Rayonnement synchrotron
Rayonnement synchrotron

Photographie aérienne de l'ESRF (Grenoble) (Crédit Photo : © Denis Morel / ESRF)

Aujourd'hui, les anneaux synchrotrons, tels que l'ESRF à Grenoble ou le synchrotron SOLEIL sur le plateau de Saclay, sont des sources intenses de photons (de l'infra-rouge aux rayons X). De nombreuses équipes de l'IRAMIS réalisent régulièrement des expériences autour de ces sources.

#123 - Màj : 22/04/2010
Technique (desc. gen.)
N. Barrett1 and O. Renault2
1  CEA DSM/IRAMIS/SPCSI, CEA Saclay, 91191 Gif-sur-Yvette, France 2  CEA-LETI, MINATEC, 17 rue des Martyrs, 38054 Grenoble Cedex 9, France Le rayonnement synchrotron apporte plusieurs dimensions nouvelles aux spectroscopies des photoélectrons.
Voir aussi
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Les effets ioniques dits spécifiques regroupent tous les effets certes d'origine électrostatique mais qui ne peuvent être expliqués par la seule valence des ions.
N.T. Barrett ; V.N. Strocov (SLS, Switzerland) ; E.E. Krasovskii (Univ. Kiel, Germany) ; W. Schattke (Univ. San Sebastian, Spain) ; H. Berger (EPFL, Switzerland), D. Schrupp (Univ. Augsburg, Germany) ; R. Claessen (Univ. Würzburg, Germany) ; J.-M. Themlin
In photoemission, the initial-state k⊥ can be deduced if the final-state surface-perpendicular dispersion E(k⊥) into the crystal bulk is known. The widely used free-electron-like (FE-like) model fails for many quasi 2D systems.[1] Final states can feature dramatic non-free-electron effects, [2] and can undergo significant energy shifts due to band- and k-dependent excited-state self-energy corrections ΔΣ.
H. Bureau, C. Gondé, B. Ménez, M. Semet
Melt and fluid inclusions in olivines from the last 197 days long eruption of Piton de la Fournaise (Réunion Island) that began March 9, 1998, have recorded a range of volatile partial pressures. The highest pressures (400-540 MPa) so far for this volcano are found in unusually Fo-rich olivines from a vent remote from the main eruptive activity.
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K-edge X-ray absorption and 2p-XPS spectra of 3d-element oxides present spectral features which cannot be explained within a simple one-electron model. These features reveal the fine electronic structure of transition metal (TM) oxides valence states resulting from hybridized TM-3d and O-2p states, and the correlations between these valence electrons.
H Bureau, D. Massare
Micro-experimental studies require the use of diamond anvil cells, allowing observation and in situ characterization of the studied phase equilibrium using classical spectroscopy techniques (Infrared, Raman, X-Ray Fluorescence, X-Ray diffraction…). In the Bassett’s cell, the sample is contained in a rhenium gasket compressed by two type I diamonds of 0.21 carat with 1 mm flats. The initial diameter of the borehole in the gasket is 0.5 mm.
H. Bureau, B. Ménez, V. Malavergne, A. Somogyi, M. Munoz, A. Simionovici, D. Massare, M. Burchard, S. Kubsky, C. Shaw
Subduction zones are the locations where the oceanic crust, which experienced intense interaction with seawater, is buried back into the Earth’s mantle. These environments play a critical role in the global geochemical cycle of Earth, being the location at which chemical components are both recycled into the mantle and returned to the atmosphere through volcanism.
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Synchrotron based micro X-ray Absorption Spectroscopy was used to obtain micro scale chemical information such as coordination and oxidation state of phases constituting corrosion products within archaeological iron artefacts buried in soil. The knowledge about iron corrosion process related to the presence of chlorine, is particularly important for restoration and conservation of the metallic artefacts.
N.T. Barrett, L.F. Zagonel, V. Fouquet, M. Gautier-Soyer ; Coll. M. Bäurer, M. Hoffmann (Univ. Karlsruhe, Germany)
This research is carried within the framework of the 6th PCRD INCEMS project. [1] The objective is to predict the properties of multifunctional ceramics in the presence of Intergranular films (IGFs). Regrouping expert theoretical and experimental groups from Germany, UK, Slovenia and France, the CEA contributes the possibility of spectroscopic imaging on the mesoscopic scale, providing essential experimental verification of the extension of atomistic models to larger scales.
N.T. Barrett, L. Zagonel, S. Palacin, J. Charlier ; Coll. O. Renault, A. Bailly, R. Brochier, A. Chabli (CEA/LETIMinatec) N. Brookes, J. Cezar (ESRF) ; K. Winkler, B. Kromeker, D. Funneman (Omicron) ; S. Poissonet (CEA/SRMP)
Photoelectron emission microscopy combined with intense photon sources is becoming a powerful analytical tool with both spatial resolution down to a few nanometers and spectroscopic capabilities. One can laterally resolve surface domains according to their magnetization, chemical composition, electronic structure, and even follow the dynamics of domain movement, catalysis or laser emissions using time resolved detection systems.
Prediction of long term corrosion (on several hundred years) of low alloy steels is a crucial issue in several research domains: metallic cultural heritage conservation, civil engeeniring, etc. Recent results demonstrate that, despite the corrosion layers could reach several millimetre thicknesses, the kinetics can be controlled at the nanoscale (presence of barrier layer at the metal/oxide interface, influence of crystallinity in the electrochemical reactivity, etc).
Jun Han (PhD), Sergio Gomez (PhD, University of Vigo), Zeliha Cansu Canbek (running PhD), Fabien Hubert (PhD 2009), Benjamin Abécassis (PhD 2006), Fabienne Testard, Olivier Spalla
General objectives  We aim at understanding the microscopic mechanisms controlling the formation of nanoparticles. Different types of NPs are studied in the LIONS and among them gold NPs have already been the subject of several achieved PhD (B. Abécassis and F. Hubert) and on-going in-house studies (J. Han) and collaborative ones (S. Gomez from the Univiersity og Vigo).
Faits marquants scientifiques
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Avec l'avènement de l'électronique de spin (spintronique), il est devenu particulièrement important de visualiser et de comprendre la manière dont se forment les domaines magnétiques dans les structures magnétiques. Ceci est plus particulièrement délicat pour les couches antiferromagnétiques, qui ne présentent aucune aimantation macroscopique et n'interagissent par conséquent que faiblement avec des sondes.
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D. Sen, O. Spalla, O. Taché, P. Haltebourg, A. Thill
ESRF Highlights 2007 The synthesis of ordered, homogeneous porous grains is an expanding area of materials research. One strategy for their formation is to dry the spray of a complex mixture containing nanoparticles and templating agents [1]. In this process, a continuous flow of micrometric droplets, made from the initial dilute solution, is dried along a hot tube in order to evaporate the solvent. Self-organisation of the constituents takes place during the evaporation.
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V. Padmanabhan, J. Daillant, L. Belloni, S. Mora, M. Alba, and O. Konovalov
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