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Your search keyword '"Lopez-Flores, V."' showing total 5 results
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5 results on '"Lopez-Flores, V."'

1. A local view of the laser induced magnetic domain dynamics in CoPd stripe domains at the picosecond time scale

Author

López-Flores, V., Mawass, M. -A., Herrero-Albillos, J., Uenal, A. A., Valencia, S., Kronast, F., and Boeglin, C.

Subjects
Physics - Applied Physics
Abstract

The dynamic of the magnetic structure in a well ordered ferromagnetic CoPd stripe domain pattern has been investigated upon excitation by femtosecond infrared laser pulses. Time-resolved X-ray magnetic circular dichroism in photoemission electron microscopy (TR-XMCD-PEEM) is used to perform real space magnetic imaging with 100 ps time resolution in order to show local transformations of the domains structures. Using the time resolution of the synchrotron radiation facility of the Helmholtz-Zentrum Berlin, we are able to image the transient magnetic domains in a repetitive pump and probe experiment. In this work, we study the reversible and irreversible transformations of the excited magnetic stripe domains as function of the laser fluence. Our results can be explained by thermal contributions, reducing the XMCD amplitude in each stripe domain below a threshold fluence of 12 mJ/cm2. Above this threshold fluence, irreversible transformations of the magnetic domains are observed. Static XMCD-PEEM images reveal the new partially ordered stripe domain structures characterized by a new local magnetic domain distribution showing an organized pattern at the micrometer scale. This new arrangement is attributed to the recovery of the magnetic anisotropy during heat dissipation under an Oersted field., Comment: 20 pages including 8 figures and 1 Table

Published
2020

3. Pump−probe experiments at the TEMPO beamline using the low-α operation mode of Synchrotron SOLEIL

Author

Nathan Beaulieu, Christine Boeglin, Bharati Tudu, Jan Lüning, Marie Agnes Tordeux, Damjan Krizmancic, Gregory Malinowski, Nicolas Jaouen, L. Stebel, Marina Tortarolo, Giuseppe Cautero, Maurizio Sacchi, Christian Chauvet, Tom Ferté, Jean Paul Ricaud, Horia Popescu, Michel Hehn, Victor Lopez-Flores, Federico Pressacco, Philippe Hollander, Cédric Baumier, Nicolas Bergeard, Mathieu G. Silly, Franck Fortuna, Renaud Delaunay, Fausto Sirotti, Debora Pierucci, R. Sergo, Silly, M. G., Ferte, T., Tordeux, M. A., Pierucci, D., Beaulieu, N., Chauvet, C., Pressacco, Flavio, Sirotti, F., Popescu, H., Lopez-Flores, V., Tortarolo, M., Sacchi, M., Jaouen, N., Hollander, P., Ricaud, J. P., Bergeard, N., Boeglin, C., Tudu, B., Delaunay, R., Luning, J., Malinowski, G., Hehn, M., Baumier, C., Fortuna, F., Krizmancic, D., Stebel, L., Sergo, R., Cautero, G., Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)-Matériaux et nanosciences d'Alsace (FMNGE), Institut de Chimie du CNRS (INC)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Réseau nanophotonique et optique, Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA), Laboratoire de photonique et de nanostructures (LPN), Laboratoire de Chimie Physique - Matière et Rayonnement (LCPMR), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université Pierre et Marie Curie - Paris 6 (UPMC), Laboratoire de physique de la matière condensée (LPMC), École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), Croissance et propriétés de systèmes hybrides en couches minces (INSP-E8), Institut des Nanosciences de Paris (INSP), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut Jean Lamour (IJL), Université de Lorraine (UL)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Centre de Sciences Nucléaires et de Sciences de la Matière (CSNSM), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Laboratorio TASC (IOM CNR), Consiglio Nazionale delle Ricerche (CNR), Elettra Sincrotrone Trieste, IMPACT N4S, ANR-15-IDEX-0004,LUE,Isite LUE(2015), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Synchrotron Soleil, ligne TEMPO, Laboratoire de Physique des Solides (LPS), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11), and Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11)

Subjects
Nuclear and High Energy Physics, Ciencias Físicas, Analytical chemistry, Synchrotron radiation, 02 engineering and technology, 01 natural sciences, 7. Clean energy, time-resolved spectroscopy, law.invention, TIME-RESOLVED SPECTROSCOPY, Optics, law, pump-probe experiments, 0103 physical sciences, 010306 general physics, Instrumentation, Radiation, Chemistry, business.industry, Synchrotron Radiation Source, Pulse duration, 021001 nanoscience & nanotechnology, Laser, Synchrotron, Astronomía, PUMP/PROBE EXPERIMENTS, Beamline, Femtosecond, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], pump-probe experiment, Time-resolved spectroscopy, 0210 nano-technology, business, CIENCIAS NATURALES Y EXACTAS
Abstract

The SOLEIL synchrotron radiation source is regularly operated in special filling modes dedicated to pump–probe experiments. Among others, the low-α mode operation is characterized by shorter pulse duration and represents the natural bridge between 50 ps synchrotron pulses and femtosecond experiments. Here, the capabilities in low-α mode of the experimental set-ups developed at the TEMPO beamline to perform pump–probe experiments with soft X-rays based on photoelectron or photon detection are presented. A 282 kHz repetition-rate femtosecond laser is synchronized with the synchrotron radiation time structure to induce fast electronic and/or magnetic excitations. Detection is performed using a two-dimensional space resolution plus time resolution detector based on microchannel plates equipped with a delay line. Results of time-resolved photoelectron spectroscopy, circular dichroism and magnetic scattering experiments are reported, and their respective advantages and limitations in the framework of high-time-resolution pump–probe experiments compared and discussed. Fil: Silly, Mathieu G.. Synchrotron Soleil; Francia Fil: Ferte, Tom. Synchrotron Soleil; Francia Fil: Tordeux, Marie Agnes. Synchrotron Soleil; Francia Fil: Pierucci, Debora. Synchrotron Soleil; Francia Fil: Beaulieu, Nathan. Synchrotron Soleil; Francia Fil: Chauvet, Christian. Synchrotron Soleil; Francia Fil: Pressacco, Federico. Synchrotron Soleil; Francia Fil: Sirotti, Fausto. Synchrotron Soleil; Francia Fil: Popescu, Horia. Synchrotron Soleil; Francia Fil: Lopez Flores, Victor. Synchrotron Soleil; Francia Fil: Tortarolo, Marina del Carmen. Synchrotron Soleil; Francia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Sacchi, Maurizio. Universite de Paris Vi. Institut des Nanosciences de Paris; Francia Fil: Jaouen, Nicolas. Synchrotron Soleil; Francia Fil: Hollander, Philippe. Synchrotron Soleil; Francia Fil: Ricaud, Jean Paul. Synchrotron Soleil; Francia Fil: Bergeard, Nicolas. Synchrotron Soleil; Francia Fil: Boeglin, Christine. Synchrotron Soleil; Francia Fil: Tudu, Bharati. Synchrotron Soleil; Francia Fil: Delaunay, Renaud. Universite de Paris VI; Francia Fil: Luning, Jan. Universite de Paris VI; Francia Fil: Malinowski, Gregory. Synchrotron Soleil; Francia Fil: Hehn, Michel. Synchrotron Soleil; Francia Fil: Baumier, Cedric. Université Paris Sud; Francia Fil: Fortuna, Franck. Université Paris Sud; Francia Fil: Krizmancic, Damjan. Elettra - Synchrotron Light Laboratory; Italia Fil: Stebel, Luigi. Elettra - Synchrotron Light Laboratory; Italia Fil: Sergo, Rudi. Elettra - Synchrotron Light Laboratory; Italia Fil: Cautero, Giuseppe. Elettra - Synchrotron Light Laboratory; Italia

Published
2017
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4. Au and Pt Remain Unoxidized on a CeO 2 -Based Catalyst during the Water-Gas Shift Reaction.

Author

Reina TR, Gonzalez-Castaño M, Lopez-Flores V, Martínez T LM, Zitolo A, Ivanova S, Xu W, Centeno MA, Rodriguez JA, and Odriozola JA

Abstract

The active forms of Au and Pt in CeO 2 -based catalysts for the water-gas shift (WGS) reaction are an issue that remains unclear, although it has been widely studied. On one hand, ionic species might be responsible for weakening the Ce-O bonds, thus increasing the oxygen mobility and WGS activity. On the other hand, the close contact of Au or Pt atoms with CeO 2 oxygen vacancies at the metal-CeO 2 interface might provide the active sites for an efficient reaction. In this work, using in situ X-ray absorption spectroscopy, we demonstrate that both Au and Pt remain unoxidized during the reaction. Remarkable differences involving the dynamics established by both species under WGS atmospheres were recognized. For the prereduced Pt catalyst, the increase of the conversion coincided with a restructuration of the Pt atoms into cuboctahedrical metallic particles without significant variations on the overall particle size. Contrary to the relatively static behavior of Pt 0 , Au 0 nanoparticles exhibited a sequence of particle splitting and agglomeration while maintaining a zero oxidation state despite not being located in a metallic environment during the process. High WGS activity was obtained when Au atoms were surrounded by oxygen. The fact that Au preserves its unoxidized state indicates that the chemical interaction between Au and oxygen must be necessarily electrostatic and that such an electrostatic interaction is fundamental for a top performance in the WGS process.

Published
2022
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5. Pump-probe experiments at the TEMPO beamline using the low-α operation mode of Synchrotron SOLEIL.

Author

Silly MG, Ferté T, Tordeux MA, Pierucci D, Beaulieu N, Chauvet C, Pressacco F, Sirotti F, Popescu H, Lopez-Flores V, Tortarolo M, Sacchi M, Jaouen N, Hollander P, Ricaud JP, Bergeard N, Boeglin C, Tudu B, Delaunay R, Luning J, Malinowski G, Hehn M, Baumier C, Fortuna F, Krizmancic D, Stebel L, Sergo R, and Cautero G

Abstract

The SOLEIL synchrotron radiation source is regularly operated in special filling modes dedicated to pump-probe experiments. Among others, the low-α mode operation is characterized by shorter pulse duration and represents the natural bridge between 50 ps synchrotron pulses and femtosecond experiments. Here, the capabilities in low-α mode of the experimental set-ups developed at the TEMPO beamline to perform pump-probe experiments with soft X-rays based on photoelectron or photon detection are presented. A 282 kHz repetition-rate femtosecond laser is synchronized with the synchrotron radiation time structure to induce fast electronic and/or magnetic excitations. Detection is performed using a two-dimensional space resolution plus time resolution detector based on microchannel plates equipped with a delay line. Results of time-resolved photoelectron spectroscopy, circular dichroism and magnetic scattering experiments are reported, and their respective advantages and limitations in the framework of high-time-resolution pump-probe experiments compared and discussed.

Published
2017
Full Text
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