the mechanism of splitting of the high energetic cascades into subcascades is proposed. It accounts for two factors: the primary knocked atom energy and the irradiated crystal temperature. Introduction of an impurity also localizes the cascades independently from the impurity atom mass. The cascades localization leads to intensification of the process of annealing in the cascades and reduction of the post-cascade vacancy cluster sizes. (author)

  11. Atomic-resolution studies of In2O3-ZnO compounds on aberration-corrected electron microscopes

    International Nuclear Information System (INIS)

    Yu, Wentao

    2009-01-01

    In this work, the characteristic inversion domain microstructures of In 2 O 3 (ZnO) m (m=30) compounds were investigated by TEM methods. At bright-atom contrast condition, atomically resolved HR-TEM images of In 2 O 3 (ZnO) 30 were successfully acquired in [1 anti 100] zone axis of ZnO, with projected metal columns of ∝1.6 A well resolved. From contrast maxima in the TEM images, local lattice distortions at the pyramidal inversion domain boundaries were observed for the first time. Lattice displacements and the strain field in two-dimensions were visualized and measured using the 'DALI' algorithm. Atomically resolved single shot and focal series images of In 2 O 3 (ZnO) 30 were achieved in both zone axes of ZnO, [1 anti 100] and [2 anti 1 anti 10], respectively. The electron waves at the exit-plane were successfully reconstructed using the software package 'TrueImage'. Finally, a three dimensional atomic structure model for the pyramidal IDB was proposed, with an In distribution of 10%, 20%, 40%, 20% and 10% of In contents over 5 atom columns along basal planes, respectively. Through a detailed structural study of In 2 O 3 (ZnO) m compounds by using phase-contrast and Z-contrast imaging at atomic resolution, In 3+ atoms are determined with trigonal bi-pyramidal co-ordination and are distributed at the pyramidal IDBs. (orig.)

  12. X-ray spectroscopy from exotic atoms

    International Nuclear Information System (INIS)

    Hartmann, F.J.

    1994-01-01

    Why do experimentalists study exotic atoms, in particular antiprotonic atoms? The answer is simple: the information about electromagnetic, weak, and strong interactions that can be obtained by doing X-ray spectroscopy from exotic atoms is really worth the effort. It is possible to (1) enlarge the knowledge about the properties of exotic particles (such as mass and magnetic moment); (2) open a possibility to test quantum electrodynamics; (3) get detailed insight into the shape of nuclei (characterized by the nuclear radium and higher momenta) and even into the neutron distribution in the nucleus (neutron halo); and (4) use it as a powerful tool to learn about the strong interaction at very low relative hadron-nucleon velocities

  13. Schroedinger cat states and multilevel atoms

    International Nuclear Information System (INIS)

    Shore, B.W.; Knight, P.L.

    1993-01-01

    We demonstrate that the generalization of the two-level Jaynes-Cummings model (JCM) to an N-level atom leads to the creation of up to N macroscopically distinct field states. These field states are Schmidt-orthogonalized superpositions of Fock states. They correspond to macroscopic states of the field, attainable with large mean photon numbers. Unlike the situation with a two-level atom and a coherent-state field, which evolves into a macroscopic coherent superposition state (a Schrodinger cat), we find that when the additional levels participate strongly in the excitation (e.g all transitions are resonant with equal dipole moments) then the system does not evolve into a pure state. We will present some examples of special cases, giving insight into the behavior of three-level atoms and the two-level two-photon JCM

  14. Handbook of hot atom chemistry

    International Nuclear Information System (INIS)

    Adloff, J.P.; Matsuura, Tatsuo; Yoshihara, Kenji

    1992-01-01

    Hot atom chemistry is an increasingly important field, which has contributed significantly to our understanding of many fundamental processes and reactions. Its techniques have become firmly entrenched in numerous disciplines, such as applied physics, biomedical research, and all fields of chemistry. Written by leading experts, this comprehensive handbook encompasses a broad range of topics. Each chapter comprises a collection of stimulating essays, given an in-depth account of the state-of-the-art of the field, and stressing opportunities for future work. An extensive introduction to the whole area, this book provides unique insight into a vast subject, and a clear delineation of its goals, techniques, and recent findings. It also contains detailed discussions of applications in fields as diverse as nuclear medicine, geochemistry, reactor technology, and the chemistry of comets and interstellar grains. (orig.)

  15. Atomic collisions research with excited atomic species

    International Nuclear Information System (INIS)

    Hoogerland, M.D.; Gulley, R.J.; Colla, M.; Lu, W.; Milic, D.; Baldwin, K.G.H.; Buckman, S.J.

    1999-01-01

    Measurements and calculations of fundamental atomic collision and spectroscopic properties such as collision cross sections, reaction rates, transition probabilities etc. underpin the understanding and operation of many plasma and gas-discharge-based devices and phenomena, for example plasma processing and deposition. In almost all cases the complex series of reactions which sustains the discharge or plasma, or produces the reactive species of interest, has a precursor electron impact excitation, attachment, dissociation or ionisation event. These processes have been extensively studied in a wide range of atomic and molecular species and an impressive data base of collision cross sections and reaction rates now exists. However, most of these measurements are for collisions with stable atomic or molecular species which are initially in their ground electronic state. Relatively little information is available for scattering from excited states or for scattering from unstable molecular radicals. Examples of such species would be metastable excited rare gases, which are often used as buffer gases, or CF 2 radicals formed by electron impact dissociation in a CF 4 plasma processing discharge. We are interested in developing experimental techniques which will enable the quantitative study of such exotic atomic and molecular species. In this talk I would like to outline one such facility which is being used for studies of collisions with metastable He(2 3 S) atoms

  16. Atoms - molecules - nuclei. Vol. 1

    International Nuclear Information System (INIS)

    Otter, G.; Honecker, R.

    1993-01-01

    This first volume covers the following topics: Wave-particle dualism, classical atomic physics; the Schroedinger equation, angular momentum in quantum physics, one-electron atoms and many-electron atoms with atomic structure, atomic spectra, exotic atoms, influence of electric and magnetic fields

  17. Atomic and molecular sciences

    International Nuclear Information System (INIS)

    Lane, N.F.

    1989-01-01

    The theoretical atomic and molecular physics program at Rice University addresses basic questions about the collision dynamics of electrons, atoms, ions and molecules, emphasizing processes related to possible new energy technologies and other applications. The program focuses on inelastic collision processes that are important in understanding energy and ionization balance in disturbed gases and plasmas. Emphasis is placed on systems and processes where some experimental information is available or where theoretical results may be expected to stimulate new measurements. Examples of current projects include: excitation and charge-transfer processes; orientation and alignment of excited states following collisions; Rydberg atom collisions with atoms and molecules; Penning ionization and ion-pair formation in atom-atom collisions; electron-impact ionization in dense, high-temperature plasmas; electron-molecule collisions; and related topics

  18. Modern atomic physics

    CERN Document Server

    Natarajan, Vasant

    2015-01-01

    Much of our understanding of physics in the last 30-plus years has come from research on atoms, photons, and their interactions. Collecting information previously scattered throughout the literature, Modern Atomic Physics provides students with one unified guide to contemporary developments in the field. After reviewing metrology and preliminary material, the text explains core areas of atomic physics. Important topics discussed include the spontaneous emission of radiation, stimulated transitions and the properties of gas, the physics and applications of resonance fluorescence, coherence, cooling and trapping of charged and neutral particles, and atomic beam magnetic resonance experiments. Covering standards, a different way of looking at a photon, stimulated radiation, and frequency combs, the appendices avoid jargon and use historical notes and personal anecdotes to make the topics accessible to non-atomic physics students. Written by a leader in atomic and optical physics, this text gives a state-of-the...

  19. Atomic Scale Chemical and Structural Characterization of Ceramic Oxide Heterostructure Interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Singh, R. K.

    2003-04-16

    The research plan was divided into three tasks: (a) growth of oxide heterostructures for interface engineering using standard thin film deposition techniques, (b) atomic level characterization of oxide heterostructure using such techniques as STEM-2 combined with AFM/STM and conventional high-resolution microscopy (HRTEM), and (c) property measurements of aspects important to oxide heterostructures using standard characterization methods, including dielectric properties and dynamic cathodoluminescence measurements. Each of these topics were further classified on the basis of type of oxide heterostructure. Type I oxide heterostructures consisted of active dielectric layers, including the materials Ba{sub x}Sr{sub 1-x}TiO{sub 3} (BST), Y{sub 2}O{sub 3} and ZrO{sub 2}. Type II heterostructures consisted of ferroelectric active layers such as lanthanum manganate and Type III heterostructures consist of phosphor oxide active layers such as Eu-doped Y{sub 2}O{sub 3}.

  20. Metal atom oxidation laser

    International Nuclear Information System (INIS)

    Jensen, R.J.; Rice, W.W.; Beattie, W.H.

    1975-01-01

    A chemical laser which operates by formation of metal or carbon atoms and reaction of such atoms with a gaseous oxidizer in an optical resonant cavity is described. The lasing species are diatomic or polyatomic in nature and are readily produced by exchange or other abstraction reactions between the metal or carbon atoms and the oxidizer. The lasing molecules may be metal or carbon monohalides or monoxides

  1. Advances in atomic spectroscopy

    CERN Document Server

    Sneddon, J

    1997-01-01

    This series describes selected advances in the area of atomic spectroscopy. It is primarily intended for the reader who has a background in atmoic spectroscopy; suitable to the novice and expert. Although a widely used and accepted method for metal and non-metal analysis in a variety of complex samples, Advances in Atomic Spectroscopy covers a wide range of materials. Each Chapter will completely cover an area of atomic spectroscopy where rapid development has occurred.

  2. Economical Atomic Layer Deposition

    Science.gov (United States)

    Wyman, Richard; Davis, Robert; Linford, Matthew

    2010-10-01

    Atomic Layer Deposition is a self limiting deposition process that can produce films at a user specified height. At BYU we have designed a low cost and automated atomic layer deposition system. We have used the system to deposit silicon dioxide at room temperature using silicon tetrachloride and tetramethyl orthosilicate. Basics of atomic layer deposition, the system set up, automation techniques and our system's characterization are discussed.

  3. Atomic physics made clear

    International Nuclear Information System (INIS)

    Meinhold, H.

    1980-01-01

    This book is a popular introduction into the foundations of atomic physics und quantum mechanics. Starting from some phenomenological concepts Bohr's model and the construction of the periodic system regarding the shell structure of atoms are introduced. In this framework the selection rules and magnetic moments of atomic electrons are considered. Finally the wave-particle dualism is considered. In the appendix some mathematical methods are described which are useful for a deeper penetration into the considered ideas. (HSI)

  4. In Search of Insight.

    Science.gov (United States)

    Kaplan, Craig A.; Simon, Herbert A.

    1990-01-01

    Attaining the insight needed to solve the Mutilated Checkerboard problem, which requires discovery of an effective problem representation (EPR), is described. Performance on insight problems can be predicted from the availability of generators and constraints in the search for an EPR. Data for 23 undergraduates were analyzed. (TJH)

  5. Deeply bound pionic atom

    International Nuclear Information System (INIS)

    Toki, Hiroshi; Yamazaki, Toshimitsu

    1989-01-01

    The standard method of pionic atom formation does not produce deeply bound pionic atoms. A study is made on the properties of deeply bound pionic atom states by using the standard pion-nucleus optical potential. Another study is made to estimate the cross sections of the formation of ls pionic atom states by various methods. The pion-nucleus optical potential is determined by weakly bound pionic atom states and pion nucleus scattering. Although this potential may not be valid for deeply bound pionic atoms, it should provide some hint on binding energies and level widths of deeply bound states. The width of the ls state comes out to be 0.3 MeV and is well separated from the rest. The charge dependence of the ls state is investigated. The binding energies and the widths increase linearly with Z azbove a Z of 30. The report then discusses various methods to populate deeply bound pionic atoms. In particular, 'pion exchange' reactions are proposed. (n, pπ) reaction is discussed first. The cross section is calculated by assuming the in- and out-going nucleons on-shell and the produced pion in (n1) pionic atom states. Then, (n, dπ - ) cross sections are estimated. (p, 2 Heπ - ) reaction would have cross sections similar to the cross section of (n, dπ - ) reaction. In conclusion, it seems best to do (n, p) experiment on heavy nuclei for deeply bound pionic atom. (Nogami, K.)

  6. Single atom oscillations

    International Nuclear Information System (INIS)

    Wiorkowski, P.; Walther, H.

    1990-01-01

    Modern methods of laser spectroscopy allow the study of single atoms or ions in an unperturbed environment. This has opened up interesting new experiments, among them the detailed study of radiation-atom coupling. In this paper, the following two experiments dealing with this problem are reviewed: the single-atom maser and the study of the resonance fluorescence of a single stored ion. The simplest and most fundamental system for studying radiation-matter coupling is a single two-level atom interacting with a single mode of an electromagnetic field in a cavity. This problem received a great deal of attention shortly after the maser was invented

  7. Atomic hydrogen reactor

    International Nuclear Information System (INIS)

    Massip de Turville, C.M.D.

    1982-01-01

    Methods are discussed of generating heat in an atomic hydrogen reactor which involve; the production of atomic hydrogen by an electrical discharge, the capture of nascent neutrons from atomic hydrogen in a number of surrounding steel alloy tubes having a high manganese content to produce 56 Mn, the irradiation of atomic hydrogen by the high energy antineutrinos from the beta decay of 56 Mn to yield nascent neutrons, and the removal of the heat generated by the capture of nascent neutrons by 55 Mn and the beta decay of 56 Mn. (U.K.)

  8. Response to the comment by C. Kisielowski, H.A. Calderon, F.R. Chen, S. Helveg, J.R. Jinschek, P. Specht, D. Van Dyck on the article "On the influence of the electron dose-rate on the HRTEM image contrast" by J. Barthel, M. Lentzen, A. Thust, Ultramicroscopy 176 (2017) 37-45.

    Science.gov (United States)

    Barthel, Juri; Lentzen, Markus; Thust, Andreas

    2017-08-01

    In a recent article [1] we examined the influence of the applied electron dose rate on the magnitude of the image contrast in high-resolution transmission electron microscopy (HRTEM). We concluded that the magnitude of the image contrast is not substantially affected by the applied electron dose rate. This result is in obvious contradiction to numerous earlier publications by Kisielowski and coworkers [2-7], who commented our recent article due to this contradiction. The present short communication is a response to the comment of Kisielowski and coworkers on our recent article, where we provide additional arguments supporting our initial findings and conclusions on the magnitude of the image contrast in HRTEM. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Atomic Step Formation on Sapphire Surface in Ultra-precision Manufacturing

    Science.gov (United States)

    Wang, Rongrong; Guo, Dan; Xie, Guoxin; Pan, Guoshun

    2016-01-01

    Surfaces with controlled atomic step structures as substrates are highly relevant to desirable performances of materials grown on them, such as light emitting diode (LED) epitaxial layers, nanotubes and nanoribbons. However, very limited attention has been paid to the step formation in manufacturing process. In the present work, investigations have been conducted into this step formation mechanism on the sapphire c (0001) surface by using both experiments and simulations. The step evolutions at different stages in the polishing process were investigated with atomic force microscopy (AFM) and high resolution transmission electron microscopy (HRTEM). The simulation of idealized steps was constructed theoretically on the basis of experimental results. It was found that (1) the subtle atomic structures (e.g., steps with different sawteeth, as well as steps with straight and zigzag edges), (2) the periodicity and (3) the degree of order of the steps were all dependent on surface composition and miscut direction (step edge direction). A comparison between experimental results and idealized step models of different surface compositions has been made. It has been found that the structure on the polished surface was in accordance with some surface compositions (the model of single-atom steps: Al steps or O steps). PMID:27444267

  10. Atom dynamics in laser fields

    International Nuclear Information System (INIS)

    Jang, Su; Mi, No Gin

    2004-12-01

    This book introduces coherent dynamics of internal state, spread of atoms wave speed, semiclassical atoms density matrix such as dynamics equation in both still and moving atoms, excitation of atoms in movement by light, dipole radiating power, quantum statistical mechanics by atoms in movement, semiclassical atoms in movement, atoms in movement in the uniform magnetic field including effects of uniform magnetic field, atom cooling using laser such as Doppler cooling, atom traps using laser and mirrors, radiant heat which particles receive, and near field interactions among atoms in laser light.

  11. Atoms stories; Histoire d`atomes

    Energy Technology Data Exchange (ETDEWEB)

    Radvanyi, P; Bordry, M [Centre National de la Recherche Scientifique (CNRS), 75 - Paris (France)

    1988-12-31

    Physicists from different countries told each evening during one learning week, to an audience of young people, some great discoveries in evoking the difficulties and problems to which the researchers were confronted. From Antiquity to a more recent history, it is a succession of atoms stories. (N.C.)

  12. Low energy atom-atom collisions

    International Nuclear Information System (INIS)

    Child, M.S.

    1980-01-01

    The semiclassical theory of atom-atom potential scattering and of low energy inelastic atom-atom scattering is reviewed. Particular attention is given to the origin and interpretation of rainbow structure, diffraction oscillations and exchange oscillations in the potential scattering differential cross-section, and to the glory structure and symmetry oscillations in the integral cross-section. Available methods for direct inversion of the cross-section data to recover the potential are reviewed in some detail. The theory of non-adiabatic transitions is introduced by a short discussion of interaction mechanisms and of diabetic and adiabatic representations. Analytical S matrix elements are presented for two state curve-crossing (Landau-Zener-Stuckelberg), Demkov and Nikitin models. The relation between Stuckelberg oscillations in the S matrix and in the differential cross-section is discussed in terms of interference between trajectories belonging to two different classical deflection functions. The energy dependences of the inelastic integral cross-section for curve-crossing and Demkov type transitions are also discussed. Finally the theory is reviewed in relation to a recent close-coupled study of fine structure transitions in F( 2 P) + Xe( 2 S) scattering

  13. Atoms, Molecules, and Compounds

    CERN Document Server

    Manning, Phillip

    2007-01-01

    Explores the atoms that govern chemical processes. This book shows how the interactions between simple substances such as salt and water are crucial to life on Earth and how those interactions are predestined by the atoms that make up the molecules.

  14. Atomic Energy Control Board

    International Nuclear Information System (INIS)

    Blackman, N.S.; Gummer, W.K.

    1982-02-01

    This paper has been prepared to provide an overview of the responsibilities and activities of the Atomic Energy Control Board. It is designed to address questions that are often asked concerning the establishment of the Atomic Energy Control Board, its enabling legislation, licensing and compliance activities, federal-provincial relationships, international obligations, and communications with the public

  15. mu. -nucleon atoms

    Energy Technology Data Exchange (ETDEWEB)

    Dobretsov, Yu; Dolgoshein, B; Kirillov-Ugryumov, V

    1980-12-01

    The properties and formation are described of ..mu..-nucleon atoms, the Larmor method of muon spin precession is discussed and the experimental confirmation of the existence of ..mu..-nucleon atoms is shown. The prospects of their use are indicated.

  16. μ-nucleon atoms

    International Nuclear Information System (INIS)

    Dobretsov, Yu.; Dolgoshejn, B.; Kirillov-Ugryumov, V.

    1980-01-01

    The properties and formation are described of μ-nucleon atoms, the Larmor method of muon spin precession is discussed and the experimental confirmation of the existence of μ-nucleon atoms is shown. The prospects of their use are indicated. (J.P.)

  17. Atomic Ferris wheel beams

    Science.gov (United States)

    Lembessis, Vasileios E.

    2017-07-01

    We study the generation of atom vortex beams in the case where a Bose-Einstein condensate, released from a trap and moving in free space, is diffracted from a properly tailored light mask with a spiral transverse profile. We show how such a diffraction scheme could lead to the production of an atomic Ferris wheel beam.

  18. Atom lithography of Fe

    NARCIS (Netherlands)

    Sligte, te E.; Smeets, B.; van der Stam, K.M.R.; Herfst, R.W.; Straten, van der P.; Beijerinck, H.C.W.; Leeuwen, van K.A.H.

    2004-01-01

    Direct write atom lithography is a technique in which nearly resonant light is used to pattern an atom beam. Nanostructures are formed when the patterned beam falls onto a substrate. We have applied this lithography scheme to a ferromagnetic element, using a 372 nm laser light standing wave to

  19. Beyond the Atom

    Science.gov (United States)

    Cox, John

    2011-08-01

    1. Introduction - the atom in the seventies; 2. The vacuum tube; 3. The new rays; 4. The new substances; 5. Disintegration; 6. A family tree; 7. Verifications and results; 8. The objective reality of molecules; 9. The new atom; Bibliography; Index.

  20. When Atoms Want

    Science.gov (United States)

    Talanquer, Vicente

    2013-01-01

    Chemistry students and teachers often explain the chemical reactivity of atoms, molecules, and chemical substances in terms of purposes or needs (e.g., atoms want or need to gain, lose, or share electrons in order to become more stable). These teleological explanations seem to have pedagogical value as they help students understand and use…

  1. Atom electron scattering

    International Nuclear Information System (INIS)

    Santoso, B.

    1976-01-01

    Green Lippmann-Schwinger functions operator representations, derivation of perturbation method using Green function and atom electron scattering, are discussed. It is concluded that by using complex coordinate places where resonances occur, can be accurately identified. The resonance can be processed further for practical purposes, for example for the separation of atom. (RUW)

  2. Atomic energy for progress

    International Nuclear Information System (INIS)

    1974-01-01

    The film discusses the functions and activities of the Philippine Atomic Energy Commission. Shown are the applications of atomic energy in research, agriculture, engineering, industry and medicine, as well as the construction of the research reactor and its inauguration by President Marcos

  3. Zeeman atomic absorption spectroscopy

    International Nuclear Information System (INIS)

    Loos-Vollebregt, M.T.C. de.

    1980-01-01

    A new method of background correction in atomic absorption spectroscopy has recently been introduced, based on the Zeeman splitting of spectral lines in a magnetic field. A theoretical analysis of the background correction capability observed in such instruments is presented. A Zeeman atomic absorption spectrometer utilizing a 50 Hz sine wave modulated magnetic field is described. (Auth.)

  4. Isotopes and atomic weights

    International Nuclear Information System (INIS)

    Zhang Qinglian

    1990-01-01

    A review of the chemical and mass spectrometric methods of determining the atomic weights of elements is presented. A, special discussion is devoted to the calibration of the mass spectrometer with highly enriched isotopes. It is illustrated by the recent work on europium. How to choose the candidate element for new atomic weight determination forms the last section of the article

  5. Atomic diffusion in stars

    CERN Document Server

    Michaud, Georges; Richer, Jacques

    2015-01-01

    This book gives an overview of atomic diffusion, a fundamental physical process, as applied to all types of stars, from the main sequence to neutron stars. The superficial abundances of stars as well as their evolution can be significantly affected. The authors show where atomic diffusion plays an essential role and how it can be implemented in modelling.  In Part I, the authors describe the tools that are required to include atomic diffusion in models of stellar interiors and atmospheres. An important role is played by the gradient of partial radiative pressure, or radiative acceleration, which is usually neglected in stellar evolution. In Part II, the authors systematically review the contribution of atomic diffusion to each evolutionary step. The dominant effects of atomic diffusion are accompanied by more subtle effects on a large number of structural properties throughout evolution. One of the goals of this book is to provide the means for the astrophysicist or graduate student to evaluate the importanc...

  6. Theoretical atomic physics

    CERN Document Server

    Friedrich, Harald

    2017-01-01

    This expanded and updated well-established textbook contains an advanced presentation of quantum mechanics adapted to the requirements of modern atomic physics. It includes topics of current interest such as semiclassical theory, chaos, atom optics and Bose-Einstein condensation in atomic gases. In order to facilitate the consolidation of the material covered, various problems are included, together with complete solutions. The emphasis on theory enables the reader to appreciate the fundamental assumptions underlying standard theoretical constructs and to embark on independent research projects. The fourth edition of Theoretical Atomic Physics contains an updated treatment of the sections involving scattering theory and near-threshold phenomena manifest in the behaviour of cold atoms (and molecules). Special attention is given to the quantization of weakly bound states just below the continuum threshold and to low-energy scattering and quantum reflection just above. Particular emphasis is laid on the fundamen...

  7. Antiprotonic-hydrogen atoms

    International Nuclear Information System (INIS)

    Batty, C.J.

    1989-07-01

    Experimental studies of antiprotonic-hydrogen atoms have recently made great progress following the commissioning of the low energy antiproton facility (LEAR) at CERN in 1983. At the same time our understanding of the atomic cascade has increased considerably through measurements of the X-ray spectra. The life history of the p-bar-p atom is considered in some detail, from the initial capture of the antiproton when stopping in hydrogen, through the atomic cascade with the emission of X-rays, to the final antiproton annihilation and production of mesons. The experiments carried out at LEAR are described and the results compared with atomic cascade calculations and predictions of strong interaction effects. (author)

  8. Atomic-scale microstructural characterization and dielectric properties of crystalline cubic pyrochlore Bi1.5MgNb1.5O7 nanoparticles synthesized by sol-gel method

    KAUST Repository

    Zhang, Yuan; Zhu, Xinhua; Zhou, Shunhua; Zhu, Jianmin; Liu, Zhiguo; Al-Kassab, Talaat

    2013-01-01

    Here, we report the atomic-scale microstructural characterization and dielectric properties of crystalline cubic pyrochlore Bi1.5MgNb 1.5O7 (BMN) nanoparticles with mean size of 70 nm, which were synthesized by sol-gel method. The crystallinity, phase formation, morphology, and surface microstructure of the BMN nanoparticles were characterized by X-ray diffraction (XRD), Raman spectra, transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM), respectively. The phase evolution of the BMN nanoparticles investigated by XRD patterns showed that uniform cubic pyrochlore BMN nanoparticles were obtained after calcination at temperature of 800 C, and their structural information was revealed by Raman spectrum. TEM images demonstrated that the BMN nanoparticles had a spherical morphology with an average particle size of 70 nm, and their crystalline nature was revealed by HRTEM images. In addition, HRTEM images also demonstrate a terrace-ledge-kink (TLK) surface structure at the edges of rough BMN nanoparticles, where the terrace was on the (100) plane, and the ledge on the (001) plane. The formation of such a TLK surface structure can be well explained by a theory of periodic bond chains. Due to the surface structural reconstruction in the BMN nanoparticles, the formation of a tetragonal structure in a rough BMN nanoparticle was also revealed by HRTEM image. The BMN nanoparticles exhibited dielectric constants of 50 at 100 kHz and 30 at 1 MHz, and the dielectric loss of 0.19 at 1 MHz. © 2013 Springer Science+Business Media Dordrecht.

  9. Atomic-scale microstructural characterization and dielectric properties of crystalline cubic pyrochlore Bi1.5MgNb1.5O7 nanoparticles synthesized by sol-gel method

    KAUST Repository

    Zhang, Yuan

    2013-12-24

    Here, we report the atomic-scale microstructural characterization and dielectric properties of crystalline cubic pyrochlore Bi1.5MgNb 1.5O7 (BMN) nanoparticles with mean size of 70 nm, which were synthesized by sol-gel method. The crystallinity, phase formation, morphology, and surface microstructure of the BMN nanoparticles were characterized by X-ray diffraction (XRD), Raman spectra, transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM), respectively. The phase evolution of the BMN nanoparticles investigated by XRD patterns showed that uniform cubic pyrochlore BMN nanoparticles were obtained after calcination at temperature of 800 C, and their structural information was revealed by Raman spectrum. TEM images demonstrated that the BMN nanoparticles had a spherical morphology with an average particle size of 70 nm, and their crystalline nature was revealed by HRTEM images. In addition, HRTEM images also demonstrate a terrace-ledge-kink (TLK) surface structure at the edges of rough BMN nanoparticles, where the terrace was on the (100) plane, and the ledge on the (001) plane. The formation of such a TLK surface structure can be well explained by a theory of periodic bond chains. Due to the surface structural reconstruction in the BMN nanoparticles, the formation of a tetragonal structure in a rough BMN nanoparticle was also revealed by HRTEM image. The BMN nanoparticles exhibited dielectric constants of 50 at 100 kHz and 30 at 1 MHz, and the dielectric loss of 0.19 at 1 MHz. © 2013 Springer Science+Business Media Dordrecht.

  10. Experimental atomic physics

    International Nuclear Information System (INIS)

    Anon.

    1985-01-01

    The experimental atomic physics program within the physics division is carried out by two groups, whose reports are given in this section. Work of the accelerator atomic physics group is centered around the 6.5-MV EN tandem accelerator; consequently, most of its research is concerned with atomic processes occurring to, or initiated by, few MeV/amu heavy ions. Other activities of this group include higher energy experiments at the Holifield Heavy Ion Research Facility (HHIRF), studies of electron and positron channeling radiation, and collaborative experiments at other institutions. The second experimental group concerns itself with lower energy atomic collision physics in support of the Fusion Energy Program. During the past year, the new Electron Cyclotron Resonance Source has been completed and some of the first data from this facility is presented. In addition to these two activities in experimental atomic physics, other chapters of this report describe progress in theoretical atomic physics, experimental plasma diagnostic development, and atomic data center compilation activities

  11. Reactivity of amino acid anions with nitrogen and oxygen atoms.

    Science.gov (United States)

    Wang, Zhe-Chen; Li, Ya-Ke; He, Sheng-Gui; Bierbaum, Veronica M

    2018-02-14

    For many decades, astronomers have searched for biological molecules, including amino acids, in the interstellar medium; this endeavor is important for investigating the hypothesis of the origin of life from space. The space environment is complex and atomic species, such as nitrogen and oxygen atoms, are widely distributed. In this work, the reactions of eight typical deprotonated amino acids (glycine, alanine, cysteine, proline, aspartic acid, histidine, tyrosine, and tryptophan) with ground state nitrogen and oxygen atoms are studied by experiment and theory. These amino acid anions do not react with nitrogen atoms. However, the reactions of these ions with oxygen atoms show an intriguing variety of ionic products and the reaction rate constants are of the order of 10 -10 cm 3 s -1 . Density functional calculations provide detailed mechanisms of the reactions, and demonstrate that spin conversion is essential for some processes. Our study provides important data and insights for understanding the kinetic and dynamic behavior of amino acids in space environments.

  12. Atomic mass spectrometry

    International Nuclear Information System (INIS)

    Sanz-Medel, A.

    1997-01-01

    The elemental inorganic analysis seems to be dominated today by techniques based on atomic spectrometry. After an evaluation of advantages and limitations of using mass analysers (ion detectors) versus conventional photomultipliers (photon detector) a brief review of the more popular techniques of the emerging Atomic Mass spectrometry is carried out. Their huge potential for inorganic trace analysis is such that in the future we could well witness how this end of the century and millennium marked the fall of the photons empire in Analytical Atomic Spectrometry. (Author)

  13. Physics of the atom

    CERN Document Server

    Wehr, Russell M; Adair, Thomas W

    1984-01-01

    The fourth edition of Physics of the Atom is designed to meet the modern need for a better understanding of the atomic age. It is an introduction suitable for students with a background in university physics and mathematical competence at the level of calculus. This book is designed to be an extension of the introductory university physics course into the realm of atomic physics. It should give students a proficiency in this field comparable to their proficiency in mechanics, heat, sound, light, and electricity.

  14. Atom trap trace analysis

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Z.-T.; Bailey, K.; Chen, C.-Y.; Du, X.; Li, Y.-M.; O' Connor, T. P.; Young, L.

    2000-05-25

    A new method of ultrasensitive trace-isotope analysis has been developed based upon the technique of laser manipulation of neutral atoms. It has been used to count individual {sup 85}Kr and {sup 81}Kr atoms present in a natural krypton sample with isotopic abundances in the range of 10{sup {minus}11} and 10{sup {minus}13}, respectively. The atom counts are free of contamination from other isotopes, elements,or molecules. The method is applicable to other trace-isotopes that can be efficiently captured with a magneto-optical trap, and has a broad range of potential applications.

  15. Division of atomic physics

    International Nuclear Information System (INIS)

    Kroell, S.

    1994-01-01

    The Division of Atomic Physics, Lund Institute of Technology (LTH), is responsible for the basic physics teaching in all subjects at LTH and for specialized teaching in Optics, Atomic Physics, Atomic and Molecular Spectroscopy and Laser Physics. The Division has research activities in basic and applied optical spectroscopy, to a large extent based on lasers. It is also part of the Physics Department, Lund University, where it forms one of eight divisions. Since the beginning of 1980 the research activities of our division have been centred around the use of lasers. The activities during the period 1991-1992 is described in this progress reports

  16. Atom trap trace analysis

    International Nuclear Information System (INIS)

    Lu, Z.-T.; Bailey, K.; Chen, C.-Y.; Du, X.; Li, Y.-M.; O'Connor, T. P.; Young, L.

    2000-01-01

    A new method of ultrasensitive trace-isotope analysis has been developed based upon the technique of laser manipulation of neutral atoms. It has been used to count individual 85 Kr and 81 Kr atoms present in a natural krypton sample with isotopic abundances in the range of 10 -11 and 10 -13 , respectively. The atom counts are free of contamination from other isotopes, elements,or molecules. The method is applicable to other trace-isotopes that can be efficiently captured with a magneto-optical trap, and has a broad range of potential applications

  17. Section of Atomic Collisions

    International Nuclear Information System (INIS)

    Berenyi, D.; Biri, S.; Gulyas, L.; Juhasz, Z.; Kover, A.; Orban, A.; Palinkas, J.; Papp, T.; Racz, R.; Ricz, S.

    2009-01-01

    The Section of Atomic Collisions is a research unit with extended activity in the field of atomic and molecular physics. Starting from the study of atomic processes at the beamlines of nuclear physics accelerators in the seventies, our research community became one of the centers of fundamental research in Atomki. We also have a strong connection to materials sciences especially along the line of electron and ion spectroscopy methods. Our present activity covers a wide range of topics from atomic collision mechanisms of fundamental interest, to the complex interactions of electrons, ions, photons and antiparticles with atoms, molecules, surfaces, and specific nanostructures. In the last few years, an increasing fraction of our present topics has become relevant for applications, e.g., molecular collision studies for the radiation therapy methods of tumors, or ion-nanostructure interactions for the future construction of small ion-focusing elements. Our section belongs to the Division of Atomic Physics. The other unit of the Division is the Section of Electron Spectroscopy and Materials Sciences. There are traditionally good connections and a strong collaboration between the groups of the two sections in many fields. From the very beginning of our research work in atomic collisions, external collaborations were of vital importance for us. We regularly organize international workshops in the field of fast ion-atom collisions and related small conferences in Debrecen from 1981. Recently, we organized the Conference on Radiation Damage in Biomolecular Systems (RADAM 2008, Debrecen), and coorganized the Conference on Elementary Processes in Atomic Systems (CEPAS 2008, Cluj). We have access to several large scale facilities in Europe within the framework of formal and informal collaborations. The next themes are in this article: Forward electron emission from energetic atomic collisions; Positron-atom collisions; Photon-atom interactions; Interference effects in electron

  18. History of early atomic clocks

    International Nuclear Information System (INIS)

    Ramsey, N.F.

    2005-01-01

    This review of the history of early atomic clocks includes early atomic beam magnetic resonance, methods of separated and successive oscillatory fields, microwave absorption, optical pumping and atomic masers. (author)

  19. Chemical reactivity of the compressed noble gas atoms and their ...

    Indian Academy of Sciences (India)

    Attempts are made to gain insights into the effect of confinement of noble gas atoms on their various reactivity indices. Systems become harder, less polarizable and difficult to excite as the compression increases. Ionization also causes similar effects. A quantum fluid density functional technique is adopted in order to study ...

  20. Microsecond atomic-scale molecular dynamics simulations of polyimides

    NARCIS (Netherlands)

    Lyulin, S.V.; Gurtovenko, A.A.; Larin, S.V.; Nazarychev, V.M.; Lyulin, A.V.

    2013-01-01

    We employ microsecond atomic-scale molecular dynamics simulations to get insight into the structural and thermal properties of heat-resistant bulk polyimides. As electrostatic interactions are essential for the polyimides considered, we propose a two-step equilibration protocol that includes long

  1. Atomic Energy Authority Bill

    International Nuclear Information System (INIS)

    Gray, J.H.N.; Stoddart, D.L.; Sinclair, R.M.; Ezra, D.

    1985-01-01

    The House, in Committee, discussed the following matters in relation to the Atomic Energy Authority Bill; financing; trading; personnel conditions of employment; public relations; organization; research programmes; fuels; energy sources; information dissemination. (U.K.)

  2. Atomic and Molecular Interactions

    International Nuclear Information System (INIS)

    2002-01-01

    The Gordon Research Conference (GRC) on Atomic and Molecular Interactions was held at Roger Williams University, Bristol, RI. Emphasis was placed on current unpublished research and discussion of the future target areas in this field

  3. Zeeman atomic absorption spectrometry

    International Nuclear Information System (INIS)

    Hadeishi, T.; McLaughlin, R.

    1978-08-01

    The design and development of a Zeeman atomic absorption spectrometer for trace element analysis are described. An instruction manual is included which details the operation, adjustment, and maintenance. Specifications and circuit diagrams are given

  4. Optics With Cold Atoms

    National Research Council Canada - National Science Library

    Hau, Lene

    2004-01-01

    .... And to test the novel atom sensor, we have built a moving-molasses magneto-optical trap in a geometry tailor-suited to the nanotube detector geometry, involving construction of a highly stable laser...

  5. Atomic Energy Control Regulations

    International Nuclear Information System (INIS)

    1992-01-01

    This is the consolidated text of the Atomic Energy Control Regulations of 17 March 1960, with amendments to 27 August 1992. The Regulations cover the licensing of nuclear facilities, radiation sources, including uranium mining, radiation protection questions, etc. (NEA)

  6. The atomic conflict

    International Nuclear Information System (INIS)

    Mez, L.

    1981-01-01

    This book provides a general view at the atomic programmes of several countries and makes an attempt to unmask the atomic industrial combines with their interlockings. The governments role is analysed as well as the atomic policy of the parties, union-trades and associations. Then, the anti-atomic movements in those countries, their forms of resistance, the resonance and the alternative proposals are presented. The countries concerned are Australia, the FRG, COMECON, Danmark, the EG, Finland, France, Great Britain, Ireland, Japan, the Netherlands, Norway, Austria, Sweden, Switzerland, Spain and the USA. For the pocket book version, Lutz Mez adds an updating epilogue which continues with the developments until springtime 1981. (orig./HP) [de

  7. Advances in atomic spectroscopy

    CERN Document Server

    Sneddon, J

    1998-01-01

    This volume continues the series'' cutting-edge reviews on developments in this field. Since its invention in the 1920s, electrostatic precipitation has been extensively used in industrial hygiene to remove dust and particulate matter from gases before entering the atmosphere. This combination of electrostatic precipitation is reported upon in the first chapter. Following this, chapter two reviews recent advances in the area of chemical modification in electrothermal atomization. Chapter three consists of a review which deal with advances and uses of electrothermal atomization atomic absorption spectrometry. Flow injection atomic spectroscopy has developed rapidly in recent years and after a general introduction, various aspects of this technique are looked at in chapter four. Finally, in chapter five the use of various spectrometric techniques for the determination of mercury are described.

  8. Atom chip gravimeter

    Science.gov (United States)

    Schubert, Christian; Abend, Sven; Gebbe, Martina; Gersemann, Matthias; Ahlers, Holger; Müntinga, Hauke; Matthias, Jonas; Sahelgozin, Maral; Herr, Waldemar; Lämmerzahl, Claus; Ertmer, Wolfgang; Rasel, Ernst

    2016-04-01

    Atom interferometry has developed into a tool for measuring rotations [1], accelerations [2], and testing fundamental physics [3]. Gravimeters based on laser cooled atoms demonstrated residual uncertainties of few microgal [2,4] and were simplified for field applications [5]. Atomic gravimeters rely on the interference of matter waves which are coherently manipulated by laser light fields. The latter can be interpreted as rulers to which the position of the atoms is compared. At three points in time separated by a free evolution, the light fields are pulsed onto the atoms. First, a coherent superposition of two momentum states is produced, then the momentum is inverted, and finally the two trajectories are recombined. Depending on the acceleration the atoms experienced, the number of atoms detected in the output ports will change. Consequently, the acceleration can be determined from the output signal. The laser cooled atoms with microkelvin temperatures used in state-of-the-art gravimeters impose limits on the accuracy [4]. Therefore, ultra-cold atoms generated by Bose-Einstein condensation and delta-kick collimation [6,7] are expected to be the key for further improvements. These sources suffered from a low flux implying an incompatible noise floor, but a competitive performance was demonstrated recently with atom chips [8]. In the compact and robust setup constructed for operation in the drop tower [6] we demonstrated all steps necessary for an atom chip gravimeter with Bose-Einstein condensates in a ground based operation. We will discuss the principle of operation, the current performance, and the perspectives to supersede the state of the art. The authors thank the QUANTUS cooperation for contributions to the drop tower project in the earlier stages. This work is supported by the German Space Agency (DLR) with funds provided by the Federal Ministry for Economic Affairs and Energy (BMWi) due to an enactment of the German Bundestag under grant numbers DLR 50WM

  9. Atoms at work

    International Nuclear Information System (INIS)

    1982-07-01

    This illustrated booklet discusses the following: atoms; fission of uranium; nuclear power plants; reactor types; plutonium (formation, properties, uses); radioactive waste (fuel cycle, reprocessing, waste management); nuclear fusion; fusion reactors; radiation; radioisotopes and their uses. (U.K.)

  10. Topics in atomic physics

    CERN Document Server

    Burkhardt, Charles E

    2006-01-01

    The study of atomic physics propelled us into the quantum age in the early twentieth century and carried us into the twenty-first century with a wealth of new and, in some cases, unexplained phenomena. Topics in Atomic Physics provides a foundation for students to begin research in modern atomic physics. It can also serve as a reference because it contains material that is not easily located in other sources. A distinguishing feature is the thorough exposition of the quantum mechanical hydrogen atom using both the traditional formulation and an alternative treatment not usually found in textbooks. The alternative treatment exploits the preeminent nature of the pure Coulomb potential and places the Lenz vector operator on an equal footing with other operators corresponding to classically conserved quantities. A number of difficult to find proofs and derivations are included as is development of operator formalism that permits facile solution of the Stark effect in hydrogen. Discussion of the classical hydrogen...

  11. Atomic Interferometry, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Vertical cavity surface emitting lasers (VCSELs) is a new technology which can be used for developing high performance laser components for atom-based sensors...

  12. Atomic bomb cataracts

    International Nuclear Information System (INIS)

    Shiraeda, Kanji

    1992-01-01

    Eye disturbance caused by atomic bomb radiation can be divided into three groups: direct injury immediately after exposure, eye lesions associated with radiation syndrome, and delayed disturbance. The crystalline lens of the eye is the most radiosensitive. Atomic bomb cataract has been investigated in a number of studies. The first section of this chapter discusses radiation cataract in terms of the incidence and characteristics. The second section deals with atomic bomb cataract, which can be diagnosed based on the four criteria: (1) opacity of the crystalline lens, (2) a history of proximal exposure, (3) lack of eye disease complicating cataract, and (4) non-exposure to radiation other than atomic bombing. The prevalence of cataract and severity of opacity are found to correlate with exposure doses and age at the time of exposure. Furthermore, it is found to correlate with distance from the hypocenter, the condition of shielding, epilation, and the presence or absence or degree of radiation syndrome. (N.K.)

  13. The Atomic Energy Control Board

    International Nuclear Information System (INIS)

    Doern, G.B.

    1976-01-01

    This study describes and assesses the regulatory and administrative processes and procedures of the Atomic Energy Control Board, the AECB. The Atomic Energy Control Act authorized the AECB to control atomic energy materials and equipment in the national interest and to participate in measures for the international control of atomic energy. The AECB is authorized to make regulations to control atomic energy materials and equipment and to make grants in support of atomic energy research. (author)

  14. Energy flux of hot atoms

    International Nuclear Information System (INIS)

    Wotzak, G.P.; Kostin, M.D.

    1976-01-01

    The process in which hot atoms collide with thermal atoms of a gas, transfer kinetic energy to them, and produce additional hot atoms is investigated. A stochastic method is used to obtain numerical results for the spatial and time dependent energy flux of hot atoms in a gas. The results indicate that in hot atom systems a front followed by an intense energy flux of hot atoms may develop

  15. Harnessing the atom

    International Nuclear Information System (INIS)

    1999-01-01

    Splitting the atom has had a major impact on the history of the latter part of the 20th century. This film depicts the many benefits - and also drawbacks - of nuclear technology, and describes how the International Atomic Energy Agency performs its various tasks. It touches on challenges such as the choice between major energy sources, growing concerns about the global climate, and prospects for nuclear arms control and disarmament

  16. Atomic Energy Act 1946

    International Nuclear Information System (INIS)

    1946-01-01

    This Act provides for the development of atomic energy in the United Kingdom and for its control. It details the duties and powers of the competent Minister, in particular his powers to obtain information on and to inspect materials, plant and processes, to control production and use of atomic energy and publication of information thereon. Also specified is the power to search for and work minerals and to acquire property. (NEA) [fr

  17. Hirshfeld atom refinement.

    Science.gov (United States)

    Capelli, Silvia C; Bürgi, Hans-Beat; Dittrich, Birger; Grabowsky, Simon; Jayatilaka, Dylan

    2014-09-01

    Hirshfeld atom refinement (HAR) is a method which determines structural parameters from single-crystal X-ray diffraction data by using an aspherical atom partitioning of tailor-made ab initio quantum mechanical molecular electron densities without any further approximation. Here the original HAR method is extended by implementing an iterative procedure of successive cycles of electron density calculations, Hirshfeld atom scattering factor calculations and structural least-squares refinements, repeated until convergence. The importance of this iterative procedure is illustrated via the example of crystalline ammonia. The new HAR method is then applied to X-ray diffraction data of the dipeptide Gly-l-Ala measured at 12, 50, 100, 150, 220 and 295 K, using Hartree-Fock and BLYP density functional theory electron densities and three different basis sets. All positions and anisotropic displacement parameters (ADPs) are freely refined without constraints or restraints - even those for hydrogen atoms. The results are systematically compared with those from neutron diffraction experiments at the temperatures 12, 50, 150 and 295 K. Although non-hydrogen-atom ADPs differ by up to three combined standard uncertainties (csu's), all other structural parameters agree within less than 2 csu's. Using our best calculations (BLYP/cc-pVTZ, recommended for organic molecules), the accuracy of determining bond lengths involving hydrogen atoms from HAR is better than 0.009 Å for temperatures of 150 K or below; for hydrogen-atom ADPs it is better than 0.006 Å(2) as judged from the mean absolute X-ray minus neutron differences. These results are among the best ever obtained. Remarkably, the precision of determining bond lengths and ADPs for the hydrogen atoms from the HAR procedure is comparable with that from the neutron measurements - an outcome which is obtained with a routinely achievable resolution of the X-ray data of 0.65 Å.

  18. Manipulating atoms with photons

    International Nuclear Information System (INIS)

    Cohen-Tannoudji, C.N.

    1998-01-01

    The article is a translation of the lecture delivered on the occasion of the 1997 Nobel Prize awarding ceremony. The physical mechanisms which allow manipulating of neutral atoms with laser photons are described. A remark is also made concerning several possible applications of ultra-cool atoms and streams of future research. The article is completed by Prof. Cohen-Tannoudji's autobiography. (Z.J.)

  19. Atoms, molecules & elements

    CERN Document Server

    Graybill, George

    2007-01-01

    Young scientists will be thrilled to explore the invisible world of atoms, molecules and elements. Our resource provides ready-to-use information and activities for remedial students using simplified language and vocabulary. Students will label each part of the atom, learn what compounds are, and explore the patterns in the periodic table of elements to find calcium (Ca), chlorine (Cl), and helium (He) through hands-on activities.

  20. Atomic bomb and leukemia

    Energy Technology Data Exchange (ETDEWEB)

    Ichimaru, M; Tomonaga, M; Amenomori, T; Matsuo, T [Nagasaki Univ. (Japan). School of Medicine

    1991-12-01

    Characteristic features of the leukemia among atomic bomb survivors were studied. Dose estimates of atomic bomb radiation were based on T65D, but the new dosimetry system DS86 was used for some analyses. The ratio of a single leukemia type to all leukemias was highest for chronic myelogenous leukemia (CML) in Hiroshima, and the occurrence of CML was thought to be most characteristic to atomic bomb radiation induced leukemia. The threshold of CML occurrence in Hiroshima is likely to be between 0.5{approx}0.09 Gy. However, the threshold of acute leukemia appears to be nearly 1 Gy. In the distribution of acute myeloid leukemia (AML) subtypes by French-American-British classification, there was no M3 case in 1 Gy or more group, although several atypical AML cases of survivors were observed. Although aplastic anemia has not increased as a late effect of the atomic bomb radiation exposure, many atypical leukemia or other myeloproliferative diseases who had been diagnosed as aplastic anemia or its related diseases have been experienced among atomic bomb survivors. Chromosome study was conducted using colony forming cells induced by hemopoietic stem cells of peripheral blood of proximal survivors. Same chromosome aberrations were observed in colony forming cells and peripheral T-cells in several atomic bomb survivors. (author).

  1. On the bosonic atoms

    Science.gov (United States)

    Amusia, M. Ya.; Chernysheva, L. V.

    2018-01-01

    We investigate ground state properties of atoms, in which substitute fermions - electrons by bosons, namely π --mesons. We perform some calculations in the frame of modified Hartree-Fock (HF) equation. The modification takes into account symmetry, instead of anti-symmetry of the pair identical bosons wave function. The modified HF approach thus enhances (doubles) the effect of self-action for the boson case. Therefore, we accordingly modify the HF equations by eliminating the self-action terms "by hand". The contribution of meson-meson and meson-nucleon non-Coulomb interaction is inessential at least for atoms with low and intermediate nuclear charge, which is our main subject. We found that the binding energy of pion negative ions A π - , pion atoms A π , and the number of extra bound pions ΔN π increases with the growth of nuclear charge Z. For e.g. Xe ΔN π = 4. As an example of a simple process with a pion atom, we consider photoionization that differs essentially from that for electron atoms. Namely, it is not monotonic decreasing from the threshold but has instead a prominent maximum above threshold. We study also elastic scattering of pions by pion atoms.

  2. Electron - atom bremsstrahlung

    International Nuclear Information System (INIS)

    Kim, L.

    1986-01-01

    Features of bremsstrahlung radiation from neutral atoms and atoms in hot dense plasmas are studied. Predictions for the distributions of electron-atom bremsstrahlung radiation for both the point-Coulomb potential and screened potentials are obtained using a classical numerical method. Results agree with exact quantum-mechanical partial-wave results for low incident electron energies in both the point-Coulomb and screened potentials. In the screened potential, the asymmetry parameter of a spectrum is reduced from the Coulomb values. The difference increases with decreasing energy and begins to oscillate at very low energies. The scaling properties of bremsstrahlung spectra and energy losses were also studied. It was found that the ratio of the radiative energy loss for positrons to that for electrons obeys a simple scaling law, being expressible fairly accurately as a function only of the quantity T 1 /Z 2 . This scaling is exact in the case of the point-Coulomb potential, both for classical bremsstrahlung and for the nonrelativistic dipole Sommerfeld formula. Bremsstrahlung from atoms in hot dense plasmas were also studied describing the atomic potentials by the temperature-and-density dependent Thomas-Fermi mode. Gaunt factors were obtained with the relativistic partial-wave method for atoms in plasmas of various densities and temperatures

  3. FAO and atomic energy

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1960-07-15

    During the past six years FAO has become more engaged in work concerned with atomic energy. In 1957 it established an Atomic Energy Branch. The new forces and new tools which have become available for use in the fight against poverty, disease and malnutrition can be of the greatest assistance in FAO's work in nearly all phases of the production, storage and distribution of food and other agricultural products. The Organization promotes their use to improve the standards of feeding, clothing and housing throughout the world. Another side of work related to atomic energy is concerned with combating contamination from the use of atomic energy for power production and other purposes. This raises considerable problems for food and agriculture, so that FAO also has a responsibility for assisting Governments in safeguarding their food and food-producing resources from contamination. FAO is essentially concerned with fostering wider knowledge of the many contributions that atomic science can make to agriculture, forestry, fisheries and nutrition. It is also concerned in assisting governments to establish sound programmes for applying atomic science in food and agriculture. One way of spreading such knowledge is through the publication of documents and reports

  4. Atomic clocks for geodesy

    Science.gov (United States)

    Mehlstäubler, Tanja E.; Grosche, Gesine; Lisdat, Christian; Schmidt, Piet O.; Denker, Heiner

    2018-06-01

    We review experimental progress on optical atomic clocks and frequency transfer, and consider the prospects of using these technologies for geodetic measurements. Today, optical atomic frequency standards have reached relative frequency inaccuracies below 10‑17, opening new fields of fundamental and applied research. The dependence of atomic frequencies on the gravitational potential makes atomic clocks ideal candidates for the search for deviations in the predictions of Einstein’s general relativity, tests of modern unifying theories and the development of new gravity field sensors. In this review, we introduce the concepts of optical atomic clocks and present the status of international clock development and comparison. Besides further improvement in stability and accuracy of today’s best clocks, a large effort is put into increasing the reliability and technological readiness for applications outside of specialized laboratories with compact, portable devices. With relative frequency uncertainties of 10‑18, comparisons of optical frequency standards are foreseen to contribute together with satellite and terrestrial data to the precise determination of fundamental height reference systems in geodesy with a resolution at the cm-level. The long-term stability of atomic standards will deliver excellent long-term height references for geodetic measurements and for the modelling and understanding of our Earth.

  5. FAO and atomic energy

    International Nuclear Information System (INIS)

    1960-01-01

    During the past six years FAO has become more engaged in work concerned with atomic energy. In 1957 it established an Atomic Energy Branch. The new forces and new tools which have become available for use in the fight against poverty, disease and malnutrition can be of the greatest assistance in FAO's work in nearly all phases of the production, storage and distribution of food and other agricultural products. The Organization promotes their use to improve the standards of feeding, clothing and housing throughout the world. Another side of work related to atomic energy is concerned with combating contamination from the use of atomic energy for power production and other purposes. This raises considerable problems for food and agriculture, so that FAO also has a responsibility for assisting Governments in safeguarding their food and food-producing resources from contamination. FAO is essentially concerned with fostering wider knowledge of the many contributions that atomic science can make to agriculture, forestry, fisheries and nutrition. It is also concerned in assisting governments to establish sound programmes for applying atomic science in food and agriculture. One way of spreading such knowledge is through the publication of documents and reports

  6. Atomic bomb and leukemia

    International Nuclear Information System (INIS)

    Ichimaru, M.; Tomonaga, M.; Amenomori, T.; Matsuo, T.

    1991-01-01

    Characteristic features of the leukemia among atomic bomb survivors were studied. Dose estimates of atomic bomb radiation were based on T65D, but the new dosimetry system DS86 was used for some analyses. The ratio of a single leukemia type to all leukemias was highest for chronic myelogenous leukemia (CML) in Hiroshima, and the occurrence of CML was thought to be most characteristic to atomic bomb radiation induced leukemia. The threshold of CML occurrence in Hiroshima is likely to be between 0.5∼0.09 Gy. However, the threshold of acute leukemia appears to be nearly 1 Gy. In the distribution of acute myeloid leukemia (AML) subtypes by French-American-British classification, there was no M3 case in 1 Gy or more group, although several atypical AML cases of survivors were observed. Although aplastic anemia has not increased as a late effect of the atomic bomb radiation exposure, many atypical leukemia or other myeloproliferative diseases who had been diagnosed as aplastic anemia or its related diseases have been experienced among atomic bomb survivors. Chromosome study was conducted using colony forming cells induced by hemopoietic stem cells of peripheral blood of proximal survivors. Same chromosome aberrations were observed in colony forming cells and peripheral T-cells in several atomic bomb survivors. (author)

  7. Atomic Scale Imaging of Nucleation and Growth Trajectories of an Interfacial Bismuth Nanodroplet.

    Science.gov (United States)

    Li, Yingxuan; Bunes, Benjamin R; Zang, Ling; Zhao, Jie; Li, Yan; Zhu, Yunqing; Wang, Chuanyi

    2016-02-23

    Because of the lack of experimental evidence, much confusion still exists on the nucleation and growth dynamics of a nanostructure, particularly of metal. The situation is even worse for nanodroplets because it is more difficult to induce the formation of a nanodroplet while imaging the dynamic process with atomic resolution. Here, taking advantage of an electron beam to induce the growth of Bi nanodroplets on a SrBi2Ta2O9 platelet under a high resolution transmission electron microscope (HRTEM), we directly observed the detailed growth pathways of Bi nanodroplets from the earliest stage of nucleation that were previously inaccessible. Atomic scale imaging reveals that the dynamics of nucleation involves a much more complex trajectory than previously predicted based on classical nucleation theory (CNT). The monatomic Bi layer was first formed in the nucleation process, which induced the formation of the prenucleated clusters. Following that, critical nuclei for the nanodroplets formed both directly from the addition of atoms to the prenucleated clusters by the classical growth process and indirectly through transformation of an intermediate liquid film based on the Stranski-Krastanov growth mode, in which the liquid film was induced by the self-assembly of the prenucleated clusters. Finally, the growth of the Bi nanodroplets advanced through the classical pathway and sudden droplet coalescence. This study allows us to visualize the critical steps in the nucleation process of an interfacial nanodroplet, which suggests a revision of the perspective of CNT.

  8. Atomic phenomena in dense plasmas

    International Nuclear Information System (INIS)

    Weisheit, J.C.

    1981-03-01

    The following chapters are included: (1) the plasma environment, (2) perturbations of atomic structure, (3) perturbations of atomic collisions, (4) formation of spectral lines, and (5) dielectronic recombination

  9. Understanding ensemble protein folding at atomic detail

    International Nuclear Information System (INIS)

    Wallin, Stefan; Shakhnovich, Eugene I

    2008-01-01

    Although far from routine, simulating the folding of specific short protein chains on the computer, at a detailed atomic level, is starting to become a reality. This remarkable progress, which has been made over the last decade or so, allows a fundamental aspect of the protein folding process to be addressed, namely its statistical nature. In order to make quantitative comparisons with experimental kinetic data a complete ensemble view of folding must be achieved, with key observables averaged over the large number of microscopically different folding trajectories available to a protein chain. Here we review recent advances in atomic-level protein folding simulations and the new insight provided by them into the protein folding process. An important element in understanding ensemble folding kinetics are methods for analyzing many separate folding trajectories, and we discuss techniques developed to condense the large amount of information contained in an ensemble of trajectories into a manageable picture of the folding process. (topical review)

  10. Chiral meta-atoms rotated by light

    International Nuclear Information System (INIS)

    Liu Mingkai; Powell, David A.; Shadrivov, Ilya V.

    2012-01-01

    We study the opto-mechanical properties of coupled chiral meta-atoms based on a pair of twisted split-ring resonators. By using a simple analytical model in conjunction with the Maxwell stress tensor, we capture insight into the mechanism and find that this structure can be used as a general prototype of subwavelength light-driven actuators over a wide range of frequencies. This coupled structure can provide a strong and tunable torque, and can support different opto-mechanical modes, including uniform rotation, periodically variable rotation and damped oscillations. Our results suggest that chiral meta-atoms are good candidates for creating sub-wavelength motors or wrenches controlled by light.

  11. Chiral meta-atoms rotated by light

    Science.gov (United States)

    Liu, Mingkai; Powell, David A.; Shadrivov, Ilya V.

    2012-07-01

    We study the opto-mechanical properties of coupled chiral meta-atoms based on a pair of twisted split-ring resonators. By using a simple analytical model in conjunction with the Maxwell stress tensor, we capture insight into the mechanism and find that this structure can be used as a general prototype of subwavelength light-driven actuators over a wide range of frequencies. This coupled structure can provide a strong and tunable torque, and can support different opto-mechanical modes, including uniform rotation, periodically variable rotation and damped oscillations. Our results suggest that chiral meta-atoms are good candidates for creating sub-wavelength motors or wrenches controlled by light.

  12. Lithiation-induced shuffling of atomic stacks

    KAUST Repository

    Nie, Anmin

    2014-09-10

    In rechargeable lithium-ion batteries, understanding the atomic-scale mechanism of Li-induced structural evolution occurring at the host electrode materials provides essential knowledge for design of new high performance electrodes. Here, we report a new crystalline-crystalline phase transition mechanism in single-crystal Zn-Sb intermetallic nanowires upon lithiation. Using in situ transmission electron microscopy, we observed that stacks of atomic planes in an intermediate hexagonal (h-)LiZnSb phase are "shuffled" to accommodate the geometrical confinement stress arising from lamellar nanodomains intercalated by lithium ions. Such atomic rearrangement arises from the anisotropic lithium diffusion and is accompanied by appearance of partial dislocations. This transient structure mediates further phase transition from h-LiZnSb to cubic (c-)Li2ZnSb, which is associated with a nearly "zero-strain" coherent interface viewed along the [001]h/[111]c directions. This study provides new mechanistic insights into complex electrochemically driven crystalline-crystalline phase transitions in lithium-ion battery electrodes and represents a noble example of atomic-level structural and interfacial rearrangements.

  13. Atomic level characterization in corrosion studies

    Science.gov (United States)

    Marcus, Philippe; Maurice, Vincent

    2017-06-01

    Atomic level characterization brings fundamental insight into the mechanisms of self-protection against corrosion of metals and alloys by oxide passive films and into how localized corrosion is initiated on passivated metal surfaces. This is illustrated in this overview with selected data obtained at the subnanometre, i.e. atomic or molecular, scale and also at the nanometre scale on single-crystal copper, nickel, chromium and stainless steel surfaces passivated in well-controlled conditions and analysed in situ and/or ex situ by scanning tunnelling microscopy/spectroscopy and atomic force microscopy. A selected example of corrosion modelling by ab initio density functional theory is also presented. The discussed aspects include the surface reconstruction induced by hydroxide adsorption and formation of two-dimensional (hydr)oxide precursors, the atomic structure, orientation and surface hydroxylation of three-dimensional ultrathin oxide passive films, the effect of grain boundaries in polycrystalline passive films acting as preferential sites of passivity breakdown, the differences in local electronic properties measured at grain boundaries of passive films and the role of step edges at the exposed surface of oxide grains on the dissolution of the passive film. This article is part of the themed issue 'The challenges of hydrogen and metals'.

  14. Atomic force microscopy of starch systems.

    Science.gov (United States)

    Zhu, Fan

    2017-09-22

    Atomic force microscopy (AFM) generates information on topography, adhesion, and elasticity of sample surface by touching with a tip. Under suitable experimental settings, AFM can image biopolymers of few nanometers. Starch is a major food and industrial component. AFM has been used to probe the morphology, properties, modifications, and interactions of starches from diverse botanical origins at both micro- and nano-structural levels. The structural information obtained by AFM supports the blocklet structure of the granules, and provides qualitative and quantitative basis for some physicochemical properties of diverse starch systems. It becomes evident that AFM can complement other microscopic techniques to provide novel structural insights for starch systems.

  15. Dreaming and insight

    Science.gov (United States)

    Edwards, Christopher L.; Ruby, Perrine M.; Malinowski, Josie E.; Bennett, Paul D.; Blagrove, Mark T.

    2013-01-01

    This paper addresses claims that dreams can be a source of personal insight. Whereas there has been anecdotal backing for such claims, there is now tangential support from findings of the facilitative effect of sleep on cognitive insight, and of REM sleep in particular on emotional memory consolidation. Furthermore, the presence in dreams of metaphorical representations of waking life indicates the possibility of novel insight as an emergent feature of such metaphorical mappings. In order to assess whether personal insight can occur as a result of the consideration of dream content, 11 dream group discussion sessions were conducted which followed the Ullman Dream Appreciation technique, one session for each of 11 participants (10 females, 1 male; mean age = 19.2 years). Self-ratings of deepened self-perception and personal gains from participation in the group sessions showed that the Ullman technique is an effective procedure for establishing connections between dream content and recent waking life experiences, although wake life sources were found for only 14% of dream report text. The mean Exploration-Insight score on the Gains from Dream Interpretation questionnaire was very high and comparable to outcomes from the well-established Hill (1996) therapist-led dream interpretation method. This score was associated between-subjects with pre-group positive Attitude Toward Dreams (ATD). The need to distinguish “aha” experiences as a result of discovering a waking life source for part of a dream, from “aha” experiences of personal insight as a result of considering dream content, is discussed. Difficulties are described in designing a control condition to which the dream report condition can be compared. PMID:24550849

  16. OpenGL Insights

    CERN Document Server

    Cozzi, Patrick

    2012-01-01

    Get Real-World Insight from Experienced Professionals in the OpenGL Community With OpenGL, OpenGL ES, and WebGL, real-time rendering is becoming available everywhere, from AAA games to mobile phones to web pages. Assembling contributions from experienced developers, vendors, researchers, and educators, OpenGL Insights presents real-world techniques for intermediate and advanced OpenGL, OpenGL ES, and WebGL developers. Go Beyond the Basics The book thoroughly covers a range of topics, including OpenGL 4.2 and recent extensions. It explains how to optimize for mobile devices, explores the design

  17. World energy insight 2011

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2011-11-15

    The World Energy Insight 2011 is the official publication of the World Energy Council. It includes interviews, articles and case studies from a distinguished panel of World Energy Council Officers, CEOs, government ministers, academics and opinion formers from all areas of the energy sector and provides perspectives from around the globe. Government, industry and NGO's offer both policy and technology perspectives. The insights within this publication add to the work that WEC is doing to provide the forum for energy leaders, along with the on-going WEC studies and programmes on Energy Policies, 2050 Energy Scenarios, Energy Resources & Technologies, Energy for Urban Innovation, Rules Of Energy Trade and Global Energy Access.

  18. Direct in situ observations of single Fe atom catalytic processes and anomalous diffusion at graphene edges

    Science.gov (United States)

    Zhao, Jiong; Deng, Qingming; Avdoshenko, Stanislav M.; Fu, Lei; Eckert, Jürgen; Rümmeli, Mark H.

    2014-01-01

    Single-atom catalysts are of great interest because of their high efficiency. In the case of chemically deposited sp2 carbon, the implementation of a single transition metal atom for growth can provide crucial insight into the formation mechanisms of graphene and carbon nanotubes. This knowledge is particularly important if we are to overcome fabrication difficulties in these materials and fully take advantage of their distinct band structures and physical properties. In this work, we present atomically resolved transmission EM in situ investigations of single Fe atoms at graphene edges. Our in situ observations show individual iron atoms diffusing along an edge either removing or adding carbon atoms (viz., catalytic action). The experimental observations of the catalytic behavior of a single Fe atom are in excellent agreement with supporting theoretical studies. In addition, the kinetics of Fe atoms at graphene edges are shown to exhibit anomalous diffusion, which again, is in agreement with our theoretical investigations. PMID:25331874

  19. UNESCO and atomic energy

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1960-01-15

    Atomic energy has been of particular concern to UNESCO virtually since the founding of this United Nations agency with the mission of promoting the advancement of science along with education and culture. UNESCO has been involved in the scientific aspects of nuclear physics - notably prior to the creation of the International Atomic Energy Agency - but it has also focussed its attention upon the educational and cultural problems of the atomic age. UNESCO's sphere of action was laid down by its 1954 General Conference which authorized its Director-General to extend full co-operation to the United Nations in atomic energy matters, with special reference to 'the urgent study of technical questions such as those involved in the effects of radioactivity on life in general, and to the dissemination of objective information concerning all aspects of the peaceful utilization of atomic energy; to study, and if necessary, to propose measures of international scope to facilitate the use of radioisotopes in research and industry'. UNESCO's first action under this resolution was to call a meeting of a committee of experts from twelve nations to study the establishment of a system of standards and regulations for the preparation, distribution, transport and utilization of radioactive isotopes and tracer molecules

  20. Insight in the outside

    NARCIS (Netherlands)

    Brongersma, H.H.; Ridder, de M.; Gildenpfennig, A.; Viitanen, M.M.

    2003-01-01

    Modern low energy ion scattering (LEIS) can provide new information on the atomic composition of both outermost surface and sub-surface layers. The wide scope of new possibilities is illustrated with results on ceramics, polymers and ultra-thin layers. Most of the results presented are difficult or

  1. Atoms in Flight: The Remarkable Connections between Atomic and Hadronic Physics

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, Stanley J.; /SLAC

    2012-02-16

    Atomic physics and hadron physics are both based on Yang Mills gauge theory; in fact, quantum electrodynamics can be regarded as the zero-color limit of quantum chromodynamics. I review a number of areas where the techniques of atomic physics provide important insight into the theory of hadrons in QCD. For example, the Dirac-Coulomb equation, which predicts the spectroscopy and structure of hydrogenic atoms, has an analog in hadron physics in the form of light-front relativistic equations of motion which give a remarkable first approximation to the spectroscopy, dynamics, and structure of light hadrons. The renormalization scale for the running coupling, which is unambiguously set in QED, leads to a method for setting the renormalization scale in QCD. The production of atoms in flight provides a method for computing the formation of hadrons at the amplitude level. Conversely, many techniques which have been developed for hadron physics, such as scaling laws, evolution equations, and light-front quantization have equal utility for atomic physics, especially in the relativistic domain. I also present a new perspective for understanding the contributions to the cosmological constant from QED and QCD.

  2. Accelerators for atomic energy research

    International Nuclear Information System (INIS)

    Shibata, Tokushi

    1999-01-01

    The research and educational activities accomplished using accelerators for atomic energy research were studied. The studied items are research subjects, facility operation, the number of master theses and doctor theses on atomic energy research using accelerators and the future role of accelerators in atomic energy research. The strategy for promotion of the accelerator facility for atomic energy research is discussed. (author)

  3. Atomic nucleus and elementary particles

    International Nuclear Information System (INIS)

    Zakrzewski, J.

    1976-01-01

    Negatively charged leptons and hadrons can be incorporated into atomic shells forming exotic atoms. Nucleon resonances and Λ hyperons can be considered as constituents of atomic nuclei. Information derived from studies of such exotic systems enriches our knowledge of both the interactions of elementary particles and of the structure of atomic nuclei. (author)

  4. Global China Insights

    NARCIS (Netherlands)

    Segers, Rien; Fischer, Ingrid

    Journal in which the Groningen Confucius Institute (GCI) shares different perspectives on China and provides insights into China from as many different aspects as possible. GCI aims to provide a full view of real China to the readers as well as featuring international and comprehensive perspectives,

  5. Global China Insights

    NARCIS (Netherlands)

    Segers, Rien; Havinga, Marieke; Fischer, Ingrid

    2013-01-01

    Journal in which the Groningen Confucius Institute (GCI) shares different perspectives on China and provides insights into China from as many different aspects as possible. GCI aims to provide a full view of real China to the readers as well as featuring international and comprehensive perspectives,

  6. Africa Insight: Submissions

    African Journals Online (AJOL)

    Author Guidelines. Africa Insight is a quarterly, peer-reviewed journal of the Africa Institute of South Africa (AISA). It is accredited by the Department of Higher ... Abstract: All articles should be accompanied by an abstract of between 100 and 125 words stating the main research problem, major findings and conclusion(s).

  7. Compilation of data from hadronic atoms

    International Nuclear Information System (INIS)

    Poth, H.

    1979-01-01

    This compilation is a survey of the existing data of hadronic atoms (pionic-atoms, kaonic-atoms, antiprotonic-atoms, sigmonic-atoms). It collects measurements of the energies, intensities and line width of X-rays from hadronic atoms. Averaged values for each hadronic atom are given and the data are summarized. The listing contains data on 58 pionic-atoms, on 54 kaonic-atoms, on 23 antiprotonic-atoms and on 20 sigmonic-atoms. (orig./HB) [de

  8. [Poor insight and psychosis].

    Science.gov (United States)

    Giotakos, O

    2017-01-01

    A variety of phenomena might be considered as reflecting impaired insight in psychosis, like failure to recognize signs, symptoms or disease, failure to derive appropriate cognitive representations, despite recognition of the disease, and misattribution of the source or cause of the disease. The unawareness of tardive dyskinesia symptoms in schizophrenic patients points that self-awareness deficits in schizophrenia may be domain specific. Poor insight is an independent phenomenological and a prevalent feature in psychotic disorders in general, and in schizophrenia in particular, but we don't know yet if delusions in schizophrenia are the result of an entirely normal attempt to account for abnormal perceptual experiences or a product of abnormal experience but of normal reasoning. The theoretical approaches regarding impaired insight include the disturbed perceptual input, the impaired linkage between thought and emotion and the breakdown of the process of self-monitoring and error checking. The inability to distinguish between internally and externally generated mental events has been described by the metarepresentation theory. This theory includes the awareness of ones' goals, which leads to disorders of willed action, the awareness of intention, which leads to movement disorders, and the awareness of intentions of others, which leads to paranoid delusions. The theory of metarepresentation implies mainly output mechanisms, like the frontal cortex, while the input mechanism implies posterior brain systems, including the parietal lobe. There are many similarities between the disturbances of awareness seen in schizophrenia and those seen as a result of known neurological impairment. Neuropsychological models of impaired insight typically attribute the disturbance to any of a variety of core deficits in the processing of information. In this respect, lack of insight is on conceptual par with alogia, apraxia or aphasia in reflecting disturbed cognitive processing. In

  9. CP violation in atoms

    International Nuclear Information System (INIS)

    Barr, S.M.

    1992-01-01

    Electric dipole moments of large atoms are an excellent tool to search for CP violation beyond the Standard Model. These tell us about the electron EDM but also about CP-violating electron-nucleon dimension-6 operators that arise from Higgs-exchange. Rapid strides are being made in searches for atomic EDMs. Limits on the electron EDM approaching the values which would be expected from Higgs-exchange mediated CP violation have been achieved. It is pointed out that in this same kind of model if tan β is large the effects in atoms of the dimension-6 e - n operators may outweigh the effect of the electron EDM. (author) 21 refs

  10. US Atomic Energy Law

    International Nuclear Information System (INIS)

    1981-01-01

    This is a new volume follows in the series supplementing the volumes 11 and 12 published in 1965 and 1966, updating the collection of Federal Acts and Executive Orders of the President of the United States of America relating to atomic energy legislation. Since the publication of volumes 11 and 12, the US Atomic Energy Act of 1954 alone has been amended 25 times, mainly as a consequence of by the Nuclear Non-Proliferation Act and the Uranium Mill Tailings Radiation Control Act, both of 1978. The Atomic Energy Act of 1954 is supplemented by a selection of the most important Federal Acts, Executive Orders of the President and Resolutions of the Congress. (orig./HSCH) [de

  11. Atomic profits, no thanks

    International Nuclear Information System (INIS)

    Bartels, W.; Dietrich, K.; Moeller, H.; Speier, C.

    1980-01-01

    The authors deal with the following topics: The secret of nuclear energy; the atom programmes of Bonn; on some arguments of the present nuclear energy discussion; how socialist countries solve the problems of nuclear energy. From the socialist point of view they discuss sociological, ideological and moral reasons for a peaceful utilization of nuclear energy. Nevertheless they refuse Bonn's atom programme because the high finance's interests concerning profit and power make it a danger. The biggest danger is said to lie in the creation of a plutonium-industry and the militaristic abuse which would be connected with it. The socialist way of utilizing atomic energy is seen by them as a way with a high feeling of responsibility towards all people and towards a guaranteed energy supply. (HSCH) [de

  12. Controlling the atom

    International Nuclear Information System (INIS)

    Mazuzan, G.T.; Walker, J.S.

    1984-01-01

    The authors trace the early history of nuclear power regulation in the US. Focusing on the Atomic Energy Commission, they describe the role of other groups that figured in the development of regulatory policies, including the Congressional Joint Committee on Atomic Energy, other federal agencies, state governments, the nuclear industry, and scientific organizations. They consider changes in public perceptions of and attitudes toward atomic energy and the dangers of radiation exposure. The basic purpose of the book is to provide the Nuclear Regulatory Commission and the general public with information on the historical antecedents and background of regulatory issues so that there will be continuity in policy decisions. The book concludes with an annotated bibliography of selected references. 19 figures

  13. DOS cones along atomic chains

    Science.gov (United States)

    Kwapiński, Tomasz

    2017-03-01

    The electron transport properties of a linear atomic chain are studied theoretically within the tight-binding Hamiltonian and the Green’s function method. Variations of the local density of states (DOS) along the chain are investigated. They are crucial in scanning tunnelling experiments and give important insight into the electron transport mechanism and charge distribution inside chains. It is found that depending on the chain parity the local DOS at the Fermi level can form cone-like structures (DOS cones) along the chain. The general condition for the local DOS oscillations is obtained and the linear behaviour of the local density function is confirmed analytically. DOS cones are characterized by a linear decay towards the chain which is in contrast to the propagation properties of charge density waves, end states and Friedel oscillations in one-dimensional systems. We find that DOS cones can appear due to non-resonant electron transport, the spin-orbit scattering or for chains fabricated on a substrate with localized electrons. It is also shown that for imperfect chains (e.g. with a reduced coupling strength between two neighboring sites) a diamond-like structure of the local DOS along the chain appears.

  14. DOS cones along atomic chains

    International Nuclear Information System (INIS)

    Kwapiński, Tomasz

    2017-01-01

    The electron transport properties of a linear atomic chain are studied theoretically within the tight-binding Hamiltonian and the Green’s function method. Variations of the local density of states (DOS) along the chain are investigated. They are crucial in scanning tunnelling experiments and give important insight into the electron transport mechanism and charge distribution inside chains. It is found that depending on the chain parity the local DOS at the Fermi level can form cone-like structures (DOS cones) along the chain. The general condition for the local DOS oscillations is obtained and the linear behaviour of the local density function is confirmed analytically. DOS cones are characterized by a linear decay towards the chain which is in contrast to the propagation properties of charge density waves, end states and Friedel oscillations in one-dimensional systems. We find that DOS cones can appear due to non-resonant electron transport, the spin–orbit scattering or for chains fabricated on a substrate with localized electrons. It is also shown that for imperfect chains (e.g. with a reduced coupling strength between two neighboring sites) a diamond-like structure of the local DOS along the chain appears. (paper)

  15. Rydberg atoms in strong fields

    International Nuclear Information System (INIS)

    Kleppner, D.; Tsimmerman, M.

    1985-01-01

    Experimental and theoretical achievements in studying Rydberg atoms in external fields are considered. Only static (or quasistatic) fields and ''one-electron'' atoms, i.e. atoms that are well described by one-electron states, are discussed. Mainly behaviour of alkali metal atoms in electric field is considered. The state of theoretical investigations for hydrogen atom in magnetic field is described, but experimental data for atoms of alkali metals are presented as an illustration. Results of the latest experimental and theoretical investigations into the structure of Rydberg atoms in strong fields are presented

  16. Atoms in Slovakia

    International Nuclear Information System (INIS)

    Danis, D.; Feik, K.; Florek, M.; Kmosena, J.; Chrapan, J.; Morovic, M.; Slugen, V.; Seliga, M.; Valovic, J.

    2006-01-01

    In this book the history of development of using of nuclear energy in the Slovak Republic as well as in the Czechoslovakia (before 1993 year) is presented. The aim of the book is to preserve the memory of the period when the creation and development of nuclear physics, technology, nuclear medicine, radioecology and energetics in Slovakia occurred - as witnessed by people who experienced this period and to adapt it to future generations. The Editorial board of the SNUS collected the views of 60 contributors and distinguished workers - Slovakian experts in nuclear science, education and technology. Calling upon a wide spectrum of experts ensured an objective historical description of the period. A huge amount of subjective views on recent decades were collected and supported by a wealth of photographic documentation. This created a synthesised reflection on the history of the 'atoms' in Slovakia. The book contains 15 tables, 192 black and white and 119 colour pictures from around the world and from places involved in the compilation of the study and with the study of atomic science in Slovakia. The main chapters are as follows: Atoms in the world, Atoms in Slovakia, Atoms in the educational system, Atoms in health services (Radiology, Nuclear medicine, Radiation protection, the Cyclotron centre of the Slovak Republic), Radioecology, Other applications of irradiation, Nuclear energetics (Electric energy in the second half of the 20 th century, NPP Bohunice, NPP Mochovce, the back-end of Nuclear energetics, Big names in Nuclear energetics in Slovakia), Chronology and an Appendix entitled 'Slovak companies in nuclear energetics'

  17. Positron-atom collisions

    International Nuclear Information System (INIS)

    Drachman, R.J.

    1984-01-01

    The past decade has seen the field of positron-atom collisions mature into an important sub-field of atomic physics. Increasingly intense positron sources are leading towards a situation in which electron and positron collision experiments will be on almost an equal footing, challenging theory to analyze their similarities and differences. The author reviews the advances made in theory, including dispersion theory, resonances, and inelastic processes. A survey of experimental progress and a brief discussion of astrophysical positronics is also included. (Auth.)

  18. Atomic Force Microscope

    Energy Technology Data Exchange (ETDEWEB)

    Day, R.D.; Russell, P.E.

    1988-12-01

    The Atomic Force Microscope (AFM) is a recently developed instrument that has achieved atomic resolution imaging of both conducting and non- conducting surfaces. Because the AFM is in the early stages of development, and because of the difficulty of building the instrument, it is currently in use in fewer than ten laboratories worldwide. It promises to be a valuable tool for obtaining information about engineering surfaces and aiding the .study of precision fabrication processes. This paper gives an overview of AFM technology and presents plans to build an instrument designed to look at engineering surfaces.

  19. Optically pumped atoms

    CERN Document Server

    Happer, William; Walker, Thad

    2010-01-01

    Covering the most important knowledge on optical pumping of atoms, this ready reference is backed by numerous examples of modelling computation for optical pumped systems. The authors show for the first time that modern scientific computing software makes it practical to analyze the full, multilevel system of optically pumped atoms. To make the discussion less abstract, the authors have illustrated key points with sections of MATLAB codes. To make most effective use of contemporary mathematical software, it is especially useful to analyze optical pumping situations in the Liouville spa

  20. Pulsed atomic soliton laser

    International Nuclear Information System (INIS)

    Carr, L.D.; Brand, J.

    2004-01-01

    It is shown that simultaneously changing the scattering length of an elongated, harmonically trapped Bose-Einstein condensate from positive to negative and inverting the axial portion of the trap, so that it becomes expulsive, results in a train of self-coherent solitonic pulses. Each pulse is itself a nondispersive attractive Bose-Einstein condensate that rapidly self-cools. The axial trap functions as a waveguide. The solitons can be made robustly stable with the right choice of trap geometry, number of atoms, and interaction strength. Theoretical and numerical evidence suggests that such a pulsed atomic soliton laser can be made in present experiments

  1. On the trends of Fukui potential and hardness potential derivatives in isolated atoms vs. atoms in molecules.

    Science.gov (United States)

    Bhattacharjee, Rituparna; Roy, Ram Kinkar

    2014-10-28

    In the present study, trends of electronic contribution to molecular electrostatic potential [Vel(r¯)(r=0)], Fukui potential [v(+)f|(r=0) and v(-)f|(r=0)] and hardness potential derivatives [Δ(+)h(k) and Δ(-)h(k)] for isolated atoms as well as atoms in molecules are investigated. The generated numerical values of these three reactivity descriptors in these two electronically different situations are critically analyzed through the relevant formalism. Values of Vel(r¯) (when r → 0, i.e., on the nucleus) are higher for atoms in molecules than that of isolated atoms. In contrast, higher values of v(+)|(r=0) and v(-)|(r=0) are observed for isolated atoms compared to the values for atoms in a molecule. However, no such regular trend is observed for the Δ(+)h(k) and Δ(-)h(k) values, which is attributed to the uncertainty in the Fukui function values of atoms in molecules. The sum of Fukui potential and the sum of hardness potential derivatives in molecules are also critically analyzed, which shows the efficacy of orbital relaxation effects in quantifying the values of these parameters. The chemical consequence of the observed trends of these descriptors in interpreting electron delocalization, electronic relaxation and non-negativity of atomic Fukui function indices is also touched upon. Several commonly used molecules containing carbon as well as heteroatoms are chosen to make the investigation more insightful.

  2. Polarized atomic beams for targets

    International Nuclear Information System (INIS)

    Grueebler, W.

    1984-01-01

    The basic principle of the production of polarized atomic hydrogen and deuterium beams are reviewed. The status of the present available polarization, density and intensity are presented. The improvement of atomic beam density by cooling the hydrogen atoms to low velocity is discussed. The possible use of polarized atomic beams as targets in storage rings is shown. It is proposed that polarized atomic beams can be used to produce polarized gas targets with high polarization and greatly improved density

  3. Atomic collisions related to atomic laser isotope separation

    International Nuclear Information System (INIS)

    Shibata, Takemasa

    1995-01-01

    Atomic collisions are important in various places in atomic vapor laser isotope separation (AVLIS). At a vaporization zone, many atomic collisions due to high density have influence on the atomic beam characteristics such as velocity distribution and metastable states' populations at a separation zone. In the separation zone, a symmetric charge transfer between the produced ions and the neutral atoms may degrade selectivity. We have measured atomic excitation temperatures of atomic beams and symmetric charge transfer cross sections for gadolinium and neodymium. Gadolinium and neodymium are both lanthanides. Nevertheless, results for gadolinium and neodymium are very different. The gadolinium atom has one 5d electron and neodymium atom has no 5d electron. It is considered that the differences are due to existence of 5d electron. (author)

  4. Spatially resolved photoionization of ultracold atoms on an atom chip

    International Nuclear Information System (INIS)

    Kraft, S.; Guenther, A.; Fortagh, J.; Zimmermann, C.

    2007-01-01

    We report on photoionization of ultracold magnetically trapped Rb atoms on an atom chip. The atoms are trapped at 5 μK in a strongly anisotropic trap. Through a hole in the chip with a diameter of 150 μm, two laser beams are focused onto a fraction of the atomic cloud. A first laser beam with a wavelength of 778 nm excites the atoms via a two-photon transition to the 5D level. With a fiber laser at 1080 nm the excited atoms are photoionized. Ionization leads to depletion of the atomic density distribution observed by absorption imaging. The resonant ionization spectrum is reported. The setup used in this experiment is suitable not only to investigate mixtures of Bose-Einstein condensates and ions but also for single-atom detection on an atom chip

  5. Comparing and contrasting nuclei and cold atomic gases

    DEFF Research Database (Denmark)

    Zinner, Nikolaj Thomas; Jensen, Aksel Stenholm

    2013-01-01

    The experimental revolution in ultracold atomic gas physics over the past decades has brought tremendous amounts of new insight to the world of degenerate quantum systems. Here we compare and contrast the developments of cold atomic gases with the physics of nuclei since many concepts, techniques......, and nomenclatures are common to both fields. However, nuclei are finite systems with interactions that are typically much more complicated than those of ultracold atomic gases. The similarities and differences must therefore be carefully addressed for a meaningful comparison and to facilitate fruitful......, interactions, and relevant length and energy scales of cold atoms and nuclei. Next we address some attempts in nuclear physics to transfer the concepts of condensates in nuclei that can in principle be built from bosonic alpha-particle constituents. We also consider Efimov physics, a prime example of nuclear...

  6. Atomic physics through astrophysics

    International Nuclear Information System (INIS)

    Dalgarno, A.

    1987-01-01

    Astronomical environments encompass an extreme range of physical conditions of temperature, density, pressure and radiation fields and unusual situations abound. In this lecture, the author describes some of the objects found in the Universe and discussed the atomic processes that occur. 45 references, 8 figures

  7. Rutherford-Bohr atom

    Science.gov (United States)

    Heilbron, J. L.

    1981-03-01

    Bohr used to introduce his attempts to explain clearly the principles of the quantum theory of the atom with an historical sketch, beginning invariably with the nuclear model proposed by Rutherford. That was sound pedagogy but bad history. The Rutherford-Bohr atom stands in the middle of a line of work initiated by J.J. Thomson and concluded by the invention of quantum mechanics. Thompson's program derived its inspiration from the peculiar emphasis on models characteristic of British physics of the 19th century. Rutherford's atom was a late product of the goals and conceptions of Victorian science. Bohr's modifications, although ultimately fatal to Thomson's program, initially gave further impetus to it. In the early 1920s the most promising approach to an adequate theory of the atom appeared to be the literal and detailed elaboration of the classical mechanics of multiply periodic orbits. The approach succeeded, demonstrating in an unexpected way the force of an argument often advanced by Thomson: because a mechanical model is richer in implications than the considerations for which it was advanced, it can suggest new directions of research that may lead to important discoveries.

  8. Deep diode atomic battery

    International Nuclear Information System (INIS)

    Anthony, T.R.; Cline, H.E.

    1977-01-01

    A deep diode atomic battery is made from a bulk semiconductor crystal containing three-dimensional arrays of columnar and lamellar P-N junctions. The battery is powered by gamma rays and x-ray emission from a radioactive source embedded in the interior of the semiconductor crystal

  9. Atoms in Astronomy.

    Science.gov (United States)

    Blanchard, Paul A.

    This booklet is part of an American Astronomical Society curriculum project designed to provide teaching materials to teachers of secondary school chemistry, physics, and earth science. A Basic Topics section discusses atomic structure, emphasizing states of matter at high temperature and spectroscopic analysis of light from the stars. A section…

  10. Atomic energy and you

    International Nuclear Information System (INIS)

    1975-01-01

    The film discusses the peaceful applications of atomic energy in agriculture, engineering, industry and medicine. Shows exploration, prospecting and mining of uraninum ores at Larap, Camarines Norte and the study of geographical conditions of the site for the proposed Nuclear Power Plant in Bataan

  11. Discovery and the atom

    International Nuclear Information System (INIS)

    1989-01-01

    ''Discovery and the Atom'' tells the story of the founding of nuclear physics. This programme looks at nuclear physics up to the discovery of the neutron in 1932. Animation explains the science of the classic experiments, such as the scattering of alpha particles by Rutherford and the discovery of the nucleus. Archive film shows the people: Lord Rutherford, James Chadwick, Marie Curie. (author)

  12. Atomically resolved tissue integration.

    Science.gov (United States)

    Karlsson, Johan; Sundell, Gustav; Thuvander, Mattias; Andersson, Martin

    2014-08-13

    In the field of biomedical technology, a critical aspect is the ability to control and understand the integration of an implantable device in living tissue. Despite the technical advances in the development of biomaterials, the elaborate interplay encompassing materials science and biology on the atomic level is not very well understood. Within implantology, anchoring a biomaterial device into bone tissue is termed osseointegration. In the most accepted theory, osseointegration is defined as an interfacial bonding between implant and bone; however, there is lack of experimental evidence to confirm this. Here we show that atom probe tomography can be used to study the implant-tissue interaction, allowing for three-dimensional atomic mapping of the interface region. Interestingly, our analyses demonstrated that direct contact between Ca atoms and the implanted titanium oxide surface is formed without the presence of a protein interlayer, which means that a pure inorganic interface is created, hence giving experimental support to the current theory of osseointegration. We foresee that this result will be of importance in the development of future biomaterials as well as in the design of in vitro evaluation techniques.

  13. Atomic transport properties

    International Nuclear Information System (INIS)

    Freyss, M.

    2015-01-01

    As presented in the first chapter of this book, atomic transport properties govern a large panel of nuclear fuel properties, from its microstructure after fabrication to its behaviour under irradiation: grain growth, oxidation, fission product release, gas bubble nucleation. The modelling of the atomic transport properties is therefore the key to understanding and predicting the material behaviour under irradiation or in storage conditions. In particular, it is noteworthy that many modelling techniques within the so-called multi-scale modelling scheme of materials make use of atomic transport data as input parameters: activation energies of diffusion, diffusion coefficients, diffusion mechanisms, all of which are then required to be known accurately. Modelling approaches that are readily used or which could be used to determine atomic transport properties of nuclear materials are reviewed here. They comprise, on the one hand, static atomistic calculations, in which the migration mechanism is fixed and the corresponding migration energy barrier is calculated, and, on the other hand, molecular dynamics calculations and kinetic Monte-Carlo simulations, for which the time evolution of the system is explicitly calculated. (author)

  14. Experimental atomic physics

    International Nuclear Information System (INIS)

    Sellin, I.A.; Elston, S.B.; Forester, J.P.; Liao, K.H.; Pegg, D.J.; Peterson, R.S.; Thoe, R.S.; Hayden, H.C.; Griffin, P.M.

    1976-01-01

    The atomic structure and collision phenomena of highly stripped ions in the range Z = 6 to 35 were studied. Charge-transfer and multiple-electron-loss cross sections were determined. Absolute x-ray-production cross sections for incident heavy ions were measured. 10 figures, 1 table

  15. Transition probabilities for atoms

    International Nuclear Information System (INIS)

    Kim, Y.K.

    1980-01-01

    Current status of advanced theoretical methods for transition probabilities for atoms and ions is discussed. An experiment on the f values of the resonance transitions of the Kr and Xe isoelectronic sequences is suggested as a test for the theoretical methods

  16. Ludwig Boltzmann: Atomic genius

    Energy Technology Data Exchange (ETDEWEB)

    Cercignani, C. [Department of Mathematics, Politecnico di Milano (Italy)]. E-mail: carcer@mate.polimi.it

    2006-09-15

    On the centenary of the death of Ludwig Boltzmann, Carlo Cercignani examines the immense contributions of the man who pioneered our understanding of the atomic nature of matter. The man who first gave a convincing explanation of the irreversibility of the macroscopic world and the symmetry of the laws of physics was the Austrian physicist Ludwig Boltzmann, who tragically committed suicide 100 years ago this month. One of the key figures in the development of the atomic theory of matter, Boltzmann's fame will be forever linked to two fundamental contributions to science. The first was his interpretation of 'entropy' as a mathematically well-defined measure of the disorder of atoms. The second was his derivation of what is now known as the Boltzmann equation, which describes the statistical properties of a gas as made up of molecules. The equation, which described for the first time how a probability can evolve with time, allowed Boltzmann to explain why macroscopic phenomena are irreversible. The key point is that while microscopic objects like atoms can behave reversibly, we never see broken coffee cups reforming because it would involve a long series of highly improbable interactions - and not because it is forbidden by the laws of physics. (U.K.)

  17. Observational Evidence for Atoms.

    Science.gov (United States)

    Jones, Edwin R., Jr.; Childers, Richard L.

    1984-01-01

    Discusses the development of the concept of atomicity and some of the many which can be used to establish its validity. Chemical evidence, evidence from crystals, Faraday's law of electrolysis, and Avogadro's number are among the areas which show how the concept originally developed from a purely philosophical idea. (JN)

  18. Coherent atomic spectroscopy

    International Nuclear Information System (INIS)

    Garton, W.R.S.

    1988-01-01

    The Argonne Spectroscopy Laboratory, initiated and advanced over several decades by F.S. Tomkins and M. Fred, has been a major international facility. A range of collaborative work in atomic spectroscopy is selected to illustrate advances in experimental physics which have been made possible by combination of the talents of Tomkins and Fred with the unique facilities of the Argonne Laboratory. (orig.)

  19. Spectra of alkali atoms

    International Nuclear Information System (INIS)

    Santoso, Budi; Arumbinang, Haryono.

    1981-01-01

    Emission spectra of alkali atoms has been determined by using spectrometer at the ultraviolet to infra red waves range. The spectra emission can be obtained by absorption spectrophotometric analysis. Comparative evaluations between experimental data and data handbook obtained by spark method were also presented. (author tr.)

  20. Atomic Particle Detection

    Energy Technology Data Exchange (ETDEWEB)

    Hellman, Hal

    1970-01-01

    This booklet tells how scientists observe the particles and electromagnetic radiation that emerges from an atomic nucleus. The equipment used falls into two general categories: counters which count each particle as it passes by, and track detectors, which make a photographic record of the particle's track.

  1. Atomic Physics 16: Sixteenth International Conference on Atomic Physics. Proceedings

    International Nuclear Information System (INIS)

    Baylis, W.E.; Drake, G.W.

    1999-01-01

    These proceedings represent papers presented at the 16th International Conference on Atomic Physics held in Windsor, Ontario, Canada, in August, 1998. The topics discussed included a wide array of subjects in atomic physics such as atom holography, alignment in atomic collisions, coulomb-interacting particles, muon experiments, x-rays from comets, atomic electron collisions in intense laser fields, spectroscopy of trapped ions, and Bose-Einstein condensates. This conference represents the single most important meeting world wide on fundamental advances in atomic physics. There were 30 papers presented at the conference,out of which 4 have been abstracted for the Energy, Science and Technology database

  2. Atomic bomb injury: radiation

    Energy Technology Data Exchange (ETDEWEB)

    Dunham, C L; Cronkite, E P; Le Roy, G V; Warren, S

    1959-01-01

    This document contains 3 reports. In the first report, the clinical diagnosis and treatment of radiation syndrome in survivors of the atomic explosions in Hiroshima and Nagasaki are described. The syndrome of acute radiation injury is applied to the symptom complex, or diseased state, which results from exposure of the whole body to the initial nuclear radiation of an atomic bomb. It is applied to injuries of the skin and subcutaneous tissues resulting from x-radiation or from contact with radioactive material. Internal radiation injury may result from the selective deposition, such as in bone or thyroid, of radioactive material that has been inhaled or absorbed through the gastrointestinal tract or wounds. Radiation syndrome is classified as very severe, severe, and mild. In the second report, a brief discussion is presented on the question of genetic effects in atomic bomb survivors in Hiroshima and Nagasaki. In the third report, a study was carried out on 205 4-1/2 year old children who had been exposed to the atomic bomb blast during the first half of intra-uterine life. Correlation between head size and mental development of the child with distance from the hypocenter, symptoms of radiation effect and type of shielding of the mother is discussed. The conclusion drawn from the present study is that central nervous system defects can be produced in the fetus by atomic bomb radiation, provided that exposure occurs within approximately 1200 meters of the hypocenter and that no effective shielding, such as concrete, protects the fetus from direct irradiation.

  3. World energy insight 2011

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2011-11-15

    The World Energy Insight 2011 is the official publication of the World Energy Council. It includes interviews, articles and case studies from a distinguished panel of World Energy Council Officers, CEOs, government ministers, academics and opinion formers from all areas of the energy sector and provides perspectives from around the globe. Government, industry and NGO's offer both policy and technology perspectives. The insights within this publication add to the work that WEC is doing to provide the forum for energy leaders, along with the on-going WEC studies and programmes on Energy Policies, 2050 Energy Scenarios, Energy Resources & Technologies, Energy for Urban Innovation, Rules Of Energy Trade and Global Energy Access.

  4. Trapped atoms along nanophotonic resonators

    Science.gov (United States)

    Fields, Brian; Kim, May; Chang, Tzu-Han; Hung, Chen-Lung

    2017-04-01

    Many-body systems subject to long-range interactions have remained a very challenging topic experimentally. Ultracold atoms trapped in extreme proximity to the surface of nanophotonic structures provides a dynamic system combining the strong atom-atom interactions mediated by guided mode photons with the exquisite control implemented with trapped atom systems. The hybrid system promises pair-wise tunability of long-range interactions between atomic pseudo spins, allowing studies of quantum magnetism extending far beyond nearest neighbor interactions. In this talk, we will discuss our current status developing high quality nanophotonic ring resonators, engineered on CMOS compatible optical chips with integrated nanostructures that, in combination with a side illuminating beam, can realize stable atom traps approximately 100nm above the surface. We will report on our progress towards loading arrays of cold atoms near the surface of these structures and studying atom-atom interaction mediated by photons with high cooperativity.

  5. The politics of insight

    OpenAIRE

    Salvi, Carola; Cristofori, Irene; Grafman, Jordan; Beeman, Mark

    2016-01-01

    Previous studies showed that liberals and conservatives differ in cognitive style. Liberals are more flexible, and tolerant of complexity and novelty, whereas conservatives are more rigid, are more resistant to change, and prefer clear answers. We administered a set of compound remote associate problems, a task extensively used to differentiate problem-solving styles (via insight or analysis). Using this task, several researches have proven that self-reports, which differentiate between insig...

  6. HPC Insights, Fall 2011

    Science.gov (United States)

    2011-01-01

    Power 6 ( Davinci ) systems. We have also made use of the Air Force Research Laboratory DSRC Altix (Hawk) and the Engineer Research and Development...the design and development of high performance gas turbine combustion systems both as a pretest analysis tool to predict static and dynamic...application while gaining insight into MATLAB’s value as an engineering tool . I would like to thank the MHPCC and the Akamai Workforce Initiative

  7. The politics of insight.

    Science.gov (United States)

    Salvi, Carola; Cristofori, Irene; Grafman, Jordan; Beeman, Mark

    2016-01-01

    Previous studies showed that liberals and conservatives differ in cognitive style. Liberals are more flexible, and tolerant of complexity and novelty, whereas conservatives are more rigid, are more resistant to change, and prefer clear answers. We administered a set of compound remote associate problems, a task extensively used to differentiate problem-solving styles (via insight or analysis). Using this task, several researches have proven that self-reports, which differentiate between insight and analytic problem-solving, are reliable and are associated with two different neural circuits. In our research we found that participants self-identifying with distinct political orientations demonstrated differences in problem-solving strategy. Liberals solved significantly more problems via insight instead of in a step-by-step analytic fashion. Our findings extend previous observations that self-identified political orientations reflect differences in cognitive styles. More specifically, we show that type of political orientation is associated with problem-solving strategy. The data converge with previous neurobehavioural and cognitive studies indicating a link between cognitive style and the psychological mechanisms that mediate political beliefs.

  8. The politics of insight

    Science.gov (United States)

    Salvi, Carola; Cristofori, Irene; Grafman, Jordan; Beeman, Mark

    2016-01-01

    Previous studies showed that liberals and conservatives differ in cognitive style. Liberals are more flexible, and tolerant of complexity and novelty, whereas conservatives are more rigid, are more resistant to change, and prefer clear answers. We administered a set of compound remote associate problems, a task extensively used to differentiate problem-solving styles (via insight or analysis). Using this task, several researches have proven that self-reports, which differentiate between insight and analytic problem-solving, are reliable and are associated with two different neural circuits. In our research we found that participants self-identifying with distinct political orientations demonstrated differences in problem-solving strategy. Liberals solved significantly more problems via insight instead of in a step-by-step analytic fashion. Our findings extend previous observations that self-identified political orientations reflect differences in cognitive styles. More specifically, we show that type of political orientation is associated with problem-solving strategy. The data converge with previous neurobehavioural and cognitive studies indicating a link between cognitive style and the psychological mechanisms that mediate political beliefs. PMID:26810954

  9. Ionization of highly excited atoms by atomic particle impact

    International Nuclear Information System (INIS)

    Smirnov, B.M.

    1976-01-01

    The ionization of a highly excited atom by a collision with an atom or molecule is considered. The theory of these processes is presented and compared with experimental data. Cross sections and ionization potential are discussed. 23 refs

  10. Single-atom lasing induced atomic self-trapping

    International Nuclear Information System (INIS)

    Salzburger, T.; Ritsch, H.

    2004-01-01

    We study atomic center of mass motion and field dynamics of a single-atom laser consisting of a single incoherently pumped free atom moving in an optical high-Q resonator. For sufficient pumping, the system starts lasing whenever the atom is close to a field antinode. If the field mode eigenfrequency is larger than the atomic transition frequency, the generated laser light attracts the atom to the field antinode and cools its motion. Using quantum Monte Carlo wave function simulations, we investigate this coupled atom-field dynamics including photon recoil and cavity decay. In the regime of strong coupling, the generated field shows strong nonclassical features like photon antibunching, and the atom is spatially confined and cooled to sub-Doppler temperatures. (author)

  11. Key insights on the structural characterization of textured Er2O3–ZrO2 nano-oxides prepared by a surfactant-free solvothermal route

    International Nuclear Information System (INIS)

    Julián-López, Beatriz; Luz, Verónica de la; Gonell, Francisco; Cordoncillo, Eloisa; López-Haro, Miguel; Calvino, Jose J.; Escribano, Purificación

    2012-01-01

    Highlights: ► Structural resolution of fluorite vs. pyrochlore in small nanocrystals. ► Simple template-free solvothermal synthesis of Er 2 O 3 –ZrO 2 nanooxides. ► Good control over size, morphology and surface properties (280 m 2 g −1 ). - Abstract: Zirconia-mixed oxides can exhibit cubic fluorite and pyrochlore structure. Their discrimination is not easy in nanooxides with a crystal size close to that of a few unit cells. In this work, high resolution transmission electron microscopy (HRTEM) has been employed to provide key insights on the structural characterization of a nanometric and porous mixed Er 2 O 3 –ZrO 2 oxide. The material was prepared by a simple template-free solvothermal route that provided nanocrystalline powders at low temperature (170 °C) with spherical morphology, and high surface area (∼280 m 2 g −1 ). The porosity was mainly originated from the assembling of organic complexing agents used in the synthesis to limit the crystal growth and to control hydrolysis and condensation reaction rates. The samples were characterized by thermal analysis, X-ray diffraction, scanning electron microscopy and N 2 adsorption measurements. A detailed study by HRTEM was conducted on microtomed samples. It was observed that the material was made of nanocrystals packed into spherical agglomerates. HRTEM simulations indicated that it is not possible to identify the pyrochlore phase in nanoparticles with diameter below 2 nm. In our samples, the analysis of the HRTEM lattice images by means of fast Fourier transform (FFT) techniques revealed well defined spots that can be assigned to different planes of a cubic fluorite-type phase, even in the raw material. Raman spectroscopy was also a powerful technique to elucidate the crystalline phase of the materials with the smallest nanoparticles. HREM and Raman results evidenced that the material is constituted, irrespective of the temperature of the final calcination step, by an ensemble of randomly

  12. What are System Dynamics Insights?

    OpenAIRE

    Stave, K.; Zimmermann, N. S.; Kim, H.

    2016-01-01

    This paper explores the concept of system dynamics insights. In our field, the term “insight” is generally understood to mean dynamic insight, that is, a deep understanding about the relationship between structure and behavior. We argue this is only one aspect of the range of insights possible from system dynamics activities, and describe a broader range of potential system dynamics insights. We also propose an initial framework for discussion that relates different types of system dynamics a...

  13. Angular momentum coupling in atom-atom collisions

    International Nuclear Information System (INIS)

    Grosser, J.

    1986-01-01

    The coupling between the electronic angular momentum and the rotating atom-atom axis in the initial or the final phase of an atom-atom collision is discussed, making use of the concepts of radial and rotational (Coriolis) coupling between different molecular states. The description is based on a limited number of well-understood approximations, and it allows an illustrative geometric representation of the transition from the body fixed to the space fixed motion of the electrons. (orig.)

  14. Hot atom chemistry of monovalent atoms in organic condensed phases

    International Nuclear Information System (INIS)

    Stoecklin, G.

    1975-01-01

    The advantages and disadvantages of hot atom studies in condensed organic phases are considered, and recent advances in condensed phase organic hot atom chemistry of recoil tritium and halogen atoms are discussed. Details are presented of the present status and understanding of liquid phase hot atom chemistry and also that of organic solids. The consequences of the Auger effect in condensed organic systems are also considered. (author)

  15. Absorption imaging of ultracold atoms on atom chips

    DEFF Research Database (Denmark)

    Smith, David A.; Aigner, Simon; Hofferberth, Sebastian

    2011-01-01

    Imaging ultracold atomic gases close to surfaces is an important tool for the detailed analysis of experiments carried out using atom chips. We describe the critical factors that need be considered, especially when the imaging beam is purposely reflected from the surface. In particular we present...... methods to measure the atom-surface distance, which is a prerequisite for magnetic field imaging and studies of atom surface-interactions....

  16. Molecular beam studies and hot atom chemistry

    International Nuclear Information System (INIS)

    Continetti, R.E.; Lee, Y.T.

    1993-01-01

    The application of the crossed molecular beam technique to the study of hot atom chemistry has provided significant insights into the dynamics of hot atom reaction. To illustrate this, two recent studies are discussed. Those are the study on the influence of translational energy in 0.6 to 1.5 eV range on endoergic reaction, and the experimental study on the detailed dynamics of elementary reaction at translational energy of 0.53 and 1.01 eV. The first example illustrates the contribution that molecular beam experiment can make in the understanding of the dynamics of endoergic substitution reaction. The second example illustrates the role that such studies can play in evaluating exact three-dimensional quantum scattering calculation and ab initio potential energy surfaces for chemical reaction. In the case of endoergic reaction of halogen substitution, it was observed that the reactive collision involved short lived collision complexes. It is suggested that energetic effect alone cannot account for the difference in cross sections, and dynamic effect most play a large role. In atom-diatom reaction, the differential cross section measurement of D+H 2 →DH+H reaction was carried out, and the results are discussed. (K.I.)

  17. The Atomic energy basic law

    International Nuclear Information System (INIS)

    1979-01-01

    The law aims to secure future energy resources, push forward progress of science and advancement of industry for welfare of the mankind and higher standard of national life by helping research, development and utilization of atomic power. Research, development and utilization of atomic power shall be limited to the peaceful purpose with emphasis laid on safety and carried on independently under democratic administration. Basic concepts and terms are defined, such as: atomic power; nuclear fuel material; nuclear raw material; reactor and radiation. The Atomic Energy Commission and the Atomic Energy Safety Commission shall be set up at the Prime Minister's Office deliberately to realize national policy of research, development and utilization of atomic power and manage democratic administration for atomic energy. The Atomic Energy Commission shall plan, consider and decide matters concerning research, development and utilization of atomic energy. The Atomic Energy Safety Commission shall plan, consider and decide issues particularly concerning safety securing among such matters. The Atomic Energy Research Institute shall be founded under the governmental supervision to perform research, experiment and other necessary affairs for development of atomic energy. The Power Reactor and Nuclear Fuel Development Corporation shall be established likewise to develop fast breeding reactor, advanced thermal reactor and nuclear fuel materials. Development of radioactive minerals, control of nuclear fuel materials and reactors and measures for patent and invention concerning atomic energy, etc. are stipulated respectively. (Okada, K.)

  18. Atomic Absorption, Atomic Fluorescence, and Flame Emission Spectrometry.

    Science.gov (United States)

    Horlick, Gary

    1984-01-01

    This review is presented in six sections. Sections focus on literature related to: (1) developments in instrumentation, measurement techniques, and procedures; (2) performance studies of flames and electrothermal atomizers; (3) applications of atomic absorption spectrometry; (4) analytical comparisons; (5) atomic fluorescence spectrometry; and (6)…

  19. Ice and Atoms: experiments with laboratory-based positron beams

    International Nuclear Information System (INIS)

    Coleman, P G

    2011-01-01

    This short review presents results of new positron and positronium (Ps) experiments in condensed matter and atomic physics, as an illustration of the satisfying variety of scientific endeavours involving positron beams which can be pursued with relatively simple apparatus in a university laboratory environment. The first of these two studies - on ice films - is an example of how positrons and Ps can provide new insights into an important system which has been widely interrogated by other techniques. The second is an example of how simple positron beam systems can still provide interesting information - here on a current interesting fundamental problem in positron atomic physics.

  20. Atomic Act amended

    International Nuclear Information System (INIS)

    Drabova, D.

    2002-01-01

    In the paper by the chairwoman of the Czech nuclear regulatory authority, the history of Czech nuclear legislation is outlined, the reasons for the amendment of the Atomic Act (Act No. 18/1997) are explained, and the amendments themselves are highlighted. The Act No. 13/2002 of 18 December 2001 is reproduced from the official Collection of Acts of the Czech Republic in the facsimile form. The following acts were thereby amended: Atomic Act No. 18/1997, Metrology Act No. 505/1990, Public Health Protection Act No. 258/2000, and Act No. 2/1969 on the Establishment of Ministries and Other Governmental Agencies of the Czech Republic. (P.A.)

  1. Atomic absorption spectrometry

    International Nuclear Information System (INIS)

    Haswell, S.J.

    1991-01-01

    Atomic absorption spectroscopy is now well established and widely used technique for the determination of trace and major elements in a wide range analyte types. There have been many advances in the atomic spectroscopy over the last decade and for this reason and to meet the demand, it was felt that there was a need for an updated book. Whilst interest in instrumental design has tended to dominate the minds of the spectrocopist, the analyst concerned with obtaining reliable and representative data, in diverse areas of application, has been diligently modifying and developing sample treatment and instrumental introduction techniques. Such methodology is de fundamental part of analysis and form the basis of the fourteen application chapters of this book. The text focuses in the main on AAS; however, the sample handling techniques described are in many cases equally applicable to ICP-OES and ICP-MS analysis. (author). refs.; figs.; tabs

  2. Elementary relativistic atoms

    International Nuclear Information System (INIS)

    Nemenov, L.

    2001-01-01

    The Coulomb interaction which occurs in the final state between two particles with opposite charges allows for creation of the bound state of these particles. In the case when particles are generated with large momentum in lab frame, the Lorentz factors of the bound state will also be much larger than one. The relativistic velocity of the atoms provides the opportunity to observe bound states of (π + μ - ), (π + π - ) and (π + K - ) with a lifetime as short as 10 -16 s, and to measure their parameters. The ultrarelativistic positronium atoms (A 2e ) allow us to observe the e.ect of superpenetration in matter, to study the effects caused by the formation time of A 2e from virtual e + e - pairs and to investigate the process of transformation of two virtual particles into the bound state

  3. Atomic assistance in 1961

    International Nuclear Information System (INIS)

    1961-01-01

    More than 100 experts provided by the International Atomic Energy Agency will be working in different parts of the world this year, assisting the Agency's Member States in building up their national programs of peaceful atomic development. The total allocation of EPTA funds to the Agency for the two-year period 1961-62 is $1 393 600 (of which approximately half is available in 1961), and is meant not only for the provision of experts and equipment but also for training fellowships and regional projects. The countries which will receive Agency assistance in the form of experts and equipment this year are: Afghanistan, Argentina, Austria, Brazil, Burma, Ceylon, Chile, the Republic of China, Denmark, Greece, Guatemala, Iceland, Indonesia, Iran, Iraq, Israel, Japan, the Republic of Korea, the Republic of Mali, Mexico, Morocco, Pakistan, the Philippines, Senegal, the Sudan, Thailand, Tunisia, Turkey, the United Arab Republic, Vietnam and Yugoslavia

  4. Meteorology and atomic energy

    International Nuclear Information System (INIS)

    Anon.

    1986-01-01

    The science of meteorology is useful in providing information that will be of assistance in the choice of favorable plant locations and in the evaluation of significant relations between meteorology and the design, construction, and operation of plant and facilities, especially those from which radioactive or toxic products could be released to the atmosphere. Under a continuing contract with the Atomic Energy Commission, the Weather Bureau has carried out this study. Some of the meteorological techniques that are available are summarized, and their applications to the possible atmospheric pollution deriving from the use of atomic energy are described. Methods and suggestions for the collection, analysis, and use of meteorological data are presented. Separate abstracts are included of 12 chapters in this publication for inclusion in the Energy Data Base

  5. Glossary of atomic terms

    International Nuclear Information System (INIS)

    1982-04-01

    This glossary, containing almost 400 terms, has been compiled to help people outside the atomic energy industry to understand what those inside it are saying. It is not intended to be a definitive dictionary of scientific or technical terms, nor does it aim to cover terms that are in general use in science and technology. A list of about 100 initials and acronyms will be found at the end. (author)

  6. Glossary of atomic terms

    International Nuclear Information System (INIS)

    1980-01-01

    This glossary (of about 400 terms) has been compiled to help people outside the atomic energy industry to understand what those inside it are saying. It is not intended to be a definitive dictionary of scientific or technical terms, nor does it aim to cover terms that are in general use in science and technology. A list of some initials and acronyms is appended. (author)

  7. Fragmentation of atomic systems

    International Nuclear Information System (INIS)

    Bohn, J.L.; Fano, U.

    1996-01-01

    We report recent progress toward a nonperturbative formulation of many-body quantum dynamics that treats all constituent particles on an equal footing. This formulation is capable of detailing the evolution of a system toward the diverse fragments into which it can break up. We illustrate the general concept with the simple example of the simultaneous excitation of both electrons in a helium atom. copyright 1996 The American Physical Society

  8. Atomic and molecular theory

    International Nuclear Information System (INIS)

    Inokuti, Mitio.

    1990-01-01

    The multifaceted role of theoretical physics in understanding the earliest stages of radiation action is discussed. Scientific topics chosen for the present discourse include photoabsorption, electron collisions, and ionic collisions, and electron transport theory, Connections of atomic and molecular physics with condensed-matter physics are also discussed. The present article includes some historical perspective and an outlook for the future. 114 refs., 3 figs

  9. Navigation with Atom Interferometers

    Science.gov (United States)

    2017-03-20

    of frequency L . This problem can be found in many standard quantum optics textbooks e.g [6]. In textbooks , the two states are usually ground and...imprinted” on the atom. Taking into account all three laser pulses, the phase difference then becomes )2()(2)0( TtTtt   , (4a

  10. Atomic emission spectroscopy

    Science.gov (United States)

    Andrew, K. H.

    1975-01-01

    The relationship between the Slater-Condon theory and the conditions within the atom as revealed by experimental data was investigated. The first spectrum of Si, Rb, Cl, Br, I, Ne, Ar, and Xe-136 and the second spectrum of As, Cu, and P were determined. Methods for assessing the phase stability of fringe counting interferometers and the design of an autoranging scanning system for digitizing the output of an infrared spectrometer and recording it on magnetic tape are described.

  11. Atomic and molecular theory

    Energy Technology Data Exchange (ETDEWEB)

    Inokuti, Mitio.

    1990-01-01

    The multifaceted role of theoretical physics in understanding the earliest stages of radiation action is discussed. Scientific topics chosen for the present discourse include photoabsorption, electron collisions, and ionic collisions, and electron transport theory, Connections of atomic and molecular physics with condensed-matter physics are also discussed. The present article includes some historical perspective and an outlook for the future. 114 refs., 3 figs.

  12. Australia's atomic conspiracy theory

    International Nuclear Information System (INIS)

    Binnie, A.

    2001-01-01

    The author questions claims by the Newcastle University historian Wayne Reynolds in his book 'Australia's Bid for the Bomb', that the impetus behind the Snowy Mountains Scheme was to provide a secure source of power for the enrichment of uranium and production of heavy water so that Australia could produce its own atomic bombs. Reynolds also argued that the Australian Atomic Energy Commission (AAEC) was set up so that Australia had a trained scientific workforce to produce plutonium for the bomb. While the book is well researched, Reynolds does not seem to understand the principles of basic science and engineering. After the Second World War, a manufacturing and industrial base with a skilled and trained workforce was needed so it could be converted to war or defence manufacturing when the need arose. This new manufacturing community would require electrical power to sustain it. Hydroelectricity and atomic energy could help provide these needs. Even though war was still raging, Prime Minister John Curtin looked ahead and set up a Department of Post-War Reconstruction. It was through this department that the Snowy Mountains Scheme would be established. Curtin did not live to see this. He died in 1945 but his successor, Ben Chifley, continued the vision. The author believes, an understanding of the science behind these developments and an appreciation of how how humans interact with each others when it comes to getting something they want is likely to give a more balanced view of the past

  13. Ghost imaging with atoms

    Science.gov (United States)

    Khakimov, R. I.; Henson, B. M.; Shin, D. K.; Hodgman, S. S.; Dall, R. G.; Baldwin, K. G. H.; Truscott, A. G.

    2016-12-01

    Ghost imaging is a counter-intuitive phenomenon—first realized in quantum optics—that enables the image of a two-dimensional object (mask) to be reconstructed using the spatio-temporal properties of a beam of particles with which it never interacts. Typically, two beams of correlated photons are used: one passes through the mask to a single-pixel (bucket) detector while the spatial profile of the other is measured by a high-resolution (multi-pixel) detector. The second beam never interacts with the mask. Neither detector can reconstruct the mask independently, but temporal cross-correlation between the two beams can be used to recover a ‘ghost’ image. Here we report the realization of ghost imaging using massive particles instead of photons. In our experiment, the two beams are formed by correlated pairs of ultracold, metastable helium atoms, which originate from s-wave scattering of two colliding Bose-Einstein condensates. We use higher-order Kapitza-Dirac scattering to generate a large number of correlated atom pairs, enabling the creation of a clear ghost image with submillimetre resolution. Future extensions of our technique could lead to the realization of ghost interference, and enable tests of Einstein-Podolsky-Rosen entanglement and Bell’s inequalities with atoms.

  14. Relativistic correlations in atoms

    International Nuclear Information System (INIS)

    Dietz, K.

    1987-01-01

    Atoms are particularly well-suited objects when it comes to testing certain concepts of many-body theories. They play a unique role in this respect because of two constructively interfering reasons: first of all, the laws describing the interactions of their constituents are the ones best known in all of Physics; secondly, their structure is comparatively simple and amenable to concise theoretical treatment. Because of these two reasons, physically motivated many-body approximation schemes, ordered in a systematic hierarchy of precision, can be carefully tested; discrepancies between theory and experiment are due to many-body effects and are never masked by uncertainties in the constituent-interaction (needless to say, the very small hadronic contributions to atomic structure is left out. Many-body effects in atoms are solely produced by the electron-electron interaction which derives from the laws of Quantum Electrodynamics or, in a very good approximation from the repulsive Coulomb potential; in the general nomenclature they are named correlations. The material is organized in two chapters: chapter 1 deals with a general introduction and discussion of g-Hartree mean-field theories, chapter 2 deals with applications. The role of vacuum fluctuations and deformations of the Dirac sea in a consistent construction of mean-fields is emphasized and their explicit form in the g-Hartree theory is given. 21 references, 5 figures, 3 tables

  15. A new atomic model

    International Nuclear Information System (INIS)

    Petrescu, Florian Ion

    2012-01-01

    The movement of an electron around the atomic nucleus has today a great importance in many engineering fields. Electronics, aeronautics, micro and nanotechnology, electrical engineering, optics, lasers, nuclear power, computing, equipment and automation, telecommunications, genetic engineering, bioengineering, special processing, modern welding, robotics, energy and electromagnetic wave field is today only a few of the many applications of electronic engineering. This book presents, shortly, a new and original relation (20 and 20') who determines the radius with that, the electron is running around the nucleus of an atom. One utilizes, two times the Lorenz relation, the Niels Bohr generalized equation, and a mass relation, which was deduced from the kinematics energy relation written in two modes: classical and Coulombian. Equalizing the mass relation with Lorenz relation one obtains a form which is a relation between the squared electron speed (v 2 ) and the radius (r). The second relation between v 2 and r was obtained by equalizing the mass of Bohr equation and the mass of Lorenz relation. For a Bohr energetically level (n=a constant value), one determines now two energetically below levels, which form an electronic layer. The author realizes by this a new atomic model, or a new quantum theory, which explains the existence of electron-clouds without spin.Writing the kinematics energy relation in two modes, classical and Coulombian one determines a relation, from which explicitely the mass of the electron is determined.

  16. A new atomic model

    Energy Technology Data Exchange (ETDEWEB)

    Petrescu, Florian Ion

    2012-07-01

    The movement of an electron around the atomic nucleus has today a great importance in many engineering fields. Electronics, aeronautics, micro and nanotechnology, electrical engineering, optics, lasers, nuclear power, computing, equipment and automation, telecommunications, genetic engineering, bioengineering, special processing, modern welding, robotics, energy and electromagnetic wave field is today only a few of the many applications of electronic engineering. This book presents, shortly, a new and original relation (20 and 20') who determines the radius with that, the electron is running around the nucleus of an atom. One utilizes, two times the Lorenz relation, the Niels Bohr generalized equation, and a mass relation, which was deduced from the kinematics energy relation written in two modes: classical and Coulombian. Equalizing the mass relation with Lorenz relation one obtains a form which is a relation between the squared electron speed (v{sup 2}) and the radius (r). The second relation between v{sup 2} and r was obtained by equalizing the mass of Bohr equation and the mass of Lorenz relation. For a Bohr energetically level (n=a constant value), one determines now two energetically below levels, which form an electronic layer. The author realizes by this a new atomic model, or a new quantum theory, which explains the existence of electron-clouds without spin.Writing the kinematics energy relation in two modes, classical and Coulombian one determines a relation, from which explicitely the mass of the electron is determined.

  17. Atomic-level computer simulation

    International Nuclear Information System (INIS)

    Adams, J.B.; Rockett, Angus; Kieffer, John; Xu Wei; Nomura, Miki; Kilian, K.A.; Richards, D.F.; Ramprasad, R.

    1994-01-01

    This paper provides a broad overview of the methods of atomic-level computer simulation. It discusses methods of modelling atomic bonding, and computer simulation methods such as energy minimization, molecular dynamics, Monte Carlo, and lattice Monte Carlo. ((orig.))

  18. Atomic inner-shell physics

    International Nuclear Information System (INIS)

    Crasemann, B.

    1985-01-01

    This book discusses: relativistic and quantum electrodynamic effects on atomic inner shells; relativistic calculation of atomic transition probabilities; many-body effects in energetic atomic transitions; Auger Electron spectrometry of core levels of atoms; experimental evaluation of inner-vacancy level energies for comparison with theory; mechanisms for energy shifts of atomic K-X rays; atomic physics research with synchrotron radiation; investigations of inner-shell states by the electron energy-loss technique at high resolution; coherence effects in electron emission by atoms; inelastic X-ray scattering including resonance phenomena; Rayleigh scattering: elastic photon scattering by bound electrons; electron-atom bremsstrahlung; X-ray and bremsstrahlung production in nuclear reactions; positron production in heavy-ion collisions, and X-ray processes in heavy-ion collisions

  19. Into the atom and beyond

    CERN Document Server

    1989-01-01

    Magnifying an atom to football pitch size. The dense nucleus, carrying almost all the atomic mass, is much smaller than the ball. The players (the electrons) would see something about the size of a marble!

  20. Atomic physics issues in fusion

    International Nuclear Information System (INIS)

    Post, D.E.

    1982-01-01

    Atomic physics issues have played a large role in controlled fusion research. A general introduction to the present role of atomic processes in both inertial and magnetic controlled fusion work is presented. (Auth.)

  1. Real and Hybrid Atomic Orbitals.

    Science.gov (United States)

    Cook, D. B.; Fowler, P. W.

    1981-01-01

    Demonstrates that the Schrodinger equation for the hydrogenlike atom separates in both spheroconal and prolate spheroidal coordinates and that these separations provide a sound theoretical basis for the real and hybrid atomic orbitals. (Author/SK)

  2. Physics of atoms and molecules

    International Nuclear Information System (INIS)

    Bransden, B.H.; Joachain, C.J.

    1983-01-01

    This book presents a unified account of the physics of atoms and molecules at a level suitable for second- and third-year undergraduate students of physics and physical chemistry. Following a brief historical introduction to the subject the authors outline the ideas and approximation methods of quantum mechanics to be used later in the book. Six chapters look at the structure of atoms and the interactions between atoms and electromagnetic radiation. The authors then move on to describe the structure of molecules and molecular spectra. Three chapters deal with atomic collisions, the scattering of electrons by atoms and the scattering of atoms by atoms. The concluding chapter considers a few of the many important applications of atomic physics within astrophysics, laser technology, and nuclear fusion. Problems are given at the end of each chapter, with hints at the solutions in an appendix. Other appendices include various special topics and derivations together with useful tables of units. (author)

  3. Capture of muons in atoms

    International Nuclear Information System (INIS)

    Vogel, P.

    1978-01-01

    A lecture is given on the general theoretical framework developed for the description of the formation of mesic atom and the initial part of the atomic cascade. Some of the observable phenomena are also discussed. 16 references

  4. New sources of cold atoms for atomic clocks

    International Nuclear Information System (INIS)

    Aucouturier, E.

    1997-01-01

    The purpose of this doctoral work is the realisation of new sources of cold cesium atoms that could be useful for the conception of a compact and high-performance atomic clock. It is based on experiences of atomic physics using light induced atomic manipulation. We present here the experiences of radiative cooling of atoms that have been realised at the Laboratoire de l'Horloge Atomique from 1993 to 1996. Firstly, we applied the techniques of radiative cooling and trapping of atoms in order to create a three-dimensional magneto-optical trap. For this first experience, we developed high quality laser sources, that were used for other experiments. We imagined a new configuration of trapping (two-dimensional magneto-optical trap) that was the basis for a cold atom source. This design gives the atoms a possibility to escape towards one particular direction. Then, we have extracted the atoms from this anisotropic trap in order to create a continuous beam of cold atoms. We have applied three methods of extraction. Firstly, the launching of atoms was performed by reducing the intensity of one of the cooling laser beams in the desired launching direction. Secondly, a frequency detuning between the two laser laser beams produced the launching of atoms by a so-called 'moving molasses'. The third method consisted in applying a static magnetic field that induced the launching of atoms in the direction of this magnetic field. At the same time, another research on cold atoms was initiated at the I.H.A. It consisted in cooling a large volume of atoms from a cell, using an isotropic light. This offers an interesting alternative to the traditional optical molasses. (author)

  5. Elementary Atom Interaction with Matter

    OpenAIRE

    Mrowczynski, Stanislaw

    1998-01-01

    The calculations of the elementary atom (the Coulomb bound state of elementary particles) interaction with the atom of matter, which are performed in the Born approximation, are reviewed. We first discuss the nonrelativistic approach and then its relativistic generalization. The cross section of the elementary atom excitation and ionization as well as the total cross section are considered. A specific selection rule, which applies for the atom formed as positronium by particle-antiparticle pa...

  6. New Equations for Calculating Principal and Fine-Structure Atomic Spectra for Single and Multi-Electron Atoms

    Energy Technology Data Exchange (ETDEWEB)

    Surdoval, Wayne A. [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Berry, David A. [National Energy Technology Lab. (NETL), Morgantown, WV (United States); Shultz, Travis R. [National Energy Technology Lab. (NETL), Morgantown, WV (United States)

    2018-03-09

    A set of equations are presented for calculating atomic principal spectral lines and fine-structure energy splits for single and multi-electron atoms. Calculated results are presented and compared to the National Institute of Science and Technology database demonstrating very good accuracy. The equations do not require fitted parameters. The only experimental parameter required is the Ionization energy for the electron of interest. The equations have comparable accuracy and broader applicability than the single electron Dirac equation. Three Appendices discuss the origin of the new equations and present calculated results. New insights into the special relativistic nature of the Dirac equation and its relationship to the new equations are presented.

  7. Rapid prototyping of versatile atom chips for atom interferometry applications.

    Science.gov (United States)

    Kasch, Brian; Squires, Matthew; Olson, Spencer; Kroese, Bethany; Imhof, Eric; Kohn, Rudolph; Stuhl, Benjamin; Schramm, Stacy; Stickney, James

    2016-05-01

    We present recent advances in the manipulation of ultracold atoms with ex-vacuo atom chips (i.e. atom chips that are not inside to the UHV chamber). Details will be presented of an experimental system that allows direct bonded copper (DBC) atom chips to be removed and replaced in minutes, requiring minimal re-optimization of parameters. This system has been used to create Bose-Einstein condensates, as well as magnetic waveguides with precisely tunable axial parameters, allowing double wells, pure harmonic confinement, and modified harmonic traps. We investigate the effects of higher order magnetic field contributions to the waveguide, and the implications for confined atom interferometry.

  8. Breaking the atom with Samson

    NARCIS (Netherlands)

    Väänänen, J.; Coecke, B.; Ong, L.; Panangaden, P.

    2013-01-01

    The dependence atom =(x,y) was introduced in [11]. Here x and y are finite sets of attributes (or variables) and the intuitive meaning of =(x,y) is that the attributes x completely (functionally) determine the attributes y. One may wonder, whether the dependence atom is truly an atom or whether it

  9. Polarizational radiation or 'atomic' bremsstrahlung

    International Nuclear Information System (INIS)

    Ya Amusia, M.

    1992-01-01

    It is demonstrated that a new kind of continuum spectrum radiation exists, where the mechanism of formation is quite different from that of ordinary bremsstrahlung. The latter originates due to slowing down of the charged projectile in the target field, while the former, called polarization radiation or 'atomic' bremsstrahlung, is a result of radiation either of the target or the projectile particles dipolarly polarized during the collision process. Not only general formulae, but also results of concrete calculations are presented. These demonstrate, that for electron-atom collisions the atomic contribution to the total bremsstrahlung spectrum becomes dominant for photon energies near and above the atomic ionization potential. As to atom-atom or ion-atom collisions, the bremsstrahlung spectrum is completely determined by the atomic contribution. The specific features of the case when the incoming particles are relativistic are discussed at length. A number of examples of colliding pairs are considered, for which the atomic bremsstrahlung process is quite essential: A bare nucleus and an atom, pair of atoms, at least one of which is excited, electron, or atom interacting with a molecule. The same mechanism is essential also in formation of radiation in nuclear and elementary particle collisions. (orig.)

  10. Magnetic trapping of Rydberg atoms

    NARCIS (Netherlands)

    Niestadt, D.; Naber, J.; Kokkelmans, S.J.J.M.F.; Spreeuw, R.J.C.

    2016-01-01

    Magnetic trapping is a well-established technique for ground state atoms. We seek to extend this concept to Rydberg atoms. Rydberg atoms are important for current visions of quantum simulators that will be used in the near future to simulate and analyse quantum problems. Current efforts in Amsterdam

  11. German atomic low meeting 2004

    International Nuclear Information System (INIS)

    Ossenbuehl, F.

    2005-01-01

    The conference report on the German atomic law meeting 2004 contains 14 contributions on the German atomic legislation within four parts: Damage precaution in the operational phase; Legal general requirements for the final disposal - considerations ''de lege lata'' and ''de lege ferenda''. Financing of the site searching by a statutory company (''Verbandsmodell''). Atomic supervision authority - federal executive administration or federal self administration?

  12. Atomic Energy Commission Act, 1963

    International Nuclear Information System (INIS)

    1963-01-01

    Promulgated in 1963, the Atomic Energy Commission Act (204) established and vested in the Ghana Atomic Energy Commission the sole responsibility for all matters relating to the peaceful uses of atomic energy in the country. Embodied in the Act are provisions relating to the powers, duties, rights and liabilities of the Commission. (EAA)

  13. Current Trends in Atomic Spectroscopy.

    Science.gov (United States)

    Wynne, James J.

    1983-01-01

    Atomic spectroscopy is the study of atoms/ions through their interaction with electromagnetic radiation, in particular, interactions in which radiation is absorbed or emitted with an internal rearrangement of the atom's electrons. Discusses nature of this field, its status and future, and how it is applied to other areas of physics. (JN)

  14. Structural characterization of CO-inhibited Mo-nitrogenase by combined application of nuclear resonance vibrational spectroscopy, extended X-ray absorption fine structure, and density functional theory: new insights into the effects of CO binding and the role of the interstitial atom.

    Science.gov (United States)

    Scott, Aubrey D; Pelmenschikov, Vladimir; Guo, Yisong; Yan, Lifen; Wang, Hongxin; George, Simon J; Dapper, Christie H; Newton, William E; Yoda, Yoshitaka; Tanaka, Yoshihito; Cramer, Stephen P

    2014-11-12

    The properties of CO-inhibited Azotobacter vinelandii (Av) Mo-nitrogenase (N2ase) have been examined by the combined application of nuclear resonance vibrational spectroscopy (NRVS), extended X-ray absorption fine structure (EXAFS), and density functional theory (DFT). Dramatic changes in the NRVS are seen under high-CO conditions, especially in a 188 cm(-1) mode associated with symmetric breathing of the central cage of the FeMo-cofactor. Similar changes are reproduced with the α-H195Q N2ase variant. In the frequency region above 450 cm(-1), additional features are seen that are assigned to Fe-CO bending and stretching modes (confirmed by (13)CO isotope shifts). The EXAFS for wild-type N2ase shows evidence for a significant cluster distortion under high-CO conditions, most dramatically in the splitting of the interaction between Mo and the shell of Fe atoms originally at 5.08 Å in the resting enzyme. A DFT model with both a terminal -CO and a partially reduced -CHO ligand bound to adjacent Fe sites is consistent with both earlier FT-IR experiments, and the present EXAFS and NRVS observations for the wild-type enzyme. Another DFT model with two terminal CO ligands on the adjacent Fe atoms yields Fe-CO bands consistent with the α-H195Q variant NRVS. The calculations also shed light on the vibrational "shake" modes of the interstitial atom inside the central cage, and their interaction with the Fe-CO modes. Implications for the CO and N2 reactivity of N2ase are discussed.

  15. Collisional alignment and orientation of atomic outer shells. Pt. 1

    International Nuclear Information System (INIS)

    Andersen, N.; Gallagher, J.W.; Hertel, I.V.

    1988-01-01

    The study of polarization of atomic radiation emitted after impact excitation has yielded an enormous wealth of detailed information on the mechanism and dynamics of collisional excitation and energy transfer, both in electron and heavy particle impact studies. In these studies, the beam of electrons, ions or fast atoms used to excite the target atoms provides a suitable quantization axis with respect to which the polarization of the fluorescent light of the excited atoms is detected. From these data information on the cross sections for the different magnetic substates of the excited atom is extracted, imparting a great deal of insight into impact mechanisms for both outer and inner shell excitation. It is our aim to provide a comprehensive review including all data available in the literature presented in a standardized and easily accessible fashion. In this review we include only alignment and orientation studies, which have a well-defined planar symmetry, i.e., in which the initial and final relative momentum of the interacting particles are well defined by differential scattering techniques. We do not make a major distinction between heavy-particle and electron impact excitation: In fact, one of our aims is to demonstrate similarities between the two fields from a technical as well as from a conceptual point of view. The review is divided into three parts: This first part (I) deals with direct excitation of atoms by electrons and fast atoms or ions. Section 2 gives an introduction to the general concepts and ideas behind this kind of study and a description of typical experimental setups. Section 3 deals with electron impact excitation of atoms, starting with the simplest case of electron-helium collisions which may be fully described by two parameters, followed by more complex cases such as electron impact excitation of hydrogen and the heavy rare gases. Section 4 describes the results for direct excitation by atomic impact. (orig./AH)

  16. Cold atoms close to surfaces

    DEFF Research Database (Denmark)

    Krüger, Peter; Wildermuth, Stephan; Hofferberth, Sebastian

    2005-01-01

    Microscopic atom optical devices integrated on atom chips allow to precisely control and manipulate ultra-cold (T atoms and Bose-Einstein condensates (BECs) close to surfaces. The relevant energy scale of a BEC is extremely small (down to ... be utilized as a sensor for variations of the potential energy of the atoms close to the surface. Here we describe how to use trapped atoms as a measurement device and analyze the performance and flexibility of the field sensor. We demonstrate microscopic magnetic imaging with simultaneous high spatial...

  17. Topics in atomic collision theory

    CERN Document Server

    Geltman, Sydney; Brueckner, Keith A

    1969-01-01

    Topics in Atomic Collision Theory originated in a course of graduate lectures given at the University of Colorado and at University College in London. It is recommended for students in physics and related fields who are interested in the application of quantum scattering theory to low-energy atomic collision phenomena. No attention is given to the electromagnetic, nuclear, or elementary particle domains. The book is organized into three parts: static field scattering, electron-atom collisions, and atom-atom collisions. These are in the order of increasing physical complexity and hence necessar

  18. Atomization process for metal powder

    International Nuclear Information System (INIS)

    Lagutkin, Stanislav; Achelis, Lydia; Sheikhaliev, Sheikhali; Uhlenwinkel, Volker; Srivastava, Vikas

    2004-01-01

    A new atomization process has been developed, which combines pressure and gas atomization. The melt leaves the pressure nozzle as a hollow thin film cone. After the pre-filming step, the melt is atomized by a gas stream delivered by a ring nozzle. The objectives of this investigation are to achieve a narrow size distribution and low specific gas consumption compared to conventional gas atomization techniques. Both lead to a higher efficiency and low costs. Tin and some alloys have been atomized successfully with this technique. The mass median diameters from different experiments are between 20 and 100 μm. Sieving analysis of the tin powder shows close particle size distributions

  19. Atomic resolution imaging of YAlO{sub 3}: Ce in the chromatic and spherical aberration corrected PICO electron microscope

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Lei [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Jülich-Aachen Research Alliance (JARA), Forschungszentrum Jülich GmbH, 52425 Jülich (Germany); Barthel, Juri [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Jülich-Aachen Research Alliance (JARA), Forschungszentrum Jülich GmbH, 52425 Jülich (Germany); Central Facility for Electron Microscopy, RWTH Aachen University, 52074 Aachen (Germany); Jia, Chun-Lin [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Jülich-Aachen Research Alliance (JARA), Forschungszentrum Jülich GmbH, 52425 Jülich (Germany); School of Electronic and Information Engineering and State Key Laboratory for Mechanical Behaviour of Materials, Xi' an Jiaotong University, Xi' an 710049 (China); Urban, Knut W., E-mail: k.urban@fz-juelich.de [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Jülich-Aachen Research Alliance (JARA), Forschungszentrum Jülich GmbH, 52425 Jülich, (Germany); School of Electronic and Information Engineering and State Key Laboratory for Mechanical Behaviour of Materials, Xi' an Jiaotong University, Xi' an 710049 (China)

    2017-05-15

    Highlights: • First time resolution of 57 pm atom separations by HRTEM with 200 keV electrons. • Quantification of the image spread by absolute matching of experiment and simulation. • An information limit of 52 pm is deduced from the determined image spread. • Substantial deviations from the bulk structure are observed for the ultra-thin sample. - Abstract: The application of combined chromatic and spherical aberration correction in high-resolution transmission electron microscopy enables a significant improvement of the spatial resolution down to 50 pm. We demonstrate that such a resolution can be achieved in practice at 200 kV. Diffractograms of images of gold nanoparticles on amorphous carbon demonstrate corresponding information transfer. The Y atom pairs in [010] oriented yttrium orthoaluminate are successfully imaged together with the Al and the O atoms. Although the 57 pm pair separation is well demonstrated separations between 55 pm and 80 pm are measured. This observation is tentatively attributed to structural relaxations and surface reconstruction in the very thin samples used. Quantification of the resolution limiting effective image spread is achieved based on an absolute match between experimental and simulated image intensity distributions.

  20. Offshore atomic power plants

    International Nuclear Information System (INIS)

    Anon.

    1975-01-01

    Various merits of offshore atomic power plants are illustrated, and their systems are assessed. The planning of the offshore atomic power plants in USA is reviewed, and the construction costs of the offshore plant in Japan were estimated. Air pollution problem may be solved by the offshore atomic power plants remarkably. Deep water at low temperature may be advantageously used as cooling water for condensers. Marine resources may be bred by building artificial habitats and by providing spring-up equipments. In the case of floating plants, the plant design can be standardized so that the construction costs may be reduced. The offshore plants can be classified into three systems, namely artificial island system, floating system and sea bottom-based system. The island system may be realized with the present level of civil engineering, but requires the development of technology for the resistance of base against earthquake and its calculation means. The floating system may be constructed with conventional power plant engineering and shipbuilding engineering, but the aseismatic stability of breakwater may be a problem to be solved. Deep water floating system and deep water submerging system are conceivable, but its realization may be difficult. The sea bottom-based system with large caissons can be realized by the present civil engineering, but the construction of the caissons, stability against earthquake and resistance to waves may be problems to be solved. The technical prediction and assessment of new plant sites for nuclear power plants have been reported by Science and Technology Agency in 1974. The construction costs of an offshore plant has been estimated by the Ministry of International Trade and Industry to be yen71,026/kW as of 1985. (Iwakiri, K.)

  1. Superconducting microtraps for ultracold atoms

    International Nuclear Information System (INIS)

    Hufnagel, C.

    2011-01-01

    Atom chips are integrated devices in which atoms and atomic clouds are stored and manipulated in miniaturized magnetic traps. State of the art fabrication technologies allow for a flexible design of the trapping potentials and consequently provide extraordinary control over atomic samples, which leads to a promising role of atom chips in the engineering and investigation of quantum mechanical systems. Naturally, for quantum mechanical applications, the atomic coherence has to be preserved. Using room temperature circuits, the coherence time of atoms close to the surface was found to be drastically limited by thermal current fluctuations in the conductors. Superconductors offer an elegant way to circumvent thermal noise and therefore present a promising option for the coherent manipulation of atomic quantum states. In this thesis trapping and manipulation of ultracold Rubidium atoms in superconducting microtraps is demonstrated. In this connection the unique properties of superconductors are used to build traps based on persistent currents, the Meissner effect and remanent magnetization. In experiment it is shown, that in superconducting atom chips, thermal magnetic field noise is significantly reduced. Furthermore it is demonstrated, that atomic samples can be employed to probe the properties of superconducting materials. (author) [de

  2. Boron atom reactions

    International Nuclear Information System (INIS)

    Estes, R.; Tabacco, M.B.; Digiuseppe, T.G.; Davidovits, P.

    1982-01-01

    The reaction rates of atomic boron with various epoxides have been measured in a flow tube apparatus. The bimolecular rate constants, in units of cm 3 molecule -1 s -1 , are: 1,2-epoxypropane (8.6 x 10 -11 ), 1,2-epoxybutane (8.8 x 10 -11 ), 1,2,3,4-diepoxybutane (5.5 x 10 -11 ), 1-chloro-2,3-epoxypropane (5.7 x 10 -11 ), and 1,2-epoxy-3,3,3-trichloropropane (1.5 x 10 -11 ). (orig.)

  3. Atom and Society

    International Nuclear Information System (INIS)

    1997-01-01

    The object of this colloquium is a thought about the means, for a democracy to adapt the process of decisions and the methods of communication with public opinion in order that the profits derived from atom go on to be larger than the risks. The questions of low doses, the nuclear safety, the underground laboratories for radioactive wastes, are studied in relation with public opinion, the question itself of public opinion is studied, the history of nuclear energy in France through the weapons and the nuclear power plants is evoked and gives an explanation of the situation of nuclear controversy. (N.C.)

  4. Chameleon induced atomic afterglow

    International Nuclear Information System (INIS)

    Brax, Philippe; Burrage, Clare

    2010-01-01

    The chameleon is a scalar field whose mass depends on the density of its environment. Chameleons are necessarily coupled to matter particles and will excite transitions between atomic energy levels in an analogous manner to photons. When created inside an optical cavity by passing a laser beam through a constant magnetic field, chameleons are trapped between the cavity walls and form a standing wave. This effect will lead to an afterglow phenomenon even when the laser beam and the magnetic field have been turned off, and could be used to probe the interactions of the chameleon field with matter.

  5. Chameleon Induced Atomic Afterglow

    CERN Document Server

    Brax, Philippe

    2010-01-01

    The chameleon is a scalar field whose mass depends on the density of its environment. Chameleons are necessarily coupled to matter particles and will excite transitions between atomic energy levels in an analogous manner to photons. When created inside an optical cavity by passing a laser beam through a constant magnetic field, chameleons are trapped between the cavity walls and form a standing wave. This effect will lead to an afterglow phenomenon even when the laser beam and the magnetic field have been turned off, and could be used to probe the interactions of the chameleon field with matter.

  6. Chameleon induced atomic afterglow

    International Nuclear Information System (INIS)

    Brax, Philippe

    2010-09-01

    The chameleon is a scalar field whose mass depends on the density of its environment. Chameleons are necessarily coupled to matter particles and will excite transitions between atomic energy levels in an analogous manner to photons. When created inside an optical cavity by passing a laser beam through a constant magnetic field, chameleons are trapped between the cavity walls and form a standing wave. This effect will lead to an afterglow phenomenon even when the laser beam and the magnetic field have been turned off, and could be used to probe the interactions of the chameleon field with matter. (orig.)

  7. Atomic mechanics of solids

    CERN Document Server

    MacPherson, A K

    1990-01-01

    This volume brings together some of the presently available theoretical techniques which will be useful in the design of solid-state materials. At present, it is impossible to specify the atomic composition of a material and its macroscopic physical properties. However, the future possibilities for such a science are being laid today. This is coming about due to the development of fast, cheap computers which will be able to undertake the calculations which are necessary.Since this field of science is fairly new, it is not yet quite clear which direction of analysis will eventually prov

  8. Amendment of Atomic Ordinance

    International Nuclear Information System (INIS)

    1987-10-01

    This amendment to the 1984 Ordinance on definitions and licences in the atomic energy field aims essentially to ensure that the commitments under the Treaty on the Non-Proliferation of Nuclear Weapons are complied with in Switzerland. The goods and articles involving uranium enrichment by the gas centrifuge process and nuclear fuel reprocessing as specified by the competent international bodies, are henceforth included in the goods subject to notification or licensing listed in the Annex to the Ordinance. Also, it is provided that a construction and an operating licence for a nuclear installation may be granted simultaneously in cases where safe operating conditions can be fully assessed. (NEA) [fr

  9. Atomic data for fusion

    Energy Technology Data Exchange (ETDEWEB)

    Hunter, H.T.; Kirkpatrick, M.I.; Alvarez, I.; Cisneros, C.; Phaneuf, R.A. (eds.); Barnett, C.F.

    1990-07-01

    This report provides a handbook of recommended cross-section and rate-coefficient data for inelastic collisions between hydrogen, helium and lithium atoms, molecules and ions, and encompasses more than 400 different reactions of primary interest in fusion research. Published experimental and theoretical data have been collected and evaluated, and the recommended data are presented in tabular, graphical and parametrized form. Processes include excitation and spectral line emission, charge exchange, ionization, stripping, dissociation and particle interchange reactions. The range of collision energies is appropriate to applications in fusion-energy research.

  10. Atomic energy and food

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1969-07-01

    International activities aimed at improving, increasing and conserving food supplies are fostered in special ways by the Joint Division of Atomic Energy in Food and Agriculture established by the Agency and the Food and Agriculture Organization of the United Nations. An examination of the processes by which food is produced and of the skills arising from nuclear techniques which are being applied is made here by Maurice Fried and Bjorn Sigurbjornsson. They are the Director and Deputy Director of the Joint Division, which is an integral part of both the Agriculture Department of FAO and of the Agency's Department of Research and Isotopes. (author)

  11. Atoms for peace awards

    International Nuclear Information System (INIS)

    1968-01-01

    In making their annual selection for 1968 the Atoms for Peace Award Trust has paid signal tribute to the Agency. Each of the three recipients has for many years contributed to its work. Sigvard Eklund, Abdus Salam and Henry DeWolf Smyth received their gold medallion and $30 000 honorarium at a ceremony in New York on 14 October this year. All of them have achieved high distinction in science, but their greatest efforts have been to make the world aware of the benefits to be gained from using nuclear knowledge for peace, health and prosperity. (author)

  12. Atomic data for fusion

    International Nuclear Information System (INIS)

    Hunter, H.T.; Kirkpatrick, M.I.; Alvarez, I.; Cisneros, C.; Phaneuf, R.A.; Barnett, C.F.

    1990-07-01

    This report provides a handbook of recommended cross-section and rate-coefficient data for inelastic collisions between hydrogen, helium and lithium atoms, molecules and ions, and encompasses more than 400 different reactions of primary interest in fusion research. Published experimental and theoretical data have been collected and evaluated, and the recommended data are presented in tabular, graphical and parametrized form. Processes include excitation and spectral line emission, charge exchange, ionization, stripping, dissociation and particle interchange reactions. The range of collision energies is appropriate to applications in fusion-energy research

  13. Chameleon induced atomic afterglow

    Energy Technology Data Exchange (ETDEWEB)

    Brax, Philippe [CEA, IPhT, CNRS, Gif-sur-Yvette (France). Inst. de Physique Theorique; Burrage, Clare [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2010-09-15

    The chameleon is a scalar field whose mass depends on the density of its environment. Chameleons are necessarily coupled to matter particles and will excite transitions between atomic energy levels in an analogous manner to photons. When created inside an optical cavity by passing a laser beam through a constant magnetic field, chameleons are trapped between the cavity walls and form a standing wave. This effect will lead to an afterglow phenomenon even when the laser beam and the magnetic field have been turned off, and could be used to probe the interactions of the chameleon field with matter. (orig.)

  14. Dynamical polarizability of atoms

    International Nuclear Information System (INIS)

    Mukhopadhyay, G.; Lundqvist, S.

    1980-07-01

    The frequency-dependent polarizability of a closed-shell atom is considered in an RPA type approximation. This is usually done using many-body perturbation theory but can also be recast into the form of equations for the density oscillations as previously shown by the authors. The latter approach is known to lead to a non-hermitian problem because of the structure of the interaction kernel. This note shows that this is also true if using the reaction matrix method. The main result is to derive the expression for the polarizability function taking into account the non-hermitian nature of the problem. (author)

  15. Electroless atomic layer deposition

    Science.gov (United States)

    Robinson, David Bruce; Cappillino, Patrick J.; Sheridan, Leah B.; Stickney, John L.; Benson, David M.

    2017-10-31

    A method of electroless atomic layer deposition is described. The method electrolessly generates a layer of sacrificial material on a surface of a first material. The method adds doses of a solution of a second material to the substrate. The method performs a galvanic exchange reaction to oxidize away the layer of the sacrificial material and deposit a layer of the second material on the surface of the first material. The method can be repeated for a plurality of iterations in order to deposit a desired thickness of the second material on the surface of the first material.

  16. Cancer in atomic bomb survivors

    International Nuclear Information System (INIS)

    Shigematsu, I.; Kagan, A.

    1986-01-01

    This book presents information on the following topics: sampling of atomic bomb survivors and method of cancer detection in Hiroshima and Nagasaki; atomic bomb dosimetry for epidemiological studies of survivors in Hiroshima and Nagasaki; tumor and tissue registries in Hiroshima and Nagasaki; the cancer registry in Nagasaki, with atomic bomb survivor data, 1973-1977; cancer mortality; methods for study of delayed health effects of a-bomb radiation; experimental radiation carcinogenesis in rodents; leukemia, multiple myeloma, and malignant lymphoma; cancer of the thyroid and salivary glands; malignant tumors in atomic bomb survivors with special reference to the pathology of stomach and lung cancer; colorectal cancer among atomic bomb survivors; breast cancer in atomic bomb survivors; and ovarian neoplasms in atomic bomb survirors

  17. Insight in seasonal affective disorder.

    Science.gov (United States)

    Ghaemi, S N; Sachs, G S; Baldassano, C F; Truman, C J

    1997-01-01

    Lack of insight complicates the evaluation and treatment of patients with psychotic and affective disorders. No studies of insight in seasonal affective disorder (SAD) have been reported. Thirty patients with SAD diagnosed by the Structured Clinical Interview for DSM-III-R but no other axis I conditions were treated short-term with light-therapy. Insight was measured with the Scale to Assess Unawareness of Mental Disorder (SUMD) as modified by the authors to assess the self-report of insight into depressive symptoms. Increasing scores (1 to 5) indicated increasing unawareness of illness (i.e., less insight). SAD patients displayed a moderate amount of insight when depressed (mean SUMD score, 2.5). When recovered, they showed no significant change in insight into past depressive symptoms (mean SUMD score, 2.8). Greater insight into current depressive symptoms correlated with more depressive symptoms on the Hamilton Rating Scale for Depression score ([HRSD] r = .35, P depressive symptoms that does not change after recovery, a result in agreement with studies of insight in psychosis and mania. Further, in SAD, increased severity of illness may be associated with increased insight into depressive symptoms, consistent with the hypothesis of depressive realism.

  18. Magnetic atom optics: mirrors, guides, traps, and chips for atoms

    Energy Technology Data Exchange (ETDEWEB)

    Hinds, E.A.; Hughes, I.G. [Sussex Centre for Optical and Atomic Physics, University of Sussex, Brighton (United Kingdom)

    1999-09-21

    For the last decade it has been possible to cool atoms to microkelvin temperatures ({approx}1 cm s{sup -1}) using a variety of optical techniques. Light beams provide the very strong frictional forces required to slow atoms from room temperature ({approx}500 m s{sup -1}). However, once the atoms are cold, the relatively weak conservative forces of static electric and magnetic fields play an important role. In our group we have been studying the interaction of cold rubidium atoms with periodically magnetized data storage media. Here we review the underlying principles of the forces acting on atoms above a suitably magnetized substrate or near current-carrying wires. We also summarize the status of experiments. These structures can be used as smooth or corrugated reflectors for controlling the trajectories of cold atoms. Alternatively, they may be used to confine atoms to a plane, a line, or a dot and in some cases to reach the quantum limit of confinement. Atoms levitated above a magnetized surface can be guided electrostatically by wires deposited on the surface. The flow and interaction of atoms in such a structure may form the basis of a new technology, 'integrated atom optics' which might ultimately be capable of realizing a quantum computer. (author)

  19. Directed Atom-by-Atom Assembly of Dopants in Silicon.

    Science.gov (United States)

    Hudak, Bethany M; Song, Jiaming; Sims, Hunter; Troparevsky, M Claudia; Humble, Travis S; Pantelides, Sokrates T; Snijders, Paul C; Lupini, Andrew R

    2018-05-17

    The ability to controllably position single atoms inside materials is key for the ultimate fabrication of devices with functionalities governed by atomic-scale properties. Single bismuth dopant atoms in silicon provide an ideal case study in view of proposals for single-dopant quantum bits. However, bismuth is the least soluble pnictogen in silicon, meaning that the dopant atoms tend to migrate out of position during sample growth. Here, we demonstrate epitaxial growth of thin silicon films doped with bismuth. We use atomic-resolution aberration-corrected imaging to view the as-grown dopant distribution and then to controllably position single dopants inside the film. Atomic-scale quantum-mechanical calculations corroborate the experimental findings. These results indicate that the scanning transmission electron microscope is of particular interest for assembling functional materials atom-by-atom because it offers both real-time monitoring and atom manipulation. We envision electron-beam manipulation of atoms inside materials as an achievable route to controllable assembly of structures of individual dopants.

  20. Cold atoms in singular potentials

    International Nuclear Information System (INIS)

    Denschlag, J. P.

    1998-09-01

    We studied both theoretically and experimentally the interaction between cold Li atoms from a magnetic-optical trap (MOT) and a charged or current-carrying wire. With this system, we were able to realize 1/r 2 and 1/r potentials in two dimensions and to observe the motion of cold atoms in both potentials. For an atom in an attractive 1/r 2 potential, there exist no stable trajectories, instead there is a characteristic class of trajectories for which atoms fall into the singularity. We were able to observe this falling of atoms into the center of the potential. Moreover, by probing the singular 1/r 2 potential with atomic clouds of varying size and temperature we extracted scaling properties of the atom-wire interaction. For very cold atoms, and very thin wires the motion of the atoms must be treated quantum mechanically. Here we predict that the absorption cross section for the 1/r 2 potential should exhibit quantum steps. These quantum steps are a manifestation of the quantum mechanical decomposition of plane waves into partial waves. For the second part of this work, we realized a two dimensional 1/r potential for cold atoms. If the potential is attractive, the atoms can be bound and follow Kepler-like orbits around the wire. The motion in the third dimension along the wire is free. We were able to exploit this property and constructed a novel cold atom guide, the 'Kepler guide'. We also demonstrated another type of atom guide (the 'side guide'), by combining the magnetic field of the wire with a homogeneous offset magnetic field. In this case, the atoms are held in a potential 'tube' on the side of the wire. The versatility, simplicity, and scaling properties of this guide make it an interesting technique. (author)

  1. Insights on STEM Careers

    Energy Technology Data Exchange (ETDEWEB)

    Wendelberger, Joanne Roth [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-11-05

    This presentation will provide career advice for individuals seeking to go beyond just having a job to building a successful career in the areas of Science, Technology, Engineering, and Mathematics. Careful planning can be used to turn a job into a springboard for professional advancement and personal satisfaction. Topics to be addressed include setting priorities, understanding career ladders, making tough choices, overcoming stereotypes and assumptions by others, networking, developing a professional identify, and balancing a career with family and other personal responsibilities. Insights on the transition from individual technical work to leadership will also be provided. The author will draw upon experiences gained in academic, industrial, and government laboratory settings, as well as extensive professional service and community involvement.

  2. Osho - Insights on sex.

    Science.gov (United States)

    Nagaraj, Anil Kumar Mysore

    2013-01-01

    Sex is a mysterious phenomenon, which has puzzled even great sages. Human beings have researched and mastered the biology of sex. But that is not all. Sex needs to be understood from the spiritual perspective too. The vision of Osho is an enlightening experience in this regard. Out of the thousands of lectures, five lectures on sex made Osho most notorious. Born into a Jain family of Madhya Pradesh, Rajneesh, who later wanted himself to be called Osho, is a great master. He has spoken volumes on a wide range of topics ranging from sex to super-consciousness. His contributions in the area of sex are based on the principles of "Tantra" which has its origin from Buddhism. This article focuses on his life and insights on sex, which if understood properly, can be a stepping stone for enlightenment.

  3. Outsourcing/Offshoring Insights

    DEFF Research Database (Denmark)

    Tate, Wendy; Bals, Lydia

    2017-01-01

    Findings: Both the geographical and governance dimensions are part of the rightshoring decision which is an important conceptual foundation for this special issue, as it invited insightful pieces on all of these phenomena (e.g. outsourcing, insourcing, offshoring, reshoring), acknowledging...... for future research out of the six papers are summarized in Table III. There is ample opportunity to further shed light on these suggestions as well as to cover parts of the “rightshoring” framework presented, that remain less covered here (e.g. insourcing and/or reshoring). Practical implications: The array...... of potential “rightshoring” options fosters clarity about the phenomena studied and their implications. The main practical implications of the six papers are summarized in Table II. Originality/value: The overall conceptual framework highlights the positioning of the final papers included into the special...

  4. Tribological improvements of carbon-carbon composites by infiltration of atomic layer deposited lubricious nanostructured ceramic oxides

    Science.gov (United States)

    Mohseni, Hamidreza

    A number of investigators have reported enhancement in oxidation and wear resistant of carbon-carbon composites (CCC) in the presence of protective coating layers. However, application of a surface and subsurface coating system that can preserve its oxidation and wear resistance along with maintaining lubricity at high temperature remains unsolved. To this end, thermodynamically stable protective oxides (ZnO/Al2O3/ZrO2) have been deposited by atomic layer deposition (ALD) to infiltrate porous CCC and graphite foams in order to improve the thermal stability and wear resistance in low and high speed sliding contacts. Characterization of microstructural evolution was achieved by using energy dispersive x-ray spectroscopy (EDS) mapping in scanning electron microscope (SEM) coupled with focused ion beam (FIB), x-ray tomography, high resolution transmission electron microscopy (HRTEM), scanning transmission electron microscopy (STEM) and X-ray diffraction (XRD). Evaluation of the tribological properties of CCC coated with abovementioned ALD thin films were performed by employing low speed pure sliding tribometer and a high speed/frequency reciprocating rig to simulate the fretting wear behavior at ambient temperature and elevated temperatures of 400°C. It was determined with x-ray tomography imaging and EDS mapping that ALD ZnO/Al2O3/ZrO2 nanolaminates and baseline ZrO2 coatings exhibited excellent conformality and pore-filling capabilities down to ˜100 microm and 1.5 mm in the porous CCC and graphite foam, respectively, which were dependent on the exposure time of the ALD precursors. XRD and HRTEM determined the crystalline phases of {0002} textured ZnO (wurtzite), amorphous Al2O3, and {101}-tetragonal ZrO2. Significant improvements up to ˜65% in the sliding and fretting wear factors were determined for the nanolaminates in comparison to the uncoated CCC. A tribochemical sliding-induced mechanically mixed layer (MML) was found to be responsible for these improvements

  5. Neuromorphic atomic switch networks.

    Directory of Open Access Journals (Sweden)

    Audrius V Avizienis

    Full Text Available Efforts to emulate the formidable information processing capabilities of the brain through neuromorphic engineering have been bolstered by recent progress in the fabrication of nonlinear, nanoscale circuit elements that exhibit synapse-like operational characteristics. However, conventional fabrication techniques are unable to efficiently generate structures with the highly complex interconnectivity found in biological neuronal networks. Here we demonstrate the physical realization of a self-assembled neuromorphic device which implements basic concepts of systems neuroscience through a hardware-based platform comprised of over a billion interconnected atomic-switch inorganic synapses embedded in a complex network of silver nanowires. Observations of network activation and passive harmonic generation demonstrate a collective response to input stimulus in agreement with recent theoretical predictions. Further, emergent behaviors unique to the complex network of atomic switches and akin to brain function are observed, namely spatially distributed memory, recurrent dynamics and the activation of feedforward subnetworks. These devices display the functional characteristics required for implementing unconventional, biologically and neurally inspired computational methodologies in a synthetic experimental system.

  6. WMO and atomic energy

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1960-09-15

    The growing interest of WMO in atomic energy was reflected in the decision of the Executive Committee in 1956 to establish a panel of experts to study the meteorological aspects of the nuclear energy. One of the major achievements of the panel, which has held two meetings since its inception, has been the preparation of a technical note treating fully the various meteorological problems resulting from the applications of the peaceful uses of atomic energy. Over the past four years, steady progress has also been made both in adapting nuclear techniques to meteorological uses and in providing advice and assistance. Much time and thought are now being devoted to the study of large-scale air mass movements, turbulent diffusion and the other meteorological processes on which the transport and gradual fall-out of radioactive debris depend. The safe location of nuclear plants and the disposal of radioactive waste are related problems in which WMO has also taken a very active interest. Another aspect of the help which WMO as an organization can provide is to help for the collection and analysis of radioactive material in the biosphere. Advances in nuclear physics have also opened up great possibilities for the use of radioactive isotopes in making meteorological and hydrometeorological measurements

  7. High speed atom source

    International Nuclear Information System (INIS)

    Hoshino, Hitoshi.

    1990-01-01

    In a high speed atom source, since the speed is not identical between ions and electrons, no sufficient neutralizing effect for ionic rays due to the mixing of the ionic rays and the electron rays can be obtained failing to obtain high speed atomic rays at high density. In view of the above, a speed control means is disposed for equalizing the speed of ions forming ionic rays and the speed of electrons forming electron rays. Further, incident angle of the electron rays and/or ionic rays to a magnet or an electrode is made variable. As a result, the relative speed between the ions and the electrons to the processing direction is reduced to zero, in which the probability of association between the ions and the electrons due to the coulomb force is increased to improve the neutralizing efficiency to easily obtain fine and high density high speed electron rays. Further, by varying the incident angle, a track capable of obtaining an ideal mixing depending on the energy of the neutralized ionic rays is formed. Since the high speed electron rays has such high density, they can be irradiated easily to the minute region of the specimen. (N.H.)

  8. Experimental validation of calculated atomic charges in ionic liquids

    Science.gov (United States)

    Fogarty, Richard M.; Matthews, Richard P.; Ashworth, Claire R.; Brandt-Talbot, Agnieszka; Palgrave, Robert G.; Bourne, Richard A.; Vander Hoogerstraete, Tom; Hunt, Patricia A.; Lovelock, Kevin R. J.

    2018-05-01

    A combination of X-ray photoelectron spectroscopy and near edge X-ray absorption fine structure spectroscopy has been used to provide an experimental measure of nitrogen atomic charges in nine ionic liquids (ILs). These experimental results are used to validate charges calculated with three computational methods: charges from electrostatic potentials using a grid-based method (ChelpG), natural bond orbital population analysis, and the atoms in molecules approach. By combining these results with those from a previous study on sulfur, we find that ChelpG charges provide the best description of the charge distribution in ILs. However, we find that ChelpG charges can lead to significant conformational dependence and therefore advise that small differences in ChelpG charges (<0.3 e) should be interpreted with care. We use these validated charges to provide physical insight into nitrogen atomic charges for the ILs probed.

  9. Emulating Molecular Orbitals and Electronic Dynamics with Ultracold Atoms

    Directory of Open Access Journals (Sweden)

    Dirk-Sören Lühmann

    2015-08-01

    Full Text Available In recent years, ultracold atoms in optical lattices have proven their great value as quantum simulators for studying strongly correlated phases and complex phenomena in solid-state systems. Here, we reveal their potential as quantum simulators for molecular physics and propose a technique to image the three-dimensional molecular orbitals with high resolution. The outstanding tunability of ultracold atoms in terms of potential and interaction offer fully adjustable model systems for gaining deep insight into the electronic structure of molecules. We study the orbitals of an artificial benzene molecule and discuss the effect of tunable interactions in its conjugated π electron system with special regard to localization and spin order. The dynamical time scales of ultracold atom simulators are on the order of milliseconds, which allows for the time-resolved monitoring of a broad range of dynamical processes. As an example, we compute the hole dynamics in the conjugated π system of the artificial benzene molecule.

  10. Insights into business student's book

    CERN Document Server

    Lannon, Michael; Trappe, Tonya

    1993-01-01

    With Challenging reading and listening texts from a range of authentic business sources, New Insights into Business will really engage your students. The thorough language and vocabulary syllabus together with the strong focus on business skills development gives students everything they need to function effectively in the workplace. New Insights into Business is a self-contained course and is also an ideal follow-on to First Insights into Business.

  11. The common elements of atomic and hadronic physics

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, Stanley J., E-mail: sjbth@slac.stanford.edu [Stanford University, SLAC National Accelerator Laboratory (United States)

    2015-08-15

    Atomic physics and hadronic physics are both governed by the Yang Mills gauge theory Lagrangian; in fact, Abelian quantum electrodynamics can be regarded as the zero-color limit of quantum chromodynamics. I review a number of areas where the techniques of atomic physics can provide important insight into hadronic eigenstates in QCD. For example, the Dirac-Coulomb equation, which predicts the spectroscopy and structure of hydrogenic atoms, has an analog in hadron physics in the form of frame-independent light-front relativistic equations of motion consistent with light-front holography which give a remarkable first approximation to the spectroscopy, dynamics, and structure of light hadrons. The production of antihydrogen in flight can provide important insight into the dynamics of hadron production in QCD at the amplitude level. The renormalization scale for the running coupling is unambiguously set in QED; an analogous procedure sets the renormalization scales in QCD, leading to scheme-independent scale-fixed predictions. Conversely, many techniques which have been developed for hadron physics, such as scaling laws, evolution equations, the quark-interchange process and light-front quantization have important applicants for atomic physics and photon science, especially in the relativistic domain.

  12. The Common Elements of Atomic and Hadronic Physics

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, Stanley J. [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2015-02-26

    Atomic physics and hadronic physics are both governed by the Yang Mills gauge theory Lagrangian; in fact, Abelian quantum electrodynamics can be regarded as the zero-color limit of quantum chromodynamics. I review a number of areas where the techniques of atomic physics can provide important insight into hadronic eigenstates in QCD. For example, the Dirac-Coulomb equation, which predicts the spectroscopy and structure of hydrogenic atoms, has an analog in hadron physics in the form of frame-independent light-front relativistic equations of motion consistent with light-front holography which give a remarkable first approximation to the spectroscopy, dynamics, and structure of light hadrons. The production of antihydrogen in flight can provide important insight into the dynamics of hadron production in QCD at the amplitude level. The renormalization scale for the running coupling is unambiguously set in QED; an analogous procedure sets the renormalization scales in QCD, leading to scheme-independent scale-fixed predictions. Conversely, many techniques which have been developed for hadron physics, such as scaling laws, evolution equations, the quark-interchange process and light-front quantization have important applicants for atomic physics and photon science, especially in the relativistic domain.

  13. Experiments with cold hydrogen atoms

    International Nuclear Information System (INIS)

    Leonas, V.B.

    1981-01-01

    Numerous investigations of atomic processes in Waseous phase on the surface with participation of ''cold'' hydrogen atoms, made during the last years, are considered. The term ''cold atom'' means the range of relative collision energies E<10 MeV (respectively 'ultracold ' atoms at E< or approximately 1 MeV) which corresponds to the range of temperatures in tens (units) of K degrees. Three main ranges of investigations where extensive experimental programs are realized are considered: study of collisional processes with hydrogen atom participation, hydrogen atoms being of astrophysical interest; study of elastic atom-molecular scattering at superlow energies and studies on the problem of condensed hydrogen. Hydrogen atoms production is realized at dissociation in non-electrode high-frequency or superhigh-frequency discharge. A method of hydrogen quantum generator and of its modifications appeared to be rather an effective means to study collisional changes of spin state of hydrogen atoms. First important results on storage and stabilization of the gas of polarized hydrogen atoms are received

  14. Reaction kinetics of hydrogen atom abstraction from isopentanol by the H atom and HO2˙ radical.

    Science.gov (United States)

    Parab, Prajakta Rajaram; Heufer, K Alexander; Fernandes, Ravi Xavier

    2018-04-25

    Isopentanol is a potential next-generation biofuel for future applications to Homogeneous Charge Compression Ignition (HCCI) engine concepts. To provide insights into the combustion behavior of isopentanol, especially to its auto-ignition behavior which is linked both to efficiency and pollutant formation in real combustion systems, detailed quantum chemical studies for crucial reactions are desired. H-Abstraction reaction rates from fuel molecules are key initiation steps for chain branching required for auto-ignition. In this study, rate constants are determined for the hydrogen atom abstraction reactions from isopentanol by the H atom and HO2˙ radical by implementing the CBS-QB3 composite method. For the treatment of the internal rotors, a Pitzer-Gwinn-like approximation is applied. On comparing the computed reaction energies, the highest exothermicity (ΔE = -46 kJ mol-1) is depicted for Hα abstraction by the H atom whereas the lowest endothermicity (ΔE = 29 kJ mol-1) is shown for the abstraction of Hα by the HO2˙ radical. The formation of hydrogen bonding is found to affect the kinetics of the H atom abstraction reactions by the HO2˙ radical. Further above 750 K, the calculated high pressure limit rate constants indicate that the total contribution from delta carbon sites (Cδ) is predominant for hydrogen atom abstraction by the H atom and HO2˙ radical.

  15. Nonspherical atomic ground-state densities and chemical deformation densities from x-ray scattering

    International Nuclear Information System (INIS)

    Ruedenberg, K.; Schwarz, W.H.E.

    1990-01-01

    Presuming that chemical insight can be gained from the difference between the molecular electron density and the superposition of the ground-state densities of the atoms in a molecule, it is pointed out that, for atoms with degenerate ground states, an unpromoted ''atom in a molecule'' is represented by a specific ensemble of the degenerate atomic ground-state wave functions and that this ensemble is determined by the anisotropic local surroundings. The resulting atomic density contributions are termed oriented ground state densities, and the corresponding density difference is called the chemical deformation density. The constraints implied by this conceptual approach for the atomic density contributions are formulated and a method is developed for determining them from x-ray scattering data. The electron density of the appropriate promolecule and its x-ray scattering are derived, the determination of the parameters of the promolecule is outlined, and the chemical deformation density is formulated

  16. Latest Insights on Adenovirus Structure and Assembly

    Directory of Open Access Journals (Sweden)

    Carmen San Martín

    2012-05-01

    Full Text Available Adenovirus (AdV capsid organization is considerably complex, not only because of its large size (~950 Å and triangulation number (pseudo T = 25, but also because it contains four types of minor proteins in specialized locations modulating the quasi-equivalent icosahedral interactions. Up until 2009, only its major components (hexon, penton, and fiber had separately been described in atomic detail. Their relationships within the virion, and the location of minor coat proteins, were inferred from combining the known crystal structures with increasingly more detailed cryo-electron microscopy (cryoEM maps. There was no structural information on assembly intermediates. Later on that year, two reports described the structural differences between the mature and immature adenoviral particle, starting to shed light on the different stages of viral assembly, and giving further insights into the roles of core and minor coat proteins during morphogenesis [1,2]. Finally, in 2010, two papers describing the atomic resolution structure of the complete virion appeared [3,4]. These reports represent a veritable tour de force for two structural biology techniques: X-ray crystallography and cryoEM, as this is the largest macromolecular complex solved at high resolution by either of them. In particular, the cryoEM analysis provided an unprecedented clear picture of the complex protein networks shaping the icosahedral shell. Here I review these latest developments in the field of AdV structural studies.

  17. Insight in schizophrenia: a review.

    Science.gov (United States)

    Dam, Jesper

    2006-01-01

    The issue of insight in schizophrenia must be assumed to be one of the most important aspects of the clinical examination. Comprehensive studies have shown that between 50% and 80% of all patients suffering from schizophrenia do not believe that they have a disorder. In recent years, poor insight in schizophrenia has been the subject of increasing interest, as manifested in a number of studies discussed in the present review. Some of these studies focus on insight correlated to various parameters such as psychopathology, neuropsychology, clinical relevance and compliance. Other studies refer to more theoretical implications, among these the issue of defining the concept of insight: whether insight can be seen as a "primary" phenomenon in schizophrenia, and whether insight may be graduated, dimensioned or increased. Several authors have developed rating scales in an attempt to obtain a measure for the degree or dimension of insight. Here, the range of parameters employed gives an excellent impression of the complexity of the concept of insight. In the concluding discussion, a phenomenological aspect is brought in, in an attempt to place the concept of insight in relation to disturbances of the self in schizophrenia and to primary symptoms in schizophrenia, amongst these autism.

  18. Single atom spintronics

    International Nuclear Information System (INIS)

    Sullivan, M. R.; Armstrong, J. N.; Hua, S. Z.; Chopra, H. D.

    2005-01-01

    Full text: Single atom spintronics (SASS) represents the ultimate physical limit in device miniaturization. SASS is characterized by ballistic electron transport, and is a fertile ground for exploring new phenomena. In addition to the 'stationary' (field independent) scattering centers that have a small and fixed contribution to total transmission probability of electron waves, domain walls constitute an additional and enhanced source of scattering in these magnetic quantum point contacts (QPCs), the latter being both field and spin-dependent. Through the measurement of complete hysteresis loops as a function of quantized conductance, we present definitive evidence of enhanced backscattering of electron waves by atomically sharp domain walls in QPCs formed between microfabricated thin films [1]. Since domain walls move in a magnetic field, the magnitude of spin-dependent scattering changes as the QPC is cycled along its hysteresis loop. For example, as shown in the inset in Fig. 1, from zero towards saturation in a given field direction, the resistance varies as the wall is being swept away, whereas the resistance is constant upon returning from saturation towards zero, since in this segment of the hysteresis loop no domain wall is present across the contact. The observed spin-valve like behavior is realized by control over wall width and shape anisotropy. This behavior also unmistakably sets itself apart from any mechanical artifacts; additionally, measurements made on single atom contacts provide an artifact-free environment [2]. Intuitively, it is simpler to organize the observed BMR data according to all possible transitions between different conductance plateaus, as shown by the dotted line in Fig. 1; the solid circles show experimental data for Co, which follows the predicted scheme. Requisite elements for the observation of the effect will be discussed in detail along with a review of state of research in this field. Practically, the challenge lies in making

  19. Atoms: for war or peace

    Energy Technology Data Exchange (ETDEWEB)

    Subrahmanyam, K V

    1981-08-01

    History of nuclear power generation starting from the experimental split of uranium atom in 1938 to the establishment of the International Atomic Energy Agency is traced. In India, the Atomic Energy Commission was established with the major objective of developing nuclear power to make up India's deficiencies in energy sources. It is noted that from the very beginning the commission's activities were covered under a blanket of secrecy. According to the author, India's atomic energy programme stagnated after Dr. Bhabha's death. The Department of Atomic Energy diverted its attention to the nuclear explosion which was carried out in 1974. This event caused a great setback to the collaboration with Canada and USA in the nuclear power programme. The resulting problems are still not fully solved. The author maintains that the Department of Atomic Energy should have confined its efforts to the reactor development with special reference to the fast breeder reactor so that thorium can be utilised to the maximum advantage.

  20. Optical angular momentum and atoms.

    Science.gov (United States)

    Franke-Arnold, Sonja

    2017-02-28

    Any coherent interaction of light and atoms needs to conserve energy, linear momentum and angular momentum. What happens to an atom's angular momentum if it encounters light that carries orbital angular momentum (OAM)? This is a particularly intriguing question as the angular momentum of atoms is quantized, incorporating the intrinsic spin angular momentum of the individual electrons as well as the OAM associated with their spatial distribution. In addition, a mechanical angular momentum can arise from the rotation of the entire atom, which for very cold atoms is also quantized. Atoms therefore allow us to probe and access the quantum properties of light's OAM, aiding our fundamental understanding of light-matter interactions, and moreover, allowing us to construct OAM-based applications, including quantum memories, frequency converters for shaped light and OAM-based sensors.This article is part of the themed issue 'Optical orbital angular momentum'. © 2017 The Author(s).

  1. Self-lacing atom chains

    International Nuclear Information System (INIS)

    Zandvliet, Harold J W; Van Houselt, Arie; Poelsema, Bene

    2009-01-01

    The structural and electronic properties of self-lacing atomic chains on Pt modified Ge(001) surfaces have been studied using low-temperature scanning tunnelling microscopy and spectroscopy. The self-lacing chains have a cross section of only one atom, are perfectly straight, thousands of atoms long and virtually defect free. The atomic chains are composed of dimers that have their bonds aligned in a direction parallel to the chain direction. At low temperatures the atomic chains undergo a Peierls transition: the periodicity of the chains doubles from a 2 x to a 4 x periodicity and an energy gap opens up. Furthermore, at low temperatures (T<80 K) novel quasi-one-dimensional electronic states are found. These quasi-one-dimensional electronic states originate from an electronic state of the underlying terrace that is confined between the atomic chains.

  2. Spectroscopy of highly ionized atoms

    International Nuclear Information System (INIS)

    Livingston, A.E.

    1987-01-01

    The atomic structure and decay characteristics of excited states in multiply ionized atoms represent a fertile testing ground for atomic calculations ranging from accurate ab initio theory for few-electron systems to practical semi-empirical approaches for many-electron species. Excitation of fast ions by thin foils generally produces the highest ionization stages for heavy ions in laboratory sources. The associated characteristics of spectroscopic purity and high time resolution provide unique capabilities for studying the atomic properties of highly-ionized atoms. This report is limited to a brief discussion of three classes of atomic systems that are experiencing current theoretical and experimental interest: precision structure of helium-like ions, fine structure of doubly-excited states, and lifetimes of metastable states. Specific measurements in each of these types of systems are mentioned, with emphasis on the relation to studies involving slow, highly-charged ions

  3. Atoms in dense plasmas

    International Nuclear Information System (INIS)

    More, R.M.

    1987-01-01

    This paper covers some aspects of the theory of atomic processes in dense plasmas. Because the topic is very broad, a few general rules which give useful guidance about the typical behavior of dense plasmas have been selected. These rules are illustrated by semiclassical estimates, scaling laws and appeals to more elaborate calculations. Included in the paper are several previously unpublished results including a new mechanism for electron-ion heat exchange (section II), and an approximate expression for oscillator-strengths of highly charged ions (section V). However the main emphasis is not upon practical formulas but rather on questions of fundamental theory, the structural ingredients which must be used in building a model for plasma events. What are the density effects and how does one represent them? Which are most important? How does one identify an incorrect theory? The general rules help to answer these questions. 106 references, 23 figures, 2 tables

  4. The SILVA atomic process

    International Nuclear Information System (INIS)

    Cazalet, J.

    1997-01-01

    The SILVA laser isotope separation process is based on the laser selective photo-ionization of uranium atomic vapour; the process is presently under development by CEA and COGEMA in France, with the aim to reduce by a factor three the cost of uranium enrichment. The two main components of a SILVA process plant are the lasers (copper vapour lasers and dye lasers) and the separator for the vaporization (with a high energy electron beam), ionization and separation operations. Researches on the SILVA process started in 1985 and the technical and economical feasibility is to be demonstrated in 1997. The progresses of similar rival processes and other processes are discussed and the remaining research stages and themes of the SILVA program are presented

  5. The SILVA atomic process

    International Nuclear Information System (INIS)

    Cazalet, J.

    1996-01-01

    The SILVA isotopic laser separation process of atomic uranium vapor requires the use of specific high power visible light laser devices and systems for uranium evaporation and management (separation modules). The CEA, in collaboration with industrialists, has developed these components and built some demonstration plants. The scientific and technological challenges raised by this process are now surmounted. The principle of the SILVA process is the selective photo-ionization of uranium isotopes using laser photon beams tuned to the exact excitation frequency of the isotope electron layers. This paper describes the principle of the SILVA process (lasers and separator), the technical feasibility and actual progress of the program and its future steps, its economical stakes, and the results obtained so far. (J.S.). 2 figs., 2 photos

  6. Atomic absorption spectrophotometer

    International Nuclear Information System (INIS)

    Stockdale, T. J.

    1985-01-01

    In atomic absorption spectrophotometer, a reference path may be provided for radiation which excludes the flame. This radiation provides a signal from a detector which varies only with the instrumental drift produced by variations in the radiation source brightness and by variations in detector gain. The signal can be used to compensate for drift in other signals received through a sample path including the flame. In the present invention, radiation passes through the sample path continuously during measurement, and only through the reference path between sample measurements. Movable mirrors shift the radiation between the paths upon externally applied commands. Conveniently, the reference path measurement is made while the flame is stabilized during the change between samples. The reference path measurements are stored and used to correct for drift

  7. Atomic and gravitational clocks

    International Nuclear Information System (INIS)

    Canuto, V.M.; City Coll., New York; Goldman, I.

    1982-01-01

    Atomic and gravitational clocks are governed by the laws of electrodynamics and gravity respectively. While the strong equivalence principle (SEP) assumes that the two clocks have been synchronous at all times, recent planetary data seem to suggest a possible violation of the SEP. Past analysis of the implications of an SEP violation on different physical phenomena revealed no disagreement. However, these studies assumed that the two different clocks can be consistently constructed within the framework. The concept of scale invariance, and the physical meaning of different systems of units, are now reviewed and the construction of two clocks that do not remain synchronous-whose rates are related by a non-constant function βsub(a)-is demonstrated. The cosmological character of βsub(a) is also discussed. (author)

  8. Atomic war field Europe

    International Nuclear Information System (INIS)

    Calder, N.

    1980-01-01

    Progressive atomic weapons, results of a perfect and perfidious technology face each other in the centre of a possible crisis - in Europe. The strategists of the Warszhaw Pact and of Nato seem very optimistic, which they owe to their professions, the population's increasing fear of a war, however, can no longer be denied. Nervous military personnel, political and religions fanatics and perplexed politicians sit at the switches of fear - without a concept and without alternatives. Despite this alarming conditions, Nigel Calder who has investigated in the USA and in the USSR, and in Europe, managed to remain a calm spectator of the imminent apocalypse. Without compromises and clearly he analyses the nearly hopeless consequences resulting from the changed world-political situation, the tremendously fast development of the arms technology, and the crazy strategical doctrines in East and West and in the Third World. (orig./UA) [de

  9. Atoms against the universe

    International Nuclear Information System (INIS)

    Senovilla, J.; Raul Vera, M.M.

    1999-01-01

    In Woody Allen's masterpiece Annie Hall the main character is worried about the expansion of the universe. Indeed, during a childhood visit to his psychiatrist, his mother admonishes him: ''You're here in Brooklyn! Brooklyn is not expanding!''. But is that really true? Relativists have attacked this naive question many times and have arrived at different answers. New light has now been thrown on the subject by William Bonnor from Queen Mary and Westfield College in London by considering the influence of the expanding universe on the size of the hydrogen atom (Class. Quantum Grav. 1999 16 1313). According to Bonner's calculations we can conclude that the cosmic expansion does not affect human-scale objects like laboratories and our bodies. In this article the authors explain the reasoning behind this research and its thought provoking consequences. (UK)

  10. Atomic Weapons Establishment Bill

    International Nuclear Information System (INIS)

    Clark, Alan; Dalyell, Tam; Haynes, Frank

    1990-01-01

    The Bill debated concerns the government's proposal for the future organisations of the atomic weapons establishment in the United Kingdom. The proposals arise from a full review carried out in 1989 and include points raised by the Select Committee on the Trident programme. Studies of productivity, pay and conditions, information systems and long term manufacturing strategy have been started to enable recommendations of the reorganisation of the establishments to be made. The details of the Bill were debated for just over two hours. The debate is reported verbatim. The main issues were over the principle of contractorisation, possible staff redundancies, conditions of employment, safety and security. The proposal that the Bill be read a second time was carried. (UK)

  11. Atoms in astronomy

    Science.gov (United States)

    Blanchard, P. A.

    1976-01-01

    Aspects of electromagnetic radiation and atomic physics needed for an understanding of astronomical applications are explored. Although intended primarily for teachers, this brochure is written so that it can be distributed to students if desired. The first section, Basic Topics, is suitable for a ninth-grade general science class; the style is simple and repetitive, and no mathematics or physics background is required. The second section, Intermediate and Advanced Topics, requires a knowledge of the material in the first section and assumes a generally higher level of achievement and motivation on the part of the student. These latter topics might fit well into junior-level physics, chemistry, or earth-science courses. Also included are a glossary, a list of references and teaching aids, class exercises, and a question and answer section.

  12. Safeguarding the atom

    International Nuclear Information System (INIS)

    Fischer, D.; Szasz, P.

    1985-01-01

    Safeguards play a key role in verifying the effectiveness of restraints on the spread of nuclear weapons. This book is a study of the safeguards system of the International Atomic Energy Agency, an important element of the non-proliferation regime. It focuses on the politics of safeguards, especially the political problems of the IAEA and of the day-to-day application of safeguards. It contains a critical appraisal and proposals for ways of improving existing procedures and of adapting them to the political and technological changes of recent years. IAEA safeguards represent the world's first and so far only attempt to verify an arms control agreement by systematic on-site inspection, and their applicability to other arms control measures is examined. (author)

  13. Atomic iodine laser

    International Nuclear Information System (INIS)

    Fisk, G.A.; Gusinow, M.A.; Hays, A.K.; Padrick, T.D.; Palmer, R.E.; Rice, J.K.; Truby, F.K.; Riley, M.E.

    1978-05-01

    The atomic iodine photodissociation laser has been under intensive study for a number of years. The physics associated with this system is now well understood and it is possible to produce a 0.1 nsec (or longer) near-diffraction-limited laser pulse which can be amplified with negligible temporal distortion and little spatial deformation. The output of either a saturated or unsaturated amplifier consists of a high-fidelity near-diffraction-limited, energetic laser pulse. The report is divided into three chapters. Chapter 1 is a survey of the important areas affecting efficient laser operation and summarizes the findings of Chap. 2. Chapter 2 presents detailed discussions and evaluations pertinent to pumps, chemical regeneration, and other elements in the overall laser system. Chapter 3 briefly discusses those areas that require further work and the nature of the work required to complete the full-scale evaluation of the applicability of the iodine photodissociation laser to the inertial confinement program

  14. Atomic power plant

    International Nuclear Information System (INIS)

    Kawakami, Hiroto.

    1975-01-01

    Object: To permit decay heat to be reliably removed after reactor shut-down at such instance as occurrence of loss of power by means of an emergency water supply pump. Structure: An atomic power plant having a closed cycle constructed by connecting a vapor generator, a vapor valve, a turbine having a generator, a condenser, and a water supply pump in the mentioned order, and provided with an emergency water supply pump operated when there is a loss of power to the water supply pump, a degasifier pressure holding means for holding the pressure of the degasifier by introducing part of the vapor produced from said vapor generator, and a valve for discharge to atmosphere provided on the downstream side of said vapor generator. (Kamimura, M.)

  15. Atomic Basic Blocks

    Science.gov (United States)

    Scheler, Fabian; Mitzlaff, Martin; Schröder-Preikschat, Wolfgang

    Die Entscheidung, einen zeit- bzw. ereignisgesteuerten Ansatz für ein Echtzeitsystem zu verwenden, ist schwierig und sehr weitreichend. Weitreichend vor allem deshalb, weil diese beiden Ansätze mit äußerst unterschiedlichen Kontrollflussabstraktionen verknüpft sind, die eine spätere Migration zum anderen Paradigma sehr schwer oder gar unmöglich machen. Wir schlagen daher die Verwendung einer Zwischendarstellung vor, die unabhängig von der jeweils verwendeten Kontrollflussabstraktion ist. Für diesen Zweck verwenden wir auf Basisblöcken basierende Atomic Basic Blocks (ABB) und bauen darauf ein Werkzeug, den Real-Time Systems Compiler (RTSC) auf, der die Migration zwischen zeit- und ereignisgesteuerten Systemen unterstützt.

  16. Bettis Atomic Power Laboratory

    International Nuclear Information System (INIS)

    1992-01-01

    The Bettis Atomic Power Laboratory (Bettis) is owned by the US Department of Energy (DOE) and has been operated under Government contract by the Westinghouse Electric Corporation since 1949. The Bettis Site in West Mifflin, Pennsylvania conducts research and development work on improved nuclear propulsion plants for US Navy warships and is the headquarters for all of the Laboratory's operations. For many years, environmental monitoring has been performed to demonstrate that the Bettis Site is being operated in accordance with environmental standards. While the annual report describes monitoring practices and results, it does not describe the nature and environmental aspects of work and facilities at the Bettis Site nor give a historical perspective of Bettis' operations. The purpose of this report is to provide this information as well as background information, such as the geologic and hydrologic nature of the Bettis Site, pertinent to understanding the environmental aspects of Bettis operations. Waste management practices are also described

  17. Atomic absorption spectrophotometry in perspective

    International Nuclear Information System (INIS)

    Soffiantini, V.

    1981-01-01

    Atomic absorption spectrophotometry is essentially an analytical technique used for quantitative trace metal analysis in a variety of materials. The speed and specificity of the technique is its greatest advantage over other analytical techniques. What atomic absorption spectrophotometry can and cannot do and its advantages and disadvantages are discussed, a summary of operating instructions are given, as well as a summary of analytical interferences. The applications of atomic absorption spectrophotometry are also shortly discussed

  18. Molecular invariants: atomic group valence

    International Nuclear Information System (INIS)

    Mundim, K.C.; Giambiagi, M.; Giambiagi, M.S. de.

    1988-01-01

    Molecular invariants may be deduced in a very compact way through Grassman algebra. In this work, a generalized valence is defined for an atomic group; it reduces to the Known expressions for the case of an atom in a molecule. It is the same of the correlations between the fluctions of the atomic charges qc and qd (C belongs to the group and D does not) around their average values. Numerical results agree with chemical expectation. (author) [pt

  19. Atomic Australia: 1944-1990

    International Nuclear Information System (INIS)

    Cawte, Alice.

    1992-01-01

    This book tells how successive Australian governments pursued the elusive uranium dream. With Australian uranium committed to the West's atomic arsenals, Australia seemed set to become a nation powered by the atom. But by the mid-1950 the Australian government learnt that their expectations were premature, if not unrealistic. The background of the creation of the Australian Atomic Energy Commission is also given along with the examination of the uranium controversies of the 1970s and 1980s. 150 refs

  20. Energy levels of muonic atoms

    International Nuclear Information System (INIS)

    Borie, E.; Rinker, G.A.

    1982-01-01

    The theory of muonic atoms is a complex and highly developed combination of nuclear physics, atomic physics, and quantum electrodynamics. Perhaps nowhere else in microscopic physics are such diverse branches so intimately intertwined and yet readily available for precise experimental verification or rejection. In the present review we summarize and discuss all of the most important components of muonic atom theory, and show in selected cases how this theory meets experimental measurements

  1. Stanford polarized atomic beam target

    International Nuclear Information System (INIS)

    Mavis, D.G.; Dunham, J.S.; Hugg, J.W.; Glavish, H.F.

    1976-01-01

    A polarized atomic beam source was used to produce an atomic hydrogen beam which was in turn used as a polarized proton target. A target density of 2 x 10'' atoms/cm 3 and a target polarization of 0.37 without the use of rf transitions were measured. These measurements indicate that a number of experiments are currently feasible with a variety of polarized target beams

  2. Study on laser atomic spectroscopy

    International Nuclear Information System (INIS)

    Lee, Jong Min; Song, Kyu Seok; Jeong, Do Young; Kim, Chul Joong; Han, Phil Soon

    1992-01-01

    Electric discharge type atomic vaporizer is developed for the spectroscopic study on actinide elements. Laser induced fluorescence study on actinide elements is performed by using this high temperature type atomizer. For the effective photoionization of elements, copper vapor laser pumped dye laser and electron beam heating type atomic vaporizer are built and their characteristics are measured. In addition, resonance ionization mass spectroscopic analysis for lead sample as well as laser induced fluorescence study on uranium sample in solution phase is made. (Author)

  3. Atomic beams probe surface vibrations

    International Nuclear Information System (INIS)

    Robinson, A.L.

    1982-01-01

    In the last two years, surface scientist have begun trying to obtain the vibrational frequencies of surface atoms in both insulating and metallic crystals from beams of helium atoms. It is the inelastic scattering that researchers use to probe surface vibrations. Inelastic atomic beam scattering has only been used to obtain vibrational frequency spectra from clean surfaces. Several experiments using helium beams are cited. (SC)

  4. Insights into PRA methodologies

    International Nuclear Information System (INIS)

    Gallagher, D.; Lofgren, E.; Atefi, B.; Liner, R.; Blond, R.; Amico, P.

    1984-08-01

    Probabilistic Risk Assessments (PRAs) for six nuclear power plants were examined to gain insight into how the choice of analytical methods can affect the results of PRAs. The PRA sreflectope considered was limited to internally initiated accidents sequences through core melt. For twenty methodological topic areas, a baseline or minimal methodology was specified. The choice of methods for each topic in the six PRAs was characterized in terms of the incremental level of effort above the baseline. A higher level of effort generally reflects a higher level of detail or a higher degree of sophistication in the analytical approach to a particular topic area. The impact on results was measured in terms of how additional effort beyond the baseline level changed the relative importance and ordering of dominant accident sequences compared to what would have been observed had methods corresponding to the baseline level of effort been employed. This measure of impact is a more useful indicator of how methods affect perceptions of plant vulnerabilities than changes in core melt frequency would be. However, the change in core melt frequency was used as a secondary measure of impact for nine topics where availability of information permitted. Results are presented primarily in the form of effort-impact matrices for each of the twenty topic areas. A suggested effort-impact profile for future PRAs is presented

  5. Grigor Narekatsi's astronomical insights

    Science.gov (United States)

    Poghosyan, Samvel

    2015-07-01

    What stand out in the solid system of Gr. Narekatsi's naturalistic views are his astronomical insights on the material nature of light, its high speed and the Sun being composed of "material air". Especially surprising and fascinating are his views on stars and their clusters. What astronomers, including great Armenian academician V. Ambartsumian (scattering of stellar associations), would understand and prove with much difficulty thousand years later, Narekatsi predicted in the 10th century: "Stars appear and disappear untimely", "You who gather and scatter the speechless constellations, like a flock of sheep". Gr. Narekatsti's reformative views were manifested in all the spheres of the 10th century social life; he is a reformer of church life, great language constructor, innovator in literature and music, freethinker in philosophy and science. His ideology is the reflection of the 10th century Armenian Renaissance. During the 9th-10th centuries, great masses of Armenians, forced to migrate to the Balkans, took with them and spread reformative ideas. The forefather of the western science, which originated in the period of Reformation, is considered to be the great philosopher Nicholas of Cusa. The study of Gr. Narekatsti's logic and naturalistic views enables us to claim that Gr. Narekatsti is the great grandfather of European science.

  6. O insight em psiquiatria

    Directory of Open Access Journals (Sweden)

    Ana Margarida P. Cardoso

    2008-12-01

    Full Text Available O sinal de que algo está a acontecer contribui para que o paciente reconheça que alguma coisa de estranho se está a passar consigo. Este reconhecimento faz com que o sujeito possa desempenhar uma função activa e seja um elemento colaborante do seu processo de recuperação. Cada doença apresenta, contudo, diferentes sintomas, uma vez que cada doença psiquiátrica consiste em diferentes perturbações com diversos efeitos sobre o funcionamento mental. Desta maneira, o fenómeno do insight que é registado em cada doença é diferente e expressa-se sob diferentes formas, não somente devido às manifestações clínicas da doença mas também devido às características individuais do sujeito.

  7. Giant atoms cast long shadow

    International Nuclear Information System (INIS)

    Amato, I.

    1996-01-01

    Atoms swollen with energy can serve as supersensitive detectors. They also probe the shadow realm where the quantum world of the atom gives way to the familiar classical world. Created in the laboratory, where they live for a few milliseconds inside vacuum chambers, Rydberg atoms acquire their girth when one or sometimes two of their electrons are excited to very high energy levels, displacing them far from the nuclear core. This article describes the atoms, the history of their identification, and future possibilities. 2 figs

  8. Precision measurement with atom interferometry

    International Nuclear Information System (INIS)

    Wang Jin

    2015-01-01

    Development of atom interferometry and its application in precision measurement are reviewed in this paper. The principle, features and the implementation of atom interferometers are introduced, the recent progress of precision measurement with atom interferometry, including determination of gravitational constant and fine structure constant, measurement of gravity, gravity gradient and rotation, test of weak equivalence principle, proposal of gravitational wave detection, and measurement of quadratic Zeeman shift are reviewed in detail. Determination of gravitational redshift, new definition of kilogram, and measurement of weak force with atom interferometry are also briefly introduced. (topical review)

  9. Quantum information with Rydberg atoms

    DEFF Research Database (Denmark)

    Saffman, Mark; Walker, T.G.; Mølmer, Klaus

    2010-01-01

    Rydberg atoms with principal quantum number n»1 have exaggerated atomic properties including dipole-dipole interactions that scale as n4 and radiative lifetimes that scale as n3. It was proposed a decade ago to take advantage of these properties to implement quantum gates between neutral atom...... of multiqubit registers, implementation of robust light-atom quantum interfaces, and the potential for simulating quantum many-body physics. The advances of the last decade are reviewed, covering both theoretical and experimental aspects of Rydberg-mediated quantum information processing....

  10. Chemical generation of iodine atoms

    Energy Technology Data Exchange (ETDEWEB)

    Hewett, Kevin B. [Directed Energy Directorate, Air Force Research Laboratory, 3550 Aberdeen Avenue SE, Kirtland AFB, NM 87117-5776 (United States)]. E-mail: kevin.hewett@kirtland.af.mil; Hager, Gordon D. [Directed Energy Directorate, Air Force Research Laboratory, 3550 Aberdeen Avenue SE, Kirtland AFB, NM 87117-5776 (United States); Crowell, Peter G. [Northrup Grumman Information Technology, Science and Technology Operating Unit, Advanced Technology Division, P.O. Box 9377, Albuquerque, NM 87119-9377 (United States)

    2005-01-10

    The chemical generation of atomic iodine using a chemical combustor to generate the atomic fluorine intermediate, from the reaction of F{sub 2} + H{sub 2}, followed by the production of atomic iodine, from the reaction of F + HI, was investigated. The maximum conversion efficiency of HI into atomic iodine was observed to be approximately 75%, which is in good agreement with the theoretical model. The conversion efficiency is limited by the formation of iodine monofluoride at the walls of the combustor where the gas phase temperature is insufficient to dissociate the IF.

  11. Predicting synergy in atomic layer etching

    Energy Technology Data Exchange (ETDEWEB)

    Kanarik, Keren J. [Lam Research Corp., Fremont, CA (United States); Tan, Samantha [Lam Research Corp., Fremont, CA (United States); Yang, Wenbing [Lam Research Corp., Fremont, CA (United States); Kim, Taeseung [Lam Research Corp., Fremont, CA (United States); Lill, Thorsten [Lam Research Corp., Fremont, CA (United States); Kabansky, Alexander [Lam Research Corp., Fremont, CA (United States); Hudson, Eric A. [Lam Research Corp., Fremont, CA (United States); Ohba, Tomihito [Lam Research Corp., Fremont, CA (United States); Nojiri, Kazuo [Lam Research Corp., Fremont, CA (United States); Yu, Jengyi [Lam Research Corp., Fremont, CA (United States); Wise, Rich [Lam Research Corp., Fremont, CA (United States); Berry, Ivan L. [Lam Research Corp., Fremont, CA (United States); Pan, Yang [Lam Research Corp., Fremont, CA (United States); Marks, Jeffrey [Lam Research Corp., Fremont, CA (United States); Gottscho, Richard A. [Lam Research Corp., Fremont, CA (United States)

    2017-03-27

    Atomic layer etching (ALE) is a multistep process used today in manufacturing for removing ultrathin layers of material. In this article, the authors report on ALE of Si, Ge, C, W, GaN, and SiO2 using a directional (anisotropic) plasma-enhanced approach. The authors analyze these systems by defining an “ALE synergy” parameter which quantifies the degree to which a process approaches the ideal ALE regime. This parameter is inspired by the ion-neutral synergy concept introduced in the 1979 paper by Coburn and Winters. ALE synergy is related to the energetics of underlying surface interactions and is understood in terms of energy criteria for the energy barriers involved in the reactions. Synergistic behavior is observed for all of the systems studied, with each exhibiting behavior unique to the reactant–material combination. By systematically studying atomic layer etching of a group of materials, the authors show that ALE synergy scales with the surface binding energy of the bulk material. This insight explains why some materials are more or less amenable to the directional ALE approach. Furthermore, they conclude that ALE is both simpler to understand than conventional plasma etch processing and is applicable to metals, semiconductors, and dielectrics.

  12. Cognitive insight: A systematic review.

    Science.gov (United States)

    Van Camp, L S C; Sabbe, B G C; Oldenburg, J F E

    2017-07-01

    Cognitive insight is the ability to re-evaluate thoughts and beliefs in order to make thoughtful conclusions. It differs from clinical insight, as it focuses on more general metacognitive processes. Therefore, it could be relevant to diverse disorders and non-clinical subjects. There is a growing body of research on cognitive insight in individuals with and without psychosis. This review has summarised the current state of the art regarding this topic. We conclude that while cognitive insight in its current form seems valid for use in individuals with psychosis, it is less so for individuals without psychosis. Additionally, higher cognitive insight not always leads to better psychological functioning. For instance, higher levels of self-reflection are often associated with depressive mood. We therefore recommend the sub-components of cognitive insight to be studied separately. Also, it is unclear what position cognitive insight takes within the spectrum of metacognitive processes and how it relates to other self-related concepts that have been defined previously in literature. Combining future and past research on cognitive insight and its analogue concepts will help in the formation of a uniform definition that fits all subjects discussed here. Copyright © 2017. Published by Elsevier Ltd.

  13. Hyperons: Insights into baryon structures

    International Nuclear Information System (INIS)

    Lach, J.

    1991-08-01

    The baryon octet is composed mainly of hyperons. Modern high energy hyperon beams provide a tool for the study of hyperon static properties and interactions. Experiments with these beams have provided new insights into hyperon rare decays, magnetic moments, and interactions. These experiments provide us with insights into the strong, weak, and electromagnetic structure of the baryons. 65 refs., 45 figs., 5 tabs

  14. Surface features on Sahara soil dust particles made visible by atomic force microscope (AFM) phase images

    OpenAIRE

    G. Helas; M. O. Andreae

    2008-01-01

    We show that atomic force microscopy (AFM) phase images can reveal surface features of soil dust particles, which are not evident using other microscopic methods. The non-contact AFM method is able to resolve topographical structures in the nanometer range as well as to uncover repulsive atomic forces and attractive van der Waals' forces, and thus gives insight to surface properties. Though the method does not allow quantitative assignment in terms of chemical compound description, it clearly...

  15. Atomic Force Microscopy and Real Atomic Resolution. Simple Computer Simulations

    NARCIS (Netherlands)

    Koutsos, V.; Manias, E.; Brinke, G. ten; Hadziioannou, G.

    1994-01-01

    Using a simple computer simulation for AFM imaging in the contact mode, pictures with true and false atomic resolution are demonstrated. The surface probed consists of two f.c.c. (111) planes and an atomic vacancy is introduced in the upper layer. Changing the size of the effective tip and its

  16. Atomic masses 1995. The 1995 atomic mass evaluation

    International Nuclear Information System (INIS)

    Audi, G.; Wapstra, A.H.

    1995-01-01

    The 1995 atomic mass evaluation by G. Audi and A.H. Wapstra is documented. The resulting data files containing recommended values of atomic masses, obtained by experiment or systematics, and related data such as reaction and separation energies are described. The data files can be obtained through online services from several nuclear data centers or on magnetic tape, free of charge. (author)

  17. Atomic masses 1993. The 1993 atomic mass evaluation

    International Nuclear Information System (INIS)

    Audi, G.; Wapstra, A.H.

    1993-01-01

    The 1993 atomic mass evaluation by G. Audi and A.H. Wapstra is documented. The resulting data files containing recommended values of atomic masses, obtained by experiment of systematics, and related data such as reaction and separation energies are described. The data files can be obtained through online services from several nuclear data centers or on magnetic tape, free of charge. (author)

  18. Systematics of atom-atom collision strengths at high speeds

    International Nuclear Information System (INIS)

    Gillespie, G.H.; Inokuti, M.

    1980-01-01

    The collision strengths for atom-atom collisions at high speeds are calculated in the first Born approximation. We studied four classes of collisions, distinguished depending upon whether each of the collision partners becomes excited or not. The results of numerical calculations of the collision strengths are presented for all neutral atoms with Z< or =18. The calculations are based on atomic form factors and incoherent scattering functions found in the literature. The relative contribution of each class of collision processes to the total collision cross section is examined in detail. In general, inelastic processes dominate for low-Z atoms, while elastic scattering is more important for large Z. Other systematics of the collision strengths are comprehensively discussed. The relevant experimental literature has been surveyed and the results of this work for the three collision systems H-He, He-He, and H-Ar are compared with the data for electron-loss processes. Finally, suggestions are made for future work in measurements of atom-atom and ion-atom collision cross sections

  19. prepared via atom transfer radical polymerization, reverse atom

    Indian Academy of Sciences (India)

    Synthesis and characterization of poly(2-ethylhexyl acrylate) prepared via atom transfer radical polymerization, reverse atom transfer radical polymerization and ... Zydex Industries, 25-A Gandhi Oil Mill Compound, Gorwa, Vadodara 390 016, India; Rubber Technology Centre, Indian Institute of Technology Kharagpur, ...

  20. Atomic-resolution studies of In{sub 2}O{sub 3}-ZnO compounds on aberration-corrected electron microscopes

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Wentao

    2009-10-23

    In this work, the characteristic inversion domain microstructures of In{sub 2}O{sub 3}(ZnO){sub m} (m=30) compounds were investigated by TEM methods. At bright-atom contrast condition, atomically resolved HR-TEM images of In{sub 2}O{sub 3}(ZnO){sub 30} were successfully acquired in [1 anti 100] zone axis of ZnO, with projected metal columns of {proportional_to}1.6 A well resolved. From contrast maxima in the TEM images, local lattice distortions at the pyramidal inversion domain boundaries were observed for the first time. Lattice displacements and the strain field in two-dimensions were visualized and measured using the 'DALI' algorithm. Atomically resolved single shot and focal series images of In{sub 2}O{sub 3}(ZnO){sub 30} were achieved in both zone axes of ZnO, [1 anti 100] and [2 anti 1 anti 10], respectively. The electron waves at the exit-plane were successfully reconstructed using the software package 'TrueImage'. Finally, a three dimensional atomic structure model for the pyramidal IDB was proposed, with an In distribution of 10%, 20%, 40%, 20% and 10% of In contents over 5 atom columns along basal planes, respectively. Through a detailed structural study of In{sub 2}O{sub 3}(ZnO){sub m} compounds by using phase-contrast and Z-contrast imaging at atomic resolution, In{sup 3+} atoms are determined with trigonal bi-pyramidal co-ordination and are distributed at the pyramidal IDBs. (orig.)

  1. High efficiency atomic hydrogen source

    International Nuclear Information System (INIS)

    Lagomarsino, V.; Bassi, D.; Bertok, E.; De Paz, M.; Tommasini, F.

    1974-01-01

    This work presents preliminary results of research intended to produce a M.W. discharge atomic hydrogen source with good dissociation at pressures larger than 10 torr. Analysis of the recombination process at these pressures shows that the volume recombination by three body collisions may be more important than wall recombination or loss of atoms by diffusion and flow outside the discharge region

  2. Bohmian picture of Rydberg atoms

    Indian Academy of Sciences (India)

    Abstract. Unlike the previous theoretical results based on standard quantum mechanics that established the nearly elliptical shapes for the centre-of-mass motion in Rydberg atoms using numerical simulations, we show analytically that the Bohmian trajectories in Rydberg atoms are nearly elliptical.

  3. Laser cooling of neutral atoms

    International Nuclear Information System (INIS)

    1993-01-01

    A qualitative description of laser cooling of neutral atoms is given. Two of the most important mechanisms utilized in laser cooling, the so-called Doppler Cooling and Sisyphus Cooling, are reviewed. The minimum temperature reached by the atoms is derived using simple arguments. (Author) 7 refs

  4. The atomic energy basic law

    International Nuclear Information System (INIS)

    1977-01-01

    The law establishes clearly the principles that Japan makes R and D, and utilizations of atomic energy only for the peaceful purposes. All the other laws and regulations concerning atomic energy are based on the law. The first chapter lays down the above mentioned objective of the law, and gives definitions of basic concepts and terms, such as atomic energy, nuclear fuel material, nuclear source material, nuclear reactor and radiation. The second chapter provides for the establishment of Atomic Energy Commission which conducts plannings and investigations, and also makes decisions concerning R and D, and utilizations of atomic energy. The third chapter stipulates for establishment of two government organizations which perform R and D of atomic energy developments including experiments and demonstrations of new types of reactors, namely, Atomic Energy Research Institute and Power Reactor and Nuclear Fuel Development Corporation. Chapters from 4th through 8th provide for the regulations on development and acquisition of the minerals containing nuclear source materials, controls on nuclear fuel materials and nuclear reactors, administrations of the patents and inventions concerning atomic energy, and also prevention of injuries due to radiations. The last 9th chapter requires the government and its appointee to compensate the interested third party for damages in relation to the exploitation of nuclear source materials. (Matsushima, A.)

  5. Atomic absorption instrument functional description

    International Nuclear Information System (INIS)

    Bystroff, R.I.; Boyle, W.G. Jr.; Barton, G.W. Jr.

    1976-01-01

    This report describes a proposed system for automating atomic absorption analysis. The system consists of two atomic absorption instruments and an automatic sampler that can be attached to either instrument. A computer program controls the sampling and gathers data. The program then uses the data to perform bookkeeping, data processing, and report writing

  6. Electromagnetic trapping of neutral atoms

    International Nuclear Information System (INIS)

    Metcalf, H.J.

    1986-01-01

    Cooling and trapping of neutral atoms is a new branch of applied physics that has potential for application in many areas. The authors present an introduction to laser cooling and magnetic trapping. Some basic ideas and fundamental limitations are discussed, and the first successful experiments are reviewed. Trapping a neutral object depends on the interaction between an inhomogeneous electromagnetic field and a multiple moment that results in the exchange of kinetic for potential energy. In neutral atom traps, the potential energy must be stored as internal atomic energy, resulting in two immediate and extremely important consequences. First, the atomic energy levels will necessarily shift as the atoms move in the trap, and, second, practical traps for ground state neutral atoms atr necessarily very shallow compared to thermal energy. This small depth also dictates stringent vacuum requirements because a trapped atom cannot survive a single collision with a thermal energy background gas molecule. Neutral trapping, therefore, depends on substantial cooling of a thermal atomic sample and is inextricably connected with the cooling process

  7. Stopping atoms with diode lasers

    International Nuclear Information System (INIS)

    Watts, R.N.; Wieman, C.E.

    1986-01-01

    The use of light pressure to cool and stop neutral atoms has been an area of considerable interest recently. Cooled neutral atoms are needed for a variety of interesting experiments involving neutral atom traps and ultrahigh-resolution spectroscopy. Laser cooling of sodium has previously been demonstrated using elegant but quite elaborate apparatus. These techniques employed stabilized dye lasers and a variety of additional sophisticated hardware. The authors have demonstrated that a frequency chirp technique can be implemented using inexpensive diode lasers and simple electronics. In this technique the atoms in an atomic beam scatter resonant photons from a counterpropagating laser beam. The momentum transfer from the photons slows the atoms. The primary difficulty is that as the atoms slow their Doppler shift changes, and so they are no longer in resonance with the incident photons. In the frequency chirp technique this is solved by rapidly changing the laser frequency so that the atoms remain in resonance. To achieve the necessary frequency sweep with a dye laser one must use an extremely sophisticated high-speed electrooptic modulator. With a diode laser, however, the frequency can be smoothly and rapidly varied over many gigahertz simply by changing the injection current

  8. Atomic Energy Authority Act 1954

    International Nuclear Information System (INIS)

    1954-01-01

    This Act provides for the setting up of an Atomic Energy Authority for the United Kingdom. It also makes provision for the Authority's composition, powers, duties, rights and liabilities, and may amend, as a consequence of the establishment of the Authority and in connection therewith, the Atomic Energy Act, 1946, the Radioactive Substances Act 1948 and other relevant enactments. (NEA) [fr

  9. Hot atom chemistry of carbon

    International Nuclear Information System (INIS)

    Wolf, A.P.

    1975-01-01

    The chemistry of energetic carbon atoms is discussed. The experimental approach to studies that have been carried out is described and the mechanistic framework of hot carbon atom reactions is considered in some detail. Finally, the direction that future work might take is examined, including the relationship of experimental to theoretical work. (author)

  10. Atoms in astrophysics

    CERN Document Server

    Eissner, W; Hummer, D; Percival, I

    1983-01-01

    It is hard to appreciate but nevertheless true that Michael John Seaton, known internationally for the enthusiasm and skill with which he pursues his research in atomic physics and astrophysics, will be sixty years old on the 16th of January 1983. To mark this occasion some of his colleagues and former students have prepared this volume. It contains articles that de­ scribe some of the topics that have attracted his attention since he first started his research work at University College London so many years ago. Seaton's association with University College London has now stretched over a period of some 37 years, first as an undergraduate student, then as a research student, and then, successively, as Assistant Lecturer, Lecturer, Reader, and Professor. Seaton arrived at University College London in 1946 to become an undergraduate in the Physics Department, having just left the Royal Air Force in which he had served as a navigator in the Pathfinder Force of Bomber Command. There are a number of stories of ho...

  11. ILO and atomic energy

    International Nuclear Information System (INIS)

    1961-01-01

    The work of the International Labour Organisation in the field of atomic energy has been concerned primarily with the protection of the worker against radiation; in this respect it developed the work carried out before the war on the occupational pathology of roentgen ray operators, radium and radioactive substances and uranium. In view of the extremely serious consequences to society and the individual that would result from a neglect of the essential precautions, the ILO has to adopt international standards setting out the essential precautions that should be observed in a work which may entail a radiation hazard. The 44th International Labour Conference, meeting in the summer of 1960, adopted a convention and recommendation on this subject. The Convention applies to all activities involving exposure of workers to ionizing radiations in the course of their work and provides that each Member of the ILO which ratifies it shall undertake to give effect to it by means of laws or regulations, codes of practice or other appropriate means. It further provides that the necessary steps taken at the national level to ensure effective protection should be progressively brought in line with the provisions of the Convention after its ratification

  12. Beyond the atom

    International Nuclear Information System (INIS)

    Laurikainen, K.V.

    1988-01-01

    The Austrian physicist Wolfgang Pauli (1900-1958) is often called 'the conscience of physics'. He was famous for his sharp and critical mind which made him a central figure among the founders of quantum physics. To a lesser extent it is known that he also was an outstanding philosopher, especially interested in finding a new conception of reality and of causality. A careful study of the original sources of the past culminated in his study of Kepler and of medieval symbolism, a concept that played a central role in his discussion with C.G. Jung on the 'psychophysical problem'. Pauli considered in particular the sharp distinctions between knowledge and faith and between spirit and matter as dangerous. Rather they should complement each other in our comprehension of reality. The author tries for the first time to describe in detail Pauli's ideas. His book is based on the large and as yet unpublished correspondence between Pauli and M. Fierz. Its careful analysis adds depth and clarity to the few publications by Pauli on the above mentioned problems and explains why Pauli grasped the meaning of atomic theory more deeply than even N. Bohr himself. The book should be of interest both to philosophers and to physicists and should encourage further studies on the humanist W. Pauli and his contribution to our understanding of reality. But also the laymen pondering over the conception of reality in science will take advantage of this text. (orig.)

  13. Safeguards for the atom

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1959-10-15

    Concern over the destructive potentialities of nuclear energy has grown all over the world. In fact, it was this concern, coupled with an awareness of the equally great potentialities for peaceful prosperity, that led to the establishment of the International Atomic Energy Agency. That nuclear energy should be used solely for peaceful purposes is an ideal to which all people would subscribe. Realization of this ideal, however, is dependent on many complex factors which are outside the scope of the Agency. In its own limited sphere, however, the Agency has the responsibility to ensure that in its efforts to promote the peaceful uses it does not in any way increase the potentiality of military use. The possibility of military application is not the only danger that the Agency must guard against, it has a further function arising from the nature of the materials needed in atomic energy work. Since the basic materials are radioactive and since all ionizing radiation is potentially dangerous, the Agency must ensure that in helping its Member States to develop the peaceful uses of atomic energy it does not increase the hazards of nuclear radiation or radioactive contamination. It must establish standards of safe practice for activities carried out under its auspices or with its assistance. Since the safeguards will have two distinct objectives, a distinction can be made between those which will be designed to prevent the diversion of Agency assistance to military use and those against health and safety hazards. So far as the health and safety measures are concerned, a good deal of work has already been done in determining the standards of safe practice which will be the basis for the relevant rules. The Agency has published the first in its series of safety manuals, 'Safe Handling of Radioisotopes', which deals with such standards. Safeguards against the diversion or loss of nuclear materials and facilities are more difficult to devise. It is not considered feasible for

  14. Safeguards for the atom

    International Nuclear Information System (INIS)

    1959-01-01

    Concern over the destructive potentialities of nuclear energy has grown all over the world. In fact, it was this concern, coupled with an awareness of the equally great potentialities for peaceful prosperity, that led to the establishment of the International Atomic Energy Agency. That nuclear energy should be used solely for peaceful purposes is an ideal to which all people would subscribe. Realization of this ideal, however, is dependent on many complex factors which are outside the scope of the Agency. In its own limited sphere, however, the Agency has the responsibility to ensure that in its efforts to promote the peaceful uses it does not in any way increase the potentiality of military use. The possibility of military application is not the only danger that the Agency must guard against, it has a further function arising from the nature of the materials needed in atomic energy work. Since the basic materials are radioactive and since all ionizing radiation is potentially dangerous, the Agency must ensure that in helping its Member States to develop the peaceful uses of atomic energy it does not increase the hazards of nuclear radiation or radioactive contamination. It must establish standards of safe practice for activities carried out under its auspices or with its assistance. Since the safeguards will have two distinct objectives, a distinction can be made between those which will be designed to prevent the diversion of Agency assistance to military use and those against health and safety hazards. So far as the health and safety measures are concerned, a good deal of work has already been done in determining the standards of safe practice which will be the basis for the relevant rules. The Agency has published the first in its series of safety manuals, 'Safe Handling of Radioisotopes', which deals with such standards. Safeguards against the diversion or loss of nuclear materials and facilities are more difficult to devise. It is not considered feasible for

  15. Tau electron atoms at RHIC

    International Nuclear Information System (INIS)

    Weiss, M.S.

    1985-01-01

    An amusement ancillary to the proposed quark-gluon plasma production hypothesized from a relativistic heavy ion collider (RHIC is a sufficient quantity of tau electrons to potentially admit the study of its exotic atoms. In this paper the given wealth of nuclear phenomena is derived from muonic atoms assume a tau atom is more forthcoming of information due to the lower orbits entirely contained within the nucleus. It is the purpose of this brief note to discuss the production mechanism at a RHIC and to delineate some of the more obvious properties of the tau atom. As in the case of the mu, more exotic phenomena derived from resonance ''accidents'' with nuclear transitions takes place, but it would be presumptions to discuss them at this time. Given the complete containment in nuclear matter of the tau lepton in its innermost atomic orbits. An experiment performed with such an exotic species results in the measurement of its lifetime

  16. Atomic spectroscopy and radiative processes

    CERN Document Server

    Landi Degl'Innocenti, Egidio

    2014-01-01

    This book describes the basic physical principles of atomic spectroscopy and the absorption and emission of radiation in astrophysical and laboratory plasmas. It summarizes the basics of electromagnetism and thermodynamics and then describes in detail the theory of atomic spectra for complex atoms, with emphasis on astrophysical applications. Both equilibrium and non-equilibrium phenomena in plasmas are considered. The interaction between radiation and matter is described, together with various types of radiation (e.g., cyclotron, synchrotron, bremsstrahlung, Compton). The basic theory of polarization is explained, as is the theory of radiative transfer for astrophysical applications. Atomic Spectroscopy and Radiative Processes bridges the gap between basic books on atomic spectroscopy and the very specialized publications for the advanced researcher: it will provide under- and postgraduates with a clear in-depth description of theoretical aspects, supported by practical examples of applications.

  17. Multielectron effects in atomic processes

    International Nuclear Information System (INIS)

    Amusia, M.Ya.; Chernysheva, L.V.

    1999-01-01

    One demonstrates a prominent role of electron collectivization in atoms and quasi-atomic formations. Paper discusses in detail the approximation of random phases with exchange enabling to take account of these effects. One points out the necessity to go outside the terms of the approximation when studying some processes via combination of the approximation with the theory of disturbances. The results of the recently conducted estimations of cross sections of photoionization of atomic iodine and of its positive and negative ions, Xe + single-electron photoionization, resonance-amplified emission of photons in electron collisions with atoms and quasi-atomic formations, non-dipole corrections to the angular distribution of photoelectrons, probabilities of two electron transitions where the whole amount of energy releases in the form of one photon, illustrate the role of the collective effects [ru

  18. Optical angular momentum and atoms

    Science.gov (United States)

    2017-01-01

    Any coherent interaction of light and atoms needs to conserve energy, linear momentum and angular momentum. What happens to an atom’s angular momentum if it encounters light that carries orbital angular momentum (OAM)? This is a particularly intriguing question as the angular momentum of atoms is quantized, incorporating the intrinsic spin angular momentum of the individual electrons as well as the OAM associated with their spatial distribution. In addition, a mechanical angular momentum can arise from the rotation of the entire atom, which for very cold atoms is also quantized. Atoms therefore allow us to probe and access the quantum properties of light’s OAM, aiding our fundamental understanding of light–matter interactions, and moreover, allowing us to construct OAM-based applications, including quantum memories, frequency converters for shaped light and OAM-based sensors. This article is part of the themed issue ‘Optical orbital angular momentum’. PMID:28069766

  19. Electromagnetic transitions in the atom

    International Nuclear Information System (INIS)

    Ulehla, I.; Suk, M.; Trka, Z.

    1990-01-01

    Methods to achieve excitation of atoms are outlined and conditions necessary for the occurrence of electromagnetic transitions in the atomic shell are given. Radiative transitions between the energy states of the atom include stimulated absorption, spontaneous emission, and stimulated emission. Selection rules applying to the majority of observed transitions are given. The parity concept is explained. It is shown how the electromagnetic field and its interaction with the magnetic moment of the atom lead to a disturbance of the energy states of the atom and the occurrence of various electro-optical and magneto-optical phenomena. The Stark effect and electron spin resonance are described. X-rays and X-ray spectra, the Auger effect and the internal photoeffect are also dealt with. The principle of the laser is explained. (M.D.). 22 figs., 1 tab

  20. Exotic objects of atomic physics

    Science.gov (United States)

    Eletskii, A. V.

    2017-11-01

    There has been presented a short survey of physical properties, methods of production and exploration as well as directions of practical usage of the objects of atomic physics which are not yet described in detail in modern textbooks and manuals intended for students of technical universities. The family of these objects includes negative and multicharged ions, Rydberg atoms, excimer molecules, clusters. Besides of that, in recent decades this family was supplemented with new nanocarbon structures such as fullerenes, carbon nanotubes and graphene. The textbook “Exotic objects of atomic physics” [1] edited recently contains some information on the above-listed objects of the atomic physics. This textbook can be considered as a supplement to classic courses of atomic physics teaching in technical universities.

  1. Key insights on the structural characterization of textured Er{sub 2}O{sub 3}-ZrO{sub 2} nano-oxides prepared by a surfactant-free solvothermal route

    Energy Technology Data Exchange (ETDEWEB)

    Julian-Lopez, Beatriz, E-mail: julian@qio.uji.es [Departamento de Quimica Inorganica y Organica, Universitat Jaume I, Avda. Vicente Sos Baynat s/n, 12071 Castellon (Spain); Luz, Veronica de la; Gonell, Francisco; Cordoncillo, Eloisa [Departamento de Quimica Inorganica y Organica, Universitat Jaume I, Avda. Vicente Sos Baynat s/n, 12071 Castellon (Spain); Lopez-Haro, Miguel; Calvino, Jose J. [Departamento de Ciencia de los Materiales e Ingenieria Metalurgica y Quimica Inorganica, Facultad de Ciencias, Universidad de Cadiz, Campus Rio San Pedro, Puerto Real, 11510 Cadiz (Spain); Escribano, Purificacion [Departamento de Quimica Inorganica y Organica, Universitat Jaume I, Avda. Vicente Sos Baynat s/n, 12071 Castellon (Spain)

    2012-04-05

    Highlights: Black-Right-Pointing-Pointer Structural resolution of fluorite vs. pyrochlore in small nanocrystals. Black-Right-Pointing-Pointer Simple template-free solvothermal synthesis of Er{sub 2}O{sub 3}-ZrO{sub 2} nanooxides. Black-Right-Pointing-Pointer Good control over size, morphology and surface properties (280 m{sup 2} g{sup -1}). - Abstract: Zirconia-mixed oxides can exhibit cubic fluorite and pyrochlore structure. Their discrimination is not easy in nanooxides with a crystal size close to that of a few unit cells. In this work, high resolution transmission electron microscopy (HRTEM) has been employed to provide key insights on the structural characterization of a nanometric and porous mixed Er{sub 2}O{sub 3}-ZrO{sub 2} oxide. The material was prepared by a simple template-free solvothermal route that provided nanocrystalline powders at low temperature (170 Degree-Sign C) with spherical morphology, and high surface area ({approx}280 m{sup 2} g{sup -1}). The porosity was mainly originated from the assembling of organic complexing agents used in the synthesis to limit the crystal growth and to control hydrolysis and condensation reaction rates. The samples were characterized by thermal analysis, X-ray diffraction, scanning electron microscopy and N{sub 2} adsorption measurements. A detailed study by HRTEM was conducted on microtomed samples. It was observed that the material was made of nanocrystals packed into spherical agglomerates. HRTEM simulations indicated that it is not possible to identify the pyrochlore phase in nanoparticles with diameter below 2 nm. In our samples, the analysis of the HRTEM lattice images by means of fast Fourier transform (FFT) techniques revealed well defined spots that can be assigned to different planes of a cubic fluorite-type phase, even in the raw material. Raman spectroscopy was also a powerful technique to elucidate the crystalline phase of the materials with the smallest nanoparticles. HREM and Raman results evidenced

  2. Optically polarized atoms understanding light-atom interactions

    CERN Document Server

    Auzinsh, Marcis; Rochester, Simon M

    2010-01-01

    This book is addressed at upper-level undergraduate and graduate students involved in research in atomic, molecular, and optical Physics. It will also be useful to researchers practising in this field. It gives an intuitive, yet sufficiently detailed and rigorous introduction to light-atom interactions with a particular emphasis on the symmetry aspects of the interaction, especially those associated with the angular momentum of atoms and light. The book will enable readers to carryout practical calculations on their own, and is richly illustrated with examples drawn from current research topic

  3. Atom interferometry with trapped Bose-Einstein condensates: impact of atom-atom interactions

    International Nuclear Information System (INIS)

    Grond, Julian; Hohenester, Ulrich; Mazets, Igor; Schmiedmayer, Joerg

    2010-01-01

    Interferometry with ultracold atoms promises the possibility of ultraprecise and ultrasensitive measurements in many fields of physics, and is the basis of our most precise atomic clocks. Key to a high sensitivity is the possibility to achieve long measurement times and precise readout. Ultracold atoms can be precisely manipulated at the quantum level and can be held for very long times in traps; they would therefore be an ideal setting for interferometry. In this paper, we discuss how the nonlinearities from atom-atom interactions, on the one hand, allow us to efficiently produce squeezed states for enhanced readout and, on the other hand, result in phase diffusion that limits the phase accumulation time. We find that low-dimensional geometries are favorable, with two-dimensional (2D) settings giving the smallest contribution of phase diffusion caused by atom-atom interactions. Even for time sequences generated by optimal control, the achievable minimal detectable interaction energy ΔE min is of the order of 10 -4 μ, where μ is the chemical potential of the Bose-Einstein condensate (BEC) in the trap. From these we have to conclude that for more precise measurements with atom interferometers, more sophisticated strategies, or turning off the interaction-induced dephasing during the phase accumulation stage, will be necessary.

  4. Atomic energy review

    International Nuclear Information System (INIS)

    1971-01-01

    The ATOMIC ENERGY REVIEW (AER), a periodical started in 1963 in accordance with the recommendation made by the Scientific Advisory Committee, is now preparing for its tenth year of publication. The journal appears quarterly (ca 900 pages/year) and occasionally has special issues and supplements. From 1963 to 1971 AER developed into an important international high-standard scientific journal which keeps scientists in Member States informed on progress in various fields of nuclear energy. The Agency's specific role of helping 'developing countries to further their science and education' is reflected in the publication policy of the journal. The subject scope of AER, which was determined at the journal's inception, is very broad. It covers topics in experimental and theoretical physics, nuclear electronics and equipment, physics and technology of reactors and reactor materials and fuels, radio-chemistry, and industrial, medical and other uses of radioisotopes. In other words, almost any subject related to the peaceful application of nuclear energy can qualify for inclusion. Specifically, at any particular time the selection criteria for topics are influenced by the Agency's current programme and interests. AER carries comprehensive review articles, critical state-of-the-art and current awareness surveys, and reports on the important meetings organized or sponsored by the Agency. The following four subsections gradually became necessary to do justice to this variety of material: 'Reviews' proper, 'Current Research and Development', 'Special Item' and 'Conferences and Symposia'. Apart from the conference reports, one hundred and twenty-five reviews, almost all of which were published in English to make them accessible to a wide public, have so far been published

  5. Giant light enhancement in atomic clusters

    International Nuclear Information System (INIS)

    Gadomsky, O. N.; Gadomskaya, I. V.; Altunin, K. K.

    2009-01-01

    We show that the polarizing effect of the atoms in an atomic cluster can lead to full compensation of the radiative damping of excited atomic states, a change in the sign of the dispersion of the atomic polarizability, and giant light enhancement by the atomic cluster.

  6. Atomization of volatile compounds for atomic absorption and atomic fluorescence spectrometry: On the way towards the ideal atomizer

    International Nuclear Information System (INIS)

    Dedina, Jiri

    2007-01-01

    This review summarizes and discusses the individual atomizers of volatile compounds. A set of criteria important for analytical praxis is used to rank all the currently existing approaches to the atomization based on on-line atomization for atomic absorption (AAS) and atomic fluorescence spectrometry (AFS) as well as on in-atomizer trapping for AAS. Regarding on-line atomization for AAS, conventional quartz tubes are currently the most commonly used devices. They provide high sensitivity and low baseline noise. Running and investment costs are low. The most serious disadvantage is the poor resistance against atomization interferences and often unsatisfactory linearity of calibration graphs. Miniature diffusion flame (MDF) is extremely resistant to interferences, simple, cheap and user-friendly. Its essential disadvantage is low sensitivity. A novel device, known as a multiatomizer, was designed to overcome disadvantages of previous atomizers. It matches performance of conventional quartz tubes in terms of sensitivity and baseline noise as well as in running and investment costs. The multiatomizer, however, provides much better (i) resistance against atomization interferences and (ii) linearity of calibration graphs. In-atomizer trapping enhances the sensitivity of the determination and eliminates the effect of the generation kinetics and of surges in gas flow on the signal shape. This is beneficial for the accuracy of the determination. It could also be an effective tool for reducing some interferences in the liquid phase. In-situ trapping in graphite furnaces (GF) is presently by far the most popular approach to the in-atomizer trapping. Its resistance against interferences is reasonably good and it can be easily automated. In-situ trapping in GF is a mature method well established in various application fields. These are the reasons to rank in-situ trapping in GF as currently the most convenient approach to hydride atomization for AAS. The recently suggested

  7. PubChem atom environments.

    Science.gov (United States)

    Hähnke, Volker D; Bolton, Evan E; Bryant, Stephen H

    2015-01-01

    Atom environments and fragments find wide-spread use in chemical information and cheminformatics. They are the basis of prediction models, an integral part in similarity searching, and employed in structure search techniques. Most of these methods were developed and evaluated on the relatively small sets of chemical structures available at the time. An analysis of fragment distributions representative of most known chemical structures was published in the 1970s using the Chemical Abstracts Service data system. More recently, advances in automated synthesis of chemicals allow millions of chemicals to be synthesized by a single organization. In addition, open chemical databases are readily available containing tens of millions of chemical structures from a multitude of data sources, including chemical vendors, patents, and the scientific literature, making it possible for scientists to readily access most known chemical structures. With this availability of information, one can now address interesting questions, such as: what chemical fragments are known today? How do these fragments compare to earlier studies? How unique are chemical fragments found in chemical structures? For our analysis, after hydrogen suppression, atoms were characterized by atomic number, formal charge, implicit hydrogen count, explicit degree (number of neighbors), valence (bond order sum), and aromaticity. Bonds were differentiated as single, double, triple or aromatic bonds. Atom environments were created in a circular manner focused on a central atom with radii from 0 (atom types) up to 3 (representative of ECFP_6 fragments). In total, combining atom types and atom environments that include up to three spheres of nearest neighbors, our investigation identified 28,462,319 unique fragments in the 46 million structures found in the PubChem Compound database as of January 2013. We could identify several factors inflating the number of environments involving transition metals, with many

  8. Parental insightfulness: retrospect and prospect.

    Science.gov (United States)

    Koren-Karie, Nina; Oppenheim, David

    2018-06-01

    We open this introductory paper to the special issue with the theoretical and clinical roots of the insightfulness concept. Next, the Insightfulness Assessment (IA) is presented, followed by a review of key empirical findings supporting the IA. The central points in the papers in this special issue are reviewed next. These include the use of the IA with parents of children ranging in age from infancy to adolescence, its applicability outside the parent-child relationship (e.g. insightfulness toward a close friend), its use with high-risk mothers, and the usefulness of insightfulness both as a continuous and a categorical measure. The clinical applications of the IA are discussed, and we close with future directions for IA research.

  9. Spontaneous emission by moving atoms

    International Nuclear Information System (INIS)

    Meystre, P.; Wilkens, M.

    1994-01-01

    It is well known that spontaneous emission is not an intrinsic atomic property, but rather results from the coupling of the atom to the vacuum modes of the electromagnetic field. As such, it can be modified by tailoring the electromagnetic environment into which the atom can radiate. This was already realized by Purcell, who noted that the spontaneous emission rate can be enhanced if the atom placed inside a cavity is resonant with one of the cavity is resonant with one of the cavity modes, and by Kleppner, who discussed the opposite case of inhibited spontaneous emission. It has also been recognized that spontaneous emission need not be an irreversible process. Indeed, a system consisting of a single atom coupled to a single mode of the electromagnetic field undergoes a periodic exchange of excitation between the atom and the field. This periodic exchange remains dominant as long as the strength of the coupling between the atom and a cavity mode is itself dominant. 23 refs., 6 figs

  10. Atom Optics in a Nutshell

    Science.gov (United States)

    Meystre, Pierre

    This chapter presents a brief introduction to atom optics, assuming only a basic knowledge of elementary physics ideas such as conservation of energy and conservation of momentum, and making only limited use of elementary algebra. Starting from a historical perspective we introduce the idea of wave-particle duality, a fundamental tenet of quantum mechanics that teaches us that atoms, just like light, behave sometimes as waves, and sometimes as particles. It is this profound but counter-intuitive property that allows one to do with atoms much of what is familiar from conventional optics. However, because in contrast to photons atoms have a mass, there are also fundamental differences between the two that have important consequences. In particular this property opens up a number of applications that are ill-suited for conventional optical methods. After explaining why it is particularly advantageous to work at temperatures close to absolute zero to benefit most readily from the wave nature of atoms we discuss several of these applications, concentrating primarily on the promise of atom microscopes and atom interferometers in addressing fundamental and extraordinarily challenging questions at the frontier of current physics knowledge.

  11. Classical approach in atomic physics

    International Nuclear Information System (INIS)

    Solov'ev, E.A.

    2011-01-01

    The application of a classical approach to various quantum problems - the secular perturbation approach to quantization of a hydrogen atom in external fields and a helium atom, the adiabatic switching method for calculation of a semiclassical spectrum of a hydrogen atom in crossed electric and magnetic fields, a spontaneous decay of excited states of a hydrogen atom, Gutzwiller's approach to Stark problem, long-lived excited states of a helium atom discovered with the help of Poincare section, inelastic transitions in slow and fast electron-atom and ion-atom collisions - is reviewed. Further, a classical representation in quantum theory is discussed. In this representation the quantum states are treated as an ensemble of classical states. This approach opens the way to an accurate description of the initial and final states in classical trajectory Monte Carlo (CTMC) method and a purely classical explanation of tunneling phenomenon. The general aspects of the structure of the semiclassical series such as renormalization group symmetry, criterion of accuracy and so on are reviewed as well. (author)

  12. A linear atomic quantum coupler

    Energy Technology Data Exchange (ETDEWEB)

    El-Orany, Faisal A A [Department of Mathematics and computer Science, Faculty of Science, Suez Canal University 41522, Ismailia (Egypt); Wahiddin, M R B, E-mail: el_orany@hotmail.co, E-mail: faisal.orany@mimos.m, E-mail: mridza@mimos.m [Cyberspace Security Laboratory, MIMOS Berhad, Technology Park Malaysia, 57000 Kuala Lumpur (Malaysia)

    2010-04-28

    In this paper we develop the notion of the linear atomic quantum coupler. This device consists of two modes propagating into two waveguides, each of which includes a localized atom. These waveguides are placed close enough to allow exchange of energy between them via evanescent waves. Each mode interacts with the atom in the same waveguide in the standard way as the Jaynes-Cummings model (JCM) and with the atom-mode system in the second waveguide via the evanescent wave. We present the Hamiltonian for this system and deduce its wavefunction. We investigate the atomic inversions and the second-order correlation function. In contrast to the conventional coupler the atomic quantum coupler is able to generate nonclassical effects. The atomic inversions can exhibit a long revival-collapse phenomenon as well as subsidiary revivals based on the competition among the switching mechanisms in the system. Finally, under certain conditions the system can yield the results of the two-mode JCM.

  13. Electronic structure of atoms: atomic spectroscopy information system

    International Nuclear Information System (INIS)

    Kazakov, V V; Kazakov, V G; Kovalev, V S; Meshkov, O I; Yatsenko, A S

    2017-01-01

    The article presents a Russian atomic spectroscopy, information system electronic structure of atoms (IS ESA) (http://grotrian.nsu.ru), and describes its main features and options to support research and training. The database contains over 234 000 records, great attention paid to experimental data and uniform filling of the database for all atomic numbers Z, including classified levels and transitions of rare earth and transuranic elements and their ions. Original means of visualization of scientific data in the form of spectrograms and Grotrian diagrams have been proposed. Presentation of spectral data in the form of interactive color charts facilitates understanding and analysis of properties of atomic systems. The use of the spectral data of the IS ESA together with its functionality is effective for solving various scientific problems and training of specialists. (paper)

  14. Electronic structure of atoms: atomic spectroscopy information system

    Science.gov (United States)

    Kazakov, V. V.; Kazakov, V. G.; Kovalev, V. S.; Meshkov, O. I.; Yatsenko, A. S.

    2017-10-01

    The article presents a Russian atomic spectroscopy, information system electronic structure of atoms (IS ESA) (http://grotrian.nsu.ru), and describes its main features and options to support research and training. The database contains over 234 000 records, great attention paid to experimental data and uniform filling of the database for all atomic numbers Z, including classified levels and transitions of rare earth and transuranic elements and their ions. Original means of visualization of scientific data in the form of spectrograms and Grotrian diagrams have been proposed. Presentation of spectral data in the form of interactive color charts facilitates understanding and analysis of properties of atomic systems. The use of the spectral data of the IS ESA together with its functionality is effective for solving various scientific problems and training of specialists.

  15. Franchise Business Model: Theoretical Insights

    OpenAIRE

    Levickaitė, Rasa; Reimeris, Ramojus

    2010-01-01

    The article is based on literature review, theoretical insights, and deals with the topic of franchise business model. The objective of the paper is to analyse peculiarities of franchise business model and its developing conditions in Lithuania. The aim of the paper is to make an overview on franchise business model and its environment in Lithuanian business context. The overview is based on international and local theoretical insights. In terms of practical meaning, this article should be re...

  16. The atomic structure of polar and non-polar InGaN quantum wells and the green gap problem

    Energy Technology Data Exchange (ETDEWEB)

    Humphreys, C.J., E-mail: colin.humphreys@msm.cam.ac.uk [Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom); Griffiths, J.T., E-mail: jg641@cam.ac.uk [Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom); Tang, F., E-mail: ft274@cam.ac.uk [Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom); Oehler, F., E-mail: fabrice.oehler@lpn.cnrs.fr [CNRS/C2N, Paris Sud University, Route de Nozay, 91460 Marcoussis (France); Findlay, S.D., E-mail: scott.findlay@monash.edu [School of Physics and Astronomy, Monash University, Victoria 3800 (Australia); Zheng, C., E-mail: changlin.zheng@monash.edu [Monash Centre for Electron Microscopy, Monash University, Victoria 3800 (Australia); Etheridge, J., E-mail: joanne.etheridge@mcem.monash.edu [Department of Materials Science and Engineering, Monash University, Victoria 3800 (Australia); Martin, T.L., E-mail: tomas.martin@materials.ox.ac.uk [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Bagot, P.A.J., E-mail: paul.bagot@materials.ox.ac.uk [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Moody, M.P., E-mail: michael.moody@materials.ox.ac.uk [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Sutherland, D., E-mail: danny.sutherland@manchester.ac.uk [School of Physics and Astronomy, Photon Science Institute, University of Manchester, Manchester M13 9PL (United Kingdom); Dawson, P., E-mail: philip.dawson@manchester.ac.uk [School of Physics and Astronomy, Photon Science Institute, University of Manchester, Manchester M13 9PL (United Kingdom); Schulz, S., E-mail: stefan.schulz@tyndall.ie [Tyndall National Institute, Lee Maltings Complex, Dyke Parade, Cork (Ireland); and others

    2017-05-15

    Highlights: • We have studied the atomic structure of polar and non-polar InGaN quantum wells. • The non-polar (11-20) InGaN quantum wells contain indium-rich clusters, unlike the polar (0001) quantum wells. • The electrons and holes in the quantum wells are localised by different mechanisms. - Abstract: We have used high resolution transmission electron microscopy (HRTEM), aberration-corrected quantitative scanning transmission electron microscopy (Q-STEM), atom probe tomography (APT) and X-ray diffraction (XRD) to study the atomic structure of (0001) polar and (11-20) non-polar InGaN quantum wells (QWs). This paper provides an overview of the results. Polar (0001) InGaN in QWs is a random alloy, with In replacing Ga randomly. The InGaN QWs have atomic height interface steps, resulting in QW width fluctuations. The electrons are localised at the top QW interface by the built-in electric field and the well-width fluctuations, with a localisation energy of typically 20 meV. The holes are localised near the bottom QW interface, by indium fluctuations in the random alloy, with a localisation energy of typically 60 meV. On the other hand, the non-polar (11-20) InGaN QWs contain nanometre-scale indium-rich clusters which we suggest localise the carriers and produce longer wavelength (lower energy) emission than from random alloy non-polar InGaN QWs of the same average composition. The reason for the indium-rich clusters in non-polar (11-20) InGaN QWs is not yet clear, but may be connected to the lower QW growth temperature for the (11-20) InGaN QWs compared to the (0001) polar InGaN QWs.

  17. Atomization mechanisms for barium in furnace atomic absorption spectrometry

    International Nuclear Information System (INIS)

    Styris, D.L.

    1984-01-01

    Atomic absorption spectrometry and mass spectrometry are used simultaneously in order to elucidate atomization mechanisms of barium dichloride in pyrolytic graphite, vitreous carbon, and tantalum furnaces. Gas-phase barium dicarbide is observed to appear concurrently with the free barium. Barium oxide and barium dihydroxide precursors appear with the chlorides. Surface reactions involving species that are absorbed on the various furnaces are postulated to explain the appearances of the species that are observed in the gas phase. 49 references, 4 figures, 1 table

  18. Observation of relativistic antihydrogen atoms

    International Nuclear Information System (INIS)

    Blanford, Glenn DelFosse

    1998-01-01

    An observation of relativistic antihydrogen atoms is reported in this dissertation. Experiment 862 at Fermi National Accelerator Laboratory observed antihydrogen atoms produced by the interaction of a circulating beam of high momentum (3 0 production is outlined within. The cross section corresponds to the process where a high momentum antiproton causes e + e - pair creation near a nucleus with the e + being captured by the antiproton. Antihydrogen is the first atom made exclusively of antimatter to be detected. The observation experiment's results are the first step towards an antihydrogen spectroscopy experiment which would measure the n = 2 Lamb shift and fine structure

  19. Quantum Electronics for Atomic Physics

    CERN Document Server

    Nagourney, Warren

    2010-01-01

    Quantum Electronics for Atomic Physics provides a course in quantum electronics for researchers in atomic physics. The book covers the usual topics, such as Gaussian beams, cavities, lasers, nonlinear optics and modulation techniques, but also includes a number of areas not usually found in a textbook on quantum electronics. It includes such practical matters as the enhancement of nonlinear processes in a build-up cavity, impedance matching into a cavity, laser frequencystabilization (including servomechanism theory), astigmatism in ring cavities, and atomic/molecular spectroscopic techniques

  20. Correlations between interacting Rydberg atoms

    DEFF Research Database (Denmark)

    Paris-Mandoki, Asaf; Braun, Christoph; Hofferberth, Sebastian

    2018-01-01

    This paper is a short introduction to Rydberg physics and quantum nonlinear optics using Rydberg atoms. It has been prepared as a compliment to a series of lectures delivered during the Latin American School of Physics "Marcos Moshinsky" 2017. We provide a short introduction to the properties...... of individual Rydberg atoms and discuss in detail how the interaction potential between Rydberg atom pairs is calculated. We then discuss how this interaction gives rise to the Rydberg blockade mechanism. With the aid of hallmark experiments in the field applications of the blockade for creating correlated...

  1. Mechanical filter for alkali atoms

    CERN Document Server

    Toporkov, D K

    2000-01-01

    A device for separating gases of different mass is discussed. Such a device could be used in a laser-driven spin exchange source of polarized hydrogen atoms to reduce the contamination of alkali atoms. A Monte Carlo simulation has shown that the suggested apparatus based on a commercial turbo pump could reduce by a factor of 10-15 the concentration of the alkali-metal atoms in the hydrogen flow from a laser driven polarized source. This would greatly enhance the effective polarization in hydrogen targets.

  2. Detecting device of atomic probe

    International Nuclear Information System (INIS)

    Nikonenkov, N.V.

    1979-01-01

    Operation of an atomic-probe recording device is discussed in detail and its flowsheet is given. The basic elements of the atomic-probe recording device intented for microanalysis of metals and alloys in an atomic level are the storage oscillograph with a raster-sweep unit, a two-channel timer using frequency meters, a digital printer, and a control unit. The digital printer records information supplied by four digital devices (two frequency meters and two digital voltmeters) in a four-digit binary-decimal code. The described device provides simultaneous recording of two ions produced per one vaporation event

  3. Sample Preprocessing For Atomic Spectrometry

    International Nuclear Information System (INIS)

    Kim, Sun Tae

    2004-08-01

    This book gives descriptions of atomic spectrometry, which deals with atomic absorption spectrometry such as Maxwell-Boltzmann equation and Beer-Lambert law, atomic absorption spectrometry for solvent extraction, HGAAS, ETASS, and CVAAS and inductively coupled plasma emission spectrometer, such as basic principle, generative principle of plasma and device and equipment, and interferences, and inductively coupled plasma mass spectrometry like device, pros and cons of ICP/MS, sample analysis, reagent, water, acid, flux, materials of experiments, sample and sampling and disassembling of sample and pollution and loss in open system and closed system.

  4. Review of atomic mass formula

    Energy Technology Data Exchange (ETDEWEB)

    Tachibana, Takahiro [Waseda Univ., Tokyo (Japan). Advanced Research Center for Science and Engineering

    1997-07-01

    Wapstra and Audi`s Table is famous for evaluation of experimental data of atomic nuclear masses (1993/1995 version) which estimated about 2000 kinds of nuclei. The error of atomic mass of formula is 0.3 MeV-0.8 MeV. Four kinds of atomic mass formula: JM (Jaenecke and Masson), TUYY (Tachibana, Uno, Yamada and Yamada), FRDM (Moeller, Nix, Myers and Swiatecki) and ETFSI (Aboussir, Pearson, Dutta and Tondeur) and their properties (number of parameter and error etc.) were explained. An estimation method of theoretical error of mass formula was presented. It was estimated by the theoretical error of other surrounding nuclei. (S.Y.)

  5. Fundamentals in hadronic atom theory

    CERN Document Server

    Deloff, A

    2003-01-01

    Hadronic atoms provide a unique laboratory for studying hadronic interactions essentially at threshold. This text is the first book-form exposition of hadronic atom theory with emphasis on recent developments, both theoretical and experimental. Since the underlying Hamiltonian is a non-self-adjoined operator, the theory goes beyond traditional quantum mechanics and this book covers topics that are often glossed over in standard texts on nuclear physics. The material contained here is intended for the advanced student and researcher in nuclear, atomic or elementary-particle physics. A good know

  6. Atomic collisions involving pulsed positrons

    DEFF Research Database (Denmark)

    Merrison, J. P.; Bluhme, H.; Field, D.

    2000-01-01

    Conventional slow positron beams have been widely and profitably used to study atomic collisions and have been instrumental in understanding the dynamics of ionization. The next generation of positron atomic collision studies are possible with the use of charged particle traps. Not only can large...... instantaneous intensities be achieved with in-beam accumulation, but more importantly many orders of magnitude improvement in energy and spatial resolution can be achieved using positron cooling. Atomic collisions can be studied on a new energy scale with unprecedented precion and control. The use...

  7. AtomPy: an open atomic-data curation environment

    Science.gov (United States)

    Bautista, Manuel; Mendoza, Claudio; Boswell, Josiah S; Ajoku, Chukwuemeka

    2014-06-01

    We present a cloud-computing environment for atomic data curation, networking among atomic data providers and users, teaching-and-learning, and interfacing with spectral modeling software. The system is based on Google-Drive Sheets, Pandas (Python Data Analysis Library) DataFrames, and IPython Notebooks for open community-driven curation of atomic data for scientific and technological applications. The atomic model for each ionic species is contained in a multi-sheet Google-Drive workbook, where the atomic parameters from all known public sources are progressively stored. Metadata (provenance, community discussion, etc.) accompanying every entry in the database are stored through Notebooks. Education tools on the physics of atomic processes as well as their relevance to plasma and spectral modeling are based on IPython Notebooks that integrate written material, images, videos, and active computer-tool workflows. Data processing workflows and collaborative software developments are encouraged and managed through the GitHub social network. Relevant issues this platform intends to address are: (i) data quality by allowing open access to both data producers and users in order to attain completeness, accuracy, consistency, provenance and currentness; (ii) comparisons of different datasets to facilitate accuracy assessment; (iii) downloading to local data structures (i.e. Pandas DataFrames) for further manipulation and analysis by prospective users; and (iv) data preservation by avoiding the discard of outdated sets.

  8. Mechanism of yttrium atom formation in electrothermal atomization from metallic and metal-carbide surfaces of a heated graphite atomizer in atomic absorption spectrometry

    International Nuclear Information System (INIS)

    Wahab, H.S.; Chakrabarti, C.L.

    1981-01-01

    Mechanism of Y atom formation from pyrocoated graphite, tantalum and tungsten metal surfaces of a graphite tube atomizer has been studied and a mechanism for the formation for Y atoms is proposed for the first time. (author)

  9. Absorption properties of identical atoms

    International Nuclear Information System (INIS)

    Sancho, Pedro

    2013-01-01

    Emission rates and other optical properties of multi-particle systems in collective and entangled states differ from those in product ones. We show the existence of similar effects in the absorption probabilities for (anti)symmetrized states of two identical atoms. The effects strongly depend on the overlapping between the atoms and differ for bosons and fermions. We propose a viable experimental verification of these ideas. -- Highlights: •The absorption rates of a pair of identical atoms in product and (anti)symmetrized states are different. •The modifications of the optical properties are essentially determined by the overlapping between the atoms. •The absorption properties differ, in some cases, for bosons and fermions

  10. Atomic layer deposition for semiconductors

    CERN Document Server

    Hwang, Cheol Seong

    2014-01-01

    This edited volume discusses atomic layer deposition (ALD) for all modern semiconductor devices, moving from the basic chemistry of ALD and modeling of ALD processes to sections on ALD for memories, logic devices, and machines.

  11. Quantum Repeaters and Atomic Ensembles

    DEFF Research Database (Denmark)

    Borregaard, Johannes

    a previous protocol, thereby enabling fast local processing, which greatly enhances the distribution rate. We then move on to describe our work on improving the stability of atomic clocks using entanglement. Entanglement can potentially push the stability of atomic clocks to the so-called Heisenberg limit...... and allows for near-Heisenberg limited stability of atomic clocks. Furthermore, we describe how the operation of a clock can be altered to gain an exponential improvement of the stability even without entanglement. In the next part of the thesis, we describe our work on a novel type of heralded quantum gates...... temperature quantum memories and single photon sources. We have introduced a novel concept of motional averaging, which can be used in room-temperature systems, where fluctuations due to thermal motion is an issue. In particular, we have considered a system based on microcells filled with Cs-atoms, which can...

  12. Scattering of highly excited atoms

    International Nuclear Information System (INIS)

    Raith, W.

    1980-01-01

    Experimental methods to excite atomic beams into Rydberg states and the first results of collision experiments with such beams are reported. For further information see hints under relevant topics. (orig.) [de

  13. Neutral atom traps of radioactives

    International Nuclear Information System (INIS)

    Behr, J.A.

    2003-01-01

    Neutral atoms trapped with modern laser cooling techniques offer the promise of improving several broad classes of experiments with radioactive isotopes. In nuclear β decay, neutrino spectroscopy from beta-recoil coincidences, along with highly polarized samples, enable experiments to search for non-Standard Model interactions, test whether parity symmetry is maximally violated, and search for new sources of time reversal violation. Ongoing efforts at TRIUMF, Los Alamos and Berkeley will be highlighted. The traps also offer bright sources for Doppler-free spectroscopy, particularly in high-Z atoms where precision measurements could measure the strength of weak neutral nucleon-nucleon and electron-nucleon interactions. Physics with francium atoms has been vigorously pursued at Stony Brook. Several facilities plan work with radioactive atom traps; concrete plans and efforts at KVI Groningen and Legnaro will be among those summarized. Contributions to the multidisciplinary field of trace analysis will be left up to other presenters

  14. Neutral atom traps of radioactives

    CERN Document Server

    Behr, J A

    2003-01-01

    Neutral atoms trapped with modern laser cooling techniques offer the promise of improving several broad classes of experiments with radioactive isotopes. In nuclear beta decay, neutrino spectroscopy from beta-recoil coincidences, along with highly polarized samples, enable experiments to search for non-Standard Model interactions, test whether parity symmetry is maximally violated, and search for new sources of time reversal violation. Ongoing efforts at TRIUMF, Los Alamos and Berkeley will be highlighted. The traps also offer bright sources for Doppler-free spectroscopy, particularly in high-Z atoms where precision measurements could measure the strength of weak neutral nucleon-nucleon and electron-nucleon interactions. Physics with francium atoms has been vigorously pursued at Stony Brook. Several facilities plan work with radioactive atom traps; concrete plans and efforts at KVI Groningen and Legnaro will be among those summarized. Contributions to the multidisciplinary field of trace analysis will be left...

  15. Dependency Ordering of Atomic Observables

    Science.gov (United States)

    Cīrulis, Jānis

    2015-12-01

    The notion of atomic observable was introduced by S.Gudder for effect test spaces in 1997. In this paper an observable is a σ-homomorphism from the Borel algebra on a line to some logic. Roughly, an observable on a logic is atomic, if it is completely determined by its restriction to one-element subsets of its point spectrum. In particular, every discrete observable is atomic. We study some elementary properties of such observables, and discuss a possible notion of functional dependency between them. Algebraically, a dependency is a certain preorder relation on the set of all atomic observables, which induces an order relation on the set of all maximal orthogonal subsets of the logic. Several properties, as well as characteristics in terms of the underlying logic, of these relations are stated.

  16. Atom beams split by gentle persuasion

    International Nuclear Information System (INIS)

    Pool, R.

    1994-01-01

    Two different research teams have taken a big step toward atom interferometry. They have succeeded in splitting atomic beams by using atoms in spin states that neither absorb nor reemit laser light. By proper adjustment of experimental conditions, atoms are changed from one spin state to another, without passing through the intermediary excited state. The atoms in essence absorb momentum from the laser photons, without absorption or emission of photons. The change in momentum deflects atoms in the proper spin state

  17. Muonic atoms with vacant electron shells

    International Nuclear Information System (INIS)

    Bacher, R.; Gotta, D.; Simons, L.M.; Missimer, J.; Mukhopadhyay, N.C.

    1985-01-01

    We show that the cascade in muonic atoms with Z<20 ejects sufficient atomic electrons to ionize an isolated muonic atom completely. In gases, the rates with which electrons refill the atomic shell can be accurately deduced from measured and calculated electron transfer cross sections. Thus, we can conclude that completely ionized muonic atoms can be prepared in gases, and that they remain isolated for long enough times at attainable pressures to facilitate studies of fundamental interactions in muonic atoms

  18. Spin noise measurement with diamagnetic atoms

    International Nuclear Information System (INIS)

    Takeuchi, M.; Ichihara, S.; Takano, T.; Kumakura, M.; Takahashi, Y.

    2007-01-01

    We report the measurement of the atomic spin noise of the diamagnetic atom ytterbium (Yb). Yb has various merits for utilizing the quantum nature of the atomic spin ensemble compared with the paramagnetic atoms used in all previous experiments. From the magnitude of the noise level and dependence on the detuning, we concluded that we succeeded in the measurement of 171 Yb atomic spin noise in an atomic beam

  19. Photoionization of atoms and molecules

    International Nuclear Information System (INIS)

    Samson, J.A.R.

    1976-01-01

    A literature review on the present state of knowledge in photoionization is presented. Various experimental techniques that have been developed to study photoionization, such as fluorescence and photoelectron spectroscopy, mass spectroscopy, are examined. Various atoms and molecules were chosen to illustrate these techniques, specifically helium and xenon atoms and hydrogen molecules. Specialized photoionization such as in positive and negative ions, excited states, and free radicals is also treated. Absorption cross sections and ionization potentials are also discussed

  20. Chain formation of metal atoms

    DEFF Research Database (Denmark)

    Bahn, Sune Rastad; Jacobsen, Karsten Wedel

    2001-01-01

    The possibility of formation of single-atomic chains by manipulation of nanocontacts is studied for a selection of metals (Ni, Pd, Pt, Cu, Ag, Au). Molecular dynamics simulations show that the tendency for chain formation is strongest for Au and Pt. Density functional theory calculations indicate...... that the metals which form chains exhibit pronounced many-atom interactions with strong bonding in low coordinated systems....