WorldWideScience

Sample records for atom hrtem insights

  1. 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.

  2. HRTEM and EELS characterization of atomic and electronic structures in Cu/α-Al2O3 interfaces

    International Nuclear Information System (INIS)

    Interfacial atomic structures of Cu/Al2O3(0001) and Cu/Al2O3(1-bar 1-bar 2-bar -bar 0) prepared by the pulsed-laser deposition technique were characterized by high-resolution transmission electron microscopy (HRTEM). It was found that (111) and (001) planes of Cu were epitaxially oriented to Al2O3(0001) and Al2O3(1-bar 1-bar 2-bar -bar 0) planes, respectively. Chemical bonding states at the interfaces were analysed by electron energy-loss spectroscopy (EELS). In oxygen-K edge energy-loss near-edge structure (O-K ELNES) of the Cu/Al2O3(0001) and Cu/Al2O3(1-bar 1-bar 2-bar -bar 0) interfaces, a shoulder peak appeared at the lower energy side of the main peak. This indicates that Cu-O interactions were formed across these Cu/Al2O3 interfaces. In fact, the simulated HRTEM images based on the O-terminated interface models agreed well with the experimental ones. It can be concluded that the O-terminated interfaces were formed in the present Cu/Al2O3 interfaces

  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)

    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 InxGa1-xN, 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 InxGa1-xN 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. 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)

    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)1.14NbS2 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)1.14NbS2 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.

  6. HRTEM analysis of nanodomain textures in PMN

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Xudong; Qian, Hua; Peng Julin; Bursill, L.A.

    1995-10-01

    Chemical domain textures of PMN are modelled using next-nearest-neighbour Ising (NNNI) models and Monte Carlo methods. These simulations allow us to understand and quantify the local structures of clusters of Nb and Mg atoms and how these interact to form chemical domain walls and other configuration including charged chemical defects. This model for the B-site distribution is used for image simulations. Both HRTEM many-beam bright-and dark single-beam TEM images are obtained and compared with the experimental images. The final result is a realistic atomic model for the Nb, Mg distribution of PMN. 10 refs., 6 figs.

  7. The S-state model: a work horse for HRTEM

    Energy Technology Data Exchange (ETDEWEB)

    Geuens, P.; Dyck, D. van

    2002-12-15

    The S-state model describes the dynamical scattering of electrons in a specimen foil, consisting of atom columns parallel to the beam direction, such as a crystal or a particular crystal defect. In this model the electrons are considered to be trapped in the electrostatic potential of an atom column, in which it scatters dynamically. This picture allows physical insight, and it explains why a one-to-one correspondence is maintained between the exit wave and the projected structure, even in case of strong dynamical scattering. Furthermore the model can be parameterised in a simple closed analytical form. Apart from the computational advantages, the S-state model proves to be very useful to deduce the projected structure directly from the exit wave, so as to 'invert' the dynamical scattering. In this paper the validity of the S-state model, is evaluated in much depth by a proper quantum mechanical treatment. The analytical parameterisation of the 1S eigenfunction and eigenenergy is discussed. It is shown that the method, even in case of small tilts, is valid for most thicknesses, currently used in HRTEM studies. Even for closely spaced atom columns, such as the dumbbells in Si [1 1 0], Sn [1 1 0] and GaN [1 1 0], the positions of the atom columns can be deduced with an accuracy of a few pm.

  8. Atomic resolution imaging of oxygen atoms close to heavy atoms by HRTEM and ED, using the superconductor SmFeAsO0.85F0.15 as an example.

    Science.gov (United States)

    Wang, Yumei; Ge, Binghui; Che, Guangcan

    2015-04-01

    Imaging of light atoms has always been a challenge in high-resolution electron microscopy. Image resolution is mainly limited by lens aberrations, especially the spherical aberration of the objective lens. Image deconvolution could correct for the image distortion by lens aberrations and restore the structure projection, the resolution of which is limited by the information limit of the microscope. Electron diffraction unrestricted by lens aberrations could overcome this resolution limit. Here we show a combination of electron diffraction and image deconvolution to reveal simultaneously the atomic columns of O and considerably heavier Sm at a very close distance (1.17 Å) in iron-based superconductor SmFeAsO0.85F0.15 using a conventional 200 kV electron microscope. The approach used here, starting from an image and an electron diffraction pattern, has an advantage for those radiation-sensitive samples. Besides, it can be applied to simultaneously imaging light and heavy atoms, even though they have a big difference in atomic number and a much smaller atomic distance than the microscope resolution. PMID:25635603

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

    International Nuclear Information System (INIS)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Stroppa, Daniel G., E-mail: dstroppa@lnls.br [Brazilian Synchrotron Light Laboratory, 13083-970 Campinas, SP (Brazil); Mechanical Engineering School, University of Campinas, 13083-860 Campinas, SP (Brazil); Righetto, Ricardo D. [Brazilian Synchrotron Light Laboratory, 13083-970 Campinas, SP (Brazil); School of Electrical and Computer Engineering, University of Campinas, 13083-852 Campinas, SP (Brazil); Montoro, Luciano A. [Brazilian Synchrotron Light Laboratory, 13083-970 Campinas, SP (Brazil); Ramirez, Antonio J. [Brazilian Synchrotron Light Laboratory, 13083-970 Campinas, SP (Brazil); Mechanical Engineering School, University of Campinas, 13083-860 Campinas, SP (Brazil)

    2011-07-15

    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: {yields} A software to support the HRTEM image simulation of nanocrystals in actual size. {yields} MEGACELL allows the construction of complex nanocrystals models for multislice image simulation. {yields} Some examples of improved nanocrystalline system characterization are presented, including the analysis of 3D morphology and growth behavior.

  11. SAED and HRTEM Investigation of Palygorskite

    Institute of Scientific and Technical Information of China (English)

    CHEN Tao; WANG Hejing; ZHANG Xiaoping; ZHENG Nan

    2008-01-01

    The microstructure of palygorskite from Longwang Mountain of Xuyu County, Jiangsu Province, was studied by energy dispersive X-ray analysis (EDX), selected-area electron diffraction (SAED) and high-resolution transmission electron microscopy (HRTEM). The average composition of the palygorskite studied is (Si7.38Al0.62) (Al0.96Fe3+0.62Mg2.86□0.56)Ca0.03K0.06O20(OH)2(OH2)4, which is rich in Mg. Several SAED patterns from a single crystal of palygorskite were obtained with different zone axes. The polymorphs (monoclinic and orthorhombic) are unequivocally distinguished by distant interplanar angles, even though they possess similar sets of d-values. High-resolution images of three principal zones ([010], [100] and [110]) were obtained. The lattice fringes on HRTEM images along [010] have spacings of 0.319 nm. These fringes are interpreted as periodic alterations of two tetrahedral (T) sheets and one octahedral (O) sheet (-TT-O-TT-O-). We have directly observed trioctahedral and dioctahedral individual palygorskite particles along [100]. They are all presented as dark lines along [001], but the width of dark lines corresponding to trioctahedral crystals (0.913 nm) is twice that of the dioctahedral ones (0.456 nm). This is because the trans-sites are occupied by cations in trioctahedral palygorskite. The width of dark lines along [110] is 1.024 nm, a bit thinner than the theoretical spacing (1.044 nm). This is because water molecules quickly leave the structure upon the irradiation by the electron beam.

  12. 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.

  13. Rectification in substituted atomic wires: a theoretical insight.

    Science.gov (United States)

    Asai, Yoshihiro

    2012-04-25

    Recently, there have been discussions that the giant diode property found experimentally in diblock molecular junctions could be enhanced by the many-body electron correlation effect beyond the mean field theory. In addition, the effect of electron-phonon scattering on an electric current through the diode molecule, measured by inelastic tunneling spectroscopy (IETS), was found to be symmetric with respect to the voltage sign change even though the current is asymmetric. The reason for this behavior is a matter of speculation. In order to clarify whether or not this feature is limited to organic molecules in the off-resonant tunneling region, we discuss the current asymmetry effect on IETS in the resonant region. We introduced heterogeneous atoms into an atomic wire and found that IETS becomes asymmetric in this substituted atomic wire case. Our conclusion gives the other example of intrinsic differences between organic molecules and metallic wires. While the contribution of electron-phonon scattering to IETS is not affected by the current asymmetry in the former case, it is affected in the latter case. The importance of the contribution of the electron-hole excitation to phonon damping in bringing about the current asymmetry effect in IETS in the latter case is discussed. PMID:22466527

  14. Atomic scale insights into urea-peptide interactions in solution.

    Science.gov (United States)

    Steinke, Nicola; Gillams, Richard J; Pardo, Luis Carlos; Lorenz, Christian D; McLain, Sylvia E

    2016-02-01

    The mechanism by which proteins are denatured by urea is still not well understood, especially on the atomic scale where these interactions occur in vivo. In this study, the structure of the peptide GPG has been investigated in aqueous urea solutions in order to understand the combination of roles that both urea and water play in protein unfolding. Using a combination of neutron diffraction enhanced by isotopic substitution and computer simulations, it was found, in opposition with previous simulations studies, that urea is preferred over water around polar and charged portions of the peptides. Further, it appears that while urea directly replaces water around the nitrogen groups on GPG that urea and water occupy different positions around the peptide bond carbonyl groups. This suggests that urea may in fact weaken the peptide bond, disrupting the peptide backbone, thus ultimately causing denaturation. PMID:26764567

  15. 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...... acids into proteins. We also review insights into the function and pharmacology of voltage-gated ion channels that have emerged from unnatural amino acid mutagenesis approaches....

  16. HRTEM at half-Angstrom resolution: From OAM to TEAM

    Energy Technology Data Exchange (ETDEWEB)

    O' Keefe, Michael A.

    2003-02-17

    Transmission electron microscopy (TEM) at sub-Angstrom resolution is important for nanotechnology. Identifying atom positions requires appropriate resolution, the ability to separate distinct objects in images. With Cs corrected, the information limit of the TEM controls resolution. The OAM has demonstrated that a resolution of 0.78A is possible. The TEAM (transmission electron achromatic microscope) will be a TEM using hardware correction of Cs with a monochromator to improve its information limit beyond that of the OAM by improvement of the electron-beam energy spread. It is shown that A 300keV HRTEM TEAM does not require a Cc corrector to reach 0.5A as long as beam energy spread and objective-lens current ripple are lowered sufficiently. A lower-voltage TEAM will require stricter limits on objective-lens current ripple to reach the targeted 0.5A resolution. No improvement in HT ripple or noise is required to improve the information limit per se since the monochromator determines the energy spread in the beam. However, improved HT ripple and noise will improve the beam current statistics (number of electrons passing through the monochromator) by placing more of the electrons closer to the center of the energy-spread distribution

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

    International Nuclear Information System (INIS)

    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

  18. 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.

  19. Radiation damage during HRTEM studies in pure Al and Al alloys

    Energy Technology Data Exchange (ETDEWEB)

    Mingler, B.; H. Peter Karnthaler [Univ. of Vienna (Austria). Inst. of Materials Physics

    2006-07-15

    During transmission electron microscopy (TEM) investigations of Al alloys, defects caused by the electron irradiation can occur. Since the image contrast of these irradiation defects is similar to that of early stages of precipitates, care is needed to avoid confusion. In the present paper the formation and the coarsening of radiation damage defects were studied by in situ TEM in both, pure Al and Al alloys. High-resolution (HR)TEM images show on an atomic level that the radiation defects are extrinsic Frank loops (some converted into unfaulted prismatic loops); they are distributed homogeneously within the TEM foil but inhomogeneously on the four {l_brace}111{r_brace} planes. Applying HRTEM imaging conditions, the minimum electron energy causing defects is found to be as low as 110 keV using a [110] beam direction. The results for pure Al are very similar to those of the Al alloys. Therefore, during HRTEM studies (using accelerating voltages > 100 kV) the formation of radiation defects seems inevitable; they can be distinguished from the early stages of precipitates if they lie on different planes. (orig.)

  20. Radiation damage during HRTEM studies in pure Al and Al alloys

    International Nuclear Information System (INIS)

    During transmission electron microscopy (TEM) investigations of Al alloys, defects caused by the electron irradiation can occur. Since the image contrast of these irradiation defects is similar to that of early stages of precipitates, care is needed to avoid confusion. In the present paper the formation and the coarsening of radiation damage defects were studied by in situ TEM in both, pure Al and Al alloys. High-resolution (HR)TEM images show on an atomic level that the radiation defects are extrinsic Frank loops (some converted into unfaulted prismatic loops); they are distributed homogeneously within the TEM foil but inhomogeneously on the four {111} planes. Applying HRTEM imaging conditions, the minimum electron energy causing defects is found to be as low as 110 keV using a [110] beam direction. The results for pure Al are very similar to those of the Al alloys. Therefore, during HRTEM studies (using accelerating voltages > 100 kV) the formation of radiation defects seems inevitable; they can be distinguished from the early stages of precipitates if they lie on different planes. (orig.)

  1. 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.

  2. A HRTEM and XRD Study of the Potassium Hexatitanate Nanowires

    Institute of Scientific and Technical Information of China (English)

    Bingshe XU; Peide HAN; Jian LIANG; Yuan YU; Huiqiang BAO; Xuguang LIU

    2004-01-01

    The structure of potassium hexatitanate (K2Ti6O13) nanowires has been investigated using both the Rietveld powder diffraction profile fitting technique and high resolution transmission electron microscopy (HRTEM) image simulations.From the Rietveld analysis it was shown that the nanowires had a monoclinic structure of the space group C2/M and the lattice parameters were a=1.5582 nm, b=0.382 nm, c=0.9112 nm. HRTEM conclusions agree with refinement results obtained from experimental XRD data. The good agreement between the experimental and simulated images confirms that the nanowires is indeed K2Ti6O13 nanowire. The growth axes of nanowires were mainly along the [010] direction.

  3. Acetate- and thiol-capped monodisperse ruthenium nanoparticles: XPS, XAS, and HRTEM studies.

    Science.gov (United States)

    Chakroune, Nassira; Viau, Guillaume; Ammar, Souad; Poul, Laurence; Veautier, Delphine; Chehimi, Mohamed M; Mangeney, Claire; Villain, Françoise; Fiévet, Fernand

    2005-07-19

    Monodisperse ruthenium nanoparticles were prepared by reduction of RuCl3 in 1,2-propanediol. The mean particle size was controlled by appropriate choice of the reduction temperature and the acetate ion concentration. Colloidal solutions in toluene were obtained by coating the metal particles with dodecanethiol. High-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and X-ray absorption spectroscopy (XANES and EXAFS for the Ru K-absorption edge) were performed on particles of two different diameters, 2 and 4 nm, and in different environments, polyol/acetate or thiol. For particles stored in polyol/acetate XPS studies revealed superficial oxidation limited to one monolayer and a surface coating containing mostly acetate ions. Analysis of the EXAFS spectra showed both oxygen and ruthenium atoms around the ruthenium atoms with a Ru-Ru coordination number N smaller than the bulk value, as expected for fine particles. In the case of 2 nm acetate-capped particles N is consistent with particles made up of a metallic core and an oxidized monolayer. For 2 nm thiol-coated particles, a Ru-S bond was evidenced by XPS and XAS. For the 4 nm particles XANES and XPS studies showed that most of the ruthenium atoms are in the zerovalent state. Nevertheless, in both cases, when capped with thiol, the Ru-Ru coordination number inferred from EXAFS is much smaller than for particles of the same size stored in polyol. This is attributed to a structural disorganization of the particles by thiol chemisorption. HRTEM studies confirm the marked dependence of the structural properties of the ruthenium particles on their chemical environment; they show the acetate-coated particles to be single crystals, whereas the thiol-coated particles appear to be polycrystalline. PMID:16008388

  4. 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

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

    Energy Technology Data Exchange (ETDEWEB)

    Gutierrez-Gonzalez, C.F. [Centro de Investigacion en Nanomateriales y Nanotecnologia (CINN), Consejo Superior de Investigaciones Cientificas - CSIC - Universidad de Oviedo - UO - Principado de Asturias - PA, Parque Tecnologico de Asturias, 33428 Llanera (Spain); Agouram, S. [Department of Applied Physics and Electromagnetism, Universitat de Valencia, 46100 Burjassot (Spain); Torrecillas, R. [Centro de Investigacion en Nanomateriales y Nanotecnologia (CINN), Consejo Superior de Investigaciones Cientificas - CSIC - Universidad de Oviedo -UO - Principado de Asturias- PA, Parque Tecnologico de Asturias, 33428 Llanera (Spain); Moya, J.S. [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas (ICMM-CSIC), Cantoblanco, 28049 Madrid (Spain); Lopez-Esteban, S., E-mail: s.lopez@cinn.es [Centro de Investigacion en Nanomateriales y Nanotecnologia (CINN), Consejo Superior de Investigaciones Cientificas - CSIC - Universidad de Oviedo - UO - Principado de Asturias - PA, Parque Tecnologico de Asturias, 33428 Llanera (Spain)

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer A cryogenic route has been used to obtain ceramic/metal nanostructured powders. Black-Right-Pointing-Pointer The powders present good homogeneity and dispersion of metal. Black-Right-Pointing-Pointer The metal nanoparticle size distributions are centred in 17-35 nm. Black-Right-Pointing-Pointer Both phases, ceramic and metal, present a high degree of crystallinity. Black-Right-Pointing-Pointer 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)

    Both the mass density (1.37 kgm/m3) and sp2+sp3 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, C60, 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. Ceramic/metal nanocomposites by lyophilization: Processing and HRTEM study

    International Nuclear Information System (INIS)

    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.

  8. Quantitative analysis of microstructure of carbon materials by HRTEM

    Institute of Scientific and Technical Information of China (English)

    YANG Jun-he; CHENG Shu-hui; WANG Xia; ZHANG Zhuo; LIU Xiao-rong; TANG Guo-hua

    2006-01-01

    The main object of the present research is to make a quantitative evaluation on the microstructure of carbon materials in terms of microcrystal. The digitized images acquired from finely pulverized carbon materials under HRTEM at a high magnification were processed by the image processing software so as to extract the fringes of (002) lattice of graphite crystal from the background image,and an FFT-IFFT filtering operation was performed followed by processes as binarization for the image and skeletonization for the fringes. A set of geometrical parameters including position,length and orientation was set up for every lattice fringe by calculating the binarized image. Then,the above obtained fringe parameters were put into an algorithm,which was especially developed for such fringe images so as to find fringes that could be regarded as those belonged to one single graphite microcrystal. The fringe was subjected sequentially to comparing procedures with every other fringe on aspects as parallelism,relative position and spacing,and the above comparisons were repeated till the last fringe. Eventually,the microcrystal size,its stacking number,and the distribution of the microcrystal in the whole sample,as well as other related structure information of such microcrystal in carbon materials were statistically calculated. Such microstructure information at nanometer level may contribute greatly to the interpretation of the properties of carbon materials and a better correlation with the same macrostructure.

  9. X-ray diffraction @ elettra synchrotron: atomic insight of your biomedical target

    OpenAIRE

    Bais, Giorgio; et al, ...

    2014-01-01

    Crystallography is an invaluable tool to understand atomic structure. The knowledge at atomic scale of small and large molecules is crucial for many biomedical and biotechnological applications, ranging from drug design and optimization to enzyme functional studies and engineering. The physical properties of the solid state seen in crystals and powders of both drugs and pharmaceutical excipients are of interest because the nature of the crystalline form of a drug substance, due to...

  10. Atoms

    Institute of Scientific and Technical Information of China (English)

    刘洪毓

    2007-01-01

    Atoms(原子)are all around us.They are something like the bricks (砖块)of which everything is made. The size of an atom is very,very small.In just one grain of salt are held millions of atoms. Atoms are very important.The way one object acts depends on what

  11. Atoms

    International Nuclear Information System (INIS)

    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. Orbital origin of the electrical conduction in ferromagnetic atomic-size contacts: Insights from shot noise measurements and theoretical simulations

    Science.gov (United States)

    Vardimon, R.; Matt, M.; Nielaba, P.; Cuevas, J. C.; Tal, O.

    2016-02-01

    With the goal of elucidating the nature of spin-dependent electronic transport in ferromagnetic atomic contacts, we present here a combined experimental and theoretical study of the conductance and shot noise of metallic atomic contacts made of the 3 d ferromagnetic materials Fe, Co, and Ni. For comparison, we also present the corresponding results for the noble metal Cu. Conductance and shot noise measurements, performed using a low-temperature break-junction setup, show that in these ferromagnetic nanowires, (i) there is no conductance quantization of any kind, (ii) transport is dominated by several partially open conduction channels, even in the case of single-atom contacts, and (iii) the Fano factor of large contacts saturates to values that clearly differ from those of monovalent (nonmagnetic) metals. We rationalize these observations with the help of a theoretical approach that combines molecular dynamics simulations to describe the junction formation with nonequilibrium Green's function techniques to compute the transport properties within the Landauer-Büttiker framework. Our theoretical approach successfully reproduces all the basic experimental results and it shows that all the observations can be traced back to the fact that the d bands of the minority-spin electrons play a fundamental role in the transport through ferromagnetic atomic-size contacts. These d bands give rise to partially open conduction channels for any contact size, which in turn lead naturally to the different observations described above. Thus, the transport picture for these nanoscale ferromagnetic wires that emerges from the ensemble of our results is clearly at variance with the well established conduction mechanism that governs the transport in macroscopic ferromagnetic wires, where the d bands are responsible for the magnetism but do not take part in the charge flow. These insights provide a fundamental framework for ferromagnetic-based spintronics at the nanoscale.

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

    International Nuclear Information System (INIS)

    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, He2+-He, and Arq+-He (q=15-18)

  14. 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.

  15. Molecular self-assembly on two-dimensional atomic crystals: insights from molecular dynamics simulations.

    Science.gov (United States)

    Zhao, Yinghe; Wu, Qisheng; Chen, Qian; Wang, Jinlan

    2015-11-19

    van der Waals (vdW) epitaxy of ultrathin organic films on two-dimensional (2D) atomic crystals has become a sovereign area because of their unique advantages in organic electronic devices. However, the dynamic mechanism of the self-assembly remains elusive. Here, we visualize the nanoscale self-assembly of organic molecules on graphene and boron nitride monolayer from a disordered state to a 2D lattice via molecular dynamics simulation for the first time. It is revealed that the assembly toward 2D ordered structures is essentially the minimization of the molecule-molecule interaction, that is, the vdW interaction in nonpolar systems and the vdW and Coulomb interactions in polar systems that are the decisive factors for the formation of the 2D ordering. The role of the substrate is mainly governing the array orientation of the adsorbates. The mechanisms unveiled here are generally applicable to a broad class of organic thin films via vdW epitaxy. PMID:26523464

  16. 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

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

    International Nuclear Information System (INIS)

    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

  18. A Tool for Local Thickness Determination and Grain Boundary Characterization by CTEM and HRTEM Techniques.

    Science.gov (United States)

    Kiss, Ákos K; Rauch, Edgar F; Pécz, Béla; Szívós, János; Lábár, János L

    2015-04-01

    A new approach for measurement of local thickness and characterization of grain boundaries is presented. The method is embodied in a software tool that helps to find and set sample orientations useful for high-resolution transmission electron microscopic (HRTEM) examination of grain boundaries in polycrystalline thin films. The novelty is the simultaneous treatment of the two neighboring grains and orienting both grains and the boundary plane simultaneously. The same metric matrix-based formalism is used for all crystal systems. Input into the software tool includes orientation data for the grains in question, which is determined automatically for a large number of grains by the commercial ASTAR program. Grain boundaries suitable for HRTEM examination are automatically identified by our software tool. Individual boundaries are selected manually for detailed HRTEM examination from the automatically identified set. Goniometer settings needed to observe the selected boundary in HRTEM are advised by the software. Operation is demonstrated on examples from cubic and hexagonal crystal systems. PMID:25801740

  19. Optimum HRTEM image contrast at 20 kV and 80 kV—Exemplified by graphene

    International Nuclear Information System (INIS)

    The dependence of high-resolution transmission electron microscopy (HRTEM) image contrast of graphene on the adjustable parameters of an aberration-corrected microscope operated at 80 and 20 kV has been calculated and, for 80 kV, compared with measurements. We used density functional theory to determine the projected atom potential and obtained the image intensity by averaging over the energy distribution of the imaging electrons, as derived from the electron energy loss spectroscopy measurements. Optimum image contrast has been determined as a function of energy spread of the imaging electrons and chromatic aberration coefficient, showing that significant improvement of contrast can be achieved at 80 kV with the help of a monochromator, however at 20 kV only with chromatic aberration correction and bright atom contrast conditions. -- Highlights: ► Calculation of image contrast of graphene based on a combination of theory (POA) and experiment (EELS). ► At 80 kV, image contrast can be increased effectively by a monochromator. ► At 20 kV, enhanced image contrast requires chromatic aberration correction.

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

    Science.gov (United States)

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

    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.

  1. HRTEM investigations of structure and composition of polar Pd/ZnO heterophase interfaces

    OpenAIRE

    Saito, Mitsuhiro

    2005-01-01

    The present work is a fundamental, quantitative and systematic study of the structure and bonding of Pd/{0001}ZnO interfaces. The interface was studied experimentally via high-resolution transmission electron microscopy (HRTEM). These studies were completed by semi-quantitative first principle calculations and crystal truncation rod measurements. The ZnO substrate surfaces were prepared under well-defined oxygen atmospheres and in ultra-high vacuum (UHV). Flat, stepped, contamination free,...

  2. Using coherent illumination to extend HRTEM resolution: Why we need a FEG-TEM for HREM

    Energy Technology Data Exchange (ETDEWEB)

    O`Keefe, M.A.

    1992-11-01

    Resolution of a high-resolution transmission electron microscope (HRTEM) has traditionally been defined in terms of its Scherzer resolution limit at optimum defocus. However, even beyond the Scherzer limit, spatial frequencies can be transferred from the specimen to the image, out to the so-called information limit of the electron microscope. The information limit of the HRTEM is determined by the degree of energy spread in the electron beam used to illuminate the sample. Since a HRTEM equipped with a field-emission gun (FEG) will produce an electron beam of high coherence with little energy spread, it can achieve an improved information-limit, and can thus be used to produce through-focus series of images containing information well beyond its nominal (Scherzer) resolution limit. Suitable computer processing of such series of images can produce composite images at resolutions approaching the microscope information limit. For such a FEG-TEM, combined with suitable computer image processing, resolution can approach 1{Angstrom}. 12 refs., 9 figs.

  3. Using coherent illumination to extend HRTEM resolution: Why we need a FEG-TEM for HREM

    Energy Technology Data Exchange (ETDEWEB)

    O' Keefe, M.A.

    1992-11-01

    Resolution of a high-resolution transmission electron microscope (HRTEM) has traditionally been defined in terms of its Scherzer resolution limit at optimum defocus. However, even beyond the Scherzer limit, spatial frequencies can be transferred from the specimen to the image, out to the so-called information limit of the electron microscope. The information limit of the HRTEM is determined by the degree of energy spread in the electron beam used to illuminate the sample. Since a HRTEM equipped with a field-emission gun (FEG) will produce an electron beam of high coherence with little energy spread, it can achieve an improved information-limit, and can thus be used to produce through-focus series of images containing information well beyond its nominal (Scherzer) resolution limit. Suitable computer processing of such series of images can produce composite images at resolutions approaching the microscope information limit. For such a FEG-TEM, combined with suitable computer image processing, resolution can approach 1[Angstrom]. 12 refs., 9 figs.

  4. 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

    2016-05-01

    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. PMID:27070292

  5. A Quantum Similarity Study of Atomic Density Functions: Insights from Information Theory and the Role of Relativistic Effects

    CERN Document Server

    Borgoo, A; Indelicato, P; De Proft, F; Geerlings, P; Indelicato, Paul

    2007-01-01

    A novel quantum similarity measure (QSM) is constructed based on concepts from information theory. In an application of QSM to atoms, the new QSM and its corresponding quantum similarity index (QSI) are evaluated throughout the periodic table, using the atomic electron densities and shape functions calculated in the Hartree-Fock approximation. The periodicity of Mendeleev's table is regained for the first time through the evaluation of a QSM. Evaluation of the information theory based QSI demonstrates, however, that the patterns of periodicity are lost due to the renormalization of the QSM, yielding chemically less appealing results for the QSI. A comparison of the information content of a given atom on top of a group with the information content of the elements in the subsequent rows reveals another periodicity pattern. Relativistic effects on the electronic density functions of atoms are investigated. Their importance is quantified in a QSI study by comparing for each atom, the density functions evaluated i...

  6. HRTEM investigation of phase stability in alumina–zirconia multilayer thin films

    Indian Academy of Sciences (India)

    Chanchal Ghosh; Divakar Ramachandran; G Balakrishnan; P Kuppusami; E Mohandas

    2015-04-01

    Phase stability of nanostructured thin films can be significantly different from the stability of the same materials in bulk form because of the increased contribution from surface and interface effects. Zirconia (ZrO2), stabilized in tetragonal and cubic phases, is a technologically important material and is used for most high temperature applications. In literature, zirconia can be found to be stabilized in its high temperature phases down to room temperature via two routes, doping with divalent or trivalent cations and crystallite size controls. Apart from these, in the alumina/zirconia thin-film multilayer system, a constraining effect on the zirconia layers provides another route to stabilization of the tetragonal zirconia phase at room temperature. However, in such nanostructured geometries, at high temperatures, the small diffusion lengths involved can influence the phase stability. The present work deals with the high-resolution transmission electron microscope (HRTEM) studies of pulsed laser ablated alumina–zirconia thin-film multilayers in the as deposited state and annealed up to 1473 K at 2 × 10−5 mbar. Conventional techniques such as X-ray diffraction lack the ability to detect localized phase changes at nanometre length scales and also for the low volume fraction of newly formed phases. Cross-sectional HRTEM techniques have been successful in detecting and characterizing these interactions.

  7. Crystal structure of post-perovskite-type CaIrO3 reinvestigated: new insights into atomic thermal vibration behaviors

    Directory of Open Access Journals (Sweden)

    Akihiko Nakatsuka

    2015-09-01

    Full Text Available Single crystals of the title compound, the post-perovskite-type CaIrO3 [calcium iridium(IV trioxide], have been grown from a CaCl2 flux at atmospheric pressure. The crystal structure consists of an alternate stacking of IrO6 octahedral layers and CaO8 hendecahedral layers along [010]. Chains formed by edge-sharing of IrO6 octahedra (point-group symmetry 2/m.. run along [100] and are interconnected along [001] by sharing apical O atoms to build up the IrO6 octahedral layers. Chains formed by face-sharing of CaO8 hendecahedra (point-group symmetry m2m run along [100] and are interconnected along [001] by edge-sharing to build up the CaO8 hendecahedral layers. The IrO6 octahedral layers and CaO8 hendecahedral layers are interconnected by sharing edges. The present structure refinement using a high-power X-ray source confirms the atomic positions determined by Hirai et al. (2009 [Z. Kristallogr. 224, 345–350], who had revised our previous report [Sugahara et al. (2008. Am. Mineral. 93, 1148–1152]. However, the displacement ellipsoids of the Ir and Ca atoms based on the present refinement can be approximated as uniaxial ellipsoids elongating along [100], unlike those reported by Hirai et al. (2009. This suggests that the thermal vibrations of the Ir and Ca atoms are mutually suppressed towards the Ir...Ca direction across the shared edge because of the dominant repulsion between the two atoms.

  8. Crystal structure of post-perovskite-type CaIrO3 reinvestigated: new insights into atomic thermal vibration behaviors.

    Science.gov (United States)

    Nakatsuka, Akihiko; Sugiyama, Kazumasa; Yoneda, Akira; Fujiwara, Keiko; Yoshiasa, Akira

    2015-09-01

    Single crystals of the title compound, the post-perovskite-type CaIrO3 [calcium iridium(IV) trioxide], have been grown from a CaCl2 flux at atmospheric pressure. The crystal structure consists of an alternate stacking of IrO6 octa-hedral layers and CaO8 hendeca-hedral layers along [010]. Chains formed by edge-sharing of IrO6 octa-hedra (point-group symmetry 2/m..) run along [100] and are inter-connected along [001] by sharing apical O atoms to build up the IrO6 octa-hedral layers. Chains formed by face-sharing of CaO8 hendeca-hedra (point-group symmetry m2m) run along [100] and are inter-connected along [001] by edge-sharing to build up the CaO8 hendeca-hedral layers. The IrO6 octa-hedral layers and CaO8 hendeca-hedral layers are inter-connected by sharing edges. The present structure refinement using a high-power X-ray source confirms the atomic positions determined by Hirai et al. (2009 ▸) [Z. Kristallogr. 224, 345-350], who had revised our previous report [Sugahara et al. (2008 ▸). Am. Mineral. 93, 1148-1152]. However, the displacement ellipsoids of the Ir and Ca atoms based on the present refinement can be approximated as uniaxial ellipsoids elongating along [100], unlike those reported by Hirai et al. (2009 ▸). This suggests that the thermal vibrations of the Ir and Ca atoms are mutually suppressed towards the Ir⋯Ca direction across the shared edge because of the dominant repulsion between the two atoms. PMID:26396860

  9. In situ dynamic HR-TEM and EELS study on phase transitions of Ge2Sb2Te5 chalcogenides

    International Nuclear Information System (INIS)

    The phase transition phenomena of Ge2Sb2Te5 chalcogenides were investigated by in situ dynamic high-resolution transmission electron microscopy (HR-TEM) and electron energy loss spectroscopy (EELS). A 300 kV field emission TEM and a 1250 kV high voltage TEM were employed for the in situ heating experiments from 20 to 500 deg. C for undoped and 3 wt% nitrogen-doped Ge2Sb2Te5 thin films deposited by DC sputtering. Crystallization of amorphous Ge2Sb2Te5 to its cubic structure phase started at 130 deg. C and then rapid crystal growth developed from cubic to hexagonal phase in the range of 130-350 deg. C; finally, the hexagonal crystals started to melt at 500 deg. C. For nitrogen-doped Ge2Sb2Te5, its crystallization from amorphous film occurred at higher temperature of ca. 200 deg. C, and the cubic and hexagonal phases were usually formed simultaneously without significant growth of crystals at further heating to 400 deg. C. EELS measurements showed that the electronic structures of Ge, Sb and Te stayed almost the same regardless of the amorphous, FCC and hexagonal phases. The nitrogen doped in Ge2Sb2Te5 was confirmed to exist as a nitride. Also, the doped nitrogen distributed homogeneously in both amorphous and crystalline phases. Localization of doped nitrogen was not found in the grain boundary of crystallized phases. The dynamic process of phase transition was enhanced by high-energy electron irradiation. Peeling of atomic layers in nitrogen-doped Ge2Sb2Te5 film was detected during heating assisted with electron beam irradiation

  10. Quasi-atomic model of bacteriophage t7 procapsid shell: insights into the structure and evolution of a basic fold.

    Science.gov (United States)

    Agirrezabala, Xabier; Velázquez-Muriel, Javier A; Gómez-Puertas, Paulino; Scheres, Sjors H W; Carazo, José M; Carrascosa, José L

    2007-04-01

    The existence of similar folds among major structural subunits of viral capsids has shown unexpected evolutionary relationships suggesting common origins irrespective of the capsids' host life domain. Tailed bacteriophages are emerging as one such family, and we have studied the possible existence of the HK97-like fold in bacteriophage T7. The procapsid structure at approximately 10 A resolution was used to obtain a quasi-atomic model by fitting a homology model of the T7 capsid protein gp10 that was based on the atomic structure of the HK97 capsid protein. A number of fold similarities, such as the fitting of domains A and P into the L-shaped procapsid subunit, are evident between both viral systems. A different feature is related to the presence of the amino-terminal domain of gp10 found at the inner surface of the capsid that might play an important role in the interaction of capsid and scaffolding proteins. PMID:17437718

  11. Computational insights into the effect of carbon structures at the atomic level for non-aqueous sodium-oxygen batteries

    Science.gov (United States)

    Jiang, H. R.; Wu, M. C.; Zhou, X. L.; Yan, X. H.; Zhao, T. S.

    2016-09-01

    Carbon materials have been widely used to form air cathodes for non-aqueous sodium-oxygen (Nasbnd O2) batteries due to their large specific surface area, high conductivity and low cost. However, the effect of carbon structures at the atomic level remains poorly understood. In this work, a first-principles study is conducted to investigate how representative carbon structures, including graphite (0001) surface, point defects and fractured edge, influence the discharge and charge processes of non-aqueous Nasbnd O2 batteries. It is found that the single vacancy (SV) defect has the largest adsorption energy (5.81 eV) to NaO2 molecule among the structures studied, even larger than that of the NaO2 molecule on NaO2 crystal (2.81 eV). Such high adsorption energy is attributed to two factors: the dangling atoms in SV defects decrease the distance from NaO2 molecules, and the attachment through oxygen atoms increases the electrons transfer. The findings suggest that SV defects can act as the nucleation sites for NaO2 in the discharge process, and increasing the number of SV defects can facilitate the uniform formation of small-sized particles. The uniformly distributed discharge products lower the possibility for pore clogging, leading to an increased discharge capacity and improved cyclability for non-aqueous Nasbnd O2 batteries.

  12. Abnormal periodicities due to astigmatism in HRTEM images of orthorhombic zirconia

    International Nuclear Information System (INIS)

    Full text: Apparently 'anomalous' images associated with diffracted beams that are both kinematically and dynamically forbidden are well known at close to zone-axis oriented crystals. These images have been explained as being due to the effects of small beam tilts and/or crystal tilts away from the zone axis, or possibly arising from changes in alignment on switching between image and SAD modes. Here we show using both experimental and simulated images that residual astigmatism can lead to abnormal periodicities in HRTEM images of orthorhombic ZrO2. In this case, the appearance of the 'anomalous' lattice fringe spacings is due to changes in diffracted beam amplitudes or phases of non-forbidden reflections due to small amounts of astigmatism resulting from specimen charging effects. Copyright (2002) Australian Society for Electron Microscopy Inc

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

    International Nuclear Information System (INIS)

    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

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

    International Nuclear Information System (INIS)

    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.

  15. Crystal structure of post-perovskite-type CaIrO3 reinvestigated: new insights into atomic thermal vibration behaviors

    OpenAIRE

    Akihiko Nakatsuka; Kazumasa Sugiyama; Akira Yoneda; Keiko Fujiwara; Akira Yoshiasa

    2015-01-01

    Single crystals of the title compound, the post-perovskite-type CaIrO3 [calcium iridium(IV) trioxide], have been grown from a CaCl2 flux at atmospheric pressure. The crystal structure consists of an alternate stacking of IrO6 octahedral layers and CaO8 hendecahedral layers along [010]. Chains formed by edge-sharing of IrO6 octahedra (point-group symmetry 2/m..) run along [100] and are interconnected along [001] by sharing apical O atoms to build up the IrO6 octahedral layers. Chains formed by...

  16. Nanomechanics of silicon surfaces with atomic force microscopy: An insight to the first stages of plastic deformation

    Science.gov (United States)

    Garcia-Manyes, Sergi; Güell, Aleix G.; Gorostiza, Pau; Sanz, Fausto

    2005-09-01

    The use of stiff cantilevers with diamond tips allows us to perform nanoindentations on hard covalent materials such as silicon with atomic force microscopy. Thanks to the high sensitivity in the force measurements together with the high resolution upon imaging the surface, we can study nanomechanical properties. At this scale, the surface deforms, following a simple non-Hertzian spring model. The plastic onset can be assessed from a discontinuity in the force-distance curves. Hardness measurements with penetration depths as small as 1nm yield H =˜25GPa, thus showing a drastic increase with penetration depths below 5nm.

  17. Structural insights of non-canonical U•U pair and Hoogsteen interaction probed with Se atom

    OpenAIRE

    Sheng, Jia; Gan, Jianhua; Soares, Alexei S.; Salon, Jozef; Huang, Zhen

    2013-01-01

    Unlike DNA, in addition to the 2′-OH group, uracil nucleobase and its modifications play essential roles in structure and function diversities of non-coding RNAs. Non-canonical U•U base pair is ubiquitous in non-coding RNAs, which are highly diversified. However, it is not completely clear how uracil plays the diversifing roles. To investigate and compare the uracil in U-A and U•U base pairs, we have decided to probe them with a selenium atom by synthesizing the novel 4-Se-uridine (SeU) phosp...

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

    Energy Technology Data Exchange (ETDEWEB)

    Lehtinen, Ossi, E-mail: ossi.lehtinen@gmail.com [Central Facility for Electron Microscopy, Group of Electron Microscopy of Materials Science, University of Ulm, 89081 Ulm (Germany); Geiger, Dorin; Lee, Zhongbo [Central Facility for Electron Microscopy, Group of Electron Microscopy of Materials Science, University of Ulm, 89081 Ulm (Germany); Whitwick, Michael Brian; Chen, Ming-Wei; Kis, Andras [Electrical Engineering Institute, Ecole Polytechnique Federale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland); Kaiser, Ute [Central Facility for Electron Microscopy, Group of Electron Microscopy of Materials Science, University of Ulm, 89081 Ulm (Germany)

    2015-04-15

    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{sub 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.

  19. Atomic-Scale Insight into Tautomeric Recognition, Separation, and Interconversion of Guanine Molecular Networks on Au(111).

    Science.gov (United States)

    Zhang, Chi; Xie, Lei; Wang, Likun; Kong, Huihui; Tan, Qinggang; Xu, Wei

    2015-09-16

    Although tautomerization may directly affect the chemical or biological properties of molecules, real-space investigation on the tautomeric behaviors of organic molecules in a larger area of molecular networks has been scarcely reported. In this paper, we choose guanine (G) molecule as a model system. From the interplay of high-resolution scanning tunneling microscopy (STM) imaging and density functional theory (DFT) calculations, we have successfully achieved the tautomeric recognition, separation, and interconversion of G molecular networks (formed by two tautomeric forms G/9H and G/7H) with the aid of NaCl on the Au(111) surface in ultrahigh vacuum (UHV) conditions. Our results may serve as a prototypical system to provide important insights into tautomerization related issues, which should be intriguing to biochemistry, pharmaceutics, and other related fields. PMID:26322860

  20. Synthesis of Ag-Au Nanoparticles by Galvanic Replacement and Their Morphological Studies by HRTEM and Computational Modeling

    Directory of Open Access Journals (Sweden)

    Manuel Ramos

    2011-01-01

    Full Text Available Bimetallic nanoparticles are important because they possess catalytic and electronic properties with potential applications in medicine, electronics, and chemical industries. A galvanic replacement reaction synthesis has been used in this research to form bimetallic nanoparticles. The complete description of the synthesis consists of using the chemical reduction of metallic silver nitrite (AgNO3 and gold-III chloride hydrate (HAuCl salt precursors. The nanoparticles display round shapes, as revealed by high-resolution transmission electron microscope (HRTEM. In order to better understand the colloidal structure, it was necessary to employ computational models which involved the simulations of HRTEM images.

  1. Crystal structure of post-perovskite-type CaIrO3 reinvestigated: new insights into atomic thermal vibration behaviors

    OpenAIRE

    Nakatsuka, Akihiko; Sugiyama, Kazumasa; Yoneda, Akira; Fujiwara, Keiko; Yoshiasa, Akira

    2015-01-01

    Single crystals of the title compound, the post-perovskite-type CaIrO3 [calcium iridium(IV) trioxide], have been grown from a CaCl2 flux at atmospheric pressure. The crystal structure consists of an alternate stacking of IrO6 octa­hedral layers and CaO8 hendeca­hedral layers along [010]. Chains formed by edge-sharing of IrO6 octa­hedra (point-group symmetry 2/m..) run along [100] and are inter­connected along [001] by sharing apical O atoms to build up the IrO6 octa­hedral layers. Chains form...

  2. The mechanism of chemisorption of hydrogen atom on graphene: Insights from the reaction force and reaction electronic flux

    International Nuclear Information System (INIS)

    At the PBE-D3/cc-pVDZ level of theory, the hydrogen chemisorption on graphene was analyzed using the reaction force and reaction electronic flux (REF) theories in combination with electron population analysis. It was found that chemisorption energy barrier is mainly dominated by structural work (∼73%) associated to the substrate reconstruction whereas the electronic work is the greatest contribution of the reverse energy barrier (∼67%) in the desorption process. Moreover, REF shows that hydrogen chemisorption is driven by charge transfer processes through four electronic events taking place as H approaches the adsorbent surface: (a) intramolecular charge transfer in the adsorbent surface; (b) surface reconstruction; (c) substrate magnetization and adsorbent carbon atom develops a sp3 hybridization to form the σC-H bond; and (d) spontaneous intermolecular charge transfer to reach the final chemisorbed state

  3. Atomically Precise Prediction of 2D Self-Assembly of Weakly Bonded Nanostructures: STM Insight into Concentration-Dependent Architectures.

    Science.gov (United States)

    El Garah, Mohamed; Dianat, Arezoo; Cadeddu, Andrea; Gutierrez, Rafael; Cecchini, Marco; Cook, Timothy R; Ciesielski, Artur; Stang, Peter J; Cuniberti, Gianaurelio; Samorì, Paolo

    2016-01-20

    A joint experimental and computational study is reported on the concentration-dependant self-assembly of a flat C3 -symmetric molecule on a graphite surface. As a model system a tripodal molecule, 1,3,5-tris(pyridin-3-ylethynyl)benzene, has been chosen, which can adopt either C3h or Cs symmetry when planar, as a result of pyridyl rotation along the alkynyl spacers. Density functional theory (DFT) simulations of 2D nanopatterns with different surface coverage reveal that the molecule can generate different types of self-assembled motifs. The stability of fourteen 2D patterns and the influence of concentration are analyzed. It is found that ordered, densely packed monolayers and 2D porous networks are obtained at high and low concentrations, respectively. A concentration-dependent scanning tunneling microscopy (STM) investigation of this molecular self-assembly system at a solution/graphite interface reveals four supramolecular motifs, which are in perfect agreement with those predicted by simulations. Therefore, this DFT method represents a key step forward toward the atomically precise prediction of molecular self-assembly on surfaces and at interfaces. PMID:26596683

  4. Many-particle fragmentation processes in atomic and molecular physics. New insight into the world of correlation

    International Nuclear Information System (INIS)

    Full text: 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 multifragment 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 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. The principle of the new reaction microscope (synonym: COLTRIMS) will be presented. If imaging detectors based on fast delay-line position read-out are used multi-hit detection is possible. Even two particles hitting the detector at the 'same' instant (Δt < 1 ns) can simultaneously be detected. The number of detected multi-hits is practically only limited by the electronics needed to store in event mode all information. Several examples for COLTRIMS data will be shown: double excitation and ionization of He as well as complete differential data in momentum space for many particle fragmentation of molecules by ions and photons. The obtained information on e-e correlation is discussed

  5. Aberration measurement in HRTEM: Implementation and diagnostic use of numerical procedures for the highly precise recognition of diffractogram patterns

    International Nuclear Information System (INIS)

    The precise characterisation of the instrumental imaging properties in the form of aberration parameters constitutes an almost universal necessity in quantitative HRTEM, and is underlying most hardware and software techniques established in this field. We focus in this paper on the numerical analysis of individual diffractograms as a first preparatory step for further publications on HRTEM aberration measurement. The extraction of the defocus and the 2-fold astigmatism from a diffractogram is a classical pattern recognition problem, which we believe to have solved in a near-optimum way concerning precision, speed, and robustness. The newly gained measurement precision allows us to resolve fluctuations of the defocus and the 2-fold astigmatism and to assess thereby the optical stability of electron microscopes. Quantitative stability criteria are elaborated, which may serve as helpful guidelines for daily work as well as for microscope acceptance tests. -- Research Highlights: → Algorithms for the highly precise diffractogram analysis in HRTEM are introduced. → AMADEUS procedure measures defocus and astigmatism with a few Angstrom precision. → Aberration measurement meets the precision requirements of 0.5 A microscopy. → Quantitative criteria for the optical stability of HRTEMs are introduced.

  6. Unexpected periodicities in HRTEM images of orthorhombic zirconia due to astigmatism

    International Nuclear Information System (INIS)

    It is known that kinematically forbidden reflections caused by glide or screw symmetry elements remain forbidden dynamically under certain illumination conditions (The Gjonnes-Moodie extinction rules). These forbidden reflections can appear and contribute to images under conditions where crystal and/or beam tilt alignments are non-axial. Images with unexpected lattice periodicities due to beam tilt and/or crystal tilt have been refereed to as anomalous images and such images have been observed in various crystal structures. The situation in regard to thin crystals of rutile-like structures has been clarified where, by using CBED combined with HRTEM images at a range of crystal thicknesses, it was shown that rutile does exhibit the accepted space group (P42/mnm). In this paper we show that residual astigmatism can also lead to anomalous images similar to those caused by beam tilt and/or crystal tilt, but where the images are not due to the occurrence of forbidden reflections. Astigmatism has a severe effect on the high-resolution images of o-ZrO2 and for even a small amount of residual astigmatism, the images show marked changes in comparison to images calculated for perfect conditions. In fact, it was found that in most cases it was not possible to match simulated images with experimental images without considering the effect of astigmatism

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

    International Nuclear Information System (INIS)

    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.

  8. Atomic-scale insight into the interactions between hydroxyl radicals and DNA in solution using the ReaxFF reactive force field

    Science.gov (United States)

    Verlackt, C. C. W.; Neyts, E. C.; Jacob, T.; Fantauzzi, D.; Golkaram, M.; Shin, Y.-K.; van Duin, A. C. T.; Bogaerts, A.

    2015-10-01

    Cold atmospheric pressure plasmas have proven to provide an alternative treatment of cancer by targeting tumorous cells while leaving their healthy counterparts unharmed. However, the underlying mechanisms of the plasma-cell interactions are not yet fully understood. Reactive oxygen species, and in particular hydroxyl radicals (OH), are known to play a crucial role in plasma driven apoptosis of malignant cells. In this paper we investigate the interaction of OH radicals, as well as H2O2 molecules and HO2 radicals, with DNA by means of reactive molecular dynamics simulations using the ReaxFF force field. Our results provide atomic-scale insight into the dynamics of oxidative stress on DNA caused by the OH radicals, while H2O2 molecules appear not reactive within the considered time-scale. Among the observed processes are the formation of 8-OH-adduct radicals, forming the first stages towards the formation of 8-oxoGua and 8-oxoAde, H-abstraction reactions of the amines, and the partial opening of loose DNA ends in aqueous solution.

  9. TEM, HRTEM, electron holography and electron tomography studies of gamma' and gamma'' nanoparticles in Inconel 718 superalloy.

    Science.gov (United States)

    Dubiel, B; Kruk, A; Stepniowska, E; Cempura, G; Geiger, D; Formanek, P; Hernandez, J; Midgley, P; Czyrska-Filemonowicz, A

    2009-11-01

    The aim of the study was the identification of gamma' and gamma'' strengthening precipitates in a commercial nickel-base superalloy Inconel 718 (Ni-19Fe-18Cr-5Nb-3Mo-1Ti-0.5Al-0.04C, wt %) using TEM dark-field, HRTEM, electron holography and electron tomography imaging. To identify gamma' and gamma'' nanoparticles unambiguously, a systematic analysis of experimental and theoretical diffraction patterns were performed. Using HRTEM method it was possible to analyse small areas of precipitates appearance. Electron holography and electron tomography techniques show new possibilities of visualization of gamma' and gamma'' nanoparticles. The analysis by means of different complementary TEM methods showed that gamma'' particles exhibit a shape of thin plates, while gamma' phase precipitates are almost spherical. PMID:19903242

  10. HRTEM analysis on nanocrystalline BaTiO{sub 3} and PbTiO{sub 3}: size effects on ferroelectric phase transition temperature

    Energy Technology Data Exchange (ETDEWEB)

    Bursill, L.A.; Jiang, B.; Peng, J.L. [Melbourne Univ., Parkville, VIC (Australia). School of Physics; Zhong, W.L.; Zhang, P.L. [Shandong University (China). Physics Department

    1997-06-01

    High-Resolution Transmission Electron Microscopic studies of nanocrystaline particles of BaTiO{sub 3} and PbTiO{sub 3} are reported. There are characteristic differences observed for BaTiO{sub 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{sub 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{sub 3} prepared by the SG route remains tetragonal, albeit with decreasing c/a ratio, down to 25nm diameter. HRTEM observations of nanocrystalline PbTiO{sub 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.

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

    International Nuclear Information System (INIS)

    High-Resolution Transmission Electron Microscopic studies of nanocrystaline particles of BaTiO3 and PbTiO3 are reported. There are characteristic differences observed for BaTiO3 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 BaTiO3 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 PbTiO3 prepared by the SG route remains tetragonal, albeit with decreasing c/a ratio, down to 25nm diameter. HRTEM observations of nanocrystalline PbTiO3 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

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

    International Nuclear Information System (INIS)

    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

  13. Observation of different interfaces in silicon nitride by HRTEM. Influence of the microstructure on the creep properties

    Energy Technology Data Exchange (ETDEWEB)

    Bernard-Granger, G.; Cales, B. [Saint-Gobain Ceramiques Industrielles, Evreux (France). Centre de Recherches de Norton Desmarquest Fine Ceramics; Duclos, R.; Crampon, J. [Saint-Gobain Ceramiques Industrielles, Evreux (France). Centre de Recherches de Norton Desmarquest Fine Ceramics]|[LSPES, Univ. des Sciences et Technologies de Lille, Villeneuve d`Ascq (France)

    1997-12-31

    A new kind of silicon nitride ceramic has been prepared by mixing {alpha}-Si{sub 3}N{sub 4} and {alpha}-YSiAlON powders without sintering additives. Complete densification employing gas pressure sintering (GPS) has been achieved. Using high resolution transmission electronic microscopy (HRTEM) it is not possible to detect the presence of residual amorphous thin films at the different crystalline interfaces like conventionally reported for silicon nitride. This unique type of microstructure is probably at the origin of the very impressive creep performances measured for this ceramic.(orig.) 9 refs.

  14. Comparisons between adsorption and diffusion of alkali, alkaline earth metal atoms on silicene and those on silicane: Insight from first-principles calculations

    Science.gov (United States)

    Bo, Xu; Huan-Sheng, Lu; Bo, Liu; Gang, Liu; Mu-Sheng, Wu; Chuying, Ouyang

    2016-06-01

    The adsorption and diffusion behaviors of alkali and alkaline-earth metal atoms on silicane and silicene are both investigated by using a first-principles method within the frame of density functional theory. Silicane is staler against the metal adatoms than silicene. Hydrogenation makes the adsorption energies of various metal atoms considered in our calculations on silicane significantly lower than those on silicene. Similar diffusion energy barriers of alkali metal atoms on silicane and silicene could be observed. However, the diffusion energy barriers of alkali-earth metal atoms on silicane are essentially lower than those on silicene due to the small structural distortion and weak interaction between metal atoms and silicane substrate. Combining the adsorption energy with the diffusion energy barriers, it is found that the clustering would occur when depositing metal atoms on perfect hydrogenated silicene with relative high coverage. In order to avoid forming a metal cluster, we need to remove the hydrogen atoms from the silicane substrate to achieve the defective silicane. Our results are helpful for understanding the interaction between metal atoms and silicene-based two-dimensional materials. Project supported by the Natural Science Foundation of Jiangxi Province, China (Grant Nos. 20152ACB21014, 20151BAB202006, and 20142BAB212002) and the Fund from the Jiangxi Provincial Educational Committee, China (Grant No. GJJ14254). Bo Xu is also supported by the Oversea Returned Project from the Ministry of Education, China.

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

    International Nuclear Information System (INIS)

    Ferromagnetic FePd L10 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 L10 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. Characterization of collision cascade damage in Ca2La8(SiO4)6O2 by HRTEM

    International Nuclear Information System (INIS)

    Ca2La8(SiO4)6O2 thin crystals become amorphous under ion beam irradiation. The ion dose required for complete amorphization of the thin crystal (critical amorphization dose, Dc) increased with the increasing irradiation temperature and decreased with ion mass at elevated temperatures. Samples irradiated with 1-1.5 MeV Ar+, Kr+ and Xe+ ions to doses much lower than Dc, in the temperature range from 20 to 498 K were used for a detailed HRTEM study to better understand the amorphization process. The residual collision cascade damage after irradiation appeared as manometer scale amorphous domains. The images of these domains are extremely sensitive to the sample thickness. Small domains of cascade size were only found at the very thin edge of the sample. In thicker regions, amorphous domains appear after higher doses as the result of cascade overlap in projection. At higher temperatures, the observed amorphous domains are smaller indicating thermal recovery at the amorphous/crystalline interface. The amorphous domains are also larger in size after irradiation with ions of higher mass at a fixed ion dose. These results are consistent with the Dc-temperature curves determined by in situ TEM with the HVEM-Tandem Facility at Argonne National Laboratory. The width of the amorphous rim along the edge of the specimen grew with increasing ion dose suggesting that amorphization also proceeds from the sample surface. Images of the collision cascade damage were compared to the cascade sizes calculated with the TRIM code. Some digitally acquired HRTEM images of the cascade damage were processed to reveal more detailed information

  17. The determination of novel stuffed cristobalite superstructures by HRTEM and XRD

    International Nuclear Information System (INIS)

    Full text: High cristobalite is a framework silicate (SiO2) ideally described as cubic (Fd3m) in which every corner of each SiO4 tetrahedron is common with two tetrahedra in detail cristobalite chemistry is far more complex. The formation of cristobalites as clinker in hazardous waste incinerators are a serious operational problem. To better understand the formation of cristobalite, we have focused on the solid state chemistry of KAlSiO4 stuffed cristobalites. Starting with an oxide mixture of ideal stoichiometry, a suite of compounds were prepared by sintering over a range of various temperatures (900 - 1500 deg C) and times (1 - 7 d). The products were analysed by quantitative X ray fluorescence, powder X-ray diffraction and high resolution electron microscopy. The major results of the study were as follows: at higher temperatures volatilisation of K becomes significant, destabilising cristobalite compounds and ultimately leading to the crystallisation of leucite KAlSi2O6, while at lower temperatures (especially with longer firing times) superstructures were observed by X-ray and electron diffraction, the most abundant having the unit cell dimensions a=9.0383, b=15.6353, c= 8.5977 Angstroms. The appearance of superlattices was accompanied by the formation of alumina which is excluded stoichiometrically as potassium is expelled to maintain charge neutrality around empty interstice sites (K+ + Al3+ +Si4=). One of the superlattice was successfully modelled by a structure having orthorhombic Pn21m symmetry. High resolution electron microscopy revealed extensive disorder on (010). Atomic resolution images suggest these defects are regions of empty framework intimately mixed with fully occupied interstices. Copyright (2002) Australian Society for Electron Microscopy Inc

  18. Tailoring characteristic thermal stability of Ni-Au binary nanocrystals via structure and composition engineering: theoretical insights into structural evolution and atomic inter-diffusion

    International Nuclear Information System (INIS)

    We report on the structural evolution and atomic inter-diffusion characteristics of the bimetallic Ni-Au nanocrystals (NCs) by molecular dynamics simulations studies. Our results reveal that the thermal stability dynamics of Ni-Au NCs strongly depends on the atomic configurations. By engineering the structural construction with Ni:Au = 1:1 atomic composition, compared with core-shell Au@Ni and alloy NCs, the melting point of core-shell Ni@Au NCs is significantly enhanced up to 1215 K. Unexpectedly, with atomic ratio of Au:Ni= 1:9, the melting process initiates from the atoms in the shell of Ni@Au and alloy NCs, while starts from the core of Au@Ni NCs. The corresponding features and evolution process of structural motifs, mixing and segregation are illustrated via a series of dynamic simulations videos. Moreover, our results revealed that the face centered cubic phase Au0.75Ni0.25 favorably stabilizes in NCs form but does not exist in the bulk counterpart, which elucidates the anomalies of previously reported experimental results on such bimetallic NCs

  19. Tailoring characteristic thermal stability of Ni-Au binary nanocrystals via structure and composition engineering: theoretical insights into structural evolution and atomic inter-diffusion

    Directory of Open Access Journals (Sweden)

    Bangquan Li

    2014-11-01

    Full Text Available We report on the structural evolution and atomic inter-diffusion characteristics of the bimetallic Ni-Au nanocrystals (NCs by molecular dynamics simulations studies. Our results reveal that the thermal stability dynamics of Ni-Au NCs strongly depends on the atomic configurations. By engineering the structural construction with Ni:Au = 1:1 atomic composition, compared with core-shell Au@Ni and alloy NCs, the melting point of core-shell Ni@Au NCs is significantly enhanced up to 1215 K. Unexpectedly, with atomic ratio of Au:Ni= 1:9, the melting process initiates from the atoms in the shell of Ni@Au and alloy NCs, while starts from the core of Au@Ni NCs. The corresponding features and evolution process of structural motifs, mixing and segregation are illustrated via a series of dynamic simulations videos. Moreover, our results revealed that the face centered cubic phase Au0.75Ni0.25 favorably stabilizes in NCs form but does not exist in the bulk counterpart, which elucidates the anomalies of previously reported experimental results on such bimetallic NCs.

  20. Insight into the promotion effect of pre-covered X (C, N and O) atoms on the dissociation of water on Cu(111) surface: A DFT study

    Science.gov (United States)

    Jiang, Zhao; Fang, Tao

    2016-07-01

    Based on the density functional theory together with a periodic model, the adsorption and successive dissociation of water on clean and X (X = C, N and O)-covered Cu(111) surfaces have been investigated systematically. Our results indicate that the doping of carbon, nitrogen and oxygen atoms on the clean Cu(111) surface strengthens the interaction of H2O-surface and weakens the interaction of OH-surface. The corresponding adsorption configurations of adsorbates are slightly changed. Compared to that on clean Cu(111) surface, it is revealed that the doped C, N and O atoms can promote the catalytic activity of H2O dissociation and that the adsorbed C and N atoms are beneficial for the dissociation of OH, namely, the joining of C and N atoms on Cu(111) surfaces improve the catalytic activity and selectivity for H2O complete dissociation. Among four types Cu(111) surfaces, C-covered Cu(111) is the most favorable surface both kinetically and thermodynamically.

  1. 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.

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

    Science.gov (United States)

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

    2015-12-01

    The thermal diffusion of germanium and oxygen atoms in HfO2/GeO2/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 18O-tracers composing the GeO2 underlayers diffuse within the HfO2 overlayers based on Fick's law with the low activation energy of about 0.5 eV. Although out-diffusion of the germanium atoms through HfO2 also proceeded at the low temperatures of around 200 °C, the diffusing germanium atoms preferentially segregated on the HfO2 surfaces, and the reaction was further enhanced at high temperatures with the assistance of GeO desorption. A technique to insert atomically thin AlOx interlayers between the HfO2 and GeO2 layers was proven to effectively suppress both of these independent germanium and oxygen intermixing reactions in the gate stacks.

  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)

    The thermal diffusion of germanium and oxygen atoms in HfO2/GeO2/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 18O-tracers composing the GeO2 underlayers diffuse within the HfO2 overlayers based on Fick's law with the low activation energy of about 0.5 eV. Although out-diffusion of the germanium atoms through HfO2 also proceeded at the low temperatures of around 200 °C, the diffusing germanium atoms preferentially segregated on the HfO2 surfaces, and the reaction was further enhanced at high temperatures with the assistance of GeO desorption. A technique to insert atomically thin AlOx interlayers between the HfO2 and GeO2 layers was proven to effectively suppress both of these independent germanium and oxygen intermixing reactions in the gate stacks

  4. Accurate measurement and physical insight: The X-ray extended range technique for fundamental atomic physics, condensed matter research and biological sciences

    International Nuclear Information System (INIS)

    Research in core physics or atomic and condensed matter science is increasingly relevant for diverse fields and are finding application in chemistry, engineering and biological sciences, linking to experimental research at synchrotrons, reactors and specialised facilities. Over recent synchrotron experiments and publications we have developed methods for measuring the absorption coefficient far from the edge and in the XAFS (X-ray absorption fine structure) region in neutral atoms, simple compounds and organometallics reaching accuracies of below 0.02%. This is 50-500 times more accurate than earlier methods, and 50-250 times more accurate than claimed uncertainties in theoretical computations for these systems. The data and methodology are useful for a wide range of applications, including major synchrotron and laboratory techniques relating to fine structure, near-edge analysis and standard crystallography. Experiments are sensitive to theoretical and computational issues, including correlation between convergence of electronic and atomic orbitals and wavefunctions. Hence, particularly in relation to the popular techniques of XAFS and XANES (X-ray absorption near-edge structure), this development calls for strong theoretical involvement but has great applications in solid state structural determination, catalysis and enzyme environments, active centres of biomolecules and organometallics, phase changes and fluorescence investigations and others. We discuss key features of the X-ray extended range technique (XERT) and illustrate applications.

  5. REPRINT OF: Aberration measurement in HRTEM: Implementation and diagnostic use of numerical procedures for the highly precise recognition of diffractogram patterns

    Energy Technology Data Exchange (ETDEWEB)

    Barthel, J. [Institute of Solid State Research and Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C), Forschungszentrum Juelich GmbH, D-52425 Juelich (Germany); Thust, A., E-mail: a.thust@fz-juelich.de [Institute of Solid State Research and Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C), Forschungszentrum Juelich GmbH, D-52425 Juelich (Germany)

    2011-06-15

    The precise characterisation of the instrumental imaging properties in the form of aberration parameters constitutes an almost universal necessity in quantitative HRTEM, and is underlying most hardware and software techniques established in this field. We focus in this paper on the numerical analysis of individual diffractograms as a first preparatory step for further publications on HRTEM aberration measurement. The extraction of the defocus and the 2-fold astigmatism from a diffractogram is a classical pattern recognition problem, which we believe to have solved in a near-optimum way concerning precision, speed, and robustness. The newly gained measurement precision allows us to resolve fluctuations of the defocus and the 2-fold astigmatism and to assess thereby the optical stability of electron microscopes. Quantitative stability criteria are elaborated, which may serve as helpful guidelines for daily work as well as for microscope acceptance tests. -- Research Highlights: {yields} Algorithms for the highly precise diffractogram analysis in HRTEM are introduced. {yields} AMADEUS procedure measures defocus and astigmatism with a few Angstrom precision. {yields} Aberration measurement meets the precision requirements of 0.5 A microscopy. {yields} Quantitative criteria for the optical stability of HRTEMs are introduced.

  6. REPRINT OF: Aberration measurement in HRTEM: Implementation and diagnostic use of numerical procedures for the highly precise recognition of diffractogram patterns

    International Nuclear Information System (INIS)

    The precise characterisation of the instrumental imaging properties in the form of aberration parameters constitutes an almost universal necessity in quantitative HRTEM, and is underlying most hardware and software techniques established in this field. We focus in this paper on the numerical analysis of individual diffractograms as a first preparatory step for further publications on HRTEM aberration measurement. The extraction of the defocus and the 2-fold astigmatism from a diffractogram is a classical pattern recognition problem, which we believe to have solved in a near-optimum way concerning precision, speed, and robustness. The newly gained measurement precision allows us to resolve fluctuations of the defocus and the 2-fold astigmatism and to assess thereby the optical stability of electron microscopes. Quantitative stability criteria are elaborated, which may serve as helpful guidelines for daily work as well as for microscope acceptance tests. -- Research Highlights: → Algorithms for the highly precise diffractogram analysis in HRTEM are introduced. → AMADEUS procedure measures defocus and astigmatism with a few Angstrom precision. → Aberration measurement meets the precision requirements of 0.5 A microscopy. → Quantitative criteria for the optical stability of HRTEMs are introduced.

  7. In-situ HRTEM study of the reactive carbide phase of Co/MoS{sub 2} catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Ramos, Manuel, E-mail: manuel.ramos@uacj.mx [Departamento de Física y Matemáticas, Instituto de Ingeniería y Tecnología, UACJ, 32310 Ciudad Juárez, México (Mexico); Materials Research and Technology Institute, UT-El Paso, El Paso, TX 79902 (United States); Ferrer, Domingo [Microelectronics Research Laboratory, UT-Austin, Austin, TX 78758 (United States); Martinez-Soto, Eduan [Departamento de Química, Universidad Metropolitana, San Juan, PR 00926-2602 (United States); Lopez-Lippmann, Hugo; Torres, Brenda [Materials Research and Technology Institute, UT-El Paso, El Paso, TX 79902 (United States); Berhault, Gilles [Institut de Recherches sur la Catalyse et l’Environnement, IRCELYON, CNRS, Université de Lyon, Villeurbanne 69100 (France); Chianelli, Russell R. [Materials Research and Technology Institute, UT-El Paso, El Paso, TX 79902 (United States)

    2013-04-15

    Hydrotreatment catalytic operations are commonly performed industrially by layered molybdenum sulfide promoted by cobalt or nickel in order to remove heteroelements (S, N, O) from fossil fuels and biofuels. Indeed, these heteroelements are responsible of the emission of pollutants when these fuels are used in vehicles. In this respect, previous studies made by our research group have shown that the active phase under steady state conditions is partially carbided while strong bending effects of MoS{sub 2} slabs were also observed. However, up to now, the morphology of the resulting Co/MoS{sub x}C{sub y} carbided catalyst has not been fully characterized. In the present study, for the first time, a chemical reaction between the carbon content of a TEM Cu/C grid and a freshly sulfide Co/MoS{sub 2} catalyst was in situ observed at 300 °C and 450 °C by HRTEM experimental techniques at ∼10 nm of resolution. Results indicate that bending of MoS{sub 2} layers occurred due to carbon addition on MoS{sub 2} edge sites, as observed in stabilized catalysts after HDS reaction. Using a silicon grid, only cracks of MoS{sub 2} slabs were observed without bending effect confirming the role of structural-carbon in this change of morphology.

  8. 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

  9. HRTEM in protein crystallography

    International Nuclear Information System (INIS)

    Electron microscopy/diffraction (ED/D) using spot-scan and low-dose imaging has been successfully applied to investigate microcrystals of an alpha-helical coiled-coil protein extracted from ootheca of the praying mantis. Fourier transforms of the images show resolution out to 4 Angstroems and can be used to phase the corresponding ED data which shows reflections out to 2 Aangstroems. 5 refs., 3 figs

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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

    2016-01-01

    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. PMID:27312225

  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

    2016-01-01

    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. PMID:27312225

  16. Structure of GES-1 at Atomic Resolution: Insights Into the Evolution of Carbapenamase Activity in the Class a Extended-Spectrum Beta-Lactamases

    Energy Technology Data Exchange (ETDEWEB)

    Smith, C.A.; /SLAC, SSRL; Caccamo, M.; /Notre Dame U.; Kantardjieff, K.A.; /Cal State, Fullerton; Vakulenko, S.; /Notre Dame U.

    2007-10-08

    The structure of the class A extended-spectrum {beta}-lactamase GES-1 from Klebsiella pneumoniae has been determined to 1.1 Angstrom resolution. GES-1 has the characteristic active-site disulfide bond of the carbapenemase family of {beta}-lactamases and has a structure that is very similar to those of other known carbapenemases, including NMC-A, SME-1 and KPC-2. Most residues implicated in the catalytic mechanism of this class of enzyme are present in the GES-1 active site, including Ser70, which forms a covalent bond with the carbonyl C atom of the {beta}-lactam ring of the substrate during the formation of an acyl-enzyme intermediate, Glu166, which is implicated as both the acylation and deacylation base, and Lys73, which is also implicated as the acylation base. A water molecule crucial to catalysis is observed in an identical location as in other class A {beta}-lactamases, interacting with the side chains of Ser70 and Glu166. One important residue, Asn170, also normally a ligand for the hydrolytic water, is missing from the GES-1 active site. This residue is a glycine in GES-1 and the enzyme is unable to hydrolyze imipenem. This points to this residue as being critically important in the hydrolysis of this class of {beta}-lactam substrate. This is further supported by flexible-docking studies of imipenem with in silico-generated Gly170Asn and Gly170Ser mutant GES-1 enzymes designed to mimic the active sites of imipenem-hydrolyzing point mutants GES-2 and GES-5.

  17. 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.

  18. Atomic Structure of Ultrathin Gold Nanowires.

    Science.gov (United States)

    Yu, Yi; Cui, Fan; Sun, Jianwei; Yang, Peidong

    2016-05-11

    Understanding of the atomic structure and stability of nanowires (NWs) is critical for their applications in nanotechnology, especially when the diameter of NWs reduces to ultrathin scale (1-2 nm). Here, using aberration-corrected high-resolution transmission electron microscopy (AC-HRTEM), we report a detailed atomic structure study of the ultrathin Au NWs, which are synthesized using a silane-mediated approach. The NWs contain large amounts of generalized stacking fault defects. These defects evolve upon sustained electron exposure, and simultaneously the NWs undergo necking and breaking. Quantitative strain analysis reveals the key role of strain in the breakdown process. Besides, ligand-like morphology is observed at the surface of the NWs, indicating the possibility of using AC-HRTEM for surface ligand imaging. Moreover, the coalescence dynamic of ultrathin Au NWs is demonstrated by in situ observations. This work provides a comprehensive understanding of the structure of ultrathin metal NWs at atomic-scale and could have important implications for their applications. PMID:27071038

  19. Atomic resolution imaging of ferroelectric domains

    International Nuclear Information System (INIS)

    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

  20. Single atom electrochemical and atomic analytics

    Science.gov (United States)

    Vasudevan, Rama

    In the past decade, advances in electron and scanning-probe based microscopies have led to a wealth of imaging and spectroscopic data with atomic resolution, yielding substantial insight into local physics and chemistry in a diverse range of systems such as oxide catalysts, multiferroics, manganites, and 2D materials. However, typical analysis of atomically resolved images is limited, despite the fact that image intensities and distortions of the atoms from their idealized positions contain unique information on the physical and chemical properties inherent to the system. Here, we present approaches to data mine atomically resolved images in oxides, specifically in the hole-doped manganite La5/8Ca3/8MnO3, on epitaxial films studied by in-situ scanning tunnelling microscopy (STM). Through application of bias to the STM tip, atomic-scale electrochemistry is demonstrated on the manganite surface. STM images are then further analyzed through a suite of algorithms including 2D autocorrelations, sliding window Fourier transforms, and others, and can be combined with basic thermodynamic modelling to reveal relevant physical and chemical descriptors including segregation energies, existence and strength of atomic-scale diffusion barriers, surface energies and sub-surface chemical species identification. These approaches promise to provide tremendous insights from atomically resolved functional imaging, can provide relevant thermodynamic parameters, and auger well for use with first-principles calculations to yield quantitative atomic-level chemical identification and structure-property relations. This research was sponsored by the Division of Materials Sciences and Engineering, BES, DOE. Research was conducted at the Center for Nanophase Materials Sciences, which also provided support and is a DOE Office of Science User Facility.

  1. Investigation of the Interactions and Bonding between Carbon and Group VIII Metals at the Atomic Scale.

    Science.gov (United States)

    Zoberbier, Thilo; Chamberlain, Thomas W; Biskupek, Johannes; Suyetin, Mikhail; Majouga, Alexander G; Besley, Elena; Kaiser, Ute; Khlobystov, Andrei N

    2016-03-23

    The nature and dynamics of bonding between Fe, Ru, Os, and single-walled carbon nanotubes (SWNTs) is studied by aberration-corrected high-resolution transmission electron microscopy (AC-HRTEM). The metals catalyze a wide variety of different transformations ranging from ejection of carbon atoms from the nanotube sidewall to the formation of hollow carbon shells or metal carbide within the SWNT, depending on the nature of the metal. The electron beam of AC-HRTEM serves the dual purpose of providing energy to the specimen and simultaneously enabling imaging of chemical transformations. Careful control of the electron beam parameters, energy, flux, and dose allowed direct comparison between the metals, demonstrating that their chemical reactions with SWNTs are determined by a balance between the cohesive energy of the metal particles and the strength of the metal-carbon σ- or π-bonds. The pathways of transformations of a given metal can be drastically changed by applying different electron energies (80, 40, or 20 keV), thus demonstrating AC-HRTEM as a new tool to direct and study chemical reactions. The understanding of interactions and bonding between SWNT and metals revealed by AC-HRTEM at the atomic level has important implications for nanotube-based electronic devices and catalysis. PMID:26848826

  2. Consumer Insights

    Institute of Scientific and Technical Information of China (English)

    JANKOT

    2004-01-01

    Fang Jun, the head of consumer and market insights of Unilever Shanghai, has summarized his early life as a market in two sentences: rush about to study market changes;act all day to observe consumer behavior. And now?"Tell stories, conduct interviews and piece together different data; calculate numbers,build models and write reports."

  3. Science insights.

    Science.gov (United States)

    Tanabe, Kazuyuki

    2015-06-01

    "Below is an essay by Prof. Tanabe originally written in Japanese. It gives an insight to Prof. Tanabe's inquiring mind and his approach to science. He also seek, as always, to inspire and nudge the young to scientific discovery". PMID:25463310

  4. Atom Chips

    CERN Document Server

    Folman, R; Cassettari, D; Hessmo, B; Maier, T; Schmiedmayer, J; Folman, Ron; Krüger, Peter; Cassettari, Donatella; Hessmo, Björn; Maier, Thomas

    1999-01-01

    Atoms can be trapped and guided using nano-fabricated wires on surfaces, achieving the scales required by quantum information proposals. These Atom Chips form the basis for robust and widespread applications of cold atoms ranging from atom optics to fundamental questions in mesoscopic physics, and possibly quantum information systems.

  5. Atomic structure and orientation relations of interfaces between Ag and ZnO

    OpenAIRE

    Vellinga, W. P.; de Hosson, J.T.M.

    1997-01-01

    This paper presents the results of investigations of Ag-ZnO interfaces, produced by internal oxidation of an Ag-Zn alloy. ZnO precipitates with the wurtzite structure were found exhibiting mainly one orientation relation with the Ag matrix. However, closely related ORs were found, rotated by small angles from that orientation relation. The atomic structures of several interfaces surrounding these precipitates were studied and compared using HRTEM. The paper concentrates on interfaces between ...

  6. Atomic energy

    CERN Multimedia

    1996-01-01

    Interviews following the 1991 co-operation Agreement between the Department of Atomic Energy (DAE) of the Government of India and the European Organization for Nuclear Research (CERN) concerning the participation in the Large Hadron Collider Project (LHC) . With Chidambaram, R, Chairman, Atomic Energy Commission and Secretary, Department of Atomic Energy, Department of Atomic Energy (DAE) of the Government of India and Professor Llewellyn-Smith, Christopher H, Director-General, CERN.

  7. Atom chips

    CERN Document Server

    Reichel, Jakob

    2010-01-01

    This book provides a stimulating and multifaceted picture of a rapidly developing field. The first part reviews fundamentals of atom chip research in tutorial style, while subsequent parts focus on the topics of atom-surface interaction, coherence on atom chips, and possible future directions of atom chip research. The articles are written by leading researchers in the field in their characteristic and individual styles.

  8. 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.

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

    International Nuclear Information System (INIS)

    The nanoparticles in an Al-alloyed high-Cr oxide dispersion strengthened (ODS) steel with Zr addition, i.e., SOC-14 (Fe–15Cr–2W–0.1Ti–4Al–0.63Zr–0.35Y2O3), have been examined by transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). Relative to an Al-alloyed high-Cr oxide ODS steel without Zr addition, i.e., SOC-9 (Fe–15.5Cr–2W–0.1Ti–4Al–0.35Y2O3), the dispersion morphology and coherency of the oxide nanoparticles in SOC-14 were significantly improved. Almost all the small nanoparticles (diameter 4Zr3O12 oxides and coherent with the bcc steel matrix, with semi-coherent orthorhombic Y2TiO5 oxides occasionally detected. The large particles were mainly identified as tetragonal or cubic ZrO2 oxide. The results are compared with those of SOC-9 with a brief discussion of the mechanisms of the unusual thermal and irradiation stabilities of the oxides as well as the extraordinary corrosion resistance, excellent irradiation tolerance and superior strength of SOC-14

  10. 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.

  11. 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

  12. Atomic polarizabilities

    International Nuclear Information System (INIS)

    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

  13. Atom interferometry

    International Nuclear Information System (INIS)

    We will first present a development of the fundamental principles of atom interferometers. Next we will discuss a few of the various methods now available to split and recombine atomic De Broglie waves, with special emphasis on atom interferometers based on optical pulses. We will also be particularly concerned with high precision interferometers with long measurement times such those made with atomic fountains. The application of atom interferometry to the measurement of the acceleration due to gravity will be detailed. We will also develop the atom interferometry based on adiabatic transfer and we will apply it to the measurement of the photon recoil in the case of the Doppler shift of an atomic resonance caused by the momentum recoil from an absorbed photon. Finally the outlook of future developments will be given. (A.C.)

  14. Schroedinger atom

    International Nuclear Information System (INIS)

    Features of an electrodynamical interpretation suggested by Schroedinger for the wave function are discribed. According to this conception electron charges are continuously distributed all over the volume of an atomic system. The proof is given that classical electrodynamics keeps its action inside atom. Schroedinger's atom has been shown to be the only model in which electrones do not lose their energy for emission when they move around nucleus. A significance of the distributed electron charge self-field is estimated. Practical applications of this conception have been noted including the new trend in quantum electrodynamics. Experimental and theoretical corroborations of the atom model with a continuous electron charge are adduced

  15. Atomic physics

    International Nuclear Information System (INIS)

    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 23Po,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 23Po level of helium-like krypton

  16. Characterization of Al2O3 Thin Films on GaAs Substrate Grown by Atomic Layer Deposition

    Institute of Scientific and Technical Information of China (English)

    LU Hong-Liang; LI Yan-Bo; XU Min; DING Shi-Jin; SUN Liang; ZHANG Wei; WANG Li-Kang

    2006-01-01

    @@ Al2O3 thin films are grown by atomic layer deposition on GaAs substrates at 300℃. The structural properties of the Al2O3 thin film and the Al2O3/GaAs interface are characterized using x-ray diffraction (XRD), highresolution transmission electron microscopy (HRTEM), and x-ray photoelectron spectroscopy (XPS). The XRD results show that the as-deposited Al2O3 film is amorphous. For 30 atomic layer deposition growth cycles, the thicknesses of the Al2O3 thin film and the interface layer from the HRTEM are 3.3nm and 0.5nm, respectively.XPS analyses reveal that the Al2O3/GaAs interface is almost free from As2O3.

  17. Atomic physics

    CERN Document Server

    Born, Max

    1989-01-01

    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.

  18. Collision-produced atomic states

    International Nuclear Information System (INIS)

    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)

  19. Atomic scale structure investigations of epitaxial Fe/Cr multilayers

    International Nuclear Information System (INIS)

    Fe/Cr multilayers were deposited by molecular beam epitaxy on the MgO(1 0 0) substrate. Structural properties of the samples were analyzed by low energy electron diffraction, high resolution transmission electron microscopy (HRTEM), as well as by X-ray reflectivity, conversion electron Mössbauer spectroscopy (CEMS) and Auger electron spectroscopy. Investigations revealed multilayered system built of well-ordered Fe and Cr thin films with (1 0 0) orientation. A high geometrical perfection of the system, i.e. planar form of interfaces and reproducible thickness of layers, was also proven. Fe/Cr interface roughness was determined to be 2–3 atomic layers. CEMS studies allowed to analyze at atomic scale the structure of buried Fe/Cr interfaces, as well as to distinguish origin of interface roughness. Roughnesses resulting from interface corrugations and from the Fe–Cr interdiffusion at interfaces were observed. Fe/Cr multilayers showed strong antiferromagnetic coupling of Fe layers.

  20. 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...

  1. Enthalpies of formation and atomization energies of rare earth halides

    International Nuclear Information System (INIS)

    On the basis of experimentally determined atomization energies and formation enthalpies of gaseous rare earth chlorides and theoretical insights of quantum-chemical model ''atom in a molecule'' the analysis of the known literature data on formation enthalpies and atomization energies for lanthanide fluorides, bromides and iodides has been carried out and their values are assessed for unexplored molecules

  2. Atomic secrecy

    International Nuclear Information System (INIS)

    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

  3. Atomic Insight into the Lithium Storage and Diffusion Mechanism of SiO2/Al2O3 Electrodes of Lithium Ion Batteries: ReaxFF Reactive Force Field Modeling.

    Science.gov (United States)

    Ostadhossein, Alireza; Kim, Sung-Yup; Cubuk, Ekin D; Qi, Yue; van Duin, Adri C T

    2016-04-01

    Atomically deposited layers of SiO2 and Al2O3 have been recognized as promising coating materials to buffer the volumetric expansion and capacity retention upon the chemo-mechanical cycling of the nanostructured silicon- (Si-) based electrodes. Furthermore, silica (SiO2) is known as a promising candidate for the anode of next-generation lithium ion batteries (LIBs) due to its superior specific charge capacity and low discharge potential similar to Si anodes. In order to describe Li-transport in mixed silica/alumina/silicon systems we developed a ReaxFF potential for Li-Si-O-Al interactions. Using this potential, a series of hybrid grand canonical Monte Carlo (GCMC) and molecular dynamic (MD) simulations were carried out to probe the lithiation behavior of silica structures. The Li transport through both crystalline and amorphous silica was evaluated using the newly optimized force field. The anisotropic diffusivity of Li in crystalline silica cases is demonstrated. The ReaxFF diffusion study also verifies the transferability of the new force field from crystalline to amorphous phases. Our simulation results indicates the capability of the developed force field to examine the energetics and kinetics of lithiation as well as Li transportation within the crystalline/amorphous silica and alumina phases and provide a fundamental understanding on the lithiation reactions involved in the Si electrodes covered by silica/alumina coating layers. PMID:26978039

  4. 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

  5. INSIGHT, PSYCHOPATHOLOGY & SCHIZOPHRENIA

    OpenAIRE

    Armstrongh, K.P. Lincoln; Chandrasekaran, R.; Perme, Bojir

    2002-01-01

    25 inpatients with schizophrenia were examined to explore the relationship between insight and psychopathology and illness severity over a four-week period. The average degree of insight improved irrespective of the type of recovery. There was no consistent relationship between the changes in insight and changes in psychopathology. The severity of mental illness and awareness of mental disorder showed a semi-independent pattern of association. It is concluded that insight operates to some ext...

  6. Atoms as Qed bound atoms

    International Nuclear Information System (INIS)

    The relevance of Quantum Electrodynamics (Qed) in contemporary atomic structure theory is reviewed. Recent experimental advances allow both the production of heavy ions of high charge as well as the measurement of atomic properties with a precision never achieved before. The description of heavy atoms with few electrons via the successive incorporation of one, two, etcetera photons in a rigorous manner and within the bound state Furry representation of Qed is technically feasible. For many-electron atoms the many-body (correlation) effects are very important and it is practically impossible to evaluate all the relevant Feynman diagrams to the required accuracy. Thus, it is necessary to develop a theoretical scheme in which the radiative and nonradiative effects are taken into account in an effective way making emphasis in electronic correlation. Preserving gauge invariance, and avoiding both continuum dissolution and variational collapse are basic problems that must be solved when using effective potential methods and finite-basis representations of them. In this context, we shall discuss advances and problems in the description of atoms as Qed bound states. (Author)

  7. Atomic structures of Zr-based metallic glasses

    Institute of Scientific and Technical Information of China (English)

    HUI XiDong; LIU Xiongdun; GAO Rui; HOU HuaiYu; FANG HuaZhi; LIU ZiKui; CHEN GuoLiang

    2008-01-01

    The atomic structures of Zr-Ni and Zr-Ti-Al-Cu-Ni metallic glasses were investigated by using classical molecular dynamic (MD), reverse Monte Carlo (RMC), ab initio MD (AIMD) simulations and high resolution transmission electron microscopy (HRTEM) techniques. We focused on the short-range order (SRO) and medium-range order (MRO) in the glassy structure. It is shown that there are icosahedral, FCC- and BCC-type SROs in the Zr-based metallic glasses. A structural model, characterized by imperfect ordered packing (IOP), was proposed based on the MD simulation and confirmed by the HRTEM observation. Furthermore, the evolution from lOP to nanocrystal during the crystallization of metallic glasses was also ex-plored. It is found that the growth from IOP to nanocrystal proceeds through three distinct stages: the formation of quasi-ordered structure with one-dimensional (1 D) periodicity, then 2D periodicity, and finally the formation of 3D nanocrystals. It is also noted that these three growth steps are crosslinked.

  8. Atomic structures of Zr-based metallic glasses

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The atomic structures of Zr-Ni and Zr-Ti-Al-Cu-Ni metallic glasses were investigated by using classical molecular dynamic (MD),reverse Monte Carlo (RMC),ab initio MD (AIMD) simulations and high resolution transmission electron microscopy (HRTEM) techniques. We focused on the short-range order (SRO) and medium-range order (MRO) in the glassy structure. It is shown that there are icosahedral,FCC-and BCC-type SROs in the Zr-based metallic glasses. A structural model,characterized by imperfect ordered packing (IOP),was proposed based on the MD simulation and confirmed by the HRTEM observation. Furthermore,the evolution from IOP to nanocrystal during the crystallization of metallic glasses was also ex-plored. It is found that the growth from IOP to nanocrystal proceeds through three distinct stages: the formation of quasi-ordered structure with one-dimensional (1D) periodicity,then 2D periodicity,and finally the formation of 3D nanocrystals. It is also noted that these three growth steps are crosslinked.

  9. Atomic structure and electronic states of extended defects in silicon

    International Nuclear Information System (INIS)

    Defects in silicon like dislocations, grain boundaries, silicide precipitates, etc. are spatially extended and associated with a large number of electronic states in the band gap. Our knowledge on the relation between atomic structure and electronic states of these extended defects presently starts to grow by applying high-resolution electron microscopy (HRTEM) and deep level transient spectroscopy (DLTS) in combination with numerical simulations. While by means of HRTEM details of structure can be studied, DLTS has been shown to allow for a classification of extended defect states into bandlike and localized. Moreover, this method opens the perspective to distinguish between trap-like and recombination-like electrical activity. In this paper, we emphasize the particular role of nickel and copper silicide precipitates, since in their cases structural features could be successfully related to specific DLTS line characteristics. Rapid quenching from high diffusion temperatures prevents decoration of platelet-shaped NiSi2 and Cu3Si precipitates with other impurities. This allows to study their intrinsic electrical activity. Comparison of experimental results with numerical simulations enables identification of structural units originating electrical activity and yields first evaluations of extended defect parameters. Accordingly, e.g., in the case of as-quenched NiSi2 it is the dislocation bounding the platelet that provides a one-dimensional distribution of deep electronic states

  10. 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.

  11. A single-crystal x-ray and HRTEM study of the heavy-fermion compound YbCu4.5

    International Nuclear Information System (INIS)

    The title compound crystallizes with monoclinic symmetry. Its structure derives from the cubic AuBe5-type structure via the introduction of planar defects parallel to {ℎℎℎ} which lead to a nearly orthogonal ∼7x7x6.5 supercell having the cell parameters a8=48.961(20) A, b8=48.994(4) A, c8=45.643(4) A, β=91.24(1) deg. A four-dimensional structural analysis reveals a quasi-linear modulation of the atomic positions and occupancies of ytterbium and copper along c8. On the basis of this result and the electron microscopy images, a three-dimensional model of the superstructure was constructed in space group C2. The model contains 7448 atoms per unit cell which are distributed over 350 Yb sites and 1519 Cu sites. It has the overall composition YbCu4.43, contains short Yb-Yb distances, and is consistent with the chemical and physical properties. (author)

  12. 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.

  13. Oedipus and insight.

    Science.gov (United States)

    Michels, R

    1986-10-01

    Insight is a core concept in psychoanalytic theory. The Oedipus myth has been a central metaphor in the evolution of psychoanalytic theory, particularly the psychoanalytic theory of development. Similarly, Sophocles' drama, its relation to the myth, and its repeated reinterpretation throughout the ages provide a valuable metaphor for our understanding of the role of insight in psychoanalysis and in development. We may have underestimated the importance of insight in normal development while oversimplifying its significance as an agent of therapeutic change. PMID:3797556

  14. Dreaming and insight

    OpenAIRE

    Edwards, Christopher L; Perrine Marie RUBY; 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 ...

  15. Exotic atoms

    International Nuclear Information System (INIS)

    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

  16. Atomic Clocks

    Science.gov (United States)

    Wynands, Robert

    Time is a strange thing. On the one hand it is arguably the most inaccessible physical phenomenon of all: both in that it is impossible to manipulate or modify—for all we know—and in that even after thousands of years mankind's philosophers still have not found a fully satisfying way to understand it. On the other hand, no other quantity can be measured with greater precision. Today's atomic clocks allow us to reproduce the length of the second as the SI unit of time with an uncertainty of a few parts in 1016—orders of magnitude better than any other quantity. In a sense, one can say [1

  17. Single atom measurement and atomic manipulation using atomic force microscope

    International Nuclear Information System (INIS)

    This paper explains studies to measure atomic force as the force linking an atom and atom, using an atomic force microscope (AFM). First, it describes the principle and device configuration of AFM, and as an example of the atomic force measurement of Si atoms on the surface of Si(111)-(7x7), it describes the technique to measure atomic force using AFM, as well as the uncertainty of probe tip against atomic force. In addition, it describes the following items on the measurement results of chemical bonding force: (1) chemical bonding force vs physical force and chemical bonding force vs current on the surface of Si(111)-(7x7), (2) chemical bonding force and element dependence on the surface of Si/Sn(111)-(√3x√3), (3) atomic manipulation based on AMF, and (4) relationship between atomic manipulation and the size of chemical bonding force with a probe. (A.O.)

  18. 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.

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

    International Nuclear Information System (INIS)

    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−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−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

  20. Revealing the atomic and electronic structure of a SrTiO3/LaNiO3/SrTiO3 heterostructure interface

    International Nuclear Information System (INIS)

    The atomic structures of SrTiO3 (STO)/LaNiO3 (LNO)/STO heterostructure interfaces were investigated by spherical aberration-corrected (CS) (scanning) transmission electron microscopy. Atomic displacement and lattice distortion measurements and electron energy loss spectroscopy (EELS) were used to quantitatively analyze the distortion of the interfacial octahedra and the bond length at the interfaces. Combined with high-resolution transmission electron microscopy (HRTEM) and scanning transmission electron microscopy analyses, two distinct interfacial atomic terminating layers are unambiguously determined. Ensuing quantitative HRTEM measurements revealed that the Ni-O bond length in the interfacial octahedral is elongated at the bottom interface (–NiO2-SrO–). Atomic displacement shows structural relaxation effects when crossing the interfaces and lattice distortions across the interface is more pronounced in LNO than in STO. The Ti/O atomic ratio, La and Ti relative atomic ratio as derived by EELS quantification indicate non-stoichiometric composition at the interfaces. Distinct fine structures of Ti-L2,3 edge and O-K edge at the bottom and top interfaces are observed. By comparison, we are able to estimate Ti valency at both interfaces. Combining the structural distortions and Ti valency, the polar discontinuity and charge transfer at the interfaces are discussed

  1. Insight cognitif et schizophrenie

    OpenAIRE

    W. El-Hage; Lafay, N.; Wassouf, I.; Jaafari, N.

    2011-01-01

    Resume La schizophrenie est souvent associee a une meconnaissance du trouble severe et persistante. Ce deficit d?insight est correle a l?hypofrontalite mais independant du pronostic de la maladie ou du quotient intellectuel. L?insight cognitif est defini comme la difference entre la capacite de reflexion sur soi et la certitude dans cette reflexion. Cette capacite est trouvee diminuee dans la schizophrenie mais augmentee en cas de depression. Ainsi, la schizophrenie avec comorbidit...

  2. "Bohr's Atomic Model."

    Science.gov (United States)

    Willden, Jeff

    2001-01-01

    "Bohr's Atomic Model" is a small interactive multimedia program that introduces the viewer to a simplified model of the atom. This interactive simulation lets students build an atom using an atomic construction set. The underlying design methodology for "Bohr's Atomic Model" is model-centered instruction, which means the central model of the…

  3. 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)

    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 Si1-xCx nanocomposites was mixed with Si nanoparticles and C atoms embedded in a SiO2 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 Si1-xCx nanocomposites mixed with Si nanoparticles and C atoms existed in almost all regions of the SiO2 layer. The formation mechanism of Si nanoparticles and the transformation mechanism of n-butyl terminated Si nanoparticles embedded into Si1-xCx 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.

  4. Atomic Energy Basics, Understanding the Atom Series.

    Science.gov (United States)

    Atomic Energy Commission, Oak Ridge, TN. Div. of Technical Information.

    This booklet is part of the "Understanding the Atom Series," though it is a later edition and not included in the original set of 51 booklets. A basic survey of the principles of nuclear energy and most important applications are provided. These major topics are examined: matter has molecules and atoms, the atom has electrons, the nucleus,…

  5. Characterization of atomic-level structure in Fe-based amorphous and nanocrystalline alloy by experimental and modeling methods

    Energy Technology Data Exchange (ETDEWEB)

    Babilas, Rafał, E-mail: rafal.babilas@polsl.pl

    2015-09-15

    The atomic structure of Fe{sub 70}Nb{sub 10}B{sub 20} alloy in “as-cast” state and after annealing was investigated using high-energy X-ray diffraction (XRD), Mössbauer spectroscopy (MS) and high resolution transmission electron microscopy (HRTEM). The HRTEM observations allowed to indicate some medium-range order (MRO) regions about 2 nm in size and formation of some kinds of short-range order (SRO) structures represented by atomic clusters with diameter ca. 0.5 nm. The Reverse Monte Carlo (RMC) method basing on the results of XRD measurements was used in modeling the atomic structure of Fe-based alloy. The structural model was described by peak values of partial pair correlation functions and coordination numbers determined by Mössbauer spectroscopy investigations. The three-dimensional configuration box of atoms was obtained from the RMC simulation and the representative Fe-centered clusters were taken from the calculated structure. According to the Gonser et al. approach, the measured spectra of alloy studied were decomposed into 5 subspectra representing average Fe–Fe coordination numbers. Basing on the results of disaccommodation of magnetic permeability, which is sensitive to the short order of the random packing of atoms, it was stated that an occurrence of free volume is not detected after nanocrystallization process. - Highlights: • Atomic cluster model of amorphous structure was proposed for studied glassy alloy. • Short range order (ca. 0.5 nm) regions interpreted as clusters were identified by HREM. • Clusters correspond to coordination numbers (N = 4,6,8,9) calculated by using Gonser approach. • Medium-range order (ca. 2 nm) could be referred to few atomic clusters. • SRO regions are able to grow up as nuclei of crystalline bcc Fe and iron borides. • Crystalline particles have spherical morphology with an average diameter of 20 nm.

  6. Characterization of atomic-level structure in Fe-based amorphous and nanocrystalline alloy by experimental and modeling methods

    International Nuclear Information System (INIS)

    The atomic structure of Fe70Nb10B20 alloy in “as-cast” state and after annealing was investigated using high-energy X-ray diffraction (XRD), Mössbauer spectroscopy (MS) and high resolution transmission electron microscopy (HRTEM). The HRTEM observations allowed to indicate some medium-range order (MRO) regions about 2 nm in size and formation of some kinds of short-range order (SRO) structures represented by atomic clusters with diameter ca. 0.5 nm. The Reverse Monte Carlo (RMC) method basing on the results of XRD measurements was used in modeling the atomic structure of Fe-based alloy. The structural model was described by peak values of partial pair correlation functions and coordination numbers determined by Mössbauer spectroscopy investigations. The three-dimensional configuration box of atoms was obtained from the RMC simulation and the representative Fe-centered clusters were taken from the calculated structure. According to the Gonser et al. approach, the measured spectra of alloy studied were decomposed into 5 subspectra representing average Fe–Fe coordination numbers. Basing on the results of disaccommodation of magnetic permeability, which is sensitive to the short order of the random packing of atoms, it was stated that an occurrence of free volume is not detected after nanocrystallization process. - Highlights: • Atomic cluster model of amorphous structure was proposed for studied glassy alloy. • Short range order (ca. 0.5 nm) regions interpreted as clusters were identified by HREM. • Clusters correspond to coordination numbers (N = 4,6,8,9) calculated by using Gonser approach. • Medium-range order (ca. 2 nm) could be referred to few atomic clusters. • SRO regions are able to grow up as nuclei of crystalline bcc Fe and iron borides. • Crystalline particles have spherical morphology with an average diameter of 20 nm

  7. Teach us atom structure

    International Nuclear Information System (INIS)

    This book is written to teach atom structure in very easy way. It is divided into nine chapters, which indicates what is the components of matter? when we divide matter continuously, it becomes atom, what did atom look like? particles comprised of matter is not only atom, discover of particles comprised of atom, symbol of element, various radiation, form alchemy to nuclear transmutation, shape of atom is evolving. It also has various pictures in each chapters to explain easily.

  8. Teach us atom structure

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Suh Yeon

    2006-08-15

    This book is written to teach atom structure in very easy way. It is divided into nine chapters, which indicates what is the components of matter? when we divide matter continuously, it becomes atom, what did atom look like? particles comprised of matter is not only atom, discover of particles comprised of atom, symbol of element, various radiation, form alchemy to nuclear transmutation, shape of atom is evolving. It also has various pictures in each chapters to explain easily.

  9. Dreaming and insight

    Directory of Open Access Journals (Sweden)

    Christopher L Edwards

    2013-12-01

    Full Text Available 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. 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.

  10. 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

  11. Atomic phase diagram

    Institute of Scientific and Technical Information of China (English)

    LI Shichun

    2004-01-01

    Based on the Thomas-Fermi-Dirac-Cheng model, atomic phase diagram or electron density versus atomic radius diagram describing the interaction properties of atoms of different kinds in equilibrium state is developed. Atomic phase diagram is established based on the two-atoms model. Besides atomic radius, electron density and continuity condition for electron density on interfaces between atoms, the lever law of atomic phase diagram involving other physical parameters is taken into account, such as the binding energy, for the sake of simplicity.

  12. Thin Film of Perovskite Oxide with Atomic Scale p-n Junctions

    Institute of Scientific and Technical Information of China (English)

    HU Bin; HUANG Ke-ke; HOU Chang-min; YUAN Hong-ming; PANG Guang-sheng; FENG Shou-hua

    2012-01-01

    Thin films of perovskite manganese oxide La0.66Ca0.29K0.05MnO3(LCKMO) on Au/ITO(ITO=indium tin oxide) substrates were prepared by off-axis radio frequency magnetron sputtering and characterized by X-ray diffraction(XRD),high-resolution transmission electron microscopy(HRTEM),and conductive atomic force microscopy (C-AFM) at room temperature.The thin films with thickness ranged from 100 nm to 300 nm basically show cubic structures with a=0.3886 nm,the same as that of the raw material used,but the structures are highly modulated.C-AFM results revealed that the atomic scale p-n junction feature of the thin films was the same as that of the single crystals.The preparation of the thin films thus further confirms the possibility of their application extending from micrometer-sized single crystals to macroscopic thin film.

  13. 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

  14. Atomizer design for viscous-melt atomization

    Energy Technology Data Exchange (ETDEWEB)

    Czisch, C. [Chemical Engineering Department, University Bremen, Badgasteiner Str. 3, 28359 Bremen (Germany); Fritsching, U. [Chemical Engineering Department, University Bremen, Badgasteiner Str. 3, 28359 Bremen (Germany)], E-mail: ufri@iwt.uni-bremen.de

    2008-03-25

    The development of a gas atomization unit is introduced, which utilizes characteristic flow effects for efficient fragmentation of viscous liquids and melts. The proposed device combines a classical rotary atomizer with an external mixing gas atomizer. Here, the liquid stream is first transformed into a thin liquid sheet before disintegration. Thereby the specific surface energy is increased without breakup. The movement of the free flowing liquid film is controlled by the local gas flow field in order to transport the film into the most effective atomization region. The fragmentation process itself is caused by a perpendicular impinging gas stream. Numerical flow simulations are used for the development of the hybrid atomizer construction. Experiments using viscous model liquids show that for constant air-to-liquid mass-flow ratio the particle size is reduced using the hybrid atomizer compared with a conventional gas atomizer. Results of model experiments as well as of experiments with a viscous mineral melt are discussed.

  15. Atomizer design for viscous-melt atomization

    International Nuclear Information System (INIS)

    The development of a gas atomization unit is introduced, which utilizes characteristic flow effects for efficient fragmentation of viscous liquids and melts. The proposed device combines a classical rotary atomizer with an external mixing gas atomizer. Here, the liquid stream is first transformed into a thin liquid sheet before disintegration. Thereby the specific surface energy is increased without breakup. The movement of the free flowing liquid film is controlled by the local gas flow field in order to transport the film into the most effective atomization region. The fragmentation process itself is caused by a perpendicular impinging gas stream. Numerical flow simulations are used for the development of the hybrid atomizer construction. Experiments using viscous model liquids show that for constant air-to-liquid mass-flow ratio the particle size is reduced using the hybrid atomizer compared with a conventional gas atomizer. Results of model experiments as well as of experiments with a viscous mineral melt are discussed

  16. Cold Matter Assembled Atom-by-Atom

    CERN Document Server

    Endres, Manuel; Keesling, Alexander; Levine, Harry; Anschuetz, Eric R; Krajenbrink, Alexandre; Senko, Crystal; Vuletic, Vladan; Greiner, Markus; Lukin, Mikhail D

    2016-01-01

    The realization of large-scale fully controllable quantum systems is an exciting frontier in modern physical science. We use atom-by-atom assembly to implement a novel platform for the deterministic preparation of regular arrays of individually controlled cold atoms. In our approach, a measurement and feedback procedure eliminates the entropy associated with probabilistic trap occupation and results in defect-free arrays of over 50 atoms in less than 400 ms. The technique is based on fast, real-time control of 100 optical tweezers, which we use to arrange atoms in desired geometric patterns and to maintain these configurations by replacing lost atoms with surplus atoms from a reservoir. This bottom-up approach enables controlled engineering of scalable many-body systems for quantum information processing, quantum simulations, and precision measurements.

  17. Stable atomic hydrogen: Polarized atomic beam source

    International Nuclear Information System (INIS)

    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.)

  18. Neutral atom traps.

    Energy Technology Data Exchange (ETDEWEB)

    Pack, Michael Vern

    2008-12-01

    This report describes progress in designing a neutral atom trap capable of trapping sub millikelvin atom in a magnetic trap and shuttling the atoms across the atom chip from a collection area to an optical cavity. The numerical simulation and atom chip design are discussed. Also, discussed are preliminary calculations of quantum noise sources in Kerr nonlinear optics measurements based on electromagnetically induced transparency. These types of measurements may be important for quantum nondemolition measurements at the few photon limit.

  19. MULTIPHOTON IONIZATION OF ATOMS

    OpenAIRE

    Mainfray, G.

    1985-01-01

    Multiphoton ionization of one-electron atoms, such as atomic hydrogen and alkaline atoms, is well understood and correctly described by rigorous theoretical models. The present paper will be devoted to collisionless multiphoton ionization of many-electron atoms as rare gases. It induces removal of several electrons and the production of multiply charged ions. Up to Xe5+ ions are produced in Xe atoms. Doubly charged ions can be produced, either by simultaneous excitation of two electrons, or b...

  20. The infancy of atomic physics Hercules in his cradle

    CERN Document Server

    Keller, Alex

    2006-01-01

    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

  1. 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.

  2. Trouble, Strategic Insights

    OpenAIRE

    Moran, Daniel

    2002-01-01

    Strategic Insights are authored monthly by analysts with the Center for Contemporary Conflict (CCC). The CCC is the research arm of the National Security Affairs Department at the Naval Postgraduate School in Monterey, California. The views expressed here are those of the author and do not necessarily represent the views of the Naval Postgraduate School, the Department of Defense, or the U.S. Government.

  3. Update on INSIGHTS Development

    Energy Technology Data Exchange (ETDEWEB)

    Not Listed; Eric Burgett

    2011-09-01

    INSIGHTS is a transformational separate effects testing capability to perform in situ irradiation studies and characterization of the microscale behavior of nuclear fuel materials under a wide variety of in-pile conditions. Separate effects testing including growth, irradiation, and monitoring of these materials, and encompasses the full science based approach for fuels development from the nanoscale to the mesoscale behavior of the sample material and other defects driven by the modeling and simulation efforts of INL.

  4. The politics of insight.

    Science.gov (United States)

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

    2016-06-01

    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

  5. 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

  6. 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...

  7. 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...

  8. Atomic Physics 15: Proceedings of the Fifteenth International Conference on Atomic Physics.

    Science.gov (United States)

    van Linden van den Heuvell, H. B.; Walraven, J. T. M.; Reynolds, M. W.

    1997-07-01

    The Table of Contents for the full book PDF is as follows: * Preface * Generation of a "Schrödinger cat" of radiation and observation of its decoherence * Synthesis of entangled states and quantum computing * Entangled states of atomic ions for quantum metrology and computation * Entanglement and indistinguishability: Coherence experiments with photon pairs and triplets * Atom optics as a testing ground for quantum chaos * Coherent ultra-bright XUV lasers and harmonics * Hollow atoms * Interdisciplinary experiments with polarized noble gases * The creation and study of Bose-Einstein condensation in a cold alkali vapor * oscopic quantum phenomena in trapped Bose-condensed gases * Doppler-free spectroscopy of trapped atomic hydrogen * QED and the ground state of helium * Towards coherent atomic samples using laser cooling * Bose-Einstein condensation of a weakly-interacting gas * Zeeman and his contemporaries: Dutch physics around 1900 * Zeeman's great discovery * The Zeeman effect: A tool for atom manipulation * The Zeeman effect a century later: New insights into classical physics * QED effects in few-electron high-Z systems * Lamb shift experiments on high-Z one- and two-electron systems * Fundamental constants of nature * Response of atoms in photonic lattices * Hydrogen-like systems and quantum electrodynamics * New experiments with atomic lattices bound by light * Bloch oscillations of atoms in an optical potential * Quantum decoherence and inertial sensing with atom interferometers * Quantum effects in He clusters * Atoms in super-intense radiation fields * Wave packet dynamics of excited atomic electrons in intense laser fields * Nonlinear laser-electron scattering * Comparing the antiproton and proton and progress toward cold antihydrogen * Author Index

  9. THE ORNL ATOM PROBE

    OpenAIRE

    Miller, M

    1986-01-01

    The ORNL Atom Probe is a microanalytical tool for studies in materials science. The instrument is a combination of a customized version of the vacuum system of the VG FIM-100 atom probe, an ORNL-designed microcomputer-controlled digital timing system, and a double curved CEMA Imaging Atom Probe detector. The atom probe combines four instruments into one - namely a field ion microscope, an energy compensated time-of-flight mass spectrometer, an imaging atom probe, and a pulsed laser atom probe.

  10. Electron Cyclotron Resonance Plasma-Assisted Atomic Layer Deposition of Amorphous Al2O3 Thin Films

    International Nuclear Information System (INIS)

    Without extra heating, Al2O3 thin films were deposited on a hydrogen-terminated Si substrate etched in hydrofluoric acid by using a self-built electron cyclotron resonance (ECR) plasma-assisted atomic layer deposition (ALD) device with Al(CH3)3 (trimethylaluminum; TMA) and O2 used as precursor and oxidant, respectively. During the deposition process, Ar was introduced as a carrier and purging gas. The chemical composition and microstructure of the as-deposited Al2O3 films were characterized by using X-ray diffraction (XRD), an X-ray photoelectric spectroscope (XPS), a scanning electron microscope (SEM), an atomic force microscope (AFM) and a high-resolution transmission electron microscope (HRTEM). It achieved a growth rate of 0.24 nm/cycle, which is much higher than that deposited by thermal ALD. It was found that the smooth surface thin film was amorphous alumina, and an interfacial layer formed with a thickness of ca. 2 nm was observed between the Al2O3 film and substrate Si by HRTEM. We conclude that ECR plasma-assisted ALD can grow Al2O3 films with an excellent quality at a high growth rate at ambient temperature.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2003-07-30

    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 {approx}0.08 nm diameter. In QW s of {approx}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.

  12. Atomic Structure and Properties of Extended Defects in Silicon

    Energy Technology Data Exchange (ETDEWEB)

    Buczko, R.; Chisholm, M.F.; Kaplan, T.; Maiti, A.; Mostoller, M.; Pantelides, S.T.; Pennycook, S.J.

    1998-10-15

    The Z-contrast technique represents a new approach to high-resolution electron microscopy allowing for the first time incoherent imaging of materials on the atomic scale. The key advantages of the technique, an intrinsically higher resolution limit and directly interpretable, compositionally sensitive imaging, allow a new level of insight into the atomic configurations of extended defects in silicon. This experimental technique has been combined with theoretical calculations (a combination of first principles, tight binding, and classical methods) to extend this level of insight by obtaining the energetic and electronic structure of the defects.

  13. Handbook of hot atom chemistry

    International Nuclear Information System (INIS)

    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.)

  14. Atomic and molecular structure

    International Nuclear Information System (INIS)

    This book is a textbook for an introductory course of atomic physics for students of chemistry. After an introduction to the mathematical and physical foundations the quantum mechanical theory of atoms is described starting from simple examples of quantum mechanics. Then the atomic structure and the chemical bending are extensively discussed. This book is also suited for physicists who are especially interested in the atomic structure and the theory of chemical reactions. (HSI)

  15. Atomic Scale Plasmonic Switch

    OpenAIRE

    Emboras, A.; Niegemann, J.; Ma, P; Haffner, C; Pedersen, A.; Luisier, M.; Hafner, C; Schimmel, T.; Leuthold, J.

    2016-01-01

    The atom sets an ultimate scaling limit to Moore’s law in the electronics industry. While electronics research already explores atomic scales devices, photonics research still deals with devices at the micrometer scale. Here we demonstrate that photonic scaling, similar to electronics, is only limited by the atom. More precisely, we introduce an electrically controlled plasmonic switch operating at the atomic scale. The switch allows for fast and reproducible switching by means of the relocat...

  16. Atomizing nozzle and process

    Science.gov (United States)

    Anderson, Iver E.; Figliola, Richard S.; Molnar, Holly M.

    1992-06-30

    High pressure atomizing nozzle includes a high pressure gas manifold having a divergent expansion chamber between a gas inlet and arcuate manifold segment to minimize standing shock wave patterns in the manifold and thereby improve filling of the manifold with high pressure gas for improved melt atomization. The atomizing nozzle is especially useful in atomizing rare earth-transition metal alloys to form fine powder particles wherein a majority of the powder particles exhibit particle sizes having near-optimum magnetic properties.

  17. Antiprotonic Helium Atoms

    OpenAIRE

    Kartavtsev, O. I.

    1995-01-01

    Metastable antiprotonic helium atoms $^{3,4}\\! H\\! e\\bar pe$ have been discovered recently in experiments of the delayed annihilation of antiprotons in helium media. These exotic atoms survive for an enormous time (about tens of microseconds) and carry the extremely large total angular momentum $L\\sim 30-40$. The theoretical treatment of the intrinsic properties of antiprotonic helium atoms, their formation and collisions with atoms and molecules is discussed.

  18. Atoms Talking to SQUIDs

    OpenAIRE

    2011-01-01

    We present a scheme to couple trapped $^{87}$Rb atoms to a superconducting flux qubit through a magnetic dipole transition. We plan to trap atoms on the evanescent wave outside an ultrathin fiber to bring the atoms to less than 10 $\\mu$m above the surface of the superconductor. This hybrid setup lends itself to probing sources of decoherence in superconducting qubits. Our current plan has the intermediate goal of coupling the atoms to a superconducting LC resonator.

  19. Schroedinger cat states and multilevel atoms

    International Nuclear Information System (INIS)

    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

  20. 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.

  1. Atomic Energy Control Act

    International Nuclear Information System (INIS)

    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

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

    International Nuclear Information System (INIS)

    In this work, the characteristic inversion domain microstructures of In2O3(ZnO)m (m=30) compounds were investigated by TEM methods. At bright-atom contrast condition, atomically resolved HR-TEM images of In2O3(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 In2O3(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 In2O3(ZnO)m compounds by using phase-contrast and Z-contrast imaging at atomic resolution, In3+ atoms are determined with trigonal bi-pyramidal co-ordination and are distributed at the pyramidal IDBs. (orig.)

  3. The Atomic Manifesto: a Story in Four Quarks

    OpenAIRE

    Jones, Cliff; Lomet, David; Romanovsky, Alexander; Weikum, Gerhard; Fekete, Alan; Gaudel, Marie-Claude; Korth, Henry F.; de Lemos, Rogerio; Moss, Eliot; Rajwar, Ravi; Ramamritham, Krithi; Randell, Brian; Rodrigues, Luis

    2005-01-01

    This report summarizes the viewpoints and insights gathered in the Dagstuhl Seminar on Atomicity in System Design and Execution, which was attended by 32 people from four different scientific communities: database and transaction processing systems, fault tolerance and dependable systems, formal methods for system design and correctness reasoning, and hardware architecture and programming languages. Each community presents its position in interpreting the notion of atomicity and the existing ...

  4. Casimir effects in atomic, molecular, and optical physics

    CERN Document Server

    Babb, James F

    2010-01-01

    The long-range interaction between two atoms and the long-range interaction between an ion and an electron are compared at small and large intersystem separations. The vacuum dressed atom formalism is applied and found to provide a framework for interpretation of the similarities between the two cases. The van der Waals forces or Casimir-Polder potentials are used to obtain insight into relativistic and higher multipolar terms.

  5. Dynamic and atomic-scale understanding of the twin thickness effect on dislocation nucleation and propagation activities by in situ bending of Ni nanowires

    International Nuclear Information System (INIS)

    Although their mechanical behavior has been extensively studied, the atomic-scale deformation mechanisms of metallic nanowires (NWs) with growth twins are not completely understood. Using our own atomic-scale and dynamic mechanical testing techniques, bending experiments were conducted on single-crystalline and twin-structural Ni NWs (D = ∼40 nm) using a high-resolution transmission electron microscope (HRTEM). Atomic-scale and time-resolved dislocation nucleation and propagation activities were captured in situ. A large number of in situ HRTEM observations indicated strong effects from the twin thickness (TT) on dislocation type and glide system. In thick twin lamella (TT > ∼12 nm) and single-crystalline NWs, the plasticity was controlled by full dislocation nucleation. For NWs with twin thicknesses of ∼9 nm < TT < ∼12 nm, full and partial dislocation nucleation occurred from the free surface, and the dislocations glided on multiple systems and interacted with each other during plastic deformation. For NWs with twin thicknesses of ∼6 nm < TT < ∼9 nm, partial dislocation nucleation from the free surface and the gliding of those dislocations on the plane that intersected the twin boundaries (TBs) were the dominant plasticity events. For the NWs with twin thicknesses of ∼1 nm < TT < ∼6 nm, the plasticity was accommodated by a partial dislocation nucleation process and glide parallel to the TBs. When TT < ∼1 nm, TB migration and detwinning processes resulting from partial dislocation nucleation and glide adjacent to the TBs were frequently observed

  6. Atomic swelling upon compression

    CERN Document Server

    Dolmatov, V K

    2012-01-01

    The hydrogen atom under the pressure of a spherical penetrable confinement potential of a decreasing radius $r_{0}$ is explored, as a case study. A novel counter-intuitive effect of atomic swelling rather than shrinking with decreasing $r_{0}$ is unraveled, when $r_{0}$ reaches, and remains smaller than, a certain critical value. Upon swelling, the size of the atom is shown to increase by an order of magnitude, or more, compared to the size of the free atom. Examples of changes of photoabsorption properties of confined hydrogen atom upon its swelling are uncovered and demonstrated.

  7. Experimental and Theoretical Analysis of the Luminescence Spectroscopy of atomic Mercury and atomic Manganese isolated in Rare Gas Solids

    OpenAIRE

    Collier, Martin

    2004-01-01

    The work presented in this thesis is primarily experimental but also contains an important theoretical extension to gain further insight into the optical spectroscopy of atomic ns2 metal atoms, mercury and manganese isolated in cryogenic thin films of rare gases argon, krypton and xenon. The luminescence spectroscopy of solid-state M/RG (M = Hg and Mn; RG = Ar, Kr and Xe) samples has been recorded employing both time-integrated (steady-state) and time-resolved methods. The impe...

  8. Single Atom Plasmonic Switch

    CERN Document Server

    Emboras, Alexandros; Ma, Ping; Haffner, Christian; Luisier, Mathieu; Hafner, Christian; Schimmel, Thomas; Leuthold, Juerg

    2015-01-01

    The atom sets an ultimate scaling limit to Moores law in the electronics industry. And while electronics research already explores atomic scales devices, photonics research still deals with devices at the micrometer scale. Here we demonstrate that photonic scaling-similar to electronics-is only limited by the atom. More precisely, we introduce an electrically controlled single atom plasmonic switch. The switch allows for fast and reproducible switching by means of the relocation of an individual or at most - a few atoms in a plasmonic cavity. Depending on the location of the atom either of two distinct plasmonic cavity resonance states are supported. Experimental results show reversible digital optical switching with an extinction ration of 10 dB and operation at room temperature with femtojoule (fJ) power consumption for a single switch operation. This demonstration of a CMOS compatible, integrated quantum device allowing to control photons at the single-atom level opens intriguing perspectives for a fully i...

  9. Excited atoms. Vozbuzhdennye atomy

    Energy Technology Data Exchange (ETDEWEB)

    Smirnov, B.M.

    1982-01-01

    An examination is made of the properties of excited atoms and molecules, the processes of their formation in a gas and plasma, and the diffusion of excited atoms in a gas. A presentation is made of the processes in which excited and metastable atoms and molecules in a gas are destroyed upon collision with electrons, atoms, and molecules. A study is made of the relaxation of excited states during collisions - excitation transfer, depolarization, transitions between fine structure states, etc. Information is given on ionization that includes the participation of excited atoms - the Penning process, associative ionization. An examination is made of highly excited states of atoms and the processes that take place during their participation. The book is intended for personnel in the area of physics and chemistry of plasma, atomic and molecular physics, chemical physics as well as in allied areas of physics. 1280 references, 52 figures, 76 tables.

  10. Interferometry with atoms

    International Nuclear Information System (INIS)

    Optics and interferometry with matter waves is the art of coherently manipulating the translational motion of particles like neutrons, atoms and molecules. Coherent atom optics is an extension of techniques that were developed for manipulating internal quantum states. Applying these ideas to translational motion required the development of techniques to localize atoms and transfer population coherently between distant localities. In this view position and momentum are (continuous) quantum mechanical degrees of freedom analogous to discrete internal quantum states. In our contribution we start with an introduction into matter wave optics in sect. 1, discuss coherent atom optics and atom interferometry techniques for molecular beams in sect. 2 and for trapped atoms in sect. 3. In sect. 4 we then describe tools and experiments that allow to probe the evolution of quantum states of many-body systems by atom interference.

  11. 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.

  12. 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. PMID:23858266

  13. Atomic collisions research with excited atomic species

    International Nuclear Information System (INIS)

    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 CF2 radicals formed by electron impact dissociation in a CF4 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(23S) atoms

  14. Long range intermolecular forces in triatomic systems: connecting the atom-diatom and atom-atom-atom representations

    OpenAIRE

    Cvitas, Marko T.; Soldan, Pavel; Hutson, Jeremy M.

    2005-01-01

    The long-range forces that act between three atoms are analysed in both atom-diatom and atom-atom-atom representations. Expressions for atom-diatom dispersion coefficients are obtained in terms of 3-body nonadditive coefficients. The anisotropy of atom-diatom C_6 dispersion coefficients arises primarily from nonadditive triple-dipole and quadruple-dipole forces, while pairwise-additive forces and nonadditive triple-dipole and dipole-dipole-quadrupole forces contribute significantly to atom-di...

  15. Atomic-layer deposited thulium oxide as a passivation layer on germanium

    Energy Technology Data Exchange (ETDEWEB)

    Mitrovic, I. Z., E-mail: ivona@liverpool.ac.uk; Hall, S.; Weerakkody, A. D.; Sedghi, N. [Department of Electrical Engineering and Electronics, University of Liverpool, Brownlow Hill, Liverpool L69 3GJ (United Kingdom); Althobaiti, M.; Hesp, D.; Dhanak, V. R. [Department of Physics and Stephenson Institute for Renewable Energy, University of Liverpool, Liverpool L69 7ZF (United Kingdom); Santoni, A. [ENEA, Frascati Research Centre, via E. Fermi 45, 00044 Frascati (Italy); Chalker, P. R. [Department of Engineering, University of Liverpool, Brownlow Hill, Liverpool L69 3GH (United Kingdom); Henkel, C.; Dentoni Litta, E.; Hellström, P.-E.; Östling, M. [School of ICT, KTH Royal Institute of Technology, Isafjordsgatan 22, 164 40 Kista (Sweden); Tan, H.; Schamm-Chardon, S. [CEMES-CNRS and Université de Toulouse, nMat group, BP 94347, 31055 Toulouse Cedex 4 (France)

    2015-06-07

    A comprehensive study of atomic-layer deposited thulium oxide (Tm{sub 2}O{sub 3}) on germanium has been conducted using x-ray photoelectron spectroscopy (XPS), vacuum ultra-violet variable angle spectroscopic ellipsometry, high-resolution transmission electron microscopy (HRTEM), and electron energy-loss spectroscopy. The valence band offset is found to be 3.05 ± 0.2 eV for Tm{sub 2}O{sub 3}/p-Ge from the Tm 4d centroid and Ge 3p{sub 3/2} charge-corrected XPS core-level spectra taken at different sputtering times of a single bulk thulium oxide sample. A negligible downward band bending of ∼0.12 eV is observed during progressive differential charging of Tm 4d peaks. The optical band gap is estimated from the absorption edge and found to be 5.77 eV with an apparent Urbach tail signifying band gap tailing at ∼5.3 eV. The latter has been correlated to HRTEM and electron diffraction results corroborating the polycrystalline nature of the Tm{sub 2}O{sub 3} films. The Tm{sub 2}O{sub 3}/Ge interface is found to be rather atomically abrupt with sub-nanometer thickness. In addition, the band line-up of reference GeO{sub 2}/n-Ge stacks obtained by thermal oxidation has been discussed and derived. The observed low reactivity of thulium oxide on germanium as well as the high effective barriers for holes (∼3 eV) and electrons (∼2 eV) identify Tm{sub 2}O{sub 3} as a strong contender for interfacial layer engineering in future generations of scaled high-κ gate stacks on Ge.

  16. Shaking-induced dynamics of cold atoms in magnetic traps

    CERN Document Server

    García, I Llorente; Sinclair, C D J; Curtis, E A; Tachikawa, M; Hudson, J J; Hinds, E A

    2013-01-01

    We describe an experiment in which cold rubidium atoms, confined in an elongated magnetic trap, are excited by transverse oscillation of the trap centre. The temperature after excitation exhibits resonance as a function of the driving frequency. We measure these resonances at several different trap frequencies. In order to interpret the experiments, we develop a simple model that incorporates both collisions between atoms and the anharmonicity of the real three-dimensional trapping potential. As well as providing a precise connection between the transverse harmonic oscillation frequency and the temperature resonance frequency, this model gives insight into the heating and loss mechanisms, and into the dynamics of driven clouds of cold trapped atoms.

  17. 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

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

    Science.gov (United States)

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

    2016-07-01

    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).

  19. Graphite filter atomizer in atomic absorption spectrometry

    Science.gov (United States)

    Katskov, Dmitri A.

    2007-09-01

    Graphite filter atomizers (GFA) for electrothermal atomic absorption spectrometry (ETAAS) show substantial advantages over commonly employed electrothermal vaporizers and atomizers, tube and platform furnaces, for direct determination of high and medium volatility elements in matrices associated with strong spectral and chemical interferences. Two factors provide lower limits of detection and shorter determination cycles with the GFA: the vaporization area in the GFA is separated from the absorption volume by a porous graphite partition; the sample is distributed over a large surface of a collector in the vaporization area. These factors convert the GFA into an efficient chemical reactor. The research concerning the GFA concept, technique and analytical methodology, carried out mainly in the author's laboratory in Russia and South Africa, is reviewed. Examples of analytical applications of the GFA in AAS for analysis of organic liquids and slurries, bio-samples and food products are given. Future prospects for the GFA are discussed in connection with analyses by fast multi-element AAS.

  20. Atomic Power Safety

    Energy Technology Data Exchange (ETDEWEB)

    Hogerton, John F

    1964-01-01

    This booklet is condensed from a larger publication, -Background Information on Atomic Power Safety-, published in January 1964, by the .Atomic Industrial Forum. That publication and this abridgment were produced in recognition of the emergence of commercial atomic power as an important factor in our national economy, and of the resulting need for readily available information in nontechnical form on the characteristics of nuclear power plants and on the various measures taken during their design, construction, and operation for public safety.

  1. Atomic Oxygen Effects

    Science.gov (United States)

    Miller, Sharon K. R.

    2014-01-01

    Atomic oxygen, which is the most predominant species in low Earth orbit, is highly reactive and can break chemical bonds on the surface of a wide variety of materials leading to volatilization or surface oxidation which can result in failure of spacecraft materials and components. This presentation will give an overview of how atomic oxygen reacts with spacecraft materials, results of space exposure testing of a variety of materials, and examples of failures caused by atomic oxygen.

  2. Metal atom oxidation laser

    International Nuclear Information System (INIS)

    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

  3. Metal atom oxidation laser

    Science.gov (United States)

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

    1975-10-28

    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. (auth)

  4. Hirshfeld atom refinement

    OpenAIRE

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

    2014-01-01

    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,...

  5. Advances in atomic physics

    OpenAIRE

    Tharwat M. El-Sherbini

    2015-01-01

    Graphical abstract In this review article, important developments in the field of atomic physics are highlighted and linked to research works the author was involved in himself as a leader of the Cairo University – Atomic Physics Group. Starting from the late 1960s – when the author first engaged in research - an overview is provided of the milestones in the fascinating landscape of atomic physics.

  6. Atomic and Molecular Physics

    OpenAIRE

    Cohen-Tannoudji, Claude

    2015-01-01

    When physicists began to explore the world of atoms more precisely, as they endeavoured to understand its structure and the laws governing its behaviour, they soon encountered serious difficulties. Our intuitive concepts, based on our daily experience of the macroscopic world around us, proved to be completely erroneous on the atomic scale; the atom was incomprehensible within the framework of classical physics. In order to uncover these new mysteries, after a great deal of trial and error, e...

  7. Solar Spectroscopy: Atomic Processes

    Science.gov (United States)

    Mason, H.; Murdin, P.

    2000-11-01

    A Greek philosopher called DEMOCRITUS (c. 460-370 BC) first introduced the concept of atoms (which means indivisible). His atoms do not precisely correspond to our atoms of today, which are not indivisible, but made up of a nucleus (protons with positive charge and neutrons which have no charge) and orbiting electrons (with negative charge). Indeed, in the solar atmosphere, the temperature is suc...

  8. 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.

  9. Phantom of the atom

    Energy Technology Data Exchange (ETDEWEB)

    Jones, G.

    1988-01-28

    The paper traces the radiation work of Ernest Rutherford, the founder of nuclear physics who died fifty years ago in 1937. The work on the 'plum pudding' model of the atom, the discovery of ..cap alpha.. and ..beta.. particles, disintegration theory, transmutation, model of the atom (with a small nucleus), and disintegration of the nitrogen atom using ..cap alpha.. particles, are all briefly described. (U.K.).

  10. Law on Atomic Energy

    International Nuclear Information System (INIS)

    The Law defines the legislative foundation and concepts for peaceful uses of atomic energy in Vietnam. The Law, including 11 chapters, 93 articles and coming into force on the 1 Jan 2009, regulates utilization of atomic energy and assurance of safety and security. The Law contains issues: general provisions; measures to promote development and application of atomic energy for peaceful purposes; radiation safety, nuclear safety and security of radioactive sources, nuclear material and facilities; exploration, exploitation and processing radioactive ores; transportation, import and export of radioactive materials and nuclear equipment; atomic energy application services; declaration and licensing; response to radiation or nuclear incidents and compensation for damage caused by these incidents. (VAEC)

  11. Atomic swelling upon compression

    OpenAIRE

    Dolmatov, V. K.; King, J L

    2012-01-01

    The hydrogen atom under the pressure of a spherical penetrable confinement potential of a decreasing radius $r_{0}$ is explored, as a case study. A novel counter-intuitive effect of atomic swelling rather than shrinking with decreasing $r_{0}$ is unraveled, when $r_{0}$ reaches, and remains smaller than, a certain critical value. Upon swelling, the size of the atom is shown to increase by an order of magnitude, or more, compared to the size of the free atom. Examples of changes of photoabsorp...

  12. Deeply bound pionic atom

    International Nuclear Information System (INIS)

    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, 2Heπ-) 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.)

  13. 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.

  14. 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.

  15. Optimal arrangement of meta-atoms composing metamaterials

    Science.gov (United States)

    Chuang, Yi-Chen; Dudley, Richard; Fiddy, Michael A.

    2012-03-01

    In order to better understand how to improve the performance of a superlens, structural and geometrical arrangements of meta-atoms are investigated. Each meta-atom (i.e. the unit element composing a metamaterial) in our study is an asymmetric 3D "S"-shaped resonator. This structure radiates an enhanced scattered field at several possible resonant frequencies, some of which are out of phase with the incident wave. We retrieve the effective parameters of different metamaterials and discuss the role of meta-atom symmetries and dimensions in affecting the effective refractive index of a metamaterial slab. Relative locations and orientations of individual meta-atoms are investigated to provide desired properties with low loss despite the inevitable finite size of each meta-atom. The results presented provide insights for designing superlenses, resonant antennas, and other potential applications.

  16. 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.

  17. Evanescent Wave Atomic Mirror

    Science.gov (United States)

    Ghezali, S.; Taleb, A.

    2008-09-01

    A research project at the "Laboratoire d'électronique quantique" consists in a theoretical study of the reflection and diffraction phenomena via an atomic mirror. This poster presents the principle of an atomic mirror. Many groups in the world have constructed this type of atom optics experiments such as in Paris-Orsay-Villetaneuse (France), Stanford-Gaithersburg (USA), Munich-Heidelberg (Germany), etc. A laser beam goes into a prism with an incidence bigger than the critical incidence. It undergoes a total reflection on the plane face of the prism and then exits. The transmitted resulting wave out of the prism is evanescent and repulsive as the frequency detuning of the laser beam compared to the atomic transition δ = ωL-ω0 is positive. The cold atomic sample interacts with this evanescent wave and undergoes one or more elastic bounces by passing into backward points in its trajectory because the atoms' kinetic energy (of the order of the μeV) is less than the maximum of the dipolar potential barrier ℏΩ2/Δ where Ω is the Rabi frequency [1]. In fact, the atoms are cooled and captured in a magneto-optical trap placed at a distance of the order of the cm above the prism surface. The dipolar potential with which interact the slow atoms is obtained for a two level atom in a case of a dipolar electric transition (D2 Rubidium transition at a wavelength of 780nm delivered by a Titane-Saphir laser between a fundamental state Jf = l/2 and an excited state Je = 3/2). This potential is corrected by an attractive Van der Waals term which varies as 1/z3 in the Lennard-Jones approximation (typical atomic distance of the order of λ0/2π where λ0 is the laser wavelength) and in 1/z4 if the distance between the atom and its image in the dielectric is big in front of λ0/2π. This last case is obtained in a quantum electrodynamic calculation by taking into account an orthornormal base [2]. We'll examine the role of spontaneous emission for which the rate is inversely

  18. Energy Scaling of Cold Atom-Atom-Ion Three-Body Recombination

    Science.gov (United States)

    Krükow, Artjom; Mohammadi, Amir; Härter, Arne; Denschlag, Johannes Hecker; Pérez-Ríos, Jesús; Greene, Chris H.

    2016-05-01

    We study three-body recombination of Ba++Rb +Rb in the mK regime where a single 138Ba+ ion in a Paul trap is immersed into a cloud of ultracold 87Rb atoms. We measure the energy dependence of the three-body rate coefficient k3 and compare the results to the theoretical prediction, k3∝Ecol-3 /4, where Ecol is the collision energy. We find agreement if we assume that the nonthermal ion energy distribution is determined by at least two different micromotion induced energy scales. Furthermore, using classical trajectory calculations we predict how the median binding energy of the formed molecules scales with the collision energy. Our studies give new insights into the kinetics of an ion immersed in an ultracold atom cloud and yield important prospects for atom-ion experiments targeting the s -wave regime.

  19. Energy scaling of cold atom-atom-ion three-body recombination

    CERN Document Server

    Krükow, Artjom; Härter, Arne; Denschlag, Johannes Hecker; Pérez-Ríos, Jesús; Greene, Chris H

    2015-01-01

    We study three-body recombination of Ba$^+$ + Rb + Rb in the mK regime where a single $^{138}$Ba$^{+}$ ion in a Paul trap is immersed into a cloud of ultracold $^{87}$Rb atoms. We measure the energy dependence of the three-body rate coefficient $k_3$ and compare the results to the theoretical prediction, $k_3 \\propto E_{\\textrm{col}}^{-3/4}$ where $E_{\\textrm{col}}$ is the collision energy. We find agreement if we assume that the non-thermal ion energy distribution is determined by at least two different micro-motion induced energy scales. Furthermore, using classical trajectory calculations we predict how the median binding energy of the formed molecules scales with the collision energy. Our studies give new insights into the kinetics of an ion immersed into an ultracold atom cloud and yield important prospects for atom-ion experiments targeting the s-wave regime.

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

    International Nuclear Information System (INIS)

    Highlights: ► Structural resolution of fluorite vs. pyrochlore in small nanocrystals. ► Simple template-free solvothermal synthesis of Er2O3–ZrO2 nanooxides. ► Good control over size, morphology and surface properties (280 m2 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 Er2O3–ZrO2 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 m2 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 N2 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 oriented nanocrystals

  1. The Common Elements of Atomic and Hadronic Physics

    CERN Document Server

    Brodsky, Stanley J

    2015-01-01

    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...

  2. Zeeman atomic absorption spectroscopy

    International Nuclear Information System (INIS)

    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.)

  3. 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…

  4. Spectroscopic atom symbolism

    International Nuclear Information System (INIS)

    Quantum numbers are introduced of the individual electrons of a multi-electron atom as are the concepts of electron configuration and configuration state diagram. An atom is described in Russell-Saunders approximation using the vector model concept. Overall quantum numbers are introduced for the electron shell and their relationships are discussed to the quantum numbers of the individual shell electrons. (author)

  5. 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.

  6. Multiphoton ionization of atoms

    International Nuclear Information System (INIS)

    The paper is devoted to the analysis of high intensity effects which result from multiphoton ionization of atoms in a high laser intensity, ranging from 1010 to 1015 W cm-2. Resonant multiphoton ionization of atoms, the production of multiply charged ions, and electron energy spectra, are all discussed. (U.K.)

  7. Greek Atomic Theory.

    Science.gov (United States)

    Roller, Duane H. D.

    1981-01-01

    Focusing on history of physics, which began about 600 B.C. with the Ionian Greeks and reaching full development within three centuries, suggests that the creation of the concept of the atom is understandable within the context of Greek physical theory; so is the rejection of the atomic theory by the Greek physicists. (Author/SK)

  8. Atomic Scale Plasmonic Switch.

    Science.gov (United States)

    Emboras, Alexandros; Niegemann, Jens; Ma, Ping; Haffner, Christian; Pedersen, Andreas; Luisier, Mathieu; Hafner, Christian; Schimmel, Thomas; Leuthold, Juerg

    2016-01-13

    The atom sets an ultimate scaling limit to Moore's law in the electronics industry. While electronics research already explores atomic scales devices, photonics research still deals with devices at the micrometer scale. Here we demonstrate that photonic scaling, similar to electronics, is only limited by the atom. More precisely, we introduce an electrically controlled plasmonic switch operating at the atomic scale. The switch allows for fast and reproducible switching by means of the relocation of an individual or, at most, a few atoms in a plasmonic cavity. Depending on the location of the atom either of two distinct plasmonic cavity resonance states are supported. Experimental results show reversible digital optical switching with an extinction ratio of 9.2 dB and operation at room temperature up to MHz with femtojoule (fJ) power consumption for a single switch operation. This demonstration of an integrated quantum device allowing to control photons at the atomic level opens intriguing perspectives for a fully integrated and highly scalable chip platform, a platform where optics, electronics, and memory may be controlled at the single-atom level. PMID:26670551

  9. Atomic Energy Control Board

    International Nuclear Information System (INIS)

    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

  10. Antiprotonic-hydrogen atoms

    International Nuclear Information System (INIS)

    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)

  11. 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...

  12. Moving Single Atoms

    Science.gov (United States)

    Stuart, Dustin

    2016-05-01

    Single neutral atoms are promising candidates for qubits, the fundamental unit of quantum information. We have built a set of optical tweezers for trapping and moving single Rubidium atoms. The tweezers are based on a far off-resonant dipole trapping laser focussed to a 1 μm spot with a single aspheric lens. We use a digital micromirror device (DMD) to generate dynamic holograms of the desired arrangement of traps. The DMD has a frame rate of 20 kHz which, when combined with fast algorithms, allows for rapid reconfiguration of the traps. We demonstrate trapping of up to 20 atoms in arbitrary arrangements, and the transport of a single-atom over a distance of 14 μm with continuous laser cooling, and 5 μm without. In the meantime, we are developing high-finesse fibre-tip cavities, which we plan to use to couple pairs of single atoms to form a quantum network.

  13. 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.

  14. Deconstructing Insight: EEG Correlates of Insightful Problem Solving

    OpenAIRE

    Simone Sandkühler; Joydeep Bhattacharya

    2008-01-01

    BACKGROUND: Cognitive insight phenomenon lies at the core of numerous discoveries. Behavioral research indicates four salient features of insightful problem solving: (i) mental impasse, followed by (ii) restructuring of the problem representation, which leads to (iii) a deeper understanding of the problem, and finally culminates in (iv) an "Aha!" feeling of suddenness and obviousness of the solution. However, until now no efforts have been made to investigate the neural mechanisms of these co...

  15. Atom-light interactions in quasi-1D nanostructures: a Green's function perspective

    CERN Document Server

    Asenjo-Garcia, A; Chang, D E; Kimble, H J

    2016-01-01

    Based on a formalism that describes atom-light interactions in terms of the classical electromagnetic Green's function, we study the optical response of atoms and other quantum emitters coupled to one-dimensional photonic structures, such as cavities, waveguides, and photonic crystals. We demonstrate a clear mapping between the transmission spectra and the local Green's function that allows to identify signatures of dispersive and dissipative interactions between atoms, gaining insight into recent experiments.

  16. Atomic Structure Theory Lectures on Atomic Physics

    CERN Document Server

    Johnson, Walter R

    2007-01-01

    Atomic Structure Theory is a textbook for students with a background in quantum mechanics. The text is designed to give hands-on experience with atomic structure calculations. Material covered includes angular momentum methods, the central field Schrödinger and Dirac equations, Hartree-Fock and Dirac-Hartree-Fock equations, multiplet structure, hyperfine structure, the isotope shift, dipole and multipole transitions, basic many-body perturbation theory, configuration interaction, and correlation corrections to matrix elements. Numerical methods for solving the Schrödinger and Dirac eigenvalue problems and the (Dirac)-Hartree-Fock equations are given as well. B-spline basis sets are used to carry out sums arising in higher-order many-body calculations. Illustrative problems are provided, together with solutions. FORTRAN programs implementing the numerical methods in the text are included.

  17. Linear atomic quantum coupler

    CERN Document Server

    El-Orany, Faisal A A

    2009-01-01

    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 them includes a localized and/or a trapped atom. These waveguides are placed close enough to allow exchanging energy between them via evanescent waves. Each mode interacts with the atom in the same waveguide in the standard way, i.e. as the Jaynes-Cummings model (JCM), and with the atom-mode in the second waveguide via evanescent wave. We present the Hamiltonian for the system and deduce the exact form for the wavefunction. We investigate the atomic inversions and the second-order correlation function. In contrast to the conventional linear coupler, the atomic quantum coupler is able to generate nonclassical effects. The atomic inversions can exhibit 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-m...

  18. 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.

  19. Atomic Dark Matter

    OpenAIRE

    Kaplan, David E.; Krnjaic, Gordan Z.; Rehermann, Keith R.; Wells, Christopher M.

    2009-01-01

    We propose that dark matter is dominantly comprised of atomic bound states. We build a simple model and map the parameter space that results in the early universe formation of hydrogen-like dark atoms. We find that atomic dark matter has interesting implications for cosmology as well as direct detection: Protohalo formation can be suppressed below $M_{proto} \\sim 10^3 - 10^6 M_{\\odot}$ for weak scale dark matter due to Ion-Radiation interactions in the dark sector. Moreover, weak-scale dark a...

  20. EINSTEIN, SCHROEDINGER, AND ATOM

    Directory of Open Access Journals (Sweden)

    Trunev A. P.

    2014-03-01

    Full Text Available In this paper, we consider gravitation theory in multidimensional space. The model of the metric satisfying the basic requirements of quantum theory is proposed. It is shown that gravitational waves are described by the Liouville equation and the Schrodinger equation as well. The solutions of the Einstein equations describing the stationary states of arbitrary quantum and classical systems with central symmetry have been obtained. Einstein’s atom model has been developed, and proved that atoms and atomic nuclei can be represented as standing gravitational waves

  1. 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.

  2. Single-atom nanoelectronics

    CERN Document Server

    Prati, Enrico

    2013-01-01

    Single-Atom Nanoelectronics covers the fabrication of single-atom devices and related technology, as well as the relevant electronic equipment and the intriguing new phenomena related to single-atom and single-electron effects in quantum devices. It also covers the alternative approaches related to both silicon- and carbon-based technologies, also from the point of view of large-scale industrial production. The publication provides a comprehensive picture of the state of the art at the cutting edge and constitutes a milestone in the emerging field of beyond-CMOS technology. Although there are

  3. Division of atomic physics

    International Nuclear Information System (INIS)

    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

  4. The CHIANTI atomic database

    CERN Document Server

    Young, Peter R; Landi, Enrico; Del Zanna, Giulio; Mason, Helen

    2015-01-01

    The CHIANTI atomic database was first released in 1996 and has had a huge impact on the analysis and modeling of emissions from astrophysical plasmas. The database has continued to be updated, with version 8 released in 2015. Atomic data for modeling the emissivities of 246 ions and neutrals are contained in CHIANTI, together with data for deriving the ionization fractions of all elements up to zinc. The different types of atomic data are summarized here and their formats discussed. Statistics on the impact of CHIANTI to the astrophysical community are given and examples of the diverse range of applications are presented.

  5. Inside the Hydrogen Atom

    CERN Document Server

    Nowakowski, M; Fierro, D Bedoya; Manjarres, A D Bermudez

    2016-01-01

    We apply the non-linear Euler-Heisenberg theory to calculate the electric field inside the hydrogen atom. We will demonstrate that the electric field calculated in the Euler-Heisenberg theory can be much smaller than the corresponding field emerging from the Maxwellian theory. In the hydrogen atom this happens only at very small distances. This effect reduces the large electric field inside the hydrogen atom calculated from the electromagnetic form-factors via the Maxwell equations. The energy content of the field is below the pair production threshold.

  6. Atoms, molecules, solids

    International Nuclear Information System (INIS)

    This book is an introduction to modern physics for undergraduate students of physics or students of related fields. After an introduction to the wave-particle dualism the structure of atoms is considered with regards to atomic models. Then the foundations of quantum mechanics are introduced with regards to their application to atomic structure calculations. Thereafter the chemical bond and the molecular structure are discussed. Then classical and quantum statistical mechanics are introduced. Thereafter the crystal binding, the crystal structure, and the specific heat of solids are considered. Finally the band theory of solids is briefly introduced. Every chapter contains exercise problems. (HSI)

  7. Rydberg atoms in astrophysics

    CERN Document Server

    Gnedin, Yu N; Ignjatovic, Lj M; Sakan, N M; Sreckovic, V A; Zakharov, M Yu; Bezuglov, N N; Klycharev, A N; 10.1016/j.newar.2009.07.003

    2012-01-01

    Elementary processes in astrophysical phenomena traditionally attract researchers attention. At first this can be attributed to a group of hemi-ionization processes in Rydberg atom collisions with ground state parent atoms. This processes might be studied as a prototype of the elementary process of the radiation energy transformation into electrical one. The studies of nonlinear mechanics have shown that so called regime of dynamic chaos should be considered as typical, rather than exceptional situation in Rydberg atoms collision. From comparison of theory with experimental results it follows that a such kind of stochastic dynamic processes, occurred during the single collision, may be observed.

  8. 78 FR 58571 - Maine Yankee Atomic Power Company, Connecticut Yankee Atomic Power Company, and The Yankee Atomic...

    Science.gov (United States)

    2013-09-24

    ... Atomic Power Company, Connecticut Yankee Atomic Power Company, and The Yankee Atomic Electric Company... Power Company (Maine Yankee), Connecticut Yankee Atomic Power Company (Connecticut Yankee), and the Yankee Atomic Electric Company (Yankee Atomic) (together, ``licensees'' or ``the Yankee Companies'')...

  9. 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.

  10. Atomic and Molecular Interactions

    International Nuclear Information System (INIS)

    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

  11. Atomic bomb cataracts

    International Nuclear Information System (INIS)

    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.)

  12. Atomic Interferometry Project

    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...

  13. The Atomic Dating Game.

    Science.gov (United States)

    Cummo, Evelyn; Matthews, Catherine E.

    2002-01-01

    Presents an activity designed to provide students with opportunities to practice drawing atomic models and discover the logical pairings of whole families on the periodic table. Follows the format of a television game show. (DDR)

  14. The CHIANTI atomic database

    Science.gov (United States)

    Young, P. R.; Dere, K. P.; Landi, E.; Del Zanna, G.; Mason, H. E.

    2016-04-01

    The freely available CHIANTI atomic database was first released in 1996 and has had a huge impact on the analysis and modeling of emissions from astrophysical plasmas. It contains data and software for modeling optically thin atom and positive ion emission from low density (≲1013 cm-3) plasmas from x-ray to infrared wavelengths. A key feature is that the data are assessed and regularly updated, with version 8 released in 2015. Atomic data for modeling the emissivities of 246 ions and neutrals are contained in CHIANTI, together with data for deriving the ionization fractions of all elements up to zinc. The different types of atomic data are summarized here and their formats discussed. Statistics on the impact of CHIANTI to the astrophysical community are given and examples of the diverse range of applications are presented.

  15. 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

  16. Conceptual atomism rethought.

    Science.gov (United States)

    Schneider, Susan

    2010-06-01

    Focusing on Machery's claim that concepts play entirely different roles in philosophy and psychology, I explain how one well-known philosophical theory of concepts, Conceptual Atomism (CA), when properly understood, takes into account both kinds of roles. PMID:20584416

  17. 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...

  18. Improved Atomizer Resists Clogging

    Science.gov (United States)

    Dea, J. Y.

    1983-01-01

    Improved constant-output atomizer has conical orifice that permits air to sweep out all liquid thoroughly and prevent any buildup of liquid or dissolved solids. Capillary groove guides liquid to gas jet. Simple new design eliminates clogging.

  19. Zeeman atomic absorption spectrometry

    International Nuclear Information System (INIS)

    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

  20. Atomic Energy Act 1946

    International Nuclear Information System (INIS)

    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)

  1. Dangerous Energy : Atomic

    International Nuclear Information System (INIS)

    This book describes the disaster in Chernobyl, Russia. Through the accident It reveals the dangerous nuclear energy with a lot of problems on the nuclear power plants which includes four reasons about propelling development of atomic and criticism about that, eight reasons against development of atomic, the problem in 11 -12 nuclear power plant, the movement of antagonism towards nuclear waste in Anmyon island, cases of antinuclear in foreign country and building of new energy system.

  2. Atom laser divergence

    OpenAIRE

    Le Coq, Yann; Thywissen, Joseph H.; Rangwala, Sadiq A.; Gerbier, Fabrice; Richard, Simon; Delannoy, Guillaume; Bouyer, Philippe; Aspect, Alain

    2001-01-01

    We measure the angular divergence of a quasi-continuous, rf-outcoupled, free-falling atom laser as a function of the outcoupling frequency. The data is compared to a Gaussian-beam model of laser propagation that generalizes the standard formalism of photonic lasers. Our treatment includes diffraction, magnetic lensing, and interaction between the atom laser and the condensate. We find that the dominant source of divergence is the condensate-laser interaction.

  3. Guided Quasicontinuous Atom Laser

    OpenAIRE

    Guerin, William; Riou, Jean-Félix; Gaebler, John,; Josse, Vincent; Bouyer, Philippe; Aspect, Alain

    2006-01-01

    version published in Phys. Rev. Lett. 97, 200402 (2006) International audience We report the first realization of a guided quasicontinuous atom laser by rf outcoupling a Bose-Einstein condensate from a hybrid optomagnetic trap into a horizontal atomic waveguide. This configuration allows us to cancel the acceleration due to gravity and keep the de Broglie wavelength constant at 0.5 µm during 0.1 s of propagation. We also show that our configuration, equivalent to pigtailing an optical f...

  4. Metal atomization spray nozzle

    Science.gov (United States)

    Huxford, Theodore J.

    1993-01-01

    A spray nozzle for a magnetohydrodynamic atomization apparatus has a feed passage for molten metal and a pair of spray electrodes mounted in the feed passage. The electrodes, diverging surfaces which define a nozzle throat and diverge at an acute angle from the throat. Current passes through molten metal when fed through the throat which creates the Lorentz force necessary to provide atomization of the molten metal.

  5. 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.

  6. Atomic Bomb Health Benefits

    OpenAIRE

    Luckey, T.D.

    2008-01-01

    Media reports of deaths and devastation produced by atomic bombs convinced people around the world that all ionizing radiation is harmful. This concentrated attention on fear of miniscule doses of radiation. Soon the linear no threshold (LNT) paradigm was converted into laws. Scientifically valid information about the health benefits from low dose irradiation was ignored. Here are studies which show increased health in Japanese survivors of atomic bombs. Parameters include decreased mutation,...

  7. Structure and Dynamics of Glycosphingolipids in Lipid Bilayers: Insights from Molecular Dynamics Simulations

    Directory of Open Access Journals (Sweden)

    Ronak Y. Patel

    2011-01-01

    Full Text Available Glycolipids are important constituents of biological membranes, and understanding their structure and dynamics in lipid bilayers provides insights into their physiological and pathological roles. Experimental techniques have provided details into their behavior at model and biological membranes; however, computer simulations are needed to gain atomic level insights. This paper summarizes the insights obtained from MD simulations into the conformational and orientational dynamics of glycosphingolipids and their exposure, hydration, and hydrogen-bonding interactions in membrane environment. The organization of glycosphingolipids in raft-like membranes and their modulation of lipid membrane structure are also reviewed.

  8. Atomic bomb and leukemia

    International Nuclear Information System (INIS)

    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)

  9. Theoretical atomic collision physics

    Energy Technology Data Exchange (ETDEWEB)

    Lane, N.F. (Rice Univ., Houston, TX (USA) Rice Univ., Houston, TX (USA). Quantum Inst.)

    1990-01-01

    The theoretical atomic physics at Rice University focuses on obtaining a better understanding of the mechanisms that control inelastic collisions between excited atoms and atoms, molecules and ions. Particular attention is given to systems and processes that are of potential importance to advanced energy technologies. In the current year, significant progress has been made in quantitative studies of: quenching of low-Rydberg Na atoms in thermal energy collisions with He, Ne and Ar atoms; selective excitation resulting from charge transfer in collisions of highly stripped ions of He, Li, C, and with Li, Na and He atoms and H{sub 2} molecules at keV energies; differential elastic and single, and double electron transfer in He{sup ++} collisions with He at keV energies; inelastic electron-transfer in ultra-low-energy-energy (T=8 to 80K) collisions between {sup 3}He{sup +} and {sup 4}He and {sup 4}He{sup +} and {sup 3}He; a formalism for ionization by electron impact of ions in dense, high temperature plasmas.

  10. 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.

  11. Atomic phenomena in dense plasmas

    International Nuclear Information System (INIS)

    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

  12. Energy levels of light atoms in strong magnetic fields

    CERN Document Server

    Thirumalai, Anand

    2014-01-01

    In this review article we provide an overview of the field of atomic structure of light atoms in strong magnetic fields. There is a very rich history of this field which dates back to the very birth of quantum mechanics. At various points in the past significant discoveries in science and technology have repeatedly served to rejuvenate interest in atomic structure in strong fields, broadly speaking, resulting in three eras in the development of this field; the historical, the classical and the modern eras. The motivations for studying atomic structure have also changed significantly as time progressed. The review presents a chronological summary of the major advances that occurred during these eras and discusses new insights and impetus gained. The review is concluded with a description of the latest findings and the future prospects for one of the most remarkably cutting-edge fields of research in science today.

  13. Deconstructing insight: EEG correlates of insightful problem solving.

    Directory of Open Access Journals (Sweden)

    Simone Sandkühler

    Full Text Available BACKGROUND: Cognitive insight phenomenon lies at the core of numerous discoveries. Behavioral research indicates four salient features of insightful problem solving: (i mental impasse, followed by (ii restructuring of the problem representation, which leads to (iii a deeper understanding of the problem, and finally culminates in (iv an "Aha!" feeling of suddenness and obviousness of the solution. However, until now no efforts have been made to investigate the neural mechanisms of these constituent features of insight in a unified framework. METHODOLOGY/PRINCIPAL FINDINGS: In an electroencephalographic study using verbal remote associate problems, we identified neural correlates of these four features of insightful problem solving. Hints were provided for unsolved problems or after mental impasse. Subjective ratings of the restructuring process and the feeling of suddenness were obtained on trial-by-trial basis. A negative correlation was found between these two ratings indicating that sudden insightful solutions, where restructuring is a key feature, involve automatic, subconscious recombination of information. Electroencephalogram signals were analyzed in the space x time x frequency domain with a nonparametric cluster randomization test. First, we found strong gamma band responses at parieto-occipital regions which we interpreted as (i an adjustment of selective attention (leading to a mental impasse or to a correct solution depending on the gamma band power level and (ii encoding and retrieval processes for the emergence of spontaneous new solutions. Secondly, we observed an increased upper alpha band response in right temporal regions (suggesting active suppression of weakly activated solution relevant information for initially unsuccessful trials that after hint presentation led to a correct solution. Finally, for trials with high restructuring, decreased alpha power (suggesting greater cortical excitation was observed in right prefrontal

  14. Effective potentials for atom-atom interaction at low temperatures

    OpenAIRE

    Gao, Bo

    2002-01-01

    We discuss the concept and design of effective atom-atom potentials that accurately describe any physical processes involving only states around the threshold. The existence of such potentials gives hope to a quantitative, and systematic, understanding of quantum few-atom and quantum many-atom systems at relatively low temperatures.

  15. Single-atom spintronics

    Institute of Scientific and Technical Information of China (English)

    Susan Z. HUA; Matthew R. SULLIVAN; Jason N. ARMSTRONG

    2006-01-01

    Recent work on magnetic quantum point contacts (QPCs) was discussed. Complete magnetoresistance loops across Co QPCs as small as a single atom was measured. The remarkable feature of these QPCs is the rapid oscillatory decay in magnetoresistance with the increase of contact size. In addition,stepwise or quantum magnetoresistance loops are observed,resulting from varying transmission probability of the available discrete conductance channels because the sample is cycled between the ferromagnetic (F) and antiferromagnetic (AF) aligned states. Quantized conductance combined with spin dependent transmission of electron waves gives rise to a multi-channel system with a quantum domain wall acting as a valve,i.e.,a quantum spin-valve. Behavior of a few-atom QPC is built on the behavior of a single-atom QPC and hence the summarization of results as 'single-atom spintronics'. An evolutionary trace of spin-dependent electron transmission from a single atom to bulk is provided,the requisite hallmarks of artefact-free magnetoresistance is established across a QPC - stepwise or quantum magnetoresistance loops and size dependent oscillatory magnetoresistance.

  16. Understanding Insight in the Context of Q

    Science.gov (United States)

    Coghlan, David

    2012-01-01

    In Revans' learning formula, L = P + Q, Q represents "questioning insight", by which Revans means that insight comes out of the process of questioning programmed knowledge (P) in the light of experience. We typically focus on the content of an insight rather than on the act of insight. Drawing primarily on the work of Bernard Lonergan this paper…

  17. Universal bosonic tetramers of dimer-atom-atom structure

    OpenAIRE

    Deltuva, A.

    2012-01-01

    Unstable four-boson states having an approximate dimer-atom-atom structure are studied using momentum-space integral equations for the four-particle transition operators. For a given Efimov trimer the universal properties of the lowest associated tetramer are determined. The impact of this tetramer on the atom-trimer and dimer-dimer collisions is analyzed. The reliability of the three-body dimer-atom-atom model is studied.

  18. Multiphoton ionization of atoms

    International Nuclear Information System (INIS)

    This article provides an overview of the current understanding of multiphoton ionization of atoms. It begins with an introductory section to explain the background of the subject. Then the article develops the three topics which have been central themes of discussion in multiphoton ionization of atoms these past few years: multiply charged ion production, very high order harmonic generation, and above-threshold ionization, a name given to the absorption of a very large number of photons by an already ionized electron. A large part of the review is devoted to some theoretical aspects of multiphoton ionization of atoms and especially non-perturbative theories. Finally the article considers the very near future prospects of laser-electron interactions and more generally laser-matter interactions at 1018 -1019 W cm-2, an intensity range now within reach due to new short pulse laser technology. (author)

  19. Atom Probe Tomography

    International Nuclear Information System (INIS)

    Atom probe tomography (APT) is a lens-less point-projection microscopy that resolves individual atoms on the surface of a sharply pointed tip (radius of curvature R < 100 nm), at a magnification of the order of ⁓106. The specimen tip is pulsed to a positive potential V with respect to ground, thereby generating electric fields E ⁓ V/R of some 10 V/nm. Ions released from the apex due to field evaporation are sent flying to a position sensitive detector where they are identified by time-of-flight mass spectrometry. Continuous removal of single atoms provides the possibility of a 3D elemental characterization of solids with sub-nm spatial resolution. The basic principles of the technique and some selected analytical applications will be discussed. (author)

  20. Electron-atom collisions

    International Nuclear Information System (INIS)

    This book is a comprehensive introduction to electron-atom collisions, covering both theory and experiment. The interaction of electrons with atoms is the field that most deeply probes both the structure and reaction dynamics of a many-body system. The book begins with a short account of experimental techniques of cross-section measurement. It then introduces the essential quantum mechanics background needed. The following chapters cover one-electron problems (from the classic particle in a box to a relativistic electron in a central potential), the theory of atomic bound states, formal scattering theory, calculation of scattering amplitudes, spin-independent and spin-dependent scattering observables, ionisation and electron momentum spectroscopy. The connections between experimental and theoretical developments are emphasised throughout. (author)

  1. Atomic profits, no thanks

    International Nuclear Information System (INIS)

    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)

  2. Sampling the Hydrogen Atom

    Directory of Open Access Journals (Sweden)

    Graves N.

    2013-01-01

    Full Text Available A model is proposed for the hydrogen atom in which the electron is an objectively real particle orbiting at very near to light speed. The model is based on the postulate that certain velocity terms associated with orbiting bodies can be considered as being af- fected by relativity. This leads to a model for the atom in which the stable electron orbits are associated with orbital velocities where Gamma is n /α , leading to the idea that it is Gamma that is quantized and not angular momentum as in the Bohr and other models. The model provides a mechanism which leads to quantization of energy levels within the atom and also provides a simple mechanical explanation for the Fine Struc- ture Constant. The mechanism is closely associated with the Sampling theorem and the related phenomenon of aliasing developed in the mid-20th century by engineers at Bell labs.

  3. Accelerators for atomic energy research

    International Nuclear Information System (INIS)

    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)

  4. Quantum magnetism through atomic assembly

    NARCIS (Netherlands)

    Spinelli, A.

    2015-01-01

    This thesis presents an experimental study of magnetic structures, composed of only a few atoms. Those structures are first built atom-by-atom and then locally probed, both with a low-temperature STM. The technique that we use to assemble them is vertical atom manipulation, while to study their phy

  5. Atoms in Slovakia

    International Nuclear Information System (INIS)

    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 20th 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'

  6. Hydrogen negative ions and collisions of atomic particles

    International Nuclear Information System (INIS)

    This paper will be an overview presenting some of the basic atomic collisions processes (gas phase) which are fundamental to production and destruction of H-(D-). More detailed discussions of the most important processes will be left to other papers at this Symposium, and primarily new results since the 1977 Symposium will be discussed. Recent results provide insight into mechanisms responsible for the high H-(D-) ion fractions in hydrogen gas discharges, and the ion-atom collision processes important for double capture negative ion sources are better understood than in 1977

  7. Tuning the surface chemistry of Pd by atomic C and H: a microscopic picture.

    Science.gov (United States)

    Aleksandrov, Hristiyan A; Viñes, Francesc; Ludwig, Wiebke; Schauermann, Swetlana; Neyman, Konstantin M

    2013-01-21

    Palladium is crucial for industry-related applications such as heterogeneous catalysis, energy production, and hydrogen technologies. In many processes, atomic H and C species are proposed to be present in the surface/near-surface area of Pd, thus noticeably affecting its chemical activity. This study provides a detail and unified view on the interactions of the H and C species with Pd nanoparticles (NPs), which is indispensable for insight into their catalytic properties. Density functional calculations of the interplay of C and H atoms at various concentrations and sites on suitable Pd NPs have been performed, accompanied by catalysis-relevant experiments on oxide-supported bare and C-modified Pd NPs. It is shown that on a Pd(79) NP a subsurface C atom destabilizes nearby atoms H at low coverage. Our experiments confirm that H atoms bind more weakly on C-containing Pd NPs than on C-free NPs. Various factors related to the presence of both H and C atoms on a Pd(79) surface, which may influence the penetration of H atoms from the surface into the subsurface area, have been investigated. Carbon atoms facilitate the subsurface penetration of atomic H both thermodynamically and kinetically when the surface is densely covered by H atoms. Moreover, subsurface H atoms are also energetically favored, even in the absence of C atoms, when several facets of the NP are covered by H atoms. PMID:23180515

  8. Polarized atomic hydrogen beam

    Energy Technology Data Exchange (ETDEWEB)

    Chan, N.; Crowe, D.M.; Lubell, M.S.; Tang, F.C.; Vasilakis, A.; Mulligan, F.J.; Slevin, J.

    1988-12-01

    We describe the design and operating characteristics of a simple polarized atomic hydrogen beam particularly suitable for applications to crossed beams experiments. In addition to experimental measurements, we present the results of detailed computer models, using Monte-Carlo ray tracing techniques, optical analogs, and phase-space methods, that not only provide us with a confirmation of our measurement, but also allow us to characterize the density, polarization, and atomic fraction of the beam at all points along its path. As a subsidiary result, we also present measurements of the relative and absolute efficiencies of the V/G Supavac mass analyzer for masses 1 and 2.

  9. Korean atomic bomb victims.

    Science.gov (United States)

    Sasamoto, Yukuo

    2009-01-01

    After colonizing Korea, Japan invaded China, and subsequently initiated the Pacific War against the United States, Britain, and their allies. Towards the end of the war, U.S. warplanes dropped atomic bombs on Hiroshima and Nagasaki, which resulted in a large number of Koreans who lived in Hiroshima and Nagasaki suffering from the effects of the bombs. The objective of this paper is to examine the history of Korea atomic bomb victims who were caught in between the U.S., Japan, the Republic of Korea (South Korea) and the Democratic People's Republic of Korea (North Korea). PMID:20521424

  10. 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

  11. D^- mesic atoms

    OpenAIRE

    García Recio, Carmen; Nieves Pamplona, Juan Miguel; Salcedo, Lorenzo Luis; Tolós Rigueiro, Laura

    2011-01-01

    The anti-D meson self-energy is evaluated self-consistently, using unitarized coupled-channel theory, by computing the in-medium meson-baryon T-matrix in the C=-1,S=0 sector. The heavy pseudo-scalar and heavy vector mesons, anti-D and anti-D^*, are treated on equal footing as required by heavy quark spin symmetry. Results for energy levels and widths of D^- mesic atoms in 12C, 40Ca, 118Sn and 208Pb are presented. The spectrum contains states of atomic and of nuclear types for all nuclei. anti...

  12. Atoms in Agriculture

    Energy Technology Data Exchange (ETDEWEB)

    Osborne, Thomas S. [University of Tennessee

    1965-01-01

    Agriculture benefits from the applications of research. Radioactive techniques have been used to study soils, plants, microbes, insects, farm animals, and new ways to use and preserve foodstuffs. Radioactive atoms are not used directly by farmers but are used in research directed by the U. S. Department of Agriculture and Atomic Energy Commission, by the agricultural experiment stations of the various states, and by numerous public and private research institutions. From such research come improved materials and methods which are used on the farm.

  13. 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.

  14. Polarized atomic beams for targets

    International Nuclear Information System (INIS)

    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

  15. Atomic structure and surface defects at mineral-water interfaces probed by in situ atomic force microscopy

    Science.gov (United States)

    Siretanu, Igor; van den Ende, Dirk; Mugele, Frieder

    2016-04-01

    Atomic scale details of surface structure play a crucial role for solid-liquid interfaces. While macroscopic characterization techniques provide averaged information about bulk and interfaces, high resolution real space imaging reveals unique insights into the role of defects that are believed to dominate many aspects of surface chemistry and physics. Here, we use high resolution dynamic Atomic Force Microscopy (AFM) to visualize and characterize in ambient water the morphology and atomic scale structure of a variety of nanoparticles of common clay minerals adsorbed to flat solid surfaces. Atomically resolved images of the (001) basal planes are obtained on all materials investigated, namely gibbsite, kaolinite, illite, and Na-montmorillonite of both natural and synthetic origin. Next to regions of perfect crystallinity, we routinely observe extended regions of various types of defects on the surfaces, including vacancies of one or few atoms, vacancy islands, atomic steps, apparently disordered regions, as well as strongly adsorbed seemingly organic and inorganic species. While their exact nature is frequently difficult to identify, our observations clearly highlight the ubiquity of such defects and their relevance for the overall physical and chemical properties of clay nanoparticle-water interfaces.Atomic scale details of surface structure play a crucial role for solid-liquid interfaces. While macroscopic characterization techniques provide averaged information about bulk and interfaces, high resolution real space imaging reveals unique insights into the role of defects that are believed to dominate many aspects of surface chemistry and physics. Here, we use high resolution dynamic Atomic Force Microscopy (AFM) to visualize and characterize in ambient water the morphology and atomic scale structure of a variety of nanoparticles of common clay minerals adsorbed to flat solid surfaces. Atomically resolved images of the (001) basal planes are obtained on all

  16. Atomic collisions, inelastic indeed

    Science.gov (United States)

    Bercegol, Herve; Ferrando, Gwenael; Lehoucq, Roland

    At the turn of the twentieth century, a hot controversy raged about the ability of Boltzmann's framework to take care of irreversibility. The so-called Loschmidt's paradox progressively faded with time during the last hundred years, due to the predictive efficiency of statistical mechanics. However, one detail at the origin of the controversy - the elasticity of atomic collisions - was not completely challenged. A semi-classical treatment of two atoms interacting with the vacuum zero-point field permits to predict a friction force acting against the rotation of the pair of atoms. By its form and its level, the calculated torque is a candidate as a physical cause for diffusion of energy and angular momentum, and consequently for entropy growth. It opens the way to a revision of the standard vision of irreversibility. This presentation will focus on two points. First we will discuss the recent result in a broader context of electromagnetic interactions during microscopic collisions. The predicted friction phenomenon can be compared to and distinguished from Collision-Induced Emission and other types of inelastic collisions. Second we will investigate the consequences of the friction torque on calculated trajectories of colliding atoms, quantifying the generation of dimers linked by dispersion forces.

  17. Experimental atomic physics

    International Nuclear Information System (INIS)

    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

  18. Ludwig Boltzmann: Atomic genius

    International Nuclear Information System (INIS)

    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.)

  19. Atomism, Pragmatism, Holism.

    Science.gov (United States)

    Miller, John P.

    1986-01-01

    Examines three world views influencing curriculum development--atomism (underpinning competency-based education), pragmatism (promoting inquiry-based approaches), amd holism (associated with confluent or Waldorf education). Holism embodies the perennial philosophy and attempts to integrate cognitive, affective, and transpersonal dimensions,…

  20. Spectra of alkali atoms

    International Nuclear Information System (INIS)

    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.)

  1. Atomic Energy Authority Bill

    International Nuclear Information System (INIS)

    On the third reading of the Atomic Energy Authority Bill the following matters were discussed: safety research and thermal reactor work - how funded when the Authority is operating on trading fund basis; future financial framework of the Authority; capital investment; loans; effect of change on Authority employees. (U.K.)

  2. Transition probabilities for atoms

    International Nuclear Information System (INIS)

    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

  3. Atomic physics and reality

    CERN Multimedia

    1985-01-01

    An account of the long standing debate between Niels Bohr and Albert Einstein regarding the validity of the quantum mechanical description of atomic phenomena.With physicts, John Wheeler (Texas), John Bell (CERN), David Rohm (London), Abner Shimony (Boston), Alain Aspect (Paris)

  4. 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.

  5. Bonds Between Atoms.

    Science.gov (United States)

    Holden, Alan

    The field of inquiry into how atoms are bonded together to form molecules and solids crosses the borderlines between physics and chemistry encompassing methods characteristic of both sciences. At one extreme, the inquiry is pursued with care and rigor into the simplest cases; at the other extreme, suggestions derived from the more careful inquiry…

  6. Atomic transport properties

    International Nuclear Information System (INIS)

    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)

  7. Atomic spectrum of neptunium

    International Nuclear Information System (INIS)

    A description and interpretation of the atomic spectrum of neptunium are given. Wavelengths were measured for 6096 spectrum lines in the range 3793 to 38,812 cm-1 (26,353 to 2575 A), of which 2526 were classified as transitions between 329 odd levels and 130 even levels of neutral neptunium (Np I). The data are presented in five tables

  8. Nonperturbative and perturbative treatments of parametric heating in atom traps

    CERN Document Server

    Jauregui, R

    2001-01-01

    We study the quantum description of parametric heating in harmonic potentials both nonperturbatively and perturbatively, having in mind atom traps. The first approach establishes an explicit connection between classical and quantum descriptions; it also gives analytic expressions for properties such as the width of fractional frequency parametric resonances. The second approach gives an alternative insight into the problem and can be directly extended to take into account nonlinear effects. This is specially important for shallow traps.

  9. Nonperturbative and perturbative treatments of parametric heating in atom traps

    OpenAIRE

    Jauregui, R.

    2001-01-01

    We study the quantum description of parametric heating in harmonic potentials both nonperturbatively and perturbatively, having in mind atom traps. The first approach establishes an explicit connection between classical and quantum descriptions; it also gives analytic expressions for properties such as the width of fractional frequency parametric resonances. The second approach gives an alternative insight into the problem and can be directly extended to take into account nonlinear effects. T...

  10. Precision atomic physics techniques for nuclear physics with radioactive beams

    OpenAIRE

    Blaum, Klaus; Dilling, Jens; Nörtershäuser, Wilfried

    2013-01-01

    Atomic physics techniques for the determination of ground-state properties of radioactive isotopes are very sensitive and provide accurate masses, binding energies, Q-values, charge radii, spins, and electromagnetic moments. Many fields in nuclear physics benefit from these highly accurate numbers. They give insight into details of the nuclear structure for a better understanding of the underlying effective interactions, provide important input for studies of fundamental symmetries in physics...

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

    International Nuclear Information System (INIS)

    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

  12. Atomic clocks: the atoms as primary time and frequency standards

    International Nuclear Information System (INIS)

    In this article, we present the atomic clock as time and frequency standard and as one of the peaceful uses of atoms for development. In the first part, we present the general principles of time and frequency metrology and the key role of the caesium atom in this field as well as the main applications of atomic clocks. In the second part we introduce the different clock technologies based on Ramsey method, with a focus on atomic beam clocks and atomic fountain clocks. (author)

  13. Stanene: Atomically Thick Free-standing Layer of 2D Hexagonal Tin.

    Science.gov (United States)

    Saxena, Sumit; Chaudhary, Raghvendra Pratap; Shukla, Shobha

    2016-01-01

    Stanene is one of most important of 2D materials due to its potential to demonstrate room temperature topological effects due to opening of spin-orbit gap. In this pursuit we report synthesis and investigation of optical properties of stanene up to few layers, a two-dimensional hexagonal structural analogue of graphene. Atomic scale morphological and elemental characterization using HRTEM equipped with SAED and EDAX detectors confirm the presence of hexagonal lattice of Sn atoms. The position of Raman peak along with the inter-planar 'd' spacing obtained from SAED for prepared samples are in good agreement with that obtained from first principles calculations and confirm that the sheets are not (111) α-Sn sheets. Further, the optical signature calculated using density functional theory at ~191 nm and ~233 nm for low buckled stanene are in qualitative agreement with the measured UV-Vis absorption spectrum. AFM measurements suggest interlayer spacing of ~0.33 nm in good agreement with that reported for epitaxial stanene sheets. No traces of oxygen were observed in the EDAX spectrum suggesting the absence of any oxidized phases. This is also confirmed by Raman measurements by comparing with oxidized stanene sheets. PMID:27492139

  14. 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

  15. Versatile compact atomic source for high resolution dual atom interferometry

    CERN Document Server

    Müller, T; Gilowski, M; Jentsch, C; Rasel, E M; Ertmer, W

    2007-01-01

    We present a compact $^{87}$Rb atomic source for high precision dual atom interferometers. The source is based on a double-stage magneto-optical trap (MOT) design, consisting of a 2-dimensional (2D)-MOT for efficient loading of a 3D-MOT. The accumulated atoms are precisely launched in a horizontal moving molasses. Our setup generates a high atomic flux ($>10^{10}$ atoms/s) with precise and flexibly tunable atomic trajectories as required for high resolution Sagnac atom interferometry. We characterize the performance of the source with respect to the relevant parameters of the launched atoms, i.e. temperature, absolute velocity and pointing, by utilizing time-of-flight techniques and velocity selective Raman transitions.

  16. Atom inlays performed at room temperature using atomic force microscopy

    Science.gov (United States)

    Sugimoto, Yoshiaki; Abe, Masayuki; Hirayama, Shinji; Oyabu, Noriaki; Custance, Óscar; Morita, Seizo

    2005-02-01

    The ability to manipulate single atoms and molecules laterally for creating artificial structures on surfaces is driving us closer to the ultimate limit of two-dimensional nanoengineering. However, experiments involving this level of manipulation have been performed only at cryogenic temperatures. Scanning tunnelling microscopy has proved, so far, to be a unique tool with all the necessary capabilities for laterally pushing, pulling or sliding single atoms and molecules, and arranging them on a surface at will. Here we demonstrate, for the first time, that it is possible to perform well-controlled lateral manipulations of single atoms using near-contact atomic force microscopy even at room temperature. We report the creation of 'atom inlays', that is, artificial atomic patterns formed from a few embedded atoms in the plane of a surface. At room temperature, such atomic structures remain stable on the surface for relatively long periods of time.

  17. Rydberg atom ionization by slow collisions with alkali element atoms

    International Nuclear Information System (INIS)

    A new mechanism for ionization of highexcited atoms due to the electron capture into the autoionization state of a negative ion is suggested. Calculations of cross-sections and the ionization rate for sodium and lithium atoms collisions are performed

  18. Microtraps and Atom Chips: Toolboxes for Cold Atom Physics

    OpenAIRE

    Feenstra, L.; Andersson, L. M.; Schmiedmayer, J.

    2003-01-01

    Magnetic microtraps and Atom Chips are safe, small-scale, reliable and flexible tools to prepare ultra-cold and degenerate atom clouds as sources for various atom-optical experiments. We present an overview of the possibilities of the devices and indicate how a microtrap can be used to prepare and launch a Bose-Einstein condensate for use in an atom clock or an interferometer.

  19. Dynamics of atom-atom correlations in the Fermi problem

    OpenAIRE

    Borrelli, Massimo; Sabín, Carlos; Adesso, Gerardo; Plastina, Francesco; Maniscalco, Sabrina

    2012-01-01

    We present a detailed perturbative study of the dynamics of several types of atom-atom correlations in the famous Fermi problem. This is an archetypal model to study micro-causality in the quantum domain, where two atoms, one initially excited and the other prepared in its ground state, interact with the vacuum electromagnetic field. The excitation can be transferred to the second atom via a flying photon, and various kinds of quantum correlations between the two are generated during this pro...

  20. Atomic Coherent Trapping and Properties of Trapped Atom

    Institute of Scientific and Technical Information of China (English)

    YANG Guo-Jian; XIA Li-Xin; XIE Min

    2006-01-01

    Based on the theory of velocity-selective coherent population trapping, we investigate an atom-laser system where a pair of counterpropagating laser fields interact with a three-level atom. The influence of the parametric condition on the properties of the system such as velocity at which the atom is selected to be trapped, time needed for finishing the coherent trapping process, and possible electromagnetically induced transparency of an altrocold atomic medium,etc., is studied.

  1. Meteorology and atomic energy

    International Nuclear Information System (INIS)

    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

  2. Optical atomic clocks

    International Nuclear Information System (INIS)

    In the last ten years extraordinary results in time and frequency metrology have been demonstrated. Frequency-stabilization techniques for continuous-wave lasers and femtosecond optical frequency combs have enabled a rapid development of frequency standards based on optical transitions in ultra-cold neutral atoms and trapped ions. As a result, today’s best performing atomic clocks tick at an optical rate and allow scientists to perform high-resolution measurements with a precision approaching a few parts in 1018. This paper reviews the history and the state of the art in optical-clock research and addresses the implementation of optical clocks in a possible future redefinition of the SI second as well as in tests of fundamental physics.

  3. D- mesic atoms

    Science.gov (United States)

    García-Recio, C.; Nieves, J.; Salcedo, L. L.; Tolos, L.

    2012-02-01

    The anti-D meson self-energy is evaluated self-consistently, using unitarized coupled-channel theory, by computing the in-medium meson-baryon T matrix in the C=-1,S=0 sector. The heavy pseudo-scalar and heavy vector mesons, D¯ and D¯*, are treated on equal footing as required by heavy-quark spin symmetry. Results for energy levels and widths of D- mesic atoms in 12C, 40Ca, 118Sn, and 208Pb are presented. The spectrum contains states of atomic and of nuclear types for all nuclei. D¯0-nucleus bound states are also obtained. We find that, after electromagnetic and nuclear cascade, these systems end up with the D¯ bound in the nucleus, either as a meson or as part of an exotic D¯N (pentaquark) loosely bound state.

  4. Optical atomic clocks

    CERN Document Server

    Poli, N; Gill, P; Tino, G M

    2014-01-01

    In the last ten years extraordinary results in time and frequency metrology have been demonstrated. Frequency-stabilization techniques for continuous-wave lasers and femto-second optical frequency combs have enabled a rapid development of frequency standards based on optical transitions in ultra-cold neutral atoms and trapped ions. As a result, today's best performing atomic clocks tick at an optical rate and allow scientists to perform high-resolution measurements with a precision approaching a few parts in $10^{18}$. This paper reviews the history and the state of the art in optical-clock research and addresses the implementation of optical clocks in a possible future redefinition of the SI second as well as in tests of fundamental physics.

  5. Optical atomic clocks

    Science.gov (United States)

    Poli, N.; Oates, C. W.; Gill, P.; Tino, G. M.

    2013-12-01

    In the last ten years extraordinary results in time and frequency metrology have been demonstrated. Frequency-stabilization techniques for continuous-wave lasers and femtosecond optical frequency combs have enabled a rapid development of frequency standards based on optical transitions in ultra-cold neutral atoms and trapped ions. As a result, today's best performing atomic clocks tick at an optical rate and allow scientists to perform high-resolution measurements with a precision approaching a few parts in 1018. This paper reviews the history and the state of the art in optical-clock research and addresses the implementation of optical clocks in a possible future redefinition of the SI second as well as in tests of fundamental physics.

  6. Rydberg atom in gravity

    International Nuclear Information System (INIS)

    The local position invariance of a physical system is examined using a Rydberg atom and the universality of free fall is found to be invalid for a quantum system. A Rydberg atom is analysed in Newtonian gravity and curved space. The energy is found to vary as n2 for very large values of the principal quantum number n. The change in energy is calculated using this formalism and compared to a similar calculation by Chiao. The value that we have got from our calculation is found to be 6 orders higher in magnitude than Chiao's value. These results can be of significance in gravitational redshift experiements proposed by Muller et al and Wolf et al

  7. Interfacing ultracold atoms and mechanical oscillators on an atom chip

    Science.gov (United States)

    Treutlein, Philipp

    2010-03-01

    Ultracold atoms can be trapped and coherently manipulated close to a chip surface using atom chip technology. This opens the exciting possibility of studying interactions between atoms and on-chip solid-state systems such as micro- and nanostructured mechanical oscillators. One goal is to form hybrid quantum systems, in which atoms are used to read out, cool, and coherently manipulate the oscillators' state. In our work, we investigate different coupling mechanisms between ultracold atoms and mechanical oscillators. In a first experiment, we use atom-surface forces to couple the vibrations of a mechanical cantilever to the motion of a Bose-Einstein condensate in a magnetic microtrap on an atom chip. The atoms are trapped at about one micrometer distance from the cantilever surface. We make use of the coupling to read out the cantilever vibrations with the atoms and observe resonant coupling to several well-resolved mechanical modes of the condensate. In a second experiment, we investigate coupling via a 1D optical lattice that is formed by a laser beam retroreflected from a SiN membrane oscillator. The optical lattice serves as a `transfer rod' that couples vibrations of the membrane to the atoms and vice versa. We point out that the strong coupling regime can be reached in coupled atom-oscillator systems by placing both the atoms and the oscillator in a high-finesse optical cavity.

  8. Glossary of atomic terms

    International Nuclear Information System (INIS)

    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)

  9. Glossary of atomic terms

    International Nuclear Information System (INIS)

    This glossary 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 will be found at the end. (author)

  10. 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.

  11. Achieving atomic resolution

    OpenAIRE

    John Spence

    2002-01-01

    The discovery of the nanotube in 19915 by high resolution electron microscopy (HREM), following closely on the discovery of fullerenes, has initiated a new field of science known as nanoscience. (In fact the fullerene buckyball itself was first observed in 1980, by HREM1.) While nanoscience now spans many disciplines, from molecular biology to quantum computing, for all of them, the HREM technique has become the indispensable tool for analyzing the atomic structure of individual bulk nanostru...

  12. Atomic and molecular theory

    International Nuclear Information System (INIS)

    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

  13. Atomic Properties of Lu$^+$

    OpenAIRE

    Paez, Eduardo; Arnold, K. J.; Hajiyev, Elnur; Porsev, S. G.; Dzuba, V. A.; Safronova, U. I.; Safronova, M.S.; Barrett, M. D.

    2016-01-01

    Singly ionised Lutetium has recently been suggested as a potential clock candidate. Here we report a joint experimental and theoretical investigation of \\ce{Lu^+}. Measurements relevant to practical clock operation are made and compared to atomic structure calculations. Calculations of scalar and tensor polarizabilities for clock states over a range of wavelengths are also given. These results will be useful for future work with this clock candidate.

  14. Atomic properties of Lu+

    Science.gov (United States)

    Paez, Eduardo; Arnold, K. J.; Hajiyev, Elnur; Porsev, S. G.; Dzuba, V. A.; Safronova, U. I.; Safronova, M. S.; Barrett, M. D.

    2016-04-01

    Singly ionized lutetium has recently been suggested as a potential clock candidate. Here we report a joint experimental and theoretical investigation of Lu+. Measurements relevant to practical clock operation are made and compared to atomic structure calculations. Calculations of scalar and tensor polarizabilities for clock states over a range of wavelengths are also given. These results will be useful for future work with this clock candidate.

  15. Glossary of atomic terms

    International Nuclear Information System (INIS)

    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)

  16. Parkinson's disease: insights from pathways

    OpenAIRE

    Cookson, Mark R.; Bandmann, Oliver

    2010-01-01

    Parkinson's disease (PD) typically presents in sporadic fashion, but the identification of disease-causing mutations in monogenically inherited PD genes has provided crucial insight into the pathogenesis of this disorder. Mutations in autosomal recessively inherited genes, namely parkin, PINK1 and DJ-1, typically lead to early onset parkinsonism. At least two of these genes (PINK1 and parkin) appear to work in the same pathway related to maintenance of mitochondrial functional integrity under...

  17. Philosophical Insight and Modal Cognition

    OpenAIRE

    Gerken, Mikkel

    2015-01-01

    Modal rationalists uphold a strong constitutive relationship between a priori cognition and modal cognition. Since both a priori cognition and modal cognition have been taken to be characteristic of philosophical insights, I will critically assess an ambitious modal rationalism and an associated ambitious methodological rationalism. I begin by examining Kripkean cases of the necessary a posteriori in order to characterize the ambitious modal rationalism that will be the focus of my criticism....

  18. Atomic energy utilization

    International Nuclear Information System (INIS)

    As observed worldwide, sufficient consensus has not been obtained on the peaceful utilization of atomic energy, but why has only France showed the relatively smooth advance ? Is it the result of the PR activities by enterprises ? The author visited two French nuclear facilities in June-July, 1990, and experienced the way of acceptance of the peaceful utilization of atomic energy and the action of enterprises in France. The French Electric Power Corp. (EDF) already clarified the guideline to the society about 'How to obtain the trust of public for atomic energy'. The gist of the contents of this EDF guideline is shown. The investigation by the authors can be judged as illustrating concretely the posture of enterprises to endeavor for the realization of this EDF guideline. The serious consideration on communication and community, the opening of information to public and sincere response, the fostering of the expression techniques of those in charge of PR, the immediate notice at the time of accidents, the maintenance of information transmission systems and so on carried out for 30 years contributed to the fostering of trust. The points of social psychology for national consensus and the investigation in the La Hague reprocessing plant and the Super Phenix in Creys Malville are reported. (K.I.)

  19. Australia's atomic conspiracy theory

    International Nuclear Information System (INIS)

    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

  20. Nuclear and atomic models

    International Nuclear Information System (INIS)

    A theorem concerning fermion interaction is postulated and applied to the problems of atomic (electronic) and nuclear physics. Model building based solely upon the postulate that adjacent like fermions must be singlet paired accounts for the closed shells of both nuclear and atomic structure. The implied antiferromagnetic FCC lattice of protons and neutrons in alternating layers has been found by previous workers to be the lowest-energy solid configuration of nuclear matter (N = P). The buildup of the FCC lattice from a central tetrahedron reproduces all of the shells and subshells of the isotropic harmonic oscillator, which is the basis for the shell model. In atomic structure, the singlet pairing of adjacent electrons implies closed-shell structures uniquely at the six noble gases and the three noble metals, Ni, Pd, and Pt. The basis for the postulate concerning fermions is found in terms of classical electrodynamics; it is a microscopic corollary of Biot-Savart's law that parallel currents attract whereas antiparallel currents repel. (author)

  1. 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.

  2. Into the atom and beyond

    CERN Multimedia

    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!

  3. Atom-Light Hybrid Interferometer.

    Science.gov (United States)

    Chen, Bing; Qiu, Cheng; Chen, Shuying; Guo, Jinxian; Chen, L Q; Ou, Z Y; Zhang, Weiping

    2015-07-24

    A new type of hybrid atom-light interferometer is demonstrated with atomic Raman amplification processes replacing the beam splitting elements in a traditional interferometer. This nonconventional interferometer involves correlated optical and atomic waves in the two arms. The correlation between atoms and light developed with the Raman process makes this interferometer different from conventional interferometers with linear beam splitters. It is observed that the high-contrast interference fringes are sensitive to the optical phase via a path change as well as the atomic phase via a magnetic field change. This new atom-light correlated hybrid interferometer is a sensitive probe of the atomic internal state and should find wide applications in precision measurement and quantum control with atoms and photons. PMID:26252684

  4. Nuclear effects in atomic transitions

    CERN Document Server

    Pálffy, Adriana

    2011-01-01

    Atomic electrons are sensitive to the properties of the nucleus they are bound to, such as nuclear mass, charge distribution, spin, magnetization distribution, or even excited level scheme. These nuclear parameters are reflected in the atomic transition energies. A very precise determination of atomic spectra may thus reveal information about the nucleus, otherwise hardly accessible via nuclear physics experiments. This work reviews theoretical and experimental aspects of the nuclear effects that can be identified in atomic structure data. An introduction to the theory of isotope shifts and hyperfine splitting of atomic spectra is given, together with an overview of the typical experimental techniques used in high-precision atomic spectroscopy. More exotic effects at the borderline between atomic and nuclear physics, such as parity violation in atomic transitions due to the weak interaction, or nuclear polarization and nuclear excitation by electron capture, are also addressed.

  5. Atomic physics in strong fields

    International Nuclear Information System (INIS)

    This report discusses: Microwave Driven Multiphoton Excitation Dynamics in Rydberg Atoms; Nonadiabatic Geometric Phases of Multiphoton Transitions in Dissipative Systems and Spin-j Systems; and Nonperturbative Treatments of Atomic and Molecular Processes in Intense Laser Fields

  6. Laser Spectroscopy of Muonic Atoms and Ions

    CERN Document Server

    Pohl, Randolf; Fernandes, Luis M P; Ahmed, Marwan Abdou; Amaro, Fernando D; Amaro, Pedro; Biraben, François; Cardoso, João M R; Covita, Daniel S; Dax, Andreas; Dhawan, Satish; Diepold, Marc; Franke, Beatrice; Galtier, Sandrine; Giesen, Adolf; Gouvea, Andrea L; Götzfried, Johannes; Graf, Thomas; Hänsch, Theodor W; Hildebrandt, Malte; Indelicato, Paul; Julien, Lucile; Kirch, Klaus; Knecht, Andreas; Knowles, Paul; Kottmann, Franz; Krauth, Julian J; Bigot, Eric-Olivier Le; Liu, Yi-Wei; Lopes, José A M; Ludhova, Livia; Machado, Jorge; Monteiro, Cristina M B; Mulhauser, Françoise; Nebel, Tobias; Rabinowitz, Paul; Santos, Joaquim M F dos; Santos, José Paulo; Schaller, Lukas A; Schuhmann, Karsten; Schwob, Catherine; Szabo, Csilla I; Taqqu, David; Veloso, João F C A; Voss, Andreas; Weichelt, Birgit; Antognini, Aldo

    2016-01-01

    Laser spectroscopy of the Lamb shift (2S-2P energy difference) in light muonic atoms or ions, in which one negative muon $\\mu^-$ is bound to a nucleus, has been performed. The measurements yield significantly improved values of the root-mean-square charge radii of the nuclei, owing to the large muon mass, which results in a vastly increased muon wave function overlap with the nucleus. The values of the proton and deuteron radii are 10 and 3 times more accurate than the respective CODATA values, but 7 standard deviations smaller. Data on muonic helium-3 and -4 ions is being analyzed and will give new insights. In future, the (magnetic) Zemach radii of the proton and the helium-3 nuclei will be determined from laser spectroscopy of the 1S hyperfine splittings, and the Lamb shifts of muonic Li, Be and B can be used to improve the respective charge radii.

  7. Single beam atom sorting machine

    International Nuclear Information System (INIS)

    We create two overlapping one-dimensional optical lattices using a single laser beam, a spatial light modulator and a high numerical aperture lens. These lattices have the potential to trap single atoms, and using the dynamic capabilities of the spatial light modulator may shift and sort atoms to a minimum atom-atom separation of 1.52 μm. We show how a simple feedback circuit can compensate for the spatial light modulator's intensity modulation

  8. 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...... crossdisciplinary activity. We first consider condensates of bosonic and paired systems of fermionic particles with the mean-field description, but take great care to point out potential problems in the limit of small particle numbers. Along the way we review some of the basic results of Bose–Einstein condensate...

  9. THE DYNAMICS OF HYDROGEN ATOM ABSTRACTION FROM POLYATOMIC MOLECULES.

    Energy Technology Data Exchange (ETDEWEB)

    LIU,X.; SUITS,A.G.

    2002-11-21

    The hydrogen atom abstraction reaction is an important fundamental process that is extensively involved in atmospheric and combustion chemistry. The practical significance of this type of reaction with polyatomic hydrocarbons is manifest, which has led to many kinetics studies. The detailed understanding of these reactions requires corresponding dynamics studies. However, in comparison to the A + HX {radical} AH + X reactions, the study of the dynamics of A + HR {yields} AH + R reactions is much more difficult, both experimentally and theoretically (here and in the following, A stands for an atom, X stands for a halogen atom, and R stands for a polyatomic hydrocarbon radical). The complication stems from the structured R, in contrast to the structureless X. First of all, there are many internal degrees of freedom in R that can participate in the reaction. In addition, there are different carbon sites from which an H atom can be abstracted, and the dynamics are correspondingly different; there are also multiple identical carbon sites in HR and in the picture of a local reaction, there exist competitions between neighboring H atoms, and so on. Despite this complexity, there have been continuing efforts to obtain insight into the dynamics of these reactions. In this chapter, some examples are presented, including the reactions of ground state H, Cl, and O atoms, with particular focus on our recent work using imaging to obtain the differential cross sections for these reactions.

  10. Calculations of effective atomic number

    Energy Technology Data Exchange (ETDEWEB)

    Kaliman, Z. [Department of Physics, Faculty of Arts and Sciences, Omladinska 14, Rijeka (Croatia); Orlic, N. [Department of Physics, Faculty of Arts and Sciences, Omladinska 14, Rijeka (Croatia)], E-mail: norlic@ffri.hr; Jelovica, I. [Department of Physics, Faculty of Arts and Sciences, Omladinska 14, Rijeka (Croatia)

    2007-09-21

    We present and discuss effective atomic number (Z{sub eff}) obtained by different methods of calculations. There is no unique relation between the computed values. This observation led us to the conclusion that any Z{sub eff} is valid only for given process. We illustrate calculations for different subshells of atom Z=72 and for M3 subshell of several other atoms.

  11. The International Atomic Energy Agency

    Science.gov (United States)

    Dufour, Joanne

    2004-01-01

    The dropping of atomic bombs on Hiroshima and Nagasaki in World War II inaugurated a new era in world history, the atomic age. After the war, the Soviet Union, eager to develop the same military capabilities as those demonstrated by the United States, soon rivaled the U.S. as an atomic and nuclear superpower. Faced by the possibility of…

  12. Atomic Energy Commission Act, 1963

    International Nuclear Information System (INIS)

    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. Materials on atomic energy problems

    International Nuclear Information System (INIS)

    The author cites and comments legal opinions on problems of atomic energy, i.e. the decision of the Federal Constitutional Court concerning Kalkar and the plutonium economy; Judges of the Federal Constitutional Court on technology and hazards; the 'atomic state'; plutonium at Gorleben; a new safety philosophy after Harrisburg; salt domes unsuitable for atomic waste. (HSCH) 891 HP/HSCH 892 MB

  14. Effects of atomic hydrogen and deuterium exposure on high polarization GaAs photocathodes

    Energy Technology Data Exchange (ETDEWEB)

    M. Baylac; P. Adderley; J. Brittian; J. Clark; T. Day; J. Grames; J. Hansknecht; M. Poelker; M. Stutzman; A. T. Wu; A. S. Terekhov

    2005-12-01

    Strained-layer GaAs and strained-superlattice GaAs photocathodes are used at Jefferson Laboratory to create high average current beams of highly spin-polarized electrons. High electron yield, or quantum efficiency (QE), is obtained only when the photocathode surface is atomically clean. For years, exposure to atomic hydrogen or deuterium has been the photocathode cleaning technique employed at Jefferson Laboratory. This work demonstrates that atomic hydrogen cleaning is not necessary when precautions are taken to ensure that clean photocathode material from the vendor is not inadvertently dirtied while samples are prepared for installation inside photoemission guns. Moreover, this work demonstrates that QE and beam polarization can be significantly reduced when clean high-polarization photocathode material is exposed to atomic hydrogen from an rf dissociator-style atomic hydrogen source. Surface analysis provides some insight into the mechanisms that degrade QE and polarization due to atomic hydrogen cleaning.

  15. Atomic structure and surface defects at mineral-water interfaces probed by in situ atomic force microscopy.

    Science.gov (United States)

    Siretanu, Igor; van den Ende, Dirk; Mugele, Frieder

    2016-04-14

    Atomic scale details of surface structure play a crucial role for solid-liquid interfaces. While macroscopic characterization techniques provide averaged information about bulk and interfaces, high resolution real space imaging reveals unique insights into the role of defects that are believed to dominate many aspects of surface chemistry and physics. Here, we use high resolution dynamic Atomic Force Microscopy (AFM) to visualize and characterize in ambient water the morphology and atomic scale structure of a variety of nanoparticles of common clay minerals adsorbed to flat solid surfaces. Atomically resolved images of the (001) basal planes are obtained on all materials investigated, namely gibbsite, kaolinite, illite, and Na-montmorillonite of both natural and synthetic origin. Next to regions of perfect crystallinity, we routinely observe extended regions of various types of defects on the surfaces, including vacancies of one or few atoms, vacancy islands, atomic steps, apparently disordered regions, as well as strongly adsorbed seemingly organic and inorganic species. While their exact nature is frequently difficult to identify, our observations clearly highlight the ubiquity of such defects and their relevance for the overall physical and chemical properties of clay nanoparticle-water interfaces. PMID:27030282

  16. International atomic laboratory

    International Nuclear Information System (INIS)

    Some thirty kilometers to the south-east of Vienna, in the village of Seibersdorf, the International Atomic Energy Agency will have its functional laboratory, the first atomic laboratory to be built by peaceful world-wide co-operation. The building is expected to be completed around the middle of 1960 and the scientific installations will start immediately thereafter. The staff (14 Professional and 24 of the General Service category) for the laboratory are also expected to be engaged at that time and it should be possible to start operating the laboratory in the last quarter of 1960. It is estimated that the construction work will cost about US $400 000 and the total equipment will be worth between $200 000 and $300 000. The United States Government is donating $600 000 for this purpose. The operating costs during 1961, the first full year of operation, will be a little over $240 000. The scope of the laboratory should be limited to certain broad functions. The maximum functions envisaged were: (a) standardization of isotopes and preparation of radioactive standards; (b) calibration and adaptation of measuring equipment; (c) quality control of special materials for nuclear technology; (d) measurements and analysis in connexion with the Agency's safeguards and health and safety programme; and (e) services for Member States which can be undertaken with the facilities needed for the former activities. The idea behind this recommendation will be clear if it is remembered that the research functions of the Agency are governed mostly by its other activities, by its Statutory obligation to encourage and assist peaceful atomic energy work in Member States and establish standards for health and safety and for safeguards against military use

  17. Offshore atomic power plants

    International Nuclear Information System (INIS)

    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.)

  18. Entangling atoms in bad cavities

    OpenAIRE

    Sorensen, Anders S.; Molmer, Klaus

    2002-01-01

    We propose a method to produce entangled spin squeezed states of a large number of atoms inside an optical cavity. By illuminating the atoms with bichromatic light, the coupling to the cavity induces pairwise exchange of excitations which entangles the atoms. Unlike most proposals for entangling atoms by cavity QED, our proposal does not require the strong coupling regime g^2/\\kappa\\Gamma>> 1, where g is the atom cavity coupling strength, \\kappa is the cavity decay rate, and \\Gamma is the dec...

  19. Atomic data for fusion

    International Nuclear Information System (INIS)

    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

  20. Dynamical polarizability of atoms

    International Nuclear Information System (INIS)

    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)

  1. Radioiodine: The atomic cocktail

    International Nuclear Information System (INIS)

    The use of artificial radionuclides in medicine has continued to increase in importance resulting in the growth of a new medical specialty, Nuclear Medicine. The availability of very low cost radionuclides from Oak Ridge beginning in 1946 initiated a revolution that led to widespread use of 131I in the understanding and management of thyroid disease and to extensive use of 131I-labeled dyes, fats, drugs, proteins and other substances in diverse areas of medicine. While the role of the 'atomic cocktail' in cancer therapy has diminished greatly, in vivo and in vitro radionuclide procedures in medical diagnosis are employed in over one-third of hospital admissions

  2. Atoms for peace awards

    International Nuclear Information System (INIS)

    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)

  3. 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.

  4. Atom-Photon Entanglement

    OpenAIRE

    Volz, Jürgen

    2006-01-01

    Verschränkung ist das Schlüsselelement vieler Experimente in der Quantenkommunikation und -information. Besonders im Hinblick auf zukünftige Anwendungen wie den Aufbau von Quantennetzwerken ist Verschränkung von unterschiedlichen Quantensystemen wie z.B. Atomen und Photonen unentbehrlich, da sie die Schnittstelle zwischen atomaren Quantenspeichern und optischen Kommunikationskanälen darstellt und die Verteilung von Verschränkung über große Entfernungen ermöglicht. Darüber hinaus ist Atom-Phot...

  5. Achieving atomic resolution

    Directory of Open Access Journals (Sweden)

    John Spence

    2002-04-01

    Full Text Available The discovery of the nanotube in 19915 by high resolution electron microscopy (HREM, following closely on the discovery of fullerenes, has initiated a new field of science known as nanoscience. (In fact the fullerene buckyball itself was first observed in 1980, by HREM1. While nanoscience now spans many disciplines, from molecular biology to quantum computing, for all of them, the HREM technique has become the indispensable tool for analyzing the atomic structure of individual bulk nanostructural elements. However this method has long been the technique of choice whenever questions of microstructural characterization arise in materials science.

  6. 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.)

  7. The coupled atom transistor

    International Nuclear Information System (INIS)

    We describe the first implementation of a coupled atom transistor where two shallow donors (P or As) are implanted in a nanoscale silicon nanowire and their electronic levels are controlled with three gate voltages. Transport spectroscopy through these donors placed in series is performed both at zero and microwave frequencies. The coherence of the charge transfer between the two donors is probed by Landau–Zener–Stückelberg interferometry. Single-charge transfer at zero bias (electron pumping) has been performed and the crossover between the adiabatic and non-adiabatic regimes is studied. (paper)

  8. The INSIGHT SEIS VBB Experiment

    Science.gov (United States)

    Tillier, S.; De Raucourt, S.; Lognonne, P. H.; Banerdt, B.; Mimoun, D.; Giardini, D.; Christensen, U. R.; Pike, W. T.; Zweifel, P.; Mance, D.; Bierwirth, M.; Laudet, P.; Perez, R.; Kerjean, L.; Hurst, K. J.; Mocquet, A.; Garcia, R. F.

    2012-12-01

    The SEIS experiment is the primary payload of the Interior Structure investigation using Seismology and Heat Transport (INSIGHT) Mission Proposal, submitted to NASA in the frame of the 2010 Discovery program, and selected for a competitive phase A study, together with two other projects. The objective of the INSIGHT SEIS experiment is the determination of the deep internal structure of Mars. In particular, geophysical parameters of first importance, such as the state (liquid/solid) and size of the core, structure of the mantle, shape of discontinuities, thickness of the crust will be determined by the experiment. It will measure seismic activity in a very broad band of signal, from the tidal frequencies (0.05 mHz) up to the short period frequencies (50 Hz), to address the widest range of scientific questions, from the state of the core to the meteoritic impact and quake rates. The instrument integrates a Very Broad Band (VBB) 3 axis seismometer, completed by another trihedron of MEMS short period seismometers, environmental sensors for pressure, wind and temperature, The sensors will be deployed on the Martian ground by a robotic arm from a Phoenix-type lander platform and protected by a wind and thermal shield. The sensor assembly, which contains all seismic sensors, the leveling system, as well as house-keeping and temperature measurements, will be deployed on the soil in order to allow the best possible mechanical coupling with the ground motion. The wind and thermal shield, the sensors' specific containers (vacuum sphere for VBBs) and a passive thermal compensation system will achieve a very high protection of the VBB against temperature and pressure variations, allowing the sensor to operate in the rough Martian thermal environment while reaching a deection threshold below 10-9 ms-2 Hz-1/2 in the VBB bandwidth. A dedicated electronics will manage the overall experiment and ultra-low noise, space qualified 24 bits A/D converters will perform the acquisition

  9. Doping of Semiconducting Atomic Chains

    Science.gov (United States)

    Toshishige, Yamada; Kutler, Paul (Technical Monitor)

    1997-01-01

    Due to the rapid progress in atom manipulation technology, atomic chain electronics would not be a dream, where foreign atoms are placed on a substrate to form a chain, and its electronic properties are designed by controlling the lattice constant d. It has been shown theoretically that a Si atomic chain is metallic regardless of d and that a Mg atomic chain is semiconducting or insulating with a band gap modified with d. For electronic applications, it is essential to establish a method to dope a semiconducting chain, which is to control the Fermi energy position without altering the original band structure. If we replace some of the chain atoms with dopant atoms randomly, the electrons will see random potential along the chain and will be localized strongly in space (Anderson localization). However, if we replace periodically, although the electrons can spread over the chain, there will generally appear new bands and band gaps reflecting the new periodicity of dopant atoms. This will change the original band structure significantly. In order to overcome this dilemma, we may place a dopant atom beside the chain at every N lattice periods (N > 1). Because of the periodic arrangement of dopant atoms, we can avoid the unwanted Anderson localization. Moreover, since the dopant atoms do not constitute the chain, the overlap interaction between them is minimized, and the band structure modification can be made smallest. Some tight-binding results will be discussed to demonstrate the present idea.

  10. Approaching the Distinction between Intuition and Insight.

    Science.gov (United States)

    Zhang, Zhonglu; Lei, Yi; Li, Hong

    2016-01-01

    Intuition and insight share similar cognitive and neural basis. Though, there are still some essential differences between the two. Here in this short review, we discriminated between intuition, and insight in two aspects. First, intuition, and insight are toward different aspects of information processing. Whereas intuition involves judgment about "yes or no," insight is related to "what" is the solution. Second, tacit knowledge play different roles in between intuition and insight. On the one hand, tacit knowledge is conducive to intuitive judgment. On the other hand, tacit knowledge may first impede but later facilitate insight occurrence. Furthermore, we share theoretical, and methodological views on how to access the distinction between intuition and insight. PMID:27555833

  11. Experiments in cold atom optics towards precision atom interferometry

    Science.gov (United States)

    Aveline, David C.

    Atom optics has been a highly active field of research with many scientific breakthroughs over the past two decades, largely due to successful advances in laser technology, microfabrication techniques, and the development of laser cooling and trapping of neutral atoms. This dissertation details several atom optics experiments with the motivation to develop tools and techniques for precision atom wave interferometry. It provides background information about atom optics and the fundamentals behind laser cooling and trapping, including basic techniques for cold gas thermometry and absorptive detection of atoms. A brief overview of magnetic trapping and guiding in tight wire-based traps is also provided before the experimental details are presented. We developed a novel laser source of 780 nm light using frequency-doubled 1560 nm fiber amplifier. This laser system provided up to a Watt of tunable frequency stabilized light for two Rb laser cooling and trapping experiments. One system generates Bose-Einstein condensates in an optical trap while the second is based on atom chip magnetic traps. The atom chip system, detailed in this thesis, was designed and built to develop the tools necessary for transport and loading large numbers of cold atoms and explore the potential for guided atom interferometry. Techniques and results from this experiment are presented, including an efficient magnetic transport and loading method to deliver cold atom to atom chip traps. We also developed a modeling tool for the magnetic fields formed by coiled wire geometries, as well as planar wire patterns. These models helped us design traps and determine adiabatic transportation of cold atoms between macro-scale traps and micro-traps formed on atom chips. Having achieved near unity transfer efficiency, we demonstrated that this approach promises to be a consistent method for loading large numbers of atoms into micro-traps. Furthermore, we discuss an in situ imaging technique to investigate

  12. 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.

  13. Ghost Imaging with Atoms

    CERN Document Server

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

    2016-01-01

    Ghost imaging is a technique -- first realized in quantum optics -- in which the image emerges from cross-correlation between particles in two separate beams. One beam passes through the object to a bucket (single-pixel) detector, while the second beam's spatial profile is measured by a high resolution (multi-pixel) detector but never interacts with the object. Neither detector can reconstruct the image independently. However, until now ghost imaging has only been demonstrated with photons. Here we report the first realisation of ghost imaging of an object using massive particles. In our experiment, the two beams are formed by correlated pairs of ultracold metastable helium atoms, originating from two colliding Bose-Einstein condensates (BECs) via $s$-wave scattering. We use the higher-order Kapitza-Dirac effect to generate the large number of correlated atom pairs required, enabling the creation of a ghost image with good visibility and sub-millimetre resolution. Future extensions could include ghost interfe...

  14. Neutrinos, atoms and gravity

    International Nuclear Information System (INIS)

    A interesting overview of ongoing developments in neutrino physics and recent advances in atomic and optical physics and in gravitation emerged from the recent 'Moriond' Workshop on Perspectives in Neutrinos, Atomic Physics and Gravitation Theory, held from January 30 to February 6 at Villars sur Ollon in the Swiss Alps. Neutrino physics is a Moriond tradition, and the Workshop began with presentations of new measurements of the tritium beta spectrum by the Livermore and Mainz groups, setting limits on the mass of electron (anti)neutrino of 8 eV and 7.2 eV respectively. It is puzzling that the five most advanced experiments setting upper limits on the electron (anti)neutrino mass (Livermore, Los Alamos, Mainz, Tokyo and Zurich) report negative best-fit values for the square of the neutrino mass, with a weighted average of -59 ±177 ± 26 eV2. This corresponds to an excess of counts near the tritium endpoint, rather than a deficit which would indicate a nonzero neutrino mass. Gerry Stephenson presented a possible explanation, invoking a very light (or massless) scalar boson coupled only to neutrinos. Perhaps more plausibly, a systematic effect may be the cause, and further studies are underway. Nonetheless, the limits are unlikely to change significantly, and the results exclude electron neutrinos as the possible dominant component of dark matter. The solar neutrino problem persists

  15. Interstellar Atomic Abundances

    CERN Document Server

    Jenkins, E B

    2003-01-01

    A broad array of interstellar absorption features that appear in the ultraviolet spectra of bright sources allows us to measure the abundances and ionization states of many important heavy elements that exist as free atoms in the interstellar medium. By comparing these abundances with reference values in the Sun, we find that some elements have abundances relative to hydrogen that are approximately consistent with their respective solar values, while others are depleted by factors that range from a few up to around 1000. These depletions are caused by the atoms condensing into solid form onto dust grains. Their strengths are governed by the volatility of compounds that are produced, together with the densities and velocities of the gas clouds. We may characterize the depletion trends in terms of a limited set of parameters; ones derived here are based on measurements of 15 elements toward 144 stars with known values of N(H I) and N(H2). In turn, these parameters may be applied to studies of the production, de...

  16. B and N ion implantation into carbon nanotubes: Insight from atomistic simulations

    International Nuclear Information System (INIS)

    By employing atomistic computer simulations with empirical potential and density functional force models, we study B/N ion implantation onto carbon nanotubes. We simulate irradiation of single-walled nanotubes with B and N ions and show that up to 40% of the impinging ions can occupy directly the sp2 positions in the nanotube atomic network. We further estimate the optimum ion energies for direct substitution. Ab initio simulations are used to get more insight into the structure of the typical atomic configurations which appear under the impacts of the ions. As annealing should further increase the number of sp2 impurities due to dopant atom migration and annihilation with vacancies, we also study migration of impurity atoms over the tube surface. Our results indicate that irradiation-mediated doping of nanotubes is a promising way to control the nanotube electronic and even mechanical properties due to impurity-stimulated crosslinking of nanotubes

  17. Mapping Out Atom-Wall Interaction with Atomic Clocks

    International Nuclear Information System (INIS)

    We explore the feasibility of probing atom-wall interaction with atomic clocks based on atoms trapped in engineered optical lattices. Optical lattice is normal to the wall. By monitoring the wall-induced clock shift at individual wells of the lattice, one would measure the dependence of the atom-wall interaction on the atom-wall separation. We find that the induced clock shifts are large and observable at already experimentally demonstrated levels of accuracy. We show that this scheme may uniquely probe the long-range atom-wall interaction in all three qualitatively distinct regimes of the interaction: van der Waals (image-charge interaction), Casimir-Polder (QED vacuum fluctuations), and Lifshitz (thermal-bath fluctuations) regimes.

  18. Insight into Enabling Adaptive Management

    Directory of Open Access Journals (Sweden)

    Lorne A. Greig

    2013-09-01

    Full Text Available The U.S. National Commission on Science for Sustainable Forestry recognized a need for effective adaptive management to support management for biological diversity. However, difficulties in implementing adaptive management in the U.S. Northwest Forest Plan led the Commission to wonder if comparisons across multiple adaptive management trials in the forest sector could provide insight into the factors that serve to enable or inhibit adaptive management. This comparison and the resulting discussions among a group of seasoned practitioners, with adaptive management experience at a variety of scales and levels of complexity, led to insights into a hierarchy of ten factors that can serve to either enable or inhibit implementation. Doing high quality adaptive management is about doing good science to enable learning from management experience. Enabling adaptive management though is about working with people to understand their concerns, to develop a common understanding and an environment of trust that allows adaptive management to proceed. Careful attention to enabling factors is critical to fulfilling the promise of adaptive management.

  19. Nuclear polarization in heavy atoms and superheavy quasi-atoms

    International Nuclear Information System (INIS)

    Object of this thesis are nuclear polarization effects in electronic atoms and quasi-atoms. We show how the contribution of the nuclear polarization increases if the interaction with low-lying collective nuclear excitations is regarded. In the framework of model calculations we study whether in superheavy quasi-atoms nuclear polarization effects can lead to comparable energy shifts as those which are generated because of usual QED radiative corrections. (orig./HSI)

  20. Single atom spintronics

    International Nuclear Information System (INIS)

    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

  1. Cooperative scattering of light and atoms in ultracold atomic gases

    Science.gov (United States)

    Uys, H.; Meystre, P.

    2008-07-01

    Superradiance and coherent atomic recoil lasing are two closely related phenomena, both resulting from the cooperative scattering of light by atoms. In ultracold atomic gases below the critical temperature for Bose-Einstein condensation these processes take place with the simultaneous amplification of the atomic matter waves. We explore these phenomena by surveying some of the experimental and theoretical developments that have emerged in this field of study since the first observation of superradiant scattering from a Bose-Einstein condensate in 1999 [1].

  2. Cooperative scattering of light and atoms in ultracold atomic gases

    International Nuclear Information System (INIS)

    Superradiance and coherent atomic recoil lasing are two closely related phenomena, both resulting from the cooperative scattering of light by atoms. In ultracold atomic gases below the critical temperature for Bose-Einstein condensation these processes take place with the simultaneous amplification of the atomic matter waves. We explore these phenomena by surveying some of the experimental and theoretical developments that have emerged in this field of study since the first observation of superradiant scattering from a Bose-Einstein condensate in 1999 [1

  3. Atomic Data: Division B / Commission 14 / Working Group Atomic Data

    CERN Document Server

    Nave, Gillian; Zhao, Gang

    2015-01-01

    This report summarizes laboratory measurements of atomic wavelengths, energy levels, hyperfine and isotope structure, energy level lifetimes, and oscillator strengths. Theoretical calculations of lifetimes and oscillator strengths are also included. The bibliography is limited to species of astrophysical interest. Compilations of atomic data and internet databases are also included. Papers are listed in the bibliography in alphabetical order, with a reference number in the text. Comprehensive lists of references for atomic spectra can be found in the NIST Atomic Spectra Bibliographic Databases http://physics.nist.gov/asbib.

  4. Atomic Bremsstrahlung in ion-atom collisions (stripping)

    International Nuclear Information System (INIS)

    Atomic Bremsstrahlung produced in high energy (non relativistic) ion-atom collisions including retardation effects is studied. Mechanical states of the system are described by the symmetrical eikonal approximation and Hartree-Fock electronic wave functions for the calculation of the shape factor of each atom. Photon energy spectra are presented for collisions of protons against noble gases, Ne, Ar, Kr and Xe. The contribution of each atomic shell to these spectra is studied, where lowest shell (1s) corresponds to the hard X-ray region and the higher shells correspond to lower photon energies. (Author)

  5. When higher working memory capacity hinders insight.

    Science.gov (United States)

    DeCaro, Marci S; Van Stockum, Charles A; Wieth, Mareike B

    2016-01-01

    Higher working memory capacity (WMC) improves performance on a range of cognitive and academic tasks. However, a greater ability to control attention sometimes leads individuals with higher WMC to persist in using complex, attention-demanding approaches that are suboptimal for a given task. We examined whether higher WMC would hinder insight problem solving, which is thought to rely on associative processes that operate largely outside of close attentional control. In addition, we examined whether characteristics of the insight problems influence whether this negative relationship will be revealed. In Experiment 1, participants completed matchstick arithmetic problems, which require a similar initial problem representation for all problems. Higher WMC was associated with less accurate insight problem solving. In Experiment 2, participants completed insight word problems, which require substantially different representations for each problem. Higher WMC was again negatively associated with insight, but only after statistically controlling for shared variance between insight and incremental problem-solving accuracy. These findings suggest that WMC may benefit performance on fundamental processes common to both incremental and insight problem solving (e.g., initial problem representation), but hinder performance on the processes that are unique to insight (e.g., solution and restructuring). By considering the WMC of the individual, and the nature of the insight task, we may better understand the process of insight and how to best support it. (PsycINFO Database Record PMID:26120772

  6. Quantum mechanical study of the coupling of plasmon excitations to atomic-scale electron transport

    International Nuclear Information System (INIS)

    The coupling of optical excitation and electron transport through a sodium atom in a plasmonic dimer junction is investigated using time-dependent density functional theory. The optical absorption and dynamic conductance is determined as a function of gap size. Surface plasmons are found to couple to atomic-scale transport through several different channels including dipolar, multipolar, and charge transfer plasmon modes. These findings provide insight into subnanoscale couplings of plasmons and atoms, a subject of general interest in plasmonics and molecular electronics.

  7. Atomic war field Europe

    International Nuclear Information System (INIS)

    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)

  8. War against the atom

    International Nuclear Information System (INIS)

    The author reviews first the facts about atoms and nuclear energy, then assembles data and facts from recent publications maligning nuclear power. He then presents the facts dealing with: the radiation threat of a functioning nuclear reactor and its fuel cycle; the facts about plutonium, its proliferation, and the breeder reactor; the anti-nuclear movement's discussion of insurance; waste disposal; environmental aspects; economics; and risks of nuclear power compared to other energy industries--coal, natural gas, and hydropower. Mr. McCracken concludes that the most promising source of energy under development is fusion, but the technology is not yet workable. For the near term, he adds, the choice is between nuclear fission and coal. He reviews the facts of recent campaigns to abolish nuclear power in seven states and the failure in each case

  9. Entanglement enhanced atomic gyroscope

    CERN Document Server

    Cooper, J J; Dunningham, J A

    2010-01-01

    The advent of increasingly precise gyroscopes has played a key role in the technological development of navigation systems. Ring-laser and fibre-optic gyroscopes, for example, are widely used in modern inertial guidance systems and rely on the interference of unentangled photons to measure mechanical rotation. The sensitivity of these devices scales with the number of particles used as $1/ \\sqrt{N}$. Here we demonstrate how, by using sources of entangled particles, it is possible to do better and even achieve the ultimate limit allowed by quantum mechanics where the precision scales as 1/N. We propose a gyroscope scheme that uses ultra-cold atoms trapped in an optical ring potential.

  10. Atomic iodine laser

    International Nuclear Information System (INIS)

    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

  11. Atomic liability panel

    International Nuclear Information System (INIS)

    It is generally recognized that the lack of adequate rules and accepted definitions of liability in the case of nuclear accidents constitutes a serious drawback to the growth of the atomic energy industry. This applies both t o national undertakings and, more particularly, to bilateral or international operations such as those carried out under the auspices of IAEA. The problems will grow even more complicated if countries adopt differing standards. The initial programme of IAEA therefore stresses the need for the establishment of international standards and definitions of areas of responsibility which would do much to harmonize national practices now being formulated in many countries. In order to initiate studies of this problem, the Director General has decided t o call a number of experts, representing various legal systems, together, and entrust them with the task of examining this question. He has appointed Ambassador Paul Ruegger (Switzerland) as Chairman of the panel

  12. Atomic iodine laser

    Energy Technology Data Exchange (ETDEWEB)

    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.

  13. Optical nanofibres and neutral atoms

    CERN Document Server

    Nieddu, Thomas; Chormaic, Sile Nic

    2015-01-01

    Optical nanofibres are increasingly being used in cold atom experiments due to their versatility and the clear advantages they have when developing all-fibred systems for quantum technologies. They provide researchers with a method of overcoming the Rayleigh range for achieving high intensities in a focussed beam over a relatively long distance, and can act as a noninvasive tool for probing cold atoms. In this review article, we will briefly introduce the theory of mode propagation in an ultrathin optical fibre and highlight some of the more significant theoretical and experimental progresses to date, including the early work on atom probing, manipulation and trapping, the study of atom-dielectric surface interactions, and the more recent observation of nanofibre-mediated nonlinear optics phenomena in atomic media. The functionality of optical nanofibres in relation to the realisation of atom-photon hybrid quantum systems is also becoming more evident as some of the earlier technical challenges are surpassed ...

  14. Interacting atoms in optical lattices

    OpenAIRE

    Mentink, Johan; Kokkelmans, Servaas

    2008-01-01

    We propose an easy to use model to solve for interacting atoms in an optical lattice. This model allows for the whole range of weakly to strongly interacting atoms, and it includes the coupling between relative and center-of-mass motion via anharmonic lattice terms. We apply this model to a high-precision spin dynamics experiment, and we discuss the corrections due to atomic interactions and the anharmonic coupling. Under suitable experimental conditions, energy can be transferred between the...

  15. Atomic spectrometry update : environmental analysis

    OpenAIRE

    Butler, Owen T.; Cairns, Warren R. L.; Cook, Jennifer M.; Davidson, Christine M.

    2012-01-01

    This is the 27th annual review published in Journal of Analytical Atomic Spectrometry of the application of atomic spectrometry to the chemical analysis of environmental samples. This Update refers to papers published approximately between September 2010 and August 2011 and continues the series of Atomic Spectrometry Updates (ASUs) in Environmental Analysis1 that should be read in conjunction with other related ASU reviews in the series, namely: clinical and biological materials, foods and be...

  16. Nuclear effects in atomic transitions

    OpenAIRE

    Pálffy, Adriana

    2011-01-01

    Atomic electrons are sensitive to the properties of the nucleus they are bound to, such as nuclear mass, charge distribution, spin, magnetization distribution, or even excited level scheme. These nuclear parameters are reflected in the atomic transition energies. A very precise determination of atomic spectra may thus reveal information about the nucleus, otherwise hardly accessible via nuclear physics experiments. This work reviews theoretical and experimental aspects of the nuclear effects ...

  17. Atomic spectrometry update : environmental analysis

    OpenAIRE

    Butler, Owen T.; Warren R. L. Cairns; Cook, Jennifer M.; Davidson, Christine M.

    2013-01-01

    This is the 28th annual review published in JAAS on the application of atomic spectrometry to the chemical analysis of environmental samples. This Update refers to papers published approximately between September 2011 and August 2012 and continues the series of Atomic Spectrometry Updates (ASUs) in Environmental Analysis1 that should be read in conjunction with other related ASUs in the series, namely: clinical and biological materials, foods and beverages2; advances in atomic spectrometry an...

  18. Molecular invariants: atomic group valence

    International Nuclear Information System (INIS)

    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)

  19. Quantum synapse for cold atoms

    CERN Document Server

    Kouzaev, G A

    2007-01-01

    In this paper, the quantum synaptic effect is studied that arisen in the system of two crossed wires excited by the static (DC) and radio-frequency (RF) currents. The potential barrier between the two orthogonal atom streams is controlled electronically and the atoms can be transferred from one wire to another under certain critical values of the RF and DC currents. The results are interesting in the study of quantum interferometry and quantum registering of cold atoms.

  20. Study on laser atomic spectroscopy

    International Nuclear Information System (INIS)

    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)

  1. Accident management insights from IPE's

    International Nuclear Information System (INIS)

    In response to the U.S. Nuclear Regulatory Commission's Generic Letter 88-20, each utility in the U.S.A. has undertaken a probabilistic severe accident study of each plant. This paper provides a high level summary of the generic PWR accident management insights that have been obtained from the IPE reports. More importantly, the paper details some of the limitations of the IPE studies with respect to accident management. The IPE studies and the methodology used was designed to provide a best estimate of the potential for a severe accident and/or for severe consequences from a core damage accident. The accepted methodology employs a number of assumptions to make the objective attainable with a reasonable expenditure of resources. However, some of the assumptions represent limitations with respect to developing an accident management program based solely on the IPE and its results. (author)

  2. Managing complexity insights, concepts, applications

    CERN Document Server

    Helbing, Dirk

    2007-01-01

    Each chapter in Managing Complexity focuses on analyzing real-world complex systems and transferring knowledge from the complex-systems sciences to applications in business, industry and society. The interdisciplinary contributions range from markets and production through logistics, traffic control, and critical infrastructures, up to network design, information systems, social conflicts and building consensus. They serve to raise readers' awareness concerning the often counter-intuitive behavior of complex systems and to help them integrate insights gained in complexity research into everyday planning, decision making, strategic optimization, and policy. Intended for a broad readership, the contributions have been kept largely non-technical and address a general, scientifically literate audience involved in corporate, academic, and public institutions.

  3. 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 of...... accelerators for producing intense positron pulses will be discussed in the context of atomic physics experiments....

  4. 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....

  5. Fisher Information and Atomic Structure

    CERN Document Server

    Chatzisavvas, K Ch; Panos, C P; Moustakidis, Ch C

    2013-01-01

    We present a comparative study of several information and statistical complexity measures in order to examine a possible correlation with certain experimental properties of atomic structure. Comparisons are also carryed out quantitatively using Pearson correlation coefficient. In particular, we show that Fisher information in momentum space is very sensitive to shell effects, and is directly associated with some of the most characteristic atomic properties, such as atomic radius, ionization energy, electronegativity, and atomic dipole polarizability. Finally we present a relation that emerges between Fisher information and the second moment of the probability distribution in momentum space i.e. an energy functional of interest in (e,2e) experiments.

  6. Optical atomic clocks and metrology

    Science.gov (United States)

    Ludlow, Andrew

    2014-05-01

    The atomic clock has long demonstrated the capability to measure time or frequency with very high precision. Consequently, these clocks are used extensively in technological applications such as advanced synchronization or communication and navigation networks. Optical atomic clocks are next- generation timekeepers which reference narrowband optical transitions between suitable atomic states. Many optical time/frequency standards utilize state-of-the-art quantum control and precision measurement. Combined with the ultrahigh quality factors of the atomic resonances at their heart, optical atomic clocks have promised new levels of timekeeping precision, orders of magnitude higher than conventional atomic clocks based on microwave transitions. Such measurement capability enables and/or enhances many of the most exciting applications of these clocks, including the study of fundamental laws of physics through the measurement of time evolution. Here, I will highlight optical atomic clocks and their utility, as well as review recent advances in their development and performance. In particular, I will describe in detail the optical lattice clock and the realization of frequency measurement at the level of one part in 1018. To push the performance of these atomic timekeepers to such a level and beyond, several key advances are being explored worldwide. These will be discussed generally, with particular emphasis on our recent efforts at NIST in developing the optical lattice clock based on atomic ytterbium.

  7. Atomic CP-violating polarizability

    OpenAIRE

    Ravaine, Boris; Kozlov, M. G.; Derevianko, Andrei

    2005-01-01

    Searches for CP violating effects in atoms and molecules provide important constrains on competing extensions to the standard model of elementary particles. In particular, CP violation in an atom leads to the CP-odd (T,P-odd) polarizability $\\beta^\\mathrm{CP}$: a magnetic moment $\\mu^\\mathrm{CP}$ is induced by an electric field $\\mathcal{E}_0$ applied to an atom, $\\mu^\\mathrm{CP} = \\beta^\\mathrm{CP} \\mathcal{E}_0 $. We estimate the CP-violating polarizability for rare-gas (diamagnetic) atoms ...

  8. Insight, distress and coping styles in schizophrenia

    OpenAIRE

    Cooke, Michael; Peters, Emmanuelle; Fannon, Dominic; Anilkumar, Anantha P.P.; Aasen, Ingrid; Kuipers, Elizabeth; Kumari, Veena

    2007-01-01

    Background The stigma and negative societal views attached to schizophrenia can make the diagnosis distressing. There is evidence that poor insight into symptoms of the disorder and need for treatment may reflect the use of denial as a coping style. However, the relationships between insight and other coping styles have seldom been investigated. Method We examined the associations between insight, distress and a number of coping styles in 65 outpatients with schizophrenia (final n = 57) in a ...

  9. Investigation of insight with magic tricks

    OpenAIRE

    Faber, Amory

    2012-01-01

    This thesis proposes a new approach to investigate insight problem solving. Introducing magic tricks as a problem solving task, we asked participants to find out the secret method used by the magician to create the magic effect. Based on the theoretical framework of the representational change theory, we argue that magic tricks are ideally suited to investigate insight because similar to established insight tasks like puzzles, observers’ prior knowledge activates constraints. In order to see ...

  10. Course of insight in manic episode

    OpenAIRE

    Kumar, A; Kumar, S; N M Khan; Mishra, S.

    2013-01-01

    Background: Insight is an important factor associated with non compliance and poor outcome. Poor level of insight has been described as a characteristic in patients with acute bipolar disorder with more unawareness in social consequences with increasing severity in manic episode. Aim: Main aim of study was to see the baseline and longitudinal relationship between dimensions of insight with improvement in psychopathology. Setting and Design: Forty four patients diagnosed with mania, were selec...

  11. Insight and theory of mind in schizophrenia

    OpenAIRE

    Ng, Rowena; Fish, Scott; Granholm, Eric

    2014-01-01

    Theory of mind (ToM) impairment is common in individuals with schizophrenia and is associated with poor social functioning. Poor insight has also been linked to poor outcome in schizophrenia. Social developmental research has shown representations of self (insight) and representations of others (ToM) are related. In schizophrenia, contradictory reports of associations between insight and ToM have emerged, possibly due to a failure to account for neurocognitive impairments and symptoms associa...

  12. High Rydberg atoms: newcomers to the atomic physics scene

    International Nuclear Information System (INIS)

    A description is given of high Rydberg atoms which have a greatly increased size due to their having been perturbed in certain ways. The production, detection, and research on these atoms are considered. The motivation for such studies, apart from their intrinsic interest, includes laser development, laser isotope separation, energy deposition in gases, plasma diagnostics, and radio astronomy

  13. Atomic masses 1995. The 1995 atomic mass evaluation

    International Nuclear Information System (INIS)

    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)

  14. Testing Atom and Neutron Neutrality with Atom Interferometry

    OpenAIRE

    Arvanitaki, Asimina; Dimopoulos, Savas; Geraci, Andrew A.; Hogan, Jason; Kasevich, Mark

    2007-01-01

    We propose an atom-interferometry experiment based on the scalar Aharonov-Bohm effect which detects an atom charge at the 10^{-28}e level, and improves the current laboratory limits by 8 orders of magnitude. This setup independently probes neutron charges down to 10^{-28}e, 7 orders of magnitude below current bounds.

  15. Introduction to light forces, atom cooling, and atom trapping

    OpenAIRE

    Savage, Craig

    1995-01-01

    This paper introduces and reviews light forces, atom cooling and atom trapping. The emphasis is on the physics of the basic processes. In discussing conservative forces the semi-classical dressed states are used rather than the usual quantized field dressed states.

  16. Atomic Fresnel images and possible applications in atom lithography

    OpenAIRE

    Janicke, U.; M. Wilkens

    1994-01-01

    In the near field regime of diffractive atom optics, amplitude corrugations of the de Broglie wave front are important and can lead to interesting effects. One class of near field phenomena is the formation of Fresnel images. We study this effect and possible applications in atom lithography using wave packet simulations.

  17. Atomic masses 1993. The 1993 atomic mass evaluation

    International Nuclear Information System (INIS)

    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. Atomic arrangement and the formation of partially coherent interfaces in the Ti-V-N system

    International Nuclear Information System (INIS)

    The precipitation of (V,Ti) (bcc structure) in a (Ti,V)N (NaCl structure) matrix is considered in the current study. The lattice parameter ratio of this system, af/ab = 1.34, is quite different from most previous studies (af/ab ∼ 1.26) and provides an opportunity to test recent models proposed for the formation of precipitate morphology and the interface structure. Like many other fcc:bcc precipitation systems, the Ti-V-N system involves an invariant line transformation strain. In this system, the invariant line is associated with a high-index orientation relationship (OR). The observed OR is in good agreement with a predicted relationship based upon a geometric matching criterion proposed by Ryan et al. The Burgers vectors for the interfacial defects were determined directly by making high-resolution transmission electron microscope (HRTEM) observations along three different directions. The observations confirm that the formation of the precipitate facets, the spacings of misfit dislocations, and the direction of interfacial defects all agree with atom-matching considerations

  19. Bright Solitons in an Atomic Tunnel Array with Either Attractive or Repulsive Atom-Atom Interactions

    Institute of Scientific and Technical Information of China (English)

    YANG Xiao-Xue; YOU Jun; WU Ying

    2004-01-01

    @@ Taking a coherent state representation, we derive the nonlinear Schrodinger-type differential-difference equations from the quantized model of an array of traps containing Bose-Einstein condensates and linked by the tunnelling process among the adjacent traps. It is shown that no matter whether two-body interactions among atoms are repulsive or attractive, a nearly uniform atom distribution can evolve into a bright soliton-type localized ensemble of atoms and a lump of atom distribution can also be smeared out by redistributing atoms among traps under appropriate initial phase differences of atoms in adjacent traps. These two important features originate from the tailoring effect of the initial phase conditions in coherent tunnelling processes, which differs crucially from the previous tailoring effect coming mainly from the periodicity of optical lattices.

  20. Atom-surface studies with Rb Rydberg atoms

    Science.gov (United States)

    Chao, Yuanxi; Sheng, Jiteng; Sedlacek, Jonathon; Shaffer, James

    2015-05-01

    We report on experimental and theoretical progress studying atom-surface interactions using rubidium Rydberg atoms. Rydberg atoms can be strongly coupled to surface phonon polariton (SPhP) modes of a dielectric material. The coherent interaction between Rydberg atoms and SPhPs has potential applications for quantum hybrid devices. Calculations of TM-mode SPhPs on engineered surfaces of periodically poled lithium niobate (PPLN) and lithium tantalate (PPLT) for different periodic domains and surface orientations, as well as natural materials such as quartz, are presented. Our SPhP calculations account for the semi-infinite anisotropic nature of the materials. In addition to theoretical calculations, we show experimental results of measurements of adsorbate fields and coupling of Rydberg atoms to SPhPs on quartz.

  1. Demonstration of a cold atom beam splitter on atom chip

    Science.gov (United States)

    Jiang, Xiaojun; Li, Xiaolin; Zhang, Haichao; Wang, Yuzhu

    2016-08-01

    We report an experimental demonstration of a new scheme to split cold atoms on an atom chip. The atom chip consists of a U-wire and a Z-wire. The cold atom cloud is initially loaded and prepared in the Z-trap, which is split into two separate parts by switching on the current of the U-wire. The two separate atom clouds have a distance more than one millimeter apart from each other and show almost symmetrical profiles, corresponding to about a 50/50 splitting ratio. Project supported by the State Key Basic Research Program of China (Grant No. 2011CB921504) and the National Natural Science Foundation of China (Grant No. 91536107).

  2. Coherent Atom Optics with fast metastable rare gas atoms

    Science.gov (United States)

    Grucker, J.; Baudon, J.; Karam, J.-C.; Perales, F.; Bocvarski, V.; Vassilev, G.; Ducloy, M.

    2006-12-01

    Coherent atom optics experiments making use of an ultra-narrow beam of fast metastable atoms generated by metastability exchange are reported. The transverse coherence of the beam (coherence radius of 1.7 μm for He*, 1.2 μm for Ne*, 0.87 μm for Ar*) is demonstrated via the atomic diffraction by a non-magnetic 2μm-period reflection grating. The combination of the non-scalar van der Waals (vdW) interaction with the Zeeman interaction generated by a static magnetic field gives rise to "vdW-Zeeman" transitions among Zeeman sub-levels. Exo-energetic transitions of this type are observed with Ne*(3P2) atoms traversing a copper micro-slit grating. They can be used as a tunable beam splitter in an inelastic Fresnel bi-prism atom interferometer.

  3. Monte Carlo Computational Modeling of the Energy Dependence of Atomic Oxygen Undercutting of Protected Polymers

    Science.gov (United States)

    Banks, Bruce A.; Stueber, Thomas J.; Norris, Mary Jo

    1998-01-01

    A Monte Carlo computational model has been developed which simulates atomic oxygen attack of protected polymers at defect sites in the protective coatings. The parameters defining how atomic oxygen interacts with polymers and protective coatings as well as the scattering processes which occur have been optimized to replicate experimental results observed from protected polyimide Kapton on the Long Duration Exposure Facility (LDEF) mission. Computational prediction of atomic oxygen undercutting at defect sites in protective coatings for various arrival energies was investigated. The atomic oxygen undercutting energy dependence predictions enable one to predict mass loss that would occur in low Earth orbit, based on lower energy ground laboratory atomic oxygen beam systems. Results of computational model prediction of undercut cavity size as a function of energy and defect size will be presented to provide insight into expected in-space mass loss of protected polymers with protective coating defects based on lower energy ground laboratory testing.

  4. 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.)

  5. NMR insights into a megadalton-size protein self-assembly

    OpenAIRE

    Chugh, Jeetender; Sharma, Shilpy; Hosur, Ramakrishna V.

    2008-01-01

    Protein self-association is critical to many biological functions. However, atomic-level structural characterization of these assemblies has remained elusive. In this report we present insights into the mechanistic details of the process of self-association of the 136-residue GTPase effector domain (GED) of the endocytic protein dynamin into a megadalton-sized soluble mass. Our approach is based on NMR monitoring of regulated folding and association through Gdn-HCl titration. The results sugg...

  6. Insights into Materials Properties from Ab Initio Theory : Diffusion, Adsorption, Catalysis & Structure

    OpenAIRE

    Blomqvist, Andreas

    2010-01-01

    In this thesis, density functional theory (DFT) calculations and DFT based ab initio molecular dynamics simulations have been employed in order to gain insights into materials properties like diffusion, adsorption, catalysis, and structure. In transition metals, absorbed hydrogen atoms self-trap due to localization of metal d-electrons. The self-trapping state is shown to highly influence hydrogen diffusion in the classical over-barrier jump temperature region. Li diffusion in Li-N-H systems ...

  7. Atomic layer epitaxy

    Science.gov (United States)

    Goodman, Colin H. L.; Pessa, Markus V.

    1986-08-01

    Atomic layer epitaxy (ALE) is not so much a new technique for the preparation of thin films as a novel modification to existing methods of vapor-phase epitaxy, whether physical [e.g., evaporation, at one limit molecular-beam epitaxy (MBE)] or chemical [e.g., chloride epitaxy or metalorganic chemical vapor deposition (MOCVD)]. It is a self-regulatory process which, in its simplest form, produces one complete molecular layer of a compound per operational cycle, with a greater thickness being obtained by repeated cycling. There is no growth rate in ALE as in other crystal growth processes. So far ALE has been applied to rather few materials, but, in principle, it could have a quite general application. It has been used to prepare single-crystal overlayers of CdTe, (Cd,Mn)Te, GaAs and AlAs, a number of polycrystalline films and highly efficient electroluminescent thin-film displays based on ZnS:Mn. It could also offer particular advantages for the preparation of ultrathin films of precisely controlled thickness in the nanometer range and thus may have a special value for growing low-dimensional structures.

  8. 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...

  9. Atomic power's powered atomiser

    International Nuclear Information System (INIS)

    As an extension of its traditional activities the United Kingdom Atomic Energy Authority (UKAEA) has developed a range of products and services. So far one of its most successful ventures has been the licensing of power fluidics technology in the hvac (heating, ventilation and air conditioning) market. Power Fluidics is the control of liquid or gas flows without the use of any moving parts. The UKAEA has developed the vortex amplifier, a control device, which has many potential applications, in which the process flow is throttled and turned down as the control flow is increased. The bistable flow diverter in which a coanda effect diverts the flow down one of two outlets has possible uses in the water industry as well. Another development is a device for controlling fluid droplet size in which a bistable converter has a feedback loop which ensures continuous switching of the flow. By opposing the nozzle outlets, the alternating flows collide in a controlled manner and droplet size can be controlled. (U.K.)

  10. Electron scattering from atoms

    International Nuclear Information System (INIS)

    Methods for electron scattering fall into two main classes : coupled channels methods involve an expansion of the total wave function in target eigenstates; R-matrix methods use a CI expansion for the whole electron-plus-target problem in a finite region of space outside which the electron feels no potential (or only the residual Coulomb potential in the case of charged targets). This problem has no continuum. It has discrete states with arbitrarily-high energies. The wave functions for the finite-range problem are matched to the known external wave functions at the boundary. Experimental data from studies on electron-hydrogen scattering, electron sodium scattering, electron scattering to singlet and triplet states of helium and electron scattering to and from magnesium are reviewed. The coupled-channels-optical model, coupled-channels with ad hoc pseudostates, and R-matrix theory are complete calculations in that no aspects of scattering are omitted, although approximations are of course made. The methods are in at least semi-quantitative agreement with each other where comparison is possible. Experiments in general are in agreement with each other. However for all atoms there are significant disagreements between theory and experiment for small differential cross sections. Total cross sections agree quite well

  11. Atomic structure solution of the complex quasicrystal approximant Al77Rh15Ru8 from electron diffraction data.

    Science.gov (United States)

    Samuha, Shmuel; Mugnaioli, Enrico; Grushko, Benjamin; Kolb, Ute; Meshi, Louisa

    2014-12-01

    The crystal structure of the novel Al77Rh15Ru8 phase (which is an approximant of decagonal quasicrystals) was determined using modern direct methods (MDM) applied to automated electron diffraction tomography (ADT) data. The Al77Rh15Ru8 E-phase is orthorhombic [Pbma, a = 23.40 (5), b = 16.20 (4) and c = 20.00 (5) Å] and has one of the most complicated intermetallic structures solved solely by electron diffraction methods. Its structural model consists of 78 unique atomic positions in the unit cell (19 Rh/Ru and 59 Al). Precession electron diffraction (PED) patterns and high-resolution electron microscopy (HRTEM) images were used for the validation of the proposed atomic model. The structure of the E-phase is described using hierarchical packing of polyhedra and a single type of tiling in the form of a parallelogram. Based on this description, the structure of the E-phase is compared with that of the ε6-phase formed in Al-Rh-Ru at close compositions. PMID:25449623

  12. Bohmian picture of Rydberg atoms

    Indian Academy of Sciences (India)

    Partha Ghose; Manoj K Samal; Animesh Datta

    2002-08-01

    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.

  13. Hot tube atomic absorption spectrochemistry.

    Science.gov (United States)

    Woodriff, R; Stone, R W

    1968-07-01

    A small, commercially available atomic absorption instrument is used with a heated graphite tube for the atomic absorption analysis of liquid and solid silver samples. Operating conditions of the furnace are described and a sensitivity of about 5 ng of silver is reported. PMID:20068797

  14. Fiber cavities for atom chips

    OpenAIRE

    Klappauf, B.G.; Horak, P.; Kazansky, P. G.

    2003-01-01

    We present experimental realizations of several micro-cavities, constructed from standard fiber optic components, which meet the theoretical criteria for single atom detection from laser-cooled samples. We discuss integration of these cavities into state-of-the-art 'atom chips'.

  15. Multiphoton ionization of polarized atoms

    International Nuclear Information System (INIS)

    A theory is derived for the multiphoton ionization of polarized atoms. The angular distributions of the differential and total ionization probabilities are studied for various polarizations of the electromagnetic radiation. The circular dichroism is also studied. The multiphoton ionization of oriented s-state atoms near a resonance is studied separately. Some relevant experiments which might be carried out are discussed

  16. The atomic energy basic law

    International Nuclear Information System (INIS)

    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.)

  17. Atomic Energy Authority Act 1954

    International Nuclear Information System (INIS)

    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)

  18. Atomic matching across internal interfaces

    International Nuclear Information System (INIS)

    The atomic structure of internal interfaces in dense-packed systems has been investigated by high-resolution electron microscopy (HREM). Similarities between the atomic relaxations in heterophase interfaces and certain large-angle grain boundaries have been observed. In both types of interfaces localization of misfit leads to regions of good atomic matching within the interface separated by misfit dislocation-like defects. It appears that, whenever possible, the GB structures assume configurations in which the atomic coordination is not too much different from the ideal lattice. It is suggested that these kinds of relaxations primarily occur whenever the translational periods along the GB are large or when the interatomic distances are incommensurate. Incorporation of low index planes into the GB appears to lead to preferred, i.e. low energy structures, that can be quite dense with good atomic matching across a large fraction of the interface

  19. Polarization effects in atomic transitions

    International Nuclear Information System (INIS)

    In this review an attempt is made to provide a unified description of various types of atomic core polarization effects in the free-free, free-bound and bound-bound transitions of charged particles in the field of a multielectron atom. For all types of transitions, both classical and quantum models are used for describing the scattering and energy-re-emission of a particle interacting with the atomic core. Experimental and theoretical results are given for the oscillator strengths of atoms and multiply charged ions; polarization phenomena associated with the photoeffect; a new polarization recombination channel; and the Bremsstrahlung of electrons and relativistic and heavy particles on complex atoms and ions

  20. First insights into disassembled "evapotranspiration"

    Science.gov (United States)

    Chormański, Jarosław; Kleniewska, Małgorzata; Berezowski, Tomasz; Szporak-Wasilewska, Sylwia; Okruszko, Tomasz; Szatyłowicz, Jan; Batelaan, Okke

    2015-04-01

    In this work we present an initial data analysis obtained from a complex tool for measuring water fluxes in wetland ecosystems. The tool was designed to quantify processes related to interception storage on plants leafs. The measurements are conducted by combining readings from various instruments, including: eddy covariance tower (EC), field spectrometer, SapFlow system, rain gauges above and under canopy, soil moisture probes and other. The idea of this set-up is to provide continuous measurement of overall water flux from the ecosystem (EC tower), intercepted water volume and timing (field spectrometers), through-fall (rain gauges above and under canopy), transpiration (SapFlow), evaporation and soil moisture (soil moisture probes). Disassembling the water flux to the above components allows giving more insight to the interception related processes and differentiates them fromthe total evapotranspiration. The measurements are conducted in the Upper Biebrza Basin (NE Poland). The study area is part of the valley and is covered by peat soils (mainly peat moss with the exception of areas near the river) and receives no inundations waters of the Biebrza. The plant community of Agrostietum-Carici caninae has a dominant share here creating an up to 0.6 km wide belt along the river. The area is covered also by Caricion lasiocarpae as well as meadows and pastures Molinio-Arrhenatheretea, Phragmitetum communis. Sedges form a hummock pattern characteristic for the sedge communities in natural river valleys with wetland vegetation. The main result of the measurement set-up will be the analyzed characteristics and dynamics of interception storage for sedge ecosystems and a developed methodology for interception monitoring by use spectral reflectance technique. This will give a new insight to processes of evapotranspiration in wetlands and its component transpiration, evaporation from interception and evaporation from soil. Moreover, other important results of this project

  1. AC Zeeman potentials for atom chip-based ultracold atoms

    Science.gov (United States)

    Fancher, Charles; Pyle, Andrew; Ziltz, Austin; Aubin, Seth

    2015-05-01

    We present experimental and theoretical progress on using the AC Zeeman force produced by microwave magnetic near-fields from an atom chip to manipulate and eventually trap ultracold atoms. These AC Zeeman potentials are inherently spin-dependent and can be used to apply qualitatively different potentials to different spin states simultaneously. Furthermore, AC Zeeman traps are compatible with the large DC magnetic fields necessary for accessing Feshbach resonances. Applications include spin-dependent trapped atom interferometry and experiments in 1D many-body physics. Initial experiments and results are geared towards observing the bipolar detuning-dependent nature of the AC Zeeman force at 6.8 GHz with ultracold 87Rb atoms trapped in the vicinity of an atom chip. Experimental work is also underway towards working with potassium isotopes at frequencies of 1 GHz and below. Theoretical work is focused on atom chip designs for AC Zeeman traps produced by magnetic near-fields, while also incorporating the effect of the related electric near-fields. Electromagnetic simulations of atom chip circuits are used for mapping microwave propagation in on-chip transmission line structures, accounting for the skin effect, and guiding impedance matching.

  2. 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

    Mitochondrial membranes are unique in many ways. Unlike other cellular membranes, they are comprised of two membranes instead of just one, and cardiolipins, one of the abundant lipid species in mitochondrial membranes, are not found in significant amounts elsewhere in the cell. Among other aspects......), phosphatidylcholines (PCs), and phosphatidylethanolamines (PEs). For comparison, we also consider pure one-component bilayers and mixed PC-PE, PC-CL, and PE-CL membranes. We find that the influence of CLs on membrane properties depends strongly on membrane composition. This is highlighted by studies of the stability...... of CL-containing membranes, which indicate that the interactions of CL in ternary lipid bilayers cannot be deduced from the corresponding ones in binary membranes. Moreover, while the membrane properties in the hydrocarbon region are only weakly affected by CLs, the changes at the membrane-water...

  3. Molecular insights into diphenylalanine nanotube assembly: all-atom simulations of oligomerization.

    Science.gov (United States)

    Jeon, Joohyun; Mills, Carolyn E; Shell, M Scott

    2013-04-18

    Self-assembling peptides represent a growing class of inexpensive, environmentally benign, nanostructured materials. In particular, diphenylalanine (FF) self-assembles into nanotubes with remarkable strength and thermal stability that have found use in a wide variety of applications, including as sacrificial templates and scaffolds for structuring inorganic materials and as interfacial "nanoforests" for superhydrophobic surfaces and high-performance supercapacitors and biosensors. However, little is known about the assembly mechanisms of FF nanotubes or the forces underlying their stability. Here, we perform a variety of molecular dynamics simulations on both zwitterionic and capped (uncharged) versions of the FF peptide to understand the early stages of self-assembly. We compare these results to simulations of the proposed nanotube X-ray crystal structure. When comparing the zwitterionic and uncharged FF peptides, we find that, while electrostatic interactions steer the former into more ordered dimers and trimers, the hydrophobic side chain interactions play a strong role in determining the structures of larger oligomers. Simulations of the crystal structure fragment also suggest that the strongest interactions occur between side chains, not between the charged termini that form salt bridges. We conclude that the amphiphilic nature of FF is key to understanding its self-assembly, and that the early precursors to nanotube structures are likely to involve substantial hydrophobic clustering, rather than hexamer ring motifs as has been previously suggested. PMID:23521630

  4. Mining Login Data for Actionable Student Insight

    Science.gov (United States)

    Agnihotri, Lalitha; Aghababyan, Ani; Mojarad, Shirin; Riedesel, Mark; Essa, Alfred

    2015-01-01

    Student login data is a key resource for gaining insight into their learning experience. However, the scale and the complexity of this data necessitate a thorough exploration to identify potential actionable insights, thus rendering it less valuable compared to student achievement data. To compensate for the underestimation of login data…

  5. Obsessive Compulsive Disorder with Poor Insight

    Directory of Open Access Journals (Sweden)

    Serkut Bulut

    2014-06-01

    Full Text Available Obsessive-compulsive disorder is a mental disorder that may cause severe disability. Insight in obsessive-compulsive disorder has been an issue of debate since the disorder was described for the first time. Formerly, obsessive-compulsive disorder was regarded as one of the neurotic disorders and patients were supposed to find their symptoms as totally senseless and exaggerated. However, the idea that obsessions have to be regarded egodystonic has changed recently. Firstly in the Diagnostic and Statistical Manual of Mental Disorders 4th edition (DSM-IV, the term \\"with poor insight and rdquo; was used as a specifier for obsessive-compulsive disorder. Obsessive-compulsive disorder with low or no insight may differ from obsessive-compulsive disorder with good insight in terms of sociodemographic, clinical and treatment features. Along with types of obsessions, the levels of insight are subject to change. Obsessive-compulsive disorder with poor insight can either be a subtype with different features or a severe form of Obsessive-compulsive disorder. Along with DSM-5 insight in obsessive-compulsive disorder is no longer classified as absent or present. Insight in obsessive-compulsive disorder needs to be conceptualized as a spectrum or continuity. [Psikiyatride Guncel Yaklasimlar - Current Approaches in Psychiatry 2014; 6(2.000: 126-141

  6. Insight Projects: PATHway and Replay overview

    OpenAIRE

    Monaghan, David; Walsh, Deirdre; Ahmadi, Amin

    2015-01-01

    An overview of current projects within Insight presented during the Insight Summer Research Event, including PATHway: Technology enabled behavioural change as a pathway towards better self-management of CVD and RePLAY: Digitally Capturing Unique skills in European Traditional Sports and Games.

  7. 2013 insight contexts the imaginative landscape

    CERN Document Server

    2012-01-01

    Insight Contexts 2013 are especially designed to develop students' thinking and writing skills for Area of Study 2: Creating and Presenting. A rich resource of information and ideas on the Context and each of the selected texts, Insight Contexts also provides students with a variety of writing tips and strategies for developing excellent Context responses.

  8. Course of insight in manic episode

    Directory of Open Access Journals (Sweden)

    A Kumar

    2013-01-01

    Full Text Available Background: Insight is an important factor associated with non compliance and poor outcome. Poor level of insight has been described as a characteristic in patients with acute bipolar disorder with more unawareness in social consequences with increasing severity in manic episode. Aim: Main aim of study was to see the baseline and longitudinal relationship between dimensions of insight with improvement in psychopathology. Setting and Design: Forty four patients diagnosed with mania, were selected from an inpatient setting at Institute of Mental Health and Hospital, Agra with mean age of 31.07(±9.00 years. They were assessed at base line and were followed up weekly or psychopathology and insight. Materials and Methods: The Young′s mania rating scale for psychopathology and insight was assessed on three dimensions of SUMD. Results: Twenty five patients eventually completed the study. There was a positive correlation with global insight and with psychopathology consistent in longitudinal follow-up (P<0.05, but not correlating for awareness for achieved effect of medication and social consequences. Linear regression showed a positive relationship at the first and second week of assessment of SUMD and YMRS scores (P=0.001; 0.019. Conclusion: Improvement in insight is graded in a manic episode as compared to psychopathology. There is slower improvement in awareness of social consequences of mental disorder. It means that improvement in psychopathology may not necessarily indicate remission and need further supervision to improve insight and hence monitoring.

  9. Trapping atoms on a transparent permanent-magnet atom chip

    CERN Document Server

    Shevchenko, A; Jaakkola, A; Kaivola, M; Lindvall, T; Pfau, T; Tittonen, I

    2006-01-01

    We describe experiments on trapping of atoms in microscopic magneto-optical traps on an optically transparent permanent-magnet atom chip. The chip is made of magnetically hard ferrite-garnet material deposited on a dielectric substrate. The confining magnetic fields are produced by miniature magnetized patterns recorded in the film by magneto-optical techniques. We trap Rb atoms on these structures by applying three crossed pairs of counter-propagating laser beams in the conventional magneto-optical trapping (MOT) geometry. We demonstrate the flexibility of the concept in creation and in-situ modification of the trapping geometries through several experiments.

  10. 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

  11. Manipulating nanoscale atom-atom interactions with cavity QED

    CERN Document Server

    Pal, Arpita; Deb, Bimalendu

    2016-01-01

    We theoretically explore manipulation of interactions between excited and ground state atoms at nanoscale separations by cavity quantum electrodynamics (CQED). We develop an adiabatic molecular dressed state formalism and show that it is possible to generate Fano-Feshbach resonances between ground and long-lived excited-state atoms inside a cavity. The resonances are shown to arise due to non-adiabatic coupling near a pseudo-crossing between the dressed state potentials. We illustrate our results with a model study using fermionic $^{171}$Yb atoms in a two-modal cavity. Our study is important for manipulation of interatomic interactions at low energy by cavity field.

  12. Iron and cancer: recent insights.

    Science.gov (United States)

    Manz, David H; Blanchette, Nicole L; Paul, Bibbin T; Torti, Frank M; Torti, Suzy V

    2016-03-01

    Iron is an essential dietary element. However, the ability of iron to cycle between oxidized and reduced forms also renders it capable of contributing to free radical formation, which can have deleterious effects, including promutagenic effects that can potentiate tumor formation. Dysregulation of iron metabolism can increase cancer risk and promote tumor growth. Cancer cells exhibit an enhanced dependence on iron relative to their normal counterparts, a phenomenon we have termed iron addiction. Work conducted in the past few years has revealed new cellular processes and mechanisms that deepen our understanding of the link between iron and cancer. Control of iron efflux through the combined action of ferroportin, an iron efflux pump, and its regulator hepcidin appears to play an important role in tumorigenesis. Ferroptosis is a form of iron-dependent cell death involving the production of reactive oxygen species. Specific mechanisms involved in ferroptosis, including depletion of glutathione and inhibition of glutathione peroxidase 4, have been uncovered. Ferritinophagy is a newly identified mechanism for degradation of the iron storage protein ferritin. Perturbations of mechanisms that control transcripts encoding proteins that regulate iron have been observed in cancer cells, including differences in miRNA, methylation, and acetylation. These new insights may ultimately provide new therapeutic opportunities for treating cancer. PMID:26890363

  13. Unlocking the atom

    International Nuclear Information System (INIS)

    Nuclear power has become the subject of widespread and intense public discussion. The book details the history of nuclear power in Great Britain, and provides clear explanations of the technology by which the energy released in nuclear fission is harnessed and converted into usable power. After outlining the properties of the atomic nucleus and the early stages in the discovery of nuclear energy, a survey is presented of the British nuclear programme which began when the first power station was commissioned at Calder Hall in 1956. The different models of nuclear reactor developed in Britain are described, in each case with the help of diagrams. These include the Magnox designs, which have been in use for some years, the more recent advanced gas-cooled and sodium-cooled reactors, and foreign systems such as the American pressurised- and boiling-water reactors. The important distinctions between thermal and fast reactors are also explained, as are reactor designs which may be able to exploit fusion power. The nuclear fuel cycle is followed closely, describing the stages by which uranium is mined and processed into fuel, involving chemical separation and isotope enrichment. Then, once the fuel has been consumed in the reactor, it must be safely removed, its by-products extracted, especially highly toxic plutonium, and its wastes treated and stored. Comprehensive safety precautions are vital in this as in every stage of the nuclear cycle, and particular attention is paid to them throughout the book: in a chapter devoted to safety consideration is given to the ramifications of the accident in 1979 at the Three Mile Island reactor in the United States. Detailed comparison is made between nuclear and other sources of energy, and the wider applications of nuclear energy are assessed. Finally, some of the social questions raised by the use of nuclear power, and also the future of this most controversial of energy sources, are discussed. (author)

  14. Atomic energy review

    International Nuclear Information System (INIS)

    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

  15. Nanoindentation of gold nanorods with an atomic force microscope

    Science.gov (United States)

    Reischl, B.; Kuronen, A.; Nordlund, K.

    2014-12-01

    The atomic force microscope (AFM) can be used to measure mechanical properties of nanoscale objects, which are too small to be studied using a conventional nanoindenter. The contact mechanics at such small scales, in proximity of free surfaces, deviate substantially from simple continuum models. We present results from atomistic computer simulations of the indentation of gold nanorods using a diamond AFM tip and give insight in the atomic scale processes, involving creation and migration of dislocations, leading to the plastic deformation of the sample under load, and explain the force-distance curves observed for different tip apex radii of curvature, as well as different crystallographic structure and orientation of the gold nanorod samples.

  16. Atomic picture of elastic deformation in a metallic glass

    International Nuclear Information System (INIS)

    The tensile behavior of a Ni60Nb40 metallic glass (MG) has been studied by using ab initio density functional theory (DFT) calculation with a large cell containing 1024 atoms (614 Ni and 410 Nb). We provide insight into how a super elastic limit can be achieved in a MG. Spatially inhomogeneous responses of single atoms and also major polyhedra are found to change greatly with increasing external stress when the strain is over 2%, causing the intrinsically viscoelastic behavior. We uncover the origin of the observed super elastic strain limit under tension (including linear and viscoelastic strains) in small-sized MG samples, mainly caused by inhomogeneous distribution of excess volumes in the form of newly formed subatomic cavities

  17. Characteristics of integrated magneto-optical traps for atom chips

    CERN Document Server

    Pollock, S; Laliotis, A; Ramirez-Martinez, F; Hinds, E A

    2011-01-01

    We investigate the operation of pyramidal magneto-optical traps (MOTs) microfabricated in silicon. Measurements of the loading and loss rates give insight into the role of the nearby surface in the MOT dynamics. Studies of the fluorescence versus laser frequency and intensity allow us to develop a simple theory of operation. The number of $^{85}$Rb atoms trapped in the pyramid is approximately $L^6$, where $L \\lesssim 6$ is the size in mm. This follows quite naturally from the relation between capture velocity and size and differs from the $L^{3.6}$ often used to describe larger MOTs. Our results constitute substantial progress towards fully integrated atomic physics experiments and devices.

  18. Principles for structure analysis of carbon nanotubes by HRTEM

    International Nuclear Information System (INIS)

    An efficient algorithm is derived for generating all possible seamless carbon nanotube structure models. This makes use of multijugate helical lattices, a concept borrowed from some biological structures. Principles for helicity and structure analysis of carbon nanotubes using high-resolution electron microscopy and image processing techniques are then developed. Applicability is tested on experimentally obtained images. The limitations of this approach are examined. Provided the tubules contain less than three to five layers the individual component layer helicities and the order of assembly may be obtained from the high-resolution many-beam bright - and dark-field image reconstructions. 16 refs., 11 figs

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

    OpenAIRE

    Gutiérrez-González, C.F.; Agouram, S.; Torrecillas, Ramón; J. S. MOYA; Lopez-Esteban, S.

    2012-01-01

    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 showe...

  20. Structural transformation of vapor grown carbon nanofibers studied by HRTEM

    International Nuclear Information System (INIS)

    Vapor grown carbon nanofibers have been extensively manufactured and investigated in recent years. In this study commercially available vapor grown carbon nanofibers subjected to different processing and post processing conditions were studied employing high resolution TEM images. The analysis showed that the fibers consist primarily of conical nanofibers, but can contain a significant amount of bamboo nanofibers. Most conical nanofibers were found to consist of an ordered inner layer and a disordered outer layer, with the cone angle distribution of the inner layers indicating that these cannot have a stacked cone structure but are compatible with a cone-helix structure. Fibers that have been heat treated to temperatures above 1,500 oC undergo a structural transformation with the ordered inner layers changing from a cone-helix structure to a highly ordered multiwall stacked cone structure. The bamboo nanofibers were found to have a tapered multiwall nanotube structure for the wall and a multishell fullerene structure for the cap of each segment, surrounded by a disordered outer layer. When these fibers are heat treated the disordered outer layers transform to an ordered multiwall nanotube structure and merge with the wall of each segment. The end caps of each segment transform from a smooth multiwall fullerene structure to one consisting of disjointed graphene planes. A reaction-diffusion mechanism is proposed to explain the growth and structure of the bamboo nanofibers.

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

    DEFF Research Database (Denmark)

    Kling, Jens; Vestergaard, Jacob Schack; Dahl, Anders Bjorholm; Hansen, Thomas Willum; Larsen, Rasmus; Wagner, Jakob Birkedal

    structure in the image. The centers of the C-hexagons are displayed as nodes. To segment the image into “pure” and “impure” regions, like areas with residual amorphous contamination or defects e.g. holes, a sliding window approach is used. The magnitude of the Fourier transformation within a window is...... tensor B-splines is employed, which is deformed by matching model grid points with the C-hexagon centers. Dependent on the Cs and defocus-settings during microscopy these centers appear either dark or bright. One ends up with a deformed hexagonal tessellation, which can easily be transformed into a...... length scale, and at the same time lattice deformations can be visualized. The method will be refined to facilitate the detection of larger defects like holes and the determination of the edge terminations....

  2. Knochenablation mit fasergeführtem XeCl-Excimerlaserstrahl

    OpenAIRE

    Jahn, Renate; Dressel, Martin; Langendorff, Hans-Ulrich; Neu, Walter; Jungbluth, Karl-Heinz

    1991-01-01

    Eine neue Lasertechnik erweckt durch ihr "athermisches" Abtragungsprinzip nun auch das Interesse der Unfallchirurgen. Mit hoher Schnittqualität und präzisem Bohren bei industriellen Fertigungsverfahren zeigte der Excimerlaser andere Wege in der Oberflächenbearbeitung von Hartmaterialien (Glas, Keramik, Diamant) auf.Die Materialabtragung erfolgt nicht mehr durch ausschließlich photothermische Wirkung, sondern indem auch molekulare Bindungen aufgrund der hohen Photonenenergie des Lasers aufgebr...

  3. Bohrungen am Knochen mit fasergeführtem Excimerlaserstrahl

    OpenAIRE

    Jahn, Renate; Dressel, Martin; Fabian, Heinz; Klein, Karl-Friedrich; Langendorff, Hans-Ulrich; Neu, Walter; Jungbluth, Karl-Heinz

    1990-01-01

    Zur Ermittlung einer optimalen Parametereinstellung des Excimerlasers für die Bearbeitung von Knochengewebe, testeten wir bei drei unterschiedlichen Impulslängen den Einfluß von Austrittsenergie und Repetitionsrate auf die Ablationstiefe.

  4. Atomic stabilization in superintense laser fields

    International Nuclear Information System (INIS)

    Atomic stabilization is a highlight of superintense laser-atom physics. A wealth of information has been gathered on it; established physical concepts have been revised in the process; points of contention have been debated. Recent technological breakthroughs are opening exciting perspectives of experimental study. With this in mind, we present a comprehensive overview of the phenomenon. We discuss the two forms of atomic stabilization identified theoretically. The first one, 'quasistationary (adiabatic) stabilization' (QS), refers to the limiting case of plane-wave monochromatic radiation. QS characterizes the fact that ionization rates, as calculated from single-state Floquet theory, decrease with intensity (possibly in an oscillatory manner) at high values of the field. We present predictions for QS from various forms of Floquet theory: high frequency (that has led to its discovery and offers the best physical insight), complex scaling, Sturmian, radiative close coupling and R-matrix. These predictions all agree quantitatively, and high-accuracy numerical results have been obtained for hydrogen. Predictions from non-Floquet theories are also discussed. Thereafter, we analyse the physical origin of QS. The alternative form of stabilization, 'dynamic stabilization' (DS), is presented next. This expresses the fact that the ionization probability at the end of a laser pulse of fixed shape and duration does not approach unity as the peak intensity is increased, but either starts decreasing with the intensity (possibly in an oscillatory manner), or flattens out at a value smaller than unity. We review the extensive research done on one-dimensional models, that has provided valuable insights into the phenomenon; two- and three-dimensional models are also considered. Full three-dimensional Coulomb calculations have encountered severe numerical handicaps in the past, and it is only recently that a comprehensive mapping of DS could be made for hydrogen. An adiabatic

  5. Schizophrenia - Insight, Depression: A Correlation Study

    Directory of Open Access Journals (Sweden)

    Prasanth Ampalam

    2012-01-01

    Full Text Available Background: Schizophrenia is one of the severe forms of mental illness which demands enormous personal and economical costs. Recent years have attracted considerable interest in the dual problem of depression in schizophrenia and its relation to insight. Most clinicians believe that poor insight in patients with schizophrenia, though problematic for treatment adherence, may be protective with respect to suicide. The assumption is that patients who do not believe that they are ill are less likely to be suicidal. Alternatively, those patients with schizophrenia who recognize and acknowledge the illness will be more of a suicidal nature. Aim of the Study: The aim of the study is to find out the correlation between insight and depression in schizophrenic population. Materials and Methods: This study is a cross-sectional, single-centred, correlation study done in a total of 60 subjects. Inclusion Criteria - Subjects between 20-60 years, who were diagnosed to have schizophrenia as per International clasification of diseases-10 and who have given written consent to participate in the study. Exclusion Criteria - Subjects who have other diagnosis such as mood disorder, schizoaffective disorder, mental retardation, epilepsy or detectable organic disease and co morbid substance abuse are excluded from the study. Schizophrenics who have acute exacerbation are also excluded. Instruments - For insight assessment, schedule for assessment of insight, a three item rating scale, is used. For depressive symptoms assessment a nine item rating scale, Calgary depression rating scale, is administrated. Results: Insight and depression are strongly correlated in schizophrenic population with a Pearson correlation coefficient of 0.758. The correlation between insight and depression is high in subjects with less duration of illness. Conclusion: Better insight was significantly correlated with lower mood. In addition, it suggests that poor insight may protect against

  6. An atom-by-atom assembler of defect-free arbitrary 2d atomic arrays

    CERN Document Server

    Barredo, Daniel; Lienhard, Vincent; Lahaye, Thierry; Browaeys, Antoine

    2016-01-01

    Large arrays of individually controlled atoms trapped in optical tweezers are a very promising platform for quantum engineering applications. However, to date, only disordered arrays have been demonstrated, due to the non-deterministic loading of the traps. Here, we demonstrate the preparation of fully loaded, two-dimensional arrays of up to 50 microtraps each containing a single atom, and arranged in arbitrary geometries. Starting from initially larger, half-filled matrices of randomly loaded traps, we obtain user-defined target arrays at unit filling. This is achieved with a real-time control system and a moving optical tweezers that performs a sequence of rapid atom moves depending on the initial distribution of the atoms in the arrays. These results open exciting prospects for quantum engineering with neutral atoms in tunable geometries.

  7. Atomization of volatile compounds for atomic absorption and atomic fluorescence spectrometry: On the way towards the ideal atomizer

    International Nuclear Information System (INIS)

    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

  8. A linear atomic quantum coupler

    Science.gov (United States)

    El-Orany, Faisal A. A.; Wahiddin, M. R. B.

    2010-04-01

    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.

  9. Hybrid atom-membrane optomechanics

    Directory of Open Access Journals (Sweden)

    Korppi Maria

    2013-08-01

    Full Text Available We report on the realization of a hybrid optomechanical system in which ultracold atoms are coupled to a micromechanical membrane. The atoms are trapped in the intensity maxima of an optical standing wave formed by retroreflection of a laser beam from the membrane surface. Vibrations of the membrane displace the standing wave, thus coupling to the center-of-mass motion of the atomic ensemble. Conversely, atoms imprint their motion onto the laser light, thereby modulating the radiation pressure force on the membrane. In this way, the laser light mediates a long-distance coherent coupling between the two systems. When the trap frequency of the atoms is matched to the membrane frequency, we observe resonant energy transfer. Moreover, we demonstrate sympathetic damping of the membrane motion by coupling it to laser-cooled atoms. Theoretical investigations show that the coupling strength can be considerably enhanced by placing the membrane inside an optical cavity. This could lead to quantum coherent coupling and ground-state cooling of the membrane via a distant atomic ensemble.

  10. A linear atomic quantum coupler

    International Nuclear Information System (INIS)

    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.

  11. Microchip-Based Trapped-Atom Clocks

    OpenAIRE

    Vuletic, Vladan; Leroux, Ian D.; Schleier-Smith, Monika H.

    2011-01-01

    This is a chapter of a recently published book entitled Atom Chips, edited by Jakob Reichel and Vladan Vuletic. The contents of this chapter include: Basic Principles; Atomic-Fountain versus Trapped-Atom Clocks; Optical-Transition Clocks versus Microwave Clocks; Clocks with Magnetically Trapped Atoms--Fundamental Limits and Experimental Demonstrations; Readout in Trapped-Atom Clocks; and Spin Squeezing.

  12. Entanglement of Two Atoms using Rydberg Blockade

    OpenAIRE

    Walker, Thad G.; Saffman, Mark

    2012-01-01

    Over the past few years we have built an apparatus to demonstrate the entanglement of neutral Rb atoms at optically resolvable distances using the strong interactions between Rydberg atoms. Here we review the basic physics involved in this process: loading of single atoms into individual traps, state initialization, state readout, single atom rotations, blockade-mediated manipulation of Rydberg atoms, and demonstration of entanglement.

  13. Recognizing nitrogen dopant atoms in graphene using atomic force microscopy

    Science.gov (United States)

    van der Heijden, Nadine J.; Smith, Daniël; Calogero, Gaetano; Koster, Rik S.; Vanmaekelbergh, Daniel; van Huis, Marijn A.; Swart, Ingmar

    2016-06-01

    Doping graphene by heteroatoms such as nitrogen presents an attractive route to control the position of the Fermi level in the material. We prepared N-doped graphene on Cu(111) and Ir(111) surfaces via chemical vapor deposition of two different molecules. Using scanning tunneling microscopy images as a benchmark, we show that the position of the dopant atoms can be determined using atomic force microscopy. Specifically, the frequency shift-distance curves Δ f (z ) acquired above a N atom are significantly different from the curves measured over a C atom. Similar behavior was found for N-doped graphene on Cu(111) and Ir(111). The results are corroborated by density functional theory calculations employing a van der Waals functional.

  14. AtomChips: mesoscopic physics with ultracold atoms

    International Nuclear Information System (INIS)

    Full text: Miniaturization and integration of atom-optical components on atom chips allow coherent manipulation of matter waves on the quantum level by using high spatial resolution electro magnetic potentials from structures on the atom chip or by employing adiabatic radio frequency (RF) or micro wave (MW) potentials. Bose-Einstein condensates (BECs) on these AtomChips can be used for many different tasks. These range from measuring magnetic and electric fields with unprecedented sensitivity by observing the density modulations in trapped highly elongated 1d BECs, to fundamental studies of the universal properties in low dimensional systems like non equilibrium dynamics and coherence decay in one-dimensional super fluids. The talk will give an overview of the recent advances and experiments. (author)

  15. Rydberg atoms in ultracold plasmas

    Science.gov (United States)

    Rolston, Steven

    2009-05-01

    Ultracold plasmas are formed through the photoionization of laser-cooled atoms, or spontaneous ionization of a dense cloud of Rydberg atoms or now molecules[1]. Ultracold plasmas are inherently metastable, as the ions and electrons would be in a lower energy state bound together as atoms. The dominant process of atom formation in these plasmas is three-body recombination, a collision between two electrons and an ion that leads to the formation of a Rydberg atom. This collisional process is not only important in determining the lifetime and density of the plasma, but is also critical in determining the time evolution of the temperature. The formation of the Rydberg atoms is accompanied by an increase in electron energy for the extra electron in the collision, and is a source of heating in these plasmas. Classical three-body recombination theory scales as T-9/2, and thus as a plasma cools due to a process such as adiabatic expansion, recombination-induced heating turns on, limiting the temperature [2]. The Rydberg atoms formed live in the plasma and contribute to the temperature dynamics, as collisions with plasma electrons can change the principal quantum number of the Rydberg atom, driving it to more tightly bound states (a source of plasma heating) or to higher states (a source of plasma cooling). If the plasma is cold and dense enough to be strongly coupled, classical three-body recombination theory breaks down. Recent theoretical work [3] suggests that the rate limits as the plasma gets strongly coupled. I will review the role of Rydberg atoms in ultracold plasmas and prospects for probing Rydberg collisions in the strongly coupled environment. [4pt] [1] J. P. Morrison, et al., Phys. Rev. Lett. 101, 205005 (2008 [0pt] [2] R. S. Fletcher, X. Zhang, and S. L. Rolston, Phys. Rev. Lett. 99, 145001 (2007 [0pt] [3] T. Pohl, private communication.

  16. Atomic Data: Division XII / Commission 14 / Working Group Atomic Data

    OpenAIRE

    Nave, Gillian; Wahlgren, Glenn M.; Fuhr, Jeffrey R.

    2012-01-01

    This report summarizes laboratory measurements of atomic wavelengths, energy levels, hyperfine and isotope structure, energy level lifetimes, and oscillator strengths. Theoretical calculations of lifetimes and oscillator strengths are also included. The bibliography is limited to species of astrophysical interest. Compilations of atomic data and internet databases are also included. Papers are listed in the bibliography in alphabetical order, with a reference number in the text.

  17. Atomic Data: Division B / Commission 14 / Working Group Atomic Data

    OpenAIRE

    Nave, Gillian; Nahar, Sultana; Zhao, Gang

    2015-01-01

    This report summarizes laboratory measurements of atomic wavelengths, energy levels, hyperfine and isotope structure, energy level lifetimes, and oscillator strengths. Theoretical calculations of lifetimes and oscillator strengths are also included. The bibliography is limited to species of astrophysical interest. Compilations of atomic data and internet databases are also included. Papers are listed in the bibliography in alphabetical order, with a reference number in the text. Comprehensive...

  18. Atom gratings produced by large angle atom beam splitters

    OpenAIRE

    Dubetsky, B.; Berman, P. R.

    2001-01-01

    An asymptotic theory of atom scattering by large amplitude periodic potentials is developed in the Raman-Nath approximation. The atom grating profile arising after scattering is evaluated in the Fresnel zone for triangular, sinusoidal, magneto-optical, and bichromatic field potentials. It is shown that, owing to the scattering in these potentials, two \\QTR{em}{groups} of momentum states are produced rather than two distinct momentum components. The corresponding spatial density profile is cal...

  19. Scanning probe microscopy of oxide surfaces: atomic structure and properties

    International Nuclear Information System (INIS)

    The intersection of two fields, oxide surface science and scanning probe microscopy (SPM), has yielded considerable insight on atomic processes at surfaces. Oxide surfaces, especially those containing transition metals, offer a rich variety of structures and localized physical phenomena that are exploited in a wide range of applications. Nonlinear optics, superconductivity, ferroelectricity and chemical catalytic activity are but a few. Furthermore, the challenges and solutions associated with the chemistry of these surfaces and particularly the solutions to these problems have led to important understanding of tip-surface interactions that can inform SPM studies of all materials. Here, the development of understanding of the model systems TiO2 and SrTiO3 are considered in detail, to demonstrate the role of nonstoichiometry in surface structure evolution and the approach to interpreting structure at the atomic level. Then a combination of scanning tunneling microscopy, noncontact atomic force microscopy and theory are applied to a variety of oxide systems including Al2O3, NiO, ferroelectric BaTiO3, tungstates and molybdates. Recently developed sophisticated probes of local properties include spin-polarized tunneling, Fourier mapping of charge density waves, band gap mapping of superconductors and ultra fast imaging of atomic diffusion. The impact of these studies on our understanding of the behavior of oxides and of tip-surface interactions is summarized

  20. High Fidelity Simulation of Primary Atomization in Diesel Engine Sprays

    Science.gov (United States)

    Ivey, Christopher; Bravo, Luis; Kim, Dokyun

    2014-11-01

    A high-fidelity numerical simulation of jet breakup and spray formation from a complex diesel fuel injector at ambient conditions has been performed. A full understanding of the primary atomization process in fuel injection of diesel has not been achieved for several reasons including the difficulties accessing the optically dense region. Due to the recent advances in numerical methods and computing resources, high fidelity simulations of atomizing flows are becoming available to provide new insights of the process. In the present study, an unstructured un-split Volume-of-Fluid (VoF) method coupled to a stochastic Lagrangian spray model is employed to simulate the atomization process. A common rail fuel injector is simulated by using a nozzle geometry available through the Engine Combustion Network. The working conditions correspond to a single orifice (90 μm) JP-8 fueled injector operating at an injection pressure of 90 bar, ambient condition at 29 bar, 300 K filled with 100% nitrogen with Rel = 16,071, Wel = 75,334 setting the spray in the full atomization mode. The experimental dataset from Army Research Lab is used for validation in terms of spray global parameters and local droplet distributions. The quantitative comparison will be presented and discussed. Supported by Oak Ridge Associated Universities and the Army Research Laboratory.

  1. Study on laser atomic spectroscopy

    International Nuclear Information System (INIS)

    Laser atomic spectroscopic study on actinium element has been performed in many areas of spectroscopy. The study on characteristic of atomic vapor has been proceeded for copper atom and the spatial density distribution of copper vapor is measured. This experimental data has been compared with the theoretically calculated data. In spectroscopic experiment, the first and second excited states for actinium element are identified and the most efficient ionization scheme for actinium element is identified. In addition, the corrosion problem for filament material due to the heating of the actinium element has been studied. (Author)

  2. 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

  3. Atomic Data for Stellar Nucleosynthesis

    Science.gov (United States)

    Sneden, Christopher Alan; Lawler, James E.; Den Hartog, Elizabeth A.; Wood, Michael

    2015-08-01

    Stellar chemical composition analyses can only yield reliable abundances if the atomic transition parameters are accurately determined. During the last couple of decades a renewed emphasis on laboratory spectroscopy has produced large sets of useful atomic transition probabilities for species of interest to stellar spectroscopists. In many cases the transition data are of such high quality that they play little part in the abundance error budgets. In this talk we will review the current state of atomic parameters, highlighting the areas of satisfactory progress and noting places where further laboratoryprogress will be welcome.

  4. NIST Databases on Atomic Spectra

    Science.gov (United States)

    Reader, J.; Wiese, W. L.; Martin, W. C.; Musgrove, A.; Fuhr, J. R.

    2002-11-01

    The NIST atomic and molecular spectroscopic databases now available on the World Wide Web through the NIST Physics Laboratory homepage include Atomic Spectra Database, Ground Levels and Ionization Energies for the Neutral Atoms, Spectrum of Platinum Lamp for Ultraviolet Spectrograph Calibration, Bibliographic Database on Atomic Transition Probabilities, Bibliographic Database on Atomic Spectral Line Broadening, and Electron-Impact Ionization Cross Section Database. The Atomic Spectra Database (ASD) [1] offers evaluated data on energy levels, wavelengths, and transition probabilities for atoms and atomic ions. Data are given for some 950 spectra and 70,000 energy levels. About 91,000 spectral lines are included, with transition probabilities for about half of these. Additional data resulting from our ongoing critical compilations will be included in successive new versions of ASD. We plan to include, for example, our recently published data for some 16,000 transitions covering most ions of the iron-group elements, as well as Cu, Kr, and Mo [2]. Our compilations benefit greatly from experimental and theoretical atomic-data research being carried out in the NIST Atomic Physics Division. A new compilation covering spectra of the rare gases in all stages of ionization, for example, revealed a need for improved data in the infrared. We have thus measured these needed data with our high-resolution Fourier transform spectrometer [3]. An upcoming new database will give wavelengths and intensities for the stronger lines of all neutral and singly-ionized atoms, along with energy levels and transition probabilities for the persistent lines [4]. A critical compilation of the transition probabilities of Ba I and Ba II [5] has been completed and several other compilations of atomic transition probabilities are nearing completion. These include data for all spectra of Na, Mg, Al, and Si [6]. Newly compiled data for selected ions of Ne, Mg, Si and S, will form the basis for a new

  5. Enhancing Light-Atom Interactions via Atomic Bunching

    CERN Document Server

    Schmittberger, Bonnie L

    2014-01-01

    There is a broad interest in enhancing the strength of light-atom interactions to the point where injecting a single photon induces a nonlinear material response. Here, we show theoretically that sub-Doppler-cooled, two-level atoms that are spatially organized by weak optical fields give rise to a nonlinear material response that is greatly enhanced beyond that attainable in a homogeneous gas. Specifically, in the regime where the intensity of the applied optical fields is much less than the off-resonant saturation intensity, we show that the third-order nonlinear susceptibility scales inversely with atomic temperature and, due to this scaling, can be two orders of magnitude larger than that of a homogeneous gas for typical experimental parameters. As a result, we predict that spatially bunched two-level atoms can exhibit single-photon nonlinearities. Our model is valid for all atomic temperature regimes and simultaneously accounts for the back-action of the atoms on the optical fields. Our results agree with...

  6. Sympathetic cooling of fluorine atoms with ultracold atomic hydrogen

    CERN Document Server

    González-Martínez, Maykel L

    2013-01-01

    We consider the prospect of using ultracold hydrogen atoms for sympathetic cooling of fluorine atoms to microkelvin temperatures. We carry out quantum-mechanical calculations on collisions between cold F and H atoms in magnetically trappable states and show that the ratio of elastic to inelastic cross sections remains high across a wide range of temperatures and magnetic fields. For F atoms initially in the spin-stretched state ($^2$P$_{3/2}$, $f=m_f=+2$), sympathetic cooling appears likely to succeed from starting temperatures around 1 K or even higher. This occurs because inelastic collisions are suppressed by p-wave and d-wave barriers that are 600 mK and 3.2 K high, respectively. In combination with recent results on H + NH and H + OH collisions [M. L. Gonz\\'alez-Mart\\'{\\i}nez and J. M. Hutson, arXiv:1305.6282 (2013)], this establishes ultracold H atoms as a very promising and versatile coolant for atoms and molecules that cannot be laser-cooled.

  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. Atomic level analysis of biomolecules by the scanning atom probe

    International Nuclear Information System (INIS)

    Utilizing the unique features of the scanning atom probe (SAP) the binding states of the biomolecules, leucine and methionine, are investigated at atomic level. The molecules are mass analyzed by detecting a single atom and/or clustering atoms field evaporated from a specimen surface. Since the field evaporation is a static process, the evaporated clustering atoms are closely related with the binding between atoms forming the molecules. For example, many thiophene radicals are detected when polythiophene is mass analyzed by the SAP. In the present study the specimens are prepared by immersing a micro cotton ball of single walled carbon nanotubes (SWCNT) in the leucine or methionine solution. The mass spectra obtained by analyzing the cotton balls exhibit singly and doubly ionized carbon ions of SWCNT and the characteristic fragments of the molecules, CH3, CHCH3, C4H7, CHNH2 and COOH for leucine and CH3, SCH3, C2H4, C4H7, CHNH2 and COOH for methionine.

  9. Newer insights in teledermatology practice

    Directory of Open Access Journals (Sweden)

    Garehatty Rudrappa Kanthraj

    2011-01-01

    Full Text Available The study and practice of dermatology care using interactive audio, visual, and data communications from a distance is called teledermatology. A teledermatology practice (TP provides teleconsultation as well tele-education. Initially, dermatologists used videoconference. Convenience, cost-effectiveness and easy application of the practice made "store and forward" to emerge as a basic teledermatology tool. The advent of newer technologies like third generation (3G and fourth generation (4G mobile teledermatology (MT and dermatologists′ interest to adopt tertiary TP to pool expert (second opinion to address difficult-to-manage cases (DMCs has resulted in a rapid change in TP. Online discussion groups (ODGs, author-based second opinion teledermatology (AST, or a combination of both are the types of tertiary TP. This article analyzes the feasibility studies and provides latest insight into TP with a revised classification to plan and allocate budget and apply appropriate technology. Using the acronym CAP-HAT, which represents five important factors like case, approach, purpose, health care professionals, and technology, one can frame a TP. Store-and-forward teledermatology (SAFT is used to address routine cases (spotters. Chronic cases need frequent follow-up care. Leg ulcer and localized vitiligo need MT while psoriasis and leprosy require SAFT. Pigmented skin lesions require MT for triage and combination of teledermoscopy, telepathology, and teledermatology for diagnosis. A self-practising dermatologist and national health care system dermatologist use SAFT for routine cases and a combination of ASTwith an ODG to address a DMC. A TP alone or in combination with face-to-face consultation delivers quality care.

  10. Electron elastic scattering off endohedral fullerenes A@C60: The initial insight

    CERN Document Server

    Dolmatov, V K; Hunter, H E

    2014-01-01

    The initial insight into electron elastic scattering off endohedral fullerenes A@C60 is gained in the framework of a theoretical approach where the C60 cage is modelled by a rectangular (in the radial coordinate) potential well, as in many other A@C60 studies. The effect of a noticeably weaker electron elastic scattering off A@C60 compared to that off empty C60 or even the isolated atom A itself, as well as a strong sensitivity of e + A@C60 scattering to the spin of the captured atom A are unraveled, for certain kinds of atoms. Obtained results lay out the initial qualitative basis for identifying interesting measurements and/or more rigorous calculations of e + A@C60 elastic scattering to perform.

  11. Atomic Scale Analysis of the Enhanced Electro- and Photo-Catalytic Activity in High-Index Faceted Porous NiO Nanowires

    Science.gov (United States)

    Shen, Meng; Han, Ali; Wang, Xijun; Ro, Yun Goo; Kargar, Alireza; Lin, Yue; Guo, Hua; Du, Pingwu; Jiang, Jun; Zhang, Jingyu; Dayeh, Shadi A.; Xiang, Bin

    2015-02-01

    Catalysts play a significant role in clean renewable hydrogen fuel generation through water splitting reaction as the surface of most semiconductors proper for water splitting has poor performance for hydrogen gas evolution. The catalytic performance strongly depends on the atomic arrangement at the surface, which necessitates the correlation of the surface structure to the catalytic activity in well-controlled catalyst surfaces. Herein, we report a novel catalytic performance of simple-synthesized porous NiO nanowires (NWs) as catalyst/co-catalyst for the hydrogen evolution reaction (HER). The correlation of catalytic activity and atomic/surface structure is investigated by detailed high resolution transmission electron microscopy (HRTEM) exhibiting a strong dependence of NiO NW photo- and electrocatalytic HER performance on the density of exposed high-index-facet (HIF) atoms, which corroborates with theoretical calculations. Significantly, the optimized porous NiO NWs offer long-term electrocatalytic stability of over one day and 45 times higher photocatalytic hydrogen production compared to commercial NiO nanoparticles. Our results open new perspectives in the search for the development of structurally stable and chemically active semiconductor-based catalysts for cost-effective and efficient hydrogen fuel production at large scale.

  12. Absorption properties of identical atoms

    Energy Technology Data Exchange (ETDEWEB)

    Sancho, Pedro, E-mail: psanchos@aemet.es

    2013-09-15

    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.

  13. Relativistic calculations of atomic structure

    OpenAIRE

    Fricke, Burkhard

    1984-01-01

    A review of relativistic atomic structure calculations is given with a emphasis on the Multiconfigurational-Dirac-Fock method. Its problems and deficiencies are discussed together with the contributions which go beyond the Dirac-Fock procedure.

  14. Realization of Semantic Atom Blog

    CERN Document Server

    Patel, Dhiren R

    2009-01-01

    Web blog is used as a collaborative platform to publish and share information. The information accumulated in the blog intrinsically contains the knowledge. The knowledge shared by the community of people has intangible value proposition. The blog is viewed as a multimedia information resource available on the Internet. In a blog, information in the form of text, image, audio and video builds up exponentially. The multimedia information contained in an Atom blog does not have the capability, which is required by the software processes so that Atom blog content can be accessed, processed and reused over the Internet. This shortcoming is addressed by exploring OWL knowledge modeling, semantic annotation and semantic categorization techniques in an Atom blog sphere. By adopting these techniques, futuristic Atom blogs can be created and deployed over the Internet.

  15. $T^3$-interferometer for atoms

    CERN Document Server

    Zimmermann, M; Roura, A; Schleich, W P; DeSavage, S A; Davis, J P; Srinivasan, A; Narducci, F A; Werner, S A; Rasel, E M

    2016-01-01

    The quantum mechanical propagator of a massive particle in a linear gravitational potential derived already in 1927 by Earle H. Kennard \\cite{Kennard,Kennard2} contains a phase that scales with the third power of the time $T$ during which the particle experiences the corresponding force. Since in conventional atom interferometers the internal atomic states are all exposed to the same acceleration $a$, this $T^3$-phase cancels out and the interferometer phase scales as $T^2$. In contrast, by applying an external magnetic field we prepare two different accelerations $a_1$ and $a_2$ for two internal states of the atom, which translate themselves into two different cubic phases and the resulting interferometer phase scales as $T^3$. We present the theoretical background for, and summarize our progress towards experimentally realizing such a novel atom interferometer.

  16. Dimer-atom-atom recombination in the universal four-boson system

    OpenAIRE

    Deltuva, A.

    2012-01-01

    The dimer-atom-atom recombination process in the system of four identical bosons with resonant interactions is studied. The description uses the exact Alt, Grassberger and Sandhas equations for the four-particle transition operators that are solved in the momentum-space framework. The dimer-dimer and atom-trimer channel contributions to the ultracold dimer-atom-atom recombination rate are calculated. The dimer-atom-atom recombination rate greatly exceeds the three-atom recombination rate.

  17. 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....

  18. A polarized atomic hydrogen beam

    OpenAIRE

    Chan, N; Crowe, D.M.; Lubell, M. S.; Tang, F.C.; Vasilakis, A.; Mulligan, F. J.; Slevin, J.

    1988-01-01

    We describe the design and operating characteristics of a simple polarized atomic hydrogen beam particularly suitable for applications to crossed beams experiments. In addition to experimental measurements, we present the results of detailed computer models, using Monte-Carlo ray tracing techniques, optical analogs, and phase-space methods, that not only provide us with a confirmation of our measurement, but also allow us to characterize the density, polarization, and atomic fraction of the b...

  19. Generalized Liquid Film Atomization Theory

    Institute of Scientific and Technical Information of China (English)

    HeraldoS.Couto; DemetrioBastos-Netto

    2000-01-01

    The increase of the fuel burning area required by most practical combustion processes in order to guarantee the minimum energy density rate release for their start up and operation is normally achieved by the proper choice among several existing types of atomizers.For instance.impinging and multi-impinging jets atomizers are used in rocket combustion chambers.while splash-plate atomizers find their use when wall film cooling is required.Pressure swirl atomizers,either of simplex or duplex kind,along with Y-jet or SPider Jet atomizers are used in industrial applications and in turbine combustion chambers.Notice.however,that all the types of atomizing devices listed above have one point in common:they are of pre-filming kind.i.e.,befor the droplet spray is generated,a liquid film is formed.This liquid film is broken into unstable ligaments which contract under the action of surface tension forming the droplets.Once the film thickness is estimated.the droplets'SMD(Sauter Mean Diameter)can be calculated.yielding a crucial prameter for the combustion chamber design.However,although this mechanism of droplet fromation has been under study for several decades.most of the available results.are based upon experimental data.valid for a special type of atomizer under the given sepcific conditions only.This work offers a generalized theory for theoretically estimating the SMD of sprays generated by liquid pre-filming atomizers in gereral.

  20. Advanced atomic force microscopy techniques

    OpenAIRE

    Thilo Glatzel; Hendrik Hölscher; Thomas Schimmel; Baykara, Mehmet Z; Schwarz, Udo D.; Ricardo Garcia

    2012-01-01

    Although its conceptual approach is as simple as the technique used in record players already introduced in the 19th century, the invention of the atomic force microscope (AFM) in 1986 by Binnig, Quate, and Gerber was a milestone for nanotechnology. The scanning tunneling microscope (STM), introduced some years earlier, had already achieved atomic resolution, but is limited to conductive surfaces. Since its operational principle is based on the detection of the forces acting between tip and s...