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17 results on '"Gregoratti, L."'

3. Solid-to-solid phase transition from amorphous carbon to graphite nanocrystal induced by intense femtosecond x-ray pulses

Author

Gaudin, J., Chalupský, J., Toufarová, M., Vyšín, L., Hájková, V., Sobierajski, R., Burian, T., Dastjani-Farahani, Sh., Graf, A., Amati, M., Gregoratti, L., Hau-Riege, S. P., Hoffmann, G., Juha, L., Krzywinski, J., London, R. A., Moeller, S., Sinn, H., Schorb, S., Störmer, M., Tschentscher, Th., Vorlíček, V., Vu, H., Bozek, J., and Bostedt, C.

Subjects
Condensed Matter - Materials Science, Condensed Matter - Mesoscale and Nanoscale Physics, Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Physics::Atomic and Molecular Clusters, Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences
Abstract

We present the results of an experiment where amorphous carbon was irradiated by femtosecond x-ray free electron laser pulses. The 830 eV laser pulses induce a phase transition in the material which is characterized ex-situ. The phase transition energy threshold is determined by measuring the surface of each irradiated area using an optical Nomarski microscope. The threshold fluence is found to be 282 +/- 11 mJ/cm^2, corresponding to an absorbed dose at the surface of 131 +/-5 meV/atom. Atomic force microscopy measurements show volume expansion of the irradiated sample area, suggesting a solid to solid phase transition. Deeper insight into the phase transition is gained by using scanning photoelectron microscopy and micro-Raman spectroscopy. Photoelectron microscopy shows graphitization, i.e. modification from sp3 to sp2 hybridization, of the irradiated material. The micro-Raman spectra show the appearance of local order, i.e. formation of graphite nanocrystals. Finally, the nature of the phase transition is discussed, taking into account previous theory and experimental results.

Published
2011
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8. Electron microscopy and photoelectron spectromicroscopy study of catalyst-free transformation of carbon nanoparticles into nanotubes

Author

Botti S., Ciardi R., Fabbri F., Larciprete R., Goldoni A., Gregoratti L., Kaulich B., and Kiskinova M.

Abstract

The reorganization of the morphologically complex amorphous carbon nanoparticle layers deposited on a Si substrate into ordered sp2 entities was investigated by means of two complementary techniques, synchrotron radiation x-ray photoelectron microscopy and scanning electron microscopy, which provided the necessary chemical and structural information at submicrometer length scales. The studies were focused on the effect of the local thickness of the carbon nanoparticle layer on the extent of the restructuring process. The lateral distribution of the phases formed on the surface and their local chemical configuration were revealed by measuring C 1s and the Si 2p core level spectra with photoelectron spectromicroscopy. The results showed that an effective graphitization, which on the basis of complementary characterization techniques was associated to the formation of single-wall nanotubes, occurs only in areas with a high density of nanoparticles. These findings indicate that tube self-assembling is promoted by the interaction between neighboring nanoparticles.

Published
2005

9. Direct writing of fluorescent patterns on lif films by x-ray microprobe

Author

Larciprete R., Gregoratti L., Danailov M., Montereali R. M., Bonfigli F., and Kiskinova M.

Abstract

Fluorescent patterns with submicron dimensions have been obtained by creating stable F-3(+) and F-2 color centers in LiF films using a focused x-ray beam provided at the ELETTRA synchrotron radiation facility. The patterns were written by scanning the LiF specimen with respect to the x- ray microprobe. In these attempts, using an x-ray microspot with a diameter of 100 nm and a flux density greater than or equal to10(9) photons/s, we generated similar to500-nm-wide lines efficiently emitting in the visible spectral region when excited by blue light at 458 nm. Preliminary results indicate that the spectral distribution of the emitted luminescence can be changed by varying the photon dose delivered to the sample.

Published
2002

10. COLLABORATIVE OVERVIEW OF RANDOMIZED TRIALS OF ANTIPLATELET THERAPY .1. PREVENTION OF DEATH, MYOCARDIAL-INFARCTION, AND STROKE BY PROLONGED ANTIPLATELET THERAPY IN VARIOUS CATEGORIES OF PATIENTS

Author

ALTMAN, R, CARRERAS, L, DIAZ, R, FIGUEROA, E, PAOLASSO, E, PARODI, J, CADE, J, DONNAN, G, EADIE, M, GAVAGHAN, T, OSULLIVAN, E, PARKIN, D, RENNY, J, SILAGY, C, VINAZZER, H, ZEKERT, F, ADRIAENSEN, H, BERTRANDHARDY, J, BRAN, M, DAVID, J, DRICOT, J, LAVENNEPARDONGE, E, LIMET, R, LOWENTHAL, A, MORIAU, M, SCHAPIRA, S, SMETS, P, SYMOENS, J, VERHAEGHE, R, VERSTRAETE, M, ATALLAH, A, BARNETT, H, BATISTA, R, BLAKELY, J, CAIRNS, J, COTE, R, CROUCH, J, EVANS, G, FINDLAY, J, GENT, M, LANGLOIS, Y, LECLERC, J, NORRIS, J, PINEO, G, POWERS, P, ROBERTS, R, SCHWARTZ, L, SICURELLA, J, TAYLOR, W, THEROUX, P, TURPIE, A, WEISEL, R, CUI, J, LIU, L, PIRK, J, BAY, C, BOYSEN, G, KNUDSEN, J, PETERSEN, P, SORENSEN, P, TONNESEN, H, HARJOLA, P, ARCAN, J, BALKAU, B, BLANCHARD, J, BOISSEL, J, BONEU, B, BOUSSER, M, BROCHIER, M, CLOAREC, M, CRIBIER, G, DECHAVANNE, M, DROUIN, P, ESCHWEGE, E, GUIRAUDCHAUMEIL, B, HUGONOT, R, LEIZOROVICZ, A, LORIA, Y, MICHAT, L, MIROUZE, J, PANAK, E, PASTEYER, J, RASCOL, A, REVOL, L, ROY, M, SELLES, J, SLAMA, G, STARKMAN, C, TEULE, M, THIBULT, N, VERRY, M, ALBERT, F, ANDRASSY, K, BREDDIN, K, ECKEL, R, ENCKE, A, FROHLICH, J, HARTUNG, B, HEISS, H, HESS, H, HOFLING, B, KRAUSE, D, LATTA, G, LINKE, H, LOEW, D, LORENZ, R, MIDDLETON, K, NOVAK, G, OLDENDORF, M, PFLUGER, N, RAITHEL, D, REUTER, R, SCHETTLER, G, SCHNITKER, J, SCHOOP, W, STIEGLER, H, UBERLA, K, VOGEL, G, WEBER, M, WELBERS, I, ZEITLER, E, ARAPAKIS, G, CHAN, T, MOK, C, SZABO, R, MISRA, N, REDDY, K, FITZGERALD, G, APOLLONIO, A, BALSANO, F, BASELLINI, A, CANDELISE, L, CATALANO, M, CIAVARELLA, N, CIUFFETTI, G, COCCHERI, S, CORTELLARO, M, CORVI, G, COTO, V, DAVI, G, DECATERINA, R, DIPERRI, T, FIESCHI, C, GENTILE, R, GREGORATTI, L, GRESELE, P, LAVEZZARI, M, LIBRETTI, A, MAGNANI, B, NENCI, G, PAGANO, G, PATRONO, C, PEDRINI, L, PINI, M, PRANDONI, P, ROMEO, F, ROVELLI, F, RUDELLI, G, RUVOLO, G, SIGNORINI, G, TOGNONI, G, VIOLI, F, FUJIMORI, T, KAGEYAMA, M, KATSUMURA, T, KITAMURA, S, MAEDA, K, SUZUKI, A, TOHGI, H, UCHIYAMA, S, UTSUMI, H, GARCIA, A, ALGRA, A, DENOTTOLANDER, G, KUPPER, A, VANGIJN, J, HART, H, KAPPELLE, L, KOUDSTAAL, P, LEMMENS, T, LODDER, J, PANNEBAKKER, M, SERRUYS, P, VANDENBELT, A, VANDERMEER, J, VANDERVIJGH, A, VERHEUGT, F, VETH, G, DALE, J, JOHANNESSEN, K, THAULOW, E, POPESCU, P, TIBERIU, N, AZNAR, J, ESMATJES, E, GUITERAS, P, LASIERRA, J, LOPEZTRIGO, P, ORIOL, A, POMAR, L, ROCHA, E, SANCHEZ, F, SANCHORIEGER, J, SANZ, G, BERGLUND, U, BLOMSTRAND, C, BOBERG, M, BRITTON, M, ELWIN, C, HELMERS, C, HOLM, J, JANZON, L, JUULMOLLER, S, MULEC, H, OLSSON, J, PERSSON, S, RASMANIS, G, ROSEN, A, SAMUELSSON, K, SOREFF, J, WAHLGREN, N, WALLENTIN, L, BAUR, H, BOKSLAG, M, BOLLINGER, A, MEIER, B, PFISTERER, M, SITTHIAMORN, C, ACHESON, E, APPLEBY, P, ASSCHER, A, AUKLAND, A, BAIGENT, C, BALA, S, BARNETT, A, BELL, P, BEWS, S, BORN, G, BRANAGAN, J, BROOKS, N, BROWN, M, BROWSE, N, CAPILDEO, R, CARMALT, M, CARTER, A, CHALMERS, I, CLARKE, M, CLARKE, R, CLYNE, C, COLLINS, R, COOKE, E, COUTTS, G, COVE, D, CROWTHER, P, CUTHBERTSON, W, DEBONO, D, DICKERSON, C, DICKINSON, J, DOLL, R, DORMANDY, J, DUNBABIN, D, ELL, S, ELPHINSTONE, P, ELWOOD, P, ENGLISHBY, V, FARRELL, B, FISKERSTRAND, C, FLATHER, M, FOLEY, T, FOULDS, T, FOX, K, FRANKS, P, FRASER, H, GARDECKI, T, GAWEL, M, GENT, A, GERSHLICK, A, GODWIN, J, GOLDMAN, M, GRAY, C, GRAY, D, GRAY, R, HANDOLL, H, HANKEY, G, HARRISON, M, HENDERSON, N, HEPTINSTALL, S, HOBBIGER, S, JONES, E, JONES, N, JOST, S, JULIAN, D, KELLETT, J, KESTER, R, LOWE, G, MACKENZIE, J, MCCOLLUM, C, MEAD, G, MEADE, T, MENDELOW, D, MILLER, J, MORRIS, G, NICHOL, C, NOBLE, M, OBRIEN, J, OGIER, M, PARISH, S, PARRY, M, PETO, R, POWELL, J, POZZILLI, P, QIZILBASH, N, RAHMAN, A, RAJAH, S, RICHARDS, D, RICHARDS, S, RIPLEY, R, ROBERTS, V, ROSE, F, RUSSELL, R, RUBIN, P, RUCKLEY, C, SANDERCOCK, P, SHAW, M, SHAW, K, SHELLEY, J, SLATTERY, J, SLEIGHT, P, SMITH, S, STEWARTLONG, P, SWEETNAM, P, TANSEY, M, TINDALL, H, TURNEY, J, TYLER, H, VAREY, N, VESSEY, M, WALKER, M, WARLOW, C, WILCOX, R, WILLEMS, H, WOOD, E, WYNJONES, E, ADAMS, H, BARTON, B, BEDFORD, R, BICK, B, BINGHAM, S, BROWN, B, BRYANT, T, BURING, J, CABOT, C, CANNER, P, CHESEBRO, J, CHRISMAN, O, CLAGETT, G, COLWELL, J, DYKEN, M, ELLIS, D, FIELDS, W, FURBERG, C, FUSTER, V, GOLDMAN, S, GRANETT, J, GREEN, R, GREEN, D, HARDY, R, HARKER, L, HARRIS, W, HART, R, HASS, W, HENNEKENS, C, HILL, D, HUME, M, IGLOE, M, JOHNSON, G, JONAS, S, KNATTERUD, G, KOHLER, T, LEMBO, N, LEWIS, D, LOCKHART, E, MAJERUS, P, MCENANY, M, MCKENNA, R, MEHTA, J, MEYER, J, MOLONY, B, MORITZ, T, NICOLOFF, D, NYCZ, G, ONO, H, PANTELY, G, PHILLIPS, S, RIDKER, P, ROBERTSON, J, ROTHBART, R, SALZMAN, E, SAUTTER, R, SCHLANT, R, SCHOENBERGER, J, SENGEKONTACKET, M, SHARMA, G, STEELE, P, STEINNAGEL, K, STRATTON, J, SULLIVAN, J, TIMMIS, G, TOOLE, J, WEISMAN, S, WHITE, C, WIRECKI, M, WOMBOLT, D, WONG, R, YUSUF, S, ZADINA, K, and ZUCKER, D

Published
1994

12. Large gecko mimetic tapes as new joining technology

Author

Gregoratti, L., Andrea GOLDONI, Trygub, O., Marazzi, M., Tormen, M., Grenci, G., Dalzilio, S., Vidoni, R., and Gasparetto, A.

Subjects
Adhesive properties, Hierarchical structures, Mechanical gripping, Surface compatibility, Environmental resistance, Large scale productions, Metallic substrate, Vertically aligned

14. Band discontinuity fluctuations and local chemistry at the GaSe-Si interface

Author

Zacchigna, M., Sirigu, L., Almeida, J., Berger, H., Gregoratti, L., Marsi, M., Kiskinova, M., and Margaritondo, G.

Subjects
ELETTRA, INHOMOGENEITIES, GE, METAL, HETEROJUNCTION
Abstract

Photoemission spectromicroscopy data on Si-GaSe with 0.2 mu m lateral resolution revealed laterally inhomogeneous interface Se-Si chemical reactions. The local Si 2p fits agrees with interface Si selenide parameters; the Se 3d peaks indicate a Si-selenide component; the Ga 3d peaks exhibit a metallic component whose intensity increases with Si coverage. This local interface reaction is related to lateral changes in the band lineup. (C) 1998 American Institute of Physics. [S0003-6951(98)02839-3].

16. Characterization of catalytic materials with scanning photoelectron microscopy: Present and future

Author

Benedetto Bozzini, Belén Alemán, Maya Kiskinova, Matteo Amati, Luca Gregoratti, Hikmet Sezen, Amati, Matteo, Aleman, Belen, Bozzini, Benedetto, Gregoratti, L., Sezen, H., and Kiskinova, M.

Subjects
Chemical imaging, Chemistry, Nanotechnology, 02 engineering and technology, Surfaces and Interfaces, 010402 general chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Polypyrrole, Electrocatalyst, 01 natural sciences, Synchrotron, Scanning photoelectron microscopy, 0104 chemical sciences, Surfaces, Coatings and Films, Catalysis, Characterization (materials science), law.invention, chemistry.chemical_compound, Chemical state, law, Materials Chemistry, 0210 nano-technology
Abstract

Synchrotron-based scanning photoelectron microscopy has opened unique opportunities for exploiting processes occurring at surfaces and interfaces, which control the properties of functional materials where issues of complexity at microscopic length scales should be faced and understood. The present article aims at demonstrating the present capabilities of this microscopic method to explore the surface composition of micro- and nano-structured materials, focused on cases relevant to catalysis. We report and discuss some recent results about the chemical state of supported PtRh alloy microparticles under oxidation conditions and the changes in the status of a Co/polypyrrole electrocatalyst due to ageing in the course of the oxygen reduction reaction. Monitoring the lateral inhomogeneity in the chemical state at sub-micrometer length scales by combining chemical imaging and micro-spectroscopy has provided comprehension of events occurring at the catalyst surface, which determine the performance of the morphologically complex catalytic systems. Ongoing efforts for development and implementing of new set-ups that allow working closer to the realistic conditions of catalytic reactions are also outlined and briefly discussed.

Published
2016

17. Carbothermal Transformation of TiO2 into TiOxCy in UHV: Tracking Intrinsic Chemical Stabilities

Author

Carlos Valero-Vidal, Diego Fittipaldi, Nathalie Bozzolo, Julia Kunze-Liebhäuser, Gianfranco Pacchioni, Suzanne Jacomet, Gaetano Granozzi, Luca Gregoratti, Laura Calvillo, Andrea Vittadini, Celine Rüdiger, Stefano Agnoli, Cristiana Di Valentin, Marco Favaro, Department of Chemical Sciences, Universita degli Studi di Padova, Dipartimento di Scienza dei Materiali = Department of Materials Science [Milano-Bicocca], Università degli Studi di Milano-Bicocca [Milano] (UNIMIB), Department of Physics E19 [Garching], Technische Universität Munchen - Université Technique de Munich [Munich, Allemagne] (TUM), Institute of Physical Chemistry, University of Innsbruck, Dipartimento di Scienze Chimiche, Centre de Mise en Forme des Matériaux (CEMEF), MINES ParisTech - École nationale supérieure des mines de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Elettra Sincrotrone Trieste, Calvillo, L, Fittipaldi, D, Rüdiger, C, Agnoli, S, Favaro, M, Valero Vidal, C, DI VALENTIN, C, Vittadini, A, Bozzolo, N, Jacomet, S, Gregoratti, L, Kunze Liebhäuser, J, Pacchioni, G, and Granozzi, G

Subjects
Suboxide, nitrides, oxidation, Photoemission spectroscopy, 4TiO, Surfaces, Coatings and Film, chemistry.chemical_element, Nanotechnology, Nitride, Electrocatalyst, electrocatalysts, TRANSITION-METAL CARBIDES, [SPI.MAT]Engineering Sciences [physics]/Materials, Phase (matter), titanium, Physical and Theoretical Chemistry, methanol, ELECTROCATALYSTS, SUPPORT MATERIALS, Electronic, Optical and Magnetic Material, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, Energy (all), General Energy, chemistry, Chemical physics, FUEL-CELL APPLICATIONS, nanoparticles, Density functional theory, Crystallite, Carbon
Abstract

International audience; The conversion of anodic TiO2 films into TiOxCy in ultrahigh-vacuum (UHV) has been traced by photoemission spectroscopy in order to optimize the process parameters and study the different phase stabilities. In addition, density functional theory (DFT) calculations have been performed in order to elucidate the main questions about TiOxCy composition and stability. The experimental data indicate that the anodic TiO2 film is stable both in UHV and ethylene background up to ca. 600 K, and at this temperature, it starts to reduce leading to suboxide TiOx species. Above ca. 750 K, the formation of TiOxCy starts, since the oxygen vacancies begin to be replaced by carbon atoms. A surface enrichment in TiO2 and elemental carbon has been detected on the converted TiOxCy film at room temperature. Real-time measurements have shown that this phenomenon takes place during the cool down process and DFT calculations suggest a possible explanation: as the temperature decreases below ca. 750 K (temperature at which the formation of TiOxCy starts), the TiOxCy phase is not thermodynamically stable, and it decomposes into TiO2 and elemental carbon. The comparison of the experimental valence band data with DFT results has also allowed to establish that the film surface is not homogeneous and that segregation of TiO and TiC systems may take place. On the other hand, the local compositional study carried out by scanning photoelectron microscopy has shown that the conversion of the film is not homogeneous but depends on the grain orientation, in particular crystallites with an orientation close to 0> and 0> planes show a higher grade of conversion. Both experimental and DFT data validate the use of TiOxCy as an innovative support for electrocatalysis.

Published
2014

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