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Sample records for ag111 surfaces synchrotron

  1. Structure and growth of dotriacontane films on SiO_2 and Ag(111) surfaces: synchrotron X-ray scattering and molecular dynamics simulations

    DEFF Research Database (Denmark)

    Mo, H.; Trogisch, S.; Taub, H.;

    2004-01-01

    We report synchrotron X-ray scattering experiments and molecular dynamics simulations of the structure and growth mode of dotriacontane (n-C32H(66) or C32) films adsorbed on Ag(111) and SiO2-coated Si(100) substrates. On the SiO2 surface, the X-ray measurements confirm a structural model of the...

  2. First-principles study of surface plasmons on Ag(111) and H/Ag(111)

    DEFF Research Database (Denmark)

    Yan, Jun; Jacobsen, Karsten Wedel; Thygesen, Kristian Sommer

    2011-01-01

    Linear-response time-dependent density functional theory is used to investigate the relation between molecular bonding and surface plasmons for the model system H/Ag(111). We employ an orbital-dependent exchange-correlation functional to obtain a correct description of the Ag 3d band, which is...

  3. Point defects in epitaxial silicene on Ag(111) surfaces

    Science.gov (United States)

    Liu, Hongsheng; Feng, Haifeng; Du, Yi; Chen, Jian; Wu, Kehui; Zhao, Jijun

    2016-06-01

    Silicene, a counterpart of graphene, has achieved rapid development due to its exotic electronic properties and excellent compatibility with the mature silicon-based semiconductor technology. Its low room-temperature mobility of ∼100 cm2 V‑1 s‑1, however, inhibits device applications such as in field-effect transistors. Generally, defects and grain boundaries would act as scattering centers and thus reduce the carrier mobility. In this paper, the morphologies of various point defects in epitaxial silicene on Ag(111) surfaces have been systematically investigated using first-principles calculations combined with experimental scanning tunneling microscope (STM) observations. The STM signatures for various defects in epitaxial silicene on Ag(111) surface are identified. In particular, the formation energies of point defects in Ag(111)-supported silicene sheets show an interesting dependence on the superstructures, which, in turn, may have implications for controlling the defect density during the synthesis of silicene. Through estimating the concentrations of various point defects in different silicene superstructures, the mystery of the defective appearance of \\sqrt{13}× \\sqrt{13} and 2\\sqrt{3}× 2\\sqrt{3} silicene in experiments is revealed, and 4 × 4 silicene sheet is thought to be the most suitable structure for future device applications.

  4. Hindered rotational physisorption states of H2 on Ag(111) surfaces.

    Science.gov (United States)

    Kunisada, Y; Kasai, H

    2015-07-15

    We have investigated the physisorption states of H2 on Ag(111) surfaces. To clarify the accurate adsorption properties of H2 on Ag(111), we performed first-principles calculations based on spin-polarized density functional theory (DFT) with the semiempirical DFT-D2 method and the newly-developed exchange functional with the non-local correlation functional vdW-DF2 (rev-vdW-DF2). We constructed exhaustive potential energy surfaces, and revealed that non-negligible out-of-plane potential anisotropy with a perpendicular orientation preference exists even for H2 physisorption on planar Ag(111), as predicted by previous results of resonance-enhanced multiphoton ionization spectroscopy and temperature-programmed desorption experiments. Therefore, the molecular rotational ground states of ortho-H2 split into two energy levels in the anisotropic potential. The obtained adsorption energy and the number of bound states, including the zero-point energies and the rotational energy shift, agree with diffractive and rotationally mediated selective adsorption scattering resonance measurements. The origin of the potential anisotropy on Ag(111) is a combination of the London dispersion interaction and the virtual transition of the metal electron to the unoccupied molecular state. PMID:26151425

  5. Long-range surface faceting induced by chemisorption of PTCDA on stepped Ag(111) surfaces

    Science.gov (United States)

    Schmitt, Stefan; Schöll, Achim; Umbach, Eberhard

    2016-01-01

    The organic molecule PTCDA preferentially adsorbs on steps of vicinal Ag(111) surfaces and bunches them to well defined facet planes. These depend on coverage and annealing temperature and are independent of the nominal step direction and angle of inclination of the unreconstructed initial surface. We study the development of the facets and present a map of all 16 types of facets in a stereographic triangle of 35° off the [111]-direction. The faceting mechanism is interpreted as orientational phase separation originating from different bonding strengths of PTCDA on various facets. The faceting drives the system to the minimum of its surface free energy.

  6. Enhanced Rashba spin-orbit splitting in Bi/Ag(111) and Pb/Ag(111) surface alloys from first principles

    OpenAIRE

    Bihlmayer, G; Blügel, S.; Chulkov, E. V.

    2007-01-01

    We present first-principles calculations of a (root 3x root 3) R30 degrees Bi/Ag (111)-ordered surface alloy, which has recently been investigated experimentally using angle-resolved photoemission spectroscopy. The surface states in the L-projected bulk band gap show a Rashba-type spin-orbit splitting which is three times larger than what has been observed on a clean Bi (111) surface. This large enhancement can be explained by the strong distortion of the surface-state wave function which is ...

  7. Self-assembled rows of Ni porphyrin dimers on the Ag(111) surface

    OpenAIRE

    SENGE, Mathias; SERGEEVA, NATALIA

    2010-01-01

    PUBLISHED The growth and ordering of 5-(10,15,20-triphenylporphyrinatonickel(II))dimer (NiTPP-dimer) molecules on the Ag(111) surface have been investigated using scanning tunnelling microscopy/spectroscopy (STM/STS) and low-energy electron diffraction (LEED). At one monolayer (ML) coverage the NiTPP-dimer forms a well-ordered close-packed molecular layer in which the porphyrin molecules have a flat orientation with the molecular plane lying parallel to the substrate. STM and LEED data obt...

  8. Benzene derivatives adsorbed to the Ag(111) surface: Binding sites and electronic structure

    Energy Technology Data Exchange (ETDEWEB)

    Miller, Daniel P.; Tymińska, Nina; Zurek, Eva, E-mail: ezurek@buffalo.edu [Department of Chemistry, State University of New York at Buffalo, Buffalo, New York 14260-3000 (United States); Simpson, Scott [Department of Chemistry, State University of New York at Buffalo, Buffalo, New York 14260-3000 (United States); School of Science, Penn State Erie, The Behrend College, 4205 College Drive, Erie, Pennsylvania 16563 (United States)

    2015-03-14

    Dispersion corrected Density Functional Theory calculations were employed to study the adsorption of benzenes derivatized with functional groups encompassing a large region of the activated/deactivated spectrum to the Ag(111) surface. Benzenes substituted with weak activating or deactivating groups, such as methyl and fluoro, do not have a strong preference for adsorbing to a particular site on the substrate, with the corrugations in the potential energy surface being similar to those of benzene. Strong activating (N(CH{sub 3}){sub 2}) and deactivating (NO{sub 2}) groups, on the other hand, possess a distinct site preference. The nitrogen in the former prefers to lie above a silver atom (top site), but in the latter a hollow hexagonal-closed-packed (H{sub hcp}) site of the Ag(111) surface is favored instead. Benzenes derivatized with classic activating groups donate electron density from their highest occupied molecular orbital to the surface, and those functionalized with deactivating groups withdraw electron density from the surface into orbitals that are unoccupied in the gas phase. For benzenes functionalized with two substituents, the groups that are strongly activating or deactivating control the site preference and the other groups assume sites that are, to a large degree, dictated by their positions on the benzene ring. The relative stabilities of the ortho, meta, and para positional isomers of disubstituted benzenes can, in some cases, be modified by adsorption to the surface.

  9. Benzene derivatives adsorbed to the Ag(111) surface: Binding sites and electronic structure

    International Nuclear Information System (INIS)

    Dispersion corrected Density Functional Theory calculations were employed to study the adsorption of benzenes derivatized with functional groups encompassing a large region of the activated/deactivated spectrum to the Ag(111) surface. Benzenes substituted with weak activating or deactivating groups, such as methyl and fluoro, do not have a strong preference for adsorbing to a particular site on the substrate, with the corrugations in the potential energy surface being similar to those of benzene. Strong activating (N(CH3)2) and deactivating (NO2) groups, on the other hand, possess a distinct site preference. The nitrogen in the former prefers to lie above a silver atom (top site), but in the latter a hollow hexagonal-closed-packed (Hhcp) site of the Ag(111) surface is favored instead. Benzenes derivatized with classic activating groups donate electron density from their highest occupied molecular orbital to the surface, and those functionalized with deactivating groups withdraw electron density from the surface into orbitals that are unoccupied in the gas phase. For benzenes functionalized with two substituents, the groups that are strongly activating or deactivating control the site preference and the other groups assume sites that are, to a large degree, dictated by their positions on the benzene ring. The relative stabilities of the ortho, meta, and para positional isomers of disubstituted benzenes can, in some cases, be modified by adsorption to the surface

  10. Diffusion of Cu adatoms and dimers on Cu(111) and Ag(111) surfaces

    Science.gov (United States)

    Mińkowski, Marcin; Załuska-Kotur, Magdalena A.

    2015-12-01

    Diffusion of Cu adatoms and dimers on Cu(111) and Ag(111) surfaces is analyzed based on ab initio surface potentials. Single adatom diffusion is compared with dimer diffusion on both surfaces. Surface geometry makes the adatoms jump alternately between two states in the same way in both systems, whereas dimers undergo more complex diffusion process that combines translational and rotational motion. Small difference in the surface lattice constant between Cu and Ag crystals results in a completely different energy landscape for dimer jumps. As an effect the character of diffusion process changes. Homogeneous Cu dimer diffusion is more difficult and dimers rather rotate within single surface cell, whereas diffusion over Ag surface is faster and happens more smoothly. The temperature dependence of diffusion coefficient and its parameters: energy barrier and prefactor is calculated and compared for both surfaces.

  11. Formation of surface oxides and Ag2O thin films with atomic oxygen on Ag(111)

    Science.gov (United States)

    Derouin, Jonathan; Farber, Rachael G.; Heslop, Stacy L.; Killelea, Daniel R.

    2015-11-01

    The nature of the oxygen species adsorbed to silver surfaces is a key component of the heterogeneously catalyzed epoxidation of ethylene and partial oxidation of methanol over silver catalysts. We report the formation of two different silver-oxygen species depending on the flux and energy of incident gas-phase oxygen atoms on an Ag(111) surface. A combination of surface science techniques was used to characterize the oxidized surfaces. Atomic oxygen was generated with an Ir filament; lower temperatures created surface oxides previously reported. When O was deposited with a higher filament temperature, the surface became highly corrugated, little subsurface oxygen was observed, and thin layers of Ag2O were likely formed. These results show that the energy and flux of oxygen are important parameters in the chemical identity and abundance of oxygen on silver surfaces and suggest that formation of the Ag2O thin film hinders formation of subsurface oxygen.

  12. Lateral interaction and structures in Cl adlayers on the Ag(111) surface

    International Nuclear Information System (INIS)

    Graphical abstract: The sharpness of the order-disorder transition for the (√3 x √3)R30o structure depends on the rate of cooling, as is illustrated by two plots obtained with Monte Carlo simulation for the 2 K (solid line) and 5 K (dash line) temperature steps. Display Omitted Highlights: →Energies of lateral interaction for Cl on Ag(111) are determined from DFT. → Structures and order-disorder transitions are studied via Monte Carlo simulations. → The disordering of the (√3 x √3)R30o structure is abrupt. → Antiphase domains of the honeycomb structure cancel the (2 x 2) LEED pattern. - Abstract: The lateral interaction and formation of ordered structures in Cl submonolayers adsorbed on Ag(111) surface at low coverages (up to 0.5 ML), when the diffusion of Cl into the bulk is negligible, have been studied by Monte Carlo method using parameters of the lateral interaction estimated from DFT calculations. The transition temperature and sharpness of the order-disorder transition for the (√3 x √3)R30o structure, derived from the Monte Carlo simulation, are in good agreement with available experimental data. It has been demonstrated that a restricted mobility of adsorbed Cl atoms can result, for a relatively high rate of the cooling of the layer, in the formation of domain structures. For imperfect domain structures, the model LEED patterns show a characteristic splitting of reflections due to phase shifts for electrons scattered at different domains.

  13. Relaxation of surface stress induced by an organic adsorbate: PTCDA on vicinal Ag(111)

    Energy Technology Data Exchange (ETDEWEB)

    Pollinger, Florian; Vrdoljak, Pavo; Fertig, Dominik; Schmitt, Stefan; Kumpf, Christian; Schoell, Achim; Umbach, Eberhard [Universitaet Wuerzburg, Experimentelle Physik II, Am Hubland, 97074 Wuerzburg (Germany); Tian, Zhen; Sander, Dirk; Kirschner, Juergen [Max-Planck-Institut fuer Mikrostrukturphysik, Weinberg 2, 06120 Halle (Germany)

    2007-07-01

    Self-organization of metallic surfaces on large scales can be induced by the adsorption of organic molecules and has been observed in several experiments. One example is the growth of 3,4,9,10-perylenetetracarboxylic-acid dianhydride (PTCDA) on stepped (8.5 -vicinal) Ag(111) surfaces. At elevated temperatures, the adsorbate molecules lead to a bunching of substrate steps, which agglomerate to facets of critical sizes. The facets arrange in a coverage-dependent grating-like pattern on a mesoscopic length scale. The resulting order requires a long-range interaction which is mediated by the substrate. It can be explained by a change of surface stress induced by the adsorbate layer. Experimentally, such a change is directly accessible by an optical cantilever bending technique. We monitored the bending of a faceting thin Ag(10 8 7) crystal with this method in order to quantify the occurring relaxation of surface stress.

  14. Nature of free-electron-like states in PTCDA molecules adsorbed on an Ag(111) surface

    Energy Technology Data Exchange (ETDEWEB)

    Persson, Mats; Dyer, Matthew [Surface Science Research Centre, University of Liverpool, L69 3BX Liverpool (United Kingdom)

    2009-07-01

    Advances in molecular assembly experiments on metal surfaces and potential applications arising from them call for a better understanding of the electronic structure at the interface of metals and organic systems. There is a high interest in delocalized electronic states, because of their potential use in molecular and opto-electronics applications. Recently, unoccupied, free-electron-like states arising in mono layers of 3,4,9,10-perylene-tetracarboxylic acid dianhydride (PTCDA) molecules adsorbed on an Ag(111) surface at energies close to the Fermi energy have been observed by scanning tunneling and photoemission spectroscopies. So as to reveal the nature of these delocalized states we have carried out a density functional study of the electronic structure and local density of states of these systems. We show that the observed free-electron state originates from a Shockley surface state (SS) at the zone centre of the bare surface. The SS is shifted up by the interaction with the organic overlayer.

  15. Change in surface states of Ag(111) thin films upon adsorption of a monolayer of PTCDA organic molecules

    International Nuclear Information System (INIS)

    The change in the electronic structure of silver thin films of different thicknesses with the Ag( 111) orientation due to the interaction with an adsorbed monolayer of ordered organic molecules of 3,4,9,10-perylene-tetracarboxylic acid dianhydride (PTCDA) has been investigated in terms of density functional theory. It has been shown that one of the two surface states of the pure films transforms into an unocc upied interface state due to the interaction so that all the main features of the initial state are retained. The relation of the resulting state to the unoccupied state experimentally observed in the PTCDA/Ag( 111 ) system by scanning tunneling and two-photon photoemission spectroscopy has been discussed.

  16. C60 chain phases on ZnPc/Ag(111) surfaces: Supramolecular organization driven by competing interactions.

    Science.gov (United States)

    Jin, W; Liu, Q; Dougherty, D B; Cullen, W G; Reutt-Robey, J E; Weeks, J; Robey, S W

    2015-03-14

    Serpentine chain C60 phases were observed in scanning tunneling microscopy (STM) images of C60 layers on zinc phthalocyanine (ZnPc) or pentacene covered Ag(111) and Au(111) surfaces. This low-density, quasi-one-dimensional organization contrasts starkly with the close-packed hexagonal phases observed for C60 layers on bare metal substrates. STM was employed to perform a detailed investigation of these chain structures for C60/ZnPc/Ag(111) heterolayers. Motivated by the similarity of these chain phases, and the chain and stripe organization occurring in dipole-fluid systems, we investigated a model based on competing van der Waals attractions and electrostatic repulsions between C60 molecules as an explanation for the driving force behind these monolayer phases. Density functional theory (DFT) calculations revealed significant charge transfer to C60 from the Ag(111) substrate, through the intervening ZnPc layer, inducing electrostatic interactions between C60 molecules. Molecular dynamics simulations performed with attractive van der Waals interactions plus repulsive dipole-dipole interactions reproduced the C60 chain phases with dipole magnitudes consistent with DFT calculations. PMID:25770499

  17. Manipulation of the surface density of states of Ag(111) by means of resonators: Experiment and theory

    Science.gov (United States)

    Fernández, J.; Moro-Lagares, María; Serrate, D.; Aligia, A. A.

    2016-08-01

    We show that the density of surface Shockley states of Ag(111) probed by the differential conductance G (V )=d I /d V by a scanning-tunneling microscope (STM) can be enhanced significantly at certain energies and positions introducing simple arrays of Co or Ag atoms on the surface, in contrast to other noble-metal surfaces. Specifically we have studied resonators consisting of two parallel walls of five atoms deposited on the clean Ag(111) surface. A simple model in which the effect of the adatoms is taken into account by an attractive local potential and a small hybridization between surface and bulk at the position of the adatoms explains the main features of the observed G (V ) and allows us to extract the proportion of surface and bulk states sensed by the STM tip. These results might be relevant to engineer the surface spectral density of states, to study the effects of surface states on the Kondo effect, and to separate bulk and surface contributions in STM studies of topological surface states.

  18. Surface stress and its consequences: In-situ study of PTCDA induced faceting of vicinal Ag(111)

    Energy Technology Data Exchange (ETDEWEB)

    Pollinger, Florian; Vrdoljak, Pavo; Schmitt, Stefan; Kumpf, Christian; Schoell, Achim [Universitaet Wuerzburg, Experimentelle Physik II, Wuerzburg (Germany); Tian, Zhen; Sander, Dirk; Kirschner, Juergen [Max-Planck-Institut fuer Mikrostrukturphysik, Halle (Germany); Umbach, Eberhard [Universitaet Wuerzburg, Experimentelle Physik II, Wuerzburg (Germany); Forschungszentrum Karlsruhe (Germany)

    2008-07-01

    Adsorption of organic molecules on vicinal metal surfaces is known to promote faceting and self-organized ordering on mesoscopic scales. The adsorption of PTCDA on vicinal Ag(111) surfaces leads to grating-like structures after annealing. The system PTCDA/Ag(10 8 7) was investigated using two complementary techniques: An optical cantilever bending technique sensitive to changes in surface stress and spot-profile analysis low energy electron diffraction (SPA-LEED) to monitor the development of the interface structure during faceting. The data was compared to the related, non-faceting system PTCDA on Ag(111). Overall, we find a surface stress change of 0.7 N/m due to the PTCDA-induced faceting, whereas the adsorption of PTCDA without faceting induces a change of 0.4 N/m. Moreover, the data allows an explicit and unambiguous correlation of the surface stress change to the structural and morphological evolution of the interface during the adsorption of the PTCDA adlayer. In conclusion, the results provide experimental evidence for significant surface stress induced by an organic adsorbate and for its importance for faceting and long-range ordering at metal-organic interfaces.

  19. Adsorbate-induced facetting reconstruction and self-organized domain patterning of vicinal Ag(111) surfaces; Adsorbatinduzierte richtungsabhaengige Facettierung und selbstorganisierte Domaenen-Musterbildung auf vizinalen Ag(111)-Oberflaechen

    Energy Technology Data Exchange (ETDEWEB)

    Schmitt, Stefan

    2007-02-05

    This thesis investigates structural aspects of adsorbate-induced facetting of vicinal Ag(111) surfaces. It is mainly based on scanning tunneling microscope (STM) and low energy electron diffraction (LEED) experiments performed under UHV conditions. The planar dye-molecule perylene-3,4,9,10-tetracarboxilicacid-dianhydride (PTCDA) adsorbs preferentially at the step edges of the 8.5 Ag(111) vicinal surfaces used in the experiments. It causes a facetting reconstruction by the formation of (111) terraces and facets with a high step density. Moreover, two distinct preferential inclinations of facets were observed, which can only be explained by the selective influence of the adsorbate superstructure. In terms of thermodynamics, the facetting reconstruction can be described as an orientational phase separation, adapted to the constraints of planar surfaces. This concept is capable of explaining the local facetting phenomena. The formalism used predicts an important role of nucleation kinetics. This aspect is taken into account by introducing an additional phase of mobile molecules (2D molecular gas), which cannot be measured directly. Furthermore, strong arguments for the appearance of a critical island size for the PTCDA/ Ag(111) superstructure were found. This work presents structural information of all stable superstructures of PTCDA on vicinal Ag(111) surfaces. Altogether 16 such superstructures were found, 3 of which had been observed and published before. Density and commensurability were found to systematically depend on the step-structure. The two preferred inclinations of facets are related to two characteristic types of domain boundaries of the herringbone superstructure to the adjacent (111)-terrace. On the (111) terraces, small islands of metastable superstructures were found. Facets and (111) terraces form a regular grating-like domain pattern with a variable structural width of 5 to 75 nm. STM measurements show direct evidence for a long-range interaction

  20. Luminescence from 3,4,9,10-perylenetetracarboxylic dianhydride on Ag(111) surface excited by tunneling electrons in scanning tunneling microscopy.

    Science.gov (United States)

    Ino, Daisuke; Yamada, Taro; Kawai, Maki

    2008-07-01

    The electronic excitations induced with tunneling electrons into adlayers of 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) on Ag(111) have been investigated by in situ fluorescence spectroscopy in scanning tunneling microscopy (STM). A minute area of the surface is excited by an electron tunneling process in STM. Fluorescence spectra strongly depend on the coverage of PTCDA on Ag(111). The adsorption of the first PTCDA layer quenches the intrinsic surface plasmon originated from the clean Ag(111). When the second layer is formed, fluorescence spectra are dominated by the signals from PTCDA, which are interpreted as the radiative decay from the manifold of first singlet excited state (S(1)) of adsorbed PTCDA. The fluorescence of PTCDA is independent of the bias polarity. In addition, the fluorescence excitation spectrum agrees with that by optical excitation. Both results indicate that S(1) is directly excited by the inelastic impact scattering of electrons tunneling within the PTCDA adlayer. PMID:18624490

  1. Self-learning kinetic Monte Carlo simulations of self-diffusion of small Ag islands on the Ag(111) surface

    Science.gov (United States)

    Islamuddin Shah, Syed; Nandipati, Giridhar; Karim, Altaf; Rahman, Talat S.

    2016-01-01

    We studied self-diffusion of small two-dimensional Ag islands, containing up to ten atoms, on the Ag(111) surface using self-learning kinetic Monte Carlo (SLKMC) simulations. Activation barriers are calculated using the semi-empirical embedded atom method (EAM) potential. We find that two- to seven-atom islands primarily diffuse via concerted translation processes with small contributions from multi-atom and single-atom processes, while eight- to ten-atom islands diffuse via single-atom processes, especially edge diffusion, corner rounding and kink detachment, along with a minimal contribution from concerted processes. For each island size, we give a detailed description of the important processes, and their activation barriers, responsible for its diffusion.

  2. Direct Visualization of Surface Phase of Oxygen Molecules Physisorbed on the Ag(111) Surface: A Two-dimensional Quantum Spin System

    Science.gov (United States)

    Yamamoto, Shunji; Yoshida, Yasuo; Imada, Hiroshi; Kim, Yousoo; Hasegawa, Yukio

    Oxygen molecule (O2) is one of the smallest molecular magnets with an S = 1 quantum spin. This makes O2 attractive as a building block of low-dimensional (LD) quantum spin systems. Recently, the existence of a spin in physisorbed O2 on Ag(111) was confirmed by the ortho-para conversion of molecular hydrogen. Therefore, there is a strong need for STM-based techniques with single-molecule resolution in order to verify the potential of the O2/Ag(111) for LD quantum spin systems. Here we report the real-space observation of oxygen molecules physisorbed on an Ag(111) surface by using low-temperature scanning tunneling microscopy and spectroscopy. A well-ordered O2 structure was observed, and the lattice was distorted from an isosceles triangular lattice. The distortion can be explained by the competition between the magnetic and elastic instabilities of the O2 lattice. In differential tunneling conductance spectra, we found no feature of the Kondo resonance at 4.7 K; in contrast, the physisorbed O2 on Ag(110) showed a clear Kondo resonance at 18 K. Based on these observations, we discuss the realization of an S = 1 two-dimensional antiferromagnetic quantum spin system.

  3. Slow positrons in metal single crystals. I. Positronium formation at Ag(100), Ag(111), and Cu(111) surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Lynn, K.G.; Welch, D.O.

    1980-07-01

    Monoenergetic positrons, with an incident energy of 0 --5 keV, were focused onto Ag(100), Ag(111), and Cu(111) surfaces with submonolayer contamination, and positronium formation was studied as a function of sample temperature from 300 to 1200 K. The data were fitted with a simple positron diffusion model including surface and vacancy trapping, assuming that positronium is formed only at the surface. The formation of part of the positronium fraction is found to be a temperature-activated process which is identified as detrapping from a surface state, and an estimate of the binding energy in this trap is deduced. The diffusion length is found to be only slightly temperature dependent between room temperature and the onset of vacancy trapping. At the higher sample temperatures positron trapping at thermally generated vacancies is observed by the decrease in the positron diffusion length at the higher incident voltages. A vacancy formation energy is extracted from the data and is generally found to be lower than the values obtained from bulk measurements.

  4. Theoretical study of PTCDA adsorbed on the coinage metal surfaces, Ag(111), Au(111) and Cu(111)

    Energy Technology Data Exchange (ETDEWEB)

    Romaner, L; Nabok, D; Puschnig, P; Ambrosch-Draxl, C [Chair of Atomistic Modelling and Design of Materials, University of Leoben, Franz-Josef-Strasse 18, A-8700 Leoben (Austria); Zojer, E [Institute of Solid State Physics, Graz University of Technology, Petersgasse 16, A-8010 Graz (Austria)], E-mail: lorenz.romaner@unileoben.ac.at

    2009-05-15

    A thorough understanding of the adsorption of molecules on metallic surfaces is a crucial prerequisite for the development and improvement of functionalized materials. A prominent representative within the class of {pi}-conjugated molecules is 3,4,9,10-perylene-tetracarboxylic acid dianhydride (PTCDA) which, adsorbed on the Ag(111), Au(111) or Cu(111) surfaces, shows characteristic trends for work-function modification, alignment of molecular levels with the substrate Fermi energy and binding distances. We carried out density functional theory (DFT) calculations to investigate to what extent these trends can be rationalized on a theoretical basis. We used different density functionals (DF) including a fully non-local van der Waals (vdW) DF capable of describing dispersion interactions. We show that, rather independent of the DF, the calculations yield level alignments and work-function modifications consistent with ultra-violet photoelectron spectroscopy when the monolayer is placed onto the surfaces at the experimental distances (as determined from x-ray standing wave experiments). The lowest unoccupied molecular orbital is occupied on the Ag and Cu surfaces, whereas it remains unoccupied on the Au surface. Simultaneously, the work function increases for Ag but decreases for Cu and Au. Adsorption distances and energies, on the other hand, depend very sensitively on the choice of the DF. While calculations in the local density approximation bind the monolayer consistently with the experimental trends, the generalized gradient approximation in several flavors fails to reproduce realistic distances and energies. Calculations employing the vdW-DF reveal that substantial bonding contributions arise from dispersive interactions. They yield reasonable binding energies but larger binding distances than the experiments.

  5. Theoretical study of PTCDA adsorbed on the coinage metal surfaces, Ag(111), Au(111) and Cu(111)

    International Nuclear Information System (INIS)

    A thorough understanding of the adsorption of molecules on metallic surfaces is a crucial prerequisite for the development and improvement of functionalized materials. A prominent representative within the class of π-conjugated molecules is 3,4,9,10-perylene-tetracarboxylic acid dianhydride (PTCDA) which, adsorbed on the Ag(111), Au(111) or Cu(111) surfaces, shows characteristic trends for work-function modification, alignment of molecular levels with the substrate Fermi energy and binding distances. We carried out density functional theory (DFT) calculations to investigate to what extent these trends can be rationalized on a theoretical basis. We used different density functionals (DF) including a fully non-local van der Waals (vdW) DF capable of describing dispersion interactions. We show that, rather independent of the DF, the calculations yield level alignments and work-function modifications consistent with ultra-violet photoelectron spectroscopy when the monolayer is placed onto the surfaces at the experimental distances (as determined from x-ray standing wave experiments). The lowest unoccupied molecular orbital is occupied on the Ag and Cu surfaces, whereas it remains unoccupied on the Au surface. Simultaneously, the work function increases for Ag but decreases for Cu and Au. Adsorption distances and energies, on the other hand, depend very sensitively on the choice of the DF. While calculations in the local density approximation bind the monolayer consistently with the experimental trends, the generalized gradient approximation in several flavors fails to reproduce realistic distances and energies. Calculations employing the vdW-DF reveal that substantial bonding contributions arise from dispersive interactions. They yield reasonable binding energies but larger binding distances than the experiments.

  6. PTCDA induced faceting of a vicinal Ag(111) surface: an in-situ LEEM study

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, Thomas; Marchetto, Helder; Sala, Alessandro; Freund, Hajo [Fritz-Haber-Institut, Abt. CP, 14195 Berlin (Germany); Pollinger, Florian; Schmitt, Stefan; Maier, Florian C.; Reinert, Friedrich T. [Universitaet Wuerzburg, EP II, 97074 Wuerzburg (Germany); Umbach, Eberhard [Universitaet Wuerzburg, EP II, 97074 Wuerzburg (Germany); Forschungszentrum Karlsruhe, 76021 Karlsruhe (Germany)

    2009-07-01

    Adsorption of organic molecules on vicinal metal surfaces is known to promote faceting and self-organized ordering on mesoscopic scales. In the temperature range between 400 K and 620 K the adsorption of PTCDA on a Ag(10 8 7) surface has been studied in-situ and in real-time by LEEM (low energy electron microscopy) and LEED, using the SMART microscope. The deposition of one organic layer leads to grating-like structures. The direct observation reveals a two-step process: first, facets with an angle of ca. 25 inclination are formed with (111) orientated areas in between, whereas only the facets are covered by PTCDA. In a second step the bare (111) areas are covered by PTCDA, forming a complete monolayer. The temperature dependence of the structure sizes and the influence of inhomogeneity in the initial substrate step density are discussed.

  7. The molecular dynamic study of anharmonic effects at Cu(111) and Ag(111) surfaces in the presence of Cu- and Ag-trimer island

    Energy Technology Data Exchange (ETDEWEB)

    Shah, Zulfiqar Ali [Department of Physics, Hazara University, Mansehra 21300 (Pakistan); Hayat, Sardar Sikandar, E-mail: sikandariub@yahoo.com [Department of Physics, Hazara University, Mansehra 21300 (Pakistan); Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63120 (Pakistan); Rehman, Z. [Department of Physics, Hazara University, Mansehra 21300 (Pakistan); Bouafia, Farida [LMPM, Mechanical Engineering Department, University of Sidi Bel Abbes, Sidi Bel Abbes 22000 (Algeria)

    2014-05-01

    The molecular dynamics (MD) technique based on semi-empirical potentials, is used to carry out the diffusion of Cu- and Ag-trimer on Cu- and Ag(111) surface at 300, 500 and 700 K temperatures. The constant energy MD simulation elaborates the anharmonic effects at the surface such as fissures, dislocations and vacancy creation, in the presence of island. The fissures and dislocations formed are in the range of 1.5–4 Å and 1–7 Å, respectively, from the island's position. The Cu and Ag islands both diffuse easily on Cu(111) surface, manipulate that the trend of diffusion is faster on Cu surface as compared to Ag surface. The process of breaking and opening of the island has also been observed. Moreover, a surface atom popped-up at 700 K by creating a vacancy near the Cu island on Ag surface. The rate of diffusion increases with the increase in temperature, both for homo- and hetero-cases.

  8. van der Waals-corrected Density Functional Theory simulation of adsorption processes on noble-metal surfaces: Xe on Ag(111), Au(111), and Cu(111)

    CERN Document Server

    Silvestrelli, Pier Luigi

    2016-01-01

    The DFT/vdW-WF2s1 method based on the generation of localized Wannier functions, recently developed to include the van der Waals interactions in the Density Functional Theory and describe adsorption processes on metal surfaces by taking metal-screening effects into account, is applied to the case of the interaction of Xe with noble-metal surfaces, namely Ag(111), Au(111), and Cu(111). The study is also repeated by adopting the DFT/vdW-QHO-WF variant relying on the Quantum Harmonic Oscillator model which describes well many-body effects. Comparison of the computed equilibrium binding energies and distances, and the $C_3$ coefficients characterizing the adatom-surface van der Waals interactions, with available experimental and theoretical reference data shows that the methods perform well and elucidate the importance of properly including screening effects. The results are also compared with those obtained by other vdW-corrected DFT schemes, including PBE-D, vdW-DF, vdW-DF2, rVV10, and by the simpler Local Dens...

  9. Quantum mechanics capacitance molecular mechanics modeling of core-electron binding energies of methanol and methyl nitrite on Ag(111) surface

    Science.gov (United States)

    Löytynoja, T.; Li, X.; Jänkälä, K.; Rinkevicius, Z.; Ågren, H.

    2016-07-01

    We study a newly devised quantum mechanics capacitance molecular mechanics (QMCMM) method for the calculation of core-electron binding energies in the case of molecules adsorbed on metal surfaces. This yet untested methodology is applied to systems with monolayer of methanol/methyl nitrite on an Ag(111) surface at 100 K temperature. It was found out that the studied C, N, and O 1s core-hole energies converge very slowly as a function of the radius of the metallic cluster, which was ascribed to build up of positive charge on the edge of the Ag slab. Further analysis revealed that an extrapolation process can be used to obtain binding energies that deviated less than 0.5 eV against experiments, except in the case of methanol O 1s where the difference was as large as 1.8 eV. Additional QM-cluster calculations suggest that the latter error can be connected to the lack of charge transfer over the QM-CMM boundary. Thus, the results indicate that the QMCMM and QM-cluster methods can complement each other in a holistic picture of molecule-adsorbate core-ionization studies, where all types of intermolecular interactions are considered.

  10. Quantum mechanics capacitance molecular mechanics modeling of core-electron binding energies of methanol and methyl nitrite on Ag(111) surface.

    Science.gov (United States)

    Löytynoja, T; Li, X; Jänkälä, K; Rinkevicius, Z; Ågren, H

    2016-07-14

    We study a newly devised quantum mechanics capacitance molecular mechanics (QMCMM) method for the calculation of core-electron binding energies in the case of molecules adsorbed on metal surfaces. This yet untested methodology is applied to systems with monolayer of methanol/methyl nitrite on an Ag(111) surface at 100 K temperature. It was found out that the studied C, N, and O 1s core-hole energies converge very slowly as a function of the radius of the metallic cluster, which was ascribed to build up of positive charge on the edge of the Ag slab. Further analysis revealed that an extrapolation process can be used to obtain binding energies that deviated less than 0.5 eV against experiments, except in the case of methanol O 1s where the difference was as large as 1.8 eV. Additional QM-cluster calculations suggest that the latter error can be connected to the lack of charge transfer over the QM-CMM boundary. Thus, the results indicate that the QMCMM and QM-cluster methods can complement each other in a holistic picture of molecule-adsorbate core-ionization studies, where all types of intermolecular interactions are considered. PMID:27421423

  11. Exploring Ag(111) Substrate for Epitaxially Growing Monolayer Stanene: A First-Principles Study

    Science.gov (United States)

    Gao, Junfeng; Zhang, Gang; Zhang, Yong-Wei

    2016-07-01

    Stanene, a two-dimensional topological insulator composed of Sn atoms in a hexagonal lattice, is a promising contender to Si in nanoelectronics. Currently it is still a significant challenge to achieve large-area, high-quality monolayer stanene. We explore the potential of Ag(111) surface as an ideal substrate for the epitaxial growth of monolayer stanene. Using first-principles calculations, we study the stability of the structure of stanene in different epitaxial relations with respect to Ag(111) surface, and also the diffusion behavior of Sn adatom on Ag(111) surface. Our study reveals that: (1) the hexagonal structure of stanene monolayer is well reserved on Ag(111) surface; (2) the height of epitaxial stanene monolayer is comparable to the step height of the substrate, enabling the growth to cross the surface step and achieve a large-area stanene; (3) the perfect lattice structure of free-standing stanene can be achieved once the epitaxial stanene monolayer is detached from Ag(111) surface; and finally (4) the diffusion barrier of Sn adatom on Ag(111) surface is found to be only 0.041 eV, allowing the epitaxial growth of stanene monolayer even at low temperatures. Our above revelations strongly suggest that Ag(111) surface is an ideal candidate for growing large-area, high-quality monolayer stanene.

  12. Monolayer solid of N-2/Ag(111)

    DEFF Research Database (Denmark)

    Bruch, L.W.; Hansen, Flemming Yssing

    1998-01-01

    An incommensurate monolayer solid of N-2/Ag(111) is modeled using extensive molecular-dynamics simulations. The conditions treated range from the low-temperature orientationally ordered solid to the melting of the solid. The properties are evaluated as a function of spreading pressure. Comparison...

  13. Self-assembled structures of 4‧-([2,2‧:6‧,2″-terpyridine]-4‧-yl)-[1,1‧-phenyl]-4-carboxylic acid molecules induced by metal atoms on ag(111) surface

    Science.gov (United States)

    Ling, Jie; Lu, Yan; Liu, Lacheng; Liu, Xiaoqing; Wang, Li

    2016-07-01

    The self-assembled supramolecular structures of 4‧-([2,2‧:6‧,2″-terpyridine]-4‧-yl)-[1,1‧-phenyl]-4-carboxylic acid (Y) molecules on Ag(111) surface induced by metal elements have been studied by scanning tunneling microscopy. After annealing, the as-deposited monolayer of Y molecules shows four kinds of well-ordered structures due to the competition between dipole interaction, hydrogen bonding and Van der Waals interaction. Introduced Cu atoms drive ordered monolayer into a self-assembled supramolecular structure with bright spots. Deposited Ag atoms cause the monolayer change to a windmill shape self-assembled supramolecular structure. Though the Cu and Ag are in the same group of the periodic table, a Cu atom connects two COOH groups and an Ag atom trends to bind to three COOH groups during the formation of metal-organic bonding within both induced structures. Such result suggests that the self-assembled structures formed by metal-organic coordination bonding can be controlled by choosing the number of metal-organic coordination bonds, which can be helpful to design metal-organic molecular architectures comprising functional building blocks.

  14. 2PPE measurements of PTCDA on Ag(111)

    Energy Technology Data Exchange (ETDEWEB)

    Schwalb, Christian; Hoefer, Ulrich [Fachbereich Physik und Zentrum fuer Materialwissenschaften, Philipps-Universitaet Marburg, D-35032 Marburg (Germany); Sachs, Soenke; Schoell, Achim; Umbach, Eberhard [Universitaet Wuerzburg, Experimentelle Physik II, D- 97074 Wuerzburg (Germany)

    2007-07-01

    Electron transfer at a metal-molecule interface plays an important role in many chemical disciplines, ranging from molecular electronics to surface photochemistry. We present measurements using time-resolved two-photon photoemission (2PPE) to probe the energetics and dynamics of electronically excited states in epitaxial 3,4,9,10perylenetetracarboxylic acid-dianhydride (PTCDA) thin films on a Ag(111) surface for a thickness range from one to ten monolayers. These measurements allow the identification and determination of the energetic positions for the lowest unoccupied molecular orbital (LUMO), and LUMO+1. Angle-resolved 2PPE-measurements show a weak dispersion for the LUMO of {proportional_to}150 meV. Our experiments indicate that the excitation process for the LUMO is mainly done by electrons from the Ag(111) substrate. Time-resolved measurements probing the dynamics of the system show an increasing of lifetime for the LUMO for increasing layer thickness from 40 to 80 fs.

  15. The instability of silicene on Ag(111)

    Energy Technology Data Exchange (ETDEWEB)

    Acun, A.; Poelsema, B.; Zandvliet, H. J. W.; Gastel, R. van [Physics of Interfaces and Nanomaterials, MESA Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede (Netherlands)

    2013-12-23

    We have used low energy electron microscopy to directly visualize the formation and stability of silicene layers on a Ag(111) substrate. Theoretical calculations call into question the stability of this graphene-like analog of silicon. We find that silicene layers are intrinsically unstable against the formation of an “sp{sup 3}-like” hybridized, bulk-like silicon structure. The irreversible formation of this bulk-like structure is triggered by thermal Si adatoms that are created by the silicene layer itself. To add injury to insult, this same instability prevents the formation of a fully closed silicene layer or a thicker bilayer, rendering the future large-scale fabrication of silicene layers on Ag substrates unlikely.

  16. The dissolution of Ag(111) electrodes investigated by in situ scanning tunnelling microscopy

    CERN Document Server

    Wilson, T K

    1998-01-01

    voltammetric methods. This remained evident for varying extents of silver dissolution. Ag(111) electrodes were oxidised in 0.1 M KCIO sub 4 solutions by a single swept ORC of 0.77x10 sup - sup 3 C cm sup - sup 2. The final rest potential of the Ag(111) working electrode was over the potential range of -36 mV to 114 mV versus the SCE where the silver islands of the reformed surface are believed to be unstable. Results show that a majority of silver islands of all sizes are stable with time, whereas the silver islands with irregular shapes tended to evolve to exhibit higher degrees of spherical geometry. Additionally, the position of the silver islands did not remain constant during the acquisition of STM images. Results from in situ STM demonstrated that the underlying step-terrace morphology of the Ag(111) electrodes did not remain constant with time. Both macroscale and nanoscale changes to the Ag(111) electrode surface were observed. It is concluded that this is due to the transport of material along and fr...

  17. Raman analysis of first monolayers of PTCDA on Ag(111)

    International Nuclear Information System (INIS)

    We present a Raman spectroscopic analysis of the bonding properties of organic molecules on Ag(111) surfaces as a model system for organic semiconductor/metal contacts. The planar molecule 3,4,9,10-perylene-tetracarboxylicacid-dianhydride (PTCDA) is used in the present study due to its high electronic mobility and thermal stability. Vibrational signatures of the first monolayer in direct contact with the metal, especially the modes at 1310 and 1575 cm-1, are found to be shifted to lower frequencies. First principles calculations result in corresponding mode patterns, which are essentially located in the centre of the molecule thus indicating the area, where major metal interaction takes place. Furthermore, upon annealing at 450 K the vibrational frequencies of the second monolayer are modified with respect to bulk PTCDA, which reflect particular changes of the bonding situation of this layer. For subsequent layers bulk-like behaviour is observed

  18. Investigation of unoccupied electronic states in PTCDA/Ag(111)

    Energy Technology Data Exchange (ETDEWEB)

    Sachs, Soenke; Krause, Stefan; Schoell, Achim [Universitaet Wuerzburg (Germany). Experimentelle Physik II; Schwalb, Christian; Marks, Manuel; Hoefer, Ulrich [Universitaet Marburg (Germany). Fachbereich Physik; Umbach, Eberhard [Universitaet Wuerzburg (Germany). Experimentelle Physik II; Forschungszentrum Karlsruhe (Germany)

    2008-07-01

    Energetics, momentum and time evolution of electronic states in organic semiconductors and at their interfaces are fundamental properties that strongly determine the performance in electronic applications. All of these properties can be explored with two-photon photoelectron (2PPE) spectroscopy for occupied and in particular for unoccupied electronic states. In the archetypal system perylene-tetracarboxylic-dianhydride (PTCDA) on single crystal Ag(111) surfaces considerable differences between the electronic states of chemisorbed monolayer films and multilayer films are eminent. These differences, which are due to the altered chemical environment of PTCDA- and as well Ag-derived states in the vicinity of the interface, can be tracked with 2PPE. A new unoccupied interface state at the Ag/PTCDA interface with a free-electron like dispersion and comparatively short lifetime is detected that influences the charge injection characteristics considerably. The results of the 2PPE spectroscopy are compared to the results of complementary spectroscopies like UPS, IPES, and STS.

  19. Imaging and manipulation of a polar molecule on Ag(111)

    DEFF Research Database (Denmark)

    Lin, R.; Braun, K.F.; Tang, H.;

    2001-01-01

    A scanning tunneling microscope (STM) was applied to image and laterally manipulate isolated phosphangulene molecules on Ag(111) at 6 K. Atomic-resolution images clearly revealed three characteristic types of appearances (three-lobed, fish and bump shape) for the adsorbed molecules, which could...... correspond to three distinct binding configurations. From a detailed analysis of the relative distance between neighboring three-lobed molecules we determine the adsorption site. Applying the lateral manipulation technique ws demonstrate that the molecule can be pulled, slid or pushed by the tip on the...... surface. Accompanying with the reposition, molecular rotation and/or changing of binding configurations can also be induced. It is found that the dipole moment of the molecule has minor effects on its lateral movement. The results demonstrate that due to many degrees of freedom for large molecules! their...

  20. Imaging and manipulation of a polar molecule oil Ag(111)

    DEFF Research Database (Denmark)

    Lin, Rong; Braun, K.F.; Tang, H.;

    2001-01-01

    A scanning tunneling microscope (STM) was applied to image and laterally manipulate isolated phosphangulene molecules on Ag(111) at 6 K. Atomic-resolution images clearly revealed three characteristic types of appearances (three-lobed, fish and bump shape) for the adsorbed molecules, which could...... correspond to three distinct binding configurations. From a detailed analysis of the relative distance between neighboring three-lobed molecules we determine the adsorption site. Applying the lateral manipulation technique ws demonstrate that the molecule can be pulled, slid or pushed by the tip on the...... surface. Accompanying with the reposition, molecular rotation and/or changing of binding configurations can also be induced. It is found that the dipole moment of the molecule has minor effects on its lateral movement. The results demonstrate that due to many degrees of freedom for large molecules! their...

  1. Ab initio study of origin and properties of a metal-organic interface state of the PTCDA/Ag(111) system

    OpenAIRE

    Zaitsev, N. L.; Nechaev, I. A.; P. M. Echenique; Chulkov, E. V.

    2010-01-01

    We present a detailed study of a monolayer film of 3,4,9,10-perylene-tetracarboxylic acid dianhydride (PTCDA) on Ag(111) (the PTCDA/Ag(111) system). The study is done within density functional theory with the use of the periodic slab model. The slab is chosen to contain a PTCDA monolayer film on a silver thin film of different thicknesses (6, 9, and 12 layers) with the (111) orientation. We show that one of two surface states of the pure Ag(111) films transforms into an unoccupied interface s...

  2. Atomic structure of "multilayer silicene" grown on Ag(111): Dynamical low energy electron diffraction analysis

    Science.gov (United States)

    Kawahara, Kazuaki; Shirasawa, Tetsuroh; Lin, Chun-Liang; Nagao, Ryo; Tsukahara, Noriyuki; Takahashi, Toshio; Arafune, Ryuichi; Kawai, Maki; Takagi, Noriaki

    2016-09-01

    We have investigated the atomic structure of the "multilayer silicene" grown on the Ag(111) single crystal surface by using low energy electron diffraction (LEED) and scanning tunneling microscopy (STM). We measured the intensity of the LEED spot as a function of the incident electron energy (I-V curve) and analyzed the I-V curve using a dynamical LEED theory. We have found that the Si(111)(√{ 3} ×√{ 3})-Ag model well reproduces the I-V curve whereas the models consisting of the honeycomb structure of Si do not. The bias dependence of the STM image of multilayer silicene agrees with that of the Si(111)(√{ 3} ×√{ 3})-Ag reconstructed surface. Consequently, we have concluded that the multilayer silicene grown on Ag(111) is identical to the Si(111)(√{ 3} ×√{ 3})-Ag reconstructed structure.

  3. Two-dimensional pentacene:3,4,9,10-perylenetetracarboxylic dianhydride supramolecular chiral networks on Ag(111).

    Science.gov (United States)

    Chen, Wei; Li, Hui; Huang, Han; Fu, Yuanxi; Zhang, Hong Liang; Ma, Jing; Wee, Andrew Thye Shen

    2008-09-17

    Self-assembly of the binary molecular system of pentacene and 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) on Ag(111) has been investigated by low-temperature scanning tunneling microscopy, molecular dynamics (MD), and density functional theory (DFT) calculations. Well-ordered two-dimensional (2D) pentacene:PTCDA supramolecular chiral networks are observed to form on Ag(111). The 2D chiral network formation is controlled by the strong interfacial interaction between adsorbed molecules and the underlying Ag(111), as revealed by MD and DFT calculations. The registry effect locks the adsorbed pentacene and PTCDA molecules into specific adsorption sites due to the corrugation of the potential energy surface. The 2D supramolecular networks are further constrained through the directional CO...H-C multiple intermolecular hydrogen bonding between the anhydride groups of PTCDA and the peripheral aromatic hydrogen atoms of the neighboring pentacene molecules. PMID:18722423

  4. Magnetic and electronic structure of Mn nanostructures on Ag(111) and Au(111)

    Science.gov (United States)

    Cardias, R.; Bezerra-Neto, M. M.; Ribeiro, M. S.; Bergman, A.; Szilva, A.; Eriksson, O.; Klautau, A. B.

    2016-01-01

    We present results of the electronic and magnetic structure of Mn nanowires adsorbed on Ag(111) and Au(111) surfaces. For finite Mn nanowires on Ag(111) and Au(111) surfaces, our ab initio results show that the large difference between the spin-orbit splitting of these two surfaces leads to completely different magnetic configurations. The magnetic ordering for Mn nanowires adsorbed on Ag(111) is governed by the strong exchange interaction between Mn adatoms. For Mn nano-chains on Au(111), the competition between Heisenberg and Dzyaloshinskii-Moriya interactions leads to a complex magnetic structure of the clusters considered here. Among the more conspicuous results we note a spin-spiral helical type for the nanowire with seven atoms, and a complex magnetic configuration incommensurate with the substrate lattice for a double-sized Mn wire. The effect of the structural relaxation is also investigated, showing sensitivity of the exchange interactions to the bond distance to the substrate. We also demonstrate that small changes in the band filling of these Mn chains results in drastically different changes of the interatomic exchange. Finally, we show that dispersion of the electronic energy spectrum is possible even in nanostructures with bounded spatial extension.

  5. Electron dynamics at the PTCDA/Ag(111) interface studied with 2PPE

    Energy Technology Data Exchange (ETDEWEB)

    Marks, Manuel; Schwalb, Christian; Hoefer, Ulrich [Fachbereich Physik und Zentrum fuer Materialwissenschaften, Philipps-Universitaet Marburg (Germany); Sachs, Soenke; Schoell, Achim [Universitaet Wuerzburg (Germany). Experimentelle Physik II; Umbach, Eberhard [Universitaet Wuerzburg (Germany). Experimentelle Physik II; Forschungszentrum Karlsruhe (Germany)

    2008-07-01

    We investigated epitaxial grown PTCDA (3,4,9,10-perylene-tetracarboxylic acid-dianhydride) on the Ag(111) surface as model system for a metal-organic interface by means of time- and angle-resolved two-photon photoemission (2PPE). In the presence of thin PTCDA films, an unoccupied state with an effective electron mass of 0.39 m{sub e} is observed in the projected band gap of Ag 0.6 eV above E{sub F}. Its inelastic electronic lifetime is {approx_equal}50 fs and the state has an appreciable metallic character, significantly exceeding that of the image-potential states. We assign the new state to a mixture of the former Ag(111) Shockley surface state and the LUMO+1 of the first PTCDA monolayer (ML). In contrast to this interface state, which changes only weakly with PTCDA coverage, the binding energy of the first image-potential state shows a strong dependence. It increases by 135 meV for 1 ML, compared to clean Ag(111), but with absorption of the second ML, a subsequent drop of -70 meV relative to the clean surface occurs. A similar coverage dependence can be seen in the effective electron mass, which decreases by 20% from the first to the second PTCDA layer.

  6. From hydrogen bonding to metal coordination and back: Porphyrin-based networks on Ag(111).

    Science.gov (United States)

    Studener, F; Müller, K; Marets, N; Bulach, V; Hosseini, M W; Stöhr, M

    2015-03-14

    The self-assembly of a metal-free porphyrin bearing two pyridyl coordinating sites and two pentyl chains at trans meso positions was investigated under ultrahigh vacuum on a Ag(111) surface by scanning tunneling microscopy (STM). The STM measurements revealed a well-ordered close-packed structure with a rhombic unit cell for coverages ≤1 monolayer with their molecular plane parallel to the surface. The growth direction of the molecular islands is aligned along the step edges, which are restructured due to molecule-substrate interactions. The shorter unit cell vector of the molecular superstructure follows the〈1-10〉direction of the Ag(111) substrate. Hydrogen bonds between pyridyl and pyrrole groups of neighboring molecules as well as weak van der Waals forces between the pentyl chains stabilize the superstructure. Deposition of cobalt atoms onto the close-packed structure at room temperature leads to the formation of a hexagonal porous network stabilized by metal-ligand bonding between the pyridyl ligands and the cobalt atoms. Thermal annealing of the Co-coordination network at temperatures >450 K results in the transformation of the hexagonal network into a second close-packed structure. Changes in the molecule-substrate interactions due to metalation of the porphyrin core with Co as well as intermolecular interactions can explain the observed structural transformations. PMID:25770515

  7. Electron spectroscopy of organic heterointerfaces: SnPc/PTCDA/Ag(111)

    Energy Technology Data Exchange (ETDEWEB)

    Greif, Michael; Haeming, Marc; Wiessner, Michael; Schoell, Achim [Universitaet Wuerzburg, Experimentelle Physik VII, D-97074 Wuerzburg (Germany); Reinert, Friedrich [Universitaet Wuerzburg, Experimentelle Physik VII, D-97074 Wuerzburg (Germany); FZK Karlsruhe, Gemeinschaftslabor fuer Nanoanalytik, D-76021 Karlsruhe (Germany)

    2010-07-01

    Heterointerfaces between different organic molecules are an issue of great technologic relevance. However, structurally well-defined ultrathin interfaces which are suited for the investigation with surface sensitive techniques are difficult to prepare. In order to exploit its potential as a model system in this respect we have investigated hetero-layers consisting of tin-phthalocyanine (SnPc) and perylene-tetracarboxylic acid dianhydride (PTCDA) deposited on clean Ag(111) surfaces with photoelectron spectroscopy (XPS and UPS), X-ray absorption and low energy electron diffraction (LEED). The spectroscopic signatures of the two compounds can be distinguished unambiguously in the core and valence spectra. For ultra-thin SnPc layers deposited on a single layer of PTCDA on Ag(111) structural information can be derived from angle resolved XPS and NEXAFS. The data indicates that a closed monomolecular layer of flat lying SnPc is established. This is corroborated by the UPS spectra which show a characteristic splitting of the SnPc HOMO signal due to dimer formation only for SnPc coverages beyond one layer. Moreover, LEED was applied in order to investigate the lateral ordering.

  8. From hydrogen bonding to metal coordination and back: Porphyrin-based networks on Ag(111)

    Energy Technology Data Exchange (ETDEWEB)

    Studener, F., E-mail: f.studener@rug.nl; Müller, K.; Stöhr, M., E-mail: m.a.stohr@rug.nl [Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747AG Groningen (Netherlands); Marets, N.; Bulach, V., E-mail: bulach@unistra.fr; Hosseini, M. W., E-mail: hosseini@unistra.fr [Laboratoire de Tectonique Moléculaire, UMR UDS-CNRS 7140, Université de Strasbourg, 4 rue Blaise Pascal, 67070 Strasbourg (France)

    2015-03-14

    The self-assembly of a metal-free porphyrin bearing two pyridyl coordinating sites and two pentyl chains at trans meso positions was investigated under ultrahigh vacuum on a Ag(111) surface by scanning tunneling microscopy (STM). The STM measurements revealed a well-ordered close-packed structure with a rhombic unit cell for coverages ≤1 monolayer with their molecular plane parallel to the surface. The growth direction of the molecular islands is aligned along the step edges, which are restructured due to molecule-substrate interactions. The shorter unit cell vector of the molecular superstructure follows the 〈1-10〉 direction of the Ag(111) substrate. Hydrogen bonds between pyridyl and pyrrole groups of neighboring molecules as well as weak van der Waals forces between the pentyl chains stabilize the superstructure. Deposition of cobalt atoms onto the close-packed structure at room temperature leads to the formation of a hexagonal porous network stabilized by metal-ligand bonding between the pyridyl ligands and the cobalt atoms. Thermal annealing of the Co-coordination network at temperatures >450 K results in the transformation of the hexagonal network into a second close-packed structure. Changes in the molecule-substrate interactions due to metalation of the porphyrin core with Co as well as intermolecular interactions can explain the observed structural transformations.

  9. From hydrogen bonding to metal coordination and back: Porphyrin-based networks on Ag(111)

    International Nuclear Information System (INIS)

    The self-assembly of a metal-free porphyrin bearing two pyridyl coordinating sites and two pentyl chains at trans meso positions was investigated under ultrahigh vacuum on a Ag(111) surface by scanning tunneling microscopy (STM). The STM measurements revealed a well-ordered close-packed structure with a rhombic unit cell for coverages ≤1 monolayer with their molecular plane parallel to the surface. The growth direction of the molecular islands is aligned along the step edges, which are restructured due to molecule-substrate interactions. The shorter unit cell vector of the molecular superstructure follows the 〈1-10〉 direction of the Ag(111) substrate. Hydrogen bonds between pyridyl and pyrrole groups of neighboring molecules as well as weak van der Waals forces between the pentyl chains stabilize the superstructure. Deposition of cobalt atoms onto the close-packed structure at room temperature leads to the formation of a hexagonal porous network stabilized by metal-ligand bonding between the pyridyl ligands and the cobalt atoms. Thermal annealing of the Co-coordination network at temperatures >450 K results in the transformation of the hexagonal network into a second close-packed structure. Changes in the molecule-substrate interactions due to metalation of the porphyrin core with Co as well as intermolecular interactions can explain the observed structural transformations

  10. Dynamical bi-stability of single-molecule junctions: A combined experimental/theoretical study of PTCDA on Ag(111)

    OpenAIRE

    Brumme, Thomas; Neucheva, Olga; Toher, Cormac; Gutiérrez, Rafael; Weiss, Christian; Temirov, Ruslan; Greuling, Andreas; Kaczmarski, Marcin; Rohlfing, Michael; Tautz, Stefan; Cuniberti, Gianaurelio

    2010-01-01

    The dynamics of a molecular junction consisting of a PTCDA molecule between the tip of a scanning tunneling microscope and a Ag(111) surface have been investigated experimentally and theoretically. Repeated switching of a PTCDA molecule between two conductance states is studied by low-temperature scanning tunneling microscopy for the first time, and is found to be dependent on the tip-substrate distance and the applied bias. Using a minimal model Hamiltonian approach combined with density-fun...

  11. Dynamical bistability of single-molecule junctions: A combined experimental and theoretical study of PTCDA on AG(111)

    OpenAIRE

    Brumme, T.; Neucheva, O.A.; Cuniberti, G.; Toher, C.; Gutiérrez, R.; Weiss, C.(Theory Center, Jefferson Lab, Newport News, VA, 23606, U.S.A.); Temirov, R.; Greuling, A.; M. Kaczmarski; Rohlfing, M.; Tautz, F. S.

    2011-01-01

    The dynamics of a molecular junction consisting of a PTCDA molecule between the tip of a scanning tunneling microscope and a Ag(111) surface have been investigated experimentally and theoretically. Repeated switching of a PTCDA molecule between two conductance states is studied by low-temperature scanning tunneling microscopy for the first time and is found to be dependent on the tip-substrate distance and the applied bias. Using a minimal model Hamiltonian approach combined with density-func...

  12. The nature of the observed free-electron-like state in a PTCDA monolayer on Ag(111)

    OpenAIRE

    Dyer, Matthew S.; Persson, Mats

    2009-01-01

    A free-electron like band has recently been observed in a monolayer of PTCDA (3,4,9,10-perylene tetracarboxylic dianhydride) molecules on Ag(111) by two-photon photoemission [Schwalb et al., Phys. Rev. Lett. 101, 146801 (2008)] and scanning tunneling spectroscopy [Temirov et al., Nature 444, 350 (2006)]. Using density functional theory calculations, we find that the observed free-electron like band originates from the Shockley surface state band being dramatically shifted up in energy by the ...

  13. Current-induced switching of PTCDA on Ag(111)

    Energy Technology Data Exchange (ETDEWEB)

    Neucheva, Olga; Weiss, Christian; Temirov, Ruslan; Tautz, Frank Stefan [Institut fuer Bio- und Nanosysteme (IBN-3), Forschungszentrum Juelich, 52425 Juelich (Germany); JARA-Fundamental of Future Information Technology, Forschungszentrum Juelich, 52425 Juelich (Germany)

    2009-07-01

    A low temperature scanning tunneling microscope (LT-STM) has been used to investigate electron transport through a single PTCDA molecule on Ag(111). Under certain conditions, one of the carboxylic oxygen atoms of the PTCDA molecule establishes a chemical bond with the STM tip, forming a covalently bound single molecular junction. In this contribution, we investigate the process of contact formation as a function of parameters such as distance, bias voltage and electrical current through the molecular junction. In a narrow distance and voltage interval, bistable switching of the oxygen atom between a high- and low-conductance state is observed. The implications of this observation are discussed.

  14. Electronic structure of ultra thin organic hetero-interfaces - SnPc/PTCDA/Ag(111)

    Energy Technology Data Exchange (ETDEWEB)

    Schoell, Achim; Haeming, Marc; Greif, Michael; Wiessner, Michael [Universitaet Wuerzburg, Experimentelle Physik VII, D-97074 Wuerzburg (Germany); Reinert, Friedrich [Universitaet Wuerzburg, Experimentelle Physik VII, D-97074 Wuerzburg (Germany); Karlsruhe Institute of Technology, Gemeinschaftslabor fuer Nanoanalytik, D-76021 Karlsruhe (Germany)

    2010-07-01

    While the interfaces of molecules to a substrate have been studied extensively, knowledge about the interface between different molecular compounds is still relatively scarce. This is to some extend caused by the fact that these interfaces, which are of great relevance for opto-electronic devices consisting out of multiple organic compounds, are more complicated to access experimentally. Structurally well defined model systems, which allow for a systematic and detailed investigation of the interface characteristics, are thus of great importance. In this work we provide data from x-ray absorption and photoelectron spectroscopy on the organic heterolayer system tin-phthalocyanine (SnPc)/perylen-tetracarboxylicacid dianhydride (PTCDA). We show, that SnPc, prepared on a Ag(111) surface precovered by a monolayer of PTCDA, forms a well defined interface with a closed first layer of flat lying molecules. Moreover, the bonding of the SnPc molecules to the PTCDA interlayer is clearly non-covalent and a detailed inspection of the valence spectra shows that the respective molecular signatures can be distinguished well. The SnPc/PTCDA/Ag(111) system is thus well-suited for further investigations employing complicated techniques.

  15. Band structure of hydrogenated silicene on Ag(111): Evidence for half-silicane

    Science.gov (United States)

    Wang, W.; Olovsson, W.; Uhrberg, R. I. G.

    2016-02-01

    In the case of graphene, hydrogenation removes the conductivity due to the bands forming the Dirac cone by opening up a band gap. This type of chemical functionalization is of the utmost importance for electronic applications. As predicted by theoretical studies, a similar change in the band structure is expected for silicene, the closest analog to graphene. We here report a study of the atomic and electronic structures of hydrogenated silicene with hydrogen on one side, the so-called half-silicane. The ("2 √{3 }×2 √{3 } ") phase of silicene on Ag(111) was used in this Rapid Communication since it can be formed homogeneously across the entire surface of the Ag substrate. Low-energy electron diffraction and scanning tunneling microscopy data clearly show that hydrogenation changes the structure of silicene on Ag(111) resulting in a (1 × 1) periodicity with respect to the silicene lattice. The hydrogenated silicene also exhibits a quasiregular (2 √{3 }×2 √{3 } )-like arrangement of vacancies. Angle-resolved photoelectron spectroscopy revealed two dispersive bands which can be unambiguously assigned to half-silicane. The common top of these bands is located at ˜0.9 eV below the Fermi level. We find that the experimental bands are closely reproduced by the theoretical band structure of free-standing silicene with H adsorbed on the upper hexagonal sublattice.

  16. DFT study of PTCDA on Ag(111) including a STM tip

    Energy Technology Data Exchange (ETDEWEB)

    Greuling, Andreas; Kaczmarski, Marcin; Rohlfing, Michael [Universitaet Osnabrueck, Fachbereich Physik, Barbarastrasse 7, 49069 Osnabrueck (Germany)

    2010-07-01

    Any progress in the field of molecular electronics requires a detailed knowledge of conduction through molecules. As a prerequisite, detailed knowledge of the geometrical structure of a model system like the system PTCDA on Ag(111) probed with a STM tip is of big importance. In experiment it is possible to peel the PTCDA from the surface by using a STM tip above a corner oxygen atom. Furthermore, the molecule flips from the surface to the tip and back under certain tip-surface distance and voltage conditions. Here, we investigate these mechanisms by employing ab initio calculations applying the widely used SIESTA code. Using Density Functional Theory (DFT) in the Local Density Approximation (LDA) we present calculated geometries for the process of peeling of the molecule. Additionally we show tip-surface interaction potentials also considering the influence of a homogeneous electrical field.

  17. Polymorphism in Self-Assembled Structures of 9-Anthracene Carboxylic Acid on Ag(111

    Directory of Open Access Journals (Sweden)

    Bo Xu

    2012-06-01

    Full Text Available Surface self-assembly process of 9-anthracene carboxylic acid (AnCA on Ag(111 was investigated using STM. Depending on the molecular surface density, four spontaneously formed and one annealed AnCA ordered phases were observed, namely a straight belt phase, a zigzag double-belt phase, two simpler dimer phases, and a kagome phase. The two high-density belt phases possess large unit cells on the scale length of 10 nm, which are seldom observed in molecular self-assembled structures. This structural diversity stems from a complicated competition of different interactions of AnCA molecules on metal surface, including intermolecular and molecular-substrate interactions, as well as the steric demand from high molecular surface density.

  18. Light emission from Ag(111) driven by inelastic tunneling in the field emission regime.

    Science.gov (United States)

    Martínez-Blanco, Jesús; Fölsch, Stefan

    2015-07-01

    We study the light emission from a Ag(111) surface when the bias voltage on a scanning tunneling microscope (STM) junction is ramped into the field emission regime. Above the vacuum level, scanning tunneling spectroscopy (STS) shows a series of well defined resonances associated with the image states of the surface, which are Stark shifted due to the electric field provided by the STM tip. We present photon-energy resolved measurements that unambiguously show that the mechanism for light emission is the radiative decay of surface localized plasmons excited by the electrons that tunnel inelastically into the Stark shifted image states. Our work illustrates the effect of the tip radius both in the STS spectrum and the light emission maps by repeating the experiment with different tips. PMID:26045477

  19. Slow positron studies on single crystals of Ag(100), Ag(111) and Cu(111)

    International Nuclear Information System (INIS)

    Monoenergetic positrons were employed to examine positronium formation as a function of sample temperature (300 to 1200 K) and incident energy (0 to 5 keV) on Ag(100), Ag(111) and Cu(111) surfaces with submonolayer contamination. In these metals at the higher temperatures, positronium formation becomes the dominant process. A one-dimensional diffusion model is fit to the data as a function of incident energy. Th positronium fraction is found to be an activated process and is identified as detrapping from a surface state and an estimate of the depth of this trap is extracted. The diffusion length is found to be temperature independent before the onset of vacancy trapping. At the higher temperatures vacancy trapping is observed by the decrease in the positron diffusion length at the higher incident voltages. A vacancy formation energy is extracted from the data and is generally lower than the accepted bulk values. 18 references

  20. Investigation of the electron dynamics at the PTCDA/Ag(111)-interface; Untersuchung der Elektronendynamik an der PTCDA-Ag (111) - Grenzflaeche

    Energy Technology Data Exchange (ETDEWEB)

    Schwalb, Christian

    2008-12-17

    In this work the electron dynamics at the PTCDA/Ag(111) interface have been studied with time- and angleresolved Two-photon photoemission (2PPE) as well as time-resolved photoluminescence (PL). The first part of this work concentrates on the characterization of an unoccupied electronic state, that develops 0.6 eV above the Fermi level due to the adsorption of the PTCDA molecules, whereas the shockley surface state of the clean surface vanishes. The measurements clearly identify this state as an interface state that is located between the metal surface and the first layer of the molecules. Dispersion measurements yield an effective mass of this state of 0.39 m{sub e} at the Gamma-point and show backfolding at the zone boundaries of the rectangular PTCDA unit cell. Time-resolved measurements show a surprisingly short lifetime of t=54 fs, clearly indicating a strong coupling of the state with the metal. This behaviour can be explained by a shift of the shockley surface state. This for the clean Ag(111)-surface normally occupied state shifts above the Fermi level because of the highly polarizable PTCDA molecules. Calculations with a one dimensional model potential support this interpretation. Angleresolved lifetime measurements as a function of parallel momentum show a correlation of the decay dynamics of the interface state with the measured bandstructure. The observed drop of the lifetime for larger parallel momentum is significantly smaller as expected for the pure shockley state. This behaviour can be explained due to a hybridisation of the shockley state with the LUMO+1 of the first PTCDA monolayer for k parallel >>0. The second part of this work deals with the intramolecular excitation at the PTCDA/Ag(111) interface after excitation with laser pulses with 2.33 eV and 4.66 eV photon energy. Time-resolved photoluminescence measurements show a strong rise in the PL-lifetime as a function of PTCDA coverage, that can be explained by an increase in the crystallinity of

  1. Two-photon Photoemission of Organic Semiconductor Molecules on Ag(111)

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Aram [Univ. of California, Berkeley, CA (United States)

    2008-05-01

    Angle- and time-resolved two-photon photoemission (2PPE) was used to study systems of organic semiconductors on Ag(111). The 2PPE studies focused on electronic behavior specific to interfaces and ultrathin films. Electron time dynamics and band dispersions were characterized for ultrathin films of a prototypical n-type planar aromatic hydrocarbon, PTCDA, and representatives from a family of p-type oligothiophenes.In PTCDA, electronic behavior was correlated with film morphology and growth modes. Within a fewmonolayers of the interface, image potential states and a LUMO+1 state were detected. The degree to which the LUMO+1 state exhibited a band mass less than a free electron mass depended on the crystallinity of the layer. Similarly, image potential states were measured to have free electron-like effective masses on ordered surfaces, and the effective masses increased with disorder within the thin film. Electron lifetimes were correlated with film growth modes, such that the lifetimes of electrons excited into systems created by layer-by-layer, amorphous film growth increased by orders of magnitude by only a few monolayers from the surface. Conversely, the decay dynamics of electrons in Stranski-Krastanov systems were limited by interaction with the exposed wetting layer, which limited the barrier to decay back into the metal.Oligothiophenes including monothiophene, quaterthiophene, and sexithiophene were deposited on Ag(111), and their electronic energy levels and effective masses were studied as a function of oligothiophene length. The energy gap between HOMO and LUMO decreased with increasing chain length, but effective mass was found to depend on domains from high- or low-temperature growth conditions rather than chain length. In addition, the geometry of the molecule on the surface, e.g., tilted or planar, substantially affected the electronic structure.

  2. Adsorption geometry, conformation, and electronic structure of 2H-octaethylporphyrin on Ag(111) and Fe metalation in ultra high vacuum

    Science.gov (United States)

    Borghetti, Patrizia; Santo, Giovanni Di; Castellarin-Cudia, Carla; Fanetti, Mattia; Sangaletti, Luigi; Magnano, Elena; Bondino, Federica; Goldoni, Andrea

    2013-04-01

    Due to the growing interest in the ferromagnetic properties of Fe-octaethylporphyrins (Fe-OEP) for applications in spintronics, methods to produce stable Fe-porphyrins with no Cl atoms are highly demanded. Here, we demonstrate the formation of Fe-OEP layers on Ag(111) single crystal by the ultra high vacuum in situ metalation of the free-base 2H-2,3,7,8,12,13,17,18-octaethylporphyrin (2H-OEP) molecules. The metalation proceeds exactly as in the case of 2H-5,10,15,20-tetraphenylporphyrin (2H-TPP) on the same substrate. An extensive surface characterization by means of X-ray photoemission spectroscopy, valence band photoemission, and NEXAFS with synchrotron radiation light provides information on molecular conformation and electronic structure in the monolayer and multilayer cases. We demonstrate that the presence of the ethyl groups affects the tilt of the adsorbed molecules, the conformation of the macrocycle, and the polarization screening in multilayers, but has only a minor effect in the metalation process with respect to 2H-TPP.

  3. Manipulation/Extraction of Adatom on a Mound: AG(111)

    International Nuclear Information System (INIS)

    We present results of an extensive study of the manipulation/extraction of an atom from a small Ag mound on Ag(111) using a Ag tip. Molecular dynamics (MD) and molecular static (MS) simulations were carried out using interaction potentials from the embedded atom method. In order to evaluate the manipulation capabilities of the tip, we first examine in detail the characteristics of the energy landscape in the absence of the tip. We find that the energy barrier for the extraction of the Ag atom, either through lateral (sliding downwards) or through vertical (climbing upwards) diffusion, to be about 0.3 eV. We show that the presence of the tip lowers the energy barrier for both lateral and vertical diffusion. We find that when the tip is above the edge of the mound (at a height of 2.43 A A from the Ag atom) the barrier for diffusion drops to 0.032 eV for lateral and 0.18 eV for vertical manipulation. We discuss the effect of the tip shape and geometry on the energetics, and present a detailed explanation of how the adatom is extracted from a mound in good agreement with experimental observations

  4. The nature of the observed free-electron-like state in a PTCDA monolayer on Ag(111)

    Energy Technology Data Exchange (ETDEWEB)

    Dyer, Matthew S; Persson, Mats, E-mail: msd30@liv.ac.u [Surface Science Research Centre, University of Liverpool, Liverpool L69 3BX (United Kingdom)

    2010-06-15

    A free-electron-like band has recently been observed in a monolayer of 3,4,9,10-perylene tetracarboxylic dianhydride (PTCDA) molecules on Ag(111) by two-photon photoemission (Schwalb et al 2008 Phys. Rev. Lett. 101 146801) and scanning tunneling spectroscopy (Temirov et al 2006 Nature 444 350). Using density functional theory calculations, we find that the observed free-electron-like band originates from the Shockley surface state band being dramatically shifted up in energy by the interaction with the adsorbed molecules, while it also acquires a substantial admixture with a molecular band.

  5. The nature of the observed free-electron-like state in a PTCDA monolayer on Ag(111)

    International Nuclear Information System (INIS)

    A free-electron-like band has recently been observed in a monolayer of 3,4,9,10-perylene tetracarboxylic dianhydride (PTCDA) molecules on Ag(111) by two-photon photoemission (Schwalb et al 2008 Phys. Rev. Lett. 101 146801) and scanning tunneling spectroscopy (Temirov et al 2006 Nature 444 350). Using density functional theory calculations, we find that the observed free-electron-like band originates from the Shockley surface state band being dramatically shifted up in energy by the interaction with the adsorbed molecules, while it also acquires a substantial admixture with a molecular band.

  6. Influence of the adsorption geometry of PTCDA on Ag(111) on the tip–molecule forces in non-contact atomic force microscopy

    OpenAIRE

    Gernot Langewisch; Jens Falter; André Schirmeisen; Harald Fuchs

    2014-01-01

    Perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) adsorbed on a metal surface is a prototypical organic–anorganic interface. In the past, scanning tunneling microscopy and scanning tunneling spectroscopy studies of PTCDA adsorbed on Ag(111) have revealed differences in the electronic structure of the molecules depending on their adsorption geometry. In the work presented here, high-resolution 3D force spectroscopy measurements at cryogenic temperatures were performed on a surface area tha...

  7. Butanethiol adsorption and dissociation on Ag (111): A periodic DFT study

    Science.gov (United States)

    Li, Aixiao; Piquemal, Jean-Philip; Richardi, Johannes; Calatayud, Monica

    2016-04-01

    The molecular and dissociative adsorption of butanethiol (C4H9SH) on regular Ag (111) surfaces has been studied by means of periodic ab initio density functional techniques. In molecular form, butanethiol is bound to the surface only by weak polarization-induced forces with the C-S axis tilted by 38° relative to the normal surface. The S atom occupies a position between a hollow fcc and a bridge site. In the dissociative adsorption process, the S-H bond breaks leading to butanethiolate. The S atom of the thiolate also occupies a threefold position, slightly displaced to a hollow fcc site compared to the thiol adsorption case. The C-S axis of the thiolate is tilted by about 37°. The calculated adsorption energies show that the butanethiol and butanethiolate have similar adsorption ability. The computed reaction pathway for the S-H dissociation gives an activation energy of 0.98 eV indicating that the thiolate formation from thiol, although not spontaneous at room temperature, might be feasible on silver surfaces. The dissociation process induces both adsorbate and surface polarization with a significant charge transfer from the substrate to the adsorbate.

  8. Monitoring Si growth on Ag(111) with scanning tunneling microscopy reveals that silicene structure involves silver atoms

    International Nuclear Information System (INIS)

    Using scanning tunneling microscopy (STM), the elaboration of the so-called silicene layer on Ag(111) is monitored in real time during Si evaporation at different temperatures. It is shown that the growth of silicene is accompanied by the release of about 65% of the surface Ag atoms from the Si covered areas. We observe that Si islands develop on the Ag terraces and Si strips at the Ag step edges, progressively forming ordered (4×4), (√(13)×√(13)) R13.9°, and dotted phases. Meanwhile, displaced Ag atoms group to develop additional bare Ag terraces growing round the Si islands from the pristine Ag step edges. This indicates a strong interaction between Si and Ag atoms, with an important modification of the Ag substrate beneath the surface layer. This observation is in contradiction with the picture of a silicene layer weakly interacting with the unreconstructed Ag substrate, and strongly indicates that the structure of silicene on Ag(111) corresponds either to a Si-Ag surface alloy or to a Si plane covered with Ag atoms

  9. Tailoring metal-organic hybrid interfaces: heteromolecular structures with varying stoichiometry on Ag(111)

    Science.gov (United States)

    Stadtmüller, Benjamin; Henneke, Caroline; Soubatch, Serguei; Tautz, F. Stefan; Kumpf, Christian

    2015-02-01

    The physical properties of interfaces between organic semiconductors and metal surfaces crucially influence the performance of organic electronic devices. In order to enable the tailoring of such metal-organic hybrid interfaces we study the adsorption of heteromolecular thin films containing the prototypical molecules copper-II-phthalocyanine (CuPc) and 3,4,9,10-perylene-tetra-carboxylic-dianhydride (PTCDA) on the Ag(111) surface. Here, we demonstrate how the lateral order can be tuned by changing the relative coverage of both adsorbates on the surface. The layer growth has been studied in real time with low energy electron microscopy, and—for different stoichiometries—the geometric properties of three heteromolecular submonolayer phases have been investigated using high resolution low energy electron diffraction and low temperature scanning tunneling microscopy. Furthermore, we have used a theoretical approach based on van der Waals and electrostatic potentials in order to reveal the influence of the intermolecular and the molecule-substrate interactions on the lateral order of heteromolecular films.

  10. Thermal and Electronic Fluctuations of Flexible Adsorbed Molecules: Azobenzene on Ag(111)

    Science.gov (United States)

    Maurer, Reinhard J.; Liu, Wei; Poltavsky, Igor; Stecher, Thomas; Oberhofer, Harald; Reuter, Karsten; Tkatchenko, Alexandre

    2016-04-01

    We investigate the thermal and electronic collective fluctuations that contribute to the finite-temperature adsorption properties of flexible adsorbates on surfaces on the example of the molecular switch azobenzene C12 H10 N2 on the Ag(111) surface. Using first-principles molecular dynamics simulations, we obtain the free energy of adsorption that accurately accounts for entropic contributions, whereas the inclusion of many-body dispersion interactions accounts for the electronic correlations that govern the adsorbate binding. We find the adsorbate properties to be strongly entropy driven, as can be judged by a kinetic molecular desorption prefactor of 1024 s-1 that largely exceeds previously reported estimates. We relate this effect to sizable fluctuations across structural and electronic observables. A comparison of our calculations to temperature-programed desorption measurements demonstrates that finite-temperature effects play a dominant role for flexible molecules in contact with polarizable surfaces, and that recently developed first-principles methods offer an optimal tool to reveal novel collective behavior in such complex systems.

  11. Reactivity of Ultra-Thin ZnO Films Supported by Ag(111) and Cu(111): A Comparison to ZnO/Pt(111)

    OpenAIRE

    Pan, Q.; B. Liu; McBriarty, M.; Martynova, Y.; Groot, I. de; Wang, S.; Bedzyk, M.; Shaikhutdinov, S.; Freund, H.

    2014-01-01

    We studied structure and reactivity of ZnO(0001) ultrathin films grown on Ag(111) and Cu(111) single crystal surfaces. Structural characterization was carried out by scanning tunneling microscopy, Auger electron spectroscopy, low-energy electron diffraction, and temperature programmed desorption. The CO oxidation behavior of the films was studied at low temperature (450 K) at near atmospheric pressures using gas chromatography. For ZnO/Cu(111), it is shown that under reaction conditions ZnO r...

  12. Growth and ordering of Ni(II) diphenylporphyrin monolayers on Ag(111) and Ag/Si(111) studied by STM and LEED

    International Nuclear Information System (INIS)

    The room temperature self-assembly and ordering of (5,15-diphenylporphyrinato)nickel(II) (NiDPP) on the Ag(111) and Ag/Si(111)-(√3 × √3)R30° surfaces have been investigated using scanning tunnelling microscopy and low-energy electron diffraction. The self-assembled structures and lattice parameters of the NiDPP monolayer are shown to be extremely dependent on the reactivity of the substrate, and probable molecular binding sites are proposed. The NiDPP overlayer on Ag(111) grows from the substrate step edges, which results in a single-domain structure. This close-packed structure has an oblique unit cell and consists of molecular rows. The molecules in adjacent rows are rotated by approximately 17° with respect to each other. In turn, the NiDPP molecules form three equivalent domains on the Ag/Si(111)-(√3 × √3)R30° surface, which follow the three-fold symmetry of the substrate. The molecules adopt one of three equivalent orientations on the surface, acting as nucleation sites for these domains, due to the stronger molecule-substrate interaction compared to the case of the Ag(111). The results are explained in terms of the substrate reactivity and the lattice mismatch between the substrate and the molecular overlayer. (paper)

  13. Growth and ordering of Ni(II) diphenylporphyrin monolayers on Ag(111) and Ag/Si(111) studied by STM and LEED.

    Science.gov (United States)

    Murphy, B E; Krasnikov, S A; Cafolla, A A; Sergeeva, N N; Vinogradov, N A; Beggan, J P; Lübben, O; Senge, M O; Shvets, I V

    2012-02-01

    The room temperature self-assembly and ordering of (5,15-diphenylporphyrinato)nickel(II) (NiDPP) on the Ag(111) and Ag/Si(111)-(√3 × √3)R30° surfaces have been investigated using scanning tunnelling microscopy and low-energy electron diffraction. The self-assembled structures and lattice parameters of the NiDPP monolayer are shown to be extremely dependent on the reactivity of the substrate, and probable molecular binding sites are proposed. The NiDPP overlayer on Ag(111) grows from the substrate step edges, which results in a single-domain structure. This close-packed structure has an oblique unit cell and consists of molecular rows. The molecules in adjacent rows are rotated by approximately 17° with respect to each other. In turn, the NiDPP molecules form three equivalent domains on the Ag/Si(111)-(√3 × √3)R30° surface, which follow the three-fold symmetry of the substrate. The molecules adopt one of three equivalent orientations on the surface, acting as nucleation sites for these domains, due to the stronger molecule-substrate interaction compared to the case of the Ag(111). The results are explained in terms of the substrate reactivity and the lattice mismatch between the substrate and the molecular overlayer. PMID:22223550

  14. Interface dipoles of organic molecules on Ag(111) in hybrid density-functional theory

    Science.gov (United States)

    Hofmann, Oliver T.; Atalla, Viktor; Moll, Nikolaj; Rinke, Patrick; Scheffler, Matthias

    2013-12-01

    We investigate the molecular acceptors 3,4,9,10-perylene-tetracarboxylic acid dianhydride (PTCDA), 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) and 4,5,9,10-pyrenetetraone (PYTON) on Ag(111) using density-functional theory (DFT). For two groups of the Heyd-Scuseria-Ernzerhof (HSE(α, ω)) family of exchange-correlation functionals (ω = 0 and 0.2 Å) we study the isolated components as well as the combined systems as a function of the amount of exact-exchange (α). We find that hybrid functionals favour electron transfer to the adsorbate. Comparing with experimental work function data, for α ≈ 0.25 we report a notable but small improvement over (semi) local functionals for the interface dipole. Although Kohn-Sham eigenvalues are only approximate representations of ionization energies, incidentally, at this value also the density of states agrees well with the photoelectron spectra. However, increasing α to values for which the energy of the lowest unoccupied molecular orbital matches the experimental electron affinity in the gas phase worsens both the interface dipole and the density of states. Our results imply that semi-local DFT calculations may often be adequate for conjugated organic molecules on metal surfaces and that the much more computationally demanding hybrid functionals yield only small improvements.

  15. Self-Assembly of Tetraphenyldibenzoperiflanthene (DBP) Films on Ag(111) in the Monolayer Regime.

    Science.gov (United States)

    Kirchhuebel, Tino; Gruenewald, Marco; Sojka, Falko; Kera, Satoshi; Bussolotti, Fabio; Ueba, Takahiro; Ueno, Nobuo; Rouillé, Gaël; Forker, Roman; Fritz, Torsten

    2016-03-01

    Tetraphenyldibenzoperiflanthene (DBP) is a promising candidate as a component of highly efficient organic photovoltaic cells and organic light-emitting diodes. The structural properties of thin films of this particular lander-type molecule on Ag(111) were investigated by complementary techniques. Highly ordered structures were obtained, and their mutual alignment was characterized by means of low-energy electron diffraction (LEED). Scanning tunneling microscopy (STM) images reveal two slightly different arrangements within the first monolayer (ML), both describable as specific herringbone patterns with two molecules per unit cell whose dibenzoperiflanthene framework is parallel to the surface. In contrast, single DBP molecules in the second ML were imaged with much higher intramolecular resolution, resembling the shape of the frontier orbitals in the gas phase as calculated by means of density functional theory (DFT). Further deposition leads to the growth of highly ordered bilayer islands on top of the first ML with identical unit cell dimensions and orientation but slightly inclined molecules. This suggests that the first ML acts as a template for the epitaxial growth of further layers. Simultaneously, a significant number of second-layer molecules mainly located at step edges or scattered over narrow terraces do not form highly ordered aggregates. PMID:26844381

  16. Quasi-freestanding epitaxial silicene on Ag(111) by oxygen intercalation.

    Science.gov (United States)

    Du, Yi; Zhuang, Jincheng; Wang, Jiaou; Li, Zhi; Liu, Hongsheng; Zhao, Jijun; Xu, Xun; Feng, Haifeng; Chen, Lan; Wu, Kehui; Wang, Xiaolin; Dou, Shi Xue

    2016-07-01

    Silicene is a monolayer allotrope of silicon atoms arranged in a honeycomb structure with massless Dirac fermion characteristics similar to graphene. It merits development of silicon-based multifunctional nanoelectronic and spintronic devices operated at room temperature because of strong spin-orbit coupling. Nevertheless, until now, silicene could only be epitaxially grown on conductive substrates. The strong silicene-substrate interaction may depress its superior electronic properties. We report a quasi-freestanding silicene layer that has been successfully obtained through oxidization of bilayer silicene on the Ag(111) surface. The oxygen atoms intercalate into the underlayer of silicene, resulting in isolation of the top layer of silicene from the substrate. In consequence, the top layer of silicene exhibits the signature of a 1 × 1 honeycomb lattice and hosts massless Dirac fermions because of much less interaction with the substrate. Furthermore, the oxidized silicon buffer layer is expected to serve as an ideal dielectric layer for electric gating in electronic devices. These findings are relevant for the future design and application of silicene-based nanoelectronic and spintronic devices. PMID:27532041

  17. Interface dipoles of organic molecules on Ag(111) in hybrid density-functional theory

    International Nuclear Information System (INIS)

    We investigate the molecular acceptors 3,4,9,10-perylene-tetracarboxylic acid dianhydride (PTCDA), 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) and 4,5,9,10-pyrenetetraone (PYTON) on Ag(111) using density-functional theory (DFT). For two groups of the Heyd–Scuseria–Ernzerhof (HSE(α, ω)) family of exchange-correlation functionals (ω = 0 and 0.2 Å) we study the isolated components as well as the combined systems as a function of the amount of exact-exchange (α). We find that hybrid functionals favour electron transfer to the adsorbate. Comparing with experimental work function data, for α ≈ 0.25 we report a notable but small improvement over (semi) local functionals for the interface dipole. Although Kohn–Sham eigenvalues are only approximate representations of ionization energies, incidentally, at this value also the density of states agrees well with the photoelectron spectra. However, increasing α to values for which the energy of the lowest unoccupied molecular orbital matches the experimental electron affinity in the gas phase worsens both the interface dipole and the density of states. Our results imply that semi-local DFT calculations may often be adequate for conjugated organic molecules on metal surfaces and that the much more computationally demanding hybrid functionals yield only small improvements. (paper)

  18. High resolution photoelectron spectroscopy at the SnPc/Ag(111) interface

    Energy Technology Data Exchange (ETDEWEB)

    Scheuermann, C.; Haeming, M.; Kroeger, I.; Stadler, C.; Kumpf, C.; Schoell, A.; Reinert, F.; Umbach, E. [Universitaet Wuerzburg, Experimentelle Physik II, 97074 Wuerzburg (Germany)

    2008-07-01

    Phthalocyanines are interesting for applications in organic devices due to the potential of tailoring their properties by introducing different metal ligands into the heterocycle. Some derivates offer the potential of tuning the work function of metal contacts due to an intrinsic dipole moment. We present a high resolution photoelectron spectroscopy study on SnPc submonolayers on Ag(111). Based on a structural analysis, which shows the existence of different adsorption phases with different orientation of the molecular dipoles depending on temperature and coverage, the PES data indicate a significant effect on the surface work function. The valence and core spectra allow identifying a covalent interaction at the interface with the appearance of a new state at EF. Moreover, the data provide evidence for a systematic weakening of the interfacial interaction with increasing coverage. This is accompanied by a constriction of the substrate-adsorbate charge transfer, which becomes evident from an analysis of the core level line shapes. As a consequence, a comprehensive description of the electronic structure in the contact regime, of the resulting interface dipole, and of work function effects needs to account not only for structural properties such as the intrinsic molecular geometry, but also for intermolecular- and interfacial interactions which may involve significant charge transfer.

  19. Structural and electronic properties of thin organic heterointerfaces SnPc/PTCDA/Ag(111)

    Energy Technology Data Exchange (ETDEWEB)

    Haeming, Mark; Sauer, Christoph; Greif, Michael; Schoell, Achim [Universitaet Wuerzburg, Experimentelle Physik VII, Wuerzburg (Germany); Reinert, Friedrich [Universitaet Wuerzburg, Experimentelle Physik VII, Wuerzburg (Germany); KIT, Gemeinschaftslabor fuer Nanoanalytik, Karlsruhe (Germany)

    2011-07-01

    Knowledge about the structural and electronic properties of organic heterointerfaces is of vital importance for electronic devices based on organic semiconductors. Yet information about these systems is still scarce due to difficulties in preparing well defined interfaces. With tin-phtalocyanine (SnPc) deposited on a Ag(111) surface precovered by perylene-tetracarboxylic acid dianhydride (PTCDA) we present a well suited model system to gain insight into such heterointerfaces. Photoelectron spectroscopy (XPS and UPS) as well as near edge X-ray absorption fine structure (NEXAFS) studies are applied in order to gain both structural and electronic information. Distinct features in core-level and valence spectra allow us to unambiguously distinguish between both molecules. We show clear evidence that SnPc forms a flat lying wetting layer on top of PTCDA with a mainly physisorptive character. Moreover a rigid level shift of all spectroscopic SnPc features with respect to the homomolecular SnPc films is observed, similar to what is known for Schottky contacts, which corresponds to a change in work function. We demonstrate that the built-in electric field at the interface can be explained by the formation of an interface dipole, which extends over several adsorbate monolayers.

  20. Substrate dependent bonding distances of PTCDA - A comparative XSW study on Cu(111) and Ag(111)

    OpenAIRE

    Gerlach, A; Sellner, S.; Schreiber, F.; Koch, N; Zegenhagen, J.

    2006-01-01

    We study the adsorption geometry of 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA) on Ag(111) and Cu(111) using X-ray standing waves. The element-specific analysis shows that the carbon core of the molecule adsorbs in a planar configuration, whereas the oxygen atoms experience a non-trivial and substrate dependent distortion. On copper (silver) the carbon rings resides 2.66 A (2.86 A) above the substrate. In contrast to the conformation on Ag(111), where the carboxylic oxygen atoms are...

  1. Conductance of Ag atoms and clusters on Ag(111): Spectroscopic and time-resolved data

    Energy Technology Data Exchange (ETDEWEB)

    Sperl, A.; Kroeger, J.; Berndt, R. [Institut fuer Experimentelle und Angewandte Physik, Christian-Albrechts-Universitaet zu Kiel (Germany)

    2010-05-15

    The evolution of the electronic structure of linear atomic Ag chains on Ag(111) has been explored atom by atom using low-temperature scanning tunnelling microscopy and spectroscopy. Electronic states confined to the linear chains are well described within a particle-in-a-box model. The evolution of an unoccupied Ag monomer resonance during the synthesis of an Ag dimer reveals that the Ag-Ag interaction is predominantly direct owing to the large spatial extension of p wave functions of the adsorbed atoms. The hopping dynamics of a single Ag atom adsorbed on Ag(111) have been monitored by time-resolved two-level conductance fluctuations of the tunnel junctions. Effective temperatures of the junction and diffusion barrier heights in the presence of the tip were extracted from a voltage-dependent analysis of the fluctuation rate. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  2. A three-dimensional self-learning kinetic Monte Carlo model: application to Ag(111)

    International Nuclear Information System (INIS)

    The reliability of kinetic Monte Carlo (KMC) simulations depends on accurate transition rates. The self-learning KMC method (Trushin et al 2005 Phys. Rev. B 72 115401) combines the accuracy of rates calculated from a realistic potential with the efficiency of a rate catalog, using a pattern recognition scheme. This work expands the original two-dimensional method to three dimensions. The concomitant huge increase in the number of rate calculations on the fly needed can be avoided by setting up an initial database, containing exact activation energies calculated for processes gathered from a simpler KMC model. To provide two representative examples, the model is applied to the diffusion of Ag monolayer islands on Ag(111), and the homoepitaxial growth of Ag on Ag(111) at low temperatures.

  3. Two-photon Photo-emission of Ultrathin Film PTCDA Morphologies on Ag(111)

    OpenAIRE

    Yang, Aram

    2008-01-01

    Morphology- and layer-dependent electronic structure and dynamics at the PTCDA/Ag(111) interface have been studied with angle-resolved two-photon photoemission. In Stranski-Krastanov growth modes, the exposed wetting layer inhibited the evolution of the vacuum level and valence band to bulk values. For layer-by-layer growth, we observed the transition of electron structure from monolayer to bulk values within eight monolayers. Effective masses and lifetimes of the conduction band and the n=1 ...

  4. Untersuchung der Elektronendynamik an der PTCDA/Ag(111)-Grenzfläche

    OpenAIRE

    Schwalb, Christian

    2009-01-01

    Im Rahmen dieser Arbeit wird die Elektronendynamik an der PTCDA/Ag(111)-Grenzfläche mit Hilfe von zeit- und winkelaufgelöster Zweiphotonen-Photoemission (2PPE) sowie zeitaufgelöster Photolumineszenz-Spektroskopie (PL) untersucht. Der erste Teil der Arbeit widmet sich der Charakterisierung eines unbesetzten elektronischen Zustands, der sich durch die Adsorption der PTCDA-Moleküle 0.6 eV oberhalb der Fermienergie ausbildet, während ...

  5. Normal-incidence x-ray standing-wave determination of the adsorption geometry of PTCDA on Ag(111): Comparison of the ordered room-temperature and disordered low-temperature phases

    OpenAIRE

    Hauschild, A.; Temirov, R.; Soubatch, S.; Bauer, O.; Schöll, A.; Cowie, B.C.C.; Lee, T. -L.; Tautz, F. S.; Sokolowski, M.

    2010-01-01

    Normal incidence x-ray standing wave (NIXSW) experiments have been performed for monolayers of 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA) adsorbed on the Ag(111) surface. Two phases were analyzed: the low-temperature phase (LT phase), which is disordered and obtained for deposition at substrate temperatures below 150 K, and the ordered phase, which is obtained for deposition at room temperature (RT phase). From the NIXSW analysis the vertical bonding distances to the Ag surface wer...

  6. Surface modification of fluorocarbon polymers by synchrotron radiation

    CERN Document Server

    Kanda, K; Matsui, S; Ideta, T; Ishigaki, H

    2003-01-01

    The surface modification of a poly (tetrafluoroethylene) sheet was carried out by synchrotron radiation in the soft X-ray region. The poly (tetrafluoroethylene) substrate was exposed to synchrotron radiation while varying the substrate temperature from room temperature to 200degC. The contact angle of the modified surfaces with a water drop decreased from 96deg to 72deg by the irradiation at room temperature, while the contact angle increased to 143deg by the irradiation at the substrate temperature of 200degC. Scanning electron microscopy suggested that this repellence was ascribable to the microstructure of the poly (tetrafluoroethylene) surface. We succeeded in controlling the wettability of the poly (tetrafluoroethylene) surface from hydrophobic to hydrophilic by irradiation of the soft X-ray light. (author)

  7. THE ORGANIC LED SURFACE: A SYNCHROTRON RADIATION PHOTOEMISSION STUDY

    OpenAIRE

    TUN-WEN PI; T. C. YU

    2007-01-01

    Tris(8-hydroxyquinolato) aluminum (Alq3), a prototypical molecule for organic light-emitting devices, has been studied via synchrotron radiation photoemission to investigate (1) the surface electronic structure of the molecules at room temperature and at elevated temperatures, (2) adsorption onto the inorganic Si(001)-2×1 surface, and (3) doping with the alkaline metal Mg. For case (1), three chemical environments of carbon are resolved. Moreover, the shake-up satellite structures are detecte...

  8. Site-specific dissociation dynamics of H2/D2 on Ag(111) and Co(0001) and the validity of the site-averaging model

    International Nuclear Information System (INIS)

    Dissociative chemisorption of polyatomic molecules on metal surfaces involves high-dimensional dynamics, of which quantum mechanical treatments are computationally challenging. A promising reduced-dimensional approach approximates the full-dimensional dynamics by a weighted average of fixed-site results. To examine the performance of this site-averaging model, we investigate two distinct reactions, namely, hydrogen dissociation on Co(0001) and Ag(111), using accurate first principles potential energy surfaces (PESs). The former has a very low barrier of ∼0.05 eV while the latter is highly activated with a barrier of ∼1.15 eV. These two systems allow the investigation of not only site-specific dynamical behaviors but also the validity of the site-averaging model. It is found that the reactivity is not only controlled by the barrier height but also by the topography of the PES. Moreover, the agreement between the site-averaged and full-dimensional results is much better on Ag(111), though quantitative in neither system. Further quasi-classical trajectory calculations showed that the deviations can be attributed to dynamical steering effects, which are present in both reactions at all energies

  9. The adsorption geometry of PTCDA on Ag(111). An NIXSW study

    Energy Technology Data Exchange (ETDEWEB)

    Hauschild, Annegret

    2007-12-14

    The bonding lengths of a large pi-conjugated molecule which was adsorbed on a metal surface were determined for the first molecular layer. The system consisting of the organic molecules 3,4,9,10-Perylenetetracarboxylic dianhydride (PTCDA) grown on a silver(111) surface was investigated. PTCDA on Ag(111) appears in two phases in the first layer: The commensurate long range ordered monolayer at room temperature (RT phase) is a stable phase, whereas the disordered phase which is grown at temperatures below 160 K (LT phase) is a metastable phase. The bonding distance of the molecules from the surface is an indication for the bonding strength. Distortions of the molecules from the planar geometry give additional information on the bonding mechanism. Using NIXSW, the vertical distance of the molecules was investigated by the core-level C1s transition. Since carbon is the main element of the molecules, its vertical distance corresponds to the averaged molecular distance. Furthermore, the distances of the oxygen atoms of the molecules were determined by using the O1s transition. In the molecule, two types of chemically different oxygen atoms exist: the four outer carboxylic oxygen atoms and the two inner anhydride oxygen atoms. For the first time, this chemical shift of one atom sort within a molecule was utilized for a separation of the photoemission spectra which were taken in a standing wave experiment. Within this work, different vertical positions for atoms of the same element could be identified. For the RT phase an average molecular bonding distance of 2.86 A was measured. For the LT phase the corresponding value is 2.80 A. Thus, the molecules in the LT phase are 0.06 A closer to the Ag surface than the molecules in the RT phase, this result clearly is significant. In the LT phase, a stronger intramolecular distortion was observed, the oxygen atoms lie 0.14 A below the carbon core, whereas the molecules in the RT phase do not exhibit such a strong distortion, the

  10. Late growth stages and post-growth diffusion in organic epitaxy: PTCDA on Ag(111)

    OpenAIRE

    Krause, B.; Duerr, A. C.; Schreiber, F.; Dosch, H.; Seeck, O.H.

    2004-01-01

    The late growth stages and the post-growth diffusion of crystalline organic thin films have been investigated for 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) on Ag(111), a model system in organic epitaxy. In situ x-ray measurements at the anti-Bragg point during the growth show intensity oscillations followed by a time-independent intensity which is independent of the growth temperature. At T > 350 K, the intensity increases after growth up to a temperature-dependent saturation value...

  11. Growth and structure of the organic molecule PTCDA on Ag(111)

    OpenAIRE

    Krause, Bärbel

    2002-01-01

    Thin 3,4,9,10-perylene-tetracarboxylic dianhydride (PTCDA) films with the average thickness d between 50 and 200 Å, and the deposition rate F between 1 and 10 Å/min, have been deposited by molecular beam epitaxy on Ag(111). The films have been studied by atomic force microscopy and X-ray diffraction. It has been found that their structural and morphological properties vary significantly with the growth conditions. A transition from relatively smooth films to island growth on top of 2 wetting...

  12. Manipulation resolves non-trivial structure of corrole monolayer on Ag(111).

    Science.gov (United States)

    Tebi, Stefano; Aldahhak, Hazem; Serrano, Giulia; Schöfberger, Wolfgang; Rauls, Eva; Schmidt, Wolf Gero; Koch, Reinhold; Müllegger, Stefan

    2016-01-15

    Non-trivial arrangement of molecules within a molecular network complicates structure determination due to interdigitation, partial overlap, or stacking. We demonstrate that combined imaging and lateral manipulation with a scanning tunneling microscope resolves the intricate structure of a molecular network in two-dimensions in a straightforward manner. The network, formed by a monolayer of 5,10,15-tris(pentafluorophenyl)-corrole molecules on Ag(111), is manipulated for the first time with single-molecule precision. Our results reveal a shingle-like packing of partially overlapping corrole molecules. Density functional theory calculations support our findings. PMID:26629708

  13. Atomic structure of Ag(111) saturated with chlorine: Formation of Ag3Cl7 clusters

    Science.gov (United States)

    Andryushechkin, B. V.; Cherkez, V. V.; Gladchenko, E. V.; Zhidomirov, G. M.; Kierren, B.; Fagot-Revurat, Y.; Malterre, D.; Eltsov, K. N.

    2011-08-01

    The structure of saturated chlorine layer on Ag(111) has been studied with low temperature scanning tunneling microscopy and density functional theory. For the first time atomic-resolution STM images of saturated chlorine coverage have been obtained. STM images demonstrate coexistence of the domain with (3 × 3)-like reconstruction and numerous bright objects identified as Ag3Cl7 clusters. According to our model supported by DFT calculations, clusters are formed on the boundaries between the adjacent (3×3) antiphase domains. These boundaries have a characteristic triangular shape and are formed by six chlorine atoms chemisorbed on the triangular silver island with local periodicity (1 × 1).

  14. Electronic structure at the perylene-tetracarboxylic acid dianhydride/Ag(111) interface studied with two-photon photoelectron spectroscopy.

    Science.gov (United States)

    Sachs, Sönke; Schwalb, Christian H; Marks, Manuel; Schöll, Achim; Reinert, Friedrich; Umbach, Eberhard; Höfer, Ulrich

    2009-10-14

    The electronic structure of the prototype metal/organic contact 3,4,9,10-perylene-tetracarboxylic acid dianhydride (PTCDA) on a Ag(111)-surface has been investigated using time- and angle-resolved two-photon photoelectron spectroscopy (2PPE). Our analysis addresses particularly the nature of the interface state (IS) emerging at the interface due to the substrate-adsorbate interaction [C. H. Schwalb, S. Sachs, M. Marks et al., Phys. Rev. Lett. 101, 146801 (2008)]. Its free-electron-like dispersion and a possible backfolding at the surface Brillouin zone boundaries are discussed. Time-resolved pump-probe experiments reveal the inelastic electron lifetime along the dispersion parabola and show its decrease for increasing parallel momentum. The temperature dependence of the peak linewidth indicates a coupling of the IS to molecular vibrations. Moreover, additional aspects are addressed, such as the determination of the electron attenuation length of photoelectrons for low kinetic energy originating from the IS and the work function change of the sample upon PTCDA adsorption with very high energy resolution. PMID:19831458

  15. Surface, interface and bulk materials characterization using Indus synchrotron sources

    International Nuclear Information System (INIS)

    Synchrotron radiation sources, providing intense, polarized and stable beams of ultra violet, soft and hard x-ray photons, are having great impact on physics, chemistry, biology, materials science and other areas research. In particular synchrotron radiation has revolutionized materials characterization techniques by enhancing its capabilities for investigating the structural, electronic and magnetic properties of solids. The availability of synchrotron sources and necessary instrumentation has led to considerable improvements in spectral resolution and intensities. As a result, application scope of different materials characterization techniques has tremendously increased particularly in the analysis of solid surfaces, interfaces and bulk materials. The Indian synchrotron storage ring, Indus-1 and Indus-2 are in operation at RRCAT, Indore. The UGC-DAE CSR with the help of university scientist had designed and developed an angle integrated photoelectron spectroscopy (AlPES) beam line on Indus-1 storage ring of 450 MeV and polarized light beam line for soft x-ray absorption spectroscopy (SXAS) on Indus-2 storage ring of 2.5 GeV. (author)

  16. 3D-force-spectroscopy and -dissipation data of an organic-inorganic interface: PTCDA on Ag(111)

    Energy Technology Data Exchange (ETDEWEB)

    Braun, Daniel-Alexander; Langewisch, Gernot; Fuchs, Harald; Schirmeisen, Andre [CeNTech (Center for Nanotechnology) and Institute of Physics, University of Muenster (Germany)

    2009-07-01

    Organic semiconductors have attracted intensive research over the last years. Especially the adsorption of {pi}-conjugated organic molecules on metal substrates in view of potential applications in organic and molecular electronics gained a lot of interest. One of the most studied molecules is 3,4,9,10-perylenetetracarboxylic-dianhydride (PTCDA) and it has been investigated on a wide range of substrates. Noncontact atomic force microscopy (ncAFM) experiments with PTCDA adsorbed on Cu(111) revealed, that the intramolecular contrast of PTCDA-molecules depends strongly on the local adsorption environment. Here we present experimental ncAFM results of 3-dimensional force and dissipation spectroscopy experiments of PTCDA adsorbed on Ag(111) with submolecular resolution. The dissipation is understood as a hysteresis of forces between approach and retraction of the tip and is caused by bistabilities in the potential energy surface of the tip-sample system. Therefore the dissipation signal can reveal information about the mechanical properties of individual molecules.

  17. Dynamics of electron transport at the PTCDA/Ag(111)-interface studied with time-resolved 2PPE

    Energy Technology Data Exchange (ETDEWEB)

    Schwalb, Christian; Marks, Manuel B.; Hoefer, Ulrich [Fachbereich Physik, Zentrum fuer Materialwissenschaften, Philipps-Universitaet Marburg, D-35032 Marburg (Germany); Sachs, Soenke; Schoell, Achim [Universitaet Wuerzburg, Experimentelle Physik II, D-97074 Wuerzburg (Germany); Umbach, Eberhard [Universitaet Wuerzburg, Experimentelle Physik II, D-97074 Wuerzburg (Germany); Forschungszentrum Karlsruhe, D-76021 Karlsruhe (Germany)

    2009-07-01

    Time-resolved two-photon photoemission (2PPE) is able to provide very detailed information about the electronic structure and the dynamics of electron transfer processes of well-ordered interfaces between organic semiconductors and metals. As a model system we have investigated thin epitaxial PTCDA films on Ag(111). A dispersing unoccupied state with an effective electron mass of 0.39 m{sub e} at the anti {gamma}-point emerges 0.6 eV above the metallic Fermi level E{sub F}. Its short lifetime of 55 fs is a clear indication that this state has a strong overlap with the metal and essentially originates from an upshift of the Shockley surface state of the Ag substrate. In order to investigate the role of the interface state for charge carrier injection, we populate the LUMO of PTCDA in films of varying thickness and simultaneously record fluorescence and photoemission spectra. A long lived component observed in the 2PPE signal close to E{sub F} clearly correlates with film thickness and fluorescence lifetime.

  18. The fate of the 2√3 × 2√3R(30°) silicene phase on Ag(111)

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Zhi-Long; Wang, Mei-Xiao; Liu, Canhua, E-mail: canhualiu@sjtu.edu.cn, E-mail: depadova@ism.cnr.it, E-mail: guy.lelay@univ-amu.fr; Jia, Jin-Feng [Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093 (China); Vogt, Patrick [Technische Universität Berlin, Institut für Festkörperphysik, Hardenbergstraße 36, 10623 Berlin (Germany); Quaresima, Claudio; Ottaviani, Carlo; De Padova, Paola, E-mail: canhualiu@sjtu.edu.cn, E-mail: depadova@ism.cnr.it, E-mail: guy.lelay@univ-amu.fr [CNR-ISM, via Fosso del Cavaliere, Rome 00133 (Italy); Olivieri, Bruno [ISAC-CNR, via Fosso del Cavaliere 100, Rome (Italy); Lay, Guy Le, E-mail: canhualiu@sjtu.edu.cn, E-mail: depadova@ism.cnr.it, E-mail: guy.lelay@univ-amu.fr [Aix-Marseille Université, CNRS, PIIM UMR 7345, 13397, Marseille (France)

    2014-09-01

    Silicon atoms deposited on Ag(111) produce various single layer silicene sheets with different buckling patterns and periodicities. Low temperature scanning tunneling microscopy reveals that one of the silicene sheets, the hypothetical √7 × √7 silicene structure, on 2√3 × 2√3 Ag(111), is inherently highly defective and displays no long-range order. Moreover, Auger and photoelectron spectroscopy measurements reveal its sudden death, to end, in a dynamic fating process at ∼300 °C. This result clarifies the real nature of the 2√3 × 2√3R(30°) silicene phase and thus helps to understand the diversity of the silicene sheets grown on Ag(111)

  19. Structure and stability of acrolein and allyl alcohol networks on Ag(111) from density functional theory based calculations with dispersion corrections

    Science.gov (United States)

    Ferullo, Ricardo M.; Branda, Maria Marta; Illas, Francesc

    2013-11-01

    The interaction of acrolein and allyl alcohol with the Ag(111) surface has been studied by means of periodic density functional theory based calculations including explicitly dispersion terms. Different coverage values have been explored going from isolated adsorbed molecules to isolated dimers, interacting dimers or ordered overlayers. The inclusion of the dispersion terms largely affects the calculated values of the adsorption energy and also the distance between adsorbed molecule and the metallic surface but much less the adsorbate-adsorbate interactions. Owing to the large dipole moment of acrolein, the present calculations predict that at high coverage this molecule forms a stable extensive two-dimensional network on the surface, caused by the alignment of the adsorbate dipoles. For the case of allyl alcohol, dimers and complex networks exhibit similar stability.

  20. Vermessung von Dispersion und Elektronendynamik der NTCDA/Ag(111) Grenzflächenzustände mittels 2-Photonen-Photoemission

    OpenAIRE

    Schmidt, Benjamin

    2010-01-01

    Vermessung der Bildpotentialzustände sowie des Interfacezustands an der NTCDA/Ag(111)-Grenzfläche im Vergleich zum wohlbekannten PTCDA/Ag(111)-Modellsystem. Untersucht werden sowohl die Dispersion als auch die Elektronendynamik der Zustände.

  1. Influence of the adsorption geometry of PTCDA on Ag(111) on the tip-molecule forces in non-contact atomic force microscopy.

    Science.gov (United States)

    Langewisch, Gernot; Falter, Jens; Schirmeisen, André; Fuchs, Harald

    2014-01-01

    Perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) adsorbed on a metal surface is a prototypical organic-anorganic interface. In the past, scanning tunneling microscopy and scanning tunneling spectroscopy studies of PTCDA adsorbed on Ag(111) have revealed differences in the electronic structure of the molecules depending on their adsorption geometry. In the work presented here, high-resolution 3D force spectroscopy measurements at cryogenic temperatures were performed on a surface area that contained a complete PTCDA unit cell with the two possible geometries. At small tip-molecule separations, deviations in the tip-sample forces were found between the two molecule orientations. These deviations can be explained by a different electron density in both cases. This result demonstrates the capability of 3D force spectroscopy to detect even small effects in the electronic properties of organic adsorbates. PMID:24611130

  2. Influence of the adsorption geometry of PTCDA on Ag(111 on the tip–molecule forces in non-contact atomic force microscopy

    Directory of Open Access Journals (Sweden)

    Gernot Langewisch

    2014-01-01

    Full Text Available Perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA adsorbed on a metal surface is a prototypical organic–anorganic interface. In the past, scanning tunneling microscopy and scanning tunneling spectroscopy studies of PTCDA adsorbed on Ag(111 have revealed differences in the electronic structure of the molecules depending on their adsorption geometry. In the work presented here, high-resolution 3D force spectroscopy measurements at cryogenic temperatures were performed on a surface area that contained a complete PTCDA unit cell with the two possible geometries. At small tip-molecule separations, deviations in the tip-sample forces were found between the two molecule orientations. These deviations can be explained by a different electron density in both cases. This result demonstrates the capability of 3D force spectroscopy to detect even small effects in the electronic properties of organic adsorbates.

  3. Influence of the adsorption geometry of PTCDA on Ag(111) on the tip–molecule forces in non-contact atomic force microscopy

    Science.gov (United States)

    Langewisch, Gernot; Falter, Jens; Fuchs, Harald

    2014-01-01

    Summary Perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) adsorbed on a metal surface is a prototypical organic–anorganic interface. In the past, scanning tunneling microscopy and scanning tunneling spectroscopy studies of PTCDA adsorbed on Ag(111) have revealed differences in the electronic structure of the molecules depending on their adsorption geometry. In the work presented here, high-resolution 3D force spectroscopy measurements at cryogenic temperatures were performed on a surface area that contained a complete PTCDA unit cell with the two possible geometries. At small tip-molecule separations, deviations in the tip-sample forces were found between the two molecule orientations. These deviations can be explained by a different electron density in both cases. This result demonstrates the capability of 3D force spectroscopy to detect even small effects in the electronic properties of organic adsorbates. PMID:24611130

  4. Glass transition near the free surface studied by synchrotron radiation

    International Nuclear Information System (INIS)

    A comprehensive picture of the glass transition near the liquid/vapor interface of the model organic glass former dibutyl phthalate is presented in this work. Several surface-sensitive techniques using x-ray synchrotron radiation were applied to investigate the static and dynamic aspects of the formation of the glassy state from the supercooled liquid. The amorphous nature of dibutyl phthalate close to the free surface was confirmed by grazing incidence X-ray diffraction studies. Results from X-ray reflectivity measurements indicate a uniform electron density distribution close to the interface excluding the possibility of surface freezing down to 175 K. Dynamics on sub-μm length-scales at the surface was studied with coherent synchrotron radiation via x-ray photon correlation spectroscopy. From the analysis of the dispersion relation of the surface modes, viscoelastic properties of the dibutyl phthalate are deduced. The Kelvin-Voigt model of viscoelastic media was found to describe well the properties of the liquid/vapor interface below room temperature. The data show that the viscosity at the interface matches the values reported for bulk dibutyl phthalate. The scaled relaxation rate at the surface agrees with the bulk data above 210 K. Upon approaching the glass transition temperature the free surface was observed to relax considerably faster close to the liquid/vapor interface than in bulk. The concept of higher relaxation rate at the free surface is also supported by the results of the quasielastic nuclear forward scattering experiment, during which dynamics on molecular length scales around the calorimetric glass transition temperature is studied. The data were analyzed using mode-coupling theory of the glass transition and the model of the liquid(glass)/vapor interface, predicting inhomogeneous dynamics near the surface. The quasielastic nuclear forward scattering data can be explained when the molecular mobility is assumed to decrease with the increasing

  5. Glass transition near the free surface studied by synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Sikorski, M.

    2008-06-15

    A comprehensive picture of the glass transition near the liquid/vapor interface of the model organic glass former dibutyl phthalate is presented in this work. Several surface-sensitive techniques using x-ray synchrotron radiation were applied to investigate the static and dynamic aspects of the formation of the glassy state from the supercooled liquid. The amorphous nature of dibutyl phthalate close to the free surface was confirmed by grazing incidence X-ray diffraction studies. Results from X-ray reflectivity measurements indicate a uniform electron density distribution close to the interface excluding the possibility of surface freezing down to 175 K. Dynamics on sub-{mu}m length-scales at the surface was studied with coherent synchrotron radiation via x-ray photon correlation spectroscopy. From the analysis of the dispersion relation of the surface modes, viscoelastic properties of the dibutyl phthalate are deduced. The Kelvin-Voigt model of viscoelastic media was found to describe well the properties of the liquid/vapor interface below room temperature. The data show that the viscosity at the interface matches the values reported for bulk dibutyl phthalate. The scaled relaxation rate at the surface agrees with the bulk data above 210 K. Upon approaching the glass transition temperature the free surface was observed to relax considerably faster close to the liquid/vapor interface than in bulk. The concept of higher relaxation rate at the free surface is also supported by the results of the quasielastic nuclear forward scattering experiment, during which dynamics on molecular length scales around the calorimetric glass transition temperature is studied. The data were analyzed using mode-coupling theory of the glass transition and the model of the liquid(glass)/vapor interface, predicting inhomogeneous dynamics near the surface. The quasielastic nuclear forward scattering data can be explained when the molecular mobility is assumed to decrease with the increasing

  6. Dynamics of Spatially Confined Bisphenol A Trimers in a Unimolecular Network on Ag(111).

    Science.gov (United States)

    Lloyd, Julian A; Papageorgiou, Anthoula C; Fischer, Sybille; Oh, Seung Cheol; Saǧlam, Özge; Diller, Katharina; Duncan, David A; Allegretti, Francesco; Klappenberger, Florian; Stöhr, Martin; Maurer, Reinhard J; Reuter, Karsten; Reichert, Joachim; Barth, Johannes V

    2016-03-01

    Bisphenol A (BPA) aggregates on Ag(111) shows a polymorphism between two supramolecular motifs leading to formation of distinct networks depending on thermal energy. With rising temperature a dimeric pairing scheme reversibly converts into a trimeric motif, which forms a hexagonal superstructure with complex dynamic characteristics. The trimeric arrangements notably organize spontaneously into a self-assembled one-component array with supramolecular BPA rotors embedded in a two-dimensional stator sublattice. By varying the temperature, the speed of the rotors can be controlled as monitored by direct visualization. A combination of scanning tunneling microscopy and dispersion-corrected density-functional tight-binding (DFTB-vdW(surf)) based molecular modeling reveals the exact atomistic position of each molecule within the assembly as well as the driving force for the formation of the supramolecular rotors. PMID:26849384

  7. Structure of chlorine on Ag(111): Evidence of the (3×3) reconstruction

    Science.gov (United States)

    Andryushechkin, B. V.; Cherkez, V. V.; Gladchenko, E. V.; Zhidomirov, G. M.; Kierren, B.; Fagot-Revurat, Y.; Malterre, D.; Eltsov, K. N.

    2010-05-01

    The structure of the chlorine induced reconstruction of Ag(111) has been studied by a combination of low-temperature scanning tunneling microscopy (STM), low-energy electron diffraction (LEED), and density-functional theory (DFT). We demonstrate that previously observed mysterious LEED pattern arises as a result of diffraction from a system of small (15-30Å) triangular antiphase domains with a new (3×3) superstructure. In our model supported by DFT calculations, within a (3×3) unit cell the upper silver layer reconstructs forming a couple of three-atom triangles placed in fcc and hcp sites of the substrate. Chlorine atoms occupy fourfold hollow sites between these triangles. The corner holes, which look like depressions in the STM images, are also occupied by chlorine atoms.

  8. Processes of adsorption/desorption of iodides and cadmium cations onto/from Ag(111

    Directory of Open Access Journals (Sweden)

    VLADIMIR D. JOVIĆ

    2011-02-01

    Full Text Available In this work, the adsorption/desorption processes of iodides and cadmium cations in the presence of iodides onto/from Ag(111 were investigated. It was shown that both processes were complex, characterized by several peaks on the cyclic voltammograms (CVs. By PeakFit analysis of the recorded CVs and subsequent fitting of the obtained peaks by the Frumkin adsorption isotherm, the interaction parameter (f and the Gibbs energy of adsorption (DGads for each adsorbed phase were determined. In the case of iodide adsorption, four peaks were characterized by negative values of f, indicating attractive lateral interaction between the adsorbed anions, while two of them possessed value of f < –4, indicating phase transition processes. The adsorption/desorption processes of cadmium cations (underpotential deposition – UPD of cadmium in the presence of iodide anions was characterized by two main peaks, each of them being composed of two or three peaks with negative values of f. By the analysis of charge vs. potential dependences obtained either from the CVs or current transients on potentiostatic pulses, it was concluded that adsorbed iodides did not undergo desorption during the process of Cd UPD, but became replaced by Cd ad-atoms and remained adsorbed on top of a Cd layer and/or in between Cd the ad-atoms.

  9. Complex Stoichiometry reordering of PTCDA on Ag(111) upon K Intercalation

    Science.gov (United States)

    Brivio, G. P.; Baby, A.; Zwick, C.; Gruenewald, M.; Forker, R.; Fritz, T.; Fratesi, G.; Hofmann, O. T.; Zojer, E.

    Alkali metal atoms are a simple yet efficient n-type dopant of organic semiconductors. However, the molecular crystal structures need be controlled and well understood in order to optimize the electronic properties (charge carrier density and mobility) of the target material. Here, we report that potassium intercalation into PTCDA monolayer domains on a Ag(111) substrate induces distinct stoichiometry-dependent structural reordering processes, resulting in highly ordered and large KxPTCDA domains. The emerging structures are analyzed by low temperature scanning tunneling microscopy (STM), scanning tunneling hydrogen microscopy (STHM), and low-energy electron diffraction (LEED) as a function of the stoichiometry and by density functional theory (DFT) calculations. Large stable monolayer domains are found for x=2,4. The epitaxy types for all intercalated stages are determined as point-on-line. The K atoms adsorb in the vicinity of the oxygen atoms of the PTCDA molecules, and their positions are determined with sub-Angstrom precision. This is a crucial prerequisite for the prospective assessment of the electronic properties of such composite films, as they depend on the mutual alignment between donor atoms and acceptor molecules.

  10. Adsorption of bay-substituted perylene bisimide dyes on Ag(111) investigated by PES and NEXAFS

    Energy Technology Data Exchange (ETDEWEB)

    Scholz, Markus; Krause, Stefan; Haeming, Marc; Schoell, Achim [Universitaet Wuerzburg (Germany). Experimentelle Physik II; Schmidt, Ruediger; Wuerthner, Frank [Universitaet Wuerzburg (Germany). Institut fuer Organische Chemie; Reinert, Friedrich [Universitaet Wuerzburg (Germany). Experimentelle Physik II; Gemeinschaftslabor fuer Nanoanalytik, Forschungszentrum Karlsruhe (Germany)

    2009-07-01

    Perylene tetracarboxylic acid bisimides (PBI) are among the best available n-conducting organic materials. Halogen substituents attached to the perylene bay positions change the molecular structure by introducing a twist angle into the usually planar perylene backbone. This influences the optical properties, the stacking of the molecules, as well as the electronic properties. Moreover, the molecular conformation is also expected to effect the interaction with metal contacts, an aspect of crucial importance for electronic devices. We report on a high resolution photoemission (PES) and x-ray absorption (NEXAFS) study of the electronic structure and the molecular orientation of ultra-thin films of the planer PBI-H{sub 4}, and the core twisted PBI-Cl{sub 4} on Ag(111) substrates. In the monolayer regime, substantial changes in the UPS and XPS data with respect to the bulk samples clearly indicate a covalent interaction at the interface. In the valence regime charge transfer induced occupied states are observed at the Fermi-level. This is corroborated by the NEXAFS results, which allow probing a possible change of the molecular conformation due to the interfacial interaction.

  11. Thermal stability and partial dewetting of crystalline organic thin films: 3,4,9,10-perylenetetracarboxylic dianhydride on Ag(111)

    OpenAIRE

    Krause, B.; Dürr, A. C.; Schreiber, F.; Dosch, H.; Seeck, O

    2003-01-01

    The thermal stability and dewetting effects of crystalline organic thin films on inorganic substrates have been investigated for a model system for organic epitaxy, 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) on Ag(111). The thin films deposited under a variety of growth conditions have been annealed stepwise and studied by in situ x-ray diffraction and noncontact atomic force microscopy. It has been found that comparatively smooth films deposited at temperatures T(g)less than or sim...

  12. Adsorption of the ionic liquid [BMP][TFSA] on Au(111 and Ag(111: substrate effects on the structure formation investigated by STM

    Directory of Open Access Journals (Sweden)

    Benedikt Uhl

    2013-12-01

    Full Text Available In order to resolve substrate effects on the adlayer structure and structure formation and on the substrate–adsorbate and adsorbate–adsorbate interactions, we investigated the adsorption of thin films of the ionic liquid (IL 1-butyl-1-methylpyrrolidinium-bis(trifluoromethylsulfonylimide [BMP][TFSA] on the close-packed Ag(111 and Au(111 surfaces by scanning tunneling microscopy, under ultra high vacuum (UHV conditions in the temperature range between about 100 K and 293 K. At room temperature, highly mobile 2D liquid adsorbate phases were observed on both surfaces. At low temperatures, around 100 K, different adsorbed IL phases were found to coexist on these surfaces, both on silver and gold: a long-range ordered (‘2D crystalline’ phase and a short-range ordered (‘2D glass’ phase. Both phases exhibit different characteristics on the two surfaces. On Au(111, the surface reconstruction plays a major role in the structure formation of the 2D crystalline phase. In combination with recent density functional theory calculations, the sub-molecularly resolved STM images allow to clearly discriminate between the [BMP]+ cation and [TFSA]− anion.

  13. Site-specific dissociation dynamics of H{sub 2}/D{sub 2} on Ag(111) and Co(0001) and the validity of the site-averaging model

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Xixi [Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131 (United States); Institute of Theoretical and Computational Chemistry, Key Laboratory of Mesoscopic Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China); Jiang, Bin [Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131 (United States); Department of Chemical Physics, University of Science and Technology of China, Hefei 230026 (China); Xie, Daiqian, E-mail: dqxie@nju.edu.cn, E-mail: hguo@unm.edu [Institute of Theoretical and Computational Chemistry, Key Laboratory of Mesoscopic Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China); Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Guo, Hua, E-mail: dqxie@nju.edu.cn, E-mail: hguo@unm.edu [Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131 (United States)

    2015-09-21

    Dissociative chemisorption of polyatomic molecules on metal surfaces involves high-dimensional dynamics, of which quantum mechanical treatments are computationally challenging. A promising reduced-dimensional approach approximates the full-dimensional dynamics by a weighted average of fixed-site results. To examine the performance of this site-averaging model, we investigate two distinct reactions, namely, hydrogen dissociation on Co(0001) and Ag(111), using accurate first principles potential energy surfaces (PESs). The former has a very low barrier of ∼0.05 eV while the latter is highly activated with a barrier of ∼1.15 eV. These two systems allow the investigation of not only site-specific dynamical behaviors but also the validity of the site-averaging model. It is found that the reactivity is not only controlled by the barrier height but also by the topography of the PES. Moreover, the agreement between the site-averaged and full-dimensional results is much better on Ag(111), though quantitative in neither system. Further quasi-classical trajectory calculations showed that the deviations can be attributed to dynamical steering effects, which are present in both reactions at all energies.

  14. Ambient pressure oxidation of Ag(111) surfaces : an in-situ X-ray study

    OpenAIRE

    Reicho, Alexander

    2008-01-01

    The oxidation of metals plays an outstanding role in everyday life. Typical phenomena are the formation of rust on steel or oxide scales on copper, showing up as a green patina. The formation of metal oxides is not always an unwanted process. The functionality of many materials is directly related to their controlled oxidation. The most prominent examples are passivating oxide layers on stainless steel. Relevant for this thesis are industrially applied heterogeneous catalytic reactions for th...

  15. Self-Diffusion of small Ag and Ni islands on Ag(111) and Ni(111) using the self-learning kinetic Monte Carlo method

    Science.gov (United States)

    Islamuddin Shah, Syed; Nandipati, Giridhar; Kara, Abdelkader; Rahman, Talat S.

    2012-02-01

    We have applied a modified Self-Learning Kinetic Monte Carlo (SLKMC) method [1] to examine the self-diffusion of small Ag and Ni islands, containing up to 10 atom, on the (111) surface of the respective metal. The pattern recognition scheme in this new SLKMC method allows occupancy of the fcc, hcp and top sites on the fcc(111) surface and employs them to identify the local neighborhood around a central atom. Molecular static calculations with semi empirical interatomic potential and reliable techniques for saddle point search revealed several new diffusion mechanisms that contribute to the diffusion of small islands. For comparison we have also evaluated the diffusion characteristics of Cu clusters on Cu(111) and compared results with previous findings [2]. Our results show a linear increase in effective energy barriers scaling almost as 0.043, 0.051 and 0.064 eV/atom for the Cu/Cu(111), Ag/Ag(111), and Ni/Ni(111) systems, respectively. For all three systems, diffusion of small islands proceeds mainly through concerted motion, although several multiple and single atom processes also contribute. [1] Oleg Trushin et al. Phys. Rev. B 72, 115401 (2005) [2] Altaf Karim et al. Phys. Rev. B 73, 165411 (2006)

  16. Impact of a molecular wetting layer on the structural and optical properties of tin(II)-phthalocyanine multilayers on Ag(111)

    Science.gov (United States)

    Gruenewald, Marco; Peuker, Julia; Meissner, Matthias; Sojka, Falko; Forker, Roman; Fritz, Torsten

    2016-03-01

    We investigate ultrathin highly ordered layers of tin(II)-phthalocyanine (SnPc) on top of a monolayer (ML) of 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) on Ag(111). The films are analyzed structurally by means of scanning tunneling microscopy (STM) and low-energy electron diffraction (LEED) as well as optically using differential reflectance spectroscopy (DRS). We find that the first ML of SnPc is entirely rearranged upon bilayer (BL) formation, yielding a commensurate registry in higher-order coincidence with the underlying PTCDA lattice. SnPc layers adsorbed on top self-assemble in further BLs. Within each BL the molecules are arranged pairwise, i.e., stacked as physical dimers, providing a characteristic absorption spectrum with strongly redshifted components compared to SnPc monomers. This altered spectral envelope mainly originates from strong orbital overlap of stacked molecules within each BL. In contrast, adjacent BLs show only weak orbital overlap, which is responsible for an additional redshift of the low-energy transition band. Our results demonstrate that a simple modification of the metal substrate surface, e.g., by a PTCDA wetting layer, has beneficial effects on structural ordering of SnPc multilayers adsorbed on top. The impact on the optical absorption spectrum manifests in a narrow and intense absorption peak in the near-infrared spectral region which is significantly less pronounced if the PTCDA layer is omitted.

  17. Synchrotron radiation applied to the study of heterogeneous model catalyst surfaces

    International Nuclear Information System (INIS)

    The application of synchrotron radiation-based experimental techniques for the characterization of model catalyst surfaces is reviewed. The planar model systems considered are distinguished by their heterogeneous surface character. Prototypical examples are discussed to illustrate various aspects of model catalyst surfaces and they include oxide thin films on metal single crystal substrates, metal nanoparticles deposited on ordered oxide films, thin layers of oxides on oxide substrates, heterogeneous bimetallic surfaces and metal single crystal surfaces decorated by oxide nanoparticles. (author)

  18. Complex Stoichiometry-Dependent Reordering of 3,4,9,10-Perylenetetracarboxylic Dianhydride on Ag(111) upon K Intercalation.

    Science.gov (United States)

    Zwick, Christian; Baby, Anu; Gruenewald, Marco; Verwüster, Elisabeth; Hofmann, Oliver T; Forker, Roman; Fratesi, Guido; Brivio, Gian Paolo; Zojer, Egbert; Fritz, Torsten

    2016-02-23

    Alkali metal atoms are frequently used for simple yet efficient n-type doping of organic semiconductors and as an ingredient of the recently discovered polycyclic aromatic hydrocarbon superconductors. However, the incorporation of dopants from the gas phase into molecular crystal structures needs to be controlled and well understood in order to optimize the electronic properties (charge carrier density and mobility) of the target material. Here, we report that potassium intercalation into the pristine 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) monolayer domains on a Ag(111) substrate induces distinct stoichiometry-dependent structural reordering processes, resulting in highly ordered and large KxPTCDA domains. The emerging structures are analyzed by low-temperature scanning tunneling microscopy, scanning tunneling hydrogen microscopy (ST[H]M), and low-energy electron diffraction as a function of the stoichiometry. The analysis of the measurements is corroborated by density functional theory calculations. These turn out to be essential for a correct interpretation of the experimental ST[H]M data. The epitaxy types for all intercalated stages are determined as point-on-line. The K atoms adsorb in the vicinity of the oxygen atoms of the PTCDA molecules, and their positions are determined with sub-Ångström precision. This is a crucial prerequisite for the prospective assessment of the electronic properties of such composite films, as they depend rather sensitively on the mutual alignment between donor atoms and acceptor molecules. Our results demonstrate that only the combination of experimental and theoretical approaches allows for an unambiguous explanation of the pronounced reordering of KxPTCDA/Ag(111) upon changing the K content. PMID:26718635

  19. Synchrotron x-ray diffraction study of liquid surfaces

    DEFF Research Database (Denmark)

    Als-Nielsen, Jens Aage; Pershan, P.S.

    1983-01-01

    A spectrometer for X-ray diffraction and refraction studies of horizontal, free surfaces of liquids is described. As an illustration smetic-A layering at the surface of a liquid crystal is presented.......A spectrometer for X-ray diffraction and refraction studies of horizontal, free surfaces of liquids is described. As an illustration smetic-A layering at the surface of a liquid crystal is presented....

  20. Probing droplets on superhydrophobic surfaces by synchrotron radiation scattering techniques

    KAUST Repository

    Accardo, Angelo

    2014-06-10

    Droplets on artificially structured superhydrophobic surfaces represent quasi contact-free sample environments which can be probed by X-ray microbeams and nanobeams in the absence of obstructing walls. This review will discuss basic surface wettability concepts and introduce the technology of structuring surfaces. Quasi contact-free droplets are compared with contact-free droplets; processes related to deposition and evaporation on solid surfaces are discussed. Droplet coalescence based on the electrowetting effect allows the probing of short-time mixing and reaction processes. The review will show for several materials of biological interest that structural processes related to conformational changes, nucleation and assembly during droplet evaporation can be spatially and temporally resolved by raster-scan diffraction techniques. Orientational ordering of anisotropic materials deposited during solidification at pinning sites facilitates the interpretation of structural data. 2014 International Union of Crystallography.

  1. Probing droplets on superhydrophobic surfaces by synchrotron radiation scattering techniques

    International Nuclear Information System (INIS)

    A comprehensive review about the use of micro- and nanostructured superhydrophobic surfaces as a tool for in situ X-ray scattering investigations of soft matter and biological materials. Droplets on artificially structured superhydrophobic surfaces represent quasi contact-free sample environments which can be probed by X-ray microbeams and nanobeams in the absence of obstructing walls. This review will discuss basic surface wettability concepts and introduce the technology of structuring surfaces. Quasi contact-free droplets are compared with contact-free droplets; processes related to deposition and evaporation on solid surfaces are discussed. Droplet coalescence based on the electrowetting effect allows the probing of short-time mixing and reaction processes. The review will show for several materials of biological interest that structural processes related to conformational changes, nucleation and assembly during droplet evaporation can be spatially and temporally resolved by raster-scan diffraction techniques. Orientational ordering of anisotropic materials deposited during solidification at pinning sites facilitates the interpretation of structural data

  2. Probing droplets on superhydrophobic surfaces by synchrotron radiation scattering techniques

    Energy Technology Data Exchange (ETDEWEB)

    Accardo, Angelo [Istituto Italiano di Tecnologia, Via Morego 30, Genova 16163 (Italy); Di Fabrizio, Enzo [KAUST (King Abdullah University of Science and Technology), Jeddah (Saudi Arabia); BIONEM Lab at University Magna Graecia, Campus Salvatore Venuta, Viale Europa 88100, Germaneto-Catanzaro (Italy); Limongi, Tania [KAUST (King Abdullah University of Science and Technology), Jeddah (Saudi Arabia); Marinaro, Giovanni [Istituto Italiano di Tecnologia, Via Morego 30, Genova 16163 (Italy); European Synchrotron Radiation Facility, BP 220, 38043 Grenoble Cedex (France); Riekel, Christian, E-mail: riekel@esrf.fr [European Synchrotron Radiation Facility, BP 220, 38043 Grenoble Cedex (France)

    2014-06-10

    A comprehensive review about the use of micro- and nanostructured superhydrophobic surfaces as a tool for in situ X-ray scattering investigations of soft matter and biological materials. Droplets on artificially structured superhydrophobic surfaces represent quasi contact-free sample environments which can be probed by X-ray microbeams and nanobeams in the absence of obstructing walls. This review will discuss basic surface wettability concepts and introduce the technology of structuring surfaces. Quasi contact-free droplets are compared with contact-free droplets; processes related to deposition and evaporation on solid surfaces are discussed. Droplet coalescence based on the electrowetting effect allows the probing of short-time mixing and reaction processes. The review will show for several materials of biological interest that structural processes related to conformational changes, nucleation and assembly during droplet evaporation can be spatially and temporally resolved by raster-scan diffraction techniques. Orientational ordering of anisotropic materials deposited during solidification at pinning sites facilitates the interpretation of structural data.

  3. Monochromator on a synchrotron undulator source for liquid surface studies

    DEFF Research Database (Denmark)

    Als-Nielsen, Jens Aage; Freund, A.K.

    1992-01-01

    For liquid surface studies a monochromatic beam of relative bandwidth between 0.1% and 1% at a variable angle in the vertical plane between 0-degrees and 10-degrees is needed. The beam should be like a sheet some tens of mu-m thick and some mm wide, and as intense as possible. We discuss a...... useful x rays, in full agreement with diffraction theory including secondary extinction. Heat load experiments reported elsewhere in this conference prove that Be crystals can withstand high beam power density and that the thermal deformation is small compared to the mosaic spread. The results of the...... flux calculations are most encouraging: a gain of order 10(3) to 10(4) can be expected as compared to existing liquid surface spectrometers....

  4. (Synchrotron studies of x-ray reflectivity from surfaces)

    Energy Technology Data Exchange (ETDEWEB)

    Pershan, P.S.

    1992-03-03

    Following a long period of theoretical interest, but only limited measurements, there has recently been an increased number of attempts to expand the relative paucity of experimental information on the structure of liquid surfaces using techniques as diverse as ellipsometry, micro-force balances, non-linear optics, Auger and photoelectron spectroscopy, and x-ray scattering. Our group has played a leading role in the currently expanding application of scattering techniques to the general problem of characterizing the microscopic structure of liquid surfaces and we propose here that this work be extended specifically to liquid metals. In the following sections we will briefly describe the salient features of x-ray scattering that are relevant to the current project, the progress that we have made in the current grant period and the work that we propose to carry out in the forthcoming grant period.

  5. Adsorbatinduzierte richtungsabhängige Facettierung und selbstorganisierte Domänen-Musterbildung auf vizinalen Ag(111)-Oberflächen

    OpenAIRE

    Schmitt, Stefan

    2007-01-01

    Die vorliegende Arbeit beschäftigt sich mit den strukturellen Aspekten einer adsorbat-induzierten Facettierung von vizinalen Ag(111)-Oberflächen. Bei dem Adsorbat handelte es sich um das organische Molekül Perylen-3,4,9,10-Tetracarbonsäure-Dianhydrid (PTCDA). Die Experimente wurden unter Ultrahochvakuum-Bedingungen durchgeführt, die Charakterisierung erfolgte hauptsächlich mit den Messmethoden Rastertunnelmikroskopie (STM) und niederenergetische Elektronenbeugung (LEED). Das planare Farbstoff...

  6. Photoelektronenspektroskopische Untersuchungen zur Adsorption und Reaktivität von Co(II)-, Zn(II)- und Fe(II)-Porphyrinen auf Ag(111)

    OpenAIRE

    Flechtner, Ken-Dominic

    2007-01-01

    Im Rahmen der vorliegenden Arbeit wurden verschiedene Metalloporphyrinschichten im Ultrahochvakuum auf Ag(111) bezüglich der Wechselwirkung mit der Silberoberfläche, der In Situ Herstellung solcher Metalloporphyrinschichten und der Koordination kleiner Moleküle in Axialposition untersucht. Das Ultrahochvakuum eröffnet dabei die Möglichkeit, die Eigenschaften, wie Reaktivität oder elektronische Struktur der Metalloporphyrine im lösungsmittelfreien Zustand zu studieren, d.h. störungsfrei zu cha...

  7. Surface photo reaction processes using synchrotron radiation; Hoshako reiki ni yoru hyomenko hanno process

    Energy Technology Data Exchange (ETDEWEB)

    Imaizumi, Y. [Tohoku University, Sendai (Japan). Institute for Materials Research; Yoshigoe, A. [Toyohashi University of Technology, Aichi (Japan); Urisu, T. [Toyohashi University of Technology, Aichi (Japan). Institute for Molecular Science

    1997-08-20

    This paper introduces the surface photo reaction processes using synchrotron radiation, and its application. A synchrotron radiation process using soft X-rays contained in electron synchrotron radiated light as an excited light source has a possibility of high-resolution processing because of its short wave length. The radiated light can excite efficiently the electronic state of a substance, and can induce a variety of photochemical reactions. In addition, it can excite inner shell electrons efficiently. In the aspect of its application, it has been found that, if radiated light is irradiated on surfaces of solids under fluorine-based reaction gas or Cl2, the surfaces can be etched. This technology is utilized practically. With regard to radiated light excited CVD process, it may be said that anything that can be deposited by the ordinary plasma CVD process can be deposited. Its application to epitaxial crystal growth may be said a nano processing application in thickness direction, such as forming an ultra-lattice structure, the application being subjected to expectation. In micromachine fabricating technologies, a possibility is searched on application of a photo reaction process of the radiated light. 5 refs., 6 figs.

  8. Hut clusters on Ge(001) surfaces studied by STM and synchrotron X-ray diffraction

    DEFF Research Database (Denmark)

    Nielsen, M.; Smilgies, D.-M.; Feidenhans'l, R.; Landemark, E.; Falkenberg, G.; Lottermoser, L.; Seehofer, L.; Johnson, R.L.

    entire surface. The huts are aligned with the [100] directions of the bulk Ge crystal and bounded by {103} facets. A structural model is proposed in which the clusters consist of Ge atoms and the dangling bonds on the {103} facets are saturated by In atoms which thereby stabilize the structure.......Nanoscale hut clusters formed on Ge(001) surfaces by depositing one monolayer of indium and annealing at temperatures between 350 and 500 degrees C were studied by scanning tunnelling microscopy and synchrotron X-ray diffraction. It was found that the hut clusters form regular arrays over the...

  9. Antiferroelectric surface layers in a liquid crystal as observed by synchrotron x-ray scattering

    DEFF Research Database (Denmark)

    Gramsbergen, E. F.; de Jeu, W. H.; Als-Nielsen, Jens Aage

    1986-01-01

    The X-ray reflectivity form the surface of a liquid crystal with terminally polar (cyano substituted) molecules has been studied using a high-resolution triple-axis X-ray spectrometer in combination with a synchrotron source. It is demonstrated that at the surface of the smectic Al phase a few...... antiferroelectric double layers develop that can be distinguished from the bulk single layer structure. A model is developed that separates the electron density in a contribution from the molecular form factor, and from the structure factor of the mono- and the bilayers, respectively. It shows that (i) the first...

  10. Probing droplets with biological colloidal suspensions on smart surfaces by synchrotron radiation micro- and nano-beams

    Science.gov (United States)

    Marinaro, G.; Accardo, A.; Benseny-Cases, N.; Burghammer, M.; Castillo-Michel, H.; Cotte, M.; Dante, S.; De Angelis, F.; Di Cola, E.; Di Fabrizio, E.; Hauser, C.; Riekel, C.

    2016-01-01

    Droplets with colloidal biological suspensions evaporating on substrates with defined wetting properties generate confined environments for initiating aggregation and self-assembly processes. We describe smart micro- and nanostructured surfaces, optimized for probing single droplets and residues by synchrotron radiation micro- and nanobeam diffraction techniques. Applications are presented for Ac-IVD and β-amyloid (1-42) peptides capable of forming cross-β sheet structures. Complementary synchrotron radiation FTIR microspectroscopy addresses secondary structure formation. The high synchrotron radiation source brilliance enables fast raster-scan experiments.

  11. Probing droplets with biological colloidal suspensions on smart surfaces by synchrotron radiation micro- and nano-beams

    KAUST Repository

    Marinaro, Giovanni

    2015-03-01

    Droplets with colloidal biological suspensions evaporating on substrates with defined wetting properties generate confined environments for initiating aggregation and self-assembly processes. We describe smart micro- and nanostructured surfaces, optimized for probing single droplets and residues by synchrotron radiation micro- and nanobeam diffraction techniques. Applications are presented for Ac-IVD and β-amyloid (1-42) peptides capable of forming cross-β sheet structures. Complementary synchrotron radiation FTIR microspectroscopy addresses secondary structure formation. The high synchrotron radiation source brilliance enables fast raster-scan experiments. © 2015 Elsevier Ltd.

  12. X-ray photoelectron spectroscopy study of synchrotron radiation irradiation of a polytetrafluoroethylene surface

    CERN Document Server

    Haruyama, Y; Matsui, S; Ideta, T; Ishigaki, H

    2003-01-01

    The effect of synchrotron radiation (SR) irradiation of a polytetrafluoroethylene (PTFE) surface was investigated using X-ray photoelectron spectroscopy (XPS). After the SR irradiation, the relative intensity of the F ls peak to the C ls peak decreased markedly. The chemical composition ratio to the F atoms to C atoms was estimated to be 0.29. From the curve fitting analysis of C ls and F ls XPS spectra, the chemical components and their intensity ratio were determined. The reason for the chemical composition change by the SR irradiation was discussed. (author)

  13. Interfacial charge rearrangement and intermolecular interactions: Density-functional theory study of free-base porphine adsorbed on Ag(111) and Cu(111)

    CERN Document Server

    Müller, Moritz; Maurer, Reinhard J; Reuter, Karsten

    2015-01-01

    We employ dispersion-corrected density-functional theory to study the adsorption of tetrapyrrole 2H-porphine (2H-P) at Cu(111) and Ag(111). Various contributions to adsorbate-substrate and adsorbate-adsorbate interactions are systematically extracted to analyze the self-assembly behavior of this basic building block to porphyrin-based metal-organic nanostructures. This analysis reveals a surprising importance of substrate-mediated van der Waals interactions between 2H-P molecules, in contrast to negligible direct dispersive interactions. The resulting net repulsive interactions rationalize the experimentally observed tendency for single molecule adsorption.

  14. Self-assembled two-dimensional nanoporous molecular arrays and photoinduced polymerization of 4-bromo-4′-hydroxybiphenyl on Ag(111)

    International Nuclear Information System (INIS)

    Self-assembled two-dimensional molecular arrays and photoinduced polymerization of 4-bromo-4′-hydroxybiphenyl on Ag(111) were studied using low-temperature scanning tunneling microscopy combined with density functional theory calculations. Square-like self-assembled structures of 4-bromo-4′-hydroxybiphenyl stabilized by intermolecular hydrogen and halogen bonds were transformed into hexagonal nanopores of biphenyl biradicals by 266 nm UV laser irradiation at 80 K. The biradicals further coupled to each other and formed covalently linked polyphenylene polymer chains at room temperature

  15. Self-assembled two-dimensional nanoporous molecular arrays and photoinduced polymerization of 4-bromo-4′-hydroxybiphenyl on Ag(111)

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Qian; He, Jing Hui [Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543 (Singapore); Singapore-Peking University Research Centre for a Sustainable Low-Carbon Future, 1 CREATE Way, #15-01, CREATE Tower, Singapore 138602 (Singapore); Zhang, Jia Lin [Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543 (Singapore); Department of Chemistry, School of Science, Tianjin University, Tianjin 300072 (China); Wu, Kai [Singapore-Peking University Research Centre for a Sustainable Low-Carbon Future, 1 CREATE Way, #15-01, CREATE Tower, Singapore 138602 (Singapore); BNLMS, SKLSCUSS, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China); Xu, Guo Qin [Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543 (Singapore); Singapore-Peking University Research Centre for a Sustainable Low-Carbon Future, 1 CREATE Way, #15-01, CREATE Tower, Singapore 138602 (Singapore); National University of Singapore (Suzhou) Research Institute, Suzhou (China); Wee, Andrew Thye Shen [Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542 (Singapore); Chen, Wei, E-mail: phycw@nus.edu.sg [Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543 (Singapore); Singapore-Peking University Research Centre for a Sustainable Low-Carbon Future, 1 CREATE Way, #15-01, CREATE Tower, Singapore 138602 (Singapore); National University of Singapore (Suzhou) Research Institute, Suzhou (China); Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542 (Singapore)

    2015-03-14

    Self-assembled two-dimensional molecular arrays and photoinduced polymerization of 4-bromo-4′-hydroxybiphenyl on Ag(111) were studied using low-temperature scanning tunneling microscopy combined with density functional theory calculations. Square-like self-assembled structures of 4-bromo-4′-hydroxybiphenyl stabilized by intermolecular hydrogen and halogen bonds were transformed into hexagonal nanopores of biphenyl biradicals by 266 nm UV laser irradiation at 80 K. The biradicals further coupled to each other and formed covalently linked polyphenylene polymer chains at room temperature.

  16. Surface-enhanced Raman scattering active gold nanostructure fabricated by photochemical reaction of synchrotron radiation

    International Nuclear Information System (INIS)

    The deposition of gold nanoparticles in an electroplating solution containing gold (I) trisodium disulphite under synchrotron X-ray radiation was investigated. The nanoparticles grew and aggregated into clusters with increasing radiation time. This behavior is explained by evaluating the effect of Derjaguin-Landau-Verweyand-Overbeek (DLVO) interactions combining repulsive electrostatic and attractive van der Waals forces on the particle deposition process. The surface-enhanced Raman scattering (SERS) of 4,4′ -bipyridine (4bpy) in aqueous solution was measured using gold nanoparticles immobilized on silicon substrates under systematically-varied X-ray exposure. The substrates provided an in situ SERS spectrum for 1 nM 4bpy. This demonstration creates new opportunities for chemical and environmental analyses through simple SERS measurements. - Highlights: • Gold nanoparticles were produced by photochemical reaction of synchrotron radiation. • The gold nanoparticles grew and aggregated into the higher-order nanostructure. • The behavior is qualitatively explained by analytical estimation. • The surface-enhanced Raman spectroscopy of 4,4′-bipyridine (4bpy) was demonstrated. • The substrate fabricated in a suitable condition provides in situ SERS for 1 nM 4bpy

  17. Surface-enhanced Raman scattering active gold nanostructure fabricated by photochemical reaction of synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Yamaguchi, Akinobu, E-mail: yamaguti@lasti.u-hyogo.ac.jp [Laboratory of Advance Science and Technology for Industry, University of Hyogo, 3-1-2 Koto, Kamigori, Ako, Hyogo 678-1205 (Japan); Matsumoto, Takeshi [Laboratory of Advance Science and Technology for Industry, University of Hyogo, 3-1-2 Koto, Kamigori, Ako, Hyogo 678-1205 (Japan); Okada, Ikuo; Sakurai, Ikuya [Synchrotoron Radiation Research Center, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8603 (Japan); Utsumi, Yuichi [Laboratory of Advance Science and Technology for Industry, University of Hyogo, 3-1-2 Koto, Kamigori, Ako, Hyogo 678-1205 (Japan)

    2015-06-15

    The deposition of gold nanoparticles in an electroplating solution containing gold (I) trisodium disulphite under synchrotron X-ray radiation was investigated. The nanoparticles grew and aggregated into clusters with increasing radiation time. This behavior is explained by evaluating the effect of Derjaguin-Landau-Verweyand-Overbeek (DLVO) interactions combining repulsive electrostatic and attractive van der Waals forces on the particle deposition process. The surface-enhanced Raman scattering (SERS) of 4,4′ -bipyridine (4bpy) in aqueous solution was measured using gold nanoparticles immobilized on silicon substrates under systematically-varied X-ray exposure. The substrates provided an in situ SERS spectrum for 1 nM 4bpy. This demonstration creates new opportunities for chemical and environmental analyses through simple SERS measurements. - Highlights: • Gold nanoparticles were produced by photochemical reaction of synchrotron radiation. • The gold nanoparticles grew and aggregated into the higher-order nanostructure. • The behavior is qualitatively explained by analytical estimation. • The surface-enhanced Raman spectroscopy of 4,4′-bipyridine (4bpy) was demonstrated. • The substrate fabricated in a suitable condition provides in situ SERS for 1 nM 4bpy.

  18. Application of X-rays and Synchrotron X Rays to Residual Stress Evaluation Near Surfaces

    International Nuclear Information System (INIS)

    A nondestructive residual stress analysis can be performed using diffraction methods. The easiest accessible radiation is characteristic X radiation that has a penetration depth of ∼10 microm suitable for the determination of the residual stresses in near-surface layers. Special techniques have been developed, e.g., with respect to in situ analyses of the stress state in oxide layers and the residual stress analysis in coarse grained zones of steel welds or annealed Ni-base alloys. Depending on the size of the gauge volume, neutron diffraction can provide information at depths of tens of millimetres of steel and many tens of millimetres of Al. An alternative to the use of the characteristic synchrotron radiation is the use of a high-energy polychromatic beam in an energy dispersive arrangement, which gives access to higher penetration depths at still gauge volumes as small as 100 microm x 100 microm x 1 mm in steel rods of 15-mm diameter. The combination of neutrons with conventional X rays and monochromatic and polychromatic synchrotron radiation allows for a comprehensive investigation of the phase composition, the texture, and the residual stresses

  19. Assessment of barium sulphate formation and inhibition at surfaces with synchrotron X-ray diffraction (SXRD)

    International Nuclear Information System (INIS)

    The precipitation of barium sulphate from aqueous supersaturated solutions is a well-known problem in the oil industry often referred to as 'scaling'. The formation and growth of barite on surfaces during the oil extraction process can result in malfunctions within the oil facilities and serious damage to the equipment. The formation of barium sulphate at surfaces remains an important topic of research with the focus being on understanding the mechanisms of formation and means of control. In situ synchrotron X-ray diffraction (SXRD) was used to investigate the formation of barium sulphate on a stainless steel surface. The effect of Poly-phosphinocarboxylic acid (PPCA) and Diethylenetriamine-penta-methylenephosphonic acid (DETPMP) which are two commercial inhibitors for barium sulphate was examined. The in situ SXRD measurements allowed the identification of the crystal faces of the deposited barite in the absence and presence of the two inhibitors. The preferential effect of the inhibitors on some crystal planes is reported and the practical significance discussed.

  20. Ion distributions at charged aqueous surfaces: Synchrotron X-ray scattering studies

    International Nuclear Information System (INIS)

    Surface sensitive synchrotron X-ray scattering studies were performed to obtain the distribution of monovalent ions next to a highly charged interface at room temperature. To control surface charge density, lipids, dihexadecyl hydrogen-phosphate (DHDP) and dimysteroyl phosphatidic acid (DMPA), were spread as monolayer materials at the air/water interface, containing CsI at various concentrations. Five decades in bulk concentrations (CsI) are investigated, demonstrating that the interfacial distribution is strongly dependent on bulk concentration. We show that this is due to the strong binding constant of hydronium H3O+ to the phosphate group, leading to proton-transfer back to the phosphate group and to a reduced surface charge. Using anomalous reflectivity off and at the L3 Cs+ resonance, we provide spatial counterion (Cs+) distributions next to the negatively charged interfaces. The experimental ion distributions are in excellent agreement with a renormalized surface charge Poisson-Boltzmann theory for monovalent ions without fitting parameters or additional assumptions. Energy Scans at four fixed momentum transfers under specular reflectivity conditions near the Cs+ L3 resonance were conducted on 10-3 M CsI with DHDP monolayer materials on the surface. The energy scans exhibit a periodic dependence on photon momentum transfer. The ion distributions obtained from the analysis are in excellent agreement with those obtained from anomalous reflectivity measurements, providing further confirmation to the validity of the renormalized surface charge Poisson-Boltzmann theory for monovalent ions. Moreover, the dispersion corrections f0 and f00 for Cs+ around L3 resonance, revealing the local environment of a Cs+ ion in the solution at the interface, were extracted simultaneously with output of ion distributions.

  1. Ion distributions at charged aqueous surfaces: Synchrotron X-ray scattering studies

    Energy Technology Data Exchange (ETDEWEB)

    Bu, Wei [Iowa State Univ., Ames, IA (United States)

    2009-01-01

    Surface sensitive synchrotron X-ray scattering studies were performed to obtain the distribution of monovalent ions next to a highly charged interface at room temperature. To control surface charge density, lipids, dihexadecyl hydrogen-phosphate (DHDP) and dimysteroyl phosphatidic acid (DMPA), were spread as monolayer materials at the air/water interface, containing CsI at various concentrations. Five decades in bulk concentrations (CsI) are investigated, demonstrating that the interfacial distribution is strongly dependent on bulk concentration. We show that this is due to the strong binding constant of hydronium H3O+ to the phosphate group, leading to proton-transfer back to the phosphate group and to a reduced surface charge. Using anomalous reflectivity off and at the L3 Cs+ resonance, we provide spatial counterion (Cs+) distributions next to the negatively charged interfaces. The experimental ion distributions are in excellent agreement with a renormalized surface charge Poisson-Boltzmann theory for monovalent ions without fitting parameters or additional assumptions. Energy Scans at four fixed momentum transfers under specular reflectivity conditions near the Cs+ L3 resonance were conducted on 10-3 M CsI with DHDP monolayer materials on the surface. The energy scans exhibit a periodic dependence on photon momentum transfer. The ion distributions obtained from the analysis are in excellent agreement with those obtained from anomalous reflectivity measurements, providing further confirmation to the validity of the renormalized surface charge Poisson-Boltzmann theory for monovalent ions. Moreover, the dispersion corrections f0 and f00 for Cs+ around L3 resonance, revealing the local environment of a Cs+ ion in the solution at the interface, were extracted simultaneously with output of ion distributions.

  2. Synchrotron radiation induced direct photo-etching and surface modification of PTFE

    International Nuclear Information System (INIS)

    In the first part of this article, we have described and discussed the measurement results of etching rates by direct photo-etching using Synchrotron Radiation (SR) for various kind of crosslinked PTFEs, which were prepared by different crosslinking doses, comparing with the non-crosslinked PTFE. It has been found that the etching rates obtained for crosslinked PTFE were much larger than that of non-crosslinked one. These results are not described by simple consideration such as the G values of main chain scission. We propose that the etching rates should be discussed by the complex mechanism through at least two different steps such as polymer decomposition and fragment desorption. In the second part of the article, we have described and discussed the abnormal reaction induced at the surface region after the SR etching for non-crosslinked PTFE. Through the measurements using DSC and solid state 19F-NMR, we have confirmed the crosslinking reaction of PTFE even in solid state PTFE. This should be induced by the very high density radical formation in very thin area of PTFE films by SR radiation. (author)

  3. 3-D surface profile measurements of large x-ray synchrotron radiation mirrors using stitching interferometry

    International Nuclear Information System (INIS)

    Stitching interferometry, using small-aperture, high-resolution, phase-measuring interferometry, has been proposed for quite some time now as a metrology technique to obtain 3-dimensional profiles of surfaces of oversized optical components and substrates. The aim of this work is to apply this method to the specific case of long grazing-incidence x-ray mirrors, such as those used in beamlines at synchrotron radiation facilities around the world. Both fabrication and characterization of these mirrors would greatly benefit from this technique because it offers the potential for providing measurements with accuracy and resolution better than those obtained using existing noncontact laser profilers, such as the long trace profiler (LTP). Measurement data can be used as feedback for computer-controlled fabrication processes to correct for possible topography errors. The data can also be used for simulating and predicting mirror performance under realistic conditions. A semiautomated stitching system was built and tested at the X-ray Optics Metrology Laboratory of the Advanced Photon Source at Argonne National Laboratory. The initial objective was to achieve a measurement sensitivity on the order of 1 (micro)rad rms. Preliminary tests on a 1 m-long x-ray mirror showed system repeatability of less than 0.6 (micro)rad rms. This value is comparable to that of a conventional LTP. The measurement accuracy was mostly affected by environmental perturbations and system calibration effects. With a fully automated and improved system (to be built in the near future), we expect to achieve measurement sensitivity on the order of 0.0 (micro)rad rms or better. In this paper, after a brief review of basic principles and general technical difficulties and challenges of the stitching technique, a detailed description of the measurement setup is given and preliminary results obtained with it are analyzed and discussed

  4. Study of strong enhancement of synchrotron radiation via surface plasma waves excitation by particle-in-cell simulations

    Energy Technology Data Exchange (ETDEWEB)

    Pan, K. Q. [Center for Applied Physics and Technology, Peking University, Beijing 100871 (China); Key Laboratory of High Energy Density Physics Simulation, Ministry of Education, Peking University, Beijing 100871 (China); Zheng, C. Y., E-mail: zhengcy@iapcm.ac.cn; Cao, L. H.; He, X. T., E-mail: xthe@iapcm.ac.cn [Center for Applied Physics and Technology, Peking University, Beijing 100871 (China); Key Laboratory of High Energy Density Physics Simulation, Ministry of Education, Peking University, Beijing 100871 (China); Institute of Applied Physics and Computational Mathematics, Beijing 100088 (China); Wu, Dong [Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China); Liu, Z. J. [Institute of Applied Physics and Computational Mathematics, Beijing 100088 (China)

    2015-11-02

    Synchrotron radiation is strongly enhanced by the resonant excitation of surface plasma waves (SPWs). Two-dimensional particle-in-cell simulations show that energy conversion efficiency from laser to radiation in the case of SPWs excitation is about 18.7%, which is improved by more than 2 orders of magnitude compared with that of no SPWs excitation. Besides the high energy conversion efficiency, the frequency spectrum and the angular distribution of the radiation are also improved in the case of SPWs excitation because of the quasi-static magnet field induced by surface plasma waves excitation.

  5. Study of strong enhancement of synchrotron radiation via surface plasma waves excitation by particle-in-cell simulations

    International Nuclear Information System (INIS)

    Synchrotron radiation is strongly enhanced by the resonant excitation of surface plasma waves (SPWs). Two-dimensional particle-in-cell simulations show that energy conversion efficiency from laser to radiation in the case of SPWs excitation is about 18.7%, which is improved by more than 2 orders of magnitude compared with that of no SPWs excitation. Besides the high energy conversion efficiency, the frequency spectrum and the angular distribution of the radiation are also improved in the case of SPWs excitation because of the quasi-static magnet field induced by surface plasma waves excitation

  6. Experiments of synchrotron injection using the direct fast chopped H- beam extracted from surface-plasma-type negative hydrogen ion source

    International Nuclear Information System (INIS)

    An experiment of synchrotron injection using the direct fast chopped H- beam extracted from a surface-plasma-type H- ion source has been successfully achieved. The injection phase of the fast chopped beam from linac into the booster synchrotron is adjustable against the center of rf bucket by using this beam. It was obtained that the longitudinal emittance was controlled at the extraction of the booster synchrotron, and that the beam loss during the injection into main ring of the KEK-PS was reduced by this fast chopped beam. (author)

  7. X-ray diffraction analysis of rust layer on a weathering steel bridge with surface treatment using synchrotron radiation

    International Nuclear Information System (INIS)

    We have examined the structure of rust layer formed on a weathering steel bridge, to which the surface treatment, employing the effect of Cr2(SO4)3 sophisticatedly designed to form the protective goethite (α-FeOOH) rust layer which contains a certain amount of Cr, Cr-goethite, was applied in 1996, using X-ray diffraction at SPring-8 synchrotron radiation facility. It was shown that the formation of α-FeOOH was promoted and/or crystal growth of γ-FeOOH was suppressed by the surface treatment. The increase in the protective ability index (PAI) of the rust layer indicates that the protective goethite was predominantly formed under the effect of the surface treatment. In conclusion, it can be said that the surface treatment worked well to promote the formation of the protective goethite rust layer on the weathering steel bridge during the 10-year exposure. (author)

  8. Observation and modeling of conformational molecular structures driving the self-assembly of tri-adamantyl benzene on Ag(111).

    Science.gov (United States)

    Calmettes, Bastien; Estrampes, Nicolas; Coudret, Christophe; Roussel, Thomas J; Faraudo, Jordi; Coratger, Roland

    2016-07-27

    The self-organization of tri-adamantyl (TAB) benzene molecules has been investigated using low temperature scanning tunneling microscopy (LT-STM). The molecular structures have also been studied using molecular modeling. In particular, these calculations have been performed on large areas (1000 nm(2)) from the atomic structure of the molecular building block, combining molecular dynamics (MD) and Monte-Carlo (MC) approaches. These investigations show that the structure of the molecule and its flexibility allow for the formation of different networks as a function of surface coverage. The calculations demonstrate that the stability of the largest structures is obtained through the increase of the interfacial energy induced by the rotation of the adamantyl groups, a behavior whose consequences explain the subtle contrasts observed in the experimental STM images. PMID:26667964

  9. Application of x rays and synchrotron x rays to residual stress evaluation near surfaces

    International Nuclear Information System (INIS)

    The significance of residual stresses with respect to the mechanical and technological properties of components has been acknowledged for almost 1 1/2 centuries now. Since by definition the residual stresses are balanced throughout the whole body, a determination of the residual stress distribution is necessary--not just the value at a single location. To find local extrema, the method used for residual stress analysis must be chosen appropriate to the residual stress topology. The combination of neutrons with conventional X-rays and monochromatic and polychromatic synchrotron radiation allows for a comprehensive investigation of the phase composition, the texture, and the residual stresses

  10. Construction of the undulator beamline equipped with a UHV-STM for observations of synchrotron-radiation-stimulated surface reaction

    International Nuclear Information System (INIS)

    An undulator beamline equipped with a UHV-scanning tunneling electron microscopy (STM) system has been designed and constructed at the UVSOR facility to investigate synchrotron-radiation-stimulated reactions. Using this undulator beamline, we have observed irradiation effects on the hydrogen terminated-(H-) Si(1 1 1) surfaces in atomic scale. The small protrusions, which are assigned to the rest-atom with missing H, appeared on the monohydride surface after irradiation. The density of them monotonically increased with irradiation dose. This phenomenon has been observed almost independent on the Si 2p core electron excitation threshold, indicating the significant contribution of the valence electron excitations to the Si-H bond dissociations

  11. Fast in situ phase and stress analysis during laser surface treatment: a synchrotron x-ray diffraction approach.

    Science.gov (United States)

    Kostov, V; Gibmeier, J; Wilde, F; Staron, P; Rössler, R; Wanner, A

    2012-11-01

    An in situ stress analysis by means of synchrotron x-ray diffraction was carried out during laser surface hardening of steel. A single exposure set-up that based on a special arrangement of two fast silicon strip line detectors was established, allowing for fast stress analysis according to the sin(2)ψ x-ray analysis method. For the in situ experiments a process chamber was designed and manufactured, which is described in detail. First measurements were carried out at the HZG undulator imaging beamline (IBL, beamline P05) at the synchrotron storage ring PETRA III, DESY, Hamburg (Germany). The laser processing was carried out using a 6 kW high power diode laser system. Two different laser optics were compared, a Gaussian optic with a focus spot of ø 3 mm and a homogenizing optic with a rectangular spot dimension of 8 × 8 mm(2). The laser processing was carried out using spot hardening at a heating-/cooling rate of 1000 K/s and was controlled via pyrometric temperature measurement using a control temperature of 1150 °C. The set-up being established during the measuring campaign allowed for this first realization data collection rates of 10Hz. The data evaluation procedure applied enables the separation of thermal from elastic strains and gains unprecedented insight into the laser hardening process. PMID:23206092

  12. Surface and bulk sensitive measurements of polarized XANES using synchrotron radiation

    International Nuclear Information System (INIS)

    XANES ( X-ray Absorption Near Edge Structure) with polarized synchrotron light is now established to be one of the important techniques for the study of electronic structure of HTc superconductors in respect of finding out the symmetry of holes and their implication to the theoretical model proposed to explain superconductivity in these cuprates. The XANES spectra measured by two methods namely, total yield (TY) and fluorescence yield (FY) have given different results in respect of out-of-plane Cu 3d symmetry holes. The reason of this discrepancy is still unclear. In this communication, we report our polarized XANES measurements on Bi-2212 single crystal at the Cu L3 edge by TY and FY methods and discuss the results in detail. (author). 19 refs., 5 figs

  13. Surface assisted oxidation of flat lying organic molecules - a real-time STM study

    Energy Technology Data Exchange (ETDEWEB)

    Waldmann, Thomas; Roos, Michael; Breitruck, Achim; Hoster, Harry E.; Behm, R. Juergen [Institute of Surface Chemistry and Catalysis, Ulm University, D-89069 Ulm (Germany); Kuenzel, Daniela; Gross, Axel [Institute of Theoretical Chemistry, Ulm University, D-89069 Ulm (Germany)

    2010-07-01

    Using time resolved scanning tunneling microscopy (STM), we tested the interaction of O{sub 2} from gas-phase with ordered adlayers of the Bis(terpyridine) derivative 2,4'-BTP on Au(111), Ag(111) and graphite (HOPG) surfaces at T = 300 K. At an O{sub 2} pressure of 10{sup -5} mbar, the adlayers on Ag(111) undergo chemical and structural changes. These include modifications of the 2-pyridyl rings of individual 2,4'-BTP adsorbates and rearrangements of the hydrogen bonded adlayer. Since we do not observe similar changes on HOPG and Au(111), we assume that Ag(111) acts as catalyst for the underlying processes. Based on our STM data in combination with DFT calculations, we conclude that the observed reaction is pyridyl-N-oxide formation. Furthermore, we derive reaction yields, enantiomeric excess, reaction rates and reaction orders from the time-resolved STM data.

  14. Interplay of adsorbate-adsorbate and adsorbate-substrate interactions in self-assembled molecular surface nanostructures

    DEFF Research Database (Denmark)

    Schnadt, Joachim; Xu, Wei; Vang, Ronnie Thorbjørn;

    2010-01-01

    The adsorption of 2,6-naphthalenedicarboxylic acid (NDCA) molecules on the Ag(110), Cu(110), and Ag(111) surfaces at room temperature has been studied by means of scanning tunnelling microscopy (STM). Further supporting results were obtained using X-ray photoelectron spectroscopy (XPS) and soft X......-ray absorption spectroscopy (XAS). On the Ag(110) support, which had an average terrace width of only 15 nm, the NDCA molecules form extended one-dimensional (1-D) assemblies, which are oriented perpendicular to the step edges and have lengths of several hundred nanometres. This shows that the assemblies have a......-edge crossing is not observed when the molecules are adsorbed on the isotropic Ag(111) or more reactive Cu(110) surfaces. On Ag(111), similar 1-D assemblies are formed to those on Ag(110), but they are oriented along the step edges. On Cu(110), the carboxylic groups of NDCA are deprotonated and form covalent...

  15. Expectation for medium-sized highly brilliant synchrotron radiation ring. Prospects for soft X-ray surface/interface sciences

    International Nuclear Information System (INIS)

    The use of medium-sized highly brilliant soft X-ray synchrotron radiation (SR) enables analyses with much better spatial, energy and time resolution, resulting in visualizing surface/interface electronic structure in nano regions. In order to improve performances of electronic, magnetic and energy devices, it is required to characterize and control electronic structures. In the world, several SR rings with the emittance of less than 1 nmrad are being constructed, aiming at revolutionary progress of surface/interface sciences using soft X-rays. Although we have constructed the University of Tokyo Outstation at SPring-8 for soft X-ray surface/interface sciences, medium-sized highly brilliant SR ring is strongly required for further development in this field. In this article, nano-region photoelectron spectroscopy for graphene FET and ReRAM, soft X-ray emission spectroscopy for fuel cells and Li ion batteries, and time-resolved photoelectron spectroscopy for photocatalysts are introduced, and future prospects of soft X-ray surface/interface sciences are discussed. (author)

  16. Surface alloying in the Sn/Ni(111) system studied by synchrotron radiation photoelectron valence band spectroscopy and ab-initio density of states calculations

    Czech Academy of Sciences Publication Activity Database

    Karakalos, S.; Ladas, S.; Janeček, P.; Šutara, F.; Nehasil, V.; Tsud, N.; Prince, K.; Matolín, V.; Cháb, Vladimír; Papanicolaou, N.I.; Dianat, A.; Gross, A.

    2008-01-01

    Roč. 516, č. 10 (2008), s. 2962-2965. ISSN 0040-6090 Institutional research plan: CEZ:AV0Z10100521 Keywords : surface alloys * electronic structure calculations * photoelectron spectroscopy * synchrotron radiation Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.884, year: 2008

  17. New Analytical Methods for the Surface/Interface and the Micro-Structures in Advanced Nanocomposite Materials by Synchrotron Radiation

    International Nuclear Information System (INIS)

    Analytical methods of surface/interface structure and micro-structure in advanced nanocomposite materials by using the synchrotron radiation are introduced. Recent results obtained by the energy-tunable and highly collimated brilliant X-rays, in-situ wide angle/small angle X-ray diffraction with high accuracy are reviewed. It is shown that small angle X-ray scattering is one of the best methods to characterize nanoparticle dispersibility, filler aggregate/agglomerate structures and in-situ observation of hierarchical structure deformation in filled rubber under cyclic stretch. Grazing Incidence(small and wide angle) X-ray Scattering are powerful to analyze the sintering process of metal nanoparticle by in-situ observation as well as the orientation of polymer molecules and crystalline orientation at very thin surface layer (ca 7nm) of polymer film. While the interaction and conformation of adsorbed molecule at interface can be investigated by using high energy X-ray XPS with Enough deep position (ca 9 micron m). (author)

  18. New Analytical Methods for the Surface/ Interface and the Micro-Structures in Advanced Nanocomposite Materials by Synchrotron Radiation

    Directory of Open Access Journals (Sweden)

    K. Nakamae

    2010-12-01

    Full Text Available Analytical methods of surface/interface structure and micro-structure in advanced nanocomposite materials by using the synchrotron radiation are introduced. Recent results obtained by the energy-tunable and highly collimated brilliant X-rays, in-situ wide angle/small angle X-ray diffraction with high accuracy are reviewed. It is shown that small angle X-ray scattering is one of the best methods to characterize nanoparticle dispersibility, filler aggregate/agglomerate structures and in-situ observation of hierarchical structure deformation in filled rubber under cyclic stretch. Grazing Incidence(small and wide angle X-ray Scattering are powerful to analyze the sintering process of metal nanoparticle by in-situ observation as well as the orientation of polymer molecules and crystalline orientation at very thin surface layer (ca 7nm of polymer film. While the interaction and conformation of adsorbed molecule at interface can be investigated by using high energy X-ray XPS with Enough deep position (ca 9 micron m.

  19. Selective surface functionalization of polystyrene induced by synchrotron or UV radiation in the presence of oxygen or acrylic acid vapors

    International Nuclear Information System (INIS)

    Efficient surface functionalization of Polystyrene (PS) thin films by electromagnetic radiation in combination with a reactive gaseous atmosphere was obtained. Monochromatic synchrotron (SR) or polychromatic UV radiation were used as excitation sources. When SR was used, O2 was introduced after irradiation into the UHV chamber. UV irradiation was carried out keeping a constant flow of O2 or acrylic acid (AA) vapors during the photolysis. FTIR-ATR and XPS-NEXAFS spectra were obtained at the UFRGS and the LNLS, Campinas respectively. PS films were functionalized by monochromatic SR and then expose to O2 at specific transitions such us C 1s →σ*C-C excitation. It was found a high rate of COO, C=O and C-O groups at the surface (> 70%). UV-assisted treatment in the presence of AA vapors showed that an efficient polymerization process took place, such as, it was observed in previous AA low pressure RF plasma treatments. UV-assisted functionalization has the advantage of lower costs and simple set-up compared to plasma treatments. (author)

  20. Synchrotron radiation

    International Nuclear Information System (INIS)

    The paper on Synchrotron Radiation contains the appendix to the Daresbury Annual Report 1987/88. The appendix is mainly devoted to the scientific progress reports on the work at the Synchrotron Radiation Source in 1987/8. The parameters of the Experimental Stations and the index to the Scientific Reports are also included in the appendix. (U.K.)

  1. Synchrotron light

    International Nuclear Information System (INIS)

    'Synchrotron Light' is an interactive and detailed introduction to the physics and technology of the generation of coherent radiation from accelerators as well as to its widespread high-tech applications in science, medicine and engineering. The topics covered are the interaction of light and matter, the technology of synchrotron light sources, spectroscopy, imaging, scattering and diffraction of X-rays, and applications to materials science, biology, biochemistry, medicine, chemistry, food and pharmaceutical technology. All synchrotron light facilities are introduced with their home-page addresses. 'Synchrotron Light' provides an instructive and comprehensive multimedia learning tool for students, experienced practitioners and novices wishing to apply synchrotron radiation in their future work. Its multiple-entry points permit an easy exploration of the CD-Rom according to the users knowledge and interest. 2-D and 3-D animations and virtual reconstruction with computer-generated images guide visitors into the scientific and technical world of a synchrotron and into the applications of synchrotron radiation. This bilingual (English and French) CD-Rom can be used for self-teaching and in courses at various levels in physics, chemistry, engineering, and biology. (author)

  2. [Synchrotron studies of x-ray reflectivity from surfaces]. Technical progress report

    Energy Technology Data Exchange (ETDEWEB)

    Pershan, P.S.

    1992-03-03

    Following a long period of theoretical interest, but only limited measurements, there has recently been an increased number of attempts to expand the relative paucity of experimental information on the structure of liquid surfaces using techniques as diverse as ellipsometry, micro-force balances, non-linear optics, Auger and photoelectron spectroscopy, and x-ray scattering. Our group has played a leading role in the currently expanding application of scattering techniques to the general problem of characterizing the microscopic structure of liquid surfaces and we propose here that this work be extended specifically to liquid metals. In the following sections we will briefly describe the salient features of x-ray scattering that are relevant to the current project, the progress that we have made in the current grant period and the work that we propose to carry out in the forthcoming grant period.

  3. Synchrotron radiation

    International Nuclear Information System (INIS)

    Work at the Daresbury SRS has of necessity been interrupted this year (1991/92) due to the incorporation of Wiggler II. However, considerable beamtime was awarded before the shutdown and the major part of this appendix is concerned with the progress reports of the research undertaken then. The reports have been organised under the following broad headings: Molecular Science (19 papers), Surface and Materials Science (169 papers), Biological Science (85 papers), Instrumental and Technique Developments (13 papers) and Accelerator Physics (3 papers). It is hoped that in time the number of contributions on accelerator physics will grow to reflect the in-house activity on, for example, accelerator improvement and design. The research reports are preceded by the Annual Report of the Synchrotron Radiation Facilities Committee, which outlines the research highlights identified by that Committee (also included are details of the current membership of the SRFC and the chairmen of the Beamtime Allocation Panels). Following the reports are the specifications for the beamlines and stations. This year Section 3 contains 289 reports (nearly 100 more than last year) and the number of publications, generated by scientists and engineers who have used or are associated with Daresbury Laboratory facilities, has topped 500 for the first time. (author)

  4. Synchrotron radiation

    International Nuclear Information System (INIS)

    A detailed account of the research work associated with the Synchrotron Radiation Source at Daresbury Laboratory, United Kingdom, in 1984/85, is presented in the Appendix to the Laboratory's Annual Report. (U.K.)

  5. Synchrotron radiation

    International Nuclear Information System (INIS)

    Synchrotron radiation has had a revolutionary effect on a broad range of scientific studies, from physics, chemistry and metallurgy to biology, medicine and geoscience. The situation during the last decade has been one of very rapid growth, there is a great vitality to the field and a capability has been given to a very broad range of scientific disciplines which was undreamt of just a decade or so ago. In this paper, the authors discuss some of the properties of synchrotron radiation that makes it so interesting and something of the sources in existence today including the National Synchrotron Light Source (NSLS). The NSLS is one of the new facilities built specifically for synchrotron radiation research and the model that was developed there for involvement of the scientific community is a good one which provides some good lessons for these facilities and others

  6. Synchrotron radiation

    International Nuclear Information System (INIS)

    A report is given on the work involving the Synchrotron Radiation Division of the Daresbury Laboratory during the period January 1981 - March 1982. Development of the source, beamlines and experimental stations is described. Progress reports from individual investigators are presented which reveal the general diversity and interdisciplinary nature of the research which benefits from access to synchrotron radiation and the associated facilities. Information is given on the organisation of the Division and publications written by the staff are listed. (U.K.)

  7. Synchrotron radiation

    International Nuclear Information System (INIS)

    The paper on synchrotron radiation is the appendix to the Daresbury (United Kingdom) annual report, 1985/86. The bulk of the volume is made up of the progress reports for the work carried out during the year under review using the Synchrotron Radiation Source (SRS) at Daresbury. The Appendix also contains: the scientific programmes at the the SRS, progress on beamlines, instrumentation and computing developments, and activities connected with accelerator development. (U.K.)

  8. Surface photo-voltage effect on Cr/GaAs(100) studied by photoemission spectroscopy with the combination of synchrotron radiation and laser

    Science.gov (United States)

    Takahashi, Kazutoshi; Tokudomi, Sinji; Nagata, Yusuke; Azuma, Junpei; Kamada, Masao

    2011-12-01

    The surface photo-voltage (SPV) effect and its temporal profile on a Cr/p-GaAs(100) surface were measured by core-level photoelectron spectroscopy with the combination of synchrotron radiation and laser. It was found that the SPV value at the Cr thickness of 0.05 and 0.1 nm is enhanced in comparison with the clean surface, while that at the Cr thickness larger than 0.2 nm is remarkably suppressed. The dependence on the Cr thickness can be interpreted in terms of the change in the band bending and the escape process, which are associated with the electronic structures induced by the Cr deposition.

  9. Stress distribution in mechanically surface treated Ti-2.5Cu determined by combining energy-dispersive synchrotron and neutron diffraction

    International Nuclear Information System (INIS)

    Mechanical surface treatments such as shot peening (SP) or ball-burnishing (BB) induce plastic deformation close to the surface resulting in work-hardening and compressive residual stresses. It enhances the fatigue performance by retarding or even suppressing micro-crack growth from the surface into the interior. SP and BB were carried out on a solution heat treated (SHT) Ti-2.5Cu. The investigations of compressive and balancing tensile residual stresses need a combination of energy-dispersive synchrotron (ED) and neutron diffraction. Essential for the stress distribution is the stress state before surface treatments which was determined by neutron diffraction. Results show that the maximum compressive stress and its depth play an important role to improve the fatigue performance.

  10. Surface-confined Ullmann coupling of thiophene substituted porphyrins

    Science.gov (United States)

    Beggan, J. P.; Boyle, N. M.; Pryce, M. T.; Cafolla, A. A.

    2015-09-01

    The covalent coupling of (5,10,15,20-tetrabromothien-2-ylporphyrinato)zinc(II) (TBrThP) molecules on the Ag(111) surface has been investigated under ultra-high-vacuum conditions, using scanning tunnelling microscopy and x-ray photoelectron spectroscopy. The findings provide atomic-level insight into surface-confined Ullmann coupling of thiophene substituted porphyrins, analyzing the progression of organometallic intermediate to final coupled state. Adsorption of the TBrThP molecules on the Ag(111) surface at room temperature is found to result in the reductive dehalogenation of the bromothienyl substituents and the subsequent formation of single strand and crosslinked coordination networks. The coordinated substrate atoms bridge the proximal thienyl groups of the organometallic intermediate, while the cleaved bromine atoms are bound on the adjacent Ag(111) surface. The intermediate complex displays a thermal lability at ˜423 K that results in the dissociation of the proximal thienyl groups with the concomitant loss of the surface bound bromine. At the thermally induced dissociation of the intermediate complex the resultant thienylporphyrin derivatives covalently couple, leading to the formation of a polymeric network of thiophene linked and meso-meso fused porphyrins.

  11. Surface-Controlled Mono/Diselective ortho C-H Bond Activation.

    Science.gov (United States)

    Li, Qing; Yang, Biao; Lin, Haiping; Aghdassi, Nabi; Miao, Kangjian; Zhang, Junjie; Zhang, Haiming; Li, Youyong; Duhm, Steffen; Fan, Jian; Chi, Lifeng

    2016-03-01

    One of the most charming and challenging topics in organic chemistry is the selective C-H bond activation. The difficulty arises not only from the relatively large bond-dissociation enthalpy, but also from the poor reaction selectivity. In this work, Au(111) and Ag(111) surfaces were used to address ortho C-H functionalization and ortho-ortho couplings of phenol derivatives. More importantly, the competition between dehydrogenation and deoxygenation drove the diversity of reaction pathways of phenols on surfaces, that is, diselective ortho C-H bond activation on Au(111) surfaces and monoselective ortho C-H bond activation on Ag(111) surfaces. The mechanism of this unprecedented phenomenon was extensively explored by scanning tunneling microscopy, density function theory, and X-ray photoelectron spectroscopy. Our findings provide new pathways for surface-assisted organic synthesis via the mono/diselective C-H bond activation. PMID:26853936

  12. Characterization of Surface Microstructures on Bio-based Polymer Film Fabricated with Nano-imprint Lithography by Synchrotron Radiation Small Angle X-ray Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Shinohara, Takamichi; Takahara, Atsushi [Graduate School of Engineering, Kyushu University, 744, Motooka, Nishi-ku Fukuoka 819-0395 (Japan); Shirahase, Tomoko; Murakami, Daiki; Hoshino, Taiki; Kikuchi, Moriya [Institute for Materials Chemistry and Engtineering, Kyushu University, 744, Motooka, Nishi-ku Fukuoka 819-0395 (Japan); Koike, Jun-ichiro; Horigome, Misao [DIC Cooperation, 631 Sakado, Sakura, Chiba 285-8688 (Japan); Masunaga, Hiroyasu; Ogawa, Hiroki, E-mail: takahara@cstf.kyushu-u.ac.jp [Japan Synchrotron Radiation Research Instiutute, Kouto, Sayo-cho, Hyogo, 679-5198 (Japan)

    2011-09-19

    Nano-imprint lithography (NIL) is a simple, low cost and high-resolution patterning method. However the precise evaluation method of nano-imprinted structure has not been established. Synchrotron radiation small angle X-ray scattering (SR-SAXS) measurement is a nondestructive and high resolution characterization method. In this study, we attempt to fabricate nanostructures on the poly(lactic acid) (PLA) film by NIL and evaluated with microscopic and scattering techniques. The mold with line/space pattern was used for NIL. Scanning electron microscope observation confirmed the formation of surface nano-structure in large areas. Also, nano-imprinted PLA film was evaluated using SR-SAXS measurement. The scattering patterns obtained from nano-imprinted PLA films were clearly observed up to higher order scattering spots. These results suggested that highly regular structure was fabricated on the surface of PLA films.

  13. Surface alloying in the Sn/Ni(111) system studied by synchrotron radiation photoelectron valence band spectroscopy and ab-initio density of states calculations

    Energy Technology Data Exchange (ETDEWEB)

    Karakalos, S.; Ladas, S. [Department of Chemical Engineering, University of Patras and FORTH/ICE-HT, POB 1414, 26504 Rion (Patras) (Greece); Janecek, P.; Sutara, F.; Nehasil, V. [Department of Electronic and Vacuum Physics, Charles University, V.Holesovickach 2, 18000 Prague 8 (Czech Republic); Tsud, N. [Sincrotrone Trieste, Strada Statale 14, km 163.5, 34012 Basovizza-Trieste (Italy); Prince, K. [Sincrotrone Trieste, Strada Statale 14, km 163.5, 34012 Basovizza-Trieste (Italy); INFM, Laboratorio TASC, in Area Science Park, Strada Statale 14, km 163.5, 34012 Basovizza-Trieste (Italy); Matolin, V. [Department of Electronic and Vacuum Physics, Charles University, V.Holesovickach 2, 18000 Prague 8 (Czech Republic); Chab, V. [Institute of Physics, Czech Academy of Sciences, Cucrovarnicka 10, 16200 Prague (Czech Republic); Papanicolaou, N.I. [Department of Physics, University of Ioannina, P.O. Box 1186, 45110 Ioannina (Greece)], E-mail: nikpap@uoi.gr; Dianat, A.; Gross, A. [Institute of Theoretical Chemistry, University of Ulm, D-89069 Ulm (Germany)

    2008-03-31

    Photoelectron spectroscopy using synchrotron radiation and ab-initio electronic structure calculations were used in order to describe the fine structure of the valence band in the Sn/Ni(111) system. The characteristic contributions of each metal in the valence band photoemission spectra obtained with a photon energy of 80 eV and their changes upon the formation of the ({radical}3 x {radical}3)R30{sup o} Sn/Ni(111) surface alloy were also born out in the calculated density-of-states curves in fair agreement with the experiments. The Sn-Ni interaction leads to a considerable broadening of the valence band width at the bimetallic surfaces.

  14. Synchrotron radiation

    International Nuclear Information System (INIS)

    This report details the activities in synchrotron radiation and related areas at Daresbury Laboratory during 1989/90. The number and scope of the scientific reports submitted by external users and in-house staff is a reflection of the large amount of scheduled beamtime and high operating efficiency achieved at the Synchrotron Radiation Source (SRS) during the past year. Over 4000 hours of user beam were available, equivalent to about 80% of the total scheduled time. Many of the reports collected here illustrate the increasing technical complexity of the experiments now being carried out at Daresbury. Provision of the appropriate technical and scientific infrastructure and support is a continuing challenge. The development of the Materials Science Laboratory together with the existing Biological Support Laboratory will extend the range of experiments which can be carried out on the SRS. This will particularly facilitate work in which the sample must be prepared or characterised immediately before or during an experiment. The year 1989/90 has also seen a substantial upgrade of several stations, especially in the area of x-ray optics. Many of the advantages of the High Brightness Lattice can only be exploited effectively with the use of focusing optics. As the performance of these stations improves, the range of experiments which are feasible on the SRS will be extended significantly. (author)

  15. A chemically inert Rashba split interface electronic structure of C60, FeOEP and PTCDA on BiAg2/Ag(111) substrates

    International Nuclear Information System (INIS)

    The fields of organic electronics and spintronics have the potential to revolutionize the electronics industry. Finding the right materials that can retain their electrical and spin properties when combined is a technological and fundamental challenge. We carry out the study of three archetypal organic molecules in intimate contact with the BiAg2 surface alloy. We show that the BiAg2 alloy is an especially suited substrate due to its inertness as support for molecular films, exhibiting an almost complete absence of substrate–molecular interactions. This is inferred from the persistence of a completely unaltered giant spin-orbit split surface state of the BiAg2 substrate, and from the absence of significant metallic screening of charged molecular levels in the organic layer. Spin-orbit split states in BiAg2 turn out to be far more robust to organic overlayers than previously thought. (paper)

  16. A chemically inert Rashba split interface electronic structure of C60, FeOEP and PTCDA on BiAg2/Ag(111) substrates

    Science.gov (United States)

    Cottin, Maren C.; Lobo-Checa, Jorge; Schaffert, Johannes; Bobisch, Christian A.; Möller, Rolf; Ortega, J. Enrique; Walter, Andrew L.

    2014-04-01

    The fields of organic electronics and spintronics have the potential to revolutionize the electronics industry. Finding the right materials that can retain their electrical and spin properties when combined is a technological and fundamental challenge. We carry out the study of three archetypal organic molecules in intimate contact with the BiAg2 surface alloy. We show that the BiAg2 alloy is an especially suited substrate due to its inertness as support for molecular films, exhibiting an almost complete absence of substrate-molecular interactions. This is inferred from the persistence of a completely unaltered giant spin-orbit split surface state of the BiAg2 substrate, and from the absence of significant metallic screening of charged molecular levels in the organic layer. Spin-orbit split states in BiAg2 turn out to be far more robust to organic overlayers than previously thought.

  17. Synchrotron radiation

    International Nuclear Information System (INIS)

    Synchrotron radiation (SR) from the bending magnet of a circular electron (positron) accelerator is a brilliant source in the vacuum ultraviolet, soft- and hard-x ray regions. First the characteristics of the bending SR are delete discussed. Though the brilliance of SR was improved dramatically in the last decade, neither bending, wiggler SR nor undulator SR is coherent. Coherent far infrared radiation in the mm wavelength region has recently been observed from a short electron bunch (∼ 2.5 mm long) in a bending magnet connected to a linac at Tohoku University. Coherent radiation due to higher harmonics generation by laser excitation of electron bunches in an undulator is then described. Finally a free electron laser (FEL) using optical klystron in a storage ring is reviewed. (author)

  18. Acceleration of electrons by a laser pulse at its output onto an optical surface of the vacuum – transparent medium interface. Laser synchrotron

    Science.gov (United States)

    Romanovskiy, M. Yu

    2016-05-01

    We consider the electron dynamics in the field of an electromagnetic wave produced at the vacuum – transparent medium interface upon reflection from the boundary, close to total internal reflection. The propagation velocity of a constant phase of the electromagnetic wave along the interface can vary from c/n to infinity (c is the speed of light in vacuum, and n is the refractive index of the medium at the interface). In this case, there emerge regions of positive and negative phases of the field with wavelengths, approximately equal to half the wavelength of the original laser beam, which can propagate at a speed close to that of light in vacuum. If a beam of relativistic electrons propagates along the surface, they can gain energy and accelerate, as well as radiate. With closed trajectories of electron motion, a laser synchrotron will be implemented as a result of many acceleration cycles.

  19. In-situ synchrotron micro-diffraction study of surface, interface, grain structure, and strain/stress evolution during Sn whisker/hillock formation

    Science.gov (United States)

    Pei, Fei; Jadhav, Nitin; Buchovecky, Eric; Bower, Allan F.; Chason, Eric; Liu, Wenjun; Tischler, Jonathan Z.; Ice, Gene E.; Xu, Ruqing

    2016-03-01

    We have performed X-ray synchrotron micro-diffraction measurements to study the processes controlling the formation of hillocks and whiskers in Sn layers on Cu. The studies were done in real-time on Sn layers that were electro-deposited immediately before the X-ray measurements were started. This enabled a region of the sample to be monitored from the as-deposited state until after a hillock feature formed. In addition to measuring the grain orientation and deviatoric strain (via Laue diffraction), the X-ray fluorescence was monitored to quantify the evolution of the Sn surface morphology and the formation of intermetallic compound (IMC) at the Sn-Cu interface. The results capture the simultaneous growth of the feature and the corresponding film stress, grain orientation, and IMC formation. The observations are compared with proposed mechanisms for whisker/hillock growth and nucleation.

  20. Lattice-Directed Formation of Covalent and Organometallic Molecular Wires by Terminal Alkynes on Ag Surfaces.

    Science.gov (United States)

    Liu, Jing; Chen, Qiwei; Xiao, Lianghong; Shang, Jian; Zhou, Xiong; Zhang, Yajie; Wang, Yongfeng; Shao, Xiang; Li, Jianlong; Chen, Wei; Xu, Guo Qin; Tang, Hao; Zhao, Dahui; Wu, Kai

    2015-06-23

    Surface reactions of 2,5-diethynyl-1,4-bis(phenylethynyl)benzene on Ag(111), Ag(110), and Ag(100) were systematically explored and scrutinized by scanning tunneling microscopy, molecular mechanics simulations, and density functional theory calculations. On Ag(111), Glaser coupling reaction became dominant, yielding one-dimensional molecular wires formed by covalent bonds. On Ag(110) and Ag(100), however, the terminal alkynes reacted with surface metal atoms, leading to one-dimensional organometallic nanostructures. Detailed experimental and theoretical analyses revealed that such a lattice dependence of the terminal alkyne reaction at surfaces originated from the matching degree between the periodicities of the produced molecular wires and the substrate lattice structures. PMID:25990647

  1. Measurement methods for surface oxides on SUS 316L in simulated light water reactor coolant environments using synchrotron XRD and XRF

    Science.gov (United States)

    Watanabe, Masashi; Yonezawa, Toshio; Shobu, Takahisa; Shoji, Tetsuo

    2013-03-01

    Synchrotron X-ray diffraction (XRD) and X-ray fluorescent (XRF) measurement techniques have been used for non-destructive characterization of surface oxide films on Type 316L austenitic stainless steels that were exposed to simulated primary water environments of pressurized water reactors (PWR) and boiling water reactors (BWR). The layer structures of the surface spinel oxides were revealed ex situ after oxidation by measurements made as a function of depth. The layer structure of spinel oxides formed in simulated PWR primary water should normally be different from that formed in simulated BWR water. After oxidation in the simulated BWR environment, the spinel oxide was observed to contain NiFe2O4 at shallow depths, and FeCr2O4 and Fe3O4 at deeper depths. By contrast, after oxidation in the simulated PWR primary water environment, a Fe3O4 type spinel was observed near the surface and FeCr2O4 type spinel near the interface with the metal substrate. Furthermore, by in situ measurements during oxidation in the simulated BWR environment, it was also demonstrated that the ratio between spinel and hematite Fe2O3 can be changed depending on the water condition such as BWR normal water chemistry or BWR hydrogen water chemistry.

  2. Measurement methods for surface oxides on SUS 316L in simulated light water reactor coolant environments using synchrotron XRD and XRF

    International Nuclear Information System (INIS)

    Highlights: ► Non-destructive characterization of surface oxide on austenitic stainless steels. ► The layer structures of surface oxides were measured by ex situ XRD and XRF. ► An autoclave was newly designed for in situ X-ray diffraction measurements. ► Instability of hematite was investigated by in situ measurements. -- Abstract: Synchrotron X-ray diffraction (XRD) and X-ray fluorescent (XRF) measurement techniques have been used for non-destructive characterization of surface oxide films on Type 316L austenitic stainless steels that were exposed to simulated primary water environments of pressurized water reactors (PWR) and boiling water reactors (BWR). The layer structures of the surface spinel oxides were revealed ex situ after oxidation by measurements made as a function of depth. The layer structure of spinel oxides formed in simulated PWR primary water should normally be different from that formed in simulated BWR water. After oxidation in the simulated BWR environment, the spinel oxide was observed to contain NiFe2O4 at shallow depths, and FeCr2O4 and Fe3O4 at deeper depths. By contrast, after oxidation in the simulated PWR primary water environment, a Fe3O4 type spinel was observed near the surface and FeCr2O4 type spinel near the interface with the metal substrate. Furthermore, by in situ measurements during oxidation in the simulated BWR environment, it was also demonstrated that the ratio between spinel and hematite Fe2O3 can be changed depending on the water condition such as BWR normal water chemistry or BWR hydrogen water chemistry

  3. Measurement methods for surface oxides on SUS 316L in simulated light water reactor coolant environments using synchrotron XRD and XRF

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, Masashi, E-mail: m-wat@fri.niche.tohoku.ac.jp [New Industry Creation Hatchery Center, Tohoku University, Sendai 980-8577 (Japan); Yonezawa, Toshio, E-mail: t-yonezawa@fri.niche.tohoku.ac.jp [New Industry Creation Hatchery Center, Tohoku University, Sendai 980-8577 (Japan); Shobu, Takahisa [Japan Atomic Energy Agency, Sayoh 679-5184 (Japan); Shoji, Tetsuo [New Industry Creation Hatchery Center, Tohoku University, Sendai 980-8577 (Japan)

    2013-03-15

    Highlights: ► Non-destructive characterization of surface oxide on austenitic stainless steels. ► The layer structures of surface oxides were measured by ex situ XRD and XRF. ► An autoclave was newly designed for in situ X-ray diffraction measurements. ► Instability of hematite was investigated by in situ measurements. -- Abstract: Synchrotron X-ray diffraction (XRD) and X-ray fluorescent (XRF) measurement techniques have been used for non-destructive characterization of surface oxide films on Type 316L austenitic stainless steels that were exposed to simulated primary water environments of pressurized water reactors (PWR) and boiling water reactors (BWR). The layer structures of the surface spinel oxides were revealed ex situ after oxidation by measurements made as a function of depth. The layer structure of spinel oxides formed in simulated PWR primary water should normally be different from that formed in simulated BWR water. After oxidation in the simulated BWR environment, the spinel oxide was observed to contain NiFe{sub 2}O{sub 4} at shallow depths, and FeCr{sub 2}O{sub 4} and Fe{sub 3}O{sub 4} at deeper depths. By contrast, after oxidation in the simulated PWR primary water environment, a Fe{sub 3}O{sub 4} type spinel was observed near the surface and FeCr{sub 2}O{sub 4} type spinel near the interface with the metal substrate. Furthermore, by in situ measurements during oxidation in the simulated BWR environment, it was also demonstrated that the ratio between spinel and hematite Fe{sub 2}O{sub 3} can be changed depending on the water condition such as BWR normal water chemistry or BWR hydrogen water chemistry.

  4. Smectic-A Order at the Surface of a Nematic Liquid Crystal: Synchrotron X-Ray Diffraction

    OpenAIRE

    Als-Nielsen, J.; Christensen, F.; Pershan, Peter S.

    1982-01-01

    A novel geometry in which it is possible to do x-ray diffraction from a horizontal surface of fluids is applied to liquid crystals. A large-diameter drop of octyloxycyanobiphenyl (8OCB) on a glass plate treated for homeotropic alignment yields perfect alignment of the smectic-A layers at the top surface over an area of several square millimeters. The surface in the bulk nematic as well as in the isotropic phase was found to consist of smectic-A layers with a penetration depth equal to the lon...

  5. Reconstruction of surface morphology from coherent scattering of 'white' synchrotron radiation in hard X-ray regime

    International Nuclear Information System (INIS)

    Energy Dispersive Reflectometry (EDR) beamline at BESSY II provides ''white'' X-rays in the useful energy range of 5< E<20 keV. In this work I measured the coherent reflectivity data at EDR bending magnet beamline at BESSY II from various surfaces. Technologically smooth wafers of semiconducting materials of Si and GaAs are used as ''trivial'' samples to determine the so called apparatus function. In addition I measured coherent reflectivity maps from thin film of highly scattering material of Pt with high atom number, Z=78 and patterned semiconducting surface like a GaAs surface grating which provides a certain periodicity in the measured scattering intensity. Finally I measured the surface speckles from a spatially confined Si wafer under the constraint that the size of the sample is smaller than the footprint of the incoming beam at the sample position. To reconstruct surface morphology from coherent reflectivity data is a typical inverse problem. Conventional phase retrieval algorithms like Gerchberg-Saxton (GS) algorithm, error reduction (ER) algorithm, hybrid input-output (HIO) algorithm are used in earlier work by other authors. I modified the conventional GS algorithm and ER algorithm which takes into account the additional Fresnel propagator term and also the illumination function at the sample position. I tested the modified algorithm successfully for a model surface in the form of a surface grating. I used the modified algorithm to reconstruct surface morphology from various static speckle measurements I performed at EDR beamline. The surface profiles reconstructed for different samples from the data at different energies (below the critical energy for the material at a particular incident angle) show almost the same roughness behavior for surface height with mean roughness of ∝1 nm. With the static speckle data I measured I could retrieve a one-dimensional picture of the sample surface with spatial resolution of ∝15 μm. The reconstruction of the

  6. The Self-Assembly of Nano-Objects Code: Applications to supramolecular organic monolayers adsorbed on metal surfaces

    CERN Document Server

    Roussel, Thomas

    2012-01-01

    The Self-Assembly of Nano-Objects (SANO) code we implemented demonstrates the ability to predict the molecular self-assembly of different structural motifs by tuning the molecular building blocks as well as the metallic substrate. It consists in a two-dimensional Grand Canonical Monte-Carlo (GCMC) approach developed to perform atomistic simulations of thousands of large organic molecules self-assembling on metal surfaces. Computing adsorption isotherms at room temperature and spanning over the characteristic sub-micrometric scales, we confront the robustness of the approach with three different well-known systems: ZnPcCl8 on Ag(111), CuPcF16 on Au(111) and PTBC on Ag(111). We retrieve respectively their square, oblique and hexagonal supramolecular tilling. The code incorporates generalized force fields to describe the molecular interactions, which provides transferability and versatility to many organic building blocks and metal surfaces.

  7. Does the Surface Matter? Hydrogen-Bonded Chain Formation of an Oxalic Amide Derivative in a Two- and Three-Dimensional Environment

    OpenAIRE

    Klappenberger, F.; Canas-Ventura, M. E.; Clair, S.; Pons, S.; Schlickum, U.; Qu, Z. R.; Strunskus, T.; Comisso, A.; Woll, C.; Brune, H.; Kern, K.; De Vita, A; Ruben, M.; Bartha, J. V.

    2008-01-01

    We report on a multi-technique investigation of the supramolecular organisation of N,N-diphenyl oxalic amide under differently dimensioned environments, namely three-dimensional (3D) in the bulk crystal, and in two dimensions on the Ag(111) surface as well as on the reconstructed Au(111) surface. With the help of Xray structure analysis and scanning tunneling microscopy (STM) we find that the molecules organize in hydrogen-bonded chains with the bonding motif qualitatively changed by the surf...

  8. Characterization of the local layer structure of a broad wall in a surface stabilized ferroelectric liquid crystal using synchrotron X-ray micro-diffraction

    International Nuclear Information System (INIS)

    The local layer structure of the broad wall of a zig-zag defect in a thin-surface stabilized ferroelectric liquid crystal cell was characterized using a synchrotron X-ray microbeam of less than 5 μm spatial resolution. By using a rocking curve measurement at the broad wall, multiple or broad peaks were observed between a pair of peaks due to a chevron structure. These new peaks are clear evidence of a modified pseudo-bookshelf structure at the wall. For 1.5 μm thick cells, a bookshelf layer is relatively flat, but is accompanied by small areas of inclined layer connecting the bookshelf and the chevron structures. For 10 μm thick cells, the pseudo-bookshelf structure bends or undulates both perpendicular and parallel to the rubbing direction. No appreciable change in the layer spacing was observed in the modified pseudo-bookshelf structure. The temperature dependence of the broad wall layer structure was also measured. (author)

  9. Physical and Chemical Properties of Ce₁-xZrxO₂ Nanoparticles and Ce₁-xZrxO₂ (111) Surfaces: Synchrotron-based Studies

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, J A.; Wang, X; Liu, Gang; Hanson, Jonathan; Hrbek, Jan; Peden, Charles HF.; Iglesias-Juez, A; Fernández-García, M

    2005-03-16

    In this article, we review a series of studies that use synchrotron-based techniques (high-resolution photoemission, time-resolved x-ray diffraction, and x-ray absorption near-edge spectroscopy) to investigate the physical and chemical properties of Ce?-xZrxO? nanoparticles and Ce?-xZrxO? (111) surfaces (x ? 0.5). Ce O? and Ce?-xZrxO? particles in sizes between 3 and 7 nm were synthesized using a novel microemulsion method. The results of XANES (O K-edge, Ce and Zr LIII-edges) indicate that the Ce?-xZrxO? nanoparticles and Ce?-xZrxO? (111) surfaces have very similar electronic properties. For these systems, the lattice constant decreased with increasing Zr content, varying from 5.40 ? in CeO? to 5.27 ? in Ce???Zr???O?. Within the fluorite structure, the Zr atoms exhibited structural perturbations that led to different types of Zr-O distances and non-equivalent O atoms in the Ce?-xZrxO? compounds. The Ce?-xZrxO? nanoparticles were more reactive towards H? and SO? than the Ce?-xZrxO? (111) surfaces. The Ce?-xZrxO? (111) surfaces did not reduce in hydrogen at 300 C. At temperatures above 250 C, the Ce?-xZrxO? nanoparticles reacted with H? and water evolved into gas phase. XANES showed the generation of Ce??cations without reduction of Zr??. There was an expansion in the unit cell of the reduced nanoparticles probably as a consequence of a partial Ce??? Ce?? transformation and the sorption of hydrogen into the bulk of the material. S K-edge XANES spectra pointed to SO? as the main product of the adsorption of SO? on the Ce?-xZrxO? nanoparticles and Ce?-xZrxO? (111) surfaces. Full dissociation of SO? was seen on the nanoparticles but not on the Ce?-xZrxO? (111) surfaces. The metal cations at corner and edge sites of the Ce?-xZrxO? nanoparticles probably play a very important role in interactions with the H? and SO? molecules.

  10. Synchrotron radiation - Applications in the earth sciences

    Science.gov (United States)

    Bassett, W. A.; Brown, G. E., Jr.

    Synchrotron-radiation sources and their characteristics are overviewed along with recent synchrotron-based research on earth materials and future earth-science applications utilizing the next generation of synchrotron-radiation sources presently under construction. Focus is placed on X-ray scattering studies of earth materials (crystalline and noncrystalline) under ambient conditions, diffraction studies of earth materials at high pressures and/or temperatures, spectroscopic studies, primarily X-ray absorption spectroscopy, and spatially resolved X-ray fluorescence studies of compositional variations in earth materials. It is noted that other synchrotron-based methods, such as X-ray tomography and topography may become important in characterizing earth materials, while soft X-ray/vacuum ultraviolet radiation from synchrotron sources can be applied to problems involving the structural environments of low-atomic-number elements and the characterization of surface reactions of minerals with liquids and gases.

  11. Magnetism of 3d transition metal nanoparticles on surfaces probed with synchrotron radiation - from ensembles towards individual objects

    Energy Technology Data Exchange (ETDEWEB)

    Bansmann, Joachim [Institut fuer Oberflaechenchemie und Katalyse, Universitaet Ulm (Germany); Kleibert, Armin [Institut fuer Physik, Universitaet Rostock (Germany); Swiss Light Source, Paul Scherrer Institut, Villigen (Switzerland); Getzlaff, Mathias [Institut fuer Angewandte Physik, Universitaet Duesseldorf (Germany); Rodriguez, Arantxa Fraile; Nolting, Frithjof [Swiss Light Source, Paul Scherrer Institut, Villigen (Switzerland); Boeglin, Christine [Institut de Physique et de Chimie de Strasbourg, Universite de Strasbourg (France); Meiwes-Broer, Karl-Heinz [Institut fuer Physik, Universitaet Rostock (Germany)

    2010-05-15

    Mass-filtered Fe, Co and FeCo nanoparticles in the size regime from 7 to 25 nm have been deposited under soft-landing conditions onto ferromagnetic films, non-magnetic surfaces as well as embedded into Al matrices. In situ X-ray magnetic circular dichroism (XMCD) measurements reveal a ferromagnetic behaviour of FeCo nanoparticles (size: 10 nm) on Si-substrates at room temperature whereas the respective Co nanoparticles are superparamagnetic. Besides measurements on ensembles of nanoparticles, we have also carried out in situ measurements on individual Fe nanoparticles using X-ray photoemission electron microscopy at the Fe L{sub 3,2} edges. Fe nanoparticles on Co films show a magnetic contrast depending on the direction of the underlying poly-crystalline Co domains. This technique also allows to record XMCD spectra on individual nanoparticles. Spectroscopy and spectro-microscopy on magnetic particles. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  12. Switching orientation of adsorbed molecules: Reverse domino on a metal surface

    Science.gov (United States)

    Braatz, C. R.; Esat, T.; Wagner, C.; Temirov, R.; Tautz, F. S.; Jakob, P.

    2016-01-01

    A thus far unknown phase of 1,4,5,8-naphthalene-tetracarboxylic dianhydride (NTCDA) on Ag(111), characterized by an all perpendicular orientation of the planar molecules and bound to the Ag substrate through the carboxyl oxygen atoms has been identified using infrared absorption spectroscopy and scanning tunneling microscopy. Its formation process requires second layer NTCDA to squeeze into empty spaces between relaxed monolayer NTCDA molecules. Remarkably, this process causes initially parallel oriented NTCDA to likewise adopt the new, highly inclined adsorption geometry. According to our SPA-LEED and STM findings, the new phase displays a distinct long range order and shows a pronounced tendency to form 1D rows or narrow islands. We suggest that extra NTCDA preferentially transforms into the upright configuration close to existing islands and attaches to them, i.e. the transformation process proceeds in a directed and recurrent manner (reverse domino scenario). Identical processing starting with a compressed NTCDA/Ag(111) monolayer leads to a purely parallel oriented bilayer, that is, the NTCDA monolayer phase is retained and merely acts as a passive template for bilayer NTCDA. The new vertical NTCDA phase represents an unusual molecular system with π-orbitals oriented parallel to a metal surface. A substantially reduced coupling of these orbitals to Ag(111) electronic levels is conjectured, which will have a major impact on intermolecular couplings and electronically excited state lifetimes.

  13. CO Chemisorption at Metal Surfaces and Overlayers

    DEFF Research Database (Denmark)

    Hammer, Bjørk; Morikawa, Y.; Nørskov, Jens Kehlet

    1996-01-01

    A database of ab initio calculations of the chemisorption energy of CO over Ni(111), Cu(111), Ru(0001), Pd(111), Ag(111), Pt(111), Au(111), Cu3Pt(111), and some metallic overlayer structures is presented. The trends can be reproduced with a simple model describing the interaction between the metal...... d states and the CO 2 pi* and 5 sigma states, renormalized by the metal sp continuum. Our model rationalizes the results by Rodriguez and Goodman [Science 257, 897 (1992)] showing a strong correlation between the CO chemisorption energy and the surface core level shift....

  14. Role of intermolecular interactions on the electronic and geometric structure of a large Pi-conjugated molecule adsorbed on a metal surface

    OpenAIRE

    Kilian, L.; Hauschild, A.; Temirov, R.; Soubatch, S.; Schoell, A.; Bendounan, A.; Reinert, F.; Lee, T. L.; Tautz, F. S.; Sokolowski, M.; Umbach, E

    2008-01-01

    The organic semiconductor molecule 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA) exhibits two adsorption states on the Ag(111) surface: one in a metastable disordered phase, prepared at low temperatures, the other in the long-range ordered monolayer phase obtained at room temperature. Notably, the two states differ substantial in their vertical bonding distances, intramolecular distortions, and electronic structures. The difference is explained by intermolecular interactions, which ar...

  15. Synchrotron radiation facilities

    CERN Multimedia

    1972-01-01

    Particularly in the past few years, interest in using the synchrotron radiation emanating from high energy, circular electron machines has grown considerably. In our February issue we included an article on the synchrotron radiation facility at Frascati. This month we are spreading the net wider — saying something about the properties of the radiation, listing the centres where synchrotron radiation facilities exist, adding a brief description of three of them and mentioning areas of physics in which the facilities are used.

  16. Synchrotron radiation: science & applications

    OpenAIRE

    Aranda, Miguel A. G.

    2015-01-01

    This general talk is devoted to briefly introduce the main uses and applications of synchrotron radiation. An initial introduction will be dedicated to describe a synchrotron as a Large Facility devoted to produce photons that will be used to carry out excellent science. The five outstanding main characteristics of synchrotron radiation are: i) High brilliance and collimation ii) Wavelength tunability iii) Beamsize tunability iv) Defined polarization v) Time structure vi)...

  17. A medical proton synchrotron

    International Nuclear Information System (INIS)

    A special medical weak-focusing synchrotron using only wedge focusing at dipole ends, is proposed to make a proton cancer therapy. A new method of the turn number calculation in a proton synchrotron allowing to calculate the energy gain per turn, is formulated. 13 refs.; 10 figs.; 1 tab

  18. Synchrotron radiation from protons

    Energy Technology Data Exchange (ETDEWEB)

    Dutt, S.K.

    1992-12-01

    Synchrotron radiation from protons, though described by the same equations as the radiation from electrons, exhibits a number of interesting features on account of the parameters reached in praxis. In this presentation, we shall point out some of the features relating to (i) normal synchrotron radiation from dipoles in proton machines such as the High Energy Booster and the Superconducting Super Collider; (ii) synchrotron radiation from short dipoles, and its application to light monitors for proton machines, and (iii) synchrotron radiation from undulators in the limit when, the deflection parameter is much smaller than unity. The material for this presentation is taken largely from the work of Hofmann, Coisson, Bossart, and their collaborators, and from a paper by Kim. We shall emphasize the qualitative aspects of synchrotron radiation in the cases mentioned above, making, when possible, simple arguments for estimating the spectral and angular properties of the radiation. Detailed analyses can be found in the literature.

  19. Synchrotron characterization of functional tin dioxide nanowires

    International Nuclear Information System (INIS)

    Wire-like crystals of tin dioxide were synthesized by a gas-transport technique. The wires, of mainly nanometric diameters, were characterized by spectroscopy and microscopy techniques with the use of highly brilliant and intense synchrotron radiation. We studied the influence of the surface chemical state and the oxygen vacancies on the atomic and electronic structure of the nanowires. The surface of the nanowires is covered by a few nanometers of tin suboxides. The lack of oxygen over the surface layers leads to specific sub-zone formation in a gap, as shown by synchrotron studies

  20. Synchrotron characterization of functional tin dioxide nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Domashevskaya, E. P., E-mail: ftt@phys.vsu.ru; Chuvenkova, O. A.; Turishchev, S. Yu. [Voronezh State University, Voronezh (Russian Federation)

    2015-12-31

    Wire-like crystals of tin dioxide were synthesized by a gas-transport technique. The wires, of mainly nanometric diameters, were characterized by spectroscopy and microscopy techniques with the use of highly brilliant and intense synchrotron radiation. We studied the influence of the surface chemical state and the oxygen vacancies on the atomic and electronic structure of the nanowires. The surface of the nanowires is covered by a few nanometers of tin suboxides. The lack of oxygen over the surface layers leads to specific sub-zone formation in a gap, as shown by synchrotron studies.

  1. Grazing incidence synchrotron radiation optics: correlation of performance with metrology

    International Nuclear Information System (INIS)

    Image distortions produced by a cylinder mirror at the National Synchrotron Light Source are compared with performance predictions based on measurements of surface slope errors in the millimeter spatial period regime made with an optical surface profiler

  2. Metrology of reflection optics for synchrotron radiation

    International Nuclear Information System (INIS)

    Recent years have seen an almost explosive growth in the number of beam lines on new and existing synchrotron radiation facilities throughout the world. The need for optical components to utilize the unique characteristics of synchrotron radiation has increased accordingly. Unfortunately, the technology to manufacture and measure the large, smooth, exotic optical surfaces required to focus and steer the synchrotron radiation beam has not progressed as rapidly as the operational demands on these components. Most companies do not wish to become involved with a project that requires producing a single, very expensive, aspheric optic with surface roughness and figure tolerances that are beyond their capabilities to measure. This paper will review some of the experiences of the National Synchrotron Light Source in procuring grazing incidence optical components over the past several years. We will review the specification process - how it is related to the function of the optic, and how it relates to the metrology available during the manufacturing process and after delivery to the user's laboratory. We will also discuss practical aspects of our experience with new technologies, such as single point diamond turning of metal mirrors and the use of SiC as a mirror material. Recent advances in metrology instrumentation have the potential to move the measurement of surface figure and finish from the research laboratory into the optical shop, which should stimulate growth and interest in the manufacturing of optics to meet the needs of the synchrotron radiation user community

  3. National Synchrotron Light Source

    International Nuclear Information System (INIS)

    This report discussion research being conducted at the National Synchrotron light source. In particular, this report contains operations summaries; symposia, workshops, and projects; NSLS highlights; and abstracts of science at the NSLS

  4. The Australian synchrotron project

    International Nuclear Information System (INIS)

    Full text: The Australian Synchrotron to be built at Monash University, is a synchrotron light facility based on a 3-GeV electron storage ring. It is scheduled to be fully operational in 2007. In this paper we describe the accelerator systems that lie at the heart of the facility, and describe the spectral characteristics of the 'light' - ranging from infra-red to hard x-rays - that will be provided from bend magnets, undulators, and wigglers

  5. RF gymnastics in synchrotrons

    OpenAIRE

    Garoby, R.

    2011-01-01

    The RF systems installed in synchrotrons can be used to change the longitudinal beam characteristics. 'RF gymnastics' designates manipulations of the RF parameters aimed at providing such non-trivial changes. Some keep the number of bunches constant while changing bunch length, energy spread, emittance, or distance between bunches. Others are used to change the number of bunches. After recalling the basics of longitudinal beam dynamics in a hadron synchrotron, this paper deals with the most c...

  6. In situ synchrotron X-ray diffraction study of surface scale formation during CO2 corrosion of carbon steel at temperatures up to 90 oC

    International Nuclear Information System (INIS)

    In situ synchrotron X-ray diffraction was used to follow the formation of corrosion product scales on carbon steel in CO2 saturated brine at temperatures from 40 to 90 oC. The corrosion process was accelerated by applying a small anodic current, and in selected tests a scale inhibitor, amino trimethylene phosphonic acid (ATMPA), was added. Siderite was identified as the major phase in the scale formed in all conditions. With increasing temperature, the scale formation rate increased, while the scale thickness and crystallite size decreased. Above 60 oC, the scale became increasingly protective. The scale thickness and crystallite size decreased with increasing ATMPA concentration.

  7. Growth of n-alkane films on a single-crystal substrate

    DEFF Research Database (Denmark)

    Wu, Z. U.; Ehrlich, S. N.; Matthies, B.; Herwig, K. W.; Dai, P.; Volkmann, U. G.; Hansen, Flemming Yssing; Taub, H.

    The structure and growth mode of alkane films (n-C/sub n/H/sub 2n+2/; n=4, 6, 7) adsorbed on a Ag(111) surface have been investigated by synchrotron X-ray scattering. New models are proposed for the butane (n=4) and hexane (n=6) monolayer and butane bilayer structures. Specular reflectivity scans...

  8. Growth of n-alkane films on a single-crystal substrate

    DEFF Research Database (Denmark)

    Wu, Z. U.; Ehrlich, S. N.; Matthies, B.;

    2001-01-01

    The structure and growth mode of alkane films (n-C/sub n/H/sub 2n+2/; n=4, 6, 7) adsorbed on a Ag(111) surface have been investigated by synchrotron X-ray scattering. New models are proposed for the butane (n=4) and hexane (n=6) monolayer and butane bilayer structures. Specular reflectivity scans...

  9. Some application of synchrotron radiation

    International Nuclear Information System (INIS)

    Continuous tuneable wavelength in the range 0.01A < λ < 100A, high brilliance and parallelity of the beam are the outstanding properties for all applications of synchrotron radiation in condensed matter research. High angular and time resolution in synchrotron X-ray diffraction may be achieved. Powder Diffraction pattern with a full width at half maximum (FWHM) of Bragg reflections of ΔΘ - 0.02 display a resolution about five times better than laboratory equipment. Thus the investigation of structural phase transitions with only minor metric changes are feasible as well as direct determination of crystal structures from powder data. Registration of complete powder patterns in a few milliseconds opens the road to kinetic studies of crystallisation from glasses or melt and to structural phase transitions. The information from diffraction experiments which provide information on long range order is related to X-ray absorption experiments (XANES and EXAFS). X-ray absorption will provide information on the local environment of atoms (EXAFS) or on its electronic nature. Texture, strain and stress investigations with synchrotron radiation offer advantages as compared to laboratory X-ray work. The angular resolution is considerably improved due to the parallel beam geometry and the small beam size and the penetration depth may be varied by a factor of 6. Thus not only general orientation distribution functions but the anisotropy strain and complex stress behaviour at surfaces may be investigated in particular grains. Furthermore all kinds of surface studies at grazing incidence are performed with considerable advantage. (orig.)

  10. Future Synchrotron Radiation Sources

    CERN Document Server

    Winick, Herman

    2003-01-01

    Sources of synchrotron radiation (also called synchrotron light) and their associated research facilities have experienced a spectacular growth in number, performance, and breadth of application in the past two to three decades. In 1978 there were eleven electron storage rings used as light sources. Three of these were small rings, all below 500 mega-electron volts (MeV), dedicated to this purpose; the others, with energy up to 5 giga-electron volts (GeV), were used parasitically during the operation of the ring for high energy physics research. In addition, at that time synchrotron radiation from nine cyclic electron synchrotrons, with energy up to 5 GeV, was also used parasitically. At present no cyclic synchrotrons are used, while about 50 electron storage rings are in operation around the world as fully dedicated light sources for basic and applied research in a wide variety of fields. Among these fields are structural molecular biology, molecular environmental science, materials, analytic chemistry, micr...

  11. Delocalized π state between molecules through a surface confined pseudodihydrogen bond.

    Science.gov (United States)

    Chen, Lan; Li, Hui; Wee, Andrew Thye Shen

    2010-11-26

    When 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA) and coronene molecules coadsorb on the Ag(111) surface, one-dimensional PTCDA molecular oligomers with efficient electronic connection via noncovalent bonds are observed by low temperature scanning tunneling microscopy. Density functional theory calculations indicate the neighboring PTCDA molecules form oligomers due to strong PTCDA-metal interactions, which result in overlapping of π orbitals and pseudodihydrogen surface bonds between molecules. Our results provide a potential approach for electron transport from molecule to molecule directly through noncovalent bond. PMID:21231400

  12. Spin-orbit splitting of the Shockley surface state on Cu(111)

    Science.gov (United States)

    Tamai, A.; Meevasana, W.; King, P. D. C.; Nicholson, C. W.; de la Torre, A.; Rozbicki, E.; Baumberger, F.

    2013-02-01

    We present angle-resolved photoemission data from Cu(111). Using a focused 6 eV continuous-wave laser for photoexcitation, we achieve a high effective momentum resolution, enabling detection of the Rashba spin splitting in the Shockley surface state on Cu(111). The magnitude of the spin splitting of Δk˜0.006 Å-1 is surprisingly large and exceeds values predicted for the analogous surface state on Ag(111), but is reproduced by first-principles calculations. We further resolve a kink in the dispersion, which we attribute to electron-phonon coupling.

  13. RF gymnastics in synchrotrons

    CERN Document Server

    Garoby, R

    2011-01-01

    The RF systems installed in synchrotrons can be used to change the longitudinal beam characteristics. 'RF gymnastics' designates manipulations of the RF parameters aimed at providing such non-trivial changes. Some keep the number of bunches constant while changing bunch length, energy spread, emittance, or distance between bunches. Others are used to change the number of bunches. After recalling the basics of longitudinal beam dynamics in a hadron synchrotron, this paper deals with the most commonly used gymnastics. Their principle is described as well as their performance and limitations.

  14. RF Gymnastics in Synchrotrons

    CERN Document Server

    Garoby, R

    2005-01-01

    The RF systems installed in synchrotrons can be used to change the longitudinal beam characteristics. "RF gymnastics" designates manipulations of the RF parameters aimed at providing such non-trivial changes. Some keep the number of bunches constant while changing bunch length, energy spread, emittance or distance between bunches. Others are used to change the number of bunches. After recalling the basics of longitudinal beam dynamics in a hadron synchrotron, this paper deals with the most commonly used gymnastics. Their principle is described as well as their performance and limitations.

  15. Chemical applications of synchrotron radiation: Workshop report

    International Nuclear Information System (INIS)

    The most recent in a series of topical meetings for Advanced Photon Source user subgroups, the Workshop on Chemical Applications of Synchrotron Radiation (held at Argonne National Laboratory, October 3-4, 1988) dealt with surfaces and kinetics, spectroscopy, small-angle scattering, diffraction, and topography and imaging. The primary objectives were to provide an educational resource for the chemistry community on the scientific research being conducted at existing synchrotron sources and to indicate some of the unique opportunities that will be made available with the Advanced Photon Source. The workshop organizers were also interested in gauging the interest of chemists in the field of synchrotron radiation. Interest expressed at the meeting has led to initial steps toward formation of a Chemistry Users Group at the APS. Individual projects are processed separately for the data bases

  16. Chemical applications of synchrotron radiation: Workshop report

    Energy Technology Data Exchange (ETDEWEB)

    1989-04-01

    The most recent in a series of topical meetings for Advanced Photon Source user subgroups, the Workshop on Chemical Applications of Synchrotron Radiation (held at Argonne National Laboratory, October 3-4, 1988) dealt with surfaces and kinetics, spectroscopy, small-angle scattering, diffraction, and topography and imaging. The primary objectives were to provide an educational resource for the chemistry community on the scientific research being conducted at existing synchrotron sources and to indicate some of the unique opportunities that will be made available with the Advanced Photon Source. The workshop organizers were also interested in gauging the interest of chemists in the field of synchrotron radiation. Interest expressed at the meeting has led to initial steps toward formation of a Chemistry Users Group at the APS. Individual projects are processed separately for the data bases.

  17. Third-generation synchrotron light sources

    International Nuclear Information System (INIS)

    X rays are a powerful probe of matter because they interact with electrons in atoms, molecules, and solids. They are commonly produced by relativistic electrons or positrons stored in a synchrotron. Recent advances in technology are leading to the development of a new third generation of synchrotron radiation sources that produce vacuum-ultraviolet and x-ray beams of unprecedented brightness. These new sources are characterized by a very low electron-beam emittance and by long straight sections to accommodate permanent-magnet undulators and wigglers. Several new low-energy light sources, including the Advanced Light Source, presently under construction at the Lawrence Berkeley Laboratory, and ELETTRA, presently being constructed in Trieste, will deliver the world's brightest synchrotron radiation in the VUV and soft x-ray regions of the spectrum. Applications include atomic and molecular physics and chemistry, surface and materials science, microscopy, and life sciences

  18. CORNELL: Synchrotron 25

    International Nuclear Information System (INIS)

    A recent celebration marked the twenty-fifth anniversary of the Cornell Electron Synchrotron. The major milestone in the commissioning of the synchrotron was on October 11, 1967 when Helen Edwards, Boyce McDaniel, and Maury Tigner achieved a 7 GeV beam, a worldrecord energy for electron synchrotrons at that time. Like so many advances in experimental physics, this occurred early in the morning - 3 a.m.! The transition from accelerator commissioning to high energy physics operation was extremely rapid; 7 GeV operation for data collection was routine just five weeks later. Throughout its life as a source of photon and electron beams for fixed target experiments, the synchrotron maintained energy leadership for circular electron machines. Originally designed for operation at 10 GeV, eventually it consistently provided beams for experiments at energies up to 11.6 GeV. It now operates at 5 GeV, serving as the injector for the CESR electron-positron storage ring. Robert Wilson was director of the laboratory during the design and most of the construction of the machine. He left near the end of the construction to become the first director of Fermilab and was replaced by Boyce McDaniel, who guided the laboratory from the completion of the synchrotron to the construction and early operation of CESR. Wilson recalled how the laboratory had originally proposed a 3 GeV turnkey machine to be built entirely by industry and would fit in the space previously occupied by earlier Cornell accelerators. However, members of the laboratory realized that 3 GeV would not open new physics frontiers, that the construction of the accelerator was much of the fun of doing high energy physics experiments, and that a more challenging project was needed. This led to the proposal for the 10 GeV synchrotron which was built in the ''Cornell Style'' with many of the components fabricated and nearly all of the assembly done at Cornell

  19. Brazilian Synchrotron Radiation Project

    International Nuclear Information System (INIS)

    The proposal for a Brazilian national laboratory for synchrotron radiation is presented. The first design study led to a system consisting of a LINAC, an injection ring and a low emittance storage ring. The main ring is designed to be upgraded to 3GeV with an emittance of 4 x 10-8 rad.m. The design study also indicated the possibility of using the injection ring as a soft x-Rays/VUV source

  20. Engineering application of synchrotron radiation

    International Nuclear Information System (INIS)

    The synchrotron radiation which is generated when the circular motion of fast electrons is carried out in vacuum has been studied as the source of X-ray and ultraviolet ray for physical property research, but recently attention has been paid to its industrial application. In this report, from the viewpoint of how to utilize the properties of synchrotron radiation to electronic industries, the recent trend of research is explained. Synchrotron radiation is the electromagnetic waves radiated in the tangential direction to their track when the electrons at the velocity close to light velocity carry out acceleration motion. The synchrotron radiation generator is an electron storage ring. Synchrotron radiation is the beam having good parallelism, concentrating in the orbit plane of electrons, and is led to respective experimental devices with beam lines. Synchrotron radiation lithography has become the start of its industrial application. The process technology being excited by synchrotron radiation, the evaluation of materials using synchrotron radiation, small synchrotron radiation generators and the new sources of light are reported. Synchrotron radiation is the important technological field developed by the joint work of physics and engineering in the latter half of 20th century, following semiconductors, lasers and superconductivity. (K.I.)

  1. Longitudinal emittance control in high intensity proton synchrotrons

    International Nuclear Information System (INIS)

    Experiments of synchrotron injection using the direct fast chopped H- beam extracted from a surface-plasma-type H- ion source has been successfully achieved. The injection phase of the fast chopped beam from linac into the booster synchrotron is adjustable to the center of rf bucket by using this beam. It was obtained that the longitudinal emittance was controlled at the extraction of the booster synchrotron, and that the beam loss during the injection into main ring of the KEK-PS was reduced by this fast chopped beam. (author)

  2. Materials science and technology by synchrotron radiation

    International Nuclear Information System (INIS)

    In the present paper, features of the Photon Factory, a facility for synchrotron research installed at the National Laboratory for High Energy Physics in Japan, are outlined, and then the impact of the advent of synchrotron radiation is discussed in relation to its outcome during the past seven years. Prospects for future development of synchrotron radiation are also presented. The facility consists of an injector linac to accelerate electrons up to 2.5 GeV and a ring to store the accelerated electrons in a closed orbit. In the Photon Factory, a 400m-long linac has been constructed for use as injector for both the Photon Factory and the TRISTAN electron-positron collider. The storage ring is operated at the same electron energy of 2.5 GeV. The present report also describes some applications of synchrotron radiation, focusing on spectroscopy (X-ray fluorescence technique and time-resolved X-ray absorption spectroscopy), diffraction and scattering (surface structure studies and protein crystallography), and photo-chemical processing. (N.K.)

  3. Reconstruction of surface morphology from coherent scattering of ''white'' synchrotron radiation in hard X-ray regime

    Energy Technology Data Exchange (ETDEWEB)

    Sant, Tushar

    2009-07-01

    Energy Dispersive Reflectometry (EDR) beamline at BESSY II provides ''white'' X-rays in the useful energy range of 5surfaces. Technologically smooth wafers of semiconducting materials of Si and GaAs are used as ''trivial'' samples to determine the so called apparatus function. In addition I measured coherent reflectivity maps from thin film of highly scattering material of Pt with high atom number, Z=78 and patterned semiconducting surface like a GaAs surface grating which provides a certain periodicity in the measured scattering intensity. Finally I measured the surface speckles from a spatially confined Si wafer under the constraint that the size of the sample is smaller than the footprint of the incoming beam at the sample position. To reconstruct surface morphology from coherent reflectivity data is a typical inverse problem. Conventional phase retrieval algorithms like Gerchberg-Saxton (GS) algorithm, error reduction (ER) algorithm, hybrid input-output (HIO) algorithm are used in earlier work by other authors. I modified the conventional GS algorithm and ER algorithm which takes into account the additional Fresnel propagator term and also the illumination function at the sample position. I tested the modified algorithm successfully for a model surface in the form of a surface grating. I used the modified algorithm to reconstruct surface morphology from various static speckle measurements I performed at EDR beamline. The surface profiles reconstructed for different samples from the data at different energies (below the critical energy for the material at a particular incident angle) show almost the same roughness behavior for surface height with mean roughness of {proportional_to}1 nm. With the static speckle data I measured I could retrieve a one-dimensional picture of the sample surface with spatial

  4. Selective surface functionalization of polystyrene induced by synchrotron or UV radiation in the presence of oxygen or acrylic acid vapors; Funcionalizacao superficial seletiva de poliestireno induzida por radiacao sincrotron ou ultravioleta

    Energy Technology Data Exchange (ETDEWEB)

    Kessler, Felipe; Kuhn, Sidiney; Weibel, Daniel E., E-mail: felipekessler@gmail.co [Universidade Federal do Rio Grande do Sul (IQ/UFRGS), Porto Alegre, RS (Brazil) Inst. de Quimica. Dept. de Fisico-Quimica

    2009-07-01

    Efficient surface functionalization of Polystyrene (PS) thin films by electromagnetic radiation in combination with a reactive gaseous atmosphere was obtained. Monochromatic synchrotron (SR) or polychromatic UV radiation were used as excitation sources. When SR was used, O{sub 2} was introduced after irradiation into the UHV chamber. UV irradiation was carried out keeping a constant flow of O{sub 2} or acrylic acid (AA) vapors during the photolysis. FTIR-ATR and XPS-NEXAFS spectra were obtained at the UFRGS and the LNLS, Campinas respectively. PS films were functionalized by monochromatic SR and then expose to O{sub 2} at specific transitions such us C 1s {yields}{sigma}{sup *}{sub C-C} excitation. It was found a high rate of COO, C=O and C-O groups at the surface (> 70%). UV-assisted treatment in the presence of AA vapors showed that an efficient polymerization process took place, such as, it was observed in previous AA low pressure RF plasma treatments. UV-assisted functionalization has the advantage of lower costs and simple set-up compared to plasma treatments. (author)

  5. Synchrotron Radiation as CMB Foreground

    OpenAIRE

    Smoot, George F.

    1999-01-01

    Synchrotron emission is an important process in Galactic dynamics and a potentially confusing foreground for cosmic microwave background (CMB) radiation observations. Though the mechanism of synchrotron emission is well understood, the details for the Galaxy and many external sources are not well characterized. Quality maps at multiple frequencies are lacking but needed for a full understanding of the Galactic synchrotron emission, including intensity, spectrum, and spectral variation. At hig...

  6. Synchrotron-based XPS studies of AlGaN and GaN surface chemistry and its relationship to ion sensor behaviour

    International Nuclear Information System (INIS)

    Highlights: • Soft X-ray was used to study the surface chemistry of GaN and AlGaN. • The surface chemistry and sensor behaviour were investigated. • The oxide of aluminum is significantly more reactive than gallium. • The Cl− ions are greater in GaN samples compared to AlGaN samples. - Abstract: Soft X-ray photoelectron spectroscopy was used to investigate the fundamental surface chemistry of both AlGaN and GaN surfaces in the context of understanding the behaviour of AlGaN/GaN heterostructures as chemical field-effect transistor (CHEMFET) ion sensors. AlGaN and GaN samples were subjected to different methods of oxide growth (native oxide and thermally grown oxide) and chemical treatment conditions. Our investigations indicate that the etching of the oxide layer is more pronounced with AlGaN compared to GaN. Also, we observed that chloride ions have a greater tendency to attach to the GaN surface relative to the AlGaN surface. Furthermore, chloride ions are comparatively more prevalent on surfaces treated with 5% HCl acid solution. The concentration of chloride ions is even higher on the HCl treated native oxide surface resulting in a very clear deconvolution of the Cl 2p1/2 and Cl 2p3/2 peaks. For GaN and AlGaN surfaces, a linear response (e.g. source-drain current) is typically seen with variation in pH of buffered solutions with constant reference electrode voltage at the surface gate; however, an inverted bath-tub type response (e.g. a maximum at neutral pH and lower values at pH values away from neutral) and a general tendency to negative charge selectivity has been also widely reported. We have shown that our XPS investigations are consistent with the different sensor response reported in the literature for these CHEMFET devices and may help to explain the differing response of these materials

  7. Synchrotron-based XPS studies of AlGaN and GaN surface chemistry and its relationship to ion sensor behaviour

    Energy Technology Data Exchange (ETDEWEB)

    Khir, Farah Liyana Muhammad, E-mail: 21001899@student.uwa.edu.au [School of Electrical, Electronic and Computer Engineering, The University of Western Australia, 35 Stirling Hwy., Crawley, Western Australia 6009 (Australia); Myers, Matthew, E-mail: Matt.Myers@csiro.au [School of Chemistry and Biochemistry, The University of Western Australia, 35 Stirling Hwy., Crawley, Western Australia 6009 (Australia); CSIRO Earth Science and Resource Engineering, Kensington, Western Australia 6151 (Australia); Podolska, Anna [School of Electrical, Electronic and Computer Engineering, The University of Western Australia, 35 Stirling Hwy., Crawley, Western Australia 6009 (Australia); Department of Exploration Geophysics, Curtin University of Technology, 26 Dick Perry Avenue, ARRC, Kensington, Western Australia 6151 (Australia); Sanders, Tarun Maruthi [School of Electrical, Electronic and Computer Engineering, The University of Western Australia, 35 Stirling Hwy., Crawley, Western Australia 6009 (Australia); Baker, Murray V., E-mail: murray.baker@uwa.edu.au [School of Chemistry and Biochemistry, The University of Western Australia, 35 Stirling Hwy., Crawley, Western Australia 6009 (Australia); Nener, Brett D., E-mail: brett.nener@uwa.edu.au [School of Electrical, Electronic and Computer Engineering, The University of Western Australia, 35 Stirling Hwy., Crawley, Western Australia 6009 (Australia); Parish, Giacinta, E-mail: giacinta.parish@uwa.edu.au [School of Electrical, Electronic and Computer Engineering, The University of Western Australia, 35 Stirling Hwy., Crawley, Western Australia 6009 (Australia)

    2014-09-30

    Highlights: • Soft X-ray was used to study the surface chemistry of GaN and AlGaN. • The surface chemistry and sensor behaviour were investigated. • The oxide of aluminum is significantly more reactive than gallium. • The Cl{sup −} ions are greater in GaN samples compared to AlGaN samples. - Abstract: Soft X-ray photoelectron spectroscopy was used to investigate the fundamental surface chemistry of both AlGaN and GaN surfaces in the context of understanding the behaviour of AlGaN/GaN heterostructures as chemical field-effect transistor (CHEMFET) ion sensors. AlGaN and GaN samples were subjected to different methods of oxide growth (native oxide and thermally grown oxide) and chemical treatment conditions. Our investigations indicate that the etching of the oxide layer is more pronounced with AlGaN compared to GaN. Also, we observed that chloride ions have a greater tendency to attach to the GaN surface relative to the AlGaN surface. Furthermore, chloride ions are comparatively more prevalent on surfaces treated with 5% HCl acid solution. The concentration of chloride ions is even higher on the HCl treated native oxide surface resulting in a very clear deconvolution of the Cl 2p{sub 1/2} and Cl 2p{sub 3/2} peaks. For GaN and AlGaN surfaces, a linear response (e.g. source-drain current) is typically seen with variation in pH of buffered solutions with constant reference electrode voltage at the surface gate; however, an inverted bath-tub type response (e.g. a maximum at neutral pH and lower values at pH values away from neutral) and a general tendency to negative charge selectivity has been also widely reported. We have shown that our XPS investigations are consistent with the different sensor response reported in the literature for these CHEMFET devices and may help to explain the differing response of these materials.

  8. Synchrotron Radiation as CMB Foreground

    CERN Document Server

    Smoot, G F

    1999-01-01

    Synchrotron emission is an important process in Galactic dynamics and a potentially confusing foreground for cosmic microwave background (CMB) radiation observations. Though the mechanism of synchrotron emission is well understood, the details for the Galaxy and many external sources are not well characterized. Quality maps at multiple frequencies are lacking but needed for a full understanding of the Galactic synchrotron emission, including intensity, spectrum, and spectral variation. At high frequencies (> 70 GHz) synchrotron emission is not a severe limitation to precise CMB observations well away from the Galactic plane.

  9. Compact synchrotron radiation source

    International Nuclear Information System (INIS)

    A compact 800 MeV synchrotron radiation source is discussed. The storage ring has a circumference of 30.3 m, two 90 degree and four 45 degree bending magnet sections, two long straight sections and four short straight sections. The radius of the bending magnet is 2.224m. The critical wave length is 24A. The injector is a 15 Mev Microtron Electrons are accelerated from 15 Mev to 800 Mev by ramping the field of the ring. The expected stored current will be around 100 ma

  10. The synchrotron radiation

    International Nuclear Information System (INIS)

    Synchrotron Radiation is a fantastic source of electromagnetic radiation the energy spectrum of which spreads continuously from the far infrared to hard X-rays. For this reason a wide part of the scientific community, fundamentalists as well as industry, is concerned by its use. We shall describe here the main properties of this light source and give two examples of application in the field of characterization of materials: EXAFS (Extended X-Ray Absorption Fine Structure) and X-ray fluorescence. (author). 8 figs., 21 refs

  11. High temperature thermal stability of the HfO2/Ge (100) interface as a function of surface preparation studied by synchrotron radiation core level photoemission

    International Nuclear Information System (INIS)

    High resolution soft x-ray photoemission spectroscopy (SXPS) have been used to study the high temperature thermal stability of ultra-thin atomic layer deposited (ALD) HfO2 layers (∼1 nm) on sulphur passivated and hydrofluoric acid (HF) treated germanium surfaces. The interfacial oxides which are detected for both surface preparations following HfO2 deposition can be effectively removed by annealing upto 700 °C without any evidence of chemical interaction at the HfO2/Ge interface. The estimated valence and conduction band offsets for the HfO2/Ge abrupt interface indicated that effective barriers exist to inhibit carrier injection.

  12. Synchrotron light beam and a synchrotron light experiment facility

    International Nuclear Information System (INIS)

    In the National Laboratory for High Energy Physics, about two years ago, the requirements of synchrotron light beam in respective measuring instruments were discussed. Then, also the arrangement (lattice) of a storage ring, the nature of synchrotron light beam, a synchrotron light experiment facility and the arrangement of the beam lines were studied. During the period of two years since then, due to the changes in the circumstances, the design of the lattice was altered. Accordingly, the arrangement of the beam lines and of measuring instruments were largely changed. At this point, the results of discussions in various meetings are described, though they may still be subject to future changes, with due consideration to beam, environment and beam lines required for the design of the measuring instruments: (1) storage ring and synchrotron light beam, (2) requirements on small beam size and beam stability, (3) a synchrotron light experiment facility. (J.P.N.)

  13. Synchrotron radiation source Indus-1

    International Nuclear Information System (INIS)

    Indus-1 is a 450 MeV electron storage ring for the production of the synchrotron radiation in VUV range with a critical wavelength of 61 A. In this paper we discuss the synchrotron radiation source Indus-1 and report some results of its present performance. Besides, results of beam lifetime studies are also reported. (author)

  14. SAXS experiments using synchrotron sources

    International Nuclear Information System (INIS)

    The main characteristics of SAXS (small angle x-ray scattering) experimental instruments associated with classical and synchrotron sources are outlined. Some examples of applications of synchrotron radiation to SAXS studies of solid state phase separation, molecular aggregation, gel formation, porous materials and sintering processes, are described. An overview of recent instrumental progress and tendencies is presented

  15. Induction synchrotron and its applications

    International Nuclear Information System (INIS)

    An RF synchrotron has been the indispensable device for nuclear physics and high energy physics experiments so far. Instead of this conventional accelerator, an induction synchrotron has been proposed and its demonstration is going to be done in the near future. The induction synchrotron is capable of accelerating a super-bunch of 1 μs long. A new generation of proton driver or hadron collider accommodating super-bunches, which claims to increase their luminosity ten times larger, is under consideration. Key devices to realize the novel induction synchrotron are a pulse modulator and induction accelerating cavity being operated at 1 MHz rep-rate. The concept and characteristics of the induction synchrotron are presented including the outline of R and D works. (author)

  16. Phase contrast portal imaging using synchrotron radiation

    International Nuclear Information System (INIS)

    Microbeam radiation therapy is an experimental form of radiation treatment with great potential to improve the treatment of many types of cancer. We applied a synchrotron radiation phase contrast technique to portal imaging to improve targeting accuracy for microbeam radiation therapy in experiments using small animals. An X-ray imaging detector was installed 6.0 m downstream from an object to produce a high-contrast edge enhancement effect in propagation-based phase contrast imaging. Images of a mouse head sample were obtained using therapeutic white synchrotron radiation with a mean beam energy of 130 keV. Compared to conventional portal images, remarkably clear images of bones surrounding the cerebrum were acquired in an air environment for positioning brain lesions with respect to the skull structure without confusion with overlapping surface structures

  17. Mechanism of degradation of surface hardening at elevated temperature in TiAlV-alloys by in situ synchrotron radiation diffraction

    CERN Document Server

    Berberich, F; Kreissig, U; Schell, N; Mücklich, A

    2003-01-01

    The surface hardness of the technically important alloy Ti-6Al-4V (wt.%) can be improved by nitrogen implantation. The structural mechanisms of hardening and of the stability of the improved hardness at elevated temperatures are studied. Ion implanted (II) and plasma immersion ion implanted (PII) samples were used. The formation of small TiN crystallites was detected in the as-implanted state, but only for the II samples a considerable surface hardness increase (factor 3) is observed. The in situ XRD experiments showed, that the TiN phase is stable up to temperatures of 650 deg. C for both types of implantation. At higher temperature Ti sub 2 N is formed which is stable up to 770 deg. C. ERDA results indicate a diffusion of nitrogen into the bulk material. The redistribution of N is responsible for the hardness changes: a slight decrease for II samples but an improvement by a factor of 2.5 for PII samples. The improvements/degradations of hardness and wear are discussed in correlation with the nitrogen depth ...

  18. Proton synchrotron accelerator theory

    International Nuclear Information System (INIS)

    This is the text of a series of lectures given as part of the CERN Academic Training Programme and primarily intended for young engineers and technicians in preparation for the running-in of the 400 GeV Super Proton Synchrotron (SPS). Following the definition of basic quantities, the problems of betatron motion and the effect of momentum spread and orbital errors on the transverse motion of the beam are reviewed. Consideration is then given to multipole fields, chromaticity and non-linear resonances. After dealing with basic relations governing longitudinal beam dynamics, the space-charge, resistive-wall and other collective effects are treated, with reference to precautions in the SPS to prevent their occurrence. (Auth.)

  19. A six-circle diffractometer system for synchrotron X-ray studies of surfaces and thin film growth by molecular beam epitaxy

    International Nuclear Information System (INIS)

    A new ultrahigh vacuum (UHV) surface diffractometer system equipped with molecular beam epitaxy (MBE) capabilities has been developed. It has a versatile 6-circle configuration for defining the diffraction geometry, and a three-axis translation stage for controlling the sample position. Rugged mechanical components are employed in the design to allow accurate diffraction measurements. Sample cooling is facilitated by passing liquid nitrogen into a reservoir in the base of a sample mount. The sample can be heated to very high temperatures by either direct current heating or electron beam bombardment. During film growth and processing, the sample temperature, monitored by thermocouples, can be continuously and rapidly varied between ∼110 K to above room temperature. A charge coupled device (CCD) camera, attached to the μ circle, allows rapid reciprocal space mapping for real time studies of sample growth and evolution during deposition and annealing. A beam stop and a baffle are implemented to minimize stray scattered radiation

  20. Synchrotron refraction CT and synchrotron bragg magnification CT for NDE

    International Nuclear Information System (INIS)

    X-Ray Refraction Topography techniques are based on Ultra Small Angle Scattering by micro structural elements causing phase related effects like refraction and total reflection at a few minutes of arc as the refractive index of X-rays is nearly unity. The refraction contrast is several times higher than 'true absorption' and results in images of cracks, pores and fibre de-bonding separations below the spatial resolution of the detector. In most cases the investigated inner surface and interface structures correlate to mechanical properties. For the exploration of micro structured materials the refraction technique has been improved by a 3D Synchrotron Refraction Computed Tomography test station. The specimen is placed in an X-ray beam between two single crystals, which suppresses all sample scattering. In addition an asymmetric cut second crystal can magnify the image up to 50 times revealing nano meter resolution. The technique is an alternative to other attempts on raising the spatial resolution of CT machines. (authors)

  1. The European Synchrotron Radiation Facility

    DEFF Research Database (Denmark)

    Buras, B.; Materlik, G.

    In recent years, X-ray synchrotron radiation became a powerful tool for studies of condensed matter, and in view of that a proposal for the construction of a European Synchrotron Radiation Facility (ESRF) was elaborated in some detail by the European Synchrotron Radiation Project. The heart of the...... great flexibility and a small emittance (7×10−9 rad m) leading to a very high brilliance (1019 photons/(s mm2 mrad2) in a relative bandwidth of 0.1% in case of a 1 Å undulator). The overview, as seen from the users point of view, gives a brief account of the storage ring, emitted radiation...

  2. Biomedical applications of synchrotron radiation

    International Nuclear Information System (INIS)

    Synchrotron radiation techniques application in medical diagnostics have been presented especially for: trace element analysis in tissues, elemental mapping, chemical speciation at trace levels, chemical structure determination. Presented techniques are very useful for early cancer discovery

  3. Mossbauer spectroscopy with synchrotron radiation

    International Nuclear Information System (INIS)

    The principles underlying observation of the Mossbauer effect with synchrotron radiation are explained. The current status of the field is reviewed, and prospects for dedicated experimental stations on third generation machines are discussed

  4. Synchrotron scientists unpack their suitcases

    International Nuclear Information System (INIS)

    Australian Synchrotron will enable 3000 Australian scientists to overcome the tyranny of distance and accelerate their research into fields as diverse as drug development, IVF and self-cleaning textiles

  5. Superpower monochromatic coherent synchrotron radiation

    International Nuclear Information System (INIS)

    Here a special case of coherent synchrotron radiation from relativistic electron bunches distributed uniformly on a circular orbit is investigated. The possibility to obtain a monochromatic intense coherent radiation in the long-wavelength region is shown

  6. Nanoscale surface photoreactions

    Science.gov (United States)

    Wadsworth, Garrett Austin

    Subnanometer-scale properties of molecules and materials have become extremely important to the development of nanoscale and molecular electronics devices, including advanced biological and chemical sensors. The energies (i.e., wavelengths) at which the LSPRs of individual nanoparticles are excited varies depending on their size, thickness, and shape, all of which can be controlled synthetically. Photon-coupled scanning tunneling microscopy uses a total internal reflection scheme to couple light into a tunneling junction, generating this specific LSPR in individual Au and Ag nanoprisms. By controlling and coupling this specific excitation to molecular assemblies, the effective photoreactivities and photoconductances of organic molecules can be measured and manipulated. Nanoparticle synthesis methods were developed to produce nanoprisms with appropriate dimensions and homogeneity. Functionalization of the sample surface using alkanedithiols and p-terphenyl-4,4"-dithiol enabled the adsorption dispersion of nanoprisms onto substrates with high density yet minimal stacking. Insertion into self-assembled monolayers was used to arrange single molecules on Au{111} and Ag{111} nanoprisms for selective surface plasmonic enhancement. Scanning tunneling microscopy measurements were collected for molecules adsorbed on the dispersed nanoprisms. Photon STM will be used to monitor the photoactivities of molecules on these substrates, such as photocurrent, photoconductance, and photoreaction.

  7. New developments in the application of synchrotron radiation to material science

    International Nuclear Information System (INIS)

    Recent developments in the application of synchrotrons radiation to materials science are discussed, using techniques which exploit the high brilliance of the newer synchrotrons sources, such as microbeam techniques and correlation spectroscopy. These include studies of environmental systems, residual stress, slow dynamics of condensed matter systems and studies of liquid surfaces and thin magnetic films

  8. Synchrotron Emission on the Largest Scales: Radio Detection of the Cosmic-Web

    Indian Academy of Sciences (India)

    Shea D. Brown

    2011-12-01

    Shocks and turbulence generated during large-scale structure formation are predicted to produce large-scale, low surface-brightness synchrotron emission. On the largest scales, this emission is globally correlated with the thermal baryon distribution, and constitutes the `synchrotron cosmic-web’. I present the observational prospects and challenges for detecting this faint emission with upcoming SKA pathfinders.

  9. Glancing angle synchrotron X-ray diffraction

    International Nuclear Information System (INIS)

    This paper describes in basic detail some of the techniques that can be used to study thin films and surfaces. These are all in the X-ray region and cover reflectivity, diffraction form polycrystalline films, textured films and single crystal films. Other effects such as fluorescence and diffuse scattering are mentioned but not discussed in detail. Two examples of the reflectivity from multilayers and the diffraction from iron oxide films are discussed. The advantages of the synchrotron for these studies is stressed and the experimental geometries that can be employed are described i detail. A brief bibliography is provided at the end to accompany this part of the 1996 Frascati school

  10. Spherical quartz crystals investigated with synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, N. R. [Ecopulse, Inc., 7844 Vervain Ct., Springfield, Virginia 22152 (United States); Macrander, A. T. [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Hill, K. W. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08536 (United States); Baronova, E. O. [Kurchatov Institute, Moscow (Russian Federation); George, K. M.; Kotick, J. [The Ohio State University, Columbus, Ohio 43210 (United States)

    2015-10-15

    The quality of x-ray spectra and images obtained from plasmas with spherically bent crystals depends in part on the crystal’s x-ray diffraction across the entire crystal surface. We employ the energy selectivity and high intensity of synchrotron radiation to examine typical spherical crystals from alpha-quartz for their diffraction quality, in a perpendicular geometry that is particularly convenient to examine sagittal focusing. The crystal’s local diffraction is not ideal: the most noticeable problems come from isolated regions that so far have failed to correlate with visible imperfections. Excluding diffraction from such problem spots has little effect on the focus beyond a decrease in background.

  11. Spherical quartz crystals investigated with synchrotron radiation

    International Nuclear Information System (INIS)

    The quality of x-ray spectra and images obtained from plasmas with spherically bent crystals depends in part on the crystal’s x-ray diffraction across the entire crystal surface. We employ the energy selectivity and high intensity of synchrotron radiation to examine typical spherical crystals from alpha-quartz for their diffraction quality, in a perpendicular geometry that is particularly convenient to examine sagittal focusing. The crystal’s local diffraction is not ideal: the most noticeable problems come from isolated regions that so far have failed to correlate with visible imperfections. Excluding diffraction from such problem spots has little effect on the focus beyond a decrease in background

  12. Spherical quartz crystals investigated with synchrotron radiation

    Science.gov (United States)

    Pereira, N. R.; Macrander, A. T.; Hill, K. W.; Baronova, E. O.; George, K. M.; Kotick, J.

    2015-10-01

    The quality of x-ray spectra and images obtained from plasmas with spherically bent crystals depends in part on the crystal's x-ray diffraction across the entire crystal surface. We employ the energy selectivity and high intensity of synchrotron radiation to examine typical spherical crystals from alpha-quartz for their diffraction quality, in a perpendicular geometry that is particularly convenient to examine sagittal focusing. The crystal's local diffraction is not ideal: the most noticeable problems come from isolated regions that so far have failed to correlate with visible imperfections. Excluding diffraction from such problem spots has little effect on the focus beyond a decrease in background.

  13. Glancing angle synchrotron X-ray diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Cernik, R.J. [Daresbury Lab., Warrington, WA (United States)

    1996-09-01

    This paper describes in basic detail some of the techniques that can be used to study thin films and surfaces. These are all in the X-ray region and cover reflectivity, diffraction form polycrystalline films, textured films and single crystal films. Other effects such as fluorescence and diffuse scattering are mentioned but not discussed in detail. Two examples of the reflectivity from multilayers and the diffraction from iron oxide films are discussed. The advantages of the synchrotron for these studies is stressed and the experimental geometries that can be employed are described i detail. A brief bibliography is provided at the end to accompany this part of the 1996 Frascati school.

  14. Role of functional groups in surface bonding of planar π-conjugated molecules

    Science.gov (United States)

    Bauer, Oliver; Mercurio, Giuseppe; Willenbockel, Martin; Reckien, Werner; Heinrich Schmitz, Christoph; Fiedler, Benjamin; Soubatch, Serguei; Bredow, Thomas; Tautz, Frank Stefan; Sokolowski, Moritz

    2012-12-01

    The trends in the bonding mechanism of 3,4,9,10-perylenetetracarboxylic acid dianhydride (PTCDA) to the Ag(111), Ag(100), and Ag(110) surfaces were analyzed on the basis of data obtained from x-ray standing waves and dispersion-corrected density functional theory. Of importance are the attractive local O-Ag bonds on the anhydride groups. They are the shorter, the more open the surface is, and lead even to partly repulsive interactions between the perylene core and the surface. In parallel, there is an increasing charge donation from the Ag surface into the π system of the PTCDA. This synergism explains the out-of-plane distortion of the adsorbed PTCDA and the surface buckling.

  15. Review Article: Structures of phthalocyanine molecules on surfaces studied by STM

    Directory of Open Access Journals (Sweden)

    Yongfeng Wang

    2012-12-01

    Full Text Available This review mainly focuses on progress recently achieved in the growth of phthalocyanine molecules on single-crystal surfaces of sub-monolayer up to few-monolayer thin films studied by scanning tunneling microscopy in our groups. On metallic surfaces such as Au(111, Ag(111 and Cu(111, molecular superstructures are determined by combining directional intermolecular interactions caused by symmetry reduction, molecule-substrate interactions and indirect long-range interactions due to quantum interference of surface state electrons. On semiconducting TiO2 surface, molecular assembling structures are dictated by the strong molecule-substrate interaction. However, on insulating NaCl film, molecule-molecule interaction dominates over the molecule-NaCl coupling, leading to molecular growth behavior. Knowledge obtained from these studies would help people better understand the physicochemical properties of the phthalocyanine molecules at surfaces so that their new applications could be further explored and uncovered in the future.

  16. Fermi surface mapping and heavy hermion behaviour in ARPES on CePt{sub 5} and CeAg{sub 5} surface alloys

    Energy Technology Data Exchange (ETDEWEB)

    Schwab, Holger; Klein, Markus; Nuber, Andreas; Ziroff, Johannes; Mulazzi, Mattia; Reinert, Friedrich [Universitaet Wuerzburg, Experimentelle Physik VII, Am Hubland, D-97074 Wuerzburg (Germany); Hayashi, H.; Jiang, Jian [Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526 (Japan); Shimada, Kenya [Hiroshima Synchrotron Radiation Center, Hiroshima University, Higashi-Hiroshima 739-0046 (Japan); Assaad, F.F. [Universitaet Wuerzburg, Institut fuer Theoretische Physik und Astrophysik, Am Hubland, D-97074 Wuerzburg (Germany)

    2011-07-01

    Using high-resolution angle-resolved photoemission we studied ordered cerium surface alloys on Pt(111) and Ag(111) surfaces. We present light polarization dependent bandstructure and Fermi surfaces for several photon energies including Ce 4d-4f resonant photoemission. In the CePt{sub 5} surface alloy, we show the temperature dependence of the Cerium 4f electron spectral weight near the Fermi level. There we observed the opening of a hybridisation gap between the flat 4f Cerium band and one strongly dispersing Pt conduction band that has a strong temperature dependence. The comparison to LDA+DMFT calculations based on an NCA solver shows the on-set of the coherent heavy fermion state at low temperature below the Kondo temperature of the material.

  17. Vacuum chambers full of ideas for the Swedish synchrotron

    CERN Multimedia

    Corinne Pralavorio

    2016-01-01

    CERN’s Vacuum, Surfaces and Coatings group has contributed to the development of vacuum chambers for the MAX IV synchrotron, which has just been officially opened in Sweden.   A section of the new 3 GeV MAX IV synchrotron at the time of installation. In the centre of the magnets you can see the vacuum chamber developed in collaboration with CERN. (Photo: Marek Grabski, MAX IV Vacuum group) On 21 June, the King and the Prime Minister of Sweden officially opened MAX IV, a brand-new synchrotron in Lund, Sweden. The summer solstice, the longest day of the year, was deliberately chosen for the ceremony: MAX IV, a cutting-edge synchrotron, will deliver the brightest X-rays ever produced to more than 2000 users. Some 1500 kilometres away, a team at CERN followed the opening ceremony with a touch of pride. The Vacuum, Surfaces and Coatings group in the Technology department (TE-VSC) participated in the construction of this new synchrotron. Its contribution lies at the very hea...

  18. Spin Echo in Synchrotrons

    Energy Technology Data Exchange (ETDEWEB)

    Chao, Alexander W.; /SLAC; Courant, Ernest D.; /Brookhaven

    2006-12-01

    As a polarized beam is accelerated through a depolarization resonance, its polarization is reduced by a well-defined calculable reduction factor. When the beam subsequently crosses a second resonance, the final beam polarization is considered to be reduced by the product of the two reduction factors corresponding to the two crossings, each calculated independently of the other. This is a good approximation when the spread of spin precession frequency {Delta}{nu}{sub spin} of the beam (particularly due to its energy spread) is sufficiently large that the spin precession phases of individual particles smear out completely during the time {tau} between the two crossings. This approximate picture, however, ignores two spin dynamics effects: an interference effect and a spin echo effect. This paper is to address these two effects. The interference effect occurs when {Delta}{nu}{sub spin} is too small, or when {tau} is too short, to complete the smearing process. In this case, the two resonance crossings interfere with each other, and the final polarization exhibits constructive or destructive patterns depending on the exact value of {tau}. Typically, the beam's energy spread is large and this interference effect does not occur. To study this effect, therefore, it is necessary to reduce the beam energy spread and to consider two resonance crossings very close to each other. The other mechanism, also due to the interplay between two resonance crossings, is spin echo. It turns out that even when the precession phases appear to be completely smeared between the two crossings, there will still be a sudden and short-lived echo signal of beam polarization at a time {tau} after the second crossing; the magnitude of which can be as large as 57%. This echo signal exists even when the beam has a sizable energy spread and when {tau} is very large, and could be a sensitive (albeit challenging) way to experimentally test the intricate spin dynamics in a synchrotron. After giving

  19. Vacuum design of advanced and compact synchrotron light sources

    International Nuclear Information System (INIS)

    This book contains papers dealing with the following main topics: Vacuum considerations for synchrotron radiation sources; Machine design; Compact light sources for x-ray lithography; Surface cleaning and conditioning; Ion trapping, gas desorption, lifetime; Wigglers, undulators chamber design; and General conditioning of pumps, machines and gauges

  20. Contact microscopy with synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Panessa-Warren, B.J.

    1985-10-01

    Soft x-ray contact microscopy with synchrotron radiation offers the biologist and especially the microscopist, a way to morphologically study specimens that could not be imaged by conventional TEM, STEM or SEM methods (i.e. hydrated samples, samples easily damaged by an electron beam, electron dense samples, thick specimens, unstained low contrast specimens) at spatial resolutions approaching those of the TEM, with the additional possibility to obtain compositional (elemental) information about the sample as well. Although flash x-ray sources offer faster exposure times, synchrotron radiation provides a highly collimated, intense radiation that can be tuned to select specific discrete ranges of x-ray wavelengths or specific individual wavelengths which optimize imaging or microanalysis of a specific sample. This paper presents an overview of the applications of x-ray contact microscopy to biological research and some current research results using monochromatic synchrotron radiation to image biological samples. 24 refs., 10 figs.

  1. Contact microscopy with synchrotron radiation

    International Nuclear Information System (INIS)

    Soft x-ray contact microscopy with synchrotron radiation offers the biologist and especially the microscopist, a way to morphologically study specimens that could not be imaged by conventional TEM, STEM or SEM methods (i.e. hydrated samples, samples easily damaged by an electron beam, electron dense samples, thick specimens, unstained low contrast specimens) at spatial resolutions approaching those of the TEM, with the additional possibility to obtain compositional (elemental) information about the sample as well. Although flash x-ray sources offer faster exposure times, synchrotron radiation provides a highly collimated, intense radiation that can be tuned to select specific discrete ranges of x-ray wavelengths or specific individual wavelengths which optimize imaging or microanalysis of a specific sample. This paper presents an overview of the applications of x-ray contact microscopy to biological research and some current research results using monochromatic synchrotron radiation to image biological samples. 24 refs., 10 figs

  2. Thermal loading considerations for synchrotron radiation mirrors

    International Nuclear Information System (INIS)

    Grazing incidence mirrors used to focus synchrotron radiation beams through small distant apertures have severe optical requirements. The surface distortion due to heat loading of the first mirror in a bending magnet beam line is of particular concern when a large fraction of the incident beam is absorbed. In this paper we discuss mirror design considerations involved in minimizing the thermal/mechanical loading on vertically deflecting first surface mirrors required for SPEAR synchrotron radiation beam lines. Topics include selection of mirror material and cooling method, the choice of SiC for the substrate, optimization of the thickness, and the design of the mirror holder and cooling mechanism. Results obtained using two-dimensional, finite-element thermal/mechanical distortion analysis are presented for the case of a 60 grazing incidence SiC mirror absorbing up to 260 W at Beam Line VIII on the SPEAR ring. Test descriptions and results are given for the material used to thermally couple this SiC mirror to a water-cooled block. The interface material is limited to applications for which the equivalent normal heat load is less than 20 W/cm2

  3. Off-lattice self-learning kinetic Monte Carlo: application to 2D cluster diffusion on the fcc(111) surface

    International Nuclear Information System (INIS)

    We report developments of the kinetic Monte Carlo (KMC) method with improved accuracy and increased versatility for the description of atomic diffusivity on metal surfaces. The on-lattice constraint built into our recently proposed self-learning KMC (SLKMC) (Trushin et al 2005 Phys. Rev. B 72 115401) is released, leaving atoms free to occupy 'off-lattice' positions to accommodate several processes responsible for small-cluster diffusion, periphery atom motion and heteroepitaxial growth. This technique combines the ideas embedded in the SLKMC method with a new pattern-recognition scheme fitted to an off-lattice model in which relative atomic positions are used to characterize and store configurations. Application of a combination of the 'drag' and the repulsive bias potential (RBP) methods for saddle point searches allows the treatment of concerted cluster, and multiple- and single-atom, motions on an equal footing. This tandem approach has helped reveal several new atomic mechanisms which contribute to cluster migration. We present applications of this off-lattice SLKMC to the diffusion of 2D islands of Cu (containing 2-30 atoms) on Cu and Ag(111), using the interatomic potential from the embedded-atom method. For the hetero-system Cu/Ag(111), this technique has uncovered mechanisms involving concerted motions such as shear, breathing and commensurate-incommensurate occupancies. Although the technique introduces complexities in storage and retrieval, it does not introduce noticeable extra computational cost.

  4. The Australian Synchrotron Project - Update

    CERN Document Server

    Jackson, Alan

    2004-01-01

    The Australian Synchrotron - a synchrotron light facility based on a 3-GeV electron storage ring is under construction at a site in the Metropolitan District of Melbourne. Building preparation started on a "green-field" site in September 2003 and staff moved in to their new offices in February 2005. Installation of the technical equipment started in April 2005 with all accelerator contracts expected to be completed before April 2006. Storage Ring commissioning with beam will start in June 2006, and project completion is scheduled for March 2007. In this paper we present an overview of the facility and discuss progress to date in meeting this very aggressive schedule.

  5. Synchrotron radiation and structural proteomics

    CERN Document Server

    Pechkova, Eugenia

    2011-01-01

    This book presents an overview of the current state of research in both synchrotron radiation and structural proteomics from different laboratories worldwide. The book presents recent research results in the most advanced methods of synchrotron radiation analysis, protein micro- and nano crystallography, X-ray scattering and X-ray optics, coherent X-Ray diffraction, and laser cutting and contactless sample manipulation are described in details. The book focuses on biological applications and highlights important aspects such as radiation damage and molecular modeling.

  6. DESY: Synchrotron and storage rings

    CERN Multimedia

    1972-01-01

    An improvement programme has been under way for several years at the 7.5 GeV électron synchrotron at DESY. In particular it has been designed to increase the accelerated beam intensity, to achieve better quality of the ejected électron beams and photon beams and to improve machine reliability.

  7. Biological physics and synchrotron radiation

    International Nuclear Information System (INIS)

    This conference deals with the applications of synchrotron radiation to current problems in biology and medicine. Seven sessions take stock on the subject: sources and detectors; inelastic scattering and dynamics; muscle diffraction; reaction mechanisms; macromolecular assemblies; medical applications; imaging and spectroscopy. The document presents the papers abstracts. (A.L.B.)

  8. Biological physics and synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Filhol, J.M.; Chavanne, J. [European Synchrotron Radiation Facility, 38 - Grenoble (France); Weckert, E. [Hasylab at Desy, Hamburg (Germany)] [and others

    2001-07-01

    This conference deals with the applications of synchrotron radiation to current problems in biology and medicine. Seven sessions take stock on the subject: sources and detectors; inelastic scattering and dynamics; muscle diffraction; reaction mechanisms; macromolecular assemblies; medical applications; imaging and spectroscopy. The document presents the papers abstracts. (A.L.B.)

  9. Synchrotron radiation in material science

    International Nuclear Information System (INIS)

    A brief review on the several experimental techniques (XRD, SAXS, EXAFS, IRRS, etc...) which, utilizing of synchrotron radiation can be applied in glass structural studies, is presented. The major part of these techniques can be also used for studies of other materials such as polymers, metals, etc... (L.C.)

  10. Synchrotron radiation and biomedical imaging

    International Nuclear Information System (INIS)

    In this lecture we describe the characteristics of Synchrotron radiation as a source of X rays. We discuss the properties of SR arc sources, wigglers, undulators and the use of backscattering of laser light. Applications to angiography, X ray microscopy and tomography are reviewed. 16 refs., 23 figs

  11. Monte Carlo Simulations of the Adsorption of Anisotropic Noninteracting Molecules on the (111) Surface of a FCC Crystal

    Science.gov (United States)

    Filimonov, S. N.; Hervieu, Yu. Yu.

    2016-04-01

    We present results of computer Monte Carlo simulations of the formation of adsorption layers composed of noninteracting molecules of benzene, anthracene, and pentacene on the Ag(111) surface. The dependences of the chemical potential of the molecules on the density of the molecular layer (surface coverage) are obtained. By means of the thermodynamic integration method the configurational entropy of the molecular layer is evaluated as a function of surface coverage. It is shown that the substitution of benzene by pentacene results in a more than twofold decrease of the maximum entropy of the molecular layer. The presence of steps on the substrate surface also leads to a decrease of the molecular layer entropy. If the distance between the steps is comparable to the linear size of the molecule, the molecules in dense adsorption layers orient preferentially parallel to the step edges.

  12. Understanding the Adsorption of CuPc and ZnPc on Noble Metal Surfaces by Combining Quantum-Mechanical Modelling and Photoelectron Spectroscopy

    Directory of Open Access Journals (Sweden)

    Yu Li Huang

    2014-03-01

    Full Text Available Phthalocyanines are an important class of organic semiconductors and, thus, their interfaces with metals are both of fundamental and practical relevance. In the present contribution we provide a combined theoretical and experimental study, in which we show that state-of-the-art quantum-mechanical simulations are nowadays capable of treating most properties of such interfaces in a quantitatively reliable manner. This is shown for Cu-phthalocyanine (CuPc and Zn-phthalocyanine (ZnPc on Au(111 and Ag(111 surfaces. Using a recently developed approach for efficiently treating van der Waals (vdW interactions at metal/organic interfaces, we calculate adsorption geometries in excellent agreement with experiments. With these geometries available, we are then able to accurately describe the interfacial electronic structure arising from molecular adsorption. We find that bonding is dominated by vdW forces for all studied interfaces. Concomitantly, charge rearrangements on Au(111 are exclusively due to Pauli pushback. On Ag(111, we additionally observe charge transfer from the metal to one of the spin-channels associated with the lowest unoccupied π-states of the molecules. Comparing the interfacial density of states with our ultraviolet photoelectron spectroscopy (UPS experiments, we find that the use of a hybrid functionals is necessary to obtain the correct order of the electronic states.

  13. Estimation of presampling modulation transfer function in synchrotron radiation microtomography

    CERN Document Server

    Mizutani, Ryuta; Takeuchi, Akihisa; Uesugi, Kentaro; Suzuki, Yoshio

    2016-01-01

    The spatial resolution achieved by recent synchrotron radiation microtomographs should be estimated from the modulation transfer function (MTF) on the micrometer scale. Step response functions of a synchrotron radiation microtomograph were determined by the slanted edge method by using high-precision surfaces of diamond crystal and ion-milled aluminum wire. Tilted reconstruction was introduced to enable any edge to be used as the slanted edge by defining the reconstruction pixel matrix in an arbitrary orientation. MTFs were estimated from the step response functions of the slanted edges. The obtained MTFs coincided with MTF values estimated from square-wave patterns milled on the aluminum surface. Although x-ray refraction influences should be taken into account to evaluate MTFs, any flat surfaces with nanometer roughness can be used to determine the spatial resolutions of microtomographs.

  14. Systematic studies of bonding distances of diindenoperylene on noble metal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Buerker, Christoph; Gerlach, Alexander; Hosokai, Takuya; Schreiber, Frank [Institut fuer Angewandte Physik, Universitaet Tuebingen, 72076 Tuebingen (Germany); Niederhausen, Jens; Koch, Norbert [Institut fuer Physik, Humboldt-Universitaet zu Berlin, 12489 Berlin (Germany); Detlefs, Blanka [ESRF, 38043 Grenoble Cedex (France)

    2011-07-01

    The interaction of organic semiconducting molecules with different substrates is essential for the understanding of these systems and for possible applications in organic electronic devices. Diindenoperylene (DIP) is one promising semiconductor and has been studied widely in the recent years concerning its growth and ordering behavior on different substrates as well as electronic properties. Despite these efforts the bonding distance d{sub 0} and thus the coupling to the substrate is still an unknown key parameter of DIP adsorption. Here we present a systematic study of d{sub 0} of DIP on Cu(111), Ag(111) and Au(111) surfaces, determined by the X-ray standing wave (XSW) technique. Different bonding distances for different substrates indicate a substrate dependent interaction strength. Our results are compared with the well-established bonding distances and interaction strength of PTCDA on the same noble metal surfaces. Interesting similarities as well as differences between the two molecules are discussed.

  15. Sub-monolayer film growth of a volatile lanthanide complex on metallic surfaces

    Directory of Open Access Journals (Sweden)

    Hironari Isshiki

    2015-12-01

    Full Text Available We deposited a volatile lanthanide complex, tris(2,2,6,6-tetramethyl-3,5-heptanedionatoterbium(III, onto metal surfaces of Cu(111, Ag(111 and Au(111 in vacuum and observed well-ordered sub-monolayer films with low temperature (5 K scanning tunneling microscopy. The films show a distorted three-fold symmetry with a commensurate structure. Scanning tunneling spectroscopy reveals molecular orbitals delocalized on the ligands of the molecule. Our results imply that this complex can be transferred onto the metal substrates without molecular decomposition or contamination of the surface. This new rare-earth-based class of molecules broadens the choice of molecular magnets to study with scanning tunneling microscopy.

  16. Medical applications of synchrotron radiation

    International Nuclear Information System (INIS)

    Ever since the first diagnostic x-ray was done in the United States on February 3, 1896, the application of ionizing radiation to the field of medicine has become increasingly important. Both in clinical medicine and basic research the use of x-rays for diagnostic imaging and radiotherapy is now widespread. Radiography, angiography, CAT and PETT scanning, mammography, and nuclear medicine are all examples of technologies developed to image the human anatomy. In therapeutic applications, both external and internal sources of radiation are applied to the battle against cancer. The development of dedicated synchrotron radiation sources has allowed exciting advances to take place in many of these applications. The new sources provide tunable, high-intensity monochromatic beams over a wide range of energies which can be tailored to specific programmatic needs. This paper surveys those areas of medical research in which synchrotron radiation facilities are actively involved

  17. Multipole correction in large synchrotrons

    International Nuclear Information System (INIS)

    A new method of correcting dynamic nonlinearities due to the multipole content of a synchrotron such as the Superconducting Super Collider is discussed. The method uses lumped multipole elements placed at the center (C) of the accelerator half-cells as well as elements near the focusing (F) and defocusing (D) quads. In a first approximation, the corrector strengths follow Simpson's Rule. Correction of second-order sextupole nonlinearities may also be obtained with the F, C, and D octupoles. Correction of nonlinearities by about three orders of magnitude are obtained, and simple solutions to a fundamental problem in synchrotrons are demonstrated. Applications to the CERN Large Hadron Collider and lower energy machines, as well as extensions for quadrupole correction, are also discussed

  18. Medical Applications of Synchrotron Radiation

    Science.gov (United States)

    Thomlinson, W.

    1991-10-01

    Ever since the first diagnostic x-ray was done in the United States on February 3, 1896, the application of ionizing radiation to the field of medicine has become increasingly important. Both in clinical medicine and basic research the use of x-rays for diagnostic imaging and radiotherapy is now widespread. Radiography, angiography, CAT and PETT scanning, mammography, and nuclear medicine are all examples of technologies developed to image the human anatomy. In therapeutic applications, both external and internal sources of radiation are applied to the battle against cancer. The development of dedicated synchrotron radiation sources has allowed exciting advances to take place in many of these applications. The new sources provide tunable, high-intensity monochromatic beams over a wide range of energies which can be tailored to specific programmatic needs. This paper surveys those areas of medical research in which synchrotron radiation facilities are actively involved.

  19. Threedimensional microfabrication using synchrotron radiation

    International Nuclear Information System (INIS)

    For fabricating microstructures with extreme structural heights a technology has been developed which is based on deep-etch lithography and subsequent replication processes. A particularly high precision is achieved if the lithographic process is carried out by means of synchrotron radiation. Electroforming and molding processes are used for the replication of microstructures from a large variety of materials. The field of application comprises sensors, electrical and optical microconnectors, components for fluid technology, microfiltration systems and novel composite materials. (author)

  20. Optical substrate materials for synchrotron radiation beamlines

    Energy Technology Data Exchange (ETDEWEB)

    Howells, M.R. [Lawrence Berkeley National Lab., CA (United States). Advanced Light Source; Paquin, R.A. [Univ. of Arizona, Tucson, AZ (United States). Optical Sciences Center

    1997-06-01

    The authors consider the materials choices available for making optical substrates for synchrotron radiation beam lines. They find that currently the optical surfaces can only be polished to the required finish in fused silica and other glasses, silicon, CVD silicon carbide, electroless nickel and 17-4 PH stainless steel. Substrates must therefore be made of one of these materials or of a metal that can be coated with electroless nickel. In the context of material choices for mirrors they explore the issues of dimensional stability, polishing, bending, cooling, and manufacturing strategy. They conclude that metals are best from an engineering and cost standpoint while the ceramics are best from a polishing standpoint. They then give discussions of specific materials as follows: silicon carbide, silicon, electroless nickel, Glidcop{trademark}, aluminum, precipitation-hardening stainless steel, mild steel, invar and superinvar. Finally they summarize conclusions and propose ideas for further research.

  1. Optical substrate materials for synchrotron radiation beamlines

    International Nuclear Information System (INIS)

    The authors consider the materials choices available for making optical substrates for synchrotron radiation beam lines. They find that currently the optical surfaces can only be polished to the required finish in fused silica and other glasses, silicon, CVD silicon carbide, electroless nickel and 17-4 PH stainless steel. Substrates must therefore be made of one of these materials or of a metal that can be coated with electroless nickel. In the context of material choices for mirrors they explore the issues of dimensional stability, polishing, bending, cooling, and manufacturing strategy. They conclude that metals are best from an engineering and cost standpoint while the ceramics are best from a polishing standpoint. They then give discussions of specific materials as follows: silicon carbide, silicon, electroless nickel, Glidcop trademark, aluminum, precipitation-hardening stainless steel, mild steel, invar and superinvar. Finally they summarize conclusions and propose ideas for further research

  2. A guide to synchrotron radiation science

    CERN Document Server

    Sato, Shigeru; Munro, Ian; Lodha, G S

    2015-01-01

    Synchrotron Radiation (SR), as a light source is now in use around the world to provide brilliant radiation from the infrared into the soft and hard X-ray regions. It is an indispensible and essential tool to establish the physic-chemical characteristics of materials and surfaces from an atomic and molecular view point. It is being applied to topics which range from mineralogy to protein crystallography, embracing research in areas from the physical to the life sciences. This new guide is a concise yet comprehensive and easily readable introduction to an expanding area of science. It presents in a readily assimilable form the basic concepts of SR science from its generation principles, through source design and operation to the principles of instruments for SR exploitation followed by a survey of its actual applications in selected research fields, including spectroscopy, diffractometry, microanalysis and chemical processing.

  3. 3D Detectors for Synchrotron Applications

    CERN Document Server

    Pennicard, D

    2009-01-01

    3D detectors are a novel variety of photodiode radiation detector, invented by Parker, Kenney and Segal (1997). Instead of having n- and p-type contacts on the front and back surfaces of a silicon substrate, like a standard photodiode, they have columns of doped material passing through the thickness of the silicon. This structure means that the detector can combine a reasonable substrate thickness with a very small electrode spacing, resulting in a low depletion voltage, fast charge collection and low charge sharing. These detectors have a couple of promising applications. Their fast charge collection and low depletion voltage should make them very radiation-tolerant. So, they could be used for future particle physics experiments at the Super Large Hadron Collider (SLHC), where high levels of radiation damage are expected. Also, their low charge sharing means they could potentially improve X-ray diffraction measurements at synchrotrons such as Diamond Light Source. This would allow these experiments, for exa...

  4. Silicon Pixel Detectors for Synchrotron Applications

    CERN Document Server

    Stewart, Graeme Douglas

    Recent advances in particle accelerators have increased the demands being placed on detectors. Novel detector designs are being implemented in many different areas including, for example, high luminosity experiments at the LHC or at next generation synchrotrons. The purpose of this thesis was to characterise some of these novel detectors. The first of the new detector types is called a 3D detector. This design was first proposed by Parker, Kenney and Segal (1997). In this design, doped electrodes are created that extend through the silicon substrate. When compared to a traditional photodiode with electrodes on the opposing surfaces, the 3D design can combine a reasonable detector thickness with a small electrode spacing resulting in fast charge collection and limited charge sharing. The small electrode spacing leads to the detectors having lower depletion voltages. This, combined with the fast collection time, makes 3D detectors a candidate for radiation hard applications. These applications include the upgra...

  5. Proposals for synchrotron light sources

    International Nuclear Information System (INIS)

    Ever since it was first applied in the 1960's synchrotron radiation from an accelerating electron beam has been gaining popularity as a powerful tool for research and development in a wide variety of fields of science and technology. By now there are some 20 facilities operating either parasitically or dedicatedly for synchrotron radiation research in different parts of the world. In addition there are another 20 facilities either in construction or in various stages of proposal and design. The experiences gained from the operating facilities and the recent development of insertion devices such as wigglers and undulators as radiation sources led to a new set of requirements on the design of synchrotron radiation storage rings for optimum utility. The surprisingly uniform applicability and unanimous acceptance of these criteria give assurance that they are indeed valid criteria derived form mature considerations and experiences. Instead of describing the design of each of these new facilities it is, thus, more effective to discuss these desirable design features and indicate how they are incorporated in the design using machines listed as examples. 9 refs., 7 figs., 2 tabs

  6. Beam diagnostics with synchrotron radiation

    International Nuclear Information System (INIS)

    Synchrotron radiation is often used to measure the dimensions of an electron beam. The transverse size is obtained from an image of the beam cross section formed by means of the emitted synchrotron radiation. Because of the small natural opening angle the resolution is limited by diffraction. The angular spread of the particles in the beam can be measured by observing the radiation directly. Here, the resolution is limited by the natural opening angle of the emitted light. Measuring both beam cross section and angular spread gives the emittance of the beam. However, in most cases only one of these two parameters is observed and the other deduced from the known particle beam optics at the source of the radiation. Usually one observes radiation emitted in long bending magnets. However, short magnets and undulators are also useful sources for these measurements. For practical reasons the beam diagnostics is carried out using visible or ultraviolet light. This part of the spectrum is usually far below the critical frequency, and corresponding approximations can be applied. Synchrotron radiation is an extremely useful tool for diagnostics in electron (or positron) rings. In some cases it has also served in proton rings using special magnets. (author)

  7. Quantification estimate methods for synchrotron radiation X-ray fluorescence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Bewer, Brian, E-mail: brian.bewer@lightsource.ca

    2015-03-15

    Synchrotron radiation X-ray fluorescence spectroscopy is a method which allows low elemental concentrations to be measured within a sample. To maintain biological or medical relevance increased importance is being placed on quantifying these in situ localized elemental concentrations. For third generation synchrotron light sources, which have the potential for high sample throughput, a rapid method of obtaining a quantification estimate is needed. Non-destructive transmission and surface analysis techniques for first transition metals, or elements of higher atomic number, using reference standards are examined for different sample property regimes to elucidate methods of quantitative synchrotron radiation X-ray fluorescence spectroscopy.

  8. Synchrotron radiation in transactinium research report of the workshop

    International Nuclear Information System (INIS)

    This report contains viewgraphs on the following topics. The advanced light source U8 undulator beamline, 20--300 eV; gas-phase actinide studies with synchrotron radiation; atomic structure calculations for heavy atoms; flux growth of single crystal uranium intermetallics: Extension to transuranics; x-ray absorption near-edge structure studies of actinide compounds; surface as a new stage for studying actinides: Theoretical study of the surface electronic structure of uranium; magnetic x-ray scattering experiments at resonant energies; beamline instruments for radioactive materials; the search for x-ray absorption magnetic circular dichroism in actinide materials: preliminary experiments using UFe2 and U-S; the laser plasma laboratory light source: a source of preliminary transuranic data; electron spectroscopy of heavy fermion actinide materials; study of thin layers of actinides. Present status and future use of synchrotron radiation; electronic structure and correlated-electron theory for actinide materials; and heavy fermion and kondo phenomena in actinide materials

  9. Synchrotron Environmental Science-I Workshop Report

    International Nuclear Information System (INIS)

    Attendees of the Synchrotrons Environmental Science 1 (SES-1) workshop represented a broad spectrum of environmental science research areas and expertise in all of the current synchrotrons techniques (X-ray scattering and diffraction, X-ray absorption spectroscopy, and two- and three-dimensional X-ray imaging). These individuals came together to discuss current measurement obstacles in environmental research and, more specifically, ways to overcome such obstacles by applying synchrotrons radiation techniques. Significant obstacles in measurement affect virtually all of the research issues described. Attendees identified synchrotrons approaches of potential value in their research. A number of the environmental research studies discussed are currently being addressed with some success by synchrotron-based approaches. Nevertheless, improvements in low-Z measurement capabilities are needed to facilitate the use of synchrotrons radiation methodologies in environmental research

  10. Linac for the National Synchrotron Light Source

    International Nuclear Information System (INIS)

    The nominally 100 MeV electron linear accelerator to be used as an injector for the booster synchrotron of the National Synchrotron Light Source is described. The machine utilizes a combination of Varian and SLAC accelerating guides and is interfaced by means of a microprocessor-based Intel Multibus system, to the Data General central control computer. Provision for emittance and momentum measurement is provided in the transport line between the linac and the booster synchrotron

  11. Activity report of Synchrotron Radiation Laboratory 2000

    International Nuclear Information System (INIS)

    In the spring of 2000, the Synchrotron Radiation Laboratory (SRL) moved from Tanashi to Kashiwa Campus. Now, most important for SRL is to promote the future project of High-brilliance Light Source, Super SOR project, in cooperation with the nationwide user group as well as with the users of the University of Tokyo. The Super SOR will be one of the most brilliant light sources in vacuum ultraviolet and soft x-ray regimes. In order to continue extensive efforts on research and developments (R and D) of the light source and beamlines, the SRL Experimental Building has been built at Kashiwa Campus, which acts as the Super SOR Project Office of the University of Tokyo. On the other hand, the SRL has a branch laboratory in the High Energy Accelerator Research Organization (KEK) at Tsukuba. The branch laboratory maintains an undulator called Revolver, two beamlines and three experimental stations (BL-18A, 19A and 19B); they are installed in the Photon Factory (PF) and fully opened to outside users. The in-house staffs not only serve the outside users with technical support and advices, but also carry out their own research works on advanced solid state spectroscopy as well as instrumentation. In the fiscal year of 2000, the operation time of the beamlines wag more than 5000 hours and the number of the users was more than 200. The main scientific interests and activities in the SRL at KEK-PF are directed to the electronic structures of new materials with new transport and optical properties. The electronic structures of solid surfaces and interfaces are also intensively studied. The study of the behavior of electrons in a synchrotron radiation source is indispensable as a part of accelerator physics for developing electron accelerators. The SRL is carrying out research works of the accelerator physics and developing the accelerator-related technology, many parts of which will be directly applied to the Super SOR light source. This report contains the activities of the SRL

  12. Research on feedback system of synchrotron accelerator

    International Nuclear Information System (INIS)

    It is a very complex problem to use feedback control system in synchrotron accelerator. Some scientists design feedback control system to make high energy beam stable in synchrotron accelerator, but it is very rare to see theoretically analysis feedback system in synchrotron accelerator by using new concept of control model. One new feedback control model is a fresh idea to discuss the feedback system more deeply. A topic about feedback control system discussed here will be useful for synchrotron accelerator design and operation. It is an good idea for some scientists and technician to continue study. (authors)

  13. METROLOGICAL CHALLENGES OF SYNCHROTRON RADIATION OPTICS

    International Nuclear Information System (INIS)

    Modern third generation storage rings, require state-of-the-art grazing incidence x-ray optics, in order to monochromate the Synchrotrons Radiation (SR) source photons, and focus them into the experimental stations. Slope error tolerances in the order of 0.5 microRad RMS, and surface roughness well below 5 angstrom RMS, are frequently specified for mirrors and gratings exceeding 300 mm in length. Non-contact scanning instruments were developed, in order to characterize SR optical surfaces, of spherical and aspherical shape. Among these, the Long Trace Profiler (LTP), a double pencil slope measuring interferometer, has proved to be particularly reliable, and was adopted by several SR optics metrology laboratories. The ELETTRA soft x-rays and optics metrology laboratory, has operated an LTP since 1992. We review the basic operating principles of this instrument, and some major instrumental and environmental improvements, that were developed in order to detect slope errors lower than 1 microRad RMS on optical surfaces up to one metre in length. A comparison among measurements made on the same reference flat, by different interferometers (most of them were LTPs) can give some helpful indications in order to optimize the quality of measurement

  14. METROLOGICAL CHALLENGES OF SYNCHROTRON RADIATION OPTICS.

    Energy Technology Data Exchange (ETDEWEB)

    SOSTERO,G.

    1999-05-25

    Modern third generation storage rings, require state-of-the-art grazing incidence x-ray optics, in order to monochromate the Synchrotrons Radiation (SR) source photons, and focus them into the experimental stations. Slope error tolerances in the order of 0.5 {micro}Rad RMS, and surface roughness well below 5 {angstrom} RMS, are frequently specified for mirrors and gratings exceeding 300 mm in length. Non-contact scanning instruments were developed, in order to characterize SR optical surfaces, of spherical and aspherical shape. Among these, the Long Trace Profiler (LTP), a double pencil slope measuring interferometer, has proved to be particularly reliable, and was adopted by several SR optics metrology laboratories. The ELETTRA soft x-rays and optics metrology laboratory, has operated an LTP since 1992. We review the basic operating principles of this instrument, and some major instrumental and environmental improvements, that were developed in order to detect slope errors lower than 1 {micro}Rad RMS on optical surfaces up to one metre in length. A comparison among measurements made on the same reference flat, by different interferometers (most of them were LTPs) can give some helpful indications in order to optimize the quality of measurement.

  15. Time-resolved spectroscopy using synchrotron radiation

    International Nuclear Information System (INIS)

    Work performed at the Stanford Synchrotron Radiation Laboratory (SSRL) is reported. The timing characteristics of the SPEAR beam (pulse width less than or equal to 0.4 nsec, pulse repetition period = 780 nsec) were exploited to determine dynamic behavior of atomic, molecular, excimeric, and photodissociative gas-phase species excited by vacuum-ultraviolet (VUV) radiation. Fast fluorescence timing measurements were done to determine excited-state lifetimes of Kr and Xe. Pressure-dependent timing studies on Xe gas at higher concentrations demonstrated some of the problems associated with previous kinetic modeling of the Xe2 system. It was found that even qualitative agreement of observed Xe2 lifetimes as a function of pressure required the assumption that the radiative lifetime was a strong function of internuclear separation. The radiative decays of chemically unstable fragments, CN* (B2Σ+) and XeF* (B2Σ+ and C2 Pi/sub 3/2//), were studied by pulsed photodissociation of stable parent compounds, ICN and XeF2. When the polarization of the CN* (B2Σ+) fragment fluorescence was measured, it was found to be non-zero and strongly dependent on excitation wavelength. This polarization is related to the symmetry of the photodissociative surface via a classical model, and the variations in the polarization with wavelength is attributed to symmetry and lifetime effects of a predissociating parent molecule. Despite the drawbacks of limited availability and low radiation flux, synchrotron radiation is definitely a useful spectroscopic tool for VUV studies of gas-phase systems

  16. In situ synchrotron X-ray diffraction study of surface scale formation during CO{sub 2} corrosion of carbon steel at temperatures up to 90 {sup o}C

    Energy Technology Data Exchange (ETDEWEB)

    Ingham, B., E-mail: b.ingham@irl.cri.n [Industrial Research Limited, PO Box 31-310, Lower Hutt 5045 (New Zealand); Ko, M. [Quest Integrity Group, PO Box 38-096, Lower Hutt 5045 (New Zealand); Kear, G. [Electrochemical Engineering Laboratory, Energy Technology Research Group, University of Southampton, Southampton SO17 1B (United Kingdom); Kappen, P. [Centre for Materials and Surface Science, Department of Physics, La Trobe University, Bundoora, VIC 3086 (Australia); Laycock, N. [Quest Integrity Group, PO Box 38-096, Lower Hutt 5045 (New Zealand); Kimpton, J.A. [Australian Synchrotron, 800 Blackburn Road, Clayton, VIC 3168 (Australia); Williams, D.E. [MacDiarmid Institute for Advanced Materials and Nanotechnology, Department of Chemistry, University of Auckland, Private Bag 92019, Auckland, 1022 (New Zealand)

    2010-09-15

    In situ synchrotron X-ray diffraction was used to follow the formation of corrosion product scales on carbon steel in CO{sub 2} saturated brine at temperatures from 40 to 90 {sup o}C. The corrosion process was accelerated by applying a small anodic current, and in selected tests a scale inhibitor, amino trimethylene phosphonic acid (ATMPA), was added. Siderite was identified as the major phase in the scale formed in all conditions. With increasing temperature, the scale formation rate increased, while the scale thickness and crystallite size decreased. Above 60 {sup o}C, the scale became increasingly protective. The scale thickness and crystallite size decreased with increasing ATMPA concentration.

  17. Computed tomography using synchrotron radiation

    International Nuclear Information System (INIS)

    X-ray computed tomography (CT) is a widely used method of obtaining cross-sectional views of objects. The high intensity, natural collimation, monochromaticity and energy tunability of synchrotron x-ray sources could potentially be used to provide CT images of improved quality. The advantages of these systems would be that images could be produced more rapidly with better spatial resolution and reduced beam artifacts. In addition, images, in some cases, could be acquired with elemental sensitivity. As a demonstration of the capability of such a system, CT images were obtained of four slices of an excised pig heart in which the arteries and the cardiac chambers were filled with an iodinated medium. Images were taken with incident x-rays tuned successively to energies just above and below the iodine K edge. Iodine specific images were obtained by logarithmically subtracting the low energy image data from the high energy data and then reconstructing the image. CT imaging using synchrotron radiation may become a convenient and non-destructive method of imaging samples difficult to study by other methods

  18. He atom-surface scattering: Surface dynamics of insulators, overlayers and crystal growth

    International Nuclear Information System (INIS)

    This progress report describes work carried out in the study of surface structure and dynamics of ionic insulators, the microscopic interactions controlling epitaxial growth and the formation of overlayers, and energy exchange in multiphonon surface scattering. The approach used is to employ high resolution helium atom scattering to study the geometry and structural features of the surfaces. Experiments have been carried out on the surface dynamics of RbCl and preliminary studies done on CoO and NiO. Epitaxial growth and overlayer dynamics experiments on the systems NaCl/NaCl(001), KBr/NaCl(001), NaCl/KBr(001) and KBr/RbCl(001) have been performed. They have collaborated with two theoretical groups to explore models of overlayer dynamics with which to compare and to interpret their experimental results. They have carried out extensive experiments on the multiphonon scattering of helium atoms from NaCl and, particularly, LiF. Work has begun on self-assembling organic films on gold and silver surfaces (alkyl thiols/Au(111) and Ag(111))

  19. High pressure and synchrotron radiation satellite workshop

    Energy Technology Data Exchange (ETDEWEB)

    Bass, J.; Guignot, N.; Morard, G.; Mezouar, M.; Andrault, D.; Bolfan-Casanova, N.; Sturhahn, W.; Daniel, I.; Reynard, B.; Simionovici, A.; Sanchez Valle, C.; Martinez, I.; Kantor, I.; Dubrovinsky, I.; Mccammon, C.; Dubrovinskaia, N.; Kurnosiv, A.; Kuznetsov, A.; Goncharenko, I.; Loubeyre, P.; Desgreniers, S.; Weck, G.; Yoo, C.S.; Iota, V.; Park, J.; Cynn, H.; Gorelli, F.; Toulemonde, P.; Machon, D.; Merlen, A.; San Miguel, A.; Amboage, M.; Aquilanti, G.; Mathon, O.; Pascarelli, S.; Itie, J.P.; Mcmillan, P.F.; Trapananti, A.; Di Cicco, A.; Panfilis, S. de; Filipponi, A.; Kreisel, J.; Bouvier, P.; Dkhil, B.; Chaabane, B.; Rosner, H.; Koudela, D.; Schwarz, U.; Handestein, A.; Hanfland, M.; Opahle, I.; Koepernik, K.; Kuzmin, M.; Mueller, K.H.; Mydosh, J.; Richter, M.; Hejny, C.; Falconi, S.; Lundegaard, L.F.; Mcmahon, M.I; Loa, I.; Syassen, K.; Wang, X.; Roth, H.; Lorenz, T.; Farber Daniel, I.; Antonangeli Daniele, I.; Krisch, M.; Badro, J.; Fiquet, G.; Occelli, F.; Mao, W.L.; Mao, H.K.; Eng, P.; Kao, C.C.; Shu, J.F.; Hemley, R.J.; Tse, J.S.; Yao, Y.; Deen, P.P.; Paolasini, I.; Braithwaite, D.; Kernavanois, N.; Lapertot, G.; Rupprecht, K.; Leupold, O.; Ponkratz, U.; Wortmann, G.; Beraud, A.; Krisch, M.; Farber, D.; Antonangeli, D.; Aracne, C.; Zarestky, J.L.; Mcqueeney, R.; Mathon, O.; Baudelet, F.; Decremps, F.; Itie, J.P.; Nataf, I.; Pascarelli, S.; Polian, A

    2006-07-01

    The workshop is dedicated to recent advances on science at high pressure at third generation synchrotron sources. A variety of experiments using synchrotron radiation techniques including X-ray diffraction, EXAFS (extended X-ray absorption fine structure), inelastic X-ray scattering, Compton scattering and Moessbauer spectroscopy of crystalline, liquid or amorphous samples, are reported. This document gathers the abstracts of the presentations.

  20. High pressure and synchrotron radiation satellite workshop

    International Nuclear Information System (INIS)

    The workshop is dedicated to recent advances on science at high pressure at third generation synchrotron sources. A variety of experiments using synchrotron radiation techniques including X-ray diffraction, EXAFS (extended X-ray absorption fine structure), inelastic X-ray scattering, Compton scattering and Moessbauer spectroscopy of crystalline, liquid or amorphous samples, are reported. This document gathers the abstracts of the presentations

  1. High-Intensity Synchrotron Radiation Effects

    CERN Document Server

    Suetsugu, Y

    2016-01-01

    Various effects of intense synchrotron radiation on the performance of particle accelerators, especially for storage rings, are discussed. Following a brief introduction to synchrotron radiation, the basic concepts of heat load, gas load, electron emission, and the countermeasures against these effects are discussed.

  2. Funding problems threaten Middle East's synchrotron

    CERN Multimedia

    McCabe, H

    1999-01-01

    Scientists will tour the Middle East to try to raise support for the Synchrotron radiation for Experimental Science and Applications in the Middle East project. The plan is to dismantle and move a decommissioned synchrotron from Berlin to the Middle East where scientists of any nationality would be able to use it (3 paragraphs).

  3. Synchrotron Physics and Industry: new opportunities for technology transfer

    International Nuclear Information System (INIS)

    Full text: In 1979, with the opening in the UK of the world's first dedicated synchrotron light source, the SRS, experimental science in virtually every discipline underwent what amounted to a major revolution. The unique nature of synchrotron radiation, with its intensity, brightness, polarization, time structure and energy spectrum offer an unequalled probe of matter in all its states. The decades since have seen the development of a wide range of associated experimental techniques which harness the power of this radiation, including photoemission, EXAFS, spectroscopy, imaging and, of course, protein crystallography. These in turn have been applied to studies from surface science to molecular biology. The advances using synchrotron radiation throughout the 1980s and '90s naturally had a major impact on fundamental research, particularly in unraveling the structures of large proteins and in understanding the properties of semiconductors and surfaces. Much of this work could not have been accomplished without access to one of the world's increasing number of synchrotron facilities, of which there are now approaching 100. However, industrial awareness of the opportunities afforded by the use of synchrotron radiation was restricted to the handful of major multinational corporations, primarily in Europe, the USA and Japan, whose fundamental research staff had access. While there were major programmes in certain specific areas, such as X-ray lithography for semiconductor LSI fabrication, the general level of industrial involvement was low. But today, this is changing. In protein crystallography, for example, the use of synchrotron radiation in structure determination puts the 1PX' technique on the same level as NMR in terms of its routine utility. It has become an essential tool to drug designers in biopharmaceuticals, where access to the structural data is increasingly thought of almost as a service, rather than fundamental research. Pioneering work on medical imaging

  4. A Palmtop Synchrotron-like Radiation Source

    CERN Document Server

    Chen, Min; Luo, Ji; Liu, Feng; Sheng, Zheng-Ming; Zhang, Jie

    2015-01-01

    Synchrotron radiation sources are immensely useful tools for scientific researches and many practical applications. Currently, the state-of-the-art synchrotrons rely on conventional accelerators, where electrons are accelerated in a straight line and radiate in bending magnets or other insertion devices. However, these facilities are usually large and costly. Here, we propose a compact all-optical synchrotron-like radiation source based on laser-plasma acceleration either in a straight or in a curved plasma channel. With the laser pulse off-axially injected in a straight channel, the centroid oscillation of the pulse causes a wiggler motion of the whole accelerating structure including the trapped electrons, leading to strong synchrotron-like radiations with tunable spectra. It is further shown that a ring-shaped synchrotron is possible in a curved plasma channel. Due to the intense acceleration and bending fields inside plasmas, the central part of the sources can be made within palm size. With its potential...

  5. Protein Data Bank Depositions from Synchrotron Sources

    International Nuclear Information System (INIS)

    A survey and analysis of Protein Data Bank (PDB) depositions from international synchrotron radiation facilities, based on the latest released PDB entries, are reported. The results () show that worldwide, every year since 1999, more than 50% of the deposited X-ray structures have used synchrotron facilities, reaching 75% by 2003. In this web-based database, all PDB entries among individual synchrotron beamlines are archived, synchronized with the weekly PDB release. Statistics regarding the quality of experimental data and the refined model for all structures are presented, and these are analysed to reflect the impact of synchrotron sources. The results confirm the common impression that synchrotron sources extend the size of structures that can be solved with equivalent or better quality than home sources

  6. Medical applications with synchrotron radiation in Japan

    International Nuclear Information System (INIS)

    In Japan, various medical applications of synchrotron X-ray imaging, such as angiography, monochromatic X-ray computed tomography (CT), radiography and radiation therapy, are being developed. In particular, coronary arteriography (CAG) is quite an important clinical application of synchrotron radiation. Using a two-dimensional imaging method, the first human intravenous CAG was carried out at KEK in May 1996; however, further improvements of image quality are required in clinical practice. On the other hand, two-dimensional aortographic CAG revealed canine coronary arteries as clearly as those on selective CAG, and coronary arteries less than 0.2 mm in diameter. Among applications of synchrotron radiation to X-ray CT, phase-contrast X-ray CT and fluorescent X-ray CT are expected to be very interesting future applications of synchrotron radiation. For actual clinical applications of synchrotron radiation, a medical beamline and a laboratory are now being constructed at SPring-8 in Harima

  7. Effects, causing intensification of synchrotron radiaiton beams

    International Nuclear Information System (INIS)

    Possibility of intensification of synchrotron radiation beams in optical and ultraviolet spectrum range by shift of generation range of the output synchrotron radiation beams from circle sections of electron orbit to the magnetic field of gaps, separating sections of the accelerator electromagnets is discussed. The degree of manifestation of the considered effects in synchrotrons for 0.6 and 7.5 GeV energy is evaluated. The results of their experimental investigati.on in the optical beam of the 0.6 GeV synchrotron radiation are given. The results obtained show that beam intensity in the gap centre between the magnet sections increases 3.2 times. The structure of beam intensity distribution improves simultaneously and vertical direction of radiation increases approximately 2 times. A conclusion is made on applicability of the described method for beam intensification of synchrotron radiation

  8. Carbyne formation by synchrotron radiation

    CERN Document Server

    Kaito, C; Hanamoto, K; Sasaki, M; Kimura, S; Nakada, Tatsuya; Saitô, Y; Koike, C; Nakayama, Y

    2001-01-01

    Thin carbon films prepared by vacuum evaporation using the arc method were mounted on a standard electron microscope copper grid. They were irradiated by white synchrotron radiation (SR) beam by the use of cylindrical and toroidal mirrors. The irradiated film was examined using a high-resolution electron microscope. alpha and alpha+beta mixture carbyne crystals were grown in round and the elongated shapes. The round crystals were composed of 5-10 nm crystallites of a carbyne form. The elongated crystal grew into a single crystal 100 nm in size. The c-axes of both grown crystals were oblique to the film. The growth of the carbynes was discussed as being the result of nucleation due to graphite microcrystallites formed by SR beam irradiation.

  9. Workshop on surface and interface science at the ESRF

    International Nuclear Information System (INIS)

    The main aim of the workshop is to reflect the future of surface and interface research at the high brilliance synchrotron radiation source ESRF taking into account experimental facilities which are becoming available at new synchrotron radiation facilities in Europe. 6 sessions have been organized: 1) surface and interface research and synchrotron radiation - today and tomorrow -, 2) aspects of surface and interface research, 3) real surfaces and interfaces, 4) synchrotron techniques in surface and interface research, 5) new directions in surface and interface research, and 6) surface and interface science at ESRF. This document gathers the abstracts of the presentations

  10. Workshop on surface and interface science at the ESRF

    Energy Technology Data Exchange (ETDEWEB)

    Norris, C.; Stierle, A.; Kasper, N.; Dosch, H.; Schmidt, S.; Hufner, S.; Moritz, W.; Fedley, Ch.S.; Rossi, G.; Durr Hermann, A.; Rohlsberger, R.; Dalmas, J.; Oughaddou, H.; Leandri, Ch.; Gay, J.M.; Treglia, G.; Le Lay, G.; Aufray, B.; Bunk, O.; Johnson, R.L.; Frenken, J.W.M.; Lucas, C.A.; Bauer, G.; Zhong, Z.; Springholz, G.; Lechner, R.; Stang, J.; Schulli, T.; Metzger, T.H.; Holy, V.; Woodruff, D.P.; Dellera, C.; Zegenhagen, J.; Robinson, I.; Malachias, A.; Schulli, T.U.; Magalhaes-Paniago, R.; Stoffel, M.; Schmidt, O.G.; Boragno, C.; Buatier de Mongeot, F.; Valbusa, U.; Felici, R.; Yacoby, Y.; Bedzyk, M.J.; Van der Veen, J.F

    2004-07-01

    The main aim of the workshop is to reflect the future of surface and interface research at the high brilliance synchrotron radiation source ESRF taking into account experimental facilities which are becoming available at new synchrotron radiation facilities in Europe. 6 sessions have been organized: 1) surface and interface research and synchrotron radiation - today and tomorrow -, 2) aspects of surface and interface research, 3) real surfaces and interfaces, 4) synchrotron techniques in surface and interface research, 5) new directions in surface and interface research, and 6) surface and interface science at ESRF. This document gathers the abstracts of the presentations.

  11. Synchrotron applications to the earth sciences

    International Nuclear Information System (INIS)

    The earliest applications and development of conventional X-ray technologies at the beginning of the last century were strongly focused on earth science materials. Over the past 20 years minerals have continued to play a central role in the development of the new generations of synchrotron radiation techniques and the range of applications of synchrotron X-ray techniques to the study of the earth sciences has grown enormously. In this article we focus on the analytical possibilities arising from the application of synchrotron X-ray radiation as opposed to conventional cathode-tube based X-ray sources, using examples drawn from mineral characterisation and mineral processing

  12. Report of the Synchrotron Radiation Vacuum Workshop

    International Nuclear Information System (INIS)

    The Synchrotron Radiation Vacuum Workshop was held to consider two vacuum-related problems that bear on the design of storage rings and beam lines for synchrotron radiation facilities. These problems are gas desorption from the vacuum chamber walls and carbon deposition on optical components. Participants surveyed existing knowledge on these topics and recommended studies that should be performed as soon as possible to provide more definitive experimental data on these topics. This data will permit optimization of the final design of the Advanced Light Source (ALS) and its associated beam lines. It also should prove useful for other synchrotron radiation facilities as well

  13. In situ observation of surface reactions with synchrotron radiation induced semiconductor processes by infrared reflection absorption spectroscopy using buried metal layer substrates; Umekomi kinzokuso kiban wo mochiita sekigai hansha kyushu supekutoruho ni yoru hoshako reiki handotai process hanno no sonoba kansatsu

    Energy Technology Data Exchange (ETDEWEB)

    Yoshigoe, A.; Hirano, S. [The Graduate University for Advanced Studies, Yokohama (Japan); Mase, K.; Urisu, T. [Institute for Molecular Science, Aichi (Japan)

    1996-11-20

    It is known that infrared reflection absorption spectroscopy (IRAS) on semiconductor or insulator surfaces becomes practicable by using buried metal layer (BML) substrates, in which the metal thin film is buried order semiconductor or insulator films. In this work, IRAS has been measured for Langmuir-Blodgett films deposited on the BML substrate with SiO2/Al/Si(100) structure and the observed spectrum intensity has been quantitatively compared with the calculation assuming the ideal multilayer structure for the BML substrate. The BML-IRAS using CoSi2 has been adopted to the detection of SiHn on the Si (100) substrate during synchrotron radiation (SR) stimulated Si2H6 gas source molecular beam epitaxy. It has been found that SiH2 and SiH3 on the Si (100) surface are easily decomposed by SR, but SiH can`t be decomposed. From these experiments, it has been concluded that the BML-IRAS is an useful in situ observation technique for the photo-stimulated surface reactions. 26 refs., 9 figs.

  14. Methods for lipid nanostructure investigation at neutron and synchrotron sources

    Science.gov (United States)

    Kiselev, M. A.

    2011-03-01

    A lipid membrane is a main component of biological membranes. Contemporary bionanotechnologies use phospholipids and ceramides as basic components of drugs and cosmetic preparations. Phospholipids-based nanoparticles are used as drug carriers. Effective development of bionanotechnologies in Russia calls for creation of physical methods to diagnose the particle nanostructure which would be promising for application in pharmacology. Radiation with wavelengths of 1-10 Å is an adequate instrument for detecting the nanostructure of lipid bi- and monolayers. The review deals with methods that apply neutron scattering and synchrotron radiation for studying nanostructures of lipid membranes, phospholipid nanoparticles, and phospholipid monolayers on a water surface by techniques of diffraction, small-angle scattering, and reflectometry. The importance of the mutually complementary application of neutron and synchrotron radiation for solving urgent problems of membrane biophysics, microbiology, dermapharmacology, and bionanotechnologies is demonstrated by particular examples of studies of phospholipid membranes and ceramide-based membranes. The efficiency of development and application of new methods for solving urgent problems of biophysics is shown. The review is written on the basis of results obtained over the period of 1999-2010 at the Joint Institute for Nuclear Research (JINR) Laboratory of Neutron Physics in collaboration with the Pharmaceutical Departments of universities of France (Paris-Sud, Chatenay Malabry) and Germany (Martin Luther University, Halle). The experiments were performed at various European and Russian neutron and synchrotron sources.

  15. Quantitative X-ray microtomography with synchrotron radiation

    International Nuclear Information System (INIS)

    Synchrotron-radiation-based computed microtomography (SRμCT) is an established method for the examination of volume structures. It allows to measure the x-ray attenuation coefficient of a specimen three-dimensionally with a spatial resolution of about one micrometer. In contrast to conventional x-ray sources (x-ray tubes), the unique properties of synchrotron radiation enable quantitative measurements that do not suffer from beam-hardening artifacts. During this work the capabilities for quantitative SRμCT measurements have been further improved by enhancements that were made to the SRμCT apparatus and to the reconstruction chain. For high-resolution SRμCT an x-ray camera consisting of luminescent screen (x-ray phosphor), lens system, and CCD camera was used. A significant suppression of blur that is caused by reflections inside the luminescent screen could be achieved by application of an absorbing optical coating to the screen surface. It is shown that blur and ring artifacts in the tomographic reconstructions are thereby drastically reduced. Furthermore, a robust and objective method for the determination of the center of rotation in projection data (sinograms) is presented that achieves sub-pixel precision. By implementation of this method into the reconstruction chain, complete automation of the reconstruction process has been achieved. Examples of quantitative SRμCT studies conducted at the Hamburger Synchrotronstrahlungslabor HASYLAB at the Deutsches Elektronen-Synchrotron DESY are presented and used for the demonstration of the achieved enhancements. (orig.)

  16. Activity report of Synchrotron Radiation Laboratory 2001

    International Nuclear Information System (INIS)

    After moved from Tanashi to Kashiwa Campus in the spring of 2000, the Synchrotron Radiation Laboratory (SRL) has been promoting the High-brilliance Light Source project, Super SOR project, in cooperation with the nationwide user group as well as with the users of the University of Tokyo. In May of 2001, the project has met with a dramatic progress. The Ministry of Education, Science, Sports and Culture organized the Advisory Board and started to discuss the future synchrotron radiation facilities in EUV and SX regime in Japan. Based on extensive discussion, they proposed the new facility consisting of a 1.8 GeV storage ring of 3rd generation type. The University of Tokyo approved to construct the proposed facility in the Kashiwa campus. The plan is supported not only by researchers in academic institutions but also bio- and chemical-industries. We strongly hope the plan will be realized in near future. On the other hand, SRL maintains a branch laboratory in the Photon Factory (PF) High Energy Accelerator Research Organization (KEK) at Tsukuba with a Revolver undulator, two beamlines and three experimental stations (BL-18A, 19A and 19B), which are and fully opened to the outside users. In the fiscal year of 2001, the operation time of the beamlines was more than 5000 hours and the number of the users was about 200. The main scientific interests and activities in the SRL at KEK-PF are directed to the electronic structures of new materials with new transport, magnetic and optical properties. The electronic structures of solid surfaces and interfaces are also intensively studied by photoelectron spectroscopy and photoelectron microscopy. The accelerator group of SRL is carrying out research works of the accelerator physics and developing the accelerator-related technology, many parts of which will be directly applied to the new light source project. This report contains the activities of the staff members of SRL and users of the three beamlines in FY2001. The status of

  17. An assessment of research opportunities and the need for synchrotron radiation facilities

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-12-31

    The workshop focused on six topics, all of which are areas of active research: (1) speciation, reactivity and mobility of contaminants in aqueous systems, (2) the role of surfaces and interfaces in molecular environmental science, (3) the role of solid phases in molecular environmental science, (4) molecular biological processes affecting speciation, reactivity, and mobility of contaminants in the environment, (5) molecular constraints on macroscopic- and field-scale processes, and (6) synchrotron radiation facilities and molecular environmental sciences. These topics span a range of important issues in molecular environmental science. They focus on the basic knowledge required for understanding contaminant transport and fate and for the development of science-based remediation and waste management technologies. Each topic was assigned to a working group charged with discussing recent research accomplishments, significant research opportunities, methods required for obtaining molecular-scale information on environmental contaminants and processes, and the value of synchrotron x-ray methods relative to other methods in providing this information. A special working group on synchrotron radiation facilities was convened to provide technical information about experimental facilities at the four DOE-supported synchrotron radiation sources in the US (NSLS, SSRL, AS and UPS) and synchrotron- based methods available for molecular environmental science research. Similar information on the NSF-funded Cornell High Energy synchrotron Source (CHESS) was obtained after the workshop was held.

  18. An assessment of research opportunities and the need for synchrotron radiation facilities

    International Nuclear Information System (INIS)

    The workshop focused on six topics, all of which are areas of active research: (1) speciation, reactivity and mobility of contaminants in aqueous systems, (2) the role of surfaces and interfaces in molecular environmental science, (3) the role of solid phases in molecular environmental science, (4) molecular biological processes affecting speciation, reactivity, and mobility of contaminants in the environment, (5) molecular constraints on macroscopic- and field-scale processes, and (6) synchrotron radiation facilities and molecular environmental sciences. These topics span a range of important issues in molecular environmental science. They focus on the basic knowledge required for understanding contaminant transport and fate and for the development of science-based remediation and waste management technologies. Each topic was assigned to a working group charged with discussing recent research accomplishments, significant research opportunities, methods required for obtaining molecular-scale information on environmental contaminants and processes, and the value of synchrotron x-ray methods relative to other methods in providing this information. A special working group on synchrotron radiation facilities was convened to provide technical information about experimental facilities at the four DOE-supported synchrotron radiation sources in the US (NSLS, SSRL, AS and UPS) and synchrotron- based methods available for molecular environmental science research. Similar information on the NSF-funded Cornell High Energy synchrotron Source (CHESS) was obtained after the workshop was held

  19. To tilt or not to tilt: Correction of the distortion caused by inclined sample surfaces in low-energy electron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Sojka, Falko, E-mail: falko.sojka@uni-jena.de [Friedrich Schiller University Jena, Institute of Solid State Physics, Helmholtzweg 5, 07743 Jena (Germany); Meissner, Matthias; Zwick, Christian; Forker, Roman [Friedrich Schiller University Jena, Institute of Solid State Physics, Helmholtzweg 5, 07743 Jena (Germany); Vyshnepolsky, Michael; Klein, Claudius; Horn-von Hoegen, Michael [University of Duisburg-Essen, Department of Physics, Lotharstr. 1, 47057 Duisburg (Germany); Fritz, Torsten, E-mail: torsten.fritz@uni-jena.de [Friedrich Schiller University Jena, Institute of Solid State Physics, Helmholtzweg 5, 07743 Jena (Germany)

    2013-10-15

    Low-energy electron diffraction (LEED) is a widely employed technique for the structural characterization of crystalline surfaces and epitaxial adsorbates. For technical reasons the accessible reciprocal space is limited at a given primary electron energy E. This limitation may be overcome by sweeping E to observe higher diffraction orders decisively enhancing the quantitative examination. Yet, in many cases, such as molecular films with rather large unit cells, the adsorbate reflexes become less pronounced at energies high enough to observe substrate reflexes. One possibility to overcome this problem is an intentional inclination of the sample surface during the measurement at the expense of the quantitative interpretability of then severely distorted diffraction patterns. Here, we introduce a correction method for the axially symmetric distortion in LEED images of tilted samples. We provide experimental confirmation for micro-channel plate LEED and spot-profile analysis LEED instruments using the (7×7) reconstructed surface of a Si(111) single crystal as a reference sample. Finally, we demonstrate that the correction of this distortion considerably improves the quantitative analysis of diffraction patterns of adsorbates since substrate and adsorbate reflexes can be evaluated simultaneously. As an illustrative example we have chosen an epitaxial monolayer of 3,4,9,10-perylenetetracarboxylic dianhydride on Ag(111) that is known to form a commensurate superstructure. - Highlights: • We introduce a method to correct distortions in LEED patterns of tilted surfaces. • Higher diffraction orders unobservable at higher beam energies can be evaluated. • Our procedure makes LEED patterns of tilted samples quantitatively analyzable. • Experimental confirmation with SPA-LEED and MCP-LEED is presented. • The method is applied to PTCDA on Ag(111) confirming earlier literature values.

  20. Study of radioactive materials with synchrotron radiation

    International Nuclear Information System (INIS)

    Synchrotron radiation brings 3 major improvements compared to other X-ray sources usually used in laboratories. Its high brilliance permits the study of size-reduced samples, the low divergency of the beam gives the possibility to increase the angular resolution of the diffractometer and the spectrum of the X-photons which is continuous, allows the experimenter to chose a particular wavelength. Synchrotron radiation is becoming an important tool to investigate radioactive materials particularly burnt nuclear fuels. Zircon is the corrosion product that appears on fuel clad during irradiation, the use of synchrotron radiation with the right wavelength and a discerning incidence angle has clearly shown a crystallographic change of the zircon induced by heavy ion irradiation. X-ray fluorescence induced by synchrotron radiation can give information on fission products which were till then undetected because of the lack of sensibility of previous methods. (A.C.)

  1. Panel backs next-generation synchrotron

    CERN Multimedia

    Service, R F

    1999-01-01

    A key federal panel recommended continued research into development of a fourth-generation synchrotron. It would be capable of creating x-ray pulses billions of times more intense than current designs (1 page).

  2. Applications of synchrotron radiation in Biophysics

    International Nuclear Information System (INIS)

    A short introduction to the generation of the synchrotron radiation is made. Following, the applications of such a radiation in biophysics with emphasis to the study of the hemoglobin molecule are presented. (L.C.)

  3. Simulation of synchrotron motion with rf noise

    International Nuclear Information System (INIS)

    The theoretical formulation is described that is behind an algorithm for synchrotron phase-space tracking with rf noise and some preliminary simulation results of bunch diffusion under rf noise obtained by actual tracking

  4. Spain in quandry over French synchrotron

    CERN Multimedia

    Bosch, X

    2000-01-01

    The French government has invited Spain to participate in the funding and operation of its proposed synchrotron Soleil. This could result though in the end of Spanish scientists' hopes for their own machine (1 page).

  5. National synchrotron light source VUV storage ring

    Energy Technology Data Exchange (ETDEWEB)

    Blumberg, L.; Bittner, J.; Galayda, J.; Heese, R.; Krinsky, S.; Schuchman, J.; van Steenbergen, A.

    1979-01-01

    A 700 MeV electron storage ring designed for synchrotron radiation applications is described. Lattice and stability calculations are presented and the vacuum, correction and injection systems are discussed.

  6. Synchrotron radiation x-ray lithography

    International Nuclear Information System (INIS)

    Fine pattern fabrication technology has been supporting the progress in LSI integration. Synchrotron radiation X-ray lithography is considered the most promising path towards mass-production of LSIs a quarter micron or less in feature size. The present report first describes some fundamental characteristics of synchrotron radiation X-ray lithography, focusing on pattern replication methods, resolution (Fresnel diffraction, penumbral blur, mask contrast, and secondary electron range), process latitude, exposure field size, throughput, and overlay accuracy. The report also addresses test device fabrication conducted at NTT LSI Laboratories in Japan. Deep-submicron test device fabrication is carried out using synchrotron radiation lithography all of five exposure levels. The characteristics of the fabricated devices are found to be satisfactory. Synchrotron radiation X-ray lithography can potentially provide an excellent tool for fabricating fine patterns in the quarter micron range. (N.K.)

  7. Stanford Synchrotron Radiation Light Source (SSRL)

    Data.gov (United States)

    Federal Laboratory Consortium — The SSRL at SLAC National Accelerator Laboratory was built in 1974 to take and use for synchrotron studies the intense x-ray beams from the SPEAR storage ring that...

  8. Molecular photoemission studies using synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Truesdale, C.M.

    1983-04-01

    The angular distributions of photoelectrons and Auger electrons were measured by electron spectroscopy using synchrotron radiation. The experimental results are compared with theoretical calculations to interpret the electronic behavior of photoionization for molecular systems.

  9. Molecular photoemission studies using synchrotron radiation

    International Nuclear Information System (INIS)

    The angular distributions of photoelectrons and Auger electrons were measured by electron spectroscopy using synchrotron radiation. The experimental results are compared with theoretical calculations to interpret the electronic behavior of photoionization for molecular systems

  10. National Synchrotron Light Source annual report 1988

    Energy Technology Data Exchange (ETDEWEB)

    Hulbert, S.; Lazarz, N.; Williams, G. (eds.)

    1988-01-01

    This report discusses the experiment done at the National Synchrotron Light Source. Most experiments discussed involves the use of the x-ray beams to study physical properties of solid materials. (LSP)

  11. Synchrotrons are also devoted to society

    International Nuclear Information System (INIS)

    The ESRF and the SOLEIL synchrotrons are not only scientific instruments but also active players in the cultural and economic fields. This document gathers 6 short articles. The 2 first present the actions of SOLEIL and ESRS scientific teams towards the spreading of scientific knowledge in the public. The third article is dedicated to the uses of synchrotron radiation to the study of cultural objects to learn more about their fabrication, present state or the remedial actions that could be used to renovate them. The fourth and fifth articles present the contributions of ESRF and SOLEIL to the industrial world, in fact these contributions are not limited to the research field but also appear for quality assurance or the control of aging processes. Partnerships have been signed between both synchrotrons and enterprises to develop industrial products based on instrumentation or on the use of synchrotron radiation. The last article describes the procedure to have access to both facilities. (A.C.)

  12. Synchrotrons are also devoted to the society

    International Nuclear Information System (INIS)

    The ESRF and the SOLEIL synchrotrons are not only scientific instruments but also active players in the cultural and economic fields. This document gathers 6 short articles. The 2 first present the actions of SOLEIL and ESRS scientific teams towards the spreading of scientific knowledge in the public. The third article is dedicated to the uses of synchrotron radiation to the study of cultural objects to learn more about their fabrication, present state or the remedial actions that could be used to renovate them. The fourth and fifth articles present the contributions of ESRF and SOLEIL to the industrial world, in fact these contributions are not limited to the research field but also appear for quality assurance or the control of aging processes. Partnerships have been signed between both synchrotrons and enterprises to develop industrial products based on instrumentation or on the use of synchrotron radiation. The last article describes the procedure to have access to both facilities. (A.C.)

  13. Synchrotron radiation in inhomogeneous tokamak plasmas

    International Nuclear Information System (INIS)

    Synchrotron emission in a tokamak configuration with inhomogeneous plasma parameters is considered to investigate the effects of the temperature profile and vertical elongation on the radiation loss. Using the numerical solution of the transfer equation for ITER-like plasma parameters, several new results on the radiated energy in a Maxwellian plasma have been derived. In particular: (i) synchrotron loss is profile dependent, namely, at constant average thermal energy, the emitted radiation increases with the peak temperature, (ii) an analytical formula of the global loss in inhomogeneous tokamak plasmas with arbitrary vertical elongation is established, (iii) the maximum of the frequency emission spectrum is a linear function of the volume average temperature, (iiii) high frequency synchrotron radiation is entirely due to electrons with energy much greater than the thermal energy. The need for experimental investigations on synchrotron emission in present-day large tokamaks to determine the effect of reflections of the complex tokamak first wall is stressed

  14. Basic design for the synchrotron in the large synchrotron radiation facility, 1

    International Nuclear Information System (INIS)

    Synchrotron Radiation Facility Project Team in JAERI had tried to preliminarily design the injection system of Large Synchrotron Radiation Facility in the fiscal year 1988. Concentrating on the basic design for the booster synchrotron in this injection system, we describe the general method to design the separated function synchrotron which is used to accelerate high energy electrons or positrons. The content of this paper is founded on the physics of single particle motion. And in the next report we will discuss about the collective beam dynamics, the phenomena occurred during acceleration, and so on. (author)

  15. Early British synchrotrons, an informal history

    International Nuclear Information System (INIS)

    An historical account of the design and construction of early synchrotrons in the United Kingdom, based partly on personal reminiscences, is presented. Material is also drawn from archives at Birmingham and CERN. The document covers the period from plans for the world's first synchrotron at Malvern after the Second World War to work done at Harwell Laboratory for CERN in the period 1951-1953. (UK)

  16. Experimental demonstration of the KEK induction synchrotron

    International Nuclear Information System (INIS)

    Recent progress in the KEK induction synchrotron is presented. In the recent experiment, by using a newly developed induction acceleration system instead of radio-wave acceleration devices, a single proton bunch injected from the 500 MeV Booster ring and captured by the barrier bucket created by the induction step-voltages was accelerated to 6 GeV in the KEK proton synchrotron

  17. Commissioning experiences of the ALS booster synchrotron

    International Nuclear Information System (INIS)

    Installation of the ALS booster synchrotron proper was completed on April 30, 1991, and commissioning has just begun. Circulating beam around the booster was observed on the first day of operation, May 3, 1991. The beam was visible for about 400 turns. In this paper we describe the status and commissioning experience of the 1.5-GeV electron synchrotron accelerator. 14 refs., 2 figs., 4 tabs

  18. Optimized end station and operating protocols for reflection extended x-ray absorption fine structure (ReflEXAFS) investigations of surface structure at the European Synchrotron Radiation Facility beamline BM29

    International Nuclear Information System (INIS)

    The development of the capability to engineer the surface properties of materials to match specific requirements demands high quality surface characterization techniques. The ideal tool should provide chemically specific structural characterization as well as surface sensitivity and depth profiling. Ideally the characterization method should also be applicable to systems both with and without long range order. X-ray absorption spectroscopy fine structure, when using the standard transmission detection system, provides all this information with the significant exception of surface sensitivity. In contrast, by detecting the reflected instead of the transmitted beam, it encompasses all these requirements because when the incident beam impinges onto a sample surface at glancing angles, in conditions close to the total reflection, only the outermost regions of the system under study are sampled. Such a technique provides information about the local structure as a function of depth as well as thin layer structure in the case of layered samples. Although it is potentially the ideal tool to study surface modified materials, experimental difficulties have hampered its widespread use in the fields of surface and materials sciences. As a solution to the experimental challenges, we provide a detailed description of an appropriate experimental station, the sample requirements, the measuring protocols, and software routines needed to optimize the collection of the data. To illustrate the capabilities of the technique the results obtained for a model multilayer sample are presented and analyzed under the total external reflection approximation

  19. Laser-heating-based active optics for synchrotron radiation applications.

    Science.gov (United States)

    Yang, Fugui; Li, Ming; Gao, Lidan; Sheng, Weifan; Liu, Peng; Zhang, Xiaowei

    2016-06-15

    Active optics has attracted considerable interest from researchers in synchrotron radiation facilities because of its capacity for x-ray wavefront correction. Here, we report a novel and efficient technique for correcting or modulating a mirror surface profile based on laser-heating-induced thermal expansion. An experimental study of the characteristics of the surface thermal deformation response indicates that the power of a milliwatt laser yields a bump height as low as the subnanometer scale and that the variation of the spot size modulates the response function width effectively. In addition, the capacity of the laser-heating technique for free-form surface modulation is demonstrated via a one-dimensional surface correction experiment. The developed method is a promising new approach toward effective x-ray active optics coupled with at-wavelength metrology techniques. PMID:27304296

  20. Synchrotron irradiation study of hydrogenated silicon nitride film

    International Nuclear Information System (INIS)

    In the present study, the modifications in hydrogenated silicon nitride film upon synchrotron radiation (SR) illumination (using white light) are investigated by in situ soft x-ray reflectivity (XRR) measurements at Indus-l SR source. The illumination experiments are performed at 10 deg incidence angle at which the majority of incident radiation are restricted to ∼80 A depth. Due to irradiation the hydrogen bonds which are responsible for voids and network deformation, are more likely to break and pave the path for the formation of compact Si3N4 network. An increase in the film density and decrease in the film thickness is observed. In addition, the surface morphology changed significantly. Atomic force microscopy confirms the surface deformation. Out diffusion of hydrogen near the surface may be responsible for the surface modifications. (author)

  1. Laser-heating-based active optics for synchrotron radiation applications

    CERN Document Server

    Yang, Fugui; Zhang, Xiaowei

    2016-01-01

    Active optics has attracted considerable interest from researchers in synchrotron radiation facilities, because of its capacity for x-ray wavefront correction. Here, we report a novel and efficient technique for correcting or modulating a mirror surface profile based on laser-heating-induced thermal expansion. An experimental study of the characteristics of the surface thermal deformation response indicates that the power of a milliwatt laser yields a bump height as low as sub-nanometer scale, and that variation of the spot size modulates the response function width effectively. In addition, the capacity of the laser-heating technique for free-form surface modulation is demonstrated via a surface correction experiment. The developed method is a promising new approach towards effective x-ray active optics coupled with at-wavelength metrology techniques.

  2. Orbital control of Rashba spin orbit coupling in noble metal surfaces

    Science.gov (United States)

    Gong, Shi-Jing; Cai, Jia; Yao, Qun-Fang; Tong, Wen-Yi; Wan, Xiangang; Duan, Chun-Gang; Chu, J. H.

    2016-03-01

    Rashba spin orbit coupling (SOC) in noble metal surfaces is of great importance for the application of metal films in spintronic devices. By combining the density-functional theory calculations with our recently developed orbital selective external potential method, we investigate the Rashba SOC in the Shockley surface states of Au(111) and Ag(111). We find that the large Rashba SOC in the sp-character surface states of Au(111) is mainly contributed by the minor d-orbitals in the surface states. While for the sd-character surface states, although they are dominated by the d-orbitals, Rashba splitting is found to be rather small. Band structure analysis reveals that this is mainly because the sd-character surface states are well below the Fermi level and can be less influenced by the asymmetric surface potential. We demonstrate that the Rashba SOC in noble metal surfaces can be effectively manipulated by shifting the d-orbitals in the surface states, which can be physically implemented through surface decoration. Our investigation provides a deep understanding on Rashba SOC in noble metal surfaces and could be helpful to their applications in spintronic devices.

  3. Microfabrication of high quality polytetrafluoroethylene films by synchrotron radiation

    International Nuclear Information System (INIS)

    We deposited polytetrafluoroethylene (PTFE) thin films both from the PTFE target by using synchrotron radiation (SR) beam and from PTFE emulsion by spin-coat process. The X-ray diffraction analyses showed a sharp peak due to (1 0 0) PTFE crystalline part, and only C-F2 bonding was found in Fourier transform infrared spectrophotometer spectra. From electron spectroscopy for chemical analysis measurements, no impurities were found. The fabricated PTFE films were easily etched by SR beam on the limited area of the surface on a microscale through a suitably patterned mask

  4. Bimetallic nickel-cobalt nanosized layers supported on polar ZnO surfaces: metal-support interaction and alloy effects studied by synchrotron radiation X-ray photoelectron spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Law, Y.T.; Skála, T.; Pis, I.; Nehasil, V.; Vondráček, Martin; Zafeiratos, S.

    2012-01-01

    Roč. 116, č. 18 (2012), s. 10048-10056. ISSN 1932-7447 R&D Projects: GA MŠk(CZ) LC06058; GA ČR GD202/09/H041 Institutional support: RVO:68378271 Keywords : mc fuel-cell * hydrogen - production * oxide surfaces Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 4.814, year: 2012

  5. Synchrotron radiation applications in medical research

    International Nuclear Information System (INIS)

    The medical projects employing synchrotron radiation as discussed in this paper are, for the most part, still in their infancies and no one can predict the direction in which they will develop. Both the basic research and applied medical programs are sure to be advanced at the new facilities coming on line, especially the ESRF and Spring- 8. However, success is not guaranteed. There is a lot of competition from advances in conventional imaging with the development of digital angiography, computed tomography, functional magnetic resonance imaging and ultrasound. The synchrotron programs will have to provide significant advantages over these modalities in order to be accepted by the medical profession. Advances in image processing and potentially the development of compact sources will be required in order to move the synchrotron developed imaging technologies into the clinical world. In any event, it can be expected that the images produced by the synchrotron technologies will establish ''gold standards'' to be targeted by conventional modalities. A lot more work needs to be done in order to bring synchrotron radiation therapy and surgery to the level of human studies and, subsequently, to clinical applications

  6. Paraxial Green's functions in Synchrotron Radiation theory

    CERN Document Server

    Geloni, G; Schneidmiller, E; Yurkov, M; Geloni, Gianluca; Saldin, Evgeni; Schneidmiller, Evgeni; Yurkov, Mikhail

    2005-01-01

    This work contains a systematic treatment of single particle Synchrotron Radiation and some application to realistic beams with given cross section area, divergence and energy spread. Standard theory relies on several approximations whose applicability limits and accuracy are often forgotten. We begin remarking that on the one hand, a paraxial approximation can always be applied without loss of generality and with ultra relativistic accuracy. On the other hand, dominance of the acceleration field over the velocity part in the Lienard-Wiechert expressions is not always granted and constitutes a separate assumption, whose applicability is discussed. Treating Synchrotron Radiation in paraxial approximation we derive the equation for the slow varying envelope function of the Fourier components of the electric field vector. Calculations of Synchrotron Radiation properties performed by others showed that the phase of the Fourier components of the electric field vector differs from the phase of a virtual point sourc...

  7. Space-charge calculations in synchrotrons

    Energy Technology Data Exchange (ETDEWEB)

    Machida, S.

    1993-05-01

    One obvious bottleneck of achieving high luminosity in hadron colliders, such as the Superconducting Super Collider (SSC), is the beam emittance growth, due to space-charge effects in low energy injector synchrotrons. Although space-charge effects have been recognized since the alternating-gradient synchrotron was invented, and the Laslett tune shift usually calculated to quantify these effects, our understanding of the effects is limited, especially when the Laslett tune shift becomes a large fraction of the integer. Using the Simpsons tracking code, which we developed to study emittance preservation issues in proton synchrotrons, we investigated space-charge effects in the SSC Low Energy Booster (LEB). We observed detailed dependence on parameters such as beam intensity, initial emittance, injection energy, lattice function, and longitudinal motion. A summary of those findings, as well as the tracking technique we developed for the study, are presented.

  8. New extreme synchrotron BL Lac objects

    International Nuclear Information System (INIS)

    We report on the BeppoSAX observations of four 'extreme' BL Lacs, selected to have high synchrotron peak frequencies. All have been detected also in the PDS band. For 1ES 0120+340, PKS 0548-322 and H 2356-309 the spectrum is well fitted by a convex broken power-law, thus locating the synchrotron peak around 1-4 keV. 1ES 1426+428 presents a flat energy spectral index (αx=0.92) up to ∼100 keV, thus constraining the synchrotron peak to lie near or above that value. For their extreme properties, all sources could be strong TeV emitters

  9. Research on atmospheric corrosion of steel using synchrotron radiation

    International Nuclear Information System (INIS)

    Correlation between local structure around Cr in the protective rust layer on weathering steel and protective performance of the rust layer is presented as an example of corrosion research using synchrotron radiation which has recently been applied in various research fields as a useful tool. In addition, in situ observation of initial process of rust formation on steel is also mentioned. It was pointed out by considering the X-ray absorption fine structure spectra that the nanostructure of the protective rust layer on weathering steel primarily comprises of small Cr-goethite crystals containing surface adsorbed and/or intergranular CrOx3-2X complex anions. This CrOx3-2X explains the protective performance of the rust layer originated by dense aggregation of fine crystals with cation selectivity of the Cr-goethite. It is very advantageous to employ white X-rays for in situ observation of rusting process of a carbon steel covered with electrolyte thin films because rust structure might change very quickly. This in situ observation revealed the effect of ion species on the change in rust phase during wet/dry repeating. It can be said that application of synchrotron radiation on corrosion research is so useful to understand the nanostructure of surface oxides which closely relate to corrosion behavior of metals and alloys. (author)

  10. Synchrotron radiation in transactinium research report of the workshop

    Energy Technology Data Exchange (ETDEWEB)

    1992-11-01

    This report contains viewgraphs on the following topics. The advanced light source U8 undulator beamline, 20--300 eV; gas-phase actinide studies with synchrotron radiation; atomic structure calculations for heavy atoms; flux growth of single crystal uranium intermetallics: Extension to transuranics; x-ray absorption near-edge structure studies of actinide compounds; surface as a new stage for studying actinides: Theoretical study of the surface electronic structure of uranium; magnetic x-ray scattering experiments at resonant energies; beamline instruments for radioactive materials; the search for x-ray absorption magnetic circular dichroism in actinide materials: preliminary experiments using UFe{sub 2} and U-S; the laser plasma laboratory light source: a source of preliminary transuranic data; electron spectroscopy of heavy fermion actinide materials; study of thin layers of actinides. Present status and future use of synchrotron radiation; electronic structure and correlated-electron theory for actinide materials; and heavy fermion and kondo phenomena in actinide materials.

  11. Synchrotron radiation in transactinium research report of the workshop

    Energy Technology Data Exchange (ETDEWEB)

    1992-11-01

    This report contains viewgraphs on the following topics. The advanced light source U8 undulator beamline, 20--300 eV; gas-phase actinide studies with synchrotron radiation; atomic structure calculations for heavy atoms; flux growth of single crystal uranium intermetallics: Extension to transuranics; x-ray absorption near-edge structure studies of actinide compounds; surface as a new stage for studying actinides: Theoretical study of the surface electronic structure of uranium; magnetic x-ray scattering experiments at resonant energies; beamline instruments for radioactive materials; the search for x-ray absorption magnetic circular dichroism in actinide materials: preliminary experiments using UFe[sub 2] and U-S; the laser plasma laboratory light source: a source of preliminary transuranic data; electron spectroscopy of heavy fermion actinide materials; study of thin layers of actinides. Present status and future use of synchrotron radiation; electronic structure and correlated-electron theory for actinide materials; and heavy fermion and kondo phenomena in actinide materials.

  12. SUNY beamline facilities at the National Synchrotron Light Source (Final Report)

    International Nuclear Information System (INIS)

    The DOE sponsored SUNY synchrotron project has involved close cooperation among faculty at several SUNY campuses. A large number of students and postdoctoral associates have participated in its operation which was centered at the X3 beamline of the National Synchrotron Light Source at Brookhaven National Laboratory. Four stations with capabilities for Small Angle Scattering, Single Crystal and Powder and Surface diffraction and EXAFS were designed and operated with capability to perform experiments at very low as well as elevated temperatures and under high vacuum. A large amount of cutting-edge science was performed at the facility, which in addition provided excellent training for students and postdoctoral scientists in the field

  13. Characterizing laser fusion welded aluminum using synchrotron x-ray microtomography

    International Nuclear Information System (INIS)

    Preliminary research into the application of high power Nd-YAG lasers for welding indicate a dependency of the occurrence of weld discontinuities on processing parameters such as pulse duty cycle, travel speed, etc. The size and distribution of weld features have been characterized using synchrotron microtomography, using facilities at the National Synchrotron Light Source. The ability of this technique to image defects such as gross and minor porosity, and centerline cracking, enables a metrology of interior surfaces which cannot be provided by metallurgical sectioning techniques alone

  14. Synchrotron X-ray CT characterization of titanium parts fabricated by additive manufacturing. Part I. Morphology.

    Science.gov (United States)

    Scarlett, Nicola Vivienne Yorke; Tyson, Peter; Fraser, Darren; Mayo, Sheridan; Maksimenko, Anton

    2016-07-01

    Synchrotron X-ray tomography has been applied to the study of titanium parts fabricated by additive manufacturing (AM). The AM method employed here was the Arcam EBM(®) (electron beam melting) process which uses powdered titanium alloy, Ti64 (Ti alloy with approximately 6%Al and 4%V), as the feed and an electron beam for the sintering/welding. The experiment was conducted on the Imaging and Medical Beamline of the Australian Synchrotron. Samples were chosen to examine the effect of build direction and complexity of design on the surface morphology and final dimensions of the piece. PMID:27359150

  15. SUNY beamline facilities at the National Synchrotron Light Source (Final Report)

    Energy Technology Data Exchange (ETDEWEB)

    Coppens, Philip

    2003-06-22

    The DOE sponsored SUNY synchrotron project has involved close cooperation among faculty at several SUNY campuses. A large number of students and postdoctoral associates have participated in its operation which was centered at the X3 beamline of the National Synchrotron Light Source at Brookhaven National Laboratory. Four stations with capabilities for Small Angle Scattering, Single Crystal and Powder and Surface diffraction and EXAFS were designed and operated with capability to perform experiments at very low as well as elevated temperatures and under high vacuum. A large amount of cutting-edge science was performed at the facility, which in addition provided excellent training for students and postdoctoral scientists in the field.

  16. Synchrotron environmental laboratory (SUL) at Anka

    International Nuclear Information System (INIS)

    A research facility dedicated to environmental/geochemical research, the Synchrotron Environmental Laboratory (SUL), is planned to be installed and operated at ANKA. ANKA is the new synchrotron facility at the Research Centre Karlsruhe (FZK), Karlsruhe, Germany. ANKA is now in commissioning and planning operations for the fall of 2000. As the Institute for Nuclear Waste Disposal (INE) at FZK conducts a vigorous synchrotron-based research programme, INE was instrumental in the original impetus for installing such a facility at ANKA. These research activities at INE concentrate on actinide speciation in nuclear waste forms, geological media and geochemical model systems. In order for INE to direct their synchrotron research activities to ANKA, equipment and licensing required for performing experiments on actinide-containing samples is required. One great advantage of performing experiments on actinide-containing samples at ANKA is that the INE radiological laboratories lie in the near vicinity of the facility. This will minimise transport hazards and costs and allow experiments to be performed on samples whose characteristics may change with time. Experiments on radioactive samples with activities below the exemption level, according to German regulations, will be possible at ANKA at the start of operations. Licensing for work on higher levels of activity will be applied for in the future. The decades of experience in radiological work at FZK will facilitate development of procedure and equipment as prerequisites to licensing. A consortium of synchrotron radiation-user groups with environmental research interests has specified their requirements and needs for this facility. This scientific case serves as the foundation for the SUL design and is the basis for an application for federal funding. The SUL design reflects the heterogeneity and complexity of challenges facing researchers in the environmental/geochemical sciences. X-ray absorption fine structure (XAFS

  17. Basic technology of synchrotron power supply

    International Nuclear Information System (INIS)

    The thyristor power supply for a synchrotron magnet system is described. An analysis of the magnet strings, power electronics and control system is carried out with a bird's-eye view, however the fundamental description is appeared. It assumes a student and an engineer in fields concepts, which can be the electronics designing in related fields, and a background in Laplas transforms. It presents an example of power supply, which is developed for the synchrotron- cooler ring TARN II at Institute for Nuclear Study, Univ. of Tokyo. (author)

  18. Bunch heating by coherent synchrotron radiation

    International Nuclear Information System (INIS)

    The authors discuss here effects which define the steady-state rms energy spread of a microbunch in a storage ring. It is implied that the longitudinal microwave instability is controlled by low α lattice. In this case the coherent synchrotron radiation, if exists, may be the main factor defining the bunch temperature. Another effect comes from the fact that a nonlinear momentum compaction of such lattices makes Haissinskii equation not applicable, and the coherent synchrotron radiation may effect not only bunch lengthening but the energy spread as well

  19. 12 Experimental Techniques at Synchrotron Lightsource Beamlines

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Peter L [US Department of Energy Office of Science Office Basic Energy Sciences; Rhyne, James J [US Department of Energy Office of Science Office of Basic Energy Sciences

    2015-01-01

    The unique properties of synchrotron radiation are its continuous spectrum, high flux and brightness, and high coherence, which make it an indispensable tool in the exploration of matter. The wavelengths of the emitted photons span a range of dimensions from the atomic level to biological cells, thereby providing incisive probes for advanced research in materials science, physical and chemical sciences, metrology, geosciences, environmental sciences, biosciences, medical sciences, and pharmaceutical sciences. The features of synchrotron radiation are especially well matched to the needs of nanoscience.

  20. Atomic collision experiments using pulsed synchrotron radiation

    International Nuclear Information System (INIS)

    High intensity and continuous nature of the synchrotron radiation are the properties that are fundamentally important for studies of some atomic collision experiments, and many processes have been investigated by using these characteristics. However, so far the property that the radiation is highly polarized and pulsed in time has not been exploited significantly in atomic physics. As an example of the atomic processes relevant to such polarized and pulsed features of the synchrotron radiation, collisions involving optically-allowed excited atoms and molecules will be presented. (author)

  1. Berkeley Lab's ALS generates femtosecond synchrotron radiation

    International Nuclear Information System (INIS)

    A Lawrence Berkeley National Laboratory team has succeeded in generating 300 fs pulses of synchrotron radiation at the ALS synchrotron radiation machine. Although this proof-of-principle experiment made use of visible light on a borrowed beamline, the laser 'time-slicing' technique at the heart of the demonstration will soon be applied in a new bend-magnet beamline that was designed specially for the production of femtosecond pulses of X-rays to study long-range and local order in condensed matter with ultrafast time resolution. An undulator beamline based on the same technique has been proposed that will dramatically increase the flux and brightness

  2. Outline of micro-XAFS system installed at the synchrotron soft X-ray beamline

    International Nuclear Information System (INIS)

    The present report summarizes the outline and details of synchrotron soft X-ray micro-XAFS (X-ray absorption fine structure) system installed at the synchrotron beamline (BL-27A) of the Photon Factory (PF), High Energy Accelerator Research Organization (KEK). The system was installed for the purpose of measuring morphology, element-selective and chemical-state-selective mappings of solid surfaces at micrometer or nanometer scale. In this report, the detailed outlines, specification, and operation manual are firstly described. Then the experimental data about the observations on Si micro-pattern and estimation of spatial resolution using ultraviolet light are presented. Preliminary experimental results for chemical-state-selective mapping of Si/SiO2 micro-patterns using synchrotron radiation are also presented. (author)

  3. Preliminar plan of a machine for the synchrotron radiation production

    International Nuclear Information System (INIS)

    A preliminar plan, with all the technical specifications, for the construction of a machine for the synchrotron radiation production to be done by the National Synchrotron Radiation Laboratory in Brazil is presented. (L.C.)

  4. Quantitative X-ray microtomography with synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Donath, T. [GKSS-Forschungszentrum Geesthacht GmbH (Germany). Inst. fuer Materialforschung

    2007-07-01

    Synchrotron-radiation-based computed microtomography (SR{sub {mu}}CT) is an established method for the examination of volume structures. It allows to measure the x-ray attenuation coefficient of a specimen three-dimensionally with a spatial resolution of about one micrometer. In contrast to conventional x-ray sources (x-ray tubes), the unique properties of synchrotron radiation enable quantitative measurements that do not suffer from beam-hardening artifacts. During this work the capabilities for quantitative SR{sub {mu}}CT measurements have been further improved by enhancements that were made to the SR{sub {mu}}CT apparatus and to the reconstruction chain. For high-resolution SR{sub {mu}}CT an x-ray camera consisting of luminescent screen (x-ray phosphor), lens system, and CCD camera was used. A significant suppression of blur that is caused by reflections inside the luminescent screen could be achieved by application of an absorbing optical coating to the screen surface. It is shown that blur and ring artifacts in the tomographic reconstructions are thereby drastically reduced. Furthermore, a robust and objective method for the determination of the center of rotation in projection data (sinograms) is presented that achieves sub-pixel precision. By implementation of this method into the reconstruction chain, complete automation of the reconstruction process has been achieved. Examples of quantitative SR{sub {mu}}CT studies conducted at the Hamburger Synchrotronstrahlungslabor HASYLAB at the Deutsches Elektronen-Synchrotron DESY are presented and used for the demonstration of the achieved enhancements. (orig.)

  5. Surface electron density models for accurate ab initio molecular dynamics with electronic friction

    Science.gov (United States)

    Novko, D.; Blanco-Rey, M.; Alducin, M.; Juaristi, J. I.

    2016-06-01

    Ab initio molecular dynamics with electronic friction (AIMDEF) is a valuable methodology to study the interaction of atomic particles with metal surfaces. This method, in which the effect of low-energy electron-hole (e-h) pair excitations is treated within the local density friction approximation (LDFA) [Juaristi et al., Phys. Rev. Lett. 100, 116102 (2008), 10.1103/PhysRevLett.100.116102], can provide an accurate description of both e-h pair and phonon excitations. In practice, its applicability becomes a complicated task in those situations of substantial surface atoms displacements because the LDFA requires the knowledge at each integration step of the bare surface electron density. In this work, we propose three different methods of calculating on-the-fly the electron density of the distorted surface and we discuss their suitability under typical surface distortions. The investigated methods are used in AIMDEF simulations for three illustrative adsorption cases, namely, dissociated H2 on Pd(100), N on Ag(111), and N2 on Fe(110). Our AIMDEF calculations performed with the three approaches highlight the importance of going beyond the frozen surface density to accurately describe the energy released into e-h pair excitations in case of large surface atom displacements.

  6. Proceedings of the workshop on applications of synchrotron radiation to trace impurity analysis for advanced silicon processing

    Energy Technology Data Exchange (ETDEWEB)

    Laderman, S [Integrated Circuits Business Div., Hewlett Packard Co., Palo Alto, CA (United States); Pianetta, P [Stanford Linear Accelerator Center, Menlo Park, CA (United States)

    1993-03-01

    Wafer surface trace impurity analysis is essential for development of competitive Si circuit technologies. Today's grazing incidence x-ray fluorescence techniques with rotating anodes fall short of requirements for the future. Hewlett Packard/Toshiba experiments indicate that with second generation synchrotron sources such as SSRL, the techniques can be extended sufficiently to meet important needs of the leading edge Si circuit industry through nearly all of the 1990's. This workshop was held to identify people interested in use of synchrotron radiation-based methods and to document needs and concerns for further development. Viewgraphs are included for the following presentations: microcontamination needs in silicon technology (M. Liehr), analytical methods for wafer surface contamination (A. Schimazaki), trace impurity analysis of liquid drops using synchrotron radiation (D. Wherry), TRXRF using synchrotron sources (S. Laderman), potential role of synchrotron radiation TRXRF in Si process R D (M. Scott), potenital development of synchrotron radiation facilities (S. Brennan), and identification of goals, needs and concerns (M. Garner).

  7. Atomic physics research with synchrotron radiation

    International Nuclear Information System (INIS)

    Applications of synchrotron radiation to research in high-energy atomic physics are summarized. These lie in the areas of photoelectron spectrometry, photon scattering, x-ray absorption spectroscopy, time-resolved measurements, resonance spectroscopy and threshold excitation, and future, yet undefined studies

  8. The Synchrotron Radiation for Steel Research

    Directory of Open Access Journals (Sweden)

    Piyada Suwanpinij

    2016-01-01

    Full Text Available The synchrotron X-ray radiation is a great tool in materials characterization with several advantageous features. The high intensity allows clear interaction signals and high energy of X-ray yields higher sampling volume. The samples do not need extra preparation and the microstructure is therefore not affected. With the tunability of the X-ray energy, a large range of elements and features in the samples can be investigated by different techniques, which is a significant difference between a stand-alone X-ray tube and synchrotron X-ray. Moreover, any experimental equipment can be installed through which the synchrotron beam travels. This facilitates the so-called in situ characterization such as during heat treatment, hot deformation, chemical reaction or welding. Although steel which possesses rather high density requires very high energy X-ray for large interaction volume, lower energy is still effective for the investigation of local structure of nanoconstituents. This work picks up a couple examples employing synchrotron X-ray for the characterization of high strength steels. The first case is the quantification of precipitates in high strength low alloyed (HSLA steel by X-ray absorption spectroscopy. The other case is the in situ X-ray diffraction for phase fraction and carbon partitioning in multiphase steels such as transformation induced plasticity (TRIP steel.

  9. Synchrotron radiation and free electron laser activities in Novosibirsk

    International Nuclear Information System (INIS)

    The results of studies realized in the Siberian synchrotron radiation centre within the frameworks of wide program of synchrotron radiation and free electron laser research are summarized. The technical information on the VEPP-2M, VEPP-3 and VEPP-4M storage rings used as synchrotron radiation sources is given. 10 refs.; 8 figs.; 12 tabs

  10. Basic design for the RF system of the synchrotron in the large synchrotron radiation facility (SPring-8)

    International Nuclear Information System (INIS)

    The large synchrotron radiation facility (SPring-8) is planned to be built at Nishiharima in Hyogo-ken. This paper describes basic designs, its philosophy and specifications of the ratio frequency system in the synchrotron. (author)

  11. In situ observation of rolling contact fatigue cracks by laminography using ultrabright synchrotron radiation

    OpenAIRE

    Y. Nakai; D. Shiozawa,; Kikuchi, S; Sato, K.; T. Obama; Makino, T; Y. Neishi

    2015-01-01

    In rolling contact fatigue (RCF), cracks usually initiate from inclusions beneath the surface and propagate to the contact surface. In the present study, synchrotron radiation computed laminography (SRCL) imaging was performed to observe flaking defects during the RCF of a high-strength steel. Specially fabricated inclusion-rich steel plate specimens were employed in the experiments. For the in situ observation of crack propagation, a compact RCF testing machine was developed, and...

  12. Study on defect structure of silicon monocrystal wafers using synchrotron radiation

    International Nuclear Information System (INIS)

    The results of investigation on possibility of determining structural perfection of surface monocrystal layers by means of topography in Bragg geometry using synchrotron radiation are presented. The method is based on the primary extinction phenomenon and allows one with the help of topograms obtained in different reflection orders in a wide wave length range to determine the picture of surface layer defects distribution in the depth from some to tens of microns

  13. Computerized microtomography using synchrotron radiation from the NSLS [National Synchrotron Light Source

    International Nuclear Information System (INIS)

    Results of microtomography experiments that employ filtered radiation from the National Synchrotron Light Source X-26 Microprobe beam line are presented. These experiments have yielded images of a freeze-dried caterpillar with a spatial resolution of the order of 30 μm and show that the limit on the spatial resolution with the present apparatus will be 1 to 10 μm. Directions for improvement in synchrotron microtomography techniques and some possible applications are discussed. 14 refs., 3 figs

  14. Synchrotron X-Ray Study of Melting in Submonolayer Ar and other Rare-Gas Films on Graphite

    DEFF Research Database (Denmark)

    McTague, J. P.; Als-Nielsen, Jens Aage; Bohr, Jakob;

    1982-01-01

    Synchrotron x-ray diffraction studies of the (10) peak of Ar on the (001) surface of ZYX graphite show a sharp but continuous broadening of the Bragg peak with increasing temperature. Below a coverage of ∼ 1 Ar atom per six surface carbon atoms (ρ=1) the onset of this transition occurs at a...

  15. The profile of the electron beam in the PTB synchrotron, and its influence on radiometric measurements with synchrotron radiation

    International Nuclear Information System (INIS)

    A simple method is described to determine the beam profile in an electron synchrotron; the measured results are compared with calculated values. Moreover, the influence of synchrotron- and betatron-oscillations on synchrotron radiation measurements is discussed, and a method is given to correct this. (orig.)

  16. 50 years of synchrotrons. Early synchrotrons in Britain, and early work for CERN. - The CERN synchrotrons. Lectures

    International Nuclear Information System (INIS)

    In the first report, 'Early synchrotrons in Britain, and early work for CERN', John Lawson gives an extended account of the material presented at the John Adams lecture, and at the same time a revised and shortened version of RAL report 97-011, which contains fuller archival references and notes. During the period covered by this report there was extensive work in Russia, where the principle of phase stability had been discovered in 1944 by Veksler. Unfortunately, all experimental work was kept secret until Veksler's talk at the first 'Atoms for Peace' conference at Geneva in August 1955. In the second lecture, 'The CERN Synchrotrons', Giorgio Brianti outlines the history of alternating-gradient synchrotrons from 1953/54 until today. In preparing this lecture he was confronted with a vast amount of material, while the time at his disposal was not even one minute per year, implying a time compression factor close to one million. Therefore, he had to exercise drastic choices, which led him to concentrate on CERN hadron synchrotrons and colliders and leave aside the Large Electron-Positron storage ring (LEP). Indeed, LEP was the subject of the John Adams Memorial Lecture in 1990, and it may be treated again in the future in connection with its energy upgrade. Even with these severe limitations, it was impossible to do justice to the number and variety of events and to the ingenuity of the people who have carved the history of CERN and of particle physics on the magnets, radiofrequency cavities, vacuum etc., and on the record performance of our machines. (orig./WL)

  17. Materials research and beam line operation utilizing NSLS [National Synchrotron Light Source]: Progress report

    International Nuclear Information System (INIS)

    MATRIX is a group of scientists who have common interests in utilizing x-ray synchrotron radiation for materials research. This group has developed a specialized beam line (X-18A) for x-ray scattering studies at the National Synchrotron Light Source (NSLS). The beam line was designed to optimize experimental conditions for diffuse scattering and surface/interface studies. An extension of diffuse scattering to provide better quantitative data has been shown as well as a unique application to the solution of the phase problem. In the x-ray surface scattering area the first reported experiment to illustrate the capabilities for studying monolayers on water was performed. Current beam line upgrade projects are also described. In addition to a change to a UHV system and improvements dictated by operational experience, two new systems are described, a unique small angle scattering chamber (SAXS) for dynamic studies of nucleation and growth and a surface scattering chamber. 5 figs

  18. Supramolecular architectures and nanostructures at metal surfaces

    Science.gov (United States)

    Barth, J. V.; Weckesser, J.; Lin, N.; Dmitriev, A.; Kern, K.

    The controlled formation of non-covalent bonds (H-bonding, metal-ligand interactions) is the key ingredient for the fabrication of supramolecular architectures and nanostructures. Upon deposition of molecular building blocks at well-defined surfaces, this issue can be directly addressed. Scanning tunneling microscopy observations are presented, which provide insight into the interaction of functional groups on metal substrates at the molecular level. In particular, carboxylic acids were employed: (4-[(pyrid-4-yl-ethynyl)]-benzoic acid (PEBA), 4-[trans-2-(pyrid-4-yl-vinyl)]-benzoic acid (PVBA) and trimesic acid (1,3,5-benzenetricarboxylic acid, TMA), which could be stabilized in a flat geometry at the surface. By choosing the appropriate substrate material and symmetry, the sensitive balance of intermolecular and molecule-substrate interactions can be tuned to obtain well-defined supramolecular architectures and nanostructures. The head-to-tail hydrogen bonding of the related rod-like species PEBA and PVBA stabilizes molecular rows on Ag(111). The subtle difference in the molecular geometries is reflected in the lateral ordering: While 2-D islanding is encountered with PEBA, 1-D nanogratings of supramolecular chiral H-bonded twin chains evolve for PVBA. The threefold symmetry of TMA in conjunction with the self-complementarity of its exodentate groups accounts for the formation of H-bonded honeycomb networks on Cu(100) at low temperatures. Metal-ligand interactions were probed with PVBA and TMA at Cu surfaces at ambient temperature. Deprotonation of the carboxyl moiety takes place, which readily interacts with Cu adatoms evaporated from step edges. This leads to a head-to-head pairing of PVBA on Cu(111) and cloverleaf-shaped Cu-TMA coordination compounds on Cu(001).

  19. Synchrotron radiation. Basics, methods and applications

    Energy Technology Data Exchange (ETDEWEB)

    Mobilio, Settimio; Meneghini, Carlo [Roma Tre Univ. (Italy). Dept. of Science; Boscherini, Federico (ed.) [Bologna Univ. (Italy). Dept. of Physics and Astronomy

    2015-02-01

    Synchrotron radiation is today extensively used for fundamental and applied research in many different fields of science. Its exceptional characteristics in terms of intensity, brilliance, spectral range, time structure and now also coherence pushed many experimental techniques to previously un-reachable limits, enabling the performance of experiments unbelievable only few years ago. The book gives an up-to-date overview of synchrotron radiation research today with a view to the future, starting from its generation and sources, its interaction with matter, illustrating the main experimental technique employed and provides an overview of the main fields of research in which new and innovative results are obtained. The book is addressed to PhD students and young researchers to provide both an introductory and a rather deep knowledge of the field. It will also be helpful to experienced researcher who want to approach the field in a professional way.

  20. Indus synchrotron source: A national facility

    International Nuclear Information System (INIS)

    Indus Synchrotron Radiation complex at Raja Ramanna Centre for Advanced Technology at Indore, India houses two synchrotron radiation sources: Indus-1 and Indus-2 respectively. Indus-1 is a 450 MeV source emitting in VUV and soft x-ray region and operating at 100 mA since 1990 and Indus-2, designed for 2.5 GeV, 300 mA and is currently operating at 2 GeV and 100 mA. Indus-1 has five operational beamlines while Indus-2 has six beamlines installed and operational. Several materials research related problems have been investigated using the reflectivity and photo-electron spectroscopy beamlines at Indus-1 and also the beamlines at Indus-2. Here we will report the current status of both these sources and discuss a few of our studies carried out using these beamlines.

  1. Synchrotron Applications of High Magnetic Fields

    International Nuclear Information System (INIS)

    This workshop aims at discussing the scientific potential of X-ray diffraction and spectroscopy in magnetic fields above 30 T. Pulsed magnetic fields in the range of 30 to 40 T have recently become available at Spring-8 and the ESRF (European synchrotron radiation facility). This document gathers the transparencies of the 6 following presentations: 1) pulsed magnetic fields at ESRF: first results; 2) X-ray spectroscopy and diffraction experiments by using mini-coils: applications to valence state transition and frustrated magnet; 3) R5(SixGe1-x)4: an ideal system to be studied in X-ray under high magnetic field?; 4) high field studies at the Advanced Photon Source: present status and future plans; 5) synchrotron X-ray diffraction studies under extreme conditions; and 6) projects for pulsed and steady high magnetic fields at the ESRF

  2. Impact parameter profile of synchrotron radiation

    CERN Document Server

    Artru, X

    2005-01-01

    The horizontal impact parameter profile of synchrotron radiation, for fixed vertical angle of the photon, is calculated. This profile is observed through an astigmatic optical system, horizontally focused on the electron trajectory and vertically focused at infinity. It is the product of the usual angular distribution of synchrotron radiation, which depends on the vertical angle $\\psi$, and the profile function of a caustic staying at distance $\\bcl = (\\gamma^{-2} + \\psi^2) \\RB/2 $ from the orbit circle, $\\RB$ being the bending radius and $\\gamma$ the Lorentz factor. The {\\it classical impact parameter} $\\bcl$ is connected to the Schott term of radiation damping theory. The caustic profile function is an Airy function squared. Its fast oscillations allow a precise determination of the horizontal beam width.

  3. Synchrotron Mossbauer Spectroscopy of powder samples

    International Nuclear Information System (INIS)

    Synchrotron Mossbauer Spectroscopy, SMS, is an emerging technique that allows fast and accurate determination of hyperfine field parameters similar to conventional Mossbauer spectroscopy with radioactive sources. This new technique, however, is qualitatively different from Mossbauer spectroscopy in terms of equipment, methodology, and analysis to warrant a new name. In this paper, the authors report on isomer shift and quadrupole splitting measurements of Mohr's salt, Fe(NH4)2(SO4)2·6H2O for demonstration purposes. Theoretical calculations were performed and compared to experiments both in energy and time domain to demonstrate the influence of thickness distribution and preferential alignment of powder samples. Such measurements may prove to be useful when the data collection times are reduced to few seconds in the third generation, undulator based synchrotron radiation sources

  4. Diffusive synchrotron radiation from extragalactic jets

    CERN Document Server

    Fleishman, G D

    2006-01-01

    Flattenings of nonthermal radiation spectra observed from knots and interknot locations of the jets of 3C273 and M87 in UV and X-ray bands are discussed within modern models of magnetic field generation in the relativistic jets. Specifically, we explicitly take into account the effect of the small-scale random magnetic field, probably present in such jets, which gives rise to emission of Diffusive Synchrotron Radiation, whose spectrum deviates substantially from the standard synchrotron spectrum, especially at high frequencies. The calculated spectra agree well with the observed ones if the energy densities contained in small-scale and large-scale magnetic fields are comparable. The implications of this finding for magnetic field generation, particle acceleration, and jet composition are discussed.

  5. Electronic properties of physisorbed helium

    International Nuclear Information System (INIS)

    This thesis deals with electronic excitations of helium physisorbed on metal substrates. It is studied to what extent the electronic properties change compared to the gas phase due to the increased helium density and the proximity of the metal. Furthermore, the influence of different substrate materials is investigated systematically. To this end, up to two helium layers were adsorbed onto Ru (001), Pt (111), Cu (111), and Ag (111) surfaces in a custom-made cryostat. These samples were studied spectroscopically using synchrotron radiation and a time-of-flight detector. The experimental results were then analyzed in comparison with extensive theoretical model calculations.

  6. Electronic properties of physisorbed helium

    Energy Technology Data Exchange (ETDEWEB)

    Kossler, Sarah

    2011-09-22

    This thesis deals with electronic excitations of helium physisorbed on metal substrates. It is studied to what extent the electronic properties change compared to the gas phase due to the increased helium density and the proximity of the metal. Furthermore, the influence of different substrate materials is investigated systematically. To this end, up to two helium layers were adsorbed onto Ru (001), Pt (111), Cu (111), and Ag (111) surfaces in a custom-made cryostat. These samples were studied spectroscopically using synchrotron radiation and a time-of-flight detector. The experimental results were then analyzed in comparison with extensive theoretical model calculations.

  7. Structural analysis with high brilliance synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Ohno, Hideo [Japan Atomic Energy Research Inst., Kamigori, Hyogo (Japan). Kansai Research Establishment

    1997-11-01

    The research subjects in diffraction and scattering of materials with high brilliance synchrotron radiation such as SPring-8 (Super Photon ring 8 GeV) are summarized. The SPring-8 project is going well and 10 public beamlines will be opened for all users in October, 1997. Three JAERI beamlines are also under construction for researches of heavy element science, physical and structural properties under extreme conditions such as high temperature and high pressure. (author)

  8. Synchrotron radiation of a relativistic magneton

    Energy Technology Data Exchange (ETDEWEB)

    Bordovitsyn, V.A.; Torres, R.

    1986-11-01

    The classical theory of synchrotron radiation of an electrically neutral relativistic particle with a large intrinsic magnetic moment is considered (g-factor much greater than unit). The spectral-angular composition and polarization of the radiation are studied. The magneton radiation self-polarization time is calculated. It is shown that identical results follow from the Ternov-Bagrov-Khapaev quantum theory constructed on the basis of the Dirac-Pauli equation for a neutron.

  9. Diffraction measurements at sources of synchrotron radiation

    Czech Academy of Sciences Publication Activity Database

    Hašek, Jindřich

    Vol. 2a. Praha : Czech and Slovak Crystallographic Association, 2008, s. 15-16. ISSN 1211-5894. [Struktura 2008 - Colloquium of the Czech and Slovak Crystallographic Association. Valtice (CZ), 16.06.2008-20.06.2008] R&D Projects: GA AV ČR IAA500500701; GA ČR GA305/07/1073 Institutional research plan: CEZ:AV0Z40500505 Keywords : synchrotron radiation Subject RIV: CE - Biochemistry

  10. The Synchrotron Radiation for Steel Research

    OpenAIRE

    Piyada Suwanpinij

    2016-01-01

    The synchrotron X-ray radiation is a great tool in materials characterization with several advantageous features. The high intensity allows clear interaction signals and high energy of X-ray yields higher sampling volume. The samples do not need extra preparation and the microstructure is therefore not affected. With the tunability of the X-ray energy, a large range of elements and features in the samples can be investigated by different techniques, which is a significant difference between a...

  11. The Australian synchrotron - a progress report

    International Nuclear Information System (INIS)

    This paper summarises progress with the development of the Australian Synchrotron. The facility is based on the Boomerang Storage Ring which has a DBA structure with 14 superperiods. The design objective was to achieve a low emittance in a relatively compact circumference that had an excellent dynamic aperture and was obust with respect to potential construction aberrations. The potential suite of beamline and instrument stations is discussed and some examples are given

  12. Plasma diagnostics using synchrotron radiation in tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    Fidone, I.; Giruzzi, G.; Granata, G.

    1995-09-01

    This report deal with the use of synchrotron radiation in tokamaks. The main advantage of this new method is that it enables to overcome several deficiencies, caused by cut-off, refraction, and harmonic overlap. It also makes it possible to enhance the informative contents of the familiar low harmonic scheme. The basic theory of the method is presented and illustrated by numerical applications, for plasma parameters of relevance in present and next step tokamaks. (TEC). 10 refs., 13 figs.

  13. Synchrotron radiation studies of inorganic-organic semiconductor interfaces

    CERN Document Server

    Evans, D A; Vearey-Roberts, A R; Bushell, A; Cabailh, G; O'Brien, S; Wells, J W; McGovern, I T; Dhanak, V R; Kampen, T U; Zahn, D R T; Batchelor, D

    2003-01-01

    Organic semiconductors (polymers and small molecules) are widely used in electronic and optoelectronic technologies. Many devices are based on multilayer structures where interfaces play a central role in device performance and where inorganic semiconductor models are inadequate. Synchrotron radiation techniques such as photoelectron spectroscopy (PES), near-edge X-ray absorption fine structure (NEXAFS) and X-ray standing wave spectroscopy (XSW) provide a powerful means of probing the structural, electronic and chemical properties of these interfaces. The surface-specificity of these techniques allows key properties to be monitored as the heterostructure is fabricated. This methodology has been directed at the growth of hybrid organic-inorganic semiconductor interfaces involving copper phthalocyanine as the model organic material and InSb and GaAs as the model inorganic semiconductor substrates. Core level PES has revealed that these interfaces are abrupt and chemically inert due to the weak bonding between t...

  14. Deutsches Elektronen-Synchrotron DESY. Scientific annual report 1995

    International Nuclear Information System (INIS)

    As a result of the symbiosis between particle physics and synchrotron radiation research, the spectrum of research done at DESY is extraordinarily large, from research on elementary particles to solid state and surface physics, geosciences, chemistry and materials research up to molecular biology and medical diagnostics. This programme is unique in Europe. In 1995, research work was done by nearly 3000 scientists from 280 different institutions in 35 countries. About 1200 of these scientists were experts in particle physics. DESY is also one of the most important national research centers of Germany: The experimental facilities of HERA and DORIS III are used by about 1700 scientists from more than 90 German universities and research institutions. The annual report deals with research, machines and operation. (orig./DG)

  15. Applications of synchrotron x-ray diffraction topography to fractography

    International Nuclear Information System (INIS)

    Fractographs have been taken using a variety of probes each of which produces different types of information. Methods which have been used to examine fracture surfaces include: (a) optical microscopy, particularly interference contrast methods, (b) scanning electron microscopy (SEM), (c) SEM with electron channelling, (d) SEM with selected-area electron channelling, (e) Berg-Barrett (B-B) topography, and now (f) synchrotron x-radiation fractography (SXRF). This review concentrated on the role that x-ray methods can play in such studies. In particular, the ability to nondestructively assess the subsurface microstructure associated with the fracture to depths of the order of 5 to 10 μm becomes an important attribute for observations of a large class of semi-brittle metals, semiconductors and ceramics

  16. Paraxial Green's functions in synchrotron radiation theory

    International Nuclear Information System (INIS)

    This work contains a systematic treatment of single particle synchrotron radiation and some application to realistic beams with given cross section area, divergence and energy spread. Standard theory relies on several approximations whose applicability limits and accuracy are often forgotten. We begin remarking that on the one hand, a paraxial approximation can always be applied without loss of generality and with ultra relativistic accuracy. On the other hand, dominance of the acceleration field over the velocity part in the Lienard-Wiechert expressions is not always guaranteed and constitutes a separate assumption, whose applicability is discussed. Treating synchrotron radiation in paraxial approximation we derive the equation for the slow varying envelope function of the Fourier components of the electric field vector. Calculations of Synchrotron Radiation properties performed by others showed that the phase of the Fourier components of the electric field vector differs from the phase of a virtual point source. In this paper we present a systematic, analytical description of this phase shift, calculating amplitude and phase of electric field from bending magnets, short magnets, two bending magnet system separated by a straight section (edge radiation) and undulator devices. We pay particular attention to region of applicability and accuracy of approximations used. Finally, taking advantage of results of analytical calculation presented in reduced form we analyze various features of radiation from a complex insertion device (set of two undulators with a focusing triplet in between) accounting for the influence of energy spread and electron beam emittance. (orig.)

  17. Improvements in the Rapid Cycling Synchrotron

    International Nuclear Information System (INIS)

    The Rapid Cycling Synchrotron1 (RCS), originally designed as an injection energy booster for the Zero Gradient Synchrotron (ZGS), operated under contraints imposed by ZGS operation until December 1979. Once these restraints were removed, the RCS made rapid strides toward its nearterm goals of 8 μA of protons for Argonne National Laboratory's (ANL) Intense Pulsed Neutron Source (IPNS) program. Reliable 30 Hz operation was achieved in the spring of 1980 with beams as high as 2 x 1012 protons per pulse and weekly average intensities of over 6 μA on target. These gains resulted from better injection matching, more efficient RF turn-on and dynamic chromatricity control. A high intensity small diameter synchrotron, such as the RCS, has special problems with loss control which dictate prudence during intensity improvment activities. Additional improvements were made to the machine starting in August of 1980 while the extraction magnets were relocated for operation with the IPNS-I target. These improvements have now been completed. Startup of the accelerator is now underway, and it is clear that these modifications have resulted in a radio-actively cleaner operation. It is too early to evaluate the effects of the improvements on intensity and reliability, but a single pulse extracted intensity of 2.4 x 1012 protons has been achieved, a 20% increase. The studies and equipment leading to the intensity gains are discussed. (orig.)

  18. Synchrotron-radiation experiments with recoil ions

    Energy Technology Data Exchange (ETDEWEB)

    Levin, J.C.

    1989-01-01

    Studies of atoms, ions and molecules with synchrotron radiation have generally focused on measurements of properties of the electrons ejected during, or after, the photoionization process. Much can also be learned, however, about the atomic or molecular relaxation process by studies of the residual ions or molecular fragments following inner-shell photoionization. Measurements are reported of mean kinetic energies of highly charged argon, krypton, and xenon recoil ions produced by vacancy cascades following inner-shell photoionization using white and monochromatic synchrotron x radiation. Energies are much lower than for the same charge-state ions produced by charged-particle impact. The results may be applicable to design of future angle-resolved ion-atom collision experiments. Photoion charge distributions are presented and compared with other measurements and calculations. Related experiments with synchrotron-radiation produced recoil ion, including photoionization of stored ions and measurement of shakeoff in near-threshold excitation, are briefly discussed. 24 refs., 6 figs., 1 tab.

  19. MICROANALYSIS OF MATERIALS USING SYNCHROTRON RADIATION.

    Energy Technology Data Exchange (ETDEWEB)

    JONES,K.W.; FENG,H.

    2000-12-01

    High intensity synchrotron radiation produces photons with wavelengths that extend from the infrared to hard x rays with energies of hundreds of keV with uniquely high photon intensities that can be used to determine the composition and properties of materials using a variety of techniques. Most of these techniques represent extensions of earlier work performed with ordinary tube-type x-ray sources. The properties of the synchrotron source such as the continuous range of energy, high degree of photon polarization, pulsed beams, and photon flux many orders of magnitude higher than from x-ray tubes have made possible major advances in the possible chemical applications. We describe here ways that materials analyses can be made using the high intensity beams for measurements with small beam sizes and/or high detection sensitivity. The relevant characteristics of synchrotron x-ray sources are briefly summarized to give an idea of the x-ray parameters to be exploited. The experimental techniques considered include x-ray fluorescence, absorption, and diffraction. Examples of typical experimental apparatus used in these experiments are considered together with descriptions of actual applications.

  20. 50 Years of synchrotrons Adams' Memorial lecture

    CERN Document Server

    Lawson, J D; CERN. Geneva

    1996-01-01

    Fifty years ago Frank Goward of the Atomic Energy Research Establishment Group at Malvern converted a small American betatron to make the worldÕs first synchrotron. At the same time Marcus Oliphant was planning to build at Birmingham a large proton machine with a ring magnet and variable magnetic field. Ideas for this had come to him during night-shifts tending the electromagnetic separators at Oak Ridge during the war. Some seven years later, in 1953, a group gathered together in Geneva to build the PS. A major contributor to the design work which had made this possible was John Adams. An account of some of the achievements in these eventful years will be presented. CERN has built nine synchrotrons/colliders and two temporary test rings. Eight machines are still running. The review will start with the PS, the first proton synchrotron based on the alternating gradient principle invented in 1952 at BNL. The design work of the PS team, under the enlightened leadership of J.B. Adams, and the construction of the...

  1. Tabletop synchrotron and its unique features

    CERN Document Server

    Yamada, H

    2002-01-01

    Two synchrotrons, AURORA and MIRRORCLE, were built in Ritsumeikan University. MIRRORCLE-20 is the smallest normal conduction synchrotron (15 cm orbit radius and 1.2 m outer diameter) in the world. It uses 2/3 resonance method for electron beam incidence but is not optimized for X-ray generation. MIRRORCLE-6 shall be optimized for X-ray generation. X-ray generated by MIRRORCLE shows very flat white light, rich in hard X-ray, pulse with width changeable from a few mu s to a few ms , wide radiation angle of 25 mrad at MIRRORCLE-20 and 80 mrad at MIRRORCLE-8 and high coherence. The feature such as pulsed light and high coherence is expected to new application which photon radiation cannot practice. Imaging experiments by MIRRORCLE were carried out by Cu plate, Al plate, Teflon and acryl plate. We took a photograph of insect, electric lamp, connector, and cyclotron. New X-ray generation mechanism, X-ray strength, development of tabletop synchrotron and features of X-ray beam are explained. (S.Y.)

  2. A novel approach to synchrotron radiation simulation

    CERN Document Server

    Trad, G; Goldblatt, A; Mazzoni, S; Roncarolo, F

    2014-01-01

    At the Large Hadron Collider (LHC) at CERN, synchrotron radiation (SR) is used to continuously monitor the transverse properties of the beams. Unfortunately the machine and beam parameters are such that the useful radiation emitted inside a separation dipole, chosen as source, is diffraction limited heavily affecting the accuracy of the measurement. In order to deconvolve the diffraction effects from the acquired beam images and in order to design an alternative monitor based on a double slit interferometer an extensive study of the synchrotron light source and of the optical propagation has been made. This study is based on simulations combining together several existing tools: SRW for the source, ZEMAX for the transport and MATLAB for the “glue” and analysis of the results. The resulting tool is very powerful and can be easily adapted to other synchrotron radiation problems. In this paper the simulation package and the way it is used will be described as well as the results obtained for the LHC and SPS.

  3. Many-body dispersion effects in the binding of adsorbates on metal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Maurer, Reinhard J. [Department of Chemistry, Yale University, New Haven, Connecticut 06520 (United States); Ruiz, Victor G.; Tkatchenko, Alexandre [Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin (Germany)

    2015-09-14

    A correct description of electronic exchange and correlation effects for molecules in contact with extended (metal) surfaces is a challenging task for first-principles modeling. In this work, we demonstrate the importance of collective van der Waals dispersion effects beyond the pairwise approximation for organic–inorganic systems on the example of atoms, molecules, and nanostructures adsorbed on metals. We use the recently developed many-body dispersion (MBD) approach in the context of density-functional theory [Tkatchenko et al., Phys. Rev. Lett. 108, 236402 (2012) and Ambrosetti et al., J. Chem. Phys. 140, 18A508 (2014)] and assess its ability to correctly describe the binding of adsorbates on metal surfaces. We briefly review the MBD method and highlight its similarities to quantum-chemical approaches to electron correlation in a quasiparticle picture. In particular, we study the binding properties of xenon, 3,4,9,10-perylene-tetracarboxylic acid, and a graphene sheet adsorbed on the Ag(111) surface. Accounting for MBD effects, we are able to describe changes in the anisotropic polarizability tensor, improve the description of adsorbate vibrations, and correctly capture the adsorbate–surface interaction screening. Comparison to other methods and experiment reveals that inclusion of MBD effects improves adsorption energies and geometries, by reducing the overbinding typically found in pairwise additive dispersion-correction approaches.

  4. Many-body dispersion effects in the binding of adsorbates on metal surfaces

    Science.gov (United States)

    Maurer, Reinhard J.; Ruiz, Victor G.; Tkatchenko, Alexandre

    2015-09-01

    A correct description of electronic exchange and correlation effects for molecules in contact with extended (metal) surfaces is a challenging task for first-principles modeling. In this work, we demonstrate the importance of collective van der Waals dispersion effects beyond the pairwise approximation for organic-inorganic systems on the example of atoms, molecules, and nanostructures adsorbed on metals. We use the recently developed many-body dispersion (MBD) approach in the context of density-functional theory [Tkatchenko et al., Phys. Rev. Lett. 108, 236402 (2012) and Ambrosetti et al., J. Chem. Phys. 140, 18A508 (2014)] and assess its ability to correctly describe the binding of adsorbates on metal surfaces. We briefly review the MBD method and highlight its similarities to quantum-chemical approaches to electron correlation in a quasiparticle picture. In particular, we study the binding properties of xenon, 3,4,9,10-perylene-tetracarboxylic acid, and a graphene sheet adsorbed on the Ag(111) surface. Accounting for MBD effects, we are able to describe changes in the anisotropic polarizability tensor, improve the description of adsorbate vibrations, and correctly capture the adsorbate-surface interaction screening. Comparison to other methods and experiment reveals that inclusion of MBD effects improves adsorption energies and geometries, by reducing the overbinding typically found in pairwise additive dispersion-correction approaches.

  5. Many-body dispersion effects in the binding of adsorbates on metal surfaces.

    Science.gov (United States)

    Maurer, Reinhard J; Ruiz, Victor G; Tkatchenko, Alexandre

    2015-09-14

    A correct description of electronic exchange and correlation effects for molecules in contact with extended (metal) surfaces is a challenging task for first-principles modeling. In this work, we demonstrate the importance of collective van der Waals dispersion effects beyond the pairwise approximation for organic-inorganic systems on the example of atoms, molecules, and nanostructures adsorbed on metals. We use the recently developed many-body dispersion (MBD) approach in the context of density-functional theory [Tkatchenko et al., Phys. Rev. Lett. 108, 236402 (2012) and Ambrosetti et al., J. Chem. Phys. 140, 18A508 (2014)] and assess its ability to correctly describe the binding of adsorbates on metal surfaces. We briefly review the MBD method and highlight its similarities to quantum-chemical approaches to electron correlation in a quasiparticle picture. In particular, we study the binding properties of xenon, 3,4,9,10-perylene-tetracarboxylic acid, and a graphene sheet adsorbed on the Ag(111) surface. Accounting for MBD effects, we are able to describe changes in the anisotropic polarizability tensor, improve the description of adsorbate vibrations, and correctly capture the adsorbate-surface interaction screening. Comparison to other methods and experiment reveals that inclusion of MBD effects improves adsorption energies and geometries, by reducing the overbinding typically found in pairwise additive dispersion-correction approaches. PMID:26374001

  6. Emerging Approaches in Synchrotron Studies of Materials from Cultural and Natural History Collections.

    Science.gov (United States)

    Bertrand, Loïc; Bernard, Sylvain; Marone, Federica; Thoury, Mathieu; Reiche, Ina; Gourrier, Aurélien; Sciau, Philippe; Bergmann, Uwe

    2016-02-01

    Synchrotrons have provided significant methods and instruments to study ancient materials from cultural and natural heritages. New ways to visualise (surfacic or volumic) morphologies are developed on the basis of elemental, density and refraction contrasts. They now apply to a wide range of materials, from historic artefacts to paleontological specimens. The tunability of synchrotron beams owing to the high flux and high spectral resolution of photon sources is at the origin of the main chemical speciation capabilities of synchrotron-based techniques. Although, until recently, photon-based speciation was mainly applicable to inorganic materials, novel developments based, for instance, on STXM and deep UV photoluminescence bring new opportunities to study speciation in organic and hybrid materials, such as soaps and organometallics, at a submicrometric spatial resolution over large fields of view. Structural methods are also continuously improved and increasingly applied to hierarchically structured materials for which organisation results either from biological or manufacturing processes. High-definition (spectral) imaging appears as the main driving force of the current trend for new synchrotron techniques for research on cultural and natural heritage materials. PMID:27572990

  7. New synchrotron radiation facility project. Panel on new synchrotron radiation facility project

    CERN Document Server

    Sato, S; Kimura, Y

    2003-01-01

    The project for constructing a new synchrotron radiation facility dedicated to the science in VUV (or EUV) and Soft X-ray (SX) region has been discussed for these two years at the Panel on New Synchrotron Radiation Facility Project. The Panel together with the Accelerator Design Working Group (WG), Beamline Design WG and Research Program WG suggested to the Ministry of Education, Science, Culture and Sports the construction of a 1.8 GeV electron storage ring suitable for 'Top-Up' operation and beamlines and monochromators designed for undulator radiation. The scientific programs proposed by nationwide scientists are summarized with their requirements of the characteristics of the beam. (author)

  8. Medical applications of synchrotron radiation at the National Synchrotron Light Source

    International Nuclear Information System (INIS)

    The overriding features of the synchrotron beams which make them applicable to medical research are their extremely high intensity and broadband energy spectrum. Several orders of magnitude separate the smooth, continuous spectrum of the synchrotron from the sharply peaked characteristic emission spectrum of a conventional source. Basically, the high intensity and tunability allow monochromatic beams to be generated at virtually any energy. The standard problem of beam hardening in both medical imaging and therapy is eliminated by the monochromatic beams since the energy spectrum does not change with passage through tissue. The tunable spectrum allows enhancement of images and therapeutic dose by selection of the most effective energy for a given procedure

  9. The 10 to 20 GeV Cornell Electron Synchrotron

    CERN Document Server

    Wilson, Richard R

    1967-01-01

    The National Science Foundation awarded a contract to Cornell University on April 4, 1965 for the construction of a 10 Gev electron synchrotron. The synchrotron itself has now been built and preliminary tests have been made at low energy. The present report is largely a revision and up-dating of CS DC-26 which was written two years ago when the construction of the synchrotron was authorized.

  10. Atomic photoelectron-spectroscopy studies using synchrotron radiation

    International Nuclear Information System (INIS)

    Photoelectron spectroscopy combined with tunable synchrotron radiation has been used to study the photoionization process in several atomic systems. The time structure of the synchrotron radiation source at the Stanford Synchrotron Radiation Laboratory (SSRL) was used to record time-of-flight (TOF) photoelectron spectra of gaseous Cd, Hg, Ne, Ar, Ba, and Mn. The use of two TOF analyzers made possible the measurement of photoelectron angular distributions as well as branching ratios and partial cross sections

  11. Atomic photoelectron-spectroscopy studies using synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Kobrin, P.H.

    1983-02-01

    Photoelectron spectroscopy combined with tunable synchrotron radiation has been used to study the photoionization process in several atomic systems. The time structure of the synchrotron radiation source at the Stanford Synchrotron Radiation Laboratory (SSRL) was used to record time-of-flight (TOF) photoelectron spectra of gaseous Cd, Hg, Ne, Ar, Ba, and Mn. The use of two TOF analyzers made possible the measurement of photoelectron angular distributions as well as branching ratios and partial cross sections.

  12. Injection System design for a hadron therapy Synchrotron

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jin-Quan; SONG Ming-Tao; WEI Bao-Wen

    2008-01-01

    A synchrotron is designed for tumour therapy with C6+ ions or proton.Its injector is a cyclotron, which delivers C5+or H+2 ions to the synchrotron.After comparing the methods of the single-turn injection, the multi-turn injection and the stripping injection,this paper chooses the stripping injection method.In addition,the concept design of the injection system is presented,in which the synchrotron lattice is optimized.

  13. The Synchrotron Boiler: a Thermalizer in Seyfert Galaxies

    OpenAIRE

    Ghisellini, Gabriele; Haardt, Francesco; Svensson, Roland

    1996-01-01

    There are difficulties in understanding what keeps the plasma thermalized in compact sources, especially during rapid variations of the emitted flux. Particle-particle collisions are too inefficient in hot rarefied plasmas, and a faster process is called for. Synchrotron absorption is such a process. We show that relativistic electrons can thermalize in a few synchrotron cooling times by emitting and absorbing cyclo-synchrotron photons. The resulting equilibrium distribution is a Maxwellian a...

  14. A novel method of supporting gold nanoparticles on MWCNTs: Synchrotron X-ray reduction

    Institute of Scientific and Technical Information of China (English)

    Kuan-Nan Lin; Tsung-Yeh Yang; Hong-Ming Lin; Yeu-Kuang Hwu; She-Huang Wu; Chung-Kwei Lin

    2007-01-01

    Gold nanoparticles decorating the surface of multiwalled carbon nanotubes (MWCNTs) are prepared by photochemical reduction. The gold clusters form different interesting geometrical faceted shapes in accordance to time duration of synchrotron X-ray irradiation. The shape of nanogold could be spherical, rod-like, or triangular. Carbon nanotubes serve as optimal templates for the heterogeneous nucleation of gold nanocrystals. These nanocrystal structures are characterized by transmission electron microscope (TEM) and element analysis by energy dispersive spectroscopy (EDS).

  15. Synchrotron Vacuum Ultraviolet Light and Soft X-Ray Radiation Effects on Aluminized Teflon FEP Investigated

    Science.gov (United States)

    Dever, Joyce A.; Townsend, Jacqueline A.; Gaier, James R.; Jalics, Alice I.

    1999-01-01

    Since the Hubble Space Telescope (HST) was deployed in low Earth orbit in April 1990, two servicing missions have been conducted to upgrade its scientific capabilities. Minor cracking of second-surface metalized Teflon FEP (DuPont; fluorinated ethylene propylene) surfaces from multilayer insulation (MLI) was first observed upon close examination of samples with high solar exposure retrieved during the first servicing mission, which was conducted 3.6 years after deployment. During the second HST servicing mission, 6.8 years after deployment, astronaut observations and photographic documentation revealed significant cracks in the Teflon FEP layer of the MLI on both the solar- and anti-solar-facing surfaces of the telescope. NASA Goddard Space Flight Center directed the efforts of the Hubble Space Telescope MLI Failure Review Board, whose goals included identifying the low-Earth-orbit environmental constituent(s) responsible for the cracking and embrittling of Teflon FEP which was observed during the second servicing mission. The NASA Lewis Research Center provided significant support to this effort. Because soft x-ray radiation from solar flares had been considered as a possible cause for the degradation of the mechanical properties of Teflon FEP (ref. 1), the effects of soft xray radiation and vacuum ultraviolet light on Teflon FEP were investigated. In this Lewisled effort, samples of Teflon FEP with a 100-nm layer of vapor-deposited aluminum (VDA) on the backside were exposed to synchrotron radiation of various vacuum ultraviolet and soft x-ray wavelengths between 18 nm (69 eV) and 0.65 nm (1900 eV). Synchrotron radiation exposures were conducted using the National Synchrotron Light Source at Brookhaven National Laboratory. Samples of FEP/VDA were exposed with the FEP surface facing the synchrotron beam. Doses and fluences were compared with those estimated for the 20-yr Hubble Space Telescope mission.

  16. Impact of synchrotron radiation on macromolecular crystallography: a personal view

    International Nuclear Information System (INIS)

    This article, largely based on personal experiences of the authors, reviews the early history of the application of synchrotron radiation to structural biology, and particularly protein crystallography, to show the tremendous impact that this experimental innovation has had on these disciplines. The introduction of synchrotron radiation sources almost four decades ago has led to a revolutionary change in the way that diffraction data from macromolecular crystals are being collected. Here a brief history of the development of methodologies that took advantage of the availability of synchrotron sources are presented, and some personal experiences with the utilization of synchrotrons in the early days are recalled

  17. Synchrotron radiation direct photoetching of polymers and crystals for micromachining

    International Nuclear Information System (INIS)

    Synchrotron radiation etching of polymers and optical crystals which are transparent throughout the spectral range from visible to ultraviolet has been carried out without using any chemicals, successfully creating high-aspect-ratio microstructures for micromachining. A detailed study of the etching rates by varying the synchrotron beam current, sample temperature, beam size and aspect ratio showed that this synchrotron radiation process is essentially different from laser ablation, while an in situ mass spectrometric analysis of gaseous etching products showed that the dissociation mechanism involved with the synchrotron radiation processing, even with heating, is completely different from the thermal dissociation of the laser ablation

  18. Growth of coronene on (100)- and (111)-surfaces of fcc-crystals

    Science.gov (United States)

    Huempfner, Tobias; Sojka, Falko; Forker, Roman; Fritz, Torsten

    2015-09-01

    The growth of coronene thin films is studied via low-energy electron diffraction (LEED) and scanning tunneling microscopy (STM) comparing metal substrates with different lattice constants, different surface symmetry, and also with surface passivation, namely Cu(111), Ag(111), Ag(100), and (100)-terminated KCl/Ag(100). In particular, we investigate the evolution of the coronene lattice parameters upon coverage- and temperature-variation. On the pristine metal surfaces we observe disordered phases at low coverage. Further deposition leads to hexagonal arrangement of the molecules. With increasing coverage the lattice constant decreases continuously, whereas on Cu(111) the molecular unit cell additionally rotates w.r.t. the substrate lattice. We also discuss the interaction mechanisms that are responsible for this behavior. Due to the continuous change in the lattice dimensions we observe many incommensurate structures that were stable during our measurements, however the close-packed structures we found were always commensurate. The use of a passivation layer leads to the formation of a bulk-like structure consisting of molecules adsorbed in an upright standing manner which is stable at low temperatures only.

  19. Application of synchrotron radiation in material Science

    International Nuclear Information System (INIS)

    In recent years many synchrotron radiation facilities are built around the world. The properties of this radiation, it's intensity and tuneability, are leading to exciting new experiments in chemistry, physics, biology and material sciences. In X-ray crystallographic studies, data can be collected on very small samples of only a few microns in size and time as short as one millisecond. Other techniques allow us to probe the local structures of impurities in technologically important materials. In the present paper unique properties of synchrotron radiation will be described. X-ray diffraction (XRD) and X-ray Absorption Fine Structure (XAFS) spectroscopic techniques are now routinely used for materials characterization. X-ray Absorption Fine Structure (XAFS) spectroscopic techniques have been applied to study the local structural environment of host and dopant cations in complex systems. X-ray Absorption Near Edge Structure (XANES) spectroscopy is useful to determine the valence state of different cations. To examine the local structure around different cations Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy is the most appropriate technique. A review of these methodologies and the results on Yba/sub 2/ Cu/sub 3-x/ Sb/sub x/O/sub 7/, and SrFe/sub 1-x/ Nb/sub x/O/sub 3/ (where x = 0.0 and 0.5) will be presented. The Synchrotron light for Experimental Science and Applications in the Middle East (SESAME) is under construction in jordan, Pakistan in one of the member states of SESAME project, therefore a brief review of SESAME will be presented. (author)

  20. Laser synchrotron radiation and beam cooling

    Energy Technology Data Exchange (ETDEWEB)

    Esarey, E.; Sprangle, P.; Ting, A. [Naval Research Lab., Washington, DC (United States)] [and others

    1995-12-31

    The interaction of intense {approx_gt} 10{sup 18} W/cm{sup 2}, short pulse ({approx_lt} 1 ps) lasers with electron beams and plasmas can lead to the generation of harmonic radiation by several mechanisms. Laser synchrotron radiation may provide a practical method for generating tunable, near monochromatic, well collimated, short pulse x-rays in compact, relatively inexpensive source. The mechanism for the generation of laser synchrotron radiation is nonlinear Thomson scattering. Short wavelengths can be generated via Thomson scattering by two methods, (i) backscattering from relativistic electron beams, in which the radiation frequency is upshifted by the relativistic factor 4{gamma}{sup 2}, and (ii) harmonic scattering, in which a multitude of harmonics are generated with harmonic numbers extending out to the critical harmonic number nc{approx_equal}a{sub 0}{sup 3} {much_gt} 1, where a{sub 0} {approx_equal}10{sup -9}{lambda}I{sup 1/2}, {lambda} is the laser wavelength in {mu}m and I is the laser intensity in W/cm{sup 2}. Laser synchrotron sources are capable of generating short ({approx_lt} ps) x-ray pulses with high peak flux ({approx_gt} 10{sup 21} photons/s) and brightness ({approx_gt}{sup 19} photons/s-mm{sup 2}-mrad{sup 2} 0.1%BW. As the electron beam radiates via Thomson scattering, it can subsequently be cooled, i.e., the beam emittance and energy spread can be reduced. This cooling can occur on rapid ({approximately} ps) time scales. In addition, electron distributions with sufficiently small axial energy spreads can be used to generate coherent XUV radiation via a laser-pumped FEL mechanism.

  1. Understanding Periodic Dislocations in 2D Supramolecular Crystals: The PFP/Ag(111) Interface

    DEFF Research Database (Denmark)

    Goiri, E.; García Lastra, Juan Maria; Corso, M.;

    2012-01-01

    interplay with molecule–substrate interactions is very subtle, making it difficult to single out the driving force for a nanoscale dislocation pattern. On the basis of a combined experimental and theoretical work, we here show that periodic dislocations in a molecular PFP film are mainly driven by the...... optimization of molecule–substrate interactions. Compared to inorganic networks however, it implies a much lower energy imbalance, allowing a thermally induced transition from a low-energy strain dislocation pattern to a high-energy incommensurate moiré....

  2. STM-imaging of nanostructure dynamics on Ag(111)-experimental challenges and solutions

    OpenAIRE

    Morgenstern, Karina; Rosenfeld, Georg; Poelsema, Bene; Comsa, George

    1996-01-01

    We describe experimental problems arising with the continuous observation of nanostructure dynamics by STM. We discuss the necessity to use a high-speed STM, possibilities to deal with the thermal drift, and tests to rule out the influence of the scanning process on the observation.

  3. Synchrotron radiation facilities in the USA

    International Nuclear Information System (INIS)

    With the successful commissioning and achievement of significant milestones at both the 7-GeV Advanced Photon Source (APS) and the 1.5- GeV Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory, synchrotron radiation research capability in the United States holds the promise of many important discoveries in the decade to come. An overview of current accelerator commissioning performance at the American third-generation light sources, state-of-the-art developments at first- and second-generation sources, and a preview of fourth-generation source progress is presented

  4. X-ray microscopy using synchrotron radiation

    International Nuclear Information System (INIS)

    The system for x-ray microscopy now being developed at the X-26 beam line of the Brookhaven National Synchrotron Light Source (NSLS) is described here. Examples of the use of x-ray microscopy for trace element geochemistry, biology and medicine, and materials investigations are given to emphasize the scientific applications of the technique. Future directions for the improvement and further development of the X-26 microscope and of the x-ray microscopy field in general are discussed. 11 refs., 7 figs

  5. Emittance growth from transient coherent synchrotron radiation

    International Nuclear Information System (INIS)

    If the energies of individual particles in a bunch change as the bunch traverses a bending system, even if it is achromatic, betatron oscillations can be excited. Consequently, the transverse emittance of the bunch will grow as it moves downstream. Short bunches may be particularly susceptible to emission of coherent synchrotron radiation which can act back on the particles to change their energies and trajectories. Because a bend spans a well-defined length and angle, the bunch-excited wakefield and its effect back on the bunch are inherently transient. We outline a recently developed theory of this effect and apply it to example bending systems

  6. Matching to gantries for medical synchrotrons

    CERN Document Server

    Benedikt, Michael

    1997-01-01

    Treatment of tumours by hadron-therapy is greatly improved if the patient can be irradiated from different directions. This task is performed by a gantry, i.e. a section of beam line that can be rotated around the patient. The gantry optics have to be designed in such a way that the beam at the patient is independent of the rotation angle. The various matching techniques are briefly reviewed in the light of the current development in medical synchrotrons towards active scanning, which requires a small, high-precision beam spot at the patient. In particular, beam delivery systems with rotators are discussed.

  7. CRYRING - a synchrotron, cooler and storage ring

    Energy Technology Data Exchange (ETDEWEB)

    Abrahamsson, K.; Andler, G.; Bagge, L.; Beebe, E.; Carle, P.; Danared, H.; Egnell, S.; Ehrnsten, K.; Engstroem, M.; Herrlander, C.J.; Hilke, J.; Jeansson, J.; Kaellberg, A.; Leontein, S.; Liljeby, L.; Nilsson, A.; Paal, A.; Rensfelt, K.G.; Rosengaard, U.; Simonsson, A.; Soltan, A.; Starker, J.; Ugglas, M. (Manne Siegbahn Inst. of Physics, Stockholm (Sweden)) Filevich, A. (CNEA, Physics Dept., Tandar, Buenos Aires (Argentina))

    1993-06-01

    CRYRING is a small synchrotron and storage ring equipped with electron cooling. Highly charged ions from the electron beam ion source CRYSIS or singly charged ions from the plasmatron source MINIS are injected via an RFQ into the ring. The facility is in the commissioning phase. Full design energy has been achieved and electron cooling demonstrated both for atomic and molecular ions. The experimental program started in August with two projects, dissociative recombination of H[sup +][sub 3] ions and radiative recombination to deuterons. The status as of September 20, 1992, is reported. (orig.)

  8. Bent approximations to synchrotron radiation optics

    International Nuclear Information System (INIS)

    Ideal optical elements can be approximated by bending flats or cylinders. This paper considers the applications of these approximate optics to synchrotron radiation. Analytic and raytracing studies are used to compare their optical performance with the corresponding ideal elements. It is found that for many applications the performance is adequate, with the additional advantages of lower cost and greater flexibility. Particular emphasis is placed on obtaining the practical limitations on the use of the approximate elements in typical beamline configurations. Also considered are the possibilities for approximating very long length mirrors using segmented mirrors

  9. Biological effects of synchrotron radiation on crops

    Institute of Scientific and Technical Information of China (English)

    唐掌雄; 董保中; 等

    1996-01-01

    The sensitivity of germinating seeds of barley,winter wheat and spring one to synchrotron ultraviolet radiation is barley>winter wheat and spring one.But when dry seeds of the three crops are irradiated by 3.5-22keV X-rays,the sequence of their sensitivity to radiation can be changed.for irradiation of 0.6-3keV ultra soft X-rays,0.40-0.90 of the seedlings of the first generation appear mutation of striped chlorophyll defect.This biological effect has never been found for irradiation of other rays.

  10. Tolerances in diffraction limited synchrotron light sources

    International Nuclear Information System (INIS)

    The PEP storage ring at Stanford can be operated to become a synchrotron light source of super-high brightness. Using a combination of a high-tune configuration and damping wigglers, the beam emittance can be reduced to less than 6 A rad at 6 GeV. For such small beam emittance, alignment and field tolerances as well as nonlinear fields in the wiggler magnets can significantly perturb the attainable low-emittance. This paper reports on studies to control and establish the tolerances required for the operation of a super-low-emittance storage ring. (orig.)

  11. Precision geometric parameter gage for synchrotron radiation

    CERN Document Server

    Gubrienko, K I; Makonin, S; Seleznev, V; Solodovnik, F; Sytin, A N; Vrazhnov, M; Wittenburg, K

    2001-01-01

    This article includes the description of the geometric parameter gage device prototype for synchrotron radiation of HERA collider (DESY). The system construction which capable to measure photo current, caused by such a radiation in a refractory metal, described here. The system component parts are: measuring heads and photo current measuring electronics designed by IHEP, stepper motor by Vacuum Generators with HEDS-550X encoder by Hewlett Packard, PCI-STEP-4CX 4-Axis Closed Loop Step controller by National Instruments. The device is controlled by means of Microsoft Visual Basic program using Value Motion Windows Libraries. The device prototype was tested in the beam of the DORIS storage ring.

  12. Synchrotron radiation facilities in the USA

    Energy Technology Data Exchange (ETDEWEB)

    Decker, G.

    1996-07-01

    With the successful commissioning and achievement of significant milestones at both the 7-GeV Advanced Photon Source (APS) and the 1.5- GeV Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory, synchrotron radiation research capability in the United States holds the promise of many important discoveries in the decade to come. An overview of current accelerator commissioning performance at the American third-generation light sources, state-of-the-art developments at first- and second-generation sources, and a preview of fourth-generation source progress is presented.

  13. 3D IMAGING USING COHERENT SYNCHROTRON RADIATION

    Directory of Open Access Journals (Sweden)

    Peter Cloetens

    2011-05-01

    Full Text Available Three dimensional imaging is becoming a standard tool for medical, scientific and industrial applications. The use of modem synchrotron radiation sources for monochromatic beam micro-tomography provides several new features. Along with enhanced signal-to-noise ratio and improved spatial resolution, these include the possibility of quantitative measurements, the easy incorporation of special sample environment devices for in-situ experiments, and a simple implementation of phase imaging. These 3D approaches overcome some of the limitations of 2D measurements. They require new tools for image analysis.

  14. Medical applications of synchrotron radiation. Ch. 10

    International Nuclear Information System (INIS)

    Synchrotron radiation has a number of properties which make it uniquely suited for medical diagnostic imaging. The radiation is intense and can be readily monochromatized. With these highly intense, mono-chromatized X-ray beams, iodine K-edge di-chromatography can yield images which greatly enhance the visualization of iodine containing structures. As this technology continues to improve, the possibility of performing diagnostic cardiac, neuroradiological, and other vascular examinations with minimally invasive peripheral venous injections of iodinated contrast agent becomes increasingly practical. (author). 10 refs.; 6 figs

  15. Effective spectrum width of the synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Bagrov, V. G., E-mail: bagrov@phys.tsu.ru [Department of Physics, Tomsk State University, Tomsk (Russian Federation); Institute of High Current Electronics, SB RAS, Tomsk (Russian Federation); Gitman, D. M., E-mail: gitman@if.usp.br [Department of Physics, Tomsk State University, Tomsk (Russian Federation); Institute of Physics, University of São Paulo, São Paulo (Brazil); P.N.Lebedev Physical Institute, Moscow (Russian Federation); Levin, A. D., E-mail: alevin@if.usp.br [Institute of Physics, University of São Paulo, São Paulo (Brazil); Loginov, A. S.; Saprykin, A. D. [Department of Physics, Tomsk State University, Tomsk (Russian Federation)

    2015-11-25

    For an exact quantitative description of spectral properties of synchrotron radiation (SR), the concept of effective width of the spectrum is introduced. In the most interesting case, which corresponds to the ultrarelativistic limit of SR, the effective width of the spectrum is calculated for the polarization components, and new physically important quantitative information on the structure of spectral distributions is obtained. For the first time, the spectral distribution for the circular polarization component of the SR for the upper half-space is obtained within classical theory.

  16. Synchrotron Lightcurves of blazars in a time-dependent synchrotron-self Compton cooling scenario

    CERN Document Server

    Zacharias, Michael

    2013-01-01

    Blazars emit non-thermal radiation in all frequency bands from radio to \\gamma-rays. Additionally, they often exhibit rapid flaring events at all frequencies with doubling time scale of the TeV and X-ray flux on the order of minutes, and such rapid flaring events are hard to explain theoretically. We explore the effect of the synchrotron-self Compton cooling, which is inherently time-dependent, leading to a rapid cooling of the electrons. Having discussed intensively the resulting effects of this cooling scenario on the spectral energy distribution of blazars in previous papers, the effects of the time-dependent approach on the synchrotron lightcurve are investigated here. Taking into account the retardation due to the finite size of the source and the source geometry, we show that the time-dependent synchrotron-self Compton (SSC) cooling still has profound effects on the lightcurve compared to the usual linear (synchrotron and external Compton) cooling terms. This is most obvious if the SSC cooling takes lon...

  17. The synchrotron radiation angiography program at the national synchrotron light source

    International Nuclear Information System (INIS)

    The National Synchrotron Light Source (NSLS) angiography program is under development. The program is a collaboration between the Stanford University Angiography Project and the NSLS. A 180 m2 clinical facility has been built. A beam line is being constructed to utilize a superconducting wiggler radiation source. Projected start-up date for the NSLS program is Summer 1988

  18. Range of applications of modern superconducting synchrotron radiation sources using the source planned at Karlsruhe (KSSQ) as an example

    International Nuclear Information System (INIS)

    The performance of the Karlsruhe synchrotron radiation source which was designed originally for X-ray deep-etch lithography comes close to that of first and second generation synchrotron radiation sources. The range of applications spanned by KSSQ is therefore quite similar to that of those machines. The present report displays a first collection of topics from the fields of surface analysis, solid state and materials research, and biology which could be investigated using KSSQ by interested groups coming from KfK and its surroundings. (orig.)

  19. Regulating spin and Fermi surface topology of a quantum metal film by the surface (interface) monatomic layer

    Science.gov (United States)

    Matsuda, Iwao

    2012-02-01

    Spin and current controls in solids have been one of the central issues in researches of electron and spin transport. Nowadays, electronics/spintronics deals with nanometer- or atomic-scale structures and miniaturization of these systems implies emergence of various quantum phenomena, intimately linked to the formation of electronic states different from those of the corresponding bulk materials. For example, valence electrons of films with the thickness comparable to the electron wavelength form discrete quantum-well states (QWSs) under opportune conditions of confinement (quantum size effect). Furthermore, the size reduction also increases the surface/volume ratio and a film possibly changes its electronic (spin) properties by the surface effect. Concerning metal films, the quantum size effect requires the thickness in a range of nanometers and the length corresponds to several tens of atoms, indicating the very large ratio of a surface (interface) monatomic layer to film atomic layers. Thus, we have been interested in combining the quantum size effects and the surface effect on the metal films to induce new physical phenomena. In the present talk, two research cases are shown. 1) Instead of isotropic two-dimensional in-plane states expected for an isolated metal film, quasi-one-dimensional quantized states were measured by photoemission spectroscopy in an epitaxial Ag(111) ultra thin film, prepared on an array of atomic chains [1]. 2) High-resolution spin-resolved photoemission and magneto-transport experiments of ultrathin Ag(111) films, covered with a /3x/3-Bi/Ag surface ordered alloy, were performed. The surface state (SS) bands, spin-split by the Rashba interaction, selectively couple to the originally spin-degenerate QWS bands in the metal film, making the spin-dependent hybridization [2,3]. Magnetoconductance of the films, measured in situ by the micro-four-point probe method as a function of the applied magnetic field [4], has shown that the formation of

  20. Looking Back at International Synchrotron Radiation Instrumentation

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Gwyn

    2012-03-01

    With the 11th International Synchrotron Radiation Instrumentation coming up in July 2012 in Lyons, France, we thought it might be of interest to our readers to review all the past meetings in this series. We thank Denny Mills of the APS, Argonne for putting the list together. Prior to these larger meetings, and in the early days, facilities held their own meetings similar to the user meetings of today. However, the meeting held at ACO in Orsay, France in 1977 was the first such meeting with an international flavor and so it is on the list. However it is not counted as number 1 since it was agreed way back to start the numbering with the 1982 DESY meeting. The 2005 USA National Meeting scheduled at CAMD in Baton Rouge had to be canceled due to Hurricane Katrina. It was ultimately held in 2007, with the CLS hosted meeting the following year. And a personal note from the magazine - Synchrotron Radiation News was born at the 1987 meeting in Madison, Wisconsin with a proposal that was put to a special session of the meeting organized by Susan Lord. Initial proposals were to model it after the CERN Courier, but it soon adopted its own distinct flavor.

  1. Status of the SOLEIL Booster Synchrotron

    CERN Document Server

    Loulergue, Alexandre

    2005-01-01

    SOLEIL is a 2.75 GeV third generation synchrotron radiation facility under construction near Paris. The injection system is composed of a 100 MeV electron Linac pre-accelerator followed by a full energy (2.75 GeV) booster synchrotron. The booster lattice is based on a FODO structure with missing magnet. With a circumference of 157 m and low field magnets (0.74 T), the emittance is of 150 nm.rad at 2.75 GeV. A flexible and economic ramping switched mode procedure for the main supply cycled up to 3 Hz and a 35 kW-352 MHz solid state amplifier powering the RF system are used. At present time, all the magnets, supports and vacuum have been received and tested. Half of the ring is already assembled and installation is the tunnel will begin in January 05. The pulsed elements and their pulser will be received and tested from January to April. The four main magnet power supplies will be received in February and tested in Marsh. We plan the booster commissioning with beam in May 2005.

  2. Ferroelectrics under the Synchrotron Light: A Review

    Directory of Open Access Journals (Sweden)

    Luis E. Fuentes-Cobas

    2015-12-01

    Full Text Available Currently, an intensive search for high-performance lead-free ferroelectric materials is taking place. ABO3 perovskites (A = Ba, Bi, Ca, K and Na; B = Fe, Nb, Ti, and Zr appear as promising candidates. Understanding the structure–function relationship is mandatory, and, in this field, the roles of long- and short-range crystal orders and interactions are decisive. In this review, recent advances in the global and local characterization of ferroelectric materials by synchrotron light diffraction, scattering and absorption are analyzed. Single- and poly-crystal synchrotron diffraction studies allow high-resolution investigations regarding the long-range average position of ions and subtle global symmetry break-downs. Ferroelectric materials, under the action of electric fields, undergo crystal symmetry, crystallite/domain orientation distribution and strain condition transformations. Methodological aspects of monitoring these processes are discussed. Two-dimensional diffraction clarify larger scale ordering: polycrystal texture is measured from the intensities distribution along the Debye rings. Local order is investigated by diffuse scattering (DS and X-ray absorption fine structure (XAFS experiments. DS provides information about thermal, chemical and displacive low-dimensional disorders. XAFS investigation of ferroelectrics reveals local B-cation off-centering and oxidation state. This technique has the advantage of being element-selective. Representative reports of the mentioned studies are described.

  3. Synchrotron radiation from a Helical Wiggler

    International Nuclear Information System (INIS)

    The use of Wiggler magnets as an improved source of synchrotron radiation from high energy electron storage rings was proposed a few years ago. Since then it has also been suggested that synchrotron radiation from Wiggler magnets placed in proton machines can be used to monitor energy, dimensions and position of the beam and that this effect is even more interesting in proton storage rings where the need to see the beam is greater. Most of the calculations carried out so far consider radiation from a single particle in a Wiggler which is appropriate when the beam is radiating incoherently. In this paper a general formalism is developed for the case when the beam radiates coherently. These results are then applied to both electron and proton storage rings. For the electron case, an expression is derived for the length of the bunch to be used as a more intense coherent radiation source. For proton machines the radiation can be used to measure energy, current, transverse dimensions and longitudinal density variations in the beam

  4. Synchrotrons for hadron therapy: Part I

    CERN Document Server

    Badano, L; Bryant, P; Crescenti, M; Holy, P; Knaus, P; Maier, A; Pullia, M; Rossi, S

    1999-01-01

    The treatment of cancer with accelerator beams has a long history with betatrons, linacs, cyclotrons and now synchrotrons being exploited for this purpose. Treatment techniques can be broadly divided into the use of spread-out beams and scanned 'pencil' beams. The Bragg-peak behaviour of hadrons makes them ideal candidates for the latter. The combination of precisely focused 'pencil' beams with controllable penetration (Bragg peak) and high, radio-biological efficiency (light ions) opens the way to treating the more awkward tumours that are radio-resistant, complex in shape and lodged against critical organs. To accelerate light ions (probably carbon) with pulse-to-pulse energy variation, a synchrotron is the natural choice. The beam scanning system is controlled via an on-line measurement of the particle flux entering the patient and, for this reason, the beam spill must be extended in time (seconds) by a slow-extraction scheme. The quality of the dose intensity profile ultimately depends on the uniformity o...

  5. Synchrotrons for hadron therapy, part 1

    CERN Document Server

    Badano, L; Bryant, P J; Crescenti, M; Holy, P; Knaus, P; Maier, A T; Pullia, M; Rossi, S

    1999-01-01

    The treatment of cancer with accelerator beams has a long history with linacs, cyclotrons and now synchrotrons being exploited for this purpose. Treatment techniques can be broadly divided into the use of spread-out beams and scanned 'pencil' beams. The Bragg-peak behaviour of hadrons makes them ideal candidates for the latter. The combination of precisely focused 'pencil' beams with controllable penetration (Bragg peak) and high, radio-biological efficiency (light ions) opens the way to treating the more awkward tumours that are radio-resistant, complex in shape and lodged against critical organs. To accelerate light ions (probably carbon) with pulse-to-pulse energy variation, a synchrotron is the natural choice. The beam scanning system is controlled via an on-line measurement of the particle flux entering the patient and, for this reason, the beam spill must be extended in time (seconds) by a slow-extraction scheme. The quality of the dose intensity profile ultimately depends on the uniformity of the beam ...

  6. Improvements in the rapid cycling synchrotron

    International Nuclear Information System (INIS)

    The Rapid Cycling Snychrotron1 (RCS), originally designed as an injection energy booster for the Zero Gradient Synchrotron (ZGS), operated under constraints imposed by ZGS operation until December 1979. Once these restraints were removed, the RCS made rapid strides toward its nearterm goals of 8 μA of protons for Argonne National Laboratory's (ANL) Intense Pulsed Neutron Source (IPNS) program. Reliable 30 Hz operation was achieved in the spring of 1980 with beams as high as 2 x 1012 protons per pulse and weekly average intensities of over 6 μA on target. These gains resulted from better injection matching, more efficient RF turn-on and dynamic chromaticity control. A high intensity small diameter synchrotron, such as the RCS, has special problems with loss control which dictate prudence during intensity improvement activities. Additional improvements were made to the machine starting in August of 1980 while the extraction magnets were relocated for operation with the IPNS-I target. These improvements have now been completed. Startup of the accelerator is now underway, and it is clear that these modifications have resulted in a radioactively cleaner operation. It is too early to evaluate the effects of the improvements on intensity and reliability, but a single pulse extracted intensity of 2.4 x 1012 protons has been achieved, a 20% increase. The studies and equipment leading to the intensity gains are discussed. (orig.)

  7. Berkeley Lab's ALS generates femtosecond synchrotron radiation

    CERN Document Server

    Robinson, A L

    2000-01-01

    A team at Berkeley's Advanced Light Source has shown how a laser time-slicing technique provides a path to experiments with ultrafast time resolution. A Lawrence Berkeley National Laboratory team has succeeded in generating 300 fs pulses of synchrotron radiation at the ALS synchrotron radiation machine. The team's members come from the Materials Sciences Division (MSD), the Center for Beam Physics in the Accelerator and Fusion Research Division and the Advanced Light Source (ALS). Although this proof-of principle experiment made use of visible light on a borrowed beamline, the laser "time-slicing" technique at the heart of the demonstration will soon be applied in a new bend magnet beamline that was designed specially for the production of femtosecond pulses of X-rays to study long-range and local order in condensed matter with ultrafast time resolution. An undulator beamline based on the same technique has been proposed that will dramatically increase the flux and brightness. The use of X-rays to study the c...

  8. Application of circular polarized synchrotron radiation

    International Nuclear Information System (INIS)

    The idea of using the polarizing property of light for physical experiment by controlling it variously has been known from old time, and the Faraday effect and the research by polarizing microscopy are its examples. The light emitted from the electron orbit of an accelerator has the different polarizing characteristics from those of the light of a laboratory light source, and as far as observing it within the electron orbit plane, it becomes linearly polarized light. By utilizing this property well, research is carried out at present in synchrotron experimental facilities. Recently, the technology related to the insert type light cources using permanent magnets has advanced remarkably, and circular polarized light has become to be producible. If the light like this can be obtained with the energy not only in far ultraviolet region but also to x-ray region at high luminance, new possibility should open. At the stage that the design of an insert type light source was finished, and its manufacture was started, the research on the method of evaluating the degree of circular polarization and the research on the utilization of circular polarized synchrotron radiation are earnestly carried out. In this report, the results of researches presented at the study meeting are summarized. Moreover, the design and manufacture of the beam lines for exclusive use will be carried out. (Kako, I.)

  9. Mapping prehistoric ghosts in the synchrotron

    Energy Technology Data Exchange (ETDEWEB)

    Edwards, N.P.; Wogelius, R.A. [University of Manchester, School of Earth, Atmospheric, and Environmental Sciences, Manchester (United Kingdom); University of Manchester, Williamson Research Centre for Molecular Environmental Science, Manchester (United Kingdom); Bergmann, U. [SLAC National Accelerator Laboratory, Linac Coherent Light Source, Menlo Park, CA (United States); Larson, P. [Black Hills Institute of Geological Research, Inc., Hill City, SD (United States); Sellers, W.I. [University of Manchester, Faculty of Life Sciences, Manchester (United Kingdom); Manning, P.L. [University of Manchester, School of Earth, Atmospheric, and Environmental Sciences, Manchester (United Kingdom); University of Manchester, Williamson Research Centre for Molecular Environmental Science, Manchester (United Kingdom); University of Pennsylvania, Department of Earth and Environmental Science, Philadelphia, PA (United States)

    2013-04-15

    The detailed chemical analysis of fossils has the potential to reveal great insight to the composition, preservation and biochemistry of ancient life. Such analyses would ideally identify, quantify, and spatially resolve the chemical composition of preserved bone and soft tissue structures, but also the embedding matrix. Mapping the chemistry of a fossil in situ can place constraints on mass transfer between the enclosing matrix and the preserved organism(s), and therefore aid in distinguishing taphonomic processes from original chemical zonation remnant within the fossils themselves. Conventional analytical methods, such as scanning electron microscopy (SEM) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) have serious limitations in this case, primarily, an inability to provide large (i.e., decimeter) scale chemical maps. Additionally, vacuum chamber size and the need for destructive sampling preclude analysis of large and precious fossil specimens. However, the recent development of Synchrotron Rapid Scanning X-ray Fluorescence (SRS-XRF) at the Stanford Synchrotron Radiation Lightsource (SSRL) allows the non-destructive chemical analysis and imaging of major, minor, and trace element concentrations of large paleontological and archeological specimens in rapid scanning times. Here we present elemental maps of a fossil reptile produced using the new SRS-XRF method. Our results unequivocally show that preserved biological structures are not simply impressions or carbonized remains, but possess a remnant of the original organismal biochemistry. We show that SRS-XRF is a powerful new tool for the study of paleontological and archaeological samples. (orig.)

  10. Physics design of SSRF synchrotron radiation security

    Institute of Scientific and Technical Information of China (English)

    XU Yi; DAI Zhi-Min; LIU Gui-Min

    2009-01-01

    High brightness of SSRF brings about synchrotron radiation security problems,which will be solved in physics design.The main radiations are generated from bending magnets and insertion devices.Since the fact that radiation power and radiating area are different in these two kinds of synchrotron radiation,the arrangements of photon absorbers,diaphragms and other vacuum components need to be treated distinctively.In addition.SSRF interlock protection threshold is defined and the beam orbit in the straight line is limited.Hence.beam orbit in the bending magnets and IDs are also restricted by the threshold.The orbit restriction is calculated and helps us to arrange the vacuum components.In this paper,beam orbit distortion restricted by interlock protection threshold,radiation power,radiation angle and illuminating area are calculated.From the calculation results,the physics designs in manufacture and installation vacuum components are put forward.By commissioning,it is shown that physics requirements are met rigidly in the engineering process.

  11. Synchrotron Facilities and Free Electron Lasers

    Energy Technology Data Exchange (ETDEWEB)

    Vaclav, Vylet; /Duke U.; Liu, James; /SLAC

    2007-12-21

    Synchrotron radiation (SR) is electromagnetic radiation emitted when a charged particle travels along a curved trajectory. Initially encountered as a nuisance around orbits of high energy synchrotron accelerators, it gradually became an indispensable research tool in many applications: crystallography, X-ray lithography, micromechanics, structural biology, microprobe X-ray experiments, etc. So-called first generation SR sources were exploiting SR in parasitic mode at electron accelerators built to study particle collisions. The second generation of SR sources was the first facilities solely devoted to SR production. They were optimized to achieve stable high currents in the accelerator ring to achieve substantially higher photon flux and to provide a large number of SR beam lines for users. Third generation sources were further optimized for increased brilliance, i.e. with photons densely packed into a beam of very small cross-sectional area and minimal angular divergence (see the Appendix for more detailed definitions of flux, brightness and brilliance) and makes extensive use of the insertion devices such as wigglers and undulators. Free Electron Lasers (FELs), the fourth generation SR sources, open new research possibilities by offering extremely short pulses of extremely bright and coherent radiation. The number of SR sources around the world now probably exceeds 100. These facilities vary greatly in size, energy of the electron (or positron) beams, range of photon energies and other characteristics of the photon beams produced. In what follows we will concentrate on describing some common aspects of SR facilities, their operation modes and specific radiation protection aspects.

  12. Performances of BNL high-intensity synchrotrons

    International Nuclear Information System (INIS)

    The AGS proton synchrotron was completed in 1960 with initial intensity in the 10 to the 10th power proton per pulse (ppp) range. Over the years, through many upgrades and improvements, the AGS now reached an intensity record of 6.3 x 1013 ppp, the highest world intensity record for a proton synchrotron on a single pulse basis. At the same time, the Booster reached 2.2 x 1013 ppp surpassing the design goal of 1.5 x 1013 ppp due to the introduction of second harmonic cavity during injection. The intensity limitation caused by space charge tune spread and its relationship to injection energy at 50 MeV, 200 MeV, and 1,500 MeV will be presented as well as many critical accelerator manipulations. BNL currently participates in the design of an accumulator ring for the SNS project at Oak Ridge. The status on the issues of halo formation, beam losses and collimation are also presented

  13. Organic adsorbates on metal surfaces. PTCDA and NTCDA on AG(110)

    Energy Technology Data Exchange (ETDEWEB)

    Abbasi, Afshin

    2010-02-22

    , the inclusion of the major part of the attractive van-der-Waals interaction brings the adsorbate back to an arrangement close to parallel to the substrate, with very small differences in height between the different subunits. With respect to experimental data obtained on Ag(111), the calculated distance between adsorbate and substrate is somewhat smaller, indicating that the open Ag(110) surface interacts more strongly with the organic compounds. This is consistent with the fact that only Ag(110) induces a brickwall unit cell of the adsorbate, a clear sign for a particularly large adsorption energy. The resulting model geometries are analysed in terms of cohesive energy, Mulliken charges, core level shifts, and vibrational properties. (orig.)

  14. For the first time: Moessbauer effect with synchrotron radiation

    International Nuclear Information System (INIS)

    After 9 years of preparation a group of scientists under the leadership of Prof. Erich Gerdau from the University of Hamburg succeeded in observing the Moessbauer Effect (recoilless emission of a gamma quantum) with the help of synchrotron radiation in October last year. The experiments were carried out at the Hamburg Synchrotron Radiation Laboratory, HASYLAB, at the DORIS II storage ring. (orig.)

  15. Synchrotron radiation in art and archaeology SRA 2005

    Energy Technology Data Exchange (ETDEWEB)

    Pollard, A.M.; Janssens, K.; Artioli, G.; Young, M.L.; Casadio, F.; Schnepp, S.; Marvin, J.; Dunand, D.C.; Almer, J.; Fezzaa, K.; Lee, W.K.; Haeffner, D.R.; Reguer, S.; Dillmann, Ph.; Mirambet, F.; Susini, J.; Lagarde, P.; Pradell, T.; Molera, J.; Brunetti, B.; D' acapito, F.; Maurizio, C.; Mazzoldi, P.; Padovani, S.; Sgamellotti, A.; Garges, F.; Etcheverry, M.P.; Flank, A.M.; Lagarde, P.; Marcus, M.A.; Scheidegger, A.M.; Grolimund, D.; Pallot-Frossard, I.; Smith, A.D.; Jones, M.; Gliozzo, E.; Memmi-Turbanti, I.; Molera, J.; Vendrell, M.; Mcconachie, G.; Skinner, T.; Kirkman, I.W.; Pantos, E.; Wallert, A.; Kanngiesser, B.; Hahn, O.; Wilke, M.; NekaT, B.; Malzer, W.; Erko, A.; Chalmin, E.; Vignaud, C.; Farges, F.; Susini, J.; Menu, M.; Sandstrom, M.; Cotte, M.; Kennedy, C.J.; Wess, T.J.; Muller, M.; Murphy, B.; Roberts, M.A.; Burghammer, M.; Riekel, C.; Gunneweg, J.; Pantos, E.; Dik, J.; Tafforeau, P.; Boistel, R.; Boller, E.; Bravin, A.; Brunet, M.; Chaimanee, Y.; Cloetens, P.; Feist, M.; Hoszowska, J.; Jaeger, J.J.; Kay, R.F.; Lazzari, V.; Marivaux, L.; Nel, A.; Nemoz, C.; Thibault, X.; Vignaud, P.; Zabler, S.; Sciau, P.; Goudeau, P.; Tamura, N.; Doormee, E.; Kockelmann, W.; Adriaens, A.; Ryck, I. de; Leyssens, K.; Hochleitner, B.; Schreiner, M.; Drakopoulos, M.; Snigireva, I.; Snigirev, A.; Sanchez Del Rio, M.; Martinetto, P.; Dooryhee, E.; Suarez, M.; Sodo, A.; Reyes-Valerio, C.; Haro Poniatowski, E.; Picquart, M.; Lima, E.; Reguera, E.; Gunneweg, J.; Reiche, I.; Berger, A.; Bevers, H.; Duval, A

    2005-07-01

    Materials - bones, artifacts, artwork,.... - lie at the heart of both archaeology and art conservation. Synchrotron radiation techniques provide powerful ways to interrogate these records of our physical and cultural past. In this workshop we will discuss and explore the current and potential applications of synchrotron radiation science to problems in archaeology and art conservation. This document gathers the abstracts of the presentations.

  16. A synchrotron radiation facility for x-ray astronomy

    DEFF Research Database (Denmark)

    Hall, C.J.; Lewis, R.A.; Christensen, Finn Erland;

    1997-01-01

    A proposal for an x-ray optics test facility based at a synchrotron radiation source is presented. The facility would incorporate a clean preparation area, and a large evacuable test area. The advantages of using a synchrotron as the source of the test radiation are discussed. These include the a...

  17. Synchrotron radiation in art and archaeology SRA 2005

    International Nuclear Information System (INIS)

    Materials - bones, artifacts, artwork,.... - lie at the heart of both archaeology and art conservation. Synchrotron radiation techniques provide powerful ways to interrogate these records of our physical and cultural past. In this workshop we will discuss and explore the current and potential applications of synchrotron radiation science to problems in archaeology and art conservation. This document gathers the abstracts of the presentations

  18. Microstructure of Cu-Ag Uniform Nanoparticulate Films on Polyurethane 3D Catheters: Surface Properties.

    Science.gov (United States)

    Rtimi, Sami; Sanjines, Rosendo; Pulgarin, Cesar; Kiwi, John

    2016-01-13

    The preparation, characterization, and antibacterial testing of Cu-Ag sputtered polyurethane (PU) catheters are addressed in this study. PU catheters with different atomic ratios Cu:Ag have been sputtered and led to different optical properties as followed by diffuse reflectance spectroscopy (DRS) and the surface redox properties were also different for different Cu-Ag ratios as observed by X-ray photoelectron spectroscopy (XPS). The surface atomic percentage concentration of the oxidized/reduced C-species originating from bacterial cultures before and after bacterial inactivation were determined on the Cu-Ag PU catheters. The crystallographic properties were determined by X-ray diffraction (XRD). The XRD-diffractogram showed the presence of Cu2O (111), Cu (200), CuO (020), and Ag (111) indicating that Cu nanoparticles present a more crystalline character compared to Ag nanoparticles. Increasing the percentage of Ag in the Cu-Ag films, bigger Ag-particle agglomerates were detected by scanning transmission electron microscopy (STEM) microanalysis confirming the results obtained by AFM. The bacterial inactivation kinetics of the sputtered Cu-Ag films on PU catheters was investigated in detail. Quasi-instantaneous bacterial inactivation kinetics was induced by the sputtered films on PU catheters after optimization of the Cu-Ag film thickness. PMID:26700113

  19. X-ray and synchrotron studies of porous silicon

    International Nuclear Information System (INIS)

    The results of comprehensive studies of layers of porous silicon of different conductivity types, grown by anodizing standard Si(111) substrates in an electrolyte based on fluoric acid and ethanol with the addition of 5% of iodine and kept in air for a long time, are discussed. Measurements are performed by scanning electron microscopy, high-resolution X-ray diffraction, and ultrasoft X-ray spectroscopy using synchrotron radiation. The structural parameters of the layers (thickness, strain, and porosity) and atomic and chemical composition of the porous-silicon surface are determined. It is found that an oxide layer 1.5–2.3-nm thick is formed on the surface of the silicon skeleton. The near-edge fine structure of the Si 2p absorption spectrum of this layer corresponds to the fine structure of the 2p spectrum of well coordinated SiO2. In this case, the fine structure in the Si 2p-edge absorption region of the silicon skeleton is identical to that of the 2p absorption spectrum of crystalline silicon

  20. Synchrotron topographic project. Progress report, February 20, 1981-January 20, 1982

    International Nuclear Information System (INIS)

    The Synchrotron Topography Project (STP) has under design and construction various phases of a dedicated beam line for x-ray diffraction topography users in conjunction with the National Synchrotron Light Source at Brookhaven National Laboratory. During the past year final design and procurement phase has been completed for the following: (1) Experimental Hutch, (2) White Beam Camera, (3) Detector Arm for White Beam Camera, (4) Film Cassette System, (5) Medium Resolution Real-time TV System, (6) Lift Table Assembly, (7) Asymmetric Camera Base Mount, (8) Motor Control System, and (9) Computer system. Experimental work has been initiated on using reflection topography to study fracture surfaces. Preliminary results, both with Berg-Barrett, as well as with Synchrotron Topography done in collaboration with the Daresbury, U.K. facility show that defects generated in the near surface layers can be detected. Research work on the effects of stress concentration and geometric effects due to grain boundaries on the fracture of tungsten has been completed

  1. Synchrotron-Based in Situ Characterization of the Scaffold Mass Loss from Erosion Degradation.

    Science.gov (United States)

    Bawolin, Nahshon K; Chen, Xiongbaio

    2016-01-01

    The mass loss behavior of degradable tissue scaffolds is critical to their lifespan and other degradation-related properties including mechanical strength and mass transport characteristics. This paper presents a novel method based on synchrotron imaging to characterize the scaffold mass loss from erosion degradation in situ, or without the need of extracting scaffolds once implanted. Specifically, the surface-eroding degradation of scaffolds in a degrading medium was monitored in situ by synchrotron-based imaging; and the time-dependent geometry of scaffolds captured by images was then employed to estimate their mass loss with time, based on the mathematical model that was adopted from the literature of surface erosion with the experimentally-identified model parameters. Acceptable agreement between experimental results and model predictions was observed for scaffolds in a cylindrical shape, made from poly(lactic-co-glycolic) acid (PLGA) and polycaprolactone (PCL). This study illustrates that geometry evaluation by synchrotron-based imaging is an effective means to in situ characterize the scaffold mass loss as well as possibly other degradation-related properties. PMID:27399789

  2. Synchrotron-Based in Situ Characterization of the Scaffold Mass Loss from Erosion Degradation

    Directory of Open Access Journals (Sweden)

    Nahshon K. Bawolin

    2016-07-01

    Full Text Available The mass loss behavior of degradable tissue scaffolds is critical to their lifespan and other degradation-related properties including mechanical strength and mass transport characteristics. This paper presents a novel method based on synchrotron imaging to characterize the scaffold mass loss from erosion degradation in situ, or without the need of extracting scaffolds once implanted. Specifically, the surface-eroding degradation of scaffolds in a degrading medium was monitored in situ by synchrotron-based imaging; and the time-dependent geometry of scaffolds captured by images was then employed to estimate their mass loss with time, based on the mathematical model that was adopted from the literature of surface erosion with the experimentally-identified model parameters. Acceptable agreement between experimental results and model predictions was observed for scaffolds in a cylindrical shape, made from poly(lactic-co-glycolic acid (PLGA and polycaprolactone (PCL. This study illustrates that geometry evaluation by synchrotron-based imaging is an effective means to in situ characterize the scaffold mass loss as well as possibly other degradation-related properties.

  3. Synchrotron based mass spectrometry to investigate the molecular properties of mineral-organic associations

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Suet Yi; Kleber, Markus; Takahashi, Lynelle K.; Nico, Peter; Keiluweit, Marco; Ahmed, Musahid

    2013-04-01

    Soil organic matter (OM) is important because its decay drives life processes in the biosphere. Analysis of organic compounds in geological systems is difficult because of their intimate association with mineral surfaces. To date there is no procedure capable of quantitatively separating organic from mineral phases without creating artifacts or mass loss. Therefore, analytical techniques that can (a) generate information about both organic and mineral phases simultaneously and (b) allow the examination of predetermined high-interest regions of the sample as opposed to conventional bulk analytical techniques are valuable. Laser Desorption Synchrotron Postionization (synchrotron-LDPI) mass spectrometry is introduced as a novel analytical tool to characterize the molecular properties of organic compounds in mineral-organic samples from terrestrial systems, and it is demonstrated that when combined with Secondary Ion Mass Spectrometry (SIMS), can provide complementary information on mineral composition. Mass spectrometry along a decomposition gradient in density fractions, verifies the consistency of our results with bulk analytical techniques. We further demonstrate that by changing laser and photoionization energies, variations in molecular stability of organic compounds associated with mineral surfaces can be determined. The combination of synchrotron-LDPI and SIMS shows that the energetic conditions involved in desorption and ionization of organic matter may be a greater determinant of mass spectral signatures than the inherent molecular structure of the organic compounds investigated. The latter has implications for molecular models of natural organic matter that are based on mass spectrometric information.

  4. Note: Dynamic strain field mapping with synchrotron X-ray digital image correlation

    International Nuclear Information System (INIS)

    We present a dynamic strain field mapping method based on synchrotron X-ray digital image correlation (XDIC). Synchrotron X-ray sources are advantageous for imaging with exceptional spatial and temporal resolutions, and X-ray speckles can be produced either from surface roughness or internal inhomogeneities. Combining speckled X-ray imaging with DIC allows one to map strain fields with high resolutions. Based on experiments on void growth in Al and deformation of a granular material during Kolsky bar/gas gun loading at the Advanced Photon Source beamline 32ID, we demonstrate the feasibility of dynamic XDIC. XDIC is particularly useful for dynamic, in-volume, measurements on opaque materials under high strain-rate, large, deformation

  5. Exploratory investigation of color changes in paints induced by broadband synchrotron radiation

    International Nuclear Information System (INIS)

    Changes in color of coated (painted) aluminum surfaces exposed to broad-band synchrotron radiation (10-2000 eV) are investigated as a function of radiation dose (N). Quantitative color differences (ΔEab*) before and after the exposure are obtained from spectral diffuse reflectance measurements using the standard CIELAB formula. The results indicate that the dose-response curve of the color-coated surfaces at large photon doses can be described as ΔEab* ≅ e-d/N where d is a material-dependent constant. (author)

  6. Laser-synchrotron studies of the dynamics of UV-photon-stimulated desorption in alkali halides

    International Nuclear Information System (INIS)

    Laser-synchrotron studies of neutral alkali emission from alkali halide crystals are yielding new insights into the dynamics of energy absorption, energy localization and bond-breaking in photon-stimulated desorption. The ground-state neutral desorption is triggered by the thermal diffusion of photon-induced electronic defects; however, the excited-state neutral alkalis are formed in a surface-specific process on an extremely short time scale. In addition, there is new evidence for a surface overlayer which retards substrate desorption, thus suggesting a new approach to the optical damage problem at ultraviolet wavelengths. 8 references

  7. Laser-synchrotron studies of the dynamics of UV-photon-stimulated desorption in alkali halides

    International Nuclear Information System (INIS)

    Laser-synchrotron studies of neutral alkali emission from alkali halide crystals are yielding new insights into the dynamics of energy absorption, energy localization and bond-breaking in photon-stimulated desorption. The ground-state neutral desorption is triggered by thermal diffusion of photon-induced electronic defects; however, the excited-state neutral alkalis are formed in a surface-specific process on an extremely short time scale. In addition, there is new evidence for a surface overlayer which retards substrate desorption, thus suggesting a new approach to the optical damage problem at ultraviolet wavelengths

  8. Soft X-ray synchrotron radiation photoemission study on uranium compounds

    International Nuclear Information System (INIS)

    We have carried out the angle-resolved photoemission experiments on some uranium compounds using soft X-ray synchrotron radiation. Bulk- and U 5f-sensitive band structure and Fermi surface were obtained for paramagnetic uranium compound UFeGa5. Although the agreement between the experimental band structure and the LDA calculation treating U 5f electrons as being itinerant is qualitative, the topology of the Fermi surface is well explained by the calculation, suggesting that the U 5f states can be essentially understood within the itinerant-electron model

  9. Quadrupole magnet for a rapid cycling synchrotron

    International Nuclear Information System (INIS)

    Rapid Cycling Synchrotrons (RCS) feature interleaved warm and cold dipole magnets; the field of the warm magnets is used to modulate the average bending field depending on the particle energy. It has been shown that RCS can be an attractive option for fast acceleration of particles, for example, muons, which decay quickly. In previous studies it was demonstrated that in principle warm dipole magnets can be designed which can provide the required ramp rates, which are equivalent to frequencies of about 1 kHz. To reduce the losses it is beneficial to employ two separate materials for the yoke; it was also shown that by employing an optimized excitation coil geometry the eddy current losses are acceptable. In this paper we show that the same principles can be applied to quadrupole magnets targeting 30 T/m with a repetition rate of 1kHz and good field quality.

  10. Quadrupole magnet for a rapid cycling synchrotron

    Energy Technology Data Exchange (ETDEWEB)

    Witte, H. [Brookhaven National Lab. (BNL), Upton, NY (United States); Berg, J. S. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2015-05-03

    Rapid Cycling Synchrotrons (RCS) feature interleaved warm and cold dipole magnets; the field of the warm magnets is used to modulate the average bending field depending on the particle energy. It has been shown that RCS can be an attractive option for fast acceleration of particles, for example, muons, which decay quickly. In previous studies it was demonstrated that in principle warm dipole magnets can be designed which can provide the required ramp rates, which are equivalent to frequencies of about 1 kHz. To reduce the losses it is beneficial to employ two separate materials for the yoke; it was also shown that by employing an optimized excitation coil geometry the eddy current losses are acceptable. In this paper we show that the same principles can be applied to quadrupole magnets targeting 30 T/m with a repetition rate of 1kHz and good field quality.

  11. New Synchrotron Radiation Center beamlines at Aladdin

    International Nuclear Information System (INIS)

    In the past year, the Synchrotron Radiation Center (SRC) staff has installed five new beamlines at SRC. Three of these beamlines are ''public'' beamlines operated by SRC for experiments selected from peer-reviewed proposals. Fifty to seventy-five percent of the experimental time on the other two beamlines is managed by the SRC as a consequence of the SRC being a partner in participating research teams (PRTs). These new beamlines bring the number of VUV and soft x-ray research beamlines installed on Aladdin to 17 as of August 1988. Including two storage ring optical diagnostic ports, there will be 20 ports in use on Aladdin by the end of 1988

  12. Coherent synchrotron radiation experiments for the LCLS

    International Nuclear Information System (INIS)

    The authors describe a coherent synchrotron radiation experiment planned at Los Alamos to support the design of the Linac Coherent Light Source (LCLS) x-ray FEL. Preliminary simulations of the LCLS compressors show that a clever tuning strategy can be used to minimize the electron's beam emittance growth due to noninertial space-charge forces by employing a delicate cancellation of these forces. The purpose of the Los Alamos experiment, using a sub-picosecond chicane compressor, is to benchmark these simulations tools. In this paper, the authors present detailed numerical simulations of the experiment, and point out unique signatures of this effect that are measurable. As predicted previously, the largest emittance growths and induced energy spreads result from the nonradiative components of this space-charge force

  13. Synchrotron radiation techniques. Extension to magnetism research

    International Nuclear Information System (INIS)

    Recently developed techniques using synchrotron radiation for the study of magnetism are reviewed. These techniques are based on X-ray absorption spectroscopy (XAS), and they exhibit significant advantages in element specificity. This is very important since the most attractive magnetic materials contain many magnetic elements, and those with small magnetic moments often play an essential role in the magnetic properties. Circularly polarized X-rays emitted from bending magnets or helical undulators allow us to perform magnetic circular dichroism measurements to reveal microscopic magnetic properties of various kinds of magnetic materials. X-ray absorption magnetic circular dichroism (XMCD) is discussed in detail. This technique provides unique information on orbital magnetic moments as well as spin magnetic moments, which are useful for the study of magnetic anisotropy. X-ray magnetic linear dichroism (XMLD) and X-ray resonant magnetic reflectometry (XRMR) techniques are also described. (author)

  14. Application of synchrotron radiation to submicron lithography

    International Nuclear Information System (INIS)

    Relevant features of modern X-ray sources suitable for submicron lithography with special emphasis on synchrotron with classical, normal and superconducting storage rings are compared. Capability of such sources for X-ray lithographic fabrication of 100 nm lines and 0.5 micron devices such as ULSI and multimegabit memory are discussed. Selecting the materials for X-ray mask substrate as well as the technique of patterning absorber material over it are extremely critical. Use of advanced techniques such as reactive ion etching, ion beam patterning and electron beam lithography for their fabrication is discussed. Characteristics of positive/negative X-ray resists such as sensitivity and resolution, critically governing their suitability in lithographic applications are compared. The technology of alignments recently adopted for X-ray lithography is presented. Submicron patterns and devices like CMOS, BPF and deep grooves featured through dedicated and commercial X-ray systems have been sampled. (author). 5 refs., 2 figs., 2 tabs

  15. Discussion on spin-flip synchrotron radiation

    CERN Document Server

    Bordovitsyn, V A; Myagkii, A N

    1998-01-01

    Quantum spin-flip transitions are of great importance in the synchrotron radiation theory. For better understanding of the nature of this phenomenon, it is necessary to except the effects connected with the electric charge radiation from observation. This fact explains the suggested choice of the spin-flip radiation model in the form of radiation of the electric neutral Dirac-Pauli particle moving in the homogeneous magnetic field. It is known that in this case, the total radiation in the quantum theory is conditioned by spin-flip transitions. The idea is that spin-flip radiation is represented as a nonstationary process connected with spin precession. We shall shown how to construct a solution of the classical equation of the spin precession in the BMT theory having the exact solution of the Dirac-Pauli equation.Thus, one will find the connection of the quantum spin-flip transitions with classical spin precession.

  16. Status of Hiroshima Synchrotron Radiation Center

    International Nuclear Information System (INIS)

    The HSRC is a synchrotron radiation facility of Hiroshima University established in 1996. The HiSOR is a compact racetrack-type storage ring having 21.95 m circumference, therefore its natural emittance of 400 nmrad is not so small compared with the other medium ∼ large storage rings. The most outstanding advantage of the facility lies in good combination with beamlines for high-resolution photoelectron spectroscopy in energy range in VUV ∼ soft X-ray. We report the operation status of HiSOR and the present status of beamlines and experimental stations. The user time last year was achieved 1541 hours which was at the same level with those in the past several years because there was no serious trouble. (author)

  17. Synchrotron radiation — 1873 to 1947

    Science.gov (United States)

    Blewett, John P.

    1988-04-01

    In 1873 Maxwell's treatise "Electricity and Magnetism" made it clear that a changing electric current will emit electromagnetic radiation. By the turn of the century, J.J. Thomson was showing that currents in space could be carried by electrons; accordingly, it was reasonable to believe that electrons, when accelerated, would radiate. By 1912, the theory of radiation from accelerated electrons was worked out and buried in the literature. Radiation from accelerated relativistic electrons did not come into prominence again until the 1940's when, finally, it was observed at the Research Laboratory of the General Electric Company. This paper will discuss the early theoretical treatments and will describe the first observations with the G.E. 100 MeV betatron and 75 MeV synchrotron.

  18. A Thick Target for Synchrotrons and Betatrons

    Science.gov (United States)

    McMillan, E. M.

    1950-09-19

    If a wide x-ray beam from an electron synchrotron or betatron is desired, in radiographic work with large objects for example, the usually very thin target may be replaced by a thick one, provided the resulting distortion of the x-ray spectrum due to multiple radiative processes is permissible. It is difficult to make the circulating electron beam traverse a thick target directly because of the small spacing between successive turns. Mounting a very thin beryllium, or other low-z material, fin on the edge of the thick target so that the fin projects into the beam will cause the beam to lose sufficient energy, and therefore radium, to strike the thick target the next time around. Sample design calculations are given.

  19. A program for synchrotron radiation dose calculations

    International Nuclear Information System (INIS)

    The computer program PHOTON was obtained from Brookhaven National Laboratory (courtesy D. Chapman, NSLS), and has now been installed at APS VAX. In the following a brief description of the program and how to access to it is described with an example. A detailed manual for the program is also available. The program is developed to calculate the transmitted and scattered spectra of the synchrotron radiation, as it passes through series of filters. The source can be a bending magnet or a wiggler. This can be generated for any bending magnet or a wiggler source by varying ring energy, the critical energy and opening angles of the radiation beam. Monochromatic beams to white radiation can be treated. Filter materials can be pure elements or composites. The absorption cross-sections of all elements for covering 10-2 to 106 keV are now included in a table, which can be accessed by giving the atomic symbol

  20. Application of synchrotron radiation in archaeology

    International Nuclear Information System (INIS)

    This paper reports current status of archaeological application of synchrotron radiation (SR). The advantages of SR in archaeological research and various application possibilities of X-ray powder diffraction (XPD), X-ray fluorescence (XRF) and X-ray absorption fine structure (XAFS) analyses of objects and materials of cultural heritage value are demonstrated through a number of case studies from literatures. They include XPD characterizations of Egyptian cosmetic powder, Attic Black Gloss, and pigments in Gothic altarpieces, provenance analysis of Old-Kutani china wares by high energy XRF, and XAFS analyses to reveal to origin of red color in Satsuma copper-ruby glass and role of iron in Maya blue. (author)

  1. Brightness of synchrotron radiation from wigglers

    CERN Document Server

    Geloni, Gianluca; Saldin, Evgeni

    2014-01-01

    According to literature, while calculating the brightness of synchrotron radiation from wigglers, one needs to account for the so called `depth-of-field' effects. In fact, the particle beam cross section varies along the wiggler. It is usually stated that the effective photon source size increases accordingly, while the brightness is reduced. Here we claim that this is a misconception originating from an analysis of the wiggler source based on geometrical arguments, regarded as almost self-evident. According to electrodynamics, depth-of-field effects do not exist: we demonstrate this statement both theoretically and numerically, using a well-known first-principle computer code. This fact shows that under the usually accepted approximations, the description of the wiggler brightness turns out to be inconsistent even qualitatively. Therefore, there is a need for a well-defined procedure for computing the brightness from a wiggler source. We accomplish this task based on the use of a Wigner function formalism. I...

  2. Helical magnetized wiggler for synchrotron radiation laser

    International Nuclear Information System (INIS)

    A helical magnetized iron wiggler has been built for a novel infrared synchrotron radiation laser (SRL) experiment. The wiggler consists of four periods of helical iron structure immersed in a solenoid field. This wiggler is to impart transverse velocity to a prebunched 6 MeV electron beam, and thus to obtain a desired high orbit pitch ratio for the SRL. Field tapering at beam entrance is considered and tested on a similar wiggler. Analytic and simulated characteristics of wigglers of this type are discussed and the performance of the fabricated wigglers is demonstrated experimentally. A 4.7 kG peak field was measured for a 6.4 mm air gap and a 5.4 cm wiggler period at a 20 kG solenoid field. The measured helical fields compare favorably with the analytical solution. This type of helical iron wigglers has the potential to be scaled to small periods with strong field amplitude

  3. Helical magnetized wiggler for synchrotron radiation laser

    CERN Document Server

    Wang Mei; Hirshfield, J L

    1999-01-01

    A helical magnetized iron wiggler has been built for a novel infrared synchrotron radiation laser (SRL) experiment. The wiggler consists of four periods of helical iron structure immersed in a solenoid field. This wiggler is to impart transverse velocity to a prebunched 6 MeV electron beam, and thus to obtain a desired high orbit pitch ratio for the SRL. Field tapering at beam entrance is considered and tested on a similar wiggler. Analytic and simulated characteristics of wigglers of this type are discussed and the performance of the fabricated wigglers is demonstrated experimentally. A 4.7 kG peak field was measured for a 6.4 mm air gap and a 5.4 cm wiggler period at a 20 kG solenoid field. The measured helical fields compare favorably with the analytical solution. This type of helical iron wigglers has the potential to be scaled to small periods with strong field amplitude.

  4. Control system for a compact synchrotron

    International Nuclear Information System (INIS)

    The control system for a compact superconducting synchrotron (HELIOS) is described. The machine is intended to be used as a prototype production tool for X-ray lithography, so emphasis has been placed on engineering the control system for this purpose. The system has been designed to be flexible for commissioning, but easy to use for an operator at a lithography facility. With this in mind the following facilities have been included: keys to limit control functions, a HELP facility for operators, colour touch-panels and displays, limits and other software protection. The conservative hardware design is based on well established CAMAC interfaces. Similarly, the software runs on a MicroVAX with VMS, is written in FORTRAN 77, and is adapted from a well developed SLAC control system. Design features include the use of local intelligence for some subsystems, modular hardware and software, interlocks and a central database. (orig.)

  5. Liquid metal cooling of synchrotron optics

    International Nuclear Information System (INIS)

    The installation of insertion devices at existing synchrotron facilities around the world has stimulated the development of new ways to cool the optical elements in the associated x-ray beamlines. Argonne has been a leader in the development of liquid metal cooling for high heat load x-ray optics for the next generation of synchrotron facilities. The high thermal conductivity, high volume specific heat, low kinematic viscosity, and large working temperature range make liquid metals a very efficient heat transfer fluid. A wide range of liquid metals were considered in the initial phase of this work. The most promising liquid metal cooling fluid identified to date is liquid gallium, which appears to have all the desired properties and the fewest number of undesired features of the liquid metals examined. Besides the special features of liquid metals that make them good heat transfer fluids, the very low vapor pressure over a large working temperature range make liquid gallium an ideal cooling fluid for use in a high vacuum environment. A leak of the liquid gallium into the high vacuum and even into very high vacuum areas will not result in any detectable vapor pressure and may even improve the vacuum environment as the liquid gallium combines with any water vapor or oxygen present in the system. The practical use of a liquid metal for cooling silicon crystals and other high heat load applications depends on having a convenient and efficient delivery system. The requirements for a typical cooling system for a silicon crystal used in a monochromator are pumping speeds of 2 to 5 gpm (120 cc per sec to 600 cc per sec) at pressures up to 100 psi

  6. European synchrotron radiation facility at Risoe

    International Nuclear Information System (INIS)

    The results of the feasibility study on a potential European Synchrotron Radiation Facility site at Risoe, Denmark, can be summarized as follows: The site is located in a geologically stable area. The ground is fairly flat, free from vibrations and earth movements, and the foundation properties are considered generally good. The study is based upon the machine concept and main geometry as presented in the ESF feasibility study of May 1979. However, the proposed site could accomodate a larger machine (e.g. 900 m of circumference) or a multi-facility centre. The site is located in the vicinity of Risoe National Laboratory, a R and D establishment with 850 employees and a well-developed technical and scientific infrastructure, which can provide support to the ESRF during the plant construction and operation. In particular the possible combination of synchrotron radiation with the existing neutron scattering facilities in DR 3 is emphasized. The site is located 35 km west of Copenhagen with easy access to the scientific, technological and industrial organizations in the metropolitan area. The regional infrastructure ensures easy and fast communication between the ESRF and locations in the host country as well as abroad. The site is located 35 minutes drive from Copenhagen International Airport and on a main communication route out of Copenhagen. The estimated time duration for the design, construction and commissioning of ESRF phase 1 - taking into account national regulatory procedures - is consistent with that of the ESF feasibility study, i.e. approx. 6 years. The estimated captal costs associated with site-specific structures are consistent with those of the ESF feasibility study, taking into account price increase between 1979 and 1981. It should be emphasized that the study is based upon technical and scientific assessments only, and does not reflect any official position or approval from appropriate authorities. (author)

  7. Surface characterization of catalytically active metal, alloy, and compound films. Progress report, January 1, 1981-December 31, 1981

    Energy Technology Data Exchange (ETDEWEB)

    Vook, R. W.

    1981-06-01

    The work consists primarily of verification and confirmation of the Auger electron spectroscopy R-factor effect. The R-factor is a very sensitive measure of doublet Auger line shape changes or relative doublet line shifts. It can be used to identify epitaxial growth (in contrast to polycrystalline growth) and layer growth (in contrast to island or three dimensional growth). In these cases the R-factor oscillates periodically with added film thickness, for both thin and thick (approx. = 1500 A) films. The period equals the layer thickness. Since maxima in R are associated with a smooth surface and minima with a maximum in step density, R gives a measure of surface topography. An effect due to the substrate induced misfit strains on the Auger R-factor has been established. Studies were carried out on (111)Pd/(111)Cu, (111)Ag/(111)Cu, (111)Cu, and (111)Ag surfaces to establish the general validity of the results initially obtained with Pd. Experiments were begun to determine the effect of steps (as characterized by the R-factor) on the chemisorption of oxygen on Pd.

  8. Pulsed supersonic molecular beam for characterization of chemically active metal-organic complexes at surfaces

    Science.gov (United States)

    Lear, Amanda M.

    Metal-organic coordination networks (MOCNs) at surfaces consist of a complex of organic ligands bound to an atomic metal center. The MOCNs, when chosen appropriately, can form highly-ordered arrays at surfaces. Ultra-high vacuum surface studies allow control of surface composition and provide 2D growth restrictions, which lead to under-coordinated metal centers. These systems provide an opportunity to tailor the chemical function of the metal centers due to the steric restrictions imposed by the surface. Tuning the adsorption/desorption energy at a metal center and developing a cooperative environment for catalysis are the key scientific questions that motivate the construction of a molecular beam surface analysis system. Characterization of the created systems can be performed utilizing a pulsed supersonic molecular beam (PSMB) in unison with a quadrupole mass spectrometer. A PSMB allows for the highly controlled delivery of reactants with well-defined energy to a given platform making it possible to elucidate detailed chemical tuning information. In this thesis, a summary of prior theoretical molecular beam derivations is provided. Design considerations and an overview of the construction procedure for the current molecular beam apparatus, including initial characterization experiments, are presented. By impinging an Ar beam on a Ag(111) surface, the location of the specular angle (˜65°) and rough sample perimeter coordinates were determined. Additionally, surface analysis experiments, mainly Auger Electron Spectroscopy (AES), were performed to investigate the oxidation of epitaxial graphene on the SiC(0001) surface utilizing an oxygen cracking method. The AES experiments are described in detail and highlight the challenges that were faced when several different graphene samples were used for the oxygen adsorption/desorption experiments.

  9. Density-functional theory with screened van der Waals interactions applied to atomic and molecular adsorbates on close-packed and non-close-packed surfaces

    Science.gov (United States)

    Ruiz, Victor G.; Liu, Wei; Tkatchenko, Alexandre

    2016-01-01

    Modeling the adsorption of atoms and molecules on surfaces requires efficient electronic-structure methods that are able to capture both covalent and noncovalent interactions in a reliable manner. In order to tackle this problem, we have developed a method within density-functional theory (DFT) to model screened van der Waals interactions (vdW) for atoms and molecules on surfaces (the so-called DFT+vdWsurf method). The relatively high accuracy of the DFT+vdWsurf method in the calculation of both adsorption distances and energies, as well as the high degree of its reliability across a wide range of adsorbates, indicates the importance of the collective electronic effects within the extended substrate for the calculation of the vdW energy tail. We examine in detail the theoretical background of the method and assess its performance for adsorption phenomena including the physisorption of Xe on selected close-packed transition metal surfaces and 3,4,9,10-perylene-tetracarboxylic acid dianhydride (PTCDA) on Au(111). We also address the performance of DFT+vdWsurf in the case of non-close-packed surfaces by studying the adsorption of Xe on Cu(110) and the interfaces formed by the adsorption of a PTCDA monolayer on the Ag(111), Ag(100), and Ag(110) surfaces. We conclude by discussing outstanding challenges in the modeling of vdW interactions for studying atomic and molecular adsorbates on inorganic substrates.

  10. Studies of the surface structures of molecular crystals and of adsorbed molecular monolayers on the (111) crystal faces of platinum and silver by low-energy electron diffraction

    International Nuclear Information System (INIS)

    The structures of molecular crystal surfaces were investigated for the first time by the use of low-energy electron diffraction (LEED). The experimental results from a variety of molecular crystals were examined and compared as a first step towards understanding the properties of these surfaces on a microscopic level. The method of sample preparation employed, vapor deposition onto metal single-crystal substrates at low temperatures in ultrahigh vacuum, allowed concurrent study of the structures of adsorbed monolayers on metal surfaces and of the growth processes of molecular films on metal substrates. The systems investigated were ice, ammonia, naphthalene, benzene, the n-paraffins (C3 to C8), cyclohexane, trioxane, acetic acid, propionic acid, methanol, and methylamine adsorbed and condensed on both Pt(111) and Ag(111) surfaces. Electron-beam-induced damage of the molecular surfaces was observed after electron exposures of 10-4 A sec cm-2 at 20 eV. Aromatic molecular crystal samples were more resistant to damage than samples of saturated molecules. The quality and orientation of the grown molecular crystal films were influenced by substrate preparation and growth conditions. Forty ordered monolayer structures were observed. 110 figures, 22 tables, 162 references

  11. Advances and synergy of high pressure sciences at synchrotron sources

    International Nuclear Information System (INIS)

    Introductory overview to the special issue papers on high-pressure sciences and synchrotron radiation. High-pressure research in geosciences, materials science and condensed matter physics at synchrotron sources is experiencing growth and development through synergistic efforts around the world. A series of high-pressure science workshops were organized in 2008 to highlight these developments. One of these workshops, on 'Advances in high-pressure science using synchrotron X-rays', was held at the National Synchrotron Light Source (NSLS), Brookhaven National Laboratory, USA, on 4 October 2008. This workshop was organized in honour of Drs Jingzhu Hu and Quanzhong Guo in celebration of their retirement after up to 18 years of dedicated service to the high-pressure community as beamline scientists at X17 of NSLS. Following this celebration of the often unheralded role of the beamline scientist, a special issue of the Journal of Synchrotron Radiation on Advances and Synergy of High-Pressure Sciences at Synchrotron Sources was proposed, and we were pleased to invite contributions from colleagues who participated in the workshop as well as others who are making similar efforts at synchrotron sources worldwide.

  12. Electronic Structure of Germanium Nanocrystal Films Probed with Synchrotron Radiation

    Energy Technology Data Exchange (ETDEWEB)

    Bostedt, C

    2002-05-01

    The fundamental structure--property relationship of semiconductor quantum dots has been investigated. For deposited germanium nanocrystals strong quantum confinement effects have been determined with synchrotron radiation based x-ray absorption and photoemission techniques. The nanocrystals are condensed out of the gas phase with a narrow size distribution and subsequently deposited in situ onto various substrates. The particles are crystalline in the cubic phase with a structurally disordered surface shell and the resulting film morphology depends strongly on the substrate material and condition. The disordered surface region has an impact on the overall electronic structure of the particles. In a size-dependent study, the conduction and valence band edge of germanium nanocrystals have been measured for the first time and compared to the bulk crystal. The band edges move to higher energies as the particle size is decreased, consistent with quantum confinement theory. To obtain a more accurate analysis of confinement effects in the empty states, a novel analysis method utilizing an effective particle size for the x-ray absorption experiment, which allows a deconvolution of absorption edge broadening effects, has been introduced. Comparison of the present study to earlier studies on silicon reveals that germanium exhibits stronger quantum confinement effects than silicon. Below a critical particle size of 2.3 {+-} 0.7 nm, the band gap of germanium becomes larger than that of silicon--even if it is the opposite for bulk materials. This result agrees phenomenologically with effective mass and tight binding theories but contradicts the findings of recent pseudopotential calculations. The discrepancy between theory and experiments is attributed to the differences in the theoretical models and experimental systems. The experimentally observed structural disorder of the particle surface has to be included in the theoretical models.

  13. Operation of INDUS-1, India's first synchrotron radiation source

    International Nuclear Information System (INIS)

    INDUS-1 is a 450 MeV electron storage ring for the production of Synchrotron Radiation in Visible Ultra Violet (VUV) range with a critical wavelength of 61 A deg. The ring was commissioned in June 1999. Since then it is in regular operation. This Synchrotron Radiation Source (SRS) facility consists of a 20 MeV injector microtron, a 450 MeV booster synchrotron and a storage ring. In this paper operation aspects of INDUS-1 SRS facility will be presented. (author)

  14. Synchrotron radiation photoionization mass spectrometry of laser ablated species

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez Ruiz, J., E-mail: j.alvarez@iqfr.csic.e [Instituto de Quimica Fisica Rocasolano, CSIC, 28006 Madrid (Spain); Casu, A. [University of Cagliari, 09042 Monserrato (Italy); Coreno, M. [CNR-IMIP, c/o Lab. Elettra Trieste, 00016 Montelibretti (Italy); Simone, M. de [CNR-INFM, Laboratorio Nazionale TASC, 34149 Trieste (Italy); Hoyos Campo, L.M.; Juarez-Reyes, A.M. [ICF-UNAM Cuernavaca (Mexico); Kivimaeki, A. [CNR-INFM, Laboratorio Nazionale TASC, 34149 Trieste (Italy); Orlando, S. [CNR-IMIP, c/o Lab. Elettra Trieste, 00016 Montelibretti (Italy); Sanz, M. [Instituto de Quimica Fisica Rocasolano, CSIC, 28006 Madrid (Spain); Spezzani, C. [Sincrotrone Trieste, 34149 Trieste (Italy); Stankiewicz, M. [Jagiellonian University, 30-059 Krakow (Poland); Trucchi, D.M. [CNR - ISC, 00016 Montelibretti (Italy)

    2010-02-15

    The present paper describes an experimental apparatus suitable to create and study free clusters by combining laser ablation and synchrotron radiation. First tests on sulfur samples, S, showed the production, through laser ablation, of neutral S{sub n} clusters (n = 1-8). These clusters were ionized using synchrotron radiation at photon energies from 160 eV to 175 eV, across the S 2p core edge. The feasibility of such combined ablation-synchrotron radiation experiments is demonstrated, opening new possibilities on the investigation of free clusters and radicals.

  15. Synchrotron radiation photoionization mass spectrometry of laser ablated species

    International Nuclear Information System (INIS)

    The present paper describes an experimental apparatus suitable to create and study free clusters by combining laser ablation and synchrotron radiation. First tests on sulfur samples, S, showed the production, through laser ablation, of neutral Sn clusters (n = 1-8). These clusters were ionized using synchrotron radiation at photon energies from 160 eV to 175 eV, across the S 2p core edge. The feasibility of such combined ablation-synchrotron radiation experiments is demonstrated, opening new possibilities on the investigation of free clusters and radicals.

  16. Development of pulsed power modulator for induction synchrotron

    CERN Document Server

    Koseki, K

    2006-01-01

    A pulsed power modulator for the POP experiment of an induction synchrotron has been developed. Various difficulties in the development of the modulator, such as enormous power dissipation at a MOSFET, the resonant ringing in the output waveform, the isolation from the ground potential, and the incorrect action of a gate driving circuit, have been discussed and solved. The developed power modulator is installed into the existing accelerator, KEK 12GeV proton synchrotron. The POP experiment of the induction synchrotron has been successfully conducted. A single RF bunch injected from the 500 MeV booster ring was accelerated to the flat-top energy of 8 GeV.

  17. Proceedings of the workshop on LAMPF II synchrotron

    International Nuclear Information System (INIS)

    Topics covered at the workshop include: considerations for a staged approach to synchrotron construction; consideration of energy and cost for a kaon and/or antiproton factory; changing the transition energy in the main ring for the Fermilab antiproton beam; a lattice with 50% undispersed straight sections; bunch width considerations in a stretcher ring; a self-consistent longitudinal distribution; rapid-cycling tuned rf cavity for synchrotron use; considerations on a high-shunt impedance tunable RF cavity; rotating condensers; low extraction from the stretcher ring; an antiproton source for LAMPF II; synchrotron magnet circuit; power supply and ring magnet options; and notes for a kaon factory design

  18. Visualization of angiogenic vessels by synchrotron radiation microangiography

    International Nuclear Information System (INIS)

    The usefulness of synchrotron radiation microangiography for evaluating angiogenic vessels in regenerative therapy is illustrated. In a rabbit model of microvascular myocardial ischemia, angiogenic vessels in the heart were well visualized. In a rabbit model of hindlimb ischemia, vessel-regenerative therapy with fibroblast growth factor 4-gene incorporated to gelatin hydrogel well ameliorated muscle necrosis. Synchrotron radiation microangiography confirmed significant blood flow increase to adenosine administration in these treated rabbits (vascular responsiveness), but not in the control. Thus, synchrotron radiation microangiography is shown to be useful for the depiction, quantification and evaluation of angiogenic vessels in reproductive therapy. (author)

  19. 3 GeV Booster Synchrotron Conceptual Design Report

    Energy Technology Data Exchange (ETDEWEB)

    Wiedemann, Helmut

    2009-06-02

    Synchrotron light cna be produced from a relativistic particle beam circulating in a storage ring at extremely high intensity and brilliance over a large spectral region reaching from the far infrared regime to hard x-rays. The particles, either electrons or positrons, radiate as they are deflected in the fields of the storage ring bending magnets or of magnets specially optimized for the production of synchrotron light. The synchrotron light being very intense and well collimated in the forward direction has become a major tool in a large variety of research fields in physics, chemistry, material science, biology, and medicine.

  20. Combining scanning tunneling microscopy and synchrotron radiation for high-resolution imaging and spectroscopy with chemical, electronic, and magnetic contrast

    International Nuclear Information System (INIS)

    The combination of high-brilliance synchrotron radiation with scanning tunneling microscopy opens the path to high-resolution imaging with chemical, electronic, and magnetic contrast. Here, the design and experimental results of an in-situ synchrotron enhanced x-ray scanning tunneling microscope (SXSTM) system are presented. The system is designed to allow monochromatic synchrotron radiation to enter the chamber, illuminating the sample with x-ray radiation, while an insulator-coated tip (metallic tip apex open for tunneling, electron collection) is scanned over the surface. A unique feature of the SXSTM is the STM mount assembly, designed with a two free-flex pivot, providing an angular degree of freedom for the alignment of the tip and sample with respect to the incoming x-ray beam. The system designed successfully demonstrates the ability to resolve atomic-scale corrugations. In addition, experiments with synchrotron x-ray radiation validate the SXSTM system as an accurate analysis technique for the study of local magnetic and chemical properties on sample surfaces. The SXSTM system's capabilities have the potential to broaden and deepen the general understanding of surface phenomena by adding elemental contrast to the high-resolution of STM. -- Highlights: ► Synchrotron enhanced x-ray scanning tunneling microscope (SXSTM) system designed. ► Unique STM mount design allows angular DOF for tip alignment with x-ray beam. ► System demonstrates ability to resolve atomic corrugations on HOPG. ► Studies show chemical sensitivity with STM tip from photocurrent and tunneling. ► Results show system's ability to study local magnetic (XMCD) properties on Fe films.