Abstract Book

PROGRAM AND
ABSTRACT BOOK
June 6-7, 2002
Amphithéâtre P. Lehmann
Orsay – FRANCE
Foreword
It is a great pleasure for us to introduce this users' meeting. We first want to thank
the members of the users' committee for their work in preparing such an exciting
program, and C. Jucha, C. Martelle, M. Le Monze and D. Michalowicz for their
help in the organisation. We are happy that so many of our users will attend the
meeting and present their work here.
Last year has been marked by several important events, some of them happy,
some other sad. You probably know that the death of Pierre Marin occurred
abruptly last April, and that his disappearing was a shock for the laboratory.
Pierre was tightly associated with the life of LURE, and he was one of the most
active in the fight for SOLEIL.
This last year, has also seen an acceleration of the participation of the LURE's staff
to SOLEIL (around 100 persons working partially or full time), mainly for the
machine and infrastructures, but also in the beam lines projects. LURE scientists
are being actively involved in almost all beam line projects for SOLEIL.
Concerning the functioning of the machines a small reduction of the available
beam-time has been judged necessary in order to facilitate the participation of
LURE's staff to SOLEIL. This reduction has been limited for the users, by nearly
suppressing almost all machine dedicated shifts.
As decided by LURE's council, the shutdown of DCI and SuperACO has been
fixed at the end of December, 2003. An important point which will be discussed in
the "open discussion" will be the ways of accessing to other facilities during the
2004-2006 period.
Finally, several new experimental developments have been made accessible to
users. Most of them are already operating at LURE. Many will be temporarily
transfered in other facilities during the period 2004-2006 and will help maintaining
the scientific activity of our community in Synchrotron Radiation.
Abderrahmane Tadjeddine, Elisabeth Dartyge, Jean Daillant
Hommage de la Direction du LURE
à Pierre MARIN
lors de l’ouverture du Colloque Utilisateurs
2002
Tribute of LURE and its USERS to the outstanding
contribution of
Pierre MARIN
1927-15th April 2002
1971: Preliminary contacts with potential users of the
Synchrotron Radiation.
1973: Construction of the A8. Beam Line.
1975: Starting up of DCI. Equipped with the D1 Beam Line,
soon followed by the D2 BL.
1976-1988: ACO as Synchrotron radiation facilities.
1979: Participation of members of the Ring Service of LURE
to preliminary studies of ESRF leading to the so-called
“Super ACO mesh”.
1980: Proposal for a low emittence VUV ring Super ACO.
1982-1986: Construction of S.ACO.
1987: Installation and starting-up of the first beam lines (BM
and insertions).
1988: Shut-down of the 'ACO ring.
1987-1992: Participation to the Machine Advisory Council of
the ESRF.
1992-1994: Collaboration to the conception and the design of
the vacuum chamber of ESRF.
1992-2000: Active multifaceted defence of SOLEIL.
Strong Commitment in the creation of Science ACO for the
spreading of the scientific culture and education.
Active support of the SESAME project.
New developments in synchrotron instrumentation
During the two last years important experimental developments have been made, with a special
financial support from the CNRS for one part (option1) or in the frame of specific actions of the
laboratory for the other part.
1) Option I
The CNRS has allocated to LURE a budget for the "Option I" program, in order to upgrade a
certain number of installations and make them transferable to SOLEIL.
a) Some projects are "heavy projects" and will be directly implanted in a 3th generation source:
XPEEM at ELETTRA. (responsible R. Belkhou, M. De Santis Y. Vogel). This project is
a collaboration with the Louis Néel Laboratory and the Laboratory of Crystallography of
Grenoble and will perform spectro-microscopic studies of surfaces as well as imaging of
magnetic domains.
Microfocus at SLS (A.-M. Flank). Micro XAS in the soft X-ray range will amplify the
performances of this technique which is a specificity of LURE.
A discussion about the access to these lines should be hold in the open session.
An other project concerns the developing of a new kind of two-dimensional camera for
protein crystallography, with unequaled performances. This camera will be tested at LURE and
then at the ESRF (R. Fourme).
The SFG setup of CLIO will be completely renewed and transferred in a new
experimental room. The old YAG laser will be replaced by a cw YLF laser and several OPObased table lasers synchronized with the CLIO Free Electron Laser optimized in the high energy
spectral range (Near IR and visible) will allow LURE to provide a unique laser facility up to
90µm.
The other projects are various operations on beam lines of LURE, they will be operative at the
end of the year and opened to the users for the next program committee:
In the domain of low energies (5-40 eV) the atoms and molecules community will have
several ameliorations of the available experiments: realization of a reflectron spectrometer,
acquisition of new sources of radicals (SAPHIRS and CERISES experiments, the project leaders
are M. Elhanine and Ch. Alcaraz on the lines SU5 and SA63), and also the developing of a
spectrometer for the VUV dichroism by L. Nahon on SU5.
Two inelastic scattering experiments in the soft X-ray range are developed: one is for
magnetic resonant scattering of polarized X-rays (M. Sacchi, on SU7 and SB7), the other one
analyses in energy the inelastically scattered photons near an absorption edge (C. Hague); these
two experiments are designed to study surfaces in ultra high vacuum, and are mobile so they are
installed in Lure and also move to other synchrotron sources.
The experiment "high resolution in photoemission" is equipped with a SCIENTA detector
of improved resolution (A. Taleb, SU3)
The MBE coupled with SU22 or SU23 and who was principally dedicated to surface
magnetism experiments, has been implemented with a oxygen plasma source, allowing to make
spectroscopy measurements on oxides (F. Fortuna).
In the hard X-ray range, the surface scattering line has been upgraded (Y. Garreau,
DW12), and on the EXAFS beam-lines the priority has been to develop the possibility of
environment of the samples: cryostats allowing any kind of detection, DSC…( A. Traverse, D42,
S. Belin and V. Briois, D44)
Concerning the high pressure experiments which are well developed in LURE for
scattering as well as for absorption measurements, new cells allowing to extend the domain of
energy to the low limits of 5 keV have been realized and successfully tested. This concerns the
D11 line (F. Baudelet and Ch. Giorgetti), and J.-P. Itié, and is a collaboration between LURE
and PMC at Jussieu.
2 Specific operations
A cryostat allowing to perform magnetic dichroism in the soft X-rays at 100 mK and under 6 T
has been constructed by a collaboration between LURE, the LMCP in Jussieu and the IPCMS in
Strasbourg (P. Sainctavit, J.-P. Kappler). This cryostat will be part time in LURE (on SU22 and
SU23), part time in ELETTRA and at the ESRF.
The DW31 beam line is being equipped with diffraction set-up designed to support a CCD
camera detector. This 2D detection allows not only recording a limited number of Bragg peaks,
but also the exploration of the complete reciprocal space. This equipment-developed by
E. Elkaïm- will be available for the users during 2002 and installed on DW31.
Scientific Program
June, Thursday 6
Chairperson
9:15 – 10:00
(V
V. Etgens)
LURE Director's Report
10:00 – 10:45
Invited Lecture I
"Relating structure to mechanism in helicases"
Dale Wigley, London Research Institute (London)
10:45 - 11:15
Coffee break
Chairperson
11:15 – 12:35
(J. Daillant)
Selected talks (20 min.) Biology
"High pressure macromolecular crystallography" R. Fourme
"Structure of the matrix protein of Vesicular Stomatitis Virus" M. Gaudier
Selected talks (20 min.) Diffraction – Diffusion
"High temperature x-ray diffraction analyses of oxide layers formed on
zirconium alloys" J-L. Béchade
"High-pressure behavior of manganites investigated by x-ray diffraction and
optical spectroscopy" A. Congeduti
12:35 – 14:00
Lunch
Chairperson
14:00 – 14:45
(P. Lefèvre)
Invited Lecture II
"Grazing incidence scattering techniques to study nano-structured thin films"
Till Metzger, ESRF (Grenoble)
14:45 – 15:45
Selected talks (20 min.) Surfaces
"Quantitative GIXD measurements of microscopic forces in chemisorbed self
organised systems" B. Croset
"Adsorption modes of organic molecules on Silicon (001) 2x1 surfaces:
photoelectron analyses (XPS, NEXAFS) using the SCIENTA 200 at the SB7
beamline, complemented by STM" S. Kubsky
"Reaction kinetics and magnetic properties of the Mn/Fe(100) interface" P. Torelli
15:45 – 16:15
Coffee Break
Chairperson
16:15 – 17:55
(J.-P. Itié)
Selected talks (20 min.) Physiques du Solides
"XAFS study of short range order of thin films with picometer accuracy"
J. Purans
" Magnetic behaviour and magnetisation dynamics of exposed Fe nanoclusters "
P. Prieto
Selected talks (20 min.) Condensed Matter Chemistry
"Reversible lithium Intercalation in α-Fe2O3 nanoparticules" D. Bonnin
"Nanoscale bimetallic catalysts: is really bimetallic?" L. Guczi
"Study of photo-induced electron transfer by x-ray absorption and diffraction in
Co-Fe Prussian Blue analogues" A. Bleuzen
18:30 – 22:00
Posters and Discussions
June, Friday 7
Chairperson
9:00 – 9:45
(D
D. Dowek)
Invited Lecture III
"Advances in Synchrotron Radiation based Atomic and Molecular Physics"
Uwe Becker, Fritz-Haber-Institut der MPG (Berlin)
9:50 – 10:30
Selected talks (20 min.) Atoms and Molecules
"Photoionization of multiply charged ions" J.-P Champeaux
"HCl ionization at the surface of ice" F. Bournel
10:30 – 11:00
Coffee break
Chairperson
(D. Chandesris)
11h00 – 11:30 Invited Lecture IV
“An Overview of the Brazilian Synchrotron Light Laboratory”
Jose Brum, Associacao Brasileira de Tecnologia de Luz (Campinas)
11:30 –13:00
SOLEIL
♦ Progress report
♦ First selected beam lines
13:00 – 14:30
Lunch
Chairperson
14:30 – 17:00
(V. Etgens)
Selected talks (20 min.) Atoms and Molecules
“Absolute cross section measurement of the reactivity of stable doubly charged
molecular ions CO2++, implications for the martian ionosphere” R. Thissen
Users Committee report and Open discussion
♦ 2004-2006 … : Synchrotron experiment during the transition period
Invited lectures
Relating structure to mechanism in helicases
Dale B. Wigley
Cancer Research UK, Clare Hall Laborarories, South Mimms, Porters Bar, Herts EN6 3LD, UX.
In order Io try to understand more about the mechanism of helicases, we have determined crystal
structures of two different helicases complexed with DNA substrates. The mechanism that we
proposed for the Superfamily 1 (SFl) helicase, PcrA, involved ATP-dependent translocation
along single-stranded DNA. this suggestion was demonstrated directly by two different
biochemical methods in addition to the crystallographic evidence. However, we wished to test
the general applicability of this mechanism to helicases from other superfamilies.
To this end, we have now determined the structure of the Supeffarnily 2 (SF2) helicase, REGG,
in a complex with tés DNA substrate. a stalled rcplicetitm fork. The structure reveala how RecO
recognises ehis class ot DNA junctions. Furthermom ft pwsein bas been ampped in the initial
stages of unwindins DNA alkrwtng us to propose a mcchanism for this process. This mechwdsm
suggeste Chat RecG, and potentially other SF2 hehcases, are capark of ATP-depeMent
translocation along double-srronded DNA.
Grazing incidence scattering techniques to study nano-structured thin films
Till H. Metzger
ESRF (Grenoble)
We have developed x-ray scattering techniques at grazing incidence to analyse shape, strain and
ordering of nano-structured thin films on substrates, i.e. semiconductor quantum dots. In grazing
incidence small angle scattering (GISAXS) the morphology and the ordering of the dots is
characterised. Using grazing incidence diffraction (GID) the crystalline properties of the dots are
quantified, such as strain, shape, composition, and ordering. The beamline ID1 at the ESRF is
shown to be especially well suited for this kind of techniques. Results on different
semiconductor systems will be presented, demonstrating the versatility of the methods, which
can be applied to free-standing and buried dots.
Applying GISAXS to Ge islands grown on boron terminated Si(111) we find the shape and
size-distribution of nearly perfect triangular pyramids, incoherently connected to the substrate
[1]. While for the system InAs dots on GaAs (001) we find dome-like coherent InAs dots.
An “iso-strain-scattering” technique has been developed in the GID geometry to determine the
lattice parameter distribution and the chemical composition in dots. For free-standing InAs dots
the lattice parameter ranges from GaAs at the foot to InAs at the top of the dots. Clear evidence
for Ga inter-diffusion into the dots is found [2,3,4].
For QD embedded in multi-layers strong spatial correlations are expected. For Ge dots
embedded in SiGe (001) superlattices, self-assembling processes yield vertical and lateral dot
ordering. This ordering is quantified by applying a random walk argument to analyse grazing
incidence diffraction measurements. The Ge dots on the sample surface form a disordered lateral
square lattice [5]. The vertical stack ordering of the Ge dots increases with decreasing Si spacer
layer thickness [6].
In the system GaN/AlN QD multiplayer the vertical stacking of the GaN QD was quantified
from the analysis of Bragg sheets in the GISAXS region [7].
References:
[1] M. Rauscher, R. Paniago, H. Metzger, Z. Kovats, J. Domke, J. Peisl, H.-D. Pfannes, J.Schulze and I. Eisele,
J. Appl. Phys. 86, 6763 (1999)
[2] I. Kegel, T. H. Metzger, A. Lorke, J. Peisl, J. Stangl, G. Bauer, J. M. Garcia, P. M. Petroff, Phys. Rev. Lett.
85,1694 (2000)
[3] I.Kegel, T. H. Metzger, A. Lorke, J. Peisl, J. Stangl, G. Bauer,K. Nordlund, W.V. Schoenfeld and P. Petroff
Phys. Rev. B. 63, 035318 (2001)
[4] A.Malachias, R. Magalhães-Paniago, B.R.A. Neves,W. N. Rodrigues, M.V.B. Moreira, H.-D. Pfannes,
S. Kycia, T. H. Metzger Appl. Phys. Lett. 79, 1287 (2001)
[5] I. Kegel, T. H. Metzger, J. Peisl, P. Schittenhelm and G. Abstreiter; Appl. Phys. Lett. 74, 2978 (1999)
[6] I. Kegel, T.H. Metzger, J. Peisl, J. Stangl, G. Bauer, D. Smilgies; Phys. Rev.B, 60, 2516 (1999)
[7] V. Chamard, T. H. Metzger, E. Bellet-Amalric, B. Daudin, C. Adelmann, H. Mariette, G. Mula, appl. Phys.
Lett. 79, (13), 1971 (2001)
Advances in Synchrotron Radiation based Atomic and Molecular Physics
Uwe Becker
Fritz-Haber-Institut der MPG - Abteilung Oberflächenphysik - Faradayweg 4-6
DE 14195 Berlin - Germany
An Overview of the Brazilian Synchrotron Light Laboratory
J.-A. Brum
Director-General - Associacao Brasileira de Tecnologia de Luz Sincrotron - C.P. 6192
13084-971 Campinas (SP), Brazil
Oral Presentations
High pressure macromolecular crystallography : from high resolution
structure of a protein to the first experiments on crystallised macromolecular
assembly, cowpea mosaic virus
R. Fourme # , I. Ascone +, R. Kahn* , E. Girard* , M. Mezouar ++, T. Prangé +$ , J. E. Johnson§
# SYNCHROTRON SOLEIL, bât. 209H, Université Paris-Sud, 91898 Orsay cedex. +LURE, bât. 209D,
Université Paris-Sud, 91898 Orsay cedex; *IBS, 41 rue Jules Horowitz, 38027 Grenoble cedex;
++ESRF, BP220, 38027 Grenoble cedex; $ UMR 8015 CNRS, Faculté de Pharmacie, 4 Av. de
l'Observatoire 75270 Paris cedex 06 ; § Department of Molecular Biology, the Scripps Research
Institute, 10550N, Torrey Pines Road, La Jolla, CA 92037 USA
On beamline ID30 at the ESRF, the combination of a diamond anvil cell, ultra-short wavelength
X-rays from undulators (0.3305 Å) and a large imaging plate has allowed the extension of the
field of high-pressure macromolecular crystallography both for the accessible pressure range,
increased by one order of magnitude with respect to previous studies with beryllium cells, and
data quality. Results obtained on tetragonal hen egg-white lysozyme crystals at 7.0 kbar have
demonstrated that high pressure data can meet usual standards (resolution 1.6 Å, Rmerge 0.057,
multiplicity 7.2, completeness 0.93). These data were used for structure refinement. A detailed
comparison between the structures at normal and high pressure respectively is in progress.
The cowpea mosaic virus (CPMV) particle is the first example of crystallized macromolecular
assembly studied at high pressure. Single oscillation images of a cubic crystal of CPMV were
recorded at several pressures up to 4.4 kbar. The initial crystal (space group P23) at 1 bar, 1.1
and 2.0 kbar was disordered and diffracted to low resolution. At 3.3 kbar, a highly ordered I23
crystal was obtained, which diffracts at 2.6 Å resolution with high signal-to- noise ratio. Pressure
induces a first order transition; long range three dimensional order is most likely reached through
small rotations and translations of virus particles. At 4.4 kbar, the crystal no longer diffracted.
The ordering effect of high pressure observed for CPMV is quite interesting : High pressure
might indeed become a standard tool to improve order in macromolecular crystals, either by
favouring a more ordered packing or by restricting amplitudes of atomic motions in regions
which are disordered at atmospheric pressure.
In a broader perspective, the demonstration that accurate structural information on
macromolecular structures can be obtained at high pressure opens avenues such as exploration of
sub-states in protein crystals, study of interactions between macromolecules and between
subunits, and detection of the onset of pressure- induced denaturation. On the basis of these
advances, high pressure macromolecular crystallography has been included in the scientific case
of the avant-projet sommaire (APS) for a high pressure beamline at SOLEIL.
References
R. Fourme, R. Kahn, M. Mezouar, E. Girard, C. Hoerentrup, T. Prangé & I. Ascone (2001). High pressure protein
crystallography (HPPX): Instrumentation, methodology and results on lysozyme crystals. J. Synchrotron Rad. 8,
1149-1156.
R. Fourme, I. Ascone, R. Kahn, M. Mezouar, P. Bouvier, E. Girard, J. E. Johnson and T. Lin. Opening high-pressure
crystallography beyond 2 kbar on protein and virus crystals (submitted to Structure).
Structure of the Matrix protein of Vesicular Stomatitis Virus
Gaudier M. 1 , Gaudin Y. 2 , Knossow M. 1
(1) Laboratoire d'Enzymologie et Biochimie Structurales, Gif sur Yvette, France.
(2) Laboratoire de Génétique des virus, Gif sur Yvette, France.
The Vesicular Stomatitis Virus (VSV) matrix protein (M) interacts with cellular membranes,
self-associates and plays a major role in virus assembly and budding. We present the
crystallographic structure of a soluble thermolysin resistant core of VSV M determined at 1.96Å
resolution. The fold is a new fold shared by other vesiculovirus matrix proteins. The structure
accounts for the loss of stability of M Ts mutants deficient in budding and reveals a flexible loop
protruding from the globular core that is important for self-assembly (1).
Membrane floatation experiments have shown that, together with the M lysine-rich N-terminal
peptide that plays a major role in M membrane interactions, a second domain of the protein is
involved in membrane binding. Indeed, the structure reveals a hydrophobic surface located close
to the hydrophobic loop and surrounded by conserved basic residues that may constitute this
domain. Lastly, comparison of the structures of the mononegaviridae matrix proteins suggests
that the flexible link between the M major membrane binding domain and the rest of the
structure is a common feature shared by these proteins.
(1) Gaudier et all., Cleavage of vesicular stomatitis virus matrix protein prevents self assotiation and leads to
crystallisation. Virology 2001, 288, 308-314.
High temperature x-ray diffraction analyses of oxide layers formed
on zirconium alloys
J-L. Béchade1 , R. Brenner2 , P. Goudeau3 , M. Gailhanou4
1
CEA/DEN, SRMA, CEA/Saclay 91191 Gif Sur Yvette Cedex, France
LPMTM-CNRS, Institut Galilée, av. J.B. Clément, 93430 Villetaneuse, France
3
LMP-UMR 6630 CNRS, Université de Poitiers, B.P. 179, 86960 Futuroscope, France
4
LURE, Université Paris-Sud, 91405 Orsay Cedex, France
2
In zirconia layers formed by oxidation of zirconium alloys that are used in Pressurised
Water Reactor (PWR), the main monoclinic phase (stable at room temperature and atmospheric
pressure) coexists with the tetragonal phase, which may be stabilized by high compressive
stresses. The objective of this study is to link directly and if it is possible at a local scale, the
stress level in the oxide film to the volume fraction of tetragonal phase for Zr alloys of different
chemical compositions showing different oxidation kinetics.
Using x-ray laboratory diffraction techniques, this study is very difficult because of the
strong texture of the three phases associated to gradients of composition and stresses in the layer.
Moreover, up to now the residual stresses in the oxide layer have been determined after cooling
at Room Temperature (RT) and might be not representatives to the stress levels developed
during the growth of the oxide layer at 400°C due to the textures, elastic constants and thermal
expansion coefficients of the different phases [3]. That is why complementary analyses have
been engaged in our laboratory using a more intense X-ray source, with a parallel beam and a
wide range of wave lengths to allow stress levels in the oxide layer to be determined at high 2θ
angles to improve the precision of the measurements [1, 2].
We present here recent temperature measurements performed in situ using the H10
beam line at LURE. The results show that the stress levels in the oxide (monoclinic phase) are
consistent with the stress level previously determined at RT. These experimental results are in
agreeme nt with calculations of residual stresses due to the thermal anisotropic behaviour of the
monoclinic zirconia performed using a self- consistent thermoelastic.
Finally, we show the strong influence of the chemical composition of the Zr alloy and
the effect of the substrate texture on the oxidation kinetic, especially on the appearance of the
different phases.
References :
[1] « X-ray diffraction analysis of ZrO2 oxide layers formed on Zircaloy-4 plates corroded at 400°C in steam
», J.L. Béchade, P. Goudeau, M. Gailhanou, P. Yvon, ICRS5, Juin 1997, Linköping (Suède).
[2] «Studies of zirconium alloy oxide layers using synchrotron radiation», J.L. Béchade, R. Dralet, P. Goudeau,
P. Yvon, ECRS5, Septembre 1999, Delft-Noordwijkerhout, (Pays-Bas).
[3] Thesis N. Pétigny-Putigny, LRRS Université de Dijon, 1998.
High-pressure behavior of manganites investigated by x-ray diffraction
and optical spectroscopy
A. Congeduti1 , J.P. Itié 2 , P. Munsch2 , P. Postorino3 , A. Sacchetti3
1
2
L.U.R.E. Centre Universitaire Paris-Sud, Orsay - France, and Unita’ INFM Roma1, Italy.
L.U.R.E. Centre Universitaire Paris-Sud, Orsay - France, and Laboratoire de Physique des Milieux
Condenses, Universite’ Pierre et Marie Curie, Paris – France.
3
Dipartimento di Fisica and Unita' INFM, Universita' di Roma ''La Sapienza'', Italy
A lot of effort has been devoted to investigate physical properties of the Ruddlesden-Popper
series of manganites Ax A'n+1-x Mnn O3n+1 (with A a trivalent rare hearth and A' a divalent metal) [1]
which have been often regarded as reference systems for both high temperature superconductivity
and colossal magneto-resistance (CMR) phenomena. From a structural point of view the singlesheet (n=1) layered manganites are indeed isostructural to the Lax Sr2-x CuO 4 cuprates
superconductors, and their crystal structure is characterized by a planar arrangement of MnO 6
octahedra, which are the main building blocks of pseudocubic CMR manganites (A1x A'x MnO 3 )[2]. In n=1 layered manganites the octahedra are arranged in a 2-D structure with
MnO6 planes intercalated by planes of A ions while in pseudocubic manganites the A ions are
trapped inside a 3-D pseudocubic lattice of octahedra. It is interesting to note that single-layer
compounds show an insulating behavior regardless of doping concentration and temperature
while, in the doping concentration range where CMR occurs, pseudocubic manganites exhibit a
metallic phase associated to a ferromagnetic order below the I-M transition temperature TIM. The
occurrence of the metallic phase and of the CMR seems to be related to the crystalline structure,
which allows for a complete (pseudocubic) or at least a partial (bilayered) caging of the ion at the
A-site.
Quite recently we have investigated the pressure-behavior of pseudocubic manganites by
infrared and Raman spectroscopy [3,4,5,6]. In the present work we present a x-ray diffraction and
Raman study of La 0.5Sr1.5 MnO4 (LSMO) and Sr2 MnO4 (SMO) layered manganites, performed
over a wide pressure range (0-20 GPa) using a diamond anvil cell. The pressure dependence of
both lattice parameters and phonon peaks, as well as the mode-Gruneisen parameters, has been
determined.
The comparative analysis of the x-ray and Raman results allowed to give a reliable assignment
of the phonon modes observed in the Raman spectra and, in particular, to id entify the peak at the
highest frequency as a Jahn-Teller phonon [6]. The comparison of the pressure dependence of
doped and pure samples highlighted the relevance of the J-T octahedral distortion on the lattice
structural and dynamical properties [6]. This analysis, supported by the strong pressure
dependence exhibited by the mode-Gruneisen parameter of the J- T phonon in the doped sample,
reveals a progressive pressure- induced reduction of the J-T distortion. Finally, taking into account
of the results obtained by infrared and Raman spectroscopy on pseudocubic manganites [3], the
role of lattice dimensionality on the pressure- induced charge delocalisation process has been
outlined [6].
[1] Y. Moritomo A. Asamitsu, H. Kuwahara, Y. Tokura, Nature 380, 141 (1996).
[2] A. J. Millis, Nature 392, 147 (1998).
[3] A. Congeduti, P. Postorino, M. Nardone, E. Caramagno, A. Kumar, D.D. Sarma, Phys. Rev. Lett. 86, 1251 (2001).
[4] A. Congeduti, P. Postorino, P. Dore, A. Nucara, S. Lupi, S. Mercone, P. Calvani, A. Kumar, D.D. Sarma,
Phys. Rev. B 63, 184410 (2001).
[5] P. Postorino, A. Congeduti, P. Dore, F. A. Gorelli, A. Nucara, A. Sacchetti, L. Ulivi, High Press. Res. 00, 00 (2002).
[6] P. Postorino, A. Congeduti, E. Degiorgi, J.P. Itié, P. Munsch, Phys. Rev. B 65, 2241XX (2002).
Quantitative GIXD measurements of microscopic forces in chemisorbed
self-organised systems
B. Croseta, Y. Garreaub, Y. Girarda, R. Pinchauxb, G. Prévota, M. Sauvage-Simkinb, M. Sottoa
(a) Groupe de Physique des Solides, UMR-CNRS 75-88, Universités Paris 6 et 7, 2, place Jussieu,
75251 Paris Cedex 05, France.
(b) LURE, CNRS-MRES-CEA, Centre Universitaire Paris-Sud, 91898 Orsay Cedex, France.
Since the theoretical predictions of Marchenko1, surface elasticity is generally admitted to be the
driving force for self-organisation of bidimensionnal systems. Nevertheless, a measurement of the surface
stress discontinuities is still a challenge in spite of the importance of this parameter. Our study by grazing
incidence X-ray diffraction of the N/Cu(001) system allows us to evidence periodic bulk elastic relaxations
originating from the stress discontinuities. Therefore, a quantitative measurement of this stress
discontinuity can be obtained.
Previous works have shown that activated nitrogen adsorbed on Cu(001) leading to selforganisation2,3: the careful and extensive STM study of Elmer et al. shows that square shape domains of
c(2x2) structure are organised in rows, the intra-row period being constant and equal to 5.4 nm while the
inter-row period decreases with coverage to reach 5.4 nm around 0.8 coverage which corresponds to a
square array of domains.
We performed a grazing incidence x-ray diffraction study of the N/Cu(001) system on the 6-axes
diffractometre DW12 at LURE for several coverages between 0.4 and 0.8 monolayer5. Around each bulk
truncation rod (CTR), we observed diffraction satellites associated with the inter-row period. An
important point must be noted: the intensity of the satellites sharply increases for values of qper
approaching the Bragg condition of the bulk Cu. Such a feature cannot be explained if the diffracted
intensity is solely due to the periodic chemical contrast on the surface. On the contrary, it indicates that
the diffracting periodic object has as main spatial period in the direction perpendicular to the
surface, the interplanar distance of the bulk Cu crystal. Elastic relaxations of the substrate, which
should penetrate deeply in the crystal, seem therefore excellent candidates to explain the variation of the
satellite structure factors. For 0.8 coverage, the sharpness of the satellites allows to treat them as ordinary
rows and we were able to measure 262 structure factors. By using quenched molecular dynamics, we
compute the bulk elastic relaxations due to the surface stress discontinuity, ds, present on each domain
boundary. The quantitative value of this stress discontinuity is the main parameter used for the fit of the
diffraction data. We obtain a reliability factor of 0.06 for δσ = 2.4 10-9 N.at-1 = 7 N.m-1. This measure of
the stress discontinuity at a microscopic scale agrees perfectly with channelling RBS experiments6 which
indicate strong atomic disorder in the near surface region corresponding, in the elastic model, to
δσ = 2.2 10-9 N.at-1.
This quantitative analysis of the structure factors leads to the first direct evidence that surface
stress is the driving force for self-organisation of a chemisorbed system. It convince us that grazing
incidence X-ray diffraction will be a very useful tool in future studies of the physics of self-organised
systems.
References.
1. V. I. Marchenko, Sov. Phys. JETP, 54 605 (1982).
2. F.M. Leibsle, S.S. Dhesi, S.D. Barrett and A.W. Robinson, Surf. Sci., 317 309 (1994).
3. M. Sotto and B. Croset, Surf. Sci., 461 78 (2000).
4. H. Ellmer, V Repain, S. Rousset, B. Croset, M. Sotto, P. Zeppenfeld, Surf. Sci., 476 95 (2001).
5. B. Croset, Y. Girard, G. Prévot, M. Sotto, Y. Garreau, R. Pinchaux and M. Sauvage-Simkin, Phys. Rev. Lett., 88
056103.(2002)
6. C. Cohen, H. Ellmer, J.M. Guigner, A. L'Hoir, G. Prévot, D. Schmaus, M. Sotto, Surf. Sci., 490 336 (2001).
Adsorption modes of organic molecules on Silicon (001) 2×1 surfaces:
Photoelectron analyses (XPS, NEXAFS) using the SCIENTA 200 at the SB7
beamline, complemented by STM
S. Kubsky1 , F. Bournel1 , G. Dufour1 , J.-J. Gallet1 , S. Rangan1 , F. Rochet1 , F. Sirotti2
M. Kneppe3 , U.K. Köhler3 ,
N. Capron1 , S. Carniato1 , G. Boureau1
1
2
Laboratoire de Chimie-Physique, Matière et Rayonnement, Université Pierre et Marie Curie, UMR
7614, 11 rue Pierre et Marie Curie, F-75 231 Paris Cedex 5, France
Laboratoire pour l’Utilisation du Rayonnement Electromagnétique, Campus Paris-Sud, Bat. 209D, B.P.
34, F-91 898 Orsay Cedex, France
3
Institut für Experimentalphysik/Oberflächenphysik, Ruhr-Universität Bochum, D-44780 Bochum,
Germany
The understanding of the adsorption modes of organic molecules attached to the silicon
surface via their functional groups such as the C=C and the C≡N group, are of crucial interest for
various applications in semiconductor industry. Adsorption modes of a number of conjugated
and non-conjugated « nitriles » molecules (Acetonitrile, Acrylonitrile, Benzonitrile and
Allylcyanide) on the Si (001) 2×1 surface have been studied employing XPS and absorption
(NEXAFS) spectroscopy.
Valence-band (VB) and core- level (CL) photoemission spectra have been used to reveal
the formation of new chemical bonds at the surface during exposure to the gas. In this respect the
new experimental possibilities given by the SCIENTA 200 electron analyser were exploited.
« Snapshots » of a given kinetic energy (KE) window- measured in the so-called fixed mode can be recorded each 5 s in the present configuration. This « fast » CL/VB photoemission
experiments, performed as the surface is exposed to the gas, give interesting kinetical
information on the molecular adsorption process. The fixed mode is also used to record
« snapshots » of the Auger/VB region as a function of hν, more especially across an absorption
edge : the 3D- maps (KE, hν, Intensity) permit to work out well-defined Auger yield NEXAFS
curves of adsorbates (in the submonolayer range) on the Si surface. Analogously, resonant
Auger/photoemission data of the adsorbate can be extracted.
Using this new possibilities offered by the ABS6 experimental station, we have
performed a comprehensive study of the adsorption of these « nitriles » on Si(001). The
peculiarity of acrylonitrile is clearly evidenced. While the other nitriles bond preferentially via
addition of the CN moiety to one Si- Si dimer, acrylonitrile – a planar molecule – bridges the
trench between two dimers of two adjacent dimer rows. This leads to a flat lying geometry
clearly evidenced by angular dependent NEXAFS spectroscopy. These views are substantiated
by STM experiments performed in Bochum on the acrylonitrile and benzonitrile systems.
In the STM images, the signature of acrylonitrile adsorbed at 300 K is clearly non-static.
This has been evidenced by cooling the sample down to 80 K: the « movies » show that the
molecule occupies alternately two symmetric positions (the residence time in a given position is
of a few s at this temperature). These observations are supplemented by ab initio calculations
performed at LCPMR.
Reaction kinetics and magnetic properties of the Mn/Fe(100) interface
Piero Torelli*, Fausto Sirotti* and Pietro Ballone**
*Laboratoire pour l’Utilisation du Rayonnement Electromagnétique, Université Paris-SudB.P. 34, 91898
Orsay, France.
**Universitá di Messina, salita sperone, 31 c/o facolta di scienze mm.ff.nn., Messina, Italy
We have studied the formation of the Mn/Fe( 100) interface depositing Mn layers on a Fe(100)
single crystal. The electronic structure and the magnetic properties of the films were studied
using X-ray absorption and X-ray photoelectron spectroscopy with circularly polarized
synchrotron radiation in dichroism experiments.
The reaction kinetics of the deposited layers was followed in real time monitoring
simultaneously the intensities and line shapes of the Fe 3p and Mn 3p photoelectron peaks.
The annealing of the interface results in the formation of a Mn layer at the surface terminating
the Fe(100) lattice stable over a temperature range of about 100 K. The interdiffusion process is
also characterized from a binding energy shift of the Mn 3p photoelectron intensity.
The Mn Layer obtained with the annealing is magnetic and ferromagnetically coupled with the
Fe substrate. The orbital and spin magnetic moments of Mn atoms were determined from sum
rules applied to the XMCD spectra. Both orbital and spin moments are higher in the annealed
interface than in the original layer.
Molecular dynamics and MonteCarlo simulations of the Mn/Fe(100) interface shows the stability
of the 1 AL coverage and predicts an interdiffusion temperature in good agreement with the
experimental results.
XAFS study of short range order of thin films with picometer accuracy
J. Purans,1 A. Kuzmin,1 Y. Mathey2
1 - Institute of Solid State Physics, University of Latvia, Riga,
2 - GPEC, Faculté des Sciences de Luminy, Université de la Méditerranée, Marseille
XAFS spectroscopy using synchrotron radiation is extremely suitable technique to study local
atomic and electronic structure of nanocrystalline and amorphous thin films [1,2]. Despite of
XAFS technique overall success, the pico-meter barrier (10-2 Å) exists in an XAFS data analysis.
Recently it has been demonstrated that high accuracy XAFS measurements and new XAFS data
analysis software allowed to obtaine local structural parameters with picometer accuracy in solid
state [1].
Here we summarise the results of our XAFS investigations on mono- and multi-component
transition metal (5d, 4d and 3d) oxide thin films and chalcogenide compounds at the metals L
and K absorption edges. The XAFS spectra at the Ni, Co, Mo, Nb, Se, Te… K-edges and at the
Ta, W, Re L3 -edges have been recorded at LURE (Orsay) synchrotron radiation source. The
dependence of thin films local structure on composition, probed with picometer accuracy, and
new possibilities of XAFS data analysis will be presented.
Finally, we present XAFS studies of the local atomic structure of low dimensional transition
metal 1D and 2D compounds: niobium tellurides (NbTe 2 , Nb3 Te4 and NbTe 4 ) in comparison
with ZrTe 2 . Using a multi-shell best fit analysis procedure, we have reconstructed the local
environments of Nb and Te ions with picometer accuracy and compared them with the existing
structural models. We found that at Nb K-edge the XAFS data of NbTe 4 are extremely sensitive
to the metal clustering and to the subsequent departure from the average crystallographic
positions.
[1] Dalba G., Fornasini P., Grisenti R., Purans J., Phys. Rev.Lett. 82, L 4240 (1999).
[2] Y. Mathey, J. Purans, and H. Sassoli, Alloys and Compounds 262-263, L 81 (1997).
Magnetic Behaviour and Magnetisation Dynamics
of Exposed Fe Nanoclusters
C. Binns1, F. Sirotti2, S. H. Baker1, H. Cruguel3, P. Prieto4, S. H. Thornton1
1
Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH
2
LURE,CNRS, CEA, MESR, BP34, F-91485, France
3
ELETTRA Sincrotrone Trieste, Area di Ricerca, Padriciano 99, Trieste, Italy
4
Departamento Fisica Aplicada, C-XII, Universidad Autonama de Madrid, Spain
Films made from pre-formed magnetic nanoclusters are an important scientific challenge and
have enormous potential in the production of high-performance magnetic materials. Till recently
little was known about the magnetic behaviour of exposed clusters adsorbed on a surface in
UHV – especially the dynamical properties. We have studied the magnetic behaviour and
magnetisation dynamics of size-selected (1 – 5nm) exposed Fe nanoclusters deposited in situ
onto CoSi (vitrovac) substrates using a gas aggregation source. Magnetic alignment in the
clusters is maintained during photoemission measurements by exchange coupling with the
magnetic substrate. Magnetic Linear Dichroism in the Angular Distribution of photoelectrons
(MLDAD) shows that the evolution of the spin moment as a function of coverage depends on the
cluster size. We present evidence of a phase transition in particles of a specific size when they
come into contact, in agreement with recent TEM results. Coating the clusters with Co in situ
produces a significant increase in the Fe spin moment. The magnetisation reversal dynamics of
the clusters was determined by time-resolved secondary electron spin polarisation measurements
using the time structure of the synchrotron radiation from SuperACO. Experiments were carried
out as a function of temperature, cluster size and coverage. Cluster interaction induces a
significant change in the switching speed. The temperature and cluster-size dependence of the
dynamics will be presented.
Intercalation reversible du lithium dans des nanoparticules de α-FE2O3
Bonnin D.*, Larcher D.**, Juramy, C.*, Bodiguel H.*, Cortes R. +, Tarascon J.M.**
• * Laboratoire de Physique Quantique FRE 2312 ESPCI 10 rue Vauquelin 75231 Paris Cedex05
• **Laboratoire de Réactivité et Chimie des Solides UMR 6007, UPJV, 33 rue Saint-Leu, Amiens,
France
• + LURE Bât 209D Centre Universitaire - B.P. 34 - 91898 Orsay Cedex
De nouvelles approches ont été récemment initiées au LRCS, leur couplage pourrait ouvrir la
voie vers toute une nouvelle gamme de matériaux d’électrodes ayant des propriétés électrochimiques
originales et facilement contrôlables. Récemment, ce laboratoire a pu mettre en évidence qu’il est
possible d’orienter l’intercalation vers un processus monophasique et réversible, et ce par le biais de
l’utilisation de particules nanométriques de l’ordre de 20 nm. Ainsi, il était admis depuis le début des
années 1980 que l’hématite α-Fe2 O3 subissait une transformation structurale importante rendant cet oxyde
inapte à être le siège d’une réaction d’intercalation réversible. On mesure l’avancement de la réaction par
le seul courant électronique circulant à l’extérieur de la batterie, c’est à dire la charge globale.
Nous avons pu mesurer par Absorption des rayons X et spectrométrie Mössbauer les différentes
espèces présentes au sein de la batterie. La charge est donc ainsi donnée à partir de la composition interne
de la batterie (fer de degrés d’oxydation 0, 2+, 3+). Ces résultats sont bien sûr très importants puisqu’ils
permettent de comprendre les réactions au sein de la batterie.
5
200 Å
Fe2 O3 nanométrique
4.5
4
3.5
Voltage (Volts vs. Li+ /Li)
3
2.5
2
1.5
4.5
0
4
3.5
3
0.5
Fe2 O3 massif
1
2.5
2
1.5
1
0.5
0
0.5
x in LixFe2O3
1
Morphologie, taille et comportement électrochimique
d’oxydes α-Fe2 O3 nanométrique et massif.
Bien que la totalité de la capacité liée à ce couple
Fe3+/Fe2+ ne soit pas encore atteinte, son optimisation
permettrait d’atteindre une capacité réversible de
l’ordre de 170 mAh/g à un voltage moyen se situant à
2,5 Volts vs. Li+/Li, et une tenue en cyclage
considérablement améliorée.
Les modules de Transformées de Fourier ci-contre
montrent clairement le passage de Fe2 O3 (x=0, début
de la décharge) jusqu’au fer métal (x=7, fin de la
décharge).
L’étude des seuils d’absorption permet de
quantifier les concentrations des différentes
espèces et ainsi de comprendre les réactions
de réduction mises en jeu pour l’oxyde
métallique et les réductions secondaires.
Une comparaison est faite avec les résultats de la spectrométrie Mössbauer du fer qui permet de voir
également les différents états des atomes de fer (degré d’oxydation, taille des agrégats).
Nanoscale bimetallic catalysts: is it really bimetallic ?
L. Guczi1 , Z. Schay1 , L. Borkó1 and D. Bazin2 ,
1
Department of Surface Chemistry and Catalysis, Institute of Isotope and Surface Chemistry, CRC HAS,
P. O. Box 77, H-1525 Budapest, Hungary
2
LURE, Université‚ Paris XI, Bât 209D, 91405, Orsay, France
Decreasing the size of metallic particles to the range between 1-4 nm, the metallic character
does not exist anymore and the valence electrons are localized in discrete energy states, but their
properties is still far from that charateristic of molecular orbital. This transient state of the
electron structure is reflected in peculiar physical and chemical behaviors, consequently, in the
metal catalysis different activity is anticipated when nano-scale particles participate in the
reaction.
The character of the bimetallic catalysts is even more peculiar, because there are several
additional effects governing the character of the catalytic sites, such high metal dispersion, the
omission of the various intermetallic phases, strong metal support interaction and the increased
importance of the interface at the metal particles
The question arises what the role of the high dispersion is in the formation of bimetallic
particles. Application of several In situ physical and chemical surface techniques (EXAFS, XPS,
TPR, etc) is capable to elucidate whether, or not the macroscopic properties reflected in e.g.
reducibility, location of bimetallic particles on the support, etc. describe the micro-structure of
bimetallic particles. Ru-Co/NaY and Pt-Co/NaY bimetallic samples in various states (reduced,
oxidized states) have been studied. Theoretical approach verifies the usefulness of the in situ
EXAFS spectra providing structural information on the metal clusters in the bimetallic states. It
has been established that in some cases monometallic clusters maintains their identity, while in
other case the existence of bimetallic small particles can be established. The structure revealed
by EXAFS is able to explain the anomalies in the catalytic activity shown in the CO
hydrogenation.
REFERENCES
1
D. Bazin, P. Parent, C. Laffon, O. Ducreux, J. Lynch, I. Kovacs and L. Guczi, J. Synchrotron Radiat. New. 6,
430 (1999)
2
L. Guczi and D. Bazin, Appl. Catal. A., 188,163 (1999)
3
D. Bazin, P. Parent, C. Laffon, O. Ducreux, J. Lynch, I. Kovacs and L. Guczi, J. Catal, 189, 456 (2000)
4
L. Guczi, D. Bazin, I. Kovács, L. Borkó, and I. Kiricsi, Natural Gas Conversion VI. (Eds.: E. Iglesia, J. J.
Spivey and T. H. Fleisch) Stud. Surf. Sci. Catal.,136, 111 (2001)
5
L. Guczi, D. Bazin, I. Kovács, L. Borkó, Z. Schay, J. Lynch, P. Parent, C. Lafon, G. Stefler, Zs. Koppány and
I. Sajó, Topics in Catal, 20, (2002), in press
Study of Photo-Induced Electron Transfer by X-ray Absorption and
Diffraction in Co-Fe Prussian Blue Analogues
A. Bleuzen1 , V. Escax1 , M. Verdaguer1
C. Cartier , F. Villain2 , J.-P. Itié2 , P. Munsch2 , F. Baudelet2
2
1
Laboratoire de Chimie Inorganique et Matériaux Moléculaires, Université Pierre et Marie Curie, Bat F
E4, case 42, 4 place Jussieu, 75252 Paris cedex 05 (France).
2
Laboratoire pour l’Utilisation du Rayonnement Electromagnétique, CNRS-CEA-MENRS, Bat 209d,
Université Paris-sud, BP34, 91898 Orsay cedex (France)
The Prussian Blue Analogue of chemical formula K0,2 Co1,4 [Fe(CN) 6 ]•6.9H 2O is the first threedimensional compound to show photo-induced magnetic properties due to a metal-metal electron
transfer: CoIII(BS)-Fe II → CoII(HS)-Fe III 1 .
We determined the conditions required to observe the photo-induced process. X-ray absorption
spectroscopy (cobalt and iron K and L2,3 edges, EXAFS at the cobalt K edge) turned out to be a key
technique (2,3,4,5) which allowed us to evidence two necessary conditions: presence of CoIII-Fe II
diamagnetic pairs together with iron vacancies giving the network flexibility since the cobalt atom
undergoes a spin transition and a logical sizeable lengthening of its first neighbour bonds during the
electron transfer.
It is possible to tune the amount of diamagnetic pairs , or more generally to displace the :
CoIII(BS)-Fe II ↔ CoII(HS)-Fe III equilibrium by acting on internal strain such as the ligand field around
cobalt (chemistry) or external strains such as temperature or pressure. Once again, X-ray absorption and
X-ray diffraction under extreme conditions were well-adapted to evidence the electron transfers induced
by the various strains.
Electron transfers or spin transitions occurring under such conditions have been largely studied.
The originality of our compounds lies in the inorganic structure . In fact, Co and Fe are chemically
linked through short -CN- bridges in the three directions of space, whereas the usually studied
compounds are composed of isolated molecules in a crystal. How the face centred structure manage to
accommodate CoII(HS) and CoIII(BS) with different first neighbour bond length during the different
electron transfers ? Evidence of the macroscopic scale mechanism has been obtained using X-Ray
diffraction under irradiation.
References :
O
O
O
O
O
hν, T, P, ∆ Co
O
O
O
O
O
O
O
O
O
O
O
O
O
C-N
O
O
a = 10 Å
CoIII -FeII
1.
2.
C-N
O
O
a = 10.3 Å
CoII -FeIII
O. Sato, T. Iyoda, A. Fujishima, K. Hashimoto, Science., 1996, 272, 704-705.
A. Bleuzen, C. Lomenech, V. Escax, F. Villain, F. Varret, C. Cartier dit Moulin and M. Verdaguer, J. Am.
Chem. Soc., 2000, 122, 6648-6652.
3. C. Cartier dit Moulin, F. Villain, A. Bleuzen, P. sainctavit, C. Lomenech, V. Escax, F. Baudelet, E. Dartyge, J.J. Gallet and M. Verdaguer, J. Am. Chem. Soc., 2000, 122, 6653-6658.
4. V. Escax, A. Bleuzen, C. Cartier dit Moulin, F. Villain, A. Goujon, F. Varret, M. Verdaguer J. Am. Chem. Soc.
2001, 123, 12536-12543.
5. G. Champion, V. Escax, C. Cartier dit Moulin, A. Bleuzen, F. Villain, F. Baudelet, E. Dartyge, M. Verdaguer J.
Am. Chem. Soc. 2001, 123, 12544-12546.
Photoionization of multiply charged ions
(Absolute Measurements of Photoionization Cross Sections)
J.-P.Champeaux1,2, J.-M.Bizau1 , D.Cubaynes1 ,C.Blancard2 , J.Bruneau2 , S.Nahar3 , D.Hitz4 and
F. J.Wuilleumier1
1
LIXAM, Unité Mixte CNRS No.8624, Université Paris Sud XI, Bat 350, 91405 Orsay, France
2
Commissariat à l’Energie Atomique, CEA/DAM BP12, 91680 Bruyères-le-Châtel, France
3
Departement of Astronomy , Ohio State University, Columbus, USA
4
CEA-CENG, Service des Basses Températures, Grenoble, France
Because of its large abundance in astrophysical and laboratory plasma spectra, oxygen ions
are of crucial interest to be studied in order to interpret observations and, more generally, to
validate the different codes of atomic structure used for plasma model, such as R-Matrix or
MCDF codes. Recently, we have investigated photoionization of multiply charged ions of the
oxygen isonuclear sequences up to O4+ using the end-station for studies of photon- ion
interactions at the SU6 beamline undulator of Super ACO synchrotron radiation source in
Orsay (LURE). Absolute cross sections have been measured for O2+ and O3+ ions.
Figure 1
As an example, Figure 1 shows the photoionization cross section of O3+ on absolute scale,
measured over 67 to 99eV photon energy range. Some of the resonances have been identified
using both MCDF and R-Matrix [1] calculation. The resonances 1 to 7 (full bars on figure 1) are
belonging to a Rydberg series that is corresponding to the photoexcitation of the metastable state
2s2p2 (4 P1/2,3/2,5/2 ) of O3+ to 2s2pnd states with n>4. This Rydberg series converges to the 2s2p
threshold of O4+ at 87.5eV (MCDF results), above the 2s2 ground state threshold of O4+ observed
experimentally at 77.3 eV in figure 1. Our results on oxygen ions will be presented and discussed
at this meeting.
[1] S.Nahar and Al., Phys. Rev. Lett. 58, p 3766 (1991)
HCl ionization at the surface of ice
F. Bournel+, C. Mangeney+, M. Tronc +, C. Laffon* and Ph. Parent*
+
Laboratoire Chimie Physique, Matière et Rayonnement, Université P. et M. Curie, et CNRS UMR 7614
11 rue Pierre et Marie Curie, 75231 PARIS Cedex 05, France
*
Laboratoire pour l’Utilisation du Rayonnement Electromagnétique (LURE), CNRS - UMR 130, Bât 209 D, B.P.
34, Université Paris-Sud, 91898 ORSAY Cedex, France
The interaction (solvation, ionization, dissolution) of HCl with ice is still not well known although it is of
considerable implications in many areas such as heterogeneous chemistry in the atmosphere and interstellar space, biological
transformations on icy dusts and particulates, physical chemistry, in particular because HCl is one of the major products
resulting from dissociation of chlorofluorocarbons. Starting with the 1985 discovery of large seasonal loss of total ozone in
the antartic stratosphere due to the presence of polar stratospheric cloud (PSC) ice particles and their active role in
heterogeneous catalytic reactions [1], extensive efforts have been made both from the theoretical side and with laboratory
experimental approaches. In spite of these efforts, our understanding of HCl-ice interaction at the molecular level is still very
limited and a clear picture and detailed mechanisms for solvation, ionization and penetration of HCl in ice is lacking [2].
We have studied the adsorption of a HCl monolayer on an ice film under UHV conditions using near-edge X-ray
absorption spectroscopy (NEXAFS), both at the Cl2p (200 eV) and O1s edges (530 eV) [3]. This technique probes the bulk
of ice (>50 Å), but also, by detecting the photoions produced after the photoexcitation, the probing depth is reduced down to
2 Å and only the outmost layer of the ice surface is seen. This technique is called PSD-NEXAFS (Photo-StimulatedDesorption NEXAFS).
Fig. 1
Fig. 2
O1s, TIY
ion yield (arb. units)
electron yield (arb. units)
Cl2p, TEY
5s
0 mn
140 mn
1 ML HCl (120 K) / H2O Ih
HCl reference
4p
4s
5 mn
σ*(Cl-H)
200
205
210
215
220
Energy (eV)
225
230
530
535
540
545
550
Energy (eV)
Figure 1 compares the Cl2p NEXAFS spectra of a pure HCl film (bottom) with that of HCl adsorbed on ice
(top). The disappearance of the σ*(Cl-H) resonance when HCl is adsorbed on ice indicates the breakage of the Cl-H
valence bond. This directly evidences the HCl ionization on ice. In addition, the broad resonance at 221 eV will provide
structural informations on the solvation cage around the Cl- species within the ice network. Figure 2 presents the
evolution with time of the ice surface (measured in PSD-NEXAFS) before (0 min.) and after the HCl dosing (5 min., 140
min.). The strong decrease followed by the re -increase of the ion signal at the ice surface indicate that the ionized HCl
species slowly incorporate in the lattice and that the ice surface thus reconstructs. In addition, the PSD-NEXAFS
measurements at the Cl2p edge (not presented here) have shown that HCl is not molecularly adsorbed, and that its
ionization occurs directly at the surface. These results indicate that the reactivity of HCl with ice must be understood
mostly as a chemical interaction between ice and the chlorine ion, that at any step of the reaction.
[1] S. Solomon, R. R. Garcia, F. S. Rowland, D. J. Wuebbles, Nature 321, 755 (1986); M. J. Molina, T. L. Tso, L. T.
Molina, F. C. Wang, Science 238, 1253 (1987).
[2] B. J. Gertner, J. T. Hynes, Science 271, 1563 (1996).
[3] F. Bournel, C. Mangeney, M. Tronc, C. Laffon, P. Parent, submitted to Phys. Rev. Lett.
Absolute cross section measurement of the reactivity of stable doubly charged
molecular ions CO 2++, implications for the martian ionosphere
R. Thissen (1), J. Zabka (1) C. Alcaraz (2), O. Dutuit (1)
(1) LCP, Univ. Paris-sud, Orsay, France
(2) LURE, Univ. Paris-sud, Orsay, France
The molecular dication CO2 ++ presents a non- negligible production in the upper ionosphere of
mars. However, to determine its concentration, it was necessary to evaluate the major loss
channels of these ions. To this end, we have determined the absolute reaction cross section of the
stable dications with the major neutral species of mars ionosphere: CO2 . Using an MS/MS
device, we have produced the CO2 ++, either by photoionisation or by electron impact, and we
have measured the disappearance of the parent ion intensity in a cell filled with 13 CO2 . A value
of 45 Å2 is found for the loss of dication. The results show also that the reaction leads to charge
transfer or to collision induced dissociation, and that the branching ratio between these two
reactivities is depending on the internal energy content of the dication.
Those results were integrated in a model showing the presence of an ion layer in mars
ionosphere. The calculation of the dication CO2 ++ density in the atmosphere of Mars was
performed for the first time. The lifetime of these species reaches 4 seconds. A layer centered
around 155-160 km altitude can reach from 3 to and 5 *106 ions/m3 . The ions are produced by
the CO2 photoionization and photoelectron impact on CO2 . They are lost by dissociative
recombination with the thermal electrons and chemical reaction with CO2 . We suggest that this
ion layer is detectable by a mass spectrometer onboard the Mars 2007 orbiter.
Figure below presents the results of dication concentration modelisation, showing the presence of a CO2 ++ layer
in the outer martian atmosphere.
Posters
Posters
P01
Cryostat 4 K - 300 K for Transmission, Fluorescence, TEY Thermal properties of
Co, Cu clusters in matrices
C. Adjouri, F. Bouamrane, M. Ribbens, E. Fonda, A. Traverse
P02
Study of the formation of 2D and 3D mesotructured silica and organo-silica thin
films
B. Alonso, R. Balkenende, P.-A. Albouy, D. Durand, F. Babonneau
P03
Etude structurale de nanoparticules d'oxyde de magnésium enrobés
M. Benzakour
P04
Etude structurale de la décomposition d'oxaliplatine par des nucléophiles soufrés
par spectroscopie d'absorption des rayons X
D. Bouvet, K. Provost, E. Curis, I. Nicolis, S. Benazeth, S. Crauste-Manciet, D. Brossard
P05
Size effect on local magnetic moments in ferrimagnetic molecular complexes : an
XMCD investigation
G. Champion, M.-A. Arrio, Ph. Sainctavit, M. Finazzi, C. Mathonière, J.-P. Kappler,
M. Verdaguer, Ch. Cartier dit Moulin
P06
Réactivité des sites créés par le Rayonnement Synchrotron sur une surface de
diamant hydrogéné
K. Bobrov, G. Comtet, L. Hellner, G. Dujardin
P07
Adsorption du diphényl sur la surface de Si(100)-(2x1)
L. Soukiassian, K. Bobrov, M. Carbone, D. Riedel, G. Comtet, G. Dujardin, L. Hellner
P08
Intra-atomic versus inter-atomic processes in resonant Auger spectra at the Ti L2,3
edges in TiO2
J. Danger, P. Le Fèvre, H. Magnan, D. Chandesris, J. Jupille, S. Bourgeois, A. Verdini,
R. Gotter, A. Morgante
P09
Characterization of Silica Supported Tantalum Catalysts
A. De Mallmann, M. Taoufik, G. Saggio, C. Copéret, J. Thivolle-Cazat, J. M. Basset
P10
Optimisation de la presse Paris-Edimbourg pour la mesure de la densité et des
propriétés élastiques des matériaux sous conditions extrêmes
R. Debord, F. Decremps, D. Leguillon, G. Syfosse, M. Fischer, J.-P. Itié, A. Polian
P11
Study of the neutral products of the acetylene photolysis between 12 and 16 eV
S. Boyé, A. Campos, S. Douin, D. Gauyacq, A.L Roche et N. Shafizadeh
P12
Studying biological tissues using synchrotron infrared microspectroscopy
N. Gross, S. Marull, J.M. Ortega, T. Marin et P. Dumas
P13
Photoemission study of Fe-ZnSe(001) interface : Schottky-barrier height
M. Eddrief, M. Marangolo, G.-M. Guichar, V.H. Etgens, D.H Mosca, F. Sirotti
P14
Bidimensional segregation of mixed Langmuir films of hydrogenated and
fluorinated fatty acids
M.-C. Fauré, Ph. Fontaine, N. Puff, L. Tamisier, M. Goldmann
P15
Micro-XAS at the Swiss Light Source
A.-M. Flank, P. Lagarde, G. Cauchon, S. Bac, J.-M. Dubuisson
P16
Oxygen as a surfactant in the growth of (Co, Ni) / Al multilayers
E. Fonda, A. Traverse
P17
X-ray surface radiolysis : formation of metal-organic interface
Ph. Fontaine, F. Muller, S. Rémita, M. Goldmann
P18
Etude de la structure locale d'ions aqua d'éléments produits de fission à vie longue
par exafs: pd(ii) complexes
J. Purans, F. David, B. Fourest, S. Hubert, V.Sladkov, P. Baron
P19
Resonant auger spectrocopy on acrylonitrile multilayers, comparison with the gas
phase
J.-J. Gallet, F. Bournel, S. Kubsky, G. Dufour, F. Rochet, F. Sirotti, E. Kukk
P20
Elastic properties of supported polycrystalline thin films: an x-ray diffraction study
P. Goudeau, P. Villain, P.-O. Renault, K.F. Badawi
P21
X-ray diffraction from crystals under electric fields. Results on a-quartz
R. Guillot, P. All, P. Fertey, N.K. Hansen, E. Elkam
P22
Characterization of Th1-xUxO2 solid solutions by EXAFS
G. Heisbourg, J. Purans, N. Dacheux, and S. Hubert
P23
Photoemission studies of clean Si(100) surface and of Mn/Si(100)-H interface
formation
L. Lechevallier, R. Brochier, R. Flammini, C.M. Teodorescu, O. Heckmann,
C. Richter,V. Ilakovac, V.L. Than, A. Taleb-Ibrahimi, K. Hricovini
P24
XAS study of Chromium in Cr:Li2MgSiO4
C. Jousseaume, F. Ribot, F. Villain, A. Kahn-Harari, D. Vivien
P25
Study of amorphization by Alkali-Aggregate Reaction in SiO2 aggregate by XANES
and X-ray diffraction
J. Verstraete, L. Khouchaf, D. Bulteel, E. Garcia-Diaz, R. Cortès, A.M Flank,
M.H. Tuilier
P26
Structure and fragmentation dynamics of N2++ and NO++ ions
M. Ahmad, J.G. Lambourne, P. Lablanquie, J.H.D. Eland, R.I. Hall, F. Penent
P27
Autoionizing Neon Resonances Separated From Multiple Ionization Continua
J.G. Lambourne, P. Lablanquie , F. Penent, R.I. Hall, M. Ahmad, P. Hammond
P28
Quadrupolar transitions evidenced by resonant Auger
J. Danger, P. Le Fèvre, H. Magnan, D. Chandesris, J. Jupille, S. Bourgeois, T. Eickhoff,
W. Drube
P29
Imaging and time-of-flight resolved coincidence studies of dissociative
photoionization of small molecules
M. Lebech, J.-C. Houver, R.-R. Lucchese, D. Dowek
P30
Characterization and calibration of a silicon drift detector
M.-C. Lépy, L. Ferreux, Ch. Rémond
P31
Relevance of the drying step in the preparation by impregnation of Zn/SiO2
supported catalysts
C. Chouillet , M. Kermarec, H. Lauron-Pernot, C. Louis, F. Villain
P32
Caractérisation structurale d’ions par spectroscopie IR : couplage d’un piège à ions
FT-ICR avec le LEL IR
Ph. Maitre
P33
XAS study of the interaction of Pt species with basic sites in zeolites
P. Massiani, C. Pommier, L. Stievano, F. Villain
P34
Structure and morphology of thin cobalt films deposited on vicinal surface Cu(115)
A. Chaumin-Midoir, H. Magnan, L. Barbier, P. Le Fèvre, D. Chandesris, F. Scheurer
P35
DRX et EXAFS du Nb dans LiNbO3 fondu
B. Moulin , P. Simon , L. Hennet , D. Thiaudière, M. Gailhanou
P36
Etude de complexes Tb / antiinflammatoires non-stroïdiens par EXAFS
I. Nicolis, A. Rieutord, V. Hernando, E. Curis, P. Prognon, S. Bénazeth
P37
A Vacuum-ultaviolet study of fragments formed in the neutral photodissociation of
ethylene
J. O'Reilly, S. Douin, N. Shafizadeh, S. Boyé, Ph. Bréchignac, D. Gauyacq
P38
Metastable metallic phases formed at low temperature by Cs and Na on GaAs(001)
D. Paget, O.E. Tereshchenko, J.-J. Bonnet, P. Chiaradia, F. Wiame, R. Belkhou,
A. Taleb-Ibrahimi
P39
Raman and X-ray Absorption Spectroscopies for the determination of the
molybdenum symmetry in oxomolybdenum species: Application to supported
oxomolybdate catalysts
G. Plazenet, E. Payen, J. Lynch
P40
Study of an E-glass vitrifiable mixture fusion
S. Pédèche, G. Matzen, Ph. Melin, L. Hennet, D. Thiaudière, P. Forian, A. Douy
P41
Observation and characterization of the cinnabar phase in ZnSe at high pressure
J. Pellicer-Porres, A. Segura, V. Munoz, J.P. Itié, P. Munsch, A. Polian
P42
High-T coordination of Ln(III) in clay : in situ diffraction and XAFS
D.H. Powell, C. Pitteloud, H.E. Fischer, M. Gailhanou, J. Purans
P43
Square planar di-N-carboxamido, dithiolato-cobalt(III) complex related to the
Nitrile hydratase metallic site. Addition of axial ligands and oxygenation of the
sulfur atoms : an EXAFS study
K. Provost, L. Heinrich, Y. Li, A. Michalowicz
P44
Eu2+ and Eu3+ complexes in solid state and solutions
J. Purans, G. Moreau, L. Helm, A.-E. Merbach
P45
X-Rays absorption spectroscopy applied to layered magnetic materials using the
linear polarisation
M. Richard-Plouet, M. Guillot, D. Chateigner, A. Traverse, S. Vilminot
P46
EXAFS study of the hydrogenation in Ti-Zr-Ni quasicrystals and approximants
A. Sadoc, E.H. Majzoub, V.T. Huett, K.F. Kelton
P47
X-ray reflectivity study of the muscovite-water interface in KCl and CsCl solutions
M.L. Schlegel, K.L. Nagy, P. Fenter, N.C. Sturchio, L. Cheng
P48
Magnetic coupling in Co/Cu multilayers: field dependent antiferromagnetic
ordering investigated by resonant X-ray scattering
C. Spezzani, P. Torelli, M. Sacchi, R. Delaunay, C.-F. Hague, A. Mirone, R. Capelli,
F. Salmassi, E.- M. Gullikson, J.-H. Underwood
P49
IRMA: Instrument pour la Réflectivité Magnétique
M. Sacchi, C. Spezzani, R. Delaunay, A. Avila
P50
H10 : A material and high temperature beamline at DCI/LURE
M. Gailhanou, J.-M. Dubuisson, M. Ribbens, L. Roussier, D. Bétaille, C. Créoff,
M. Lemonnier, J. Denoyer, A. Jucha, A. Lena, M. Idir, M. Bessière, D. Thiaudière,
L. Hennet, C. Landron, P. Melin, Y. Auger, J.-P. Coutures
P51
Fe(II)-Fe(III) hydrolysis and complexation with As(III)-As(V) in the presence of
PO4 ions
S. Thoral, J. Rose, A.-M.Flank, J.-M. Garnier, J.-Y. Bottero
P52
Polyfunctional tris(oxalato)metalate based magnets : Structure and Magnetism
from X.A.S. and X.M.C.D.
C. Train, F. Pointillart, F. Villain, F. Baudelet, C. Giorgetti, Ch. Cartier dit Moulin,
M. Gruselle, M. Verdaguer
P53
Structural characterisation of the Ni-Al (111) interface by Surface X-ray Absorption
Spectroscopy
L. Damoc, E. Fonda, P. Le Fèvre, A. Traverse
P54
X-ray Absorption Spectroscopy of a strongly anisotropic bimetallic Iron-Cobalt
Ferromagnetic Double Chain : dehydration and magnetism
F. Villain, Ch. Cartier dit Moulin, M. Verdaguer, R. Lescouezec, M. Julve
P55
Non-rigidity in organometallic oxides
V. Artero, M. Bénard, P. Gouzerh, P. Herson, D. Laurencin, A. Proust, M.-M. Rohmer,
R. Thouvenot, F. Villain, R. Villanneau
P56
X-ray diffraction on liquid iron oxides - influence of oxygen partial pressure on
short-range order
G. Wille, L. Hennet, C. Landron, J.C. Rifflet, F. Millot, M. Gailhanou, D. Thiaudière
Post deadline
P57
Sources of radicals: application to the chemistry of planetary ionospheres
C. Alcaraz, C. Nicolas, R. Thissen, J. Zabka , O. Dutuit
P58
Soft X-ray absorption spectroscopy at the cutting edge for nanomaterials :
the state of art
D. Bazin, J. Rehr
P59
Optimisation d'une nanotechnologie liée à la Post combustion automobile : Étude
par EXAFS, RMN & DRX de catalyseurs industriels Zn/Al2O3
D. Bazin, R.Revel, I. Klur, A. Pourpoint
P60
An in situ Exafs study of the influence of the H2S/H2 ratio and the temperature on
the local order of Pd, Ni and Mo atoms in the case of a highly dispersed
multimetallic catalyst : Pd-Ni-Mo/Al2O3
F. Maire, D. Bazin
P61
Solid state concepts to understand catalysis using nanoscale metallic particles
D. Bazin
P62
Microfabrication using synchrotron radiation : LIGA
F. Bouamrane, T. Bouvet, R. Kupka, S. Megtert
P63
Ru-Co/NaY bimetallic catalysts: in situ exafs study at Co K- and Ru
K- absorption edges
D. Bazin, I. Kovács, J. Lynch, L. Guczi
P64
Soft x-ray grating spectrometer for high resolution resonant inelastic x-ray
scattering
C. F. Hague, J. H. Underwood, A. Avila, R. Delaunay, L. Journel, J.-M. Mariot,
J.-P. Rueff
P65
Resonant inelastic X-ray Scattering at L2,3 edges of CaF2 and ScAl2: configuration
interaction in the final state
L. Journel, J.-M. Mariot, J.-P. Rueff, C. F. Hague, M. Sacchi, C. Dallera, L. Braicovich,
G. Ghiringelli, A. Tagliaferri, M. Taguchi
P66
Catalyse Hétérogène et Rayonnement Synchrotron Bilan et Perspectives
D. Bazin, P. Parent, C. Laffon, E. Elkaim
P67
XMCD at LII,III edges or Er and K edges of Fe and Co in ErFe2 and ErCo2
C. Giorgetti
P68
Expériences couplées : SAX/ATP, SAX/Spectroscopie UV-visible at SAX/Raman
V. Briois, S. Belin, F. Bouamrane, F. Alves, F. Villain
P69
EPICEAAA Option I : first results
D. Céolin, C. Miron, M. Simon ; N. Leclercq, P. Morin
P70
CO adsorption on PtxPd1-x(111) single crystal alloy surfaces : a core level and
valence band photoemission study
N. Barrett
P71
Deep X-Ray LIGA at the Institut für Mikrotechnik Mainz GmbH
L. Singleton, A. Tunayan, O. Haverbeck, Ch. Krempel, R. Dinges, E. Weinbender,
P. Detemple
Cryostat 4 K – 300 K for Transmission, Fluorescence, TEY
Thermal properties of Co, Cu clusters in matrices
C. Adjouri*, F. Bouamrane°, M. Ribbens°, E. Fonda° and A. Traverse°
* LASMEA, Université Blaise Pascal, 24 Avenue des Landais, 63 177 Aubière
° LURE, Bât 209D, Centre Universitaire Paris-Sud. BP34. 91 898 Orsay Cedex
A new cryostat with helium bath (4K-300K) has been build up for X-ray absorption
spectroscopy with the aim to be used in the Transmission, Florescence and Total Electron Yield
(TEY) detection modes. The low temperature range 4K-300K can now be investigated and
extends the possibilities of previous cryostats working in Fluorescence and TEY detection modes
(80K-300K). We have checked the cryostat in Total Electron Yield. In this cryostat, the sample
is surrounded by Helium gas, thus the gas is ionized by the emitted electrons and acts as a
multiplier of the measured electron signal.
The evolution of the extended x-ray absorption fine structure (EXAFS) has been investigated by
temperature dependent measurements (20K-300K) on foils and clusters of Co and Cu (average
diameters about 0.9 nm). The first measurement (Figure 1) shows clearly a different evolution of
the bulk and the clusters indicating that thermal properties are size dependent.
The Debye temperature, the Debye –Waller parameter and its temperature evolution are
investigated in this work. The thermal evolution of the EXAFS data will be studied using a
cumulant analysis.
50
10
(a)
45
1
0.9
40
0.8
35
Co clusters - fcc
D = 9Å - 30 To 40 atoms
F(R)
(b)
1
8.5
0.95
8
8
0.7
30
6
0.9
7.5
0.85
7
Relative intensity
30
1.1
Relative intensity
F(R) : first peak max
40
50
F(R) : first peak max
Co foil - hcp
F(R)
0.8
6.5
0.75
0.6
25
0
50
100
150
200
250
300
6
350
0
50
100
T (K)
150
200
250
300
0.7
350
T(K)
20
21K
116K
197K
300K
4
23K
100K
10
189K
300K
2
0
0
2
4
6
R(Å)
8
10
0
0
2
4
R (Å)
6
8
10
Figure 1. Evolution of the modulus of the Fourier transforms F(R ) of the Co K- edge EXAFS
oscillation functions k3 χ (k) of (a) Co foil and (b) Co clusters .The figures in insert shows the
evolution of the first peak maximum F(R ) as a function of the temperature.
Study of the formation of 2D and 3D mesotructured silica
and organo-silica thin films
Bruno Alonso,a Ruud Balkenende, b Pierre-Antoine Albouy, c Dominique Durand,d and Florence
Babonneaue
a
CRMHT, CNRS UPR 4212, 1D av. de la Recherche Scientifique, 45071 Orléans Cedex 2, France.
alonso@cnrs-orleans.fr
b
c
Lab. de Physique des Solides, Université Paris-Sud, 91405 Orsay Cedex, France.
d
e
Philips Research Lab., Prof. Holstlaan 4, 5656 AA Eindhoven, Netherlands.
LURE, bât. 209D, Centre Universitaire, BP 34, 91898 Orsay Cedex, France.
Lab. Chimie de la Matière Condensée, Université P. et M. Curie, 75252 Paris Cedex 05, France.
Important advances have been made recently in the formation of ordered mesoporous oxide thin
films. In the case of silica, the identification of porous structures, their selective formation from
adequate chemical conditions, and the study of the underlying mechanisms have been studied.
We took advantage of this emergent knowledge to optimise and understand the formation of
silica and organo-silica mesostruc tured thin films.
Our synthetic procedure has been simplified to its maximum in order to reduce the number of
parameters. It was based on the three following steps:
1) hydrolysis by aqueous HCl (10-1 or 10-2 M) of ethanolic solutions containing the precursors
(Si(OEt)4 , PhSi(OEt)3 , MeSi(OEt)3 ) and the surfactant (CTAB).
2) deposition of the films by dip-coating;
3) stabilisation of the network and removal of the surfactant by a combination thermal
treatments and ethanol extraction.
We investigated the relationships between mesotructures (p6mm, P63 /mmc, Pm3n) determined
by ex situ and in situ small angle X-ray diffraction techniques, and chemical parameters (nature
of the precursors, pH, surfactant/silicon molar ratio, sol ageing times). The dependence on HCl
content was found to be one of the most important parameters. In this sense, we studied the
advancement of hydrolysis and condensation reactions by spectroscopic techniques such as 29 Si
liquid-state NMR. Also, we demonstrate the directing role of vapour ethanol concentration
during film formation. Modifications of these two parameters (pH, EtOH) allow to obtain by dip
coating the three different mesostructures.
Etude structurale de nanoparticules d’oxyde de magnésium enrobés
M. Benzakour
Groure de Physique des Milieux Denses, Créteil, France
Avec une grande surface spécifique et à une porosité assez importante, les nanoparticules
d’oxydes d’alcalino-terreux présentent une grande réactivité, celle-ci peut être augmentée en
enrobant ces nanoparticules d’une couche d’oxyde métallique tel que l’oxyde ferrique (Fe2O3).
De telles entités chimiques sont capables de décomposer les gaz polluants comme CCl4 ou SO2
et de stocker la fraction polluante à l’intérieur de la nanoparticule.
Le mécanisme peut être décrit en deux étapes : une réaction de surface où la molécule du
gaz polluant réagit avec l’oxyde métallique, puis une réaction entre cet enrobage et le volume de
la nanoparticule : la fraction toxique du gaz polluant est finalement piégée à l’intérieur de la
nanoparticule.
Afin de mieux comprendre ces mécanismes du point de vue structural une étude
par spectroscopie d’absorption des rayons X a été engagée, la partie EXAFS du spectre
d’absorption nous permet de connaître l’ordre local de l’alcalino-terreux et de l’oxyde de
l’enrobage. Ce dernier étant très désordonné, la diffraction des rayons X n’a pas pu nous donner
de renseignements sur la structure de la surface.
Nous montrerons les résultats obtenus sur les nanoparticules de MgO enrobées avec
Fe2O3 avant et après réaction avec CCl4.
Etude structurale de la décomposition d’oxaliplatine par des nucléophiles soufrés
par spectroscopie d’absorption des rayons X
Diane Bouvet (1), Karine Provost (1), Emmanuel Curis (2) ,Ioannis Nicolis (3), Simone Benazeth
(2,3)
,Sylvie Crauste-Manciet (4,5), D. Brossard (4,5)
(1) Groupe de physique des milieux denses, Université PARIS XII, France
(2) LURE, Bat. 209 D, Centre Universitaire Paris-Sud, Orsay, France
(3) Laboratoire de biomathématique, Faculté de pharmacie, Université Paris V, France
(4) Laboratoire de pharmacie Galénique, Université Paris V, France
(5) CHI Poissy - Saint Germain en Laye, Saint Germain en Laye, France
e-mail: bouvet@univ-paris12.fr
Mots-Clefs : oxaliplatine, spectroscopie, soufre.
Depuis la découverte du cisplatine, les complexes de platine (II) ont suscité un vif intérêt en
chimiothérapie1. Un des complexes de deuxième génération, l’oxaliplatine (figure), est utilisé en
France comme alternative au cisplatine dans les cancers colo-rectaux .
C
H2
N
O
O
C
Pt
C
N
H2
O
C
O
L’oxaliplatine présente une haute réactivité aux nucléophiles en solution 2. Cette propriété
peut d’une part, compromettre les effets pharmacologiques par la production d’autres
métabolites, et d’autre part compromettre la stabilité de l’anticancéreux avant administration. De
plus, l’interaction entre l’oxaliplatine et ces composés 3in vivo pourrait expliquer ses toxicités
différentes vis a vis des autres anticancéreux de platines .
La spectroscopie d’absorption X est une technique particulièrement adaptée à ce type d’étude,
puisqu’elle permet de suivre l’évolution de la sphère de coordination du platine et ce, en solide
ou en solution. Dans un premier temps, nous avons mis au point les conditions de simulation sur
des complexes de structure connue. Ces modélisations ont conduit à la mise en évidence des
caractéristiques des deux ligands (oxalate et cyclohexanediamine) dans le spectre de l'
oxaliplatine.
Dans un deuxième temps, nous avons étudié l’effet de différents nucléophiles sur
l’oxaliplatine, le diéthyldithiocarbamate
et le thiosulfate, qui protègent tous deux contre la
néphrotoxicité du platine 4. La caractérisation des produits de réaction a permis de montrer le
déplacement du cyclohexane diamine par les nucléophiles soufrés. Cette étude complète les
travaux effectués5, par
notre équipe sur le comportement des complexes de platine en présence
d’ions chlorures 6.
1
Long, DF, Repta AJ, Biopharm Drug Dispos. 1981, 2, 1-16.
Reedijk J, Hanbook of metal ligand interaction in biological fluids, 967-989.
3
Roberts JJ, Pera MP Jr, Molecular aspects of anti-cancer drug action, 83, 183-231.
4
Dedon PC, Borch RF, biological pharm, 1987, 36, n°12, 1955-64.
5
Curis E, Provost K, Nicolis I, Bouvet D, Benazeth S, Briond F, Crauste-Manciet S, Brossard D, New J. Chem,
2000, 24, 1003-8.
6
Curis E, Provost K, Bouvet D, Nicolis I, Crauste-Manciet S, Brossard D, Benazeth S, J. synch rad, 2001, 8, 71618.
2
Size effect on local magnetic moments in ferrimagnetic molecular complexes :
an XMCD investigation
Guillaume Champion, 1,2 Marie-Anne Arrio,3 Philippe Sainctavit,1,3 Marco Finazzi, 4 Corine
Mathonière,5 Jean-Paul Kappler,6 Michel Verdaguer,2 Christophe Cartier dit Moulin1,2 *
1
Laboratoire pour l’Utilisation du Rayonnement Electromagnétique, BP34, Université Paris-Sud, 91 898
Orsay cedex, France
2
Laboratoire de Chimie Inorganique et Matériaux Moléculaires, Université Pierre et Marie Curie, 4
place Jussieu, 75 252 Paris cedex 05, France
3
Laboratoire de Minéralogie Cristallographie de Paris, Universités Paris 6 et 7, 4 place Jussieu, 75 252
Paris cedex 05, France
4
Elettra, Sincrotrone Trieste ScpA, Experimental Division, S.S. 14 Km. 163.5, 34012 Basovizza, Trieste,
Italy
5
Institut de Chimie de la Matière Condensée, 87, Avenue du Docteur Schweitzer, 33608 Pessac cedex,
France
6
Institut de Physique et Chimie des Matériaux de Strasbourg, 23, rue du Loess F - 67037 Strasbourg
cedex, France
Molecular chemistry allows to synthesise new magnetic systems with controlled
properties such as size, magnetisation or anisotropy. The theoretical study of the magnetic
properties of small molecules (from 2 up to 10 metallic cations per molecule) predicts that the
magnetisation at saturation of each ion does not reach the expected value for uncoupled ions
when the magnetic interaction is antiferromagnetic. The quantum origin of this effect is due to
the linear combination of several spin states building the wave function of the ground state and
clusters of finite size and of finite spin value exhibit this property. When monocrystals are
available, spin densities on atoms can be experimentally given by Polarised Neutron Diffraction
(PND) experiments. In the case of bimetallic MnCu powdered samples, we will show that X-ray
Magnetic Circular Dichroism (XMCD) spectroscopy can be used to follow the evolution of the
spin distribution on the MnII and CuII sites when passing from a binuclear MnCu unit to a one
dimensional (MnCu) n compound.
Keywords : X-ray absorption spectroscopy, XMCD, quantum size effects.
Réactivité des sites créés par le Rayonnement Synchrotron sur
une surface de diamant hydrogéné
K. Bobrov1, G. Comtet1, 2, L. Hellner1, 2, G. Dujardin1, 2
1) Laboratoire de Photophysique Moléculaire
Bât 210, Université Paris-Sud, 91405 Orsay Cedex, France
2) Laboratoire pour l'Utilisation du Rayonnement Electromagnétique (LURE)
Bât. 209 D, Centre Universitaire Paris-Sud, BP 34, 91898 Orsay Cedex, France
Après irradiation par le faisceau sans sélection spectrale de Super ACO, les surfaces
hydrogénées de silicium et de diamant (100)2x1 présentent des sites originaux. Ces sites originaux ont
été mis en évidence par leur signature spectrale en photoémission dans la bande de valence et
NEXAFS (1, 2). Ces nouveaux sites ne sont pas présents sur les surfaces hydrogénées, partiellement
déshydrogénées par chauffage et complètement déshydrogénées. Nous étudions ici leur réactivité
chimique spécifique.
L’oxygène moléculaire réagit avec la surface de diamant partiellement déshydrogénée par
irradiation alors qu’il ne réagit pas avec les surfaces de diamant hydrogénée, de diamant partiellement
déshydrogénée par chauffage, de diamant complètement déshydrogénée. Ces études ont été menées
par photoémission dans la bande de valence, la diminution ou la stabilité de l’intensité des bandes
associées aux états de surface du diamant étant la signature d’un processus d’adsorption ou d’une
absence d’adsorption.
Ces résultats mettent en évidence la réactivité spécifique de ces sites créés par irradiation, c. à
d. par excitation électronique. Dans le cas d’un chauffage, la désorption simultanée des deux atomes
d’hydrogène d’un dimère conduit à la formation d’une liaison π entre les deux atomes de carbone du
dimère, liaison qui ne s’ouvre pas pour accueillir l’oxygène. Dans le cas d’une irradiation, l’excitation
électronique produit la désorption d’un des atomes d’hydrogène du dimère et donc la création d’une
liaison pendante σ avec laquelle l’oxygène réagit.
Le même type d’étude, la réactivité spécifique des sites créés par irradiation d’une surface
hydrogénée, a été réalisé dans le cas du silicium hydrogéné (3). L’interprétation des résultats dans ce
cas est moins immédiate car l’oxygène moléculaire, bien que ne réagissant pas avec les dimères de la
surface de Si(100)2x1, réagit avec les défauts de surface. Les études sur les surfaces de diamant ont
l’avantage d’avoir des résultats directement interprétables.
(1) K. Bobrov, G. Comtet, L. Hellner, G. Dujardin, Phys. Rev. Lett. 84, 2255 (2000).
(2) K. Bobrov, G. Comtet, G. Dujardin, L. Hellner, P. Bergonzo, C. Mer Phys. Rev. B63, 165421 (2001).
(3) G. Comtet, G. Dujardin, L. Hellner, communication privée
Adsorption du diphényl sur la surface de Si(100)-(2x1)
L. Soukiassian1, K. Bobrov1, M. Carbone2, D. Riedel1, G. Comtet1,3, G. Dujardin1,3, L. Hellner1,3
1. Laboratoire de Photophysique Moléculaire, Université Paris-Sud, Orsay
2. Dip. Di Scienze e Tecnologie, Università Tor Vergata,, Roma, Italy
3. Laboratoire pour l’Utilisation du Rayonnement Electromagnétique, Université Paris-Sud, Orsay
Nous avons étudié l’interaction du diphényl avec les surfaces de Si (100)-(2x1). Ces
études s’inscrivent dans le cadre d’une recherche de molécules organiques susceptibles de
conduire le courant électrique et de jouer ainsi le rôle des composants électroniques.
La molécule de diphényl possède deux cycles benzéniques. Nous l’avons d’abord étudiée
en phase condensée (80 K) et comparée au benzène condensé. Le spectre NEXAFS du diphényl
condensé possède comme celui du benzène condensé deux résonances π∗. Les énergies des
premières résonances π∗ sont dans les deux cas de 284.6 +/- 0.2 eV (calibration à partir des
résonances du diamant) et leurs largeurs sont équivalentes. La deuxième résonance π∗ est 3.8 eV
plus haut dans le cas du benzène et 4.0 eV plus haut dans le cas du diphényl. Les énergies des
résonances associées aux orbitales σC-H et aux deux orbitales σ∗C-C ont été mesurées. Rappelons
que le couplage des orbitales p des 6 atomes de carbone du benzène crée deux orbitales π∗, la
première étant doublement dégénérée. Le diphényl qui a deux cycles benzéniques est lui aussi
caractérisé par deux orbitales π∗.
Nous avons déposé 0.5 Langmuir de diphényl sur la surface de Si (100)-(2x1) à
température ambiante, ce qui correspond à un recouvrement de la surface bien inférieur à la
monocouche. Le spectre NEXAFS associé ne présente qu’une résonance π∗ à 284.6 eV, un peu
plus large que la résonance π∗ du diphényl condensé (1.15 eV au lieu de 1.03 eV). La résonance
σC-H* est toujours à 2.1 eV au-dessus de la résonance π∗. Les faibles taux de comptage rendent
difficiles la mesure des énergies des résonances σ*. Quand l’adsorption du diphényl a lieu sur la
surface de Si (100)-(2x1) portée à 80 K, l’intensité de la première résonance π∗ du spectre
NEXAFS est multipliée par 1.4, sa position est inchangée et sa largeur augmente de 0.3 eV. De
plus, la deuxième résonance π∗ qui n’apparaissait pas à 300 K est présente à 80 K. Le caractère
π∗ de cette résonance est déduit d’une étude angulaire.
Ces résultats nous permettent de conclure qu’à 300 K, les molécules de diphényl sont
chimisorbées et ne possèdent plus de noyau benzénique (présence d’une seule résonance π*).
Par contre, dans le cas d’une adsorption à 80 K, il existe encore des noyaux benzéniques
(présence de deux résonances π*) ; la présence simultanée de cycles chimisorbés et de cycles
physisorbés expliquerait pourquoi la résonance π∗ à 284.6 eV est plus large pour le diphényl
adsorbé à 80 K que pour le diphényl condensé.
Des études XPS nous ont permis de déterminer l’énergie de la première résonance π∗ par
rapport au niveau de Fermi. Ce positionnement est important pour connaître le mode de transfert
des électrons de la molécule adsorbée à la surface.
Intra-atomic versus inter-atomic processes in resonant Auger spectra at the Ti
L2,3 edges in TiO 2
J. Danger1,2, P. Le Fèvre1 , H. Magnan1,2, D. Chandesris 1 , J. Jupille3 , S. Bourgeois4 , A. Verdini6 ,
R. Gotter6 and A. Morgante6,7
1
LURE, CNRS-Université Paris Sud, Bât. 209d, BP34, 91898 Orsay cedex, FRANCE
2
SPCSI, CEA Saclay, 91 191 Gif sur Yvette, FRANCE
3
GPS, CNRS-Université Paris VI et VII, 2 place Jussieu, 75251 Paris cedex 05, FRANCE
4
LRRS, CNRS -Université de Bourgogne, BP47870, 21078 Dijon cedes, FRANCE
5
TASC-INFM, 34012 Basovizza, Trieste, ITALY
6
Dipartimento di Fisica, Universita’ degli studi, Trieste, ITALY
The chemical nature and environment of an element often manifest themselves through the
occurrence of specific electronic transitions. In ionocovalent compounds, the severely depleted
valence population of the cations favors a possible interatomic core hole Auger decay.
Furthermore, it has been evidenced recently that core level electrons of neighboring atoms can be
direct actors in the resonant photoemission process of the excited atom which can have
applications as a probe of the hybridization with the external orbitals of neighboring atoms [1].
In transition metal oxides, the occurrence of interatomic transitions in Auger decays involving
valence electron has suggested to make use of them to determine the surface stoichiometry. In
TiO 2 , the stoichiometry has been shown to be directly related to the ratio of the two components
of the Ti L23 M23 V Auger transition [2]. Due to its appearance when the metal is oxidized and its
increase in intensity upon increasing the oxidation state of the metal, the low kinetic energy
component is assigned to a so-called “interatomic LMV(O)” decay, while the other component is
associated to an “intra-atomic LMV(Ti)” process (V(Ti) and V(O) refer to Ti and O
contributions to the oxide valence band).
In this work, the two components of the Ti L2,3M2,3V Auger transition recorded on a
stoichiometric rutile crystal are identified as L2 M2,3V and L3 M2,3V contributions. This
assignment is evidenced by concordant data relative to resonances of the LMV decay at the Ti
L2,3 thresholds and to Auger emission recorded in coincidence with the 2p1/2 and 2p3/2
photoemission at a photon energy far above the Ti L2,3 edges. The L3 M2,3 V transition is shown to
follow either the direct photoexcitation of a 2p3/2 electron or the fast Coster-Kronig decay of a
2p1/2 photohole. Although specific LMV contributions related to valence orbitals are identified,
the long-suggested dual description of the L2,3M2,3V Auger line as intra-atomic and interatomic
transitions is discarded.
References
[1] M. Garnier et al., MAX Lab report and submitted to Phys. Rev. B; A. Kay et al., Science 281, 679 (1998).
[2] C.N. Rao, D.D.Sarma, Phys. Rev. B 25, 2927 (1982).
Characterization of Silica Supported Tantalum Catalysts
A. De Mallmann*, M. Taoufik, G. Saggio, C. Copéret, J. Thivolle-Cazat, J. M. Basset
L.C.O.M.S.; UMR9986 CNRS/CPE-Lyon; 43, Bd du 11 Novembre 1918
69616 Villeurbanne cedex - France
X-ray absorption spectroscopy has been used to study several silica supported tantalum
species used as catalyst precursors or which are presumed intermediates (i) in alkane metathesis
reactions (e.g. 2 C2 H6 → CH4 + C3 H8 ) or (ii) in the asymmetric epoxidation of allyl alcohols
(e.g. H2 C=CH-CH2 OH + ROOH → H2C
O
CHCH2OH + ROH). The first step in the preparation
of these species is the grafting of tantalum trisneopentyl neopentylidene Ta(=CHt-Bu)(Np)3 onto
silica. The solids were then treated under hydrogen or by an alcohol to lead respectively (i) to
TaIII species or (ii) to Ta V surface alkoxides. The samples were characterized by different
techniques including microanalysis, IR and solid state NMR (1 H,
13
C,
31
P). Then they were
studied by EXAFS at the LIII edge of tantalum (E0 = 9881 ev) to get information on the structure
of the supported species which could valid, precise or infirm the models we could propose from
other characterization techniques and inspired by model compounds known in molecular
organometallic and inorganic chemistry. The scheme below will be presented and discussed in
detail in the poster
H
O Ta
O
Si
O Si
PMe3
H
Si
H2
O
O Si
O
O
O
Si
O Si
Si
Si
OEt
EtO
Ta
Ta
O
PMe3
H
O
EtOH
Si
Si
H2
Ta
O
O
Si
O Si
O
Si
C5 H10
CH
Ta
O
H2
Np
Np
Si
EtOH
OEt
OEt
Ta OEt
EtO
O
O
Si
Si
Si
O Ta
O
Si
O Si
OEt
O Ta O
t-Bu O
O
O
Si
200ºC
2 H2
COOEt
COOEt
O Ta
O
Si
O Si
O
O Ta O
COOEt
t-Bu O
O
COOEt
O
Si
(?)
Optimisation de la presse Paris-Edimbourg pour la mesure de la densité et des
propriétés élastiques des matériaux sous conditions extrêmes
Régis DEBORD, Frédéric DECREMPS, *Dominique LEGUILLON, Gérard SYFOSSE, Myriam
FISCHER, Jean Paul ITIE, Alain POLIAN
PMC (UMR 7602 CNRS/UPMC) Tour 13 E2, 4 Place Jussieu 75252 Paris Cedex 05
* LMM (UMR 7607 CNRS/UPMC) 8 Rue du Capitaine Scott 75015 Paris
La presse Paris-Edimbourg permet de réaliser simultanément des mesures de vitesses de
propagation d’ondes ultrasonores dans des échantillons contraints (P ≅ 7 GPa) et de diffraction X
à température ambiante. Nous présentons ici une étude par éléments finis d’un four entourant
l’échantillon afin d’effectuer ces mesures jusqu'à 1000 K.
Dans un joint en bore-époxy (dont le diamètre extérieur est de 10mm) qui sert à confiner et à
transmettre la pression se trouvent l’échantillon à étudier, le nitrure de bore (BN) utilisé comme
isolant électrique et comme milieu transmetteur de pression et une poudre de sel. La poudre de
sel compactée est utilisée à la fois comme milieu transmetteur de pression et comme calibrant
pour déterminer la pression in situ. Celle ci est mesurée en étudiant le déplacement des raies de
diffraction de rayons X du sel avec la pression et en ajustant les résultats avec l’équation d’état
établie par Decker (1965), pour des pressions inférieures à 30 GPa. Une ouverture de la culasse
de la presse permet le collage d’un transducteur piézoélectrique sur le noyau en carbure de
tungstène de l’enclume supérieure. Les transducteurs, pour l’étude d’échantillons millimétriques,
sont en LiNbO3 et ont une fréquence de résonance comprise entre 10 et 30 MHz. Ainsi par la
mesure du temps de transit de l’onde ultrasonore dans l’échantillon on peut déterminer les
constantes élastiques du matériaux étudié en fonction du chemin thermodynamique suivi. Afin
d’obtenir les hautes températures une différence de potentiel est appliquée entre les deux
enclumes de la presse, permettant ainsi le chauffage par effet joule de l’échantillon via un four
tubulaire en graphite amorphe.
Une approche thermique du dispositif expérimental a été menée sur un code de calcul d’éléments
finis nommé Modulef, au Laboratoire de Modélisation en Mécanique (LMM) de l’Université
Pierre et Marie Curie. Le but de cette étude est de définir un volume expérimental
thermiquement homogène et techniquement réalisable. Les premiers calculs ont permis de
montrer que la forme et la valeur des isothermes à l’intérieur du four dépendent de trois critères
importants :
- la nature du matériau utilisé comme amené de courant ;
- la géométrie de ces contacts ;
- la géométrie du four et de ses isolants internes (nitrure de bore).
Références :
Besson, J.M. et al. 1992, Physica, 180&181, pp. 907
Decremps F. 1998, Propriétés structurales et vibrationnelles des cristaux ioniques bidimensionnels de type PbFCl,
Thèse de l’université Paris VI
Decker, D.L 1965, Journal of Applied Physics, 36, pp 157
Hammi, Y. 1995 Calcul par élément finis de l’équilibre thermique d’un four à résistance de graphite, Rapport de
Stage de DEA de Mécanique, UPMC-ParisVI.
Le Godec, Y. 1999 Etude du nitrure de bore sous hautes pression et température, Thèse de l’université Paris VII.
Lheureux, D. 2000 Propriétés élastique non linéaires sous pression et diagramme de phase du titanate de strontium,
Thèse de l’université Paris VI.
Study of the neutral products of the acetylene photolysis
between 12 and 16 eV
S.Boyé, A. Campos, S. Douin, D.Gauyacq, A.L Roche et N. Shafizadeh
Laboratoire de Photophysique Moléculaire, Bat 210 Université de Paris-Sud 91405 Orsay
Acetylene is the most abundant molecule, after H2 and CO, in the circumstellar envelopes of
carbonated stars. This molecule, as well as its neutral photodissociation products, play a crucial
role in the carbon chemistry taking place in other astrophysical media such as interstellar clouds
and planetary and cometary atmospheres. Surprisingly, the various photodissociation
mechanisms as well as the photolysis energy dependant branching ratios are not yet well known
or understood. The present work is focused in the photolysis region above the first IP of
acetylene and below the first dissociative ionization threshold, that is, in the region where
ionization only competes with neutral fragment production. By using the high resolution SU5
beam line of Super-ACO, the photolysis of this molecule has been performed between 12 and 16
eV and the dispersed florescence of the fragments has been recorded in the visible region. The
different fragmentation pathways have been characterized and apparition thresholds have been
measured. Fragment internal energy distribution and branching ratios towards the various
fragmentation channels have been determined for a set of photolysis wavelengths. This new data
yields additional information regarding the fragmentation mechanisms and their evolution with
increasing excitation energy. It is expected that these findings will be incorporated into
photochemical models to better understand the carbon chemistry in the above astrophysical
media.
Studying biological tissues using synchrotron infrared microspectroscopy
N. Gross (1) , S. Marull(2) , J.M. Ortega(1) ,T. Marin(1) and P. Dumas(1)
1- LURE Bat 209D, Centre Universitaire Paris Sud, F91898 ORSAY cédex
2- Yves Rocher, 101, Quai du Président Roosevelt, 92 444 Issy les Moulineaux Cedex, France
Point spectroscopy is a valuable tool for biological tissue analysis. However, it suffers from a
particular drawback: the distribution of chemical or histological entities cannot be addressed
throughout the tissue section. To achieve this, the tissue must be either mapped or imaged.
Mapping experiments are currently very popular in IR studies. However, the IR images are of
much lower contrast compared to Raman imaging , due the low brightness of the IR source.
With the use of a synchrotron radiation , the lateral resolution has been improved drastically, and
the resolution becomes diffraction limited.1
Synchrotron IR microscopy can be achieved at LURE, at the MIRAGE beamline 2. We have
studied the composition and distribution profile of several components in skin section. The
achieved resolution allowed us to distinguish clearly between Stratum Corneum to Startum
Granulosum in skin section.
Morever, IR spectroscopy is a very powerful method in determining and imaging the secondary
structure of peptides backbones.
Fig. 1 shows the distribution of lipids in a skin cut. One can clearly see their location, mainly in
in the Stratum Corneum .
Phospholipids
( in
m
)
20
tan
ce
60
Dis
40
20
0
0
Fig. 2 shows the image of the relative concentration of β-sheets over α-helix .
1630cm -1/1655 cm -1
60
40
20
Dis ta n
ce
( in m
)
20
0
These studies opened up new understanding of the composition and structure of biological
tissues, and will be extended towards the study of the penetrating agent behaviour and diagnostic
of disease.
1
L.M. Miller, G.L. Carr, M. Jackson, P. Dumas and G.P. Williams Synchrotron radiation News vol. 13, (5) ( 2000)
31-38.
2
F.Polack, R. Mercier, L.Nahon, C.Armellin, J.P. Marx, M.Tanguy, M.E.Couprie, P.Dumas, SPIE, Eds : P.Dumas
and G.L. Carr Vol.3575 ( 1999) 13.
Photoemission study of Fe-ZnSe(001) interface :
Schottky-barrier height
M. Eddrief a , M. Marangolo a , G.-M. Guichara , V. H. Etgens a , D.H Moscab and F. Sirottic
a
Laboratoire de Minéralogie et de Cristallographie de Paris-CNRS-Universités Paris VI et VII, IPGP,
4 Place Jussieu, 75252 Paris Cédex–France,
b
Departamento de Física- UFPR, Centro Politécnico CP 19091 81531-990 Curitiba PR, Brasil,
c
Laboratoire pour l’Utilisation du Rayonnement Electromagnétique, CNRS -Université
de Paris-Sud Bat. 209-D, 91405 Orsay-France.
Spin injection into a semiconductor is expected to utilize a ferromagnetic material as the
electrical contact. One system of potential interest consists of Fe contacts to a ZnSe
semiconductor. In particular, the Fe/ZnSe bilayer is considered to be promising canditate as spin
aligner in semiconductor based device structures since the wide gap semiconductor ZnSe (Eg =
2.7 eV) could provide the interface resistance (tunnel barrier)1 . Thus it is fundamental to get well
characterized Fe/ZnSe interface, namely to determine the Schottky-barrier height, the interfacial
electronic features and the chemical enviromnent of the species during the Fe contact.
In this work, synchrotron x-ray and ultraviolet radiation based high-resolution
photoemission at LURE-Orsay has been used to study the Fe growth sequentially on ZnSe
surfaces (reconstructed Zn terminated c(2x2) or Se terminated 2x1). The ZnSe samples were
prepared by MBE at LMCP-Jussieu, in a double growth chamber system one for III-V and
another for II-VI semiconductors. GaAs (001) substrates (highly n-doped) were overgrown with
a GaAs buffer layer and ZnSe epilayers. After deposition of a 100Å pseudomorphic ZnSe
epilayer, the surface was stabilized under Zn flux to get a c(2x2)-Zn terminated surface or under
Se flux a (2x1)-Se terminated. These ZnSe surfaces were transferred into a ultrahigh vacuum
transfer box (base pressure ~ 2 10 –10 torr) and transported to an electron spectrometer at the
synchrotron facility (SB7 beam line at SUPERACO-LURE). Also, the ZnSe samples capped
with thick-Se for protection during ambient transfer has been also used. After introduced in the
UHV photoemission set-up, the samples were slowly heated up to 320°C in order to desorb the
Se capping layer and to stabilize the Zn terminated c(2x2) surface. These two transfer and
transport procedures conserves clean ZnSe surfaces without C and O contaminations.
The analysis of the photoemission spectra reveals that the formation of the Fe/ZnSe
interface is essentially abrupt with minimal chemical contact interaction between the topmost
atomic layers of the ZnSe epilayer and the Fe atoms where interacted species are buried in a
limited zone at one or two monolayers near the interface. Also, bulk-like d-band electronic
structure are recovered at 2 ML-Fe coverage. This is in perfect agreement with the previous
XMCD experiment where it has been found that Fe recors its bulk magnetic properties for this
same thickness without magnetic dead layer even below Fe coverage 2 . For 2 ML-thick films, the
Fe-Fermi level position is stabilized at 1.6 eV above the valence-band maximum of the n-type
undoped-ZnSe which corresponds to a Schottky-barrier height value of 1.1 eV 3 .
References :
1
A. Fert, H. Jaffrès, Phys. Rev. B 64, 184420 (2001).
M. Marangolo, F. Gustavsson, M. Eddrief, Ph. Sainctavit, V.H. Etgens, V. Cros, F. Petroff,
J.M. George, P. Bencok, N.B. Brookes, to be published in Phys. Rev. Lett.
3
M. Eddrief, M. Marangolo, S. Corlevi, G.-M. Guichar, V. H. Etgens, R. Mattana, D. H. Mosca
and F. Sirotti, submitted in Appl. Phys. Lett.
2
Bidimensional segregation of mixed Langmuir films of hydrogenated
and fluorinated fatty acids
Marie-Claude Fauré1 , Philippe Fontaine 2 , Nicolas Puff1 , Luc Tamisier1 , Michel Goldmann1&2
(1) Objets Complexes et Interfaces d’Intérêt Biologique (OCIIB), Univ ersité Paris 5, 45, Rue des Saints
Pères, 75270 Paris Cedex 06 ; (2) Laboratoire pour l’Utilisation du Rayonnement Electromagnétique
(LURE), Centre Universitaire Paris Sud, Bât 209D, BP 34, 91 898 Orsay Cedex.
Langmuir monolayers are formed by adsorbing amphiphilic molecules at the air-water interface.
Mixtures of hydrogenated (CH3 (CH2 )n COOH) and fluorinated (CF3 (CH2 )mCOOH) fatty acids
monolayers are efficient systems for the study of two dimensional segregation processes.
Moreover, the understanding of the mixing behaviour of hydrogenated and fluorinated chains is
of prime importance for a vast field of applications[1].
We studied two different mixtures of the perfluorododecanoïc acid (CF3 (CH2 )10COOH) with
stearic acid (CH3 (CH2 )16 COOH) and myristic acid (CH3 (CH2 )12 COOH) (H/F mixtures). The
former hydrogenated fatty acid exhibits at room temperature a phase transition upon
compression of the pure monolayer from a gas phase to an ordered condensed liquid phase. The
latter hydrogenated fatty acid exhibits at room temperature a transition from the 2D gas phase to
a disordered liquid (expanded) phase followed by a transition between the expanded liquid to the
ordered condensed liquid phase.
Although the molecular structures of the two hydrogenated fatty acids are rather similar, the
behaviour of the two mixtures H/F are different. The perfluorododecanoic/stearic acid mixture
exhibits a thermodynamical (Surface pressure vs. Area per molecule isotherms – π-A diagram)
behaviour in favour of a total segregation of the mixture in pure fluorinated and pure
hydrogenated domains. This is confirmed by Grazing Incidence x-ray Diffraction (GIXD)
measurements performed on the D41-B beamline at LURE. Indeed, on the diffraction patterns of
this mixture, two peaks are measured which both respectively correspond to the structures of
pure monolayers of each compound.
The perfluorododecanoic/myristic acid mixture exhibits a completely different and complex
behaviour at any length scales. The evolution of the π-A isotherms with the fraction of
fluorinated molecules is rather complex and is not in favour of a complete segregation of the
mixture. GIXD patterns exhibit a single diffraction peak, which corresponds to the fluorinated
chains structure. However its width is rather large indicating a weak organisation compared to
the pure case. The behaviour of this mixture is rather complex and the experiments (π -A
isotherms and GIXD) do not enable to discriminate between two hypotheses: intimate mixing at
the molecula r level or segregation in small domains.
In order to discriminate between these hypotheses, we performed Grazing Incidence Small Angle
x-ray scattering (GISAXS) at the air water interface on the Troïka II beamline at ESRF. The
results of these experiments indicate an inhomogeneous layer (segregated mixture) and then a
segregation in small domains of the system[2].
References:
[1]
M.P. Krafft, Adv. Drug Delivery Rev. 47, (2001) 209.
[2]
M.C. Fauré, N. Puff, P. Fontaine, L. Tamisier, M. Goldmann, O. Konovalov, in preparation.
Micro-XAS at the Swiss Light Source
A.-M. Flank*, P. Lagarde*, G. Cauchon*, S. Bac*, J.-M. Dubuisson&
* LURE, Bât 209D, BP. 34, 91898 Orsay (France)
SOLEIL, Bât 209H, BP. 34, 91898 Orsay (France)
&
Initiated as a part of the “Option 1” of LURE’s equipment program, this project is a
collaboration between LURE, SOLEIL, and the Swiss Light Source (SLS), which is running
since mid-2001 at a nominal energy of 2.4GeV.
This project is now in its “APD” phase (avant projet détaillé) : this XAS beam line is
planned to cover the 0.8-7 keV energy domain, which corresponds, on an undulator with a period
of about 55 mm, to the best performance in term of brillance of both machines SLS and SOLEIL.
The goal of this beamline is to achieve a spot size on the sample of the order of 1x1 µm2,
keeping the possibility to widely scan the energy. To insure the best focalisation and the
achromaticity, we have chosen a “Kirkpatrick-Baez” focusing optic, with an horizontal prefocalisation by a spherical miror.
The energy range covered by this project extends from 0.8 keV, which is the lower limit of a
double-crystal monochromator, to about 7 keV which corresponds to the cut-off of nickel coated
mirrors. This energy domain presents large overlaps, at both ends, with grating and hard x-rays
beam lines. It will cover the K edges of elements from Ne to Fe, L edges of the 3d and 4d
transition metals and of the first rare earths, M edges of rare earths, actinides and 5d elements.
The use of a x-ray micro beam for spectroscopy (XAS) can be considered from different
points of view.
First of all, one gets access to element-specific micro-cartography experiments, where a
characteristic signature of a given element, like its fluorescence emission, is monitored as a
function of the spatial position of the exciting beam on the sample.. This element imaging, with
spatial resolution at the photon spot scale, is combined to x-ray absorption fine structure
measurements, for an element-specific structural and electronic characterization of the sample.
The expected lateral scales range (depending on the energy range and on the technique used)
from a few thousands of Å to a few microns.
Second, the focusing of the incoming beam can be of a fundamental interest because the
sample environment (in a very general meaning) or the kind of experiment will benefit from a
spot size of microscopic dimensions. New experiments appear then to be possible just because of
a dramatic technical improvement.
And finally, it must be kept in mind that the proposed beam line is intended to be built on
a very brilliant source. Therefore, all experiments that are highly photon consuming, like surface
physics or highly dilute systems, will make profit of the increase of the photon density on the
sample which is expected to be greater that four orders of magnitude at 2 keV, compared to
Super-ACO.
The project presented here has taken the opportunity to be built on a third generation
machine, the Swiss Light Source first. This beamline will be transferred later to SOLEIL.
Oxygen as a surfactant in the growth of (Co, Ni) / Al multilayers
E. Fonda, A. Traverse
Laboratoire pour l’Utilisation du Rayonnement Electromagnétique, CNRS
Normalised Absorption (a.u.)
Al−Ni alloys have many practical applications as anti−oxidation coatings, light heat−
resistant materials and metallisation of microelectronic devices [1,2,3]. In this contest, the
Ni/Al(111) system have been recently studied by our group and the first steps of the interface
formation have been addressed by x−ray absorption spectroscopy [4]. The study has been
extended to the structures and magnetic properties of Ni/Al multilayers prepared by electron−
gun evaporation [5]. Stacks containing Ni layers with a thickness smaller than 3 nm show no
ferromagnetic behaviour, while structural analysis reveals complete Ni/Al mixing. Other
authors, credited to a simple lowering of the Curie
temperature this lack of magnetic moment. A
1.6
metallic Ni fraction is found only for a deposited
layer thickness equal or exceeding 3nm. In the
1.4
making of magnetic multilayers ferromagnet
(a)
(FM)/Al
intermixing is a drawback. FM/Al
(b)
(c)
1.2
Ni foil
intermixing draw to a net loss of magnetic moment
(d)
for thin layers. The use of oxidated Al in the form of
1.0
AlOx or sputtered Al2O3 left some open questions on
the actual effect of post oxidation of deposited
0.8
layers [6,7]. Finally, the effect of oxidation of Al
instead of Al2O3 sputtering showed to improves
layer roughness [8]. We have tested the effect of
0.6
mild oxidation after each layer deposition in (Co,
Ni) /Al multilayers. An exposure at a stream of dry
0.4
air at the pressure of 10−3 mbar for 5’, is sufficient to
produce unmixed Al/Ni stacks without producing Ni
0.2
oxides at thicknesses as low as 1.5 nm. XAS data
suggest that Ni oxide layers formed should be
0.0
reduced by the following Al vapour deposition.
8325
8350
8375
Our work is in quick progress in the
Energy (eV)
characterisation
of the thermal stability of the
(a) Ni 15Å; (b) Ni 30 Å; (c) Ni 60 Å;
−3
produced stacks and in the characterisation of Co/Al
(d) Ni 15 Å post−oxidated at 10 mbar
stacks. Finally, the different effect of Al post−
oxidation versus Al+FM post−oxidation is shown.
[1] P. Hannu, P. Kattelus, and M. A. Nicolet, in Diffusion Phenomena in Thin Films and Microelectronic
Materials, edited by D. Gupta and P. S. Ho (Noyes Publications, Park ridge, NJ, 1988), p. 432.
[2] F. Fitzer and J. Schlichting, in High Temperature Corrosion, edited by R. A. Rapp (National Association of of
Corrosion Engineers, Houston TX, 1983), p.604
[3] N. S. Bornstein, J. Phys. IV Colloque C9 3. Supplement au J. Phys. III 3 (1993) 367
[4] L. Damoc, E. Fonda, P. Le Fevre, A. Traverse, submitted to J. of Appl. Phys. (2002)
[5] E. Fonda, F. Petroff, A. Traverse, to be submitted to J. Appl. Phys.
[6] R. Schad, K. Mayen, J. McCord, D. Allen, D. Yang, M. Tondra, D. Wang, J. of Appl. Phys. 89 (2001) 6659
[7] J. Fujicata, T. Ishi, S. Mori, K. Matsuda, K. Mori, H. Yokota, K. Hayashi, M. Nakada, A. Kamijo, K. Ohashi,
J. of Appl. Phys. 89 (2001) 7558
[8] M. J. Plisch, J. L. Chang, J. Silcox, R. A. Buhrman, Appl. Phys. Lett. 79 (2001) 391
X-ray surface radiolysis : formation of metal-organic interface
Philippe Fontaine 1 , François Muller1&2 , Samy Rémita3 , Michel Goldmann1&2
(1) Laboratoire pour l’Utilisation du Rayonnement Electromagnétique (LURE), Centre, Bât 209D, BP
34, 91 898 Orsay Cedex (2) Objets Complexes et Interfaces d’Intérêt Biologique (OCIIB), Université
Paris 5, 45, Rue des Saints Pères, 75270 Paris Cedex 05 ; (3) Laboratoire de Chimie et de Biochimie
Pharmacologique et Toxicologique (LCBPT), Université René Descartes, 45, Rue des Saints Pères,
75270 Paris Cedex 06
The formation of a Metal – Organic interface is an open question in material science. Its
applications are numerous from colloïds (nano-shells for micro-catalysis), to thin layers (for
microelectronics). In the radiolysis method, the irradiation of an aqueous solution of metal ions
(such as Ag+ ) induces the radiolysis of water in H• and OH• radicals. H• is a strong reductive
agent against metal ions (Ag+) and induces the reduction into metal atoms (Ag) which latter
aggregates. OH• is a strong oxidative agent which is able to oxidize the metal ions and to
counterbalance the reduction. Ethanol is added to the solution to scavenge the OH• radicals[1].
Our original approach consists in applying the radiolysis method to solution of surfactants selfassembled in supramolecular assemblies and metal ions. The aggregation of metal atoms induced
by the radiolysis around the surfactants polar head will create a metalic thin layer around the
supramolecular assembly used as a template.
We explore two geometies. The spherical geometry of surfactants micelles and the planar
geometry of Langmuir monolayers on silver ions solutions. In this system, we shown than the
irradiation by the x-ray beam at grazing incidence of the water surface covered by a Langmuir
film made of behenic acid leads to the formation of a thin silver layer beneath the organic
film[2]. These experiments have been performed on the D41B beamline at LURE. We followed
the formation and studied the structure of the metal layer by two techniques. By measuring the
diffuse scattering of the incident x-ray beam by height fluctuations of the interface, we followed
the transition of the spectrum from a featureless curve corresponding to the organic Langmuir
films to a curve featuring oscillations characteristics of a thin, dense layer at the interface[3]. By
measuring the in-plane diffraction of the x-ray beam, we have recorded the apparition of
diffraction peaks which intensity and width are characteristic of a cristalline, surface oriented
lattice of heavy atoms, which is unambiguously attributed to a silver clusters.
References:
[1]
J. Belloni, M. Mostafavi, H. Remita, J.L. Marignier, M.O. Delcourt, New. J. Chem., (1998) 1239
[2]
F. Muller, P. Fontaine, S. Remita, M. Goldmann, soumis à J. Am. Chem. Soc.
[3]
C. Gourier, J. Daillant, A. Braslau, M. Alba, K. Quinn, D. Luzet, C. Blot, D. Chatenay, G. Grübel, J.-F.
Legrand, and G. Vignaud Phys. Rev. Lett. 78, (1997) 3157.
Étude de la structure locale d’ions aqua d’éléments produits de fission a vie
longue par exafs : pd(ii) complexes
J. Purans1,3, F. David1, B. Fourest1, V.Sladkov1, L. Venault2
1 - Institut de Physique Nucléaire, 91406 Orsay
2 - CEA Valrho, Marcoule, BP 171, 30207 Bagnols
3 - Institute of Solid State Physics University of Latvia, Riga
Les produits de fission à vie longue du combustible nucléaire représentent un enjeu crucial relatif
à la radiotoxicité à long terme des déchets de haute activité. L’impact après stockage sur
l’environnement est, en particulier, un problème de tout premier ordre et une stratégie de
séparation suivie de transmutation ou de séparation, puis conditionnement, est à envisager. Parmi
l’ensemble des produits de fission à vie longue, le sélénium-79, le zirconium-93, le paladium107 et l’étain-126 sont ceux pour lesquels la chimie est la plus mal connue et la nature même des
ions aqua est très controversée. Puisque les éléments considérés existent à l’état naturel, on peut
entreprendre ces recherches en absence de radioactivité.
Pendant l’année 2001, on s’est limité à l’étude du palladium. Les données structurales
(XANES et EXAFS) sur le palladium en solution, sont, à notre connaissance, pratiquement
inexistantes!!! L’ensemble des mesures représente 7 échantillons en solution qui ont été préparés
par voie chimique (IPN) et 1 solide.
Dans le cas du palladium, seul l’état bivalent est stable en milieu acide nitrique. Pd(II) est
donc complexé par les nitrates. La position et l’amplitude des pics dans le XANES ne varient pas
avec la concentration d’acide nitrique. Pour raison électronique (d8), la configuration des
premiers voisins de Pd(II) est plane carrée. Les spectres XANES ont été calculés d’après les
données cristallines de Pd(NO3)2*2H2O par FEFF8.
Les données XANES et EXAFS sur Pd(II), présent en milieu acide nitrique, ont été
enregistrées à température ambiante en transmission.
Nous avons recherché tout d’abord à mettre en évidence :
• la formation des complexes : Pd(NO3)+, Pd(NO3)2, Pd(NO3)3– et Pd(NO3)42• la structure des ions : Pd2+ aqua, Pd(NO3)+, Pd(NO3)2, Pd(NO3)3– et Pd(NO3)42-.
Les résultats de l’analyse EXAFS sont les suivants :
• La position et l’amplitude du premier pic (Pd-O) dans le TF d’EXAFS ne varient pas avec la
concentration d’acide nitrique. L’analyse EXAFS des premiers voisins de Pd(II) en milieu
acide nitrique donne : N(Pd-O)=4 ; R= 2.00±0.02 Å ; DW = 0.003±0.0005 Å2.
• En revanche, l’amplitude du deuxième pic dans le TF d’EXAFS varie fortement avec la
concentration d’acide nitrique. L’analyse EXAFS des deuxièmes voisins de Pd(II) en milieu
acide nitrique donne :
HNO3 10 M
N=4 (NO3) formation des complexes: Pd(NO3)3– et Pd(NO3)42HNO3 6 M et 3M N=2 (NO3) formation du complexe Pd(NO3)2
HNO3 1 M et 2M N=1 (NO3) formation du complexe Pd(NO3)HNO3 0.45 M et HClO4 2M
formation de l’ion aquo du palladium : Pd(H2O)42+
Resonant auger spectrocopy on acrylonitrile multilayers,
comparison with the gas phase
J.-J. Galleta, F. Bournela, S. Kubskya, G. Dufour a, F. Rocheta,b, F. Sirottib, E. Kukkc
a
Laboratoire de Chimie Physique, Université Paris 6, Paris, France.
b
LURE, Centre universitaire Paris-Sud, Orsay, France.
c
Department of Physical Sciences, Oulu University, Oulu, Finland.
We present a resonant Auger spectroscopy study of solid acrylonitrile condensed on a
Si(001) substrate at the N K-edge of the NEXAFS spectra. The three Pi* NEXAFS transitions,
denoted 3a", 13a' and 4a" in the Cs symmetry group of the molecule, are polarized in the
molecular plane (a' symmetry) or perpendicular to it (a" symmetry), the highest energy
transition, 4a", being close to the ionization potential (the term value is about –1 eV).
A strong selectivity with the symmetry of the probed unoccupied orbital is observed for
both participator and spectator channels intensities. When the incidence energy is tuned to the
first peak (3a" transition) we observed strong resonant photoemission channel mainly from the
HOMO, 2a" symmetry, whereas at the 13a', the resonant photoemission channel essentially
concerns orbitals of a' symmetry. At both 3a" and 13a' NEXAFS resonances, intense participator
channels and strong spectator shifts are observed (4.7 and 6.6 eV, respectively), indicative of a
localization of the promoted electron around the core-hole. Departures from a Raman behavior
are also seen and discussed in terms of possible vibronic effects.
At the third NEXAFS resonance (4a"), two spectator Auger contributions are observed at
kinetic energy 1.5 and 4.7 eV above the normal Auger position. Beyond the edge only one Auger
(at 1.5 eV above the normal position) persists. We propose that the promoted electron into the
4a" orbital remains localized around the core hole, however it has a non-zero probability of being
transferred into a more delocalized level.
This study is compared with a resonant Auger spectroscopy study of the acrylonitrile gas
phase. Auger decay peaks are strongly modified as a function of excitation energy, and shifts
from the centroïd position are observed due to the presence of vibrational state. Moreover at the
third NEXAFS resonance 4a", no configuration interaction are observed as in the solid phase
meaning a strong localisation of the promoted electron.
Elastic properties of supported polycrystalline thin films:
an x-ray diffraction study
P. Goudeau, P. Villain, P.-O. Renault, K.F. Badawi
Laboratoire de Métallurgie Physique – UMR 6630 CNRS – Université de Poitiers
SP2MI, Bvd Marie et Pierre Curie, B.P. 30179, F-86962 Futuroscope Chasseneuil Cedex
Thin films deposited on non epitaxial substrates by ion beam sputtering often exhibit large
compressive residual stresses and nanocrystalline structures. Theses features are tightly
controlled by the deposition process (mainly the deposited atom energy) and confer to the films
interesting physical properties. Among the most widely used methods to study thin film
mechanical properties, x-ray diffraction (and in particular the sin2ψ method) is the unique non
destructive and phase selective technique which allows to study both the micro structural and
mechanical state in crystalline samples; the inter planar atomic distance is used as an internal
strain gauge.
However, x-ray diffraction is difficult to use in low dimensional systems because the
diffracted intensities are weak due to the reduced thicknesses and nanocrystalline character of
such materials. These problems may be solved using intense x-ray sources such as synchrotron
radiation (S.R.). In addition to the high flux characteristic of S.R. facilities, the wide wavelength
spectra and the optics (micro beam) which are now available on 3rd generation SR beam lines
only allow to perform specific XRD experiments which are not possible with classical x-ray
sources in laboratories. This communication will focus on the two following research axis:
- In situ tensile testing for elastic constant determination (Beam Lines H10, D. Thiaudière & M.
Gailhanou and DW22, E. Elkaïm): due to the particular microstructure (grain size effect –
multilayers), the thin film elastic constants may differ from the bulk material ones (if there
exist!). When applying in situ strains to the sample, it is then possible to extract elastic
constants from X-ray diffraction data,
- X-ray micro beam for thin film buckling analysis - residual stress mapping (ALS Berkeley,
N. Tamura & H. Padmore): depending on the deposited thickness and substrate nature,
relaxation of the stored elastic energy in the films may lead to thin film delamination. µXRD local stress measurements have been done on the blister shown in fig. 1 with 2x3 µm2
spot size.
Figure 1: AFM image of a Blister presents in a 630 nm
gold film sputter deposited on Si substrate; the in plane
width is around 40 µm and the height of 1.2 µm.
References: Philippe.Goudeau@univ-poitiers.fr
X-ray diffraction from crystals under electric fields. Results on a-quartz
R. Guillot a, P. Allé a, P. Fertey a, N.K. Hansen a, and E. Elkaïm b
a
Laboratoire de Cristallographie et Modélisation de Matériaux Minéraux et Biologiques, CNRS -7036,
Université Henri Poincaré – Nancy I, B.P. 239, 54506 Vandoeuvre-lès-Nancy CEDEX, France. b LURE,
Bât.209D, Centre Universitaire Paris-Sud, B.P. 34 - 91898 Orsay CEDEX, France.
The aim of our work is to analyse using of X-ray diffraction, the correlations between structural
and physical properties of crystals onto which an electric field is applied.
In Nancy we have, based on the ideas of previous work [1,2], build a device using a field
switching technique. It consists of a high voltage supply (Vmax= 5 kV), the electronics for
switching the field (+,0,-,0) at frequencies between 104 and 10-2 Hz, and synchronous counting
on four chains combined with a control for step-scanning the diffraction profiles. By using this
'stroboscopic' technique, it is possible to measure very small changes in the Bragg angles due to
the strain resulting from the converse piezoelectric effect, and also to measure minute changes in
the Bragg intensities due to polarisations of atomic structure and electron density [3].
Measurements were carried out at LURE with the 4-circle diffractometer WDIF-4C on α-quartz.
Quartz is a well-characterised piezo-electric material and perfect crystals are available.
Electrodes were vapour deposited onto the (2-10) extended faces of a crystal plate of dimensions
5 x 5 x 0.52 mm. We have been able to determine the known d11 piezo-electric tensor
coefficients by measuring changes in the Bragg angles as small as 0.0002°. The changes in
Bragg intensities for 26 reflections were also measured. Different models have been investigated
for explaining the origin of piezoelectric effect by a refinement of the modification of an initial
structure by a least squares method. The result of this refinement is a reorientations without any
modification of the tetrahedron Si(2)O 4 which make up chains in direction of the electric field, a
modification of the angles of the second tetrahedron which bind the chains imply a modification
of the bridge angles Si- O-Si(2).
O3
O
Si
O
O_3
O
O3
Si
Si_2
O_2
Electric field
We will continue with a study of the effect of electric fields on the isostructural compounds
AlPO4 and GaPO4 .
[1] A. Paturle, H. Graafsma, H.-S. Sheu, P. Coppens & P. Becker (1991) Phys.Rev.B43,14683-14691.
[2] H. Graafsma, G.W.J.C. Heunen, S. Dahaoui, A. El Haouzi, N.K. Hansen & G. Marnier (1997)
Acta Cryst.B53, 565-567.
[3] R. Guillot, P. Allé, P. Fertey, N. K. Hansen and E. Elkaim (2002) Applied Crystallography. in press.
Characterization of Th1-xUxO2 solid solutions by EXAFS
G. Heisbourg, J. Purans, N. Dacheux, and S. Hubert
Institut de Physique Nucléaire, 91406- Orsay
In the last decade, there has been a renewal of interest in studying the faisability of
thorium based fuel reactors as a potential advanced fuel for Generation IV nuclear energy
systems that can be operated to relatively high burn-ups, and producing less minor actinides than
uranium based fuel. In addition, ThO 2 -UO2 fuels will result in a more stable and insoluble waste
form, very resistant to weapons- material proliferation. Also solid solutions of uranium and
thorium oxide are being developed as fuel for the thermal breeding reactors and high temperature
gas cooled reactors. If ThO 2 -UO2 solid solutions have been often characterized by using XRD,
no any XAFS data on the local structure on solid solutions of this system exists in the literature.
In this study, various compositions of mixed oxides have been prepared through the
coprecipitation of the mixed oxalates from nitrate solutions. Both XRD and EXAFS have been
tested to characterize the structure of the ThO 2 -UO2 solid solutions. The lattice parameters, the
fine atomic structure and the ionic distances of the cubic ThO 2 -UO2 solid solutions are
determined respectively from X-ray powder diffraction and EXAFS.
Experimental x-ray absorption spectra were recorded at the uranium and thorium LIII
edge in the transmission mode at the LURE DCI hot line storage ring on the D44 (XAS4)
beamline. The U-O and Th-O distances obtained varie slightly upon dilution. These values of the
are close to the ones expected from the Vegard’s law but are always smaller than the ones
expected in VCA. On the contrary, the U-U(Th) and Th-Th(U) distances varie strongly upon
dilution and the values are close to the ones expected from the VCA model but are always
smaller than the ones expected by the Vegard’s law. Therefore we conclude that thorium and
uranium ions form solid solution.
The dependences of the Th-O and Th- Th(U) distances from the composition have a break
at x≈0.2 and Th-O distance is almost constant at x≤0.2 and slightly decreases upon dilution.
There are also a few XRD reports where slight deviation from the ideality has been observed.
The values of the Th-Th(U) distance in the comparison with U-U(Th) are closer to the ones
expected from the Vegard’s law.
Photoemission studies of clean Si(100) surface and
of Mn/Si(100)-H interface formation
L. Lechevallier (a), R. Brochier (a), R. Flammini (b) , C.M. Teodorescu (b) ,
O. Heckmann(a)(b) , C. Richter (a),V. Ilakovac (a), V.L. Than (c), A. Taleb-Ibrahimi (b) ,
K. Hricovini (a)(b)
(a) LPMS, Université de Cergy-Pontoise, 95031 Cergy-Pontoise
(b) LURE, Centre universitaire Paris Sud, Bât. 209d, B.P. 34, 91898 Orsay
(c) IEF, Centre Universitaire Paris-Sud, Bât. 220, F-91405 Orsay, France
We have studied clean Si(100)-H surface by core- level photoemission spectroscopy.
Deconvolution of Si 2p spectra recorded with different photon energies enabled us to show the
presence of 4 components on the clean Si(100)-H surface. In addition to the bulk component, we
found 2 surface components lying at higher binding energies that can be attributed to Si- H2
(42meV) and to Si- H (24meV) bonds. Finally, there is a fourth component at lower binding
energy (-16meV), as compared to the bulk one. Its origin still today leads to numerous
discussions and whose behaviour differs from Si- H and Si-H2 components. The second part of
our work concerns the growth of Mn thin layers (0.5 - 8 monolayers) on the Si(100)-H surface.
We show that the reactivity of Mn is inhibited by the presence of Si- H bonds and the growth of
Mn is essentially layer-by layer.
XAS study of Chromium in Cr:Li2MgSiO 4
C. Jousseaume a, F. Ribot b, F. Villainc, A. Kahn-Hararia, D. Viviena
a
Laboratoire de Chimie Appliquée de l’Etat Solide (UMR 7574) – ENSCP
11, rue Pierre et Marie Curie – 75231 Paris Cedex 05 – France.
b
Laboratoire de Chimie de la Matière Condensée (UMR 7574) – Université P. et M. Curie
4, place Jussieu, Tour 54 – 5 ème étage – 75252 Paris Cedex 05, France.
c
Laboratoire de Chimie Inorganique et Matériaux Moléculaires, ESA CNRS 7071
U.P.M.C, 4 place Jussieu, 75252, Paris Cedex 05 – France.
c
LURE, UMR 130,
Université Paris-Sud, 91898 Orsay Cedex – France.
The knowledge of chromium environment is necessary to understand the remarkable optical
properties of CrIV in Li2 MgSiO 4 where the fluorescence lifetime is 10 times greater than for
similar materials like forsterite (Mg2 SiO 4 ) and yttrium aluminium garnet Y3 Al5 O12 (YAG) [1].
The aim of our EXAFS work was to determine the environment of CrIV (d2 ion) in Li2 MgSiO 4
very weakly doped with chromium (~0.05%), and to follow by XANES the oxidation states of
Cr (IV, V, VI) during the different elaboration steps of Cr:Li2 MgSiO 4 . Such a matrix contains
several tetra-coordinated sites, so the determination of chromium location is not straightforward.
Indeed, CrIV should rather substitute for Mg or Li, considering its size, but due to its charge, the
Si site would be more appropriate.
EXAFS and XANES investigations on polycrystalline samples, prepared by solid state
reaction, have allowed to identify a parasitic phase (LiCrO 2 ) which was below X-ray diffraction
sensitivity. This phase, LiCrO 2 even though in small proportion, contained most of the chromium
atoms and prevented from analysing the environment of chromium included in Li2 MgSiO 4 .
Recently, and for the first time in the laboratory, single crystals of Cr:Li2 MgSiO 4 were
obtained by the flux method [2]. EXAFS and XANES indicate, first, that chromium is in fourfold
coordination; second, that the Cr-O bond length, is about 1.68 Å. Studies have also been
performed on Cr:Li2 ZnSiO 4 which exhibits the same structure and same optical behaviour, but
contains second shell neighbours (Zn and Si) that can be differentiated through their
retrodiffusion characteristics, which was not possible with Mg and Si in Li2 MgSiO 4 .
Results tend to indicate that Cr substitute for Si in Li2 MgSiO 4 ; this is consistent with its
characteristics (charge and size). The knowledge of the chromium environment will now allow
us to achieve crystal field calculations.
[1] - K.A. Soubbotin, V.A. Smirnov, S.V. Kovaliov, H.J. Scheel, E.V. Zharikov, Opt. Mater. 13 405-410 (2000).
[2] - C. Jousseaume, A. Kahn-Harari, D. Vivien, J. Derouet, F. Ribot, F. Villain, J. Mat. Chem., accepted for
publication.
Study of amorphization by Alkali-Aggregate Reaction in SiO 2 aggregate by
XANES and X-ray diffraction
J. Verstraete1 , L. Khouchaf1 , D. Bulteel1 , E. Garcia-Diaz1 , R. Cortès2 , A.M Falnk 2 and
M.H. Tuilier3
1-Centre de Recherche de l’Ecole des Mines de Douai, 941, rue Charles Bourseul BP.838 59508
DOUAI- France. (e.mail : khouchaf@ensm-douai.fr).
2) LURE, Bât 209D 91405 ORSAY Cedex France.
3-Laboratoire de Physique et de spectroscopie Electronique, FST, 4, rue des Frères Lumière F-68093 –
Mulhouse France Cedex
The effect of the Alkali- Aggregate Reaction on the structure of the concrete has been largely
studied. Several assumptions are proposed to explain the origins and the mechanisms of this
reaction and its role in the degradation of the concrete.
We have been using a new approach which seems very promising and which consists in
characterising the change of the crystal structure of the SiO 2 aggregate. X-ray diffraction and
XANES spectroscopy have been used. Dien Li et al. showed the interest of the X-ray absorption
XANES to observe the amorphization in compounds containing SiO 2 [1,2] and contributed to the
interpretation of the structures which appear in the Si XANES spectra. Through a recent study
we showed the interest of the X-ray diffraction to study the evolution of the crystal structure of
the flint aggregate during the reaction [3]. We showed that the mode of degradation of the
aggregate and its speed constitue significant parameters to evaluate the structural state of
concrete. In this study we present the evolution of the degradation of the crystal structure of the
flint aggregate by Alkali- Aggregate Reaction attack. These results will be combined with the
results of the NMR and the chemical analysis.
Thanks to Si-K XANES results we have highlighted the amorphization of this aggregate during
the reaction (fig.1). X-ray diffraction enabled us to estimate the percentage of the fraction of the
amorphous aggregate in agreement with the results of the chemical analysis (fig.2). We show
that the degradation of the aggregate during the reaction is more complex than a single
transformation of c-SiO 2 into amorphous silica. A study by EXAFS is in hand to quantify the
local environment of silicon. These data should contribute to understanding the mechanisms of
the Alcali- Aggregate Reaction in the concrete.
fig .1 : XANES spectra of (a) quartz, (b) flint aggregate
after 168 hours of attack by the Alcali-Aggregate
Reaction
fig .2 : Evolution of the rate of the amorphous
fraction according to the duration of the reaction.
[1] DIEN LI et al, « High-Resolution Si K and L2,3 edge XANES of α-quartz and sishtovite », Solid State
Communication, 87, 613-617 (1993).
[2] DIEN LI et al, « X-ray absorption of silicon dioxide (SiO2) polymorphs : The structural characterization of
opal » American Mineralogist, 79, 622-632 (1994).
[3] D. Bulteel, E. Garcia -Diaz, J. Dürr, L. Khouchaf, C.Vernet, J.M. Siwak, « Etude d’un granulat alcali-réactif par
diffraction des rayons X », J.Phys.IV, 10, 513-520 (2000).
Structure and fragmentation dynamics of N 2++ and NO ++ ions
M. Ahmad1 , J. G. Lambourne 1 , P. Lablanquie2 , J.H.D. Eland 3 , R.I. Hall1 and F. Penent 1,
1 DIAM, Université P & M Curie, 75005 Paris, France.
2 LURE, Centre Universitaire Paris-Sud, 91898 Orsay, France.
3 PTCL, Oxford University, Oxford OX1 3QZ, UK
Doubly charged molecular ions or dications can be expected to dissociate rapidly due to the
Coulomb repulsion between the two positively charged ions. However, quasi-stable states can
exist above the dissociation limit because of chemical bonding between electrons at short
internuclear distances. A local potential minimum, deep enough to host vibrational states, can be
present. Thus, depending on the properties of the potential surface, these doubly charged ions
can be either (meta)stable or fragment to lower dissociation limits.
We investigate the structure and the dissociation dynamics of dications through the double
photoionisation processes. Our experimental method uses synchrotron radiation and threshold
photoelectrons coincidence spectroscopy (TPEsCO) combined with ion time-of- flight
spectroscopy. We are thus able to obtain information on the vibrational structure of the different
electronic states and characterize the stability, lifetimes, and dissociation paths of these
vibrational states [1].
This TPEsCO technique has allowed us to observe, for the first time, indirect doublephotoionization below the adiabatic double- ionization threshold for N2 ++ formation. These
below-threshold cation pairs were first observed in ion- ion coincidence experiments on H2 O [2]
and CO [3] and in threshold photoelectron-photoelectron coincidence observations for O2 ++ [4].
Following our initial study of the CO++ dication [1], we have extended our observations to
the N2 ++ and NO++ species. In the case of N2 ++, we observe a sharp transition from metastable
states to rapidly dissociating states, as a function of the dication internal energy. This occurs for
an internal energy of near 2.5 eV indicating the high stability of the lowest states of this
dication. The N2 ++ and NO++ ions are the only ones for which optical data also exists [5,6]). The
states known from fluorescence studies, D1 Σ u+ (v=0) for N2 ++ and B2 Σ + (v=0) for NO++, evolve
to stable states of the dication by fluorescence. We have demonstrated, in each case, that these
processes are in competition with fragmentation. Branching ratios between fluorescence and
fragmentation paths can then be established.
References
[1] F. Penent et al, Phys. Rev. Lett. 81, 3619 (1998)
[2] D. Winkoun, G. Dujardin et al, J. Phys. B 21, 1385 (1988)
[3] P. Lablanquie, et al., Phys. Rev. A 40, 5673 (1989)
[4] P. Bolognesi, et al., Phys. Rev. Lett 82, 5673 (1999)
[5] D.Cossart et al, J.Mol.Spectrosc. 113, 142, (1985)
[6] D.Cossart et al, J.Mol.Spectrosc. 125, 142, (1987)
Autoionizing Neon Resonances Separated From Multiple Ionization Continua
J. G. Lambourne1, P. Lablanquie2, F. Penent1, R.I. Hall1, M. Ahmad1, P. Hammond3
1
DIAM, Université P & M Curie, 75252 Paris Cedex 05, France
LURE, Centre Universitaire Paris-sud, Bâtiment 209D, BP 34, 91898 Orsay, France
3
Department of Physics, University of Western Australia, Crawley, Perth, WA6009, Australia
2
The fluorescent decay of the Ne 2s2p6(2S)np 1Po series of autoionizing states has been observed
previously by Lablanquie et al [1]. The fluorescence of doubly excited resonances converging to
higher thresholds of Ne+ is hidden by the fluorescence of excited ion states. The experiment
presented here uses the time structure of Super ACO, operating in two-packet mode, to distinguish
this prompt fluorescence from the slow secondary fluorescence of long lived singly excited states
(lifetimes of the order of 30ns [2]). The possible excitation and decay processes are as follows
Ne+ + hv (Prompt)
hv + Ne
Ne**
Ne+* + e- (Prompt)
Ne* + hv (Prompt)
Ne (Ground State) + hv (Secondary Fluorescence τ=30ns [2])
NeM (Metastable State) + hv (Low Energy)
The detection system consists of a micro-channel plate Z stack behind two grids, polarized to repel
ions and electrons. Metastable states and photons with energy greater than 10eV were detected.
Signal arriving within a 10ns window, which covered the 500ps incident light pulses, was recorded
separately from signal arriving in the 110ns interval between pulses. The yield of threshold
electrons was also recorded. Figure 1 shows the resulting spectra. As the lifetime of the
Ne+ 2s2p6 2S state is 110ps [3] interference with the 2s2p6 2S continuum is completely removed
from the secondary fluorescence and metastable atom yield.
4 1
3
62
2s2p np Series
5
6
2
2p ( D)3s( D)np Series
Prompt Photons
4
5
6
7 8
7 89
2
Secondary Fluorescence
and Metatstable Atoms
4 3
2
2s 2p ( P)3s( P3/ 2)np1/ 2,3/2 Series
6
7 8 9
2 4 3
2
2s 2p ( P)3s( P1/ 2)np1/ 2 Series
4
6
7 8
Threshold Electrons
62
2s2p S1/ 2 Threshold
2
4 3
2
2s 2p ( P)3s P3/2, 1/2 Thresholds
48
49
50
51
Photon Energy (eV)
52
Figure 1: Prompt photon yield (t<10ns), secondary fluorescence and metastable atom yield
(t>10ns) and threshold electrons.
[1] P. Lablanquie et al, Phys. Rev. Lett. 84, 431 (2000)
[2] D. J. Chornay et al, J. Phys. B, 17, 3173 (1984)
[3] C. T. Johnson and A. E. Kingston, J. Phys. B 20, 5663 (1987)
Quadrupolar transitions evidenced by resonant Auger
J. Danger1,2, P. Le Fèvre1 , H. Magnan1,2, D. Chandesris 1 , J. Jupille3 , S. Bourgeois4 , T. Eickhoff5
and W. Drube5
1
LURE, CNRS-Université Paris Sud, Bât. 209d, BP34, 91898 Orsay cedex, FRANCE
2
SPCSI, CEA Saclay, 91 191 Gif sur Yvette, FRANCE
3
GPS, CNRS-Université Paris VI et VII, 2 place Jussieu, 75251 Paris cedex 05, FRANCE
4
LRRS, CNRS -Université de Bourgogne, BP47870, 21078 Dijon cedes, FRANCE
5
HASYLAB at DESY, Notkestraße 85, 22603 Hamburg, GERMANY
The hamiltonian describing the interaction between a photon and matter can be written to second
order as a sum of electric dipolar and quadrupolar terms [1]. If most of the simple absorption
experiments can be interpreted within the electric dipolar approximation, the introduction of
quadrupolar transitions is necessary for the interpretation of magnetic effects in absorption
measurements. For instance, the magnetism of selected orbitals can be probed by X-ray
Magnetic Circular Dichroism; for experiments at the L2,3 edges of rare earths, quadrupolar
transitions from the 2p levels towards the 4f orbitals (which generally carry most of the magnetic
moment in rare earths compounds) give a signal of the same order of magnitude as the one due
to the dipolar 2p→5d transitions [2]. In Resonant X-ray Magnetic Scattering, the signal due to
quadrupolar transitions is predominant at the L3 -edge of rare earths (2p→4f) [3] or at the K-edge
of transition metals (1s→3d) [4].
For a better understanding of the experimental data obtained from these techniques, it is of key
importance to be able to bring to the fore the occurrence of quadrupolar transitions in absorption
spectra, as well as to quantify their intensities. From absorption spectra, quadrupolar transitions
can only be studied by angular-dependent measurements [5]. Resonant spectroscopies offer a
new opportunity to get more insight into excited states of atom by studying lineshapes and
intensities of decay processes. We show that resonant Auger spectra carry a clear signature of an
additional electron promoted in localized empty states via a quadrupolar transition. In our
measurements on TiO 2 , we were able to determine the relative weight of quadrupolar transitions
at the Ti K-edge, as well as the symetries of the orbitals reached by the photoexcited electron.
References
[1] C. Brouder, J. Phys.: Condens. Matter 2, 701 (1990).
[2] F. Baudelet, Ch. Giorgetti, S. Pizzini, Ch. Brouder, E. Dartyge, A. Fontaine, J. P. Kappler and G. Krill, J.
Electron Spectrosc. Relat. Phenom. 62, 153 (1993); H. Matsuyama, K. Fukui, K. Okada, I. Harada and A. Kotani, J.
Electron Spectrosc. Relat. Phenom. 92, 31 (1998).
[3] K. Dumesnil, C. Dufour, A. Stunault and Ph. Mangin, J. Phys.: Condens. Matter 12, 3091 (2000).
[4] W. Neubeck, C. Vettier, K.-B Lee and F. De Bergevin, Phys. Rev. B 60, R9912 (1999).
[5] G. Dräger, R. Frahm, G. Materlik and O. Brümmer, Phys. Stat. Sol. (b) 146, 287 (1988).
Imaging and time-of-flight resolved coincidence studies of dissociative
photoionization of small molecules
M. Lebech1, J. C. Houver1, R. R. Lucchese2, and D. Dowek1
1 Laboratoire des Collisions Atomiques et Moléculaires, Université Paris-Sud, 91405 Orsay,
France.
2 Department of Chemistry, Texas A&M University, College Station, Texas 77842-3012, USA
Time-of-flight resolved ion-electron coincidence detection and imaging techniques with two delay-line
anode position sensitive detectors (PSD) have been combined to develop the vector correlation method
[1] for the study of dissociative photoionization (DPI) of simple molecules. In DPI of XY molecules,
induced by VUV linearly polarized pulsed synchrotron radiation (P) (Super ACO, LURE)
XY + h?(P) → (XY)** → X+ + Y* + e
X and Y being either atomic or molecular fragments, the vector correlation approach consists in
measuring for each event the Vx + and Ve nascent ion and electron velocity vectors. Ions and electrons
are extracted from the interaction region by a DC uniform electric field, whose magnitude insures a 4p
collection of both particles. For each (X+, e) coincident event the time-of-flight T and impact
coordinates (x, y) on the PSD are measured for both particles, thus providing the (Vx +, Ve) velocity
vectors [2]. Electrostatic lenses have been implemented after the extraction region and allow us to
increase the resolution of the determination of the velocity components [3].
The magnitudes of the Vx + and Ve velocities provide the ion and electron kinetic energy correlation
which identifies the pathway for each process, intermediate state and dissociation limit, and leads to the
branching ratios between different processes.
The complete 3D angular distribution I(?x+, ?e, f e), where ?x+ is the polar angle of Vx + referred to P,
?e and f e are the polar and azimuthal electron emission angles in the molecular frame, is derived from the
spatial analysis of the (Vx +, Ve, P) vector correlation for each process. In particular it gives access to
the I(?e, f e) molecular frame photoelectron angular distributions (MFPADs) for any orientation of the
molecular axis with respect to the polarization [4]. These observables provide original information about
the symmetry of the (XY)** states of the continuum, including shape resonances or autoionizing states,
and of the dynamics of the ionization and fragmentation processes.
Recent results will be presented for DPI of small polyatomic molecules like N2O and CO2 and
compared with related PEPICO studies [5]. The MFPADs for photoionization of N2O into the
N
? 2O+(C 2S+) state will be presented and compared with recent theoretical investigations [6].
[1] A. Lafosse, M. Lebech, J. C. Brenot, P. M. Guyon, O. Jagutzki, L. Spielberger, M. Vervloet, J. C. Houver, and D.
Dowek, Phys. Rev. Lett. 84, 5987 (2000)
[2] A. Lafosse, J. C. Brenot, A. V. Golovin, P. M. Guyon , K. Hoejrup, J. C. Houver, M. Lebech, and D. Dowek, J.
Chem. Phys., 114 6605 (2001)
[3] M. Lebech, J. C. Houver, and D. Dowek, Rev. Sci. Instrum. 73, 1866 (2002)
[4] R. R. Lucchese, A. Lafosse, J. C. Brenot, P. M. Guyon, J. C. Houver, M. Lebech, G. Raseev, and D. Dowek, Phys.
Rev. A 65, 020702 (2002)
[5] E. Kinmond, J.H.D. Eland, and L. Karlsson, Int. J. Mass Spectrom., 185 (1999) 437
[6] M. Lebech, J. C. Houver, R. R. Lucchese, and D. Dowek, submitted to J. Chem. Phys.
Characterization and calibration of a silicon drift detector
Marie-Christine Lépy1, Laurent Ferreux1, Christian Rémond2
1 : Bureau National de Métrologie / Laboratoire National Henri Becquerel
CEA Saclay - 91191 GIF-SUR-YVETTE Cedex
2 : Commissariat à l’Energie Atomique / DCRE DE LDX
B.P.12 - 91680 BRUYÈRES-LE-CHÂTEL
Semiconductor (Si or Ge) detectors are traditionnally used for X-ray spectrometry and analysis ;
however, to attain optimum resolution, they need to be cooled with liquid nitrogen what results
in relatively cumbersome setups, needing frequent filling operations.
In front of these drawbacks, the recently available silicon drift detectors (SDD) a priori presents
interesting characteristics. The peculiarity of such detectors is the extremely low anode
capacitance which is moreover completely independent of the active area. This feature allows
reaching higher energy resolution because the signal is less sensitive to the noise contribution of
the subsequent amplifying electronics. Thus, it can be used without cooling or with a moderate
cooling such as obtained using a thermoelectric cooler (Peltier element). Thus, the detector and
its cooling element are included in a compact module, easy to use and to store.
To derive the actual interest of such detectors for routine uses, the calibration and
characterization of a SDD have been performed at the SuperACO SB3 beamline in the 800 eV –
6 keV energy range. The exit of the monochromating setup is equipped with a proportional
counter (Ar-CH4), with a well-regulated pressure, used as the reference detector for efficiency
calibration [1].
The detector has an active surface of diameter 2,5 cm and is equipped with a 8 µm beryllium
window. The detector resolution (FWHM) is 170 eV à 5.9 keV (it is a "medium" quality
detector, as better quality one can attain resolution of 140 eV).
The efficiency calibration is obtained over the energy range with a mean relative uncertainty of
2 %, and the thickness of the different absorbers (window + anode material) can be deduced. The
detector response function is also studied versus the energy : the spectra are fitted using a
Hypermet function. This shape includes a gaussian peak with an exponential left tail
superimposed over a constant background ; the evolution of the different shape parameters over
the energy range is determined, including the shape change at the silicon K edge.
Using a thin collimator (diameter = 100 µm), the detector active area has also been scanned what
allows to show relatively constant efficiency, but significant degradation in the shape of response
function, even in the detector central part.
Thus, at first sight, the studied SDD presents a satisfying global behaviour, however, when
looking more carefully, the above-mentionned amazing details will require further studies.
Moreover, a major last point is the electronic module « black box » what excludes any
intervention from the user. As the evolution of the peak position versus the energy shows a
unique slope, the one of the peak width exhibits a dramatic change when the background
increases : this is unexpected and should be taken into account for detailed spectra processing.
Reference :
[1] Experimental study of the response of semiconductor detectors to low-energy photons.
M.C. Lépy, J.L. Campbell, J.M. Laborie, J. Plagnard, P. Stemmler and W.J. Teesdale
Nuclear Instruments and Methods in Physic Research A 439 (2000) 239-246.
Relevance of the drying step in the preparation by impregnation
of Zn/SiO 2 supported catalysts
Cyril Chouillet a , Maggy Kermarec a, Hélène Lauron-Pernot a,
Catherine Louis a, Françoise Villain b,c
a) Laboratoire de Réactivité de Surface, UMR 7609 CNRS,
b) Laboratoire de Chimie Inorganique et Matériaux Moléculaires, UMR 7071 CNRS,
Université Pierre et Marie Curie, 4 place Jussieu, F75252 Paris Cedex 05, France
c) Laboratoire pour l'Utilisation du Rayonnement Electromagnétique, Bât 209D
Centre Universitaire - B.P. 34 - 91898 Orsay Cedex
The method of impregnation is the most basic and simple method for the preparation of supported
catalysts. It is usually admitted that after impregnation of an oxide support with a precursor salt followed
by drying and calcination, the corresponding metal oxide is formed onto the support. The results
presented here for the preparation of silica-supported zinc show that the formation of ZnO is not
straightforward and that XAS is a very useful tool to identify the nature of the zinc.
Impregnation of silica with a small volume of solution of zinc nitrate leads to a highly spreaded zinc
nitrate phase. Three types of samples are obtained depending on the temperature of drying :
1. After drying at 25 or 50 °C, the supported zinc phase is amorphous in XRD, but it was clearly
identified as [Zn(H2O)6]2+ by XAS.
2. When the samples are dried between 90 and 150 °C, part of the zinc nitrate transforms into zinc
hydroxynitrate detected by XRD: Zn(OH)(NO3).H2O at 90 and 120 °C and
Zn5(OH)8(NO3)2.2H2O at 150 °C while the other part which is amorphous, was identified thanks to
XAS as a mixture of [Zn(H2O)6]2+ and zinc silicate phase of hemimorphite-type
(Zn4Si2O7(OH).H2O). This indicates that part of the zinc reacts with the silica surface during the
drying step.
3. After drying at 200 °C, the supported zinc phase is also amorphous and XAS showed that most of
the zinc (85 %) is of hemimorphite-type.
After calcination, the Zn/SiO 2 samples which do not contain zinc hydroxynitrate after drying, i.e., the
samples dried at 25, 50 and 200 °C, are amorphous (XRD). XAS shows that they contain only the zinc
silicate phase of hemimorphite-type. In contrast, those which contain zinc hydroxynitrate after drying
(samples dried at 90, 120 and 150 °C), also contain ZnO after calcination, but the ZnO particle size
depend on the drying temperature. Drying at 150 °C leads to large ZnO particles (>100 Å) after
calcination, which are also detected by XRD. Drying at 90 °C leads to small ZnO particles (about 30
Å) after calcination, detectable only by UV-visible and electron microscopy. In both cases, XAS
reveals that the main Zn specie is again the silicate phase of hemimorphite-type.
Caractérisation structurale d'ions par spectroscopie IR :
couplage d'un piège à ions FT-ICR avec le LEL IR
Philippe Maitre
Laboratoire de Chimie Physique, Université de Paris XI, Bâtiment 350
91405 Orsay Cedex, FRANCE
L'étude en phase gazeuse de molécules ou d'agrégats permet une compréhension détaillée de
l'influence de paramètres structuraux ou énergétiques sur les propriétés physico-chimiques de systèmes
complexes. A cet égard, l'étude des ions et des réactions ions-molécule s'avère particulièrement intéressante,
notamment dans les domaines de la chimie organique et organométallique, de la modélisation des milieux
dilués (planétaire, interstellaire, ...) et de la biochimie, domaine en plein essor.
Notre objectif est d'exploiter la source Infra-Rouge intense et accordable délivrée par le laser à
électrons libres de CLIO pour caractériser les ions en phase gazeuse par spectroscopie Infra-Rouge. Nous
utiliserons un piège à ions transportable (MICRA: Mobile ICR Analyser) basé sur l'approche FT-ICR-MS
(Fourier Transform Ion Cyclotron Resonance Mass spectrometry), technique offrant notamment une
excellente résolution en masse et un piégeage efficace sur des temps longs (plusieurs secondes). Le long
temps de piégeage en FT-ICR-MS est essentiel car il offre la possibilité de sonder la structure de l'ion via
des réactions chimiques avec des molécules neutres, des collisions avec des gaz rares ou l'interaction avec
un rayonnement lumineux. En maintenant une faible pression de gaz dans la cellule de réaction, ces
diverses approches permettent la préparation et la sélection d'édifices moléculaires typiquement observés
dans les milieux dilués ainsi que d'intermédiaires réactionnels. La sélection reposant sur le rapport
masse/charge, la caractérisation structurale par spectroscopie infra-rouge serait essentielle.
Des études très récentes montrent que l’utilisation d’un rayonnement IR intense et accordable
permet d’accéder au spectre IR d’ions polyatomiques M+ isolés dans un piège à ions. La densité d'ions étant
faible, la détection de l'absorption n'est pas envisageable. En revanche, la forte intensité du rayonnement IR
délivré par un LEL permet d'induire une fragmentation de l'ion (M+->M’++neutre) via l'absorption
consécutive de plusieurs dizaines de photons IR. L'intensité de la fragmentation de l’ion M+, suivie par
spectrométrie de masse, en fonction de la longueur d’onde IR donne accès au spectre IR. Il semble en effet
établi que la fragmentation de l'ion n'est observée que lorsque la longueur d'onde λ permet l'excitation d'un
mode normal i (vi->vi+1). Le principe d’une telle dissociation induite par plusieurs photons IR de même
longueur d’onde λ repose sur une redistribution très rapide de l’énergie apportée dans le mode normal i
autorisant ainsi plusieurs dizaines de séquences du type (i) excitation du mode normal vi->vi+1, (ii)
redistribution de l’énergie de vibration permettant le retour du mode i au niveau vi.
Cette spectroscopie d'ions paraît particulièrement prometteuse, au point que le groupe Hollandais de
FELIX projette de construire un LEL spécialement dévolu à cette application afin d'insérer la cellule FTICR dans la cavité. En ce qui concerne CLIO, grâce à la transportabilité d'un FT-ICR récemment développé
au LCP, des premiers résultats ont été obtenus en mars 2002 mettant en évidence les potentialités
intéressantes de cette approche pour la caractérisation d'intermédiaires réactionnels organométalliques.
Parmi les autres études envisagées, la caractérisation spectroscopique IR d'ions polyatomiques tiendra une
large place. Il est en effet maintenant bien établi que les bandes IR observées en émission dans le milieu
interstellaire sont dues à des espèces polyaromatiques hydrogénées (PAH). La technique FT-ICR est sans
conteste la plus adaptée pour préparer et piéger des PAH insaturés, c'est-à-dire avec un rapport H/C faible,
éventuellement "chauds" qui semblent les candidats les plus intéressants. Enfin, l'Infra-Rouge offre une
perspective intéressante pour caractériser les interactions faibles dans des agrégats moléculaires et des
macromolécules biologiques. Des expériences de type pompe-sonde pourraient être envisagées afin d'initier
et de caractériser les changements de conformation. A plus court terme, la caractérisation des changements
de conformation de petits peptides induits par un cation métallique est envisagée.
XAS study of the interaction of Pt species with basic sites in zeolites
Pascale Massiani1 , Catherine Pommier1 , Lorenzo Stievano 1 , Françoise Villain2
1
LRS and 2 LCIM2, Université Pierre et Marie Curie, 4 place Jussieu, 75252 Paris Cedex 05, France.
Background
Metal supported on acidic zeolites have been widely characterised in the past (industrial
catalysts for refining and petrochemistry). A recent approach consists in developing basic
properties in zeolites that can be used as such (basic catalysts for fine chemistry) or as new basic
supports of metals (example of the industrial aromatisation Pt/KL catalyst). Our recent
spectroscopic and catalytic studies of Pd/Faujasite1,2 and Pt/BEA3-5 suggest that the metal species
formed during the successive steps of preparation of the catalysts are stabilized by the basic sites,
leading to higher metal dispersions after reduction.
Methodology and Results
In order to better identify the interactions that are involved between the zeolitic basic
framework and the metal species, we have compared by XAS at the LIII edge of Pt, the oxidation
state and environment of Pt in supported zeolite samples in which we have varied the zeolitic
structure (Faujasite or BEA) and the basic character (change of the alkali compensating cation
and/or impregnation by Cs species). Once confirmed the feasibility of the study (ex-situ
experiments), we have undertaken in-situ experiments in which we have followed the state of the
Pt species during thermal treatments (300-500°C) in flowing air then hydrogen.
The more striking results will be presented:
1)
After calcination, the oxidation state of the Pt species is significantly higher in the more
basic zeolitic supports, especially in the Cs-enriched ones in which the presence of highly
dispersed and strongly basic Cs2 O clusters is assumed. Moreover, the EXAFS analysis of
calcined Pt/NaX reveals the presence of Si neighbours in the coordination sphere of Pt2+,
supporting our previous hypothesis obtained from 29 Si MAS NMR1 of a strong interaction
between the Pt2+ cations and the zeolitic framework.
2)
The basicity strongly modifies the reducibility of the calcined Pt species. Thus,
autoreduction by the NH3 ligands of the Pt(NH3 )4 2+ precursor, and reduction at room
temperature in the presence of hydrogen are observed in the less basic samples, whereas on
the more basic ones the temperatures of reduction identified by XANES are higher than
200°C and agree with those previously obtained by TPR (Temperature Programmed
Reduction). The XAS data allow the interpretation of the various peaks shown by TPR
profiles.
Références
1- A. Sauvage, M. Oberson de Souza, M.J. Peltre, P. Massiani, D. Barthomeuf, J. Chem. Soc., Chem. Commun.,
1325 (1996).
2- A. Sauvage, M. Oberson de Souza, P. Massiani, D. Barthomeuf, DGMK Tagungsbericht., Proc. DGMK-Conf.
on "Catalysis on solid acids and bases", Berlin, Germany, march 4-15, 1996, 295-302.
3- F. J. Maldonado, T.Bécue, J. M. Silva, M. F. Ribeiro, P. Massiani and M. Kermarec, J. Catal., 195, 342 (2000).
4- C. Jia, A.P. Antunes, J.M. Silva, M.F. Ribeiro, M. Lavergne, M. Kermarec, P. Massiani, Stud. Surf. Sci. Catal.,
130c, 2993 (2000).
5- T. Becue, F.J. Maldonado-Hodar, A.P. Antunes, J.M. Silva, M.F. Ribeiro, P. Massiani, M. Kermarec, J. Catal.,
181, 244 (1999).
Structure and morphology of thin cobalt films deposited on
vicinal surface Cu(115)
Anne Chaumin-Midoir 1,2, Hélène Magnan1,3, Luc Barbier3 , Patrick Le Fèvre1 ,
Dominique Chandesris1 , and Fabrice Scheurer4
1
LURE, CNRS-Université Paris Sud, Bât. 209d, BP34, 91898 Orsay cedex, FRANCE
2
GPMD, Université Paris XII, 94010 Créteil Cedex, FRANCE
3
SPCSI, CEA Saclay, 91 191 Gif sur Yvette, FRANCE
4
IPCMS, 23 rue du Loess 67037 Strasbourg FRANCE
Thin magnetic films deposited on single-crystal substrates are well known to present magnetic
properties that cannot be found in bulk solids. Surface magneto-optic Kerr measurements on
Co/Cu(115) show no loops below 5 ML and an in-plane uniaxial magnetic anisotropy with an
easy axis parallel to the step edges for thicker films. The origin of this uniaxial anisotropy is
currently believed to arise from missing bonds at the step edges (Néel-type anisotropy) and/or
strain in the film (magnetoelastic anisotropy). In order to determine the origin of these magnetic
properties, we present here a detailed study of morphology and crystallographic structure of thin
Co/Cu(115) films. We used the combination of two techniques: STM and SEXAFS at the Kedge of cobalt. The Cu(115) surface is a vicinal surface of Cu(001): (001) terraces with a width
of 2.5 atomic spacing, separated by steps along [-110]. The clean surface presents wide flat (115)
domains. Co films were evaporated at room temperature in UHV conditions. At the very first
stage of Co growth (0.01 ML), the size of the domains is strongly decreased, showing collective
displacement of Cu atoms. The second stage of growth (between 1 and 3 ML) is characterised by
quite isotropic islands. High-resolution analysis of their height profile along [110] at 1 ML show
that their ascending side is (111) oriented while their descending side is (001) oriented. At 3 ML,
the islands are more regularly organised on the surface with an average size of about 60-70Å.
They are constituted of about four Co layers (115) flat topped with (111) and (001) oriented
sides along [110]. At the third stage of growth (above 5 ML), these islands coalesce but some
deep holes are formed on the surface. We see relatively straight steps aligned with the [-110]
easy magnetic axis. For 8 ML a surface faceting is evidenced with (113) and (001) facet planes
along [110] and a complete vanishing of (111) facets. EXAFS measurements were performed at
77K on thin Co/Cu(115) films evaporated at room temperature for thicknesses above 1ML. For
each sample, we have recorded three spectra using three unequivalent directions of the linear
polarisation of the X-rays ([-110], [110] and [001]) This allows to measure the lattice parameters
in all the crystallographic directions with the same accuracy. For 1 ML, as on the flat Cu(001),
we find a tetragonaly distorted structure with a lattice parameter parallel to the interface equal to
the bulk Cu one [1]. For 3 ML on Cu(115), the structure is completely isotropic with a first
nearest neighbour distance of 2.53 Å (a value between Cu and Co bulk lattice parameters). This
partial relaxation can be correlated with the presence of islands and holes on the surface. For
higher thicknesses (5 and 8 ML), Co adopts a slightly anisotropic face centred tetragonal
structure. The nearest neighbour distance remains the same for the two in-plane directions and is
smaller than in copper. Coming back on the magnetic properties of the films, one concludes that
the step- induced anisotropy is not due to an in-plane magnetoelastic anisotropy but results from
the morphology of the film. A model describing the magnetic anisotropy should take into
account the distribution of missing bonds. This distribution is given by the islands shapes and
faceting effects and it is found to be dependent on the film thickness. It differs notably from the
distribution given by a model assuming no Cu atoms motion and a layer by layer Co growth.
References
[1] O. Heckmann, H. Magnan, P. Le Fèvre, D. Chandesris, and J. J. Rehr, Surf. Sci. 312, 62 (1994).
DRX et EXAFS du Nb dans LiNbO3 fondu
Béatrice Moulin a, Patrick Simon a, Louis Hennet a, Dominique Thiaudière a,b, Marc Gailhanou b
a
C.R.M.H.T. – C.N.R.S., 45071 Orléans Cedex 2
b
LURE , 91405 Orsay Cedex
Fax 02 38 63 81 03 - e-mail : moulin@cnrs-orleans.fr
Le niobate de lithium est très connu pour ses propriétés en optique non linéaire.
Paradoxalement pour un matériau ayant un champ d'applications aussi important, la phase
liquide, au-dessus de Tf=1250°C (pour une stœchiométrie Li/(Li+Nb)=0.485, correspondant à
une fusion congruente), est relativement peu connue, bien que largement utilisée pour
l'élaboration de monocristaux. Cette phase liquide présente néanmoins des caractéristiques
inhabituelles, avec l'existence d'inclusions solides au-dessus de la température de liquidus (de
quelques microns d'après des mesures de diffusion X et neutrons aux petits angles), ainsi qu'un
coefficient de dilatation thermique négatif.1-3
Juste en dessous de la température de fusion, LiNbO3 subit une transition de phase
ferroélectrique – paraélectrique (Tc=1160°C=Tf-100°C). Nous avons entrepris une étude par
spectroscopie de diffusion Raman qui, couplée à un microscope optique, nous a permis
d’observer directement l’apparition de ces inclusions environ 10°C au dessus de la température
de fusion. Cependant, rien ne nous permet d’identifier de façon certaine la composition de ces
inclusions et leur provenance. Un changement d'ordre local dans le liquide, autour du niobium,
pourrait être à l'origine de ce comportement surprenant d'un point de vue thermodynamique, et
induire un caractère métastable pour l'une des phases en présence. Des mesures de diffraction X
et d’EXAFS ont été entreprises sur la ligne H10 du LURE en température afin de vérifier
l’apparition ou non d’une phase solide dans le liquide et afin de suivre l’environnement local du
niobium avec la température. Les résultats que nous avons obtenus sont en accord avec le fait
que les inclusions solides sont du niobate de lithium.
Nous présenterons ici le système utilisé pour les mesures de diffraction X et d’EXAFS à
haute température sur la ligne H10 et les résultats obtenus pour le niobate de lithium.
1.
2.
3.
4.
P. Andonov, S. Kimura et P. Palleau, J. Non-Cryst. Solids 1996, 205-207, 163.
X. Chen, Q. Wang, X. Wu et K. Lu, J. Cryst. Growth 1999, 204, 163.
YS Kuz'minov, Lithium niobate crystals, Cambridge International Science Publishing (1999), et références
incluses
B. Moulin et al, Ferroelectrics, sous presse.
Etude de complexes Tb / antiinflammatoires non-stéroïdiens par EXAFS
I. Nicolis1,2, A. Rieutord3 , V. Hernando4 , E. Curis 1,2, P. Prognon4 , S. Bénazeth1,2
1. Laboratoire de Biomathématiques et Informatique, Faculté de Pharmacie Paris V, 75270 Paris
2. L.U.R.E. / 91898 Orsay
3. Hôpital Robert Debré / 48, boulevard Sérurier / 75019 Paris
4. Laboratoire de Chimie Analytique, Faculté de Pharmacie Paris XI, 92296 Châtenay-Malabry
Les techniques de marquage par luminescence sont depuis les vingt dernières années
de plus en plus utilisées pour l’analyse de composés organiques soit directement soit comme
mode de détection des techniques chromatographiques ou électrophorétiques (1). Dans ce
cadre, la potentialisation de la luminescence du terbium, du samarium, de l’europium ou du
dysprosium par les molécules organiques apparaît une approche séduisante du fait des
caractéristiques spectroscopiques de ces ions métalliques.
Cette potentialisation procède le plus souvent sur le plan moléculaire d’une chélation
du métal par la molécule organique qui joue le rôle de ligand. Parmi les composés d’intérêt
pharmacothérapeutique susceptibles d’être dosé par chélation d’un lanthanide, les dérivés
anthraniliques présentent des structures moléculaires pour lesque lles un transfert d’énergie
avec le terbium a été décrit (2). Cette famille chimique appartient à une classe
pharmacothérapeutique majeure, les anti- inflammatoires non stéroïdiens (AINS). Des études
spectroscopiques en solutions de ces différents complexes organométalliques ont montré que
le transfert d’énergie est variable en fonction des différents ligands et lanthanides utilisés. Ces
observations suggèrent des conformations spatiales différentes pour les complexes formés. La
littérature sur les données structurales de ces derniers est inexistante. Il devenait donc
nécessaire d’étudier de tels complexes en solution.
Pour les AINS de la famille des anthraniliques, les composés sélectionnés sont
l’acide méclofénamique, l’acide niflumique, l’acide tolfénamique, l’acide méfénamique et
l’acide flufénamique. La faible solubilité de ces AINS en milieu aqueux, combinée à la
nécessité de procéder en excès de ligand résulte à des spectres très bruyants, ce qui nous a
conduit à utiliser le méthanol comme solvant. Des spectres ont été enregistrés avec un
détecteur fluorescence multi-éléments à partir des solutions méthanoliques de TbCl3 , en
présence d’acides méclofénamique, niflumique, tolfénamique, et méfénamique mais aussi
d’EDTA et de benzoylacétone, les deux derniers complexes servant comme modèles.
Des changements significatifs au niveau des spectres XANES accompagnent la
complexation. Par ailleurs, une deuxième couche apparaît clairement sur les transformées de
Fourier du signal EXAFS des solutions contenant les AINS ou l’EDTA, compatible avec une
complexation. Les ajustements du signal EXAFS indiquent une diminution du nombre de
coordination en passant de la solution aqueuse à la solution méthanolique, la complexation
étant accompagnée d’un rapprochement des ligands.
Références :
1. Rieutord A, Prognon P, and Mahuzier G. Luminescence par transfert d'énergie : apport des
lanthanides dans la détection de composés d'intérêt pharmaceutique et biologique, en chromatographie liquide et
électrophorèse capillaire. Analusis, (1996), 24, (349-360)
2. Rieutord A, Prognon P, Brion F, and Mahuzier G. Luminescence probes for drugs and xenobiotics:
advantages and limitations. Analyst, (1997), 122, (59R-66R)
A Vacuum-ultaviolet study of fragments formed in the neutral
photodissociation of ethylene
John O’Reilly, Stéphane Douin, Niloufar Shafizadeh, Séverine Boyé, Philippe Bréchignac
and Dolores Gauyacq
Laboratoire de Photophysique Moléculaire, Bat. 210, Université de Paris-Sud, 91405 Orsay, France
The photoabsorption and fluorescence excitation spectra of ethylene (C2H4) have been
simultaneously recorded using monochromated synchrotron radiation in the excitation
wavelength range of 60 to 100 nm. The apparatus employed is adapted for the detection of
fluorescence in the visible region, which was dispersed using a grating monochromator to yield
information on the fragments formed. C2, C2H, CH and H fragments were observed to originate
from the neutral dissociation of states that lie considerably above the first Ionisation Potential
(IP) in energy. Seven dissociation channels have been identified, namely, CH+CH3, 2CH+H2,
C2H+H2+H, C2H+3H, C2H2+2H, C2+2H2, and C2+H2+2H. From the present limited data set a
preliminary determination of the thresholds for these channels has been performed. Upper limits
for the barriers associated with each of these channels are presented and their values discussed in
relation to the dissociation dynamics. Evidence is presented for the existence of the isomer
ethylidene (CHCH3) which has been the subject of considerable theoretical debate but which has
never been experimentally detected.
Metastable metallic phases formed at low temperature by Cs and
Na on GaAs(001)
D. Paget,1 O. E. Tereshchenko,2 J. E. Bonnet,3 P. Chiaradia, 4
F. Wiame, 3 R. Belkhou, 3 A. Taleb- Ibrahimi. 3
1
2
Lab. Phys. Mat. Cond., Ecole Polytechnique, 91128 Palaiseau, France
Institute of Semiconductor Physics, Novosibirsk State University, 630090 Novosibirsk, Russia
3
LURE, bât 209 D, Université Paris-Sud, 91405 Orsay, France
4
Dipartimento di Fisica and INFM, Università di Roma Tor Vergata, 00133 Roma, Italy
We have found, using photoemission spectroscopy at Super Aco ( on the high resolution
SU3 beamline ), that Na and Cs adsorbates on the GaAs(001) surface, kept at 50 K all over the
experiment, form metallic phases at submonolayer coverage (0.5 ML). Above this coverage, all
criteria for metallicity are fulfilled : there appear plasmon satellites in the core level spectra of
the alkali metal ( AM) and of the substrate atoms, as well as a clear Fermi edge in the valence
band spectrum, and the surface photovoltage disappears. These findings are in agreement with
the results of indirect optical investigations (1, 2) on the same systems. The metallic phases are
metastable, since all the manifestations of metallicity irreversibly disappear under cycling to RT.
The analysis of the change of the shape of the core level spectra gives us indications on
the mechanism of the bonding between the atoms of alkali metal (AM) and the GaAs substrate.
Near the transition coverage in the AM core level spectra, there appears a component with a very
narrow width, developing from coverage increase . This component also disappears under
cycling to RT and is characteristic of the metallic phase. With respect to the component at low
coverage, due to insulating AM, the chemical shift of this narrow component is negative for Cs
and positive for Na. These results can be understood using a simple model.
1 D. Paget, B. Kierren, and R. Houdré, J. Vac. Sci. Technol. A16, 2350, (1998).
2 O. E. Tereshchenko, D. V. Daïneka, and D. Paget, Phys. Rev. B64, 085310, (2001).
Raman and X-ray Absorption Spectroscopies for the determination of the
molybdenum symmetry in oxomolybdenum species:
Application to supported oxomolybdate catalysts
G. Plazeneta, b, E. Payena, J. Lynchb
a
Laboratoire de Catalyse de Lille, UPRESA CNRS 8010, Université des Sciences et Technologies de
Lille, Bât. C3, 59655 Villeneuve d’Ascq Cedex, France.
b
Institut Français du Pétrole, 1 & 4 Avenue de Bois-Préau, 92852 Rueil-Malmaison Cedex, France.
The oxidic precursors of hydrodesulfurization (HDS) catalysts are obtained through
incipient wetness impregnation of the support with an ammonium heptamolybdate (AHM)
solution. The understanding of the genesis and the structure of the active phase imposes a precise
determination of that of the preliminary oxidic phase. Numerous studies have dealt with that
issue and considered many kinds of molybdate compounds to describe it. Due to the many
possible reactions at the surface of the support, the possibility of concurrent phases, and the wide
range of possible symmetries of molybdenum, it is of higher interest to be able to distinguish
clearly between the various molybdate compounds by spectroscopic techniques. The two
techniques considered here, i.e. X-ray Absorption Spectroscopy (XAS) and Raman spectroscopy,
are widely used in the characterisation of catalysts. On one hand, Raman spectroscopy, a
vibrational one, can convey molecular informations, whereas XAS, i;e. EXAFS and XANES,
which are able to analyse one specific element, can give respectively structural (neighbouring)
and atomic (symmetry) informations. It is therefore interesting to correlate the results gained by
both techniques, in order to identify structures and/or similarities between reference compounds
and supported species.
In this work, we analysed by means of Raman spectroscopy and Mo K-edge XANES and
EXAFS a wide molybdate panel, with distorted symmetries going from the octahedral to the
tetrahedral one. The fit of the EXAFS spectra enabled us to show the difficulty to determine a
molybdate structure from raw, due to the structural complexities often met. The criteria to sort
the symmetries in Raman spectroscopy and XANES were therefore compared. Based only on the
stretching mode wavenumber of the Mo=Ot (where t stands for terminal oxygen atom), it was
evidenced that Raman spectroscopy cannot lead to a precise classification, due to the low
specificity of this criterion. On the other hand, XANES is much more reliable through the
analysis of the pre-edge peak. A correlation between the Mo=Ot stretching wavenumber and the
XANES intensity pre-edge has been established for the reference compounds which allows us to
define more precisely the structure of the bulk and of alumina-supported oxomolybdates.
Study of an E-glass vitrifiable mixture fusion
Stéphan Pédèche1, Guy Matzen1, Philippe Melin1, Louis Hennet1, 2
Dominique Thiaudière1, 2, Pierre Forian1 and André Douy1
1 - Centre de Recherche sur les Matériaux à Haute Température, 1 D avenue de la recherche scientifique
45071Orléans cedex 2, France
2 - LURE Laboratoire pour l’Utilisation du Rayonnement Electromagnétique, Bat 209D, Université Paris
Sud, 91405 Orsay cedex, France
An approach of the fusion mechanism understanding is presented. The oxide weight composition
is: SiO2 56.7%, CaO 23.4%, Al2O3 13.2%, B2O3 6.3%, SO3 0.4%. The raw materials come
directly from the glass industry. The system is characterised by different techniques:
thermogravimetric analysis, differential scanning calorimetry, dilatometry, electric conductivity,
X-ray diffraction at room temperature and in-situ measurements (a ribbon is heated by Joule
effect), nuclear magnetic resonance, Raman spectroscopy,. The study of the vitrifiable mixture
that has been heated then quenched is compared with an in-situ study using increasing
temperature. These X-ray diffraction experiments can only be done with synchrotron radiation
which offers a very large diffracted intensity even for short acquisition times. Decomposition
reactions of the raw materials occur at first. Then solid-solid reactions take place and lead to the
formation of new solid phases. The first liquid phase appears at 1050°C. Crystals and quartz are
then digested into the liquid phase.
Observation and characterization of the cinnabar phase in
ZnSe at high pressure
J. Pellicer-Porresa,b, A. Seguraa, V. Muñoza, J.P. Itiéc, P. Munschb and A. Polianc
a
Laboratoire de Physique des Milieux Condensés, Université P. et M. Curie - B 77
4 Place Jussieu - F 75252 Paris Cedex 05
b
Institut de Ciència dels Materials, Universitat de València, Dpt. de Física Aplicada, Ed. Investigació,
E-46100 Burjassot (València), Spain
It is well known that ZnO, ZnS and ZnSe transform from either the wurtzite or
zincblende (ZB) structures to rocksalt (RS) under high pressure. The behaviour of ZnTe is richer.
A combined Extended X-ray Absorption Fine Structure (EXAFS) and Energy Dispersive X-Ray
Diffraction (EDXRD) proposed the transformation from zincblende to cinnabar (C) at 9.5
GPa.[1]. Using Angle Dispersive X-Ray Diffraction (ADXRD) authors in Refs.[2] confirmed the
existence of a cinnabar phase in ZnTe, with atomic co-ordinates u(Zn)=0.540 and v(Te)=0.504.
Up to our knowledge, the cinnabar phase has not been found in any other zinc chalcogenide. In
parallel with the experimental research, a number of theoretical investigations on the stability of
the cinnabar structure have been performed. The calculations result in a similar total energy for
the structures involved, so the establishment of the high pressure systematic is very difficult. In
addition, the presence of energy barriers can hinder some phase transitions.
In this paper we present evidences of the existence of the cinnabar structure in ZnSe and
investigate its properties. Our conclusions are derived from an EDXRD experiment carried out
on the ZnSexTe1-x alloy under high pressure.
The samples studied correspond to Se concentrations given by x=1, 0.95,0.9 and 0.8. All
the spectra were taken at room temperature. The samples were grown using the vapor phase
transport method, and then reduced to powder. We used a diamond anvil cell to generate
pressure. A 16:3:1 methanol/ethanol/water mixture was used as pressure transmitting medium.
The pressure was measured using the linear ruby fluorescence scale.
All the samples studied show similar behavior under high pressure. In the upstroke the
samples undergo the well-known ZB-RS phase transformation. In the downstroke a new high
pressure phase appears. The analysis of EDXRD pattern of ZnSe at 10.5 GPa indicates that the
new phase has a hexagonal symmetry with a= 3.785 Å and c=8.844 Å. We propose that the new
phase observed has the cinnabar structure. The cinnabar range of existence diminishes as the Te
content is reduced. In pure ZnSe the new phase coexists with ZB and RS. Without the whole
series of compositions studied it would have been very difficult to measure its lattice parameters
in ZnSe. Some hypothesis concerning the conservation of the first neighbor distances in the RSC and C-ZB transition allow for an estimation of the internal parameters.
References
1. A. San-Miguel, A. Polian, M. Gauthier and J.P. Itié, Phys. Rev. B 48, 8683 (1993).
2. R. J. Nelmes and M.I. MacMahon, N. G. Wright and D.R. Allan, Phys. Rev. Letters 73, 1805 (1994).
High-T coordination of Ln(III) in clay : in situ diffraction and XAFS
D.H. Powella, C. Pitteloud b, H.E. Fischerc, M. Gailhanouc, J. Purans d
a
b
Department of Chemistry, University of Durham, South Road, Durham DH1 3LE, GB.
Insitut de Chime Minérale et Analytique, Université de Lausanne - BCH, CH-1015 Lausanne.
c
Laboratoire LURE, Bat. 209d, Centre Universitaire Paris-Sud, B.P. 34, F-91898 Orsay.
d
Institute of Solid State Physics, Kengaraga Street 8, LV-1063 Riga
Montmorillonite is a clay mineral consisting of regular stacks of negatively charged
aluminosilicate sheets (or layers) separated by charge-balancing interlayer cations. With
increasing humidity, water enters the interlayer region, swelling the clay in a series of steps
known as one-, two- and three- layer hydrates with well-defined interlayer spacings. The
lanthanide(III)-exchanged forms are used in catalysis and pharmaceuticals and are of interest as
models for the interaction of actinide(III) ions with clay used barriers in waste repositories. In
these applications, the question of the coordination geometry of the hydrated ions and whether
they are partially coordinated to the clay surface is of prime importance. Particularly for
understanding catalytic and containment barrier applications, the temperature dependence of this
coordination needs to be taken into account.
The aim of this experiment was to use high temperature in situ XAFS/diffraction to study
simultaneously the effect of progressive dehydration on the coordination of Ln3+ ions
intercala ted in montmorillonite clay and the associated collapse of the clay interlayer spacing.
The samples were thin films (~ 0.2 mm thick) with the clay platelets oriented preferentially
parallel to the film. The mosaic of the clay particles was sufficient to allow observation of the
(001) reflection (interlayer spacing) with the film held at 30o to the incident beam. We were able
to use this arrangement to make the first combined in situ EXAFS and diffraction measurements
in transmission mode on the H10 beamline at temperatures up to 368 o C. In order to investigate
the effect of ionic radius of the interlayer cation, we obtained data for Nd-, Gd- and Lumontmorillonite.
The temperature dependence of the (001) reflection of Lu- montmorillonite in Fig. 1a, and the
associated d-spacings in Fig. 1b, show the decrease in interlayer spacing on dehydration of the
clay at high temperatures. For all three interlayer cations, the spacing changes from that
associated with a ‘two- layer’ hydrate at around ambient temperature to a ‘one- layer’ hydrate at
80 - 100 oC, then decreases progressively at higher temperatures the hydration layer is removed.
The absorption spectra for Lu- montmorillonite in Fig. 1c show a reduction in amplitude of
EXAFS oscillations with temperature corresponding to the decrease of the coordination number
of the interlayer Lu3+. We are therefore able for the first time to link unambiguously the
coordination of the Ln3+ ion with a given interlayer spacing.
-0.4
(b) 16
50000
(a)
(c)
Lu-mont
15
20000
t=185C
t=275C
t=368C
10000
14
100 C
13
12
11
10
3
5
7
2 theta (degrees)
9
-0.8
-1
9
8
0
60 C
-0.6
Gd-mont
log10(I0/I)
30000
16 C
Nd-mont
d(001) / Angstrom
t=23C
t=50C
t=70C
t=100C
t=150C
40000
-1.2
0
100
200
t(°C)
300
400
9.2
9.3
9.4
9.5
9.6
9.7
Energy (keV)
Fig. 1: The temperature variation of (a) the diffraction pattern (001 reflection) of the Lumontmorillonite sample, (b) the interlayer spacing d001 for the three samples, and (c) the raw
absorption spectra for the Lu L3 edge.
Square planar di-N-carboxamido, dithiolato-cobalt(III) complex related to the
Nitrile hydratase metallic site. Addition of axial ligands and oxygenation of
the sulfur atoms : an EXAFS study
K. Provost (1), L. Heinrich (2), Y. Li (2) and A. Michalowicz (1)
(1) Groupe de Physique des Milieux Denses, Université Paris XII, 61 avenue du Général de Gaulle,
94010 Creteil Cedex, France. (2) Laboratoire de Chimie et Biochimie Pharmacologiques et
Toxicologiques, UMR 8601 CNRS, 45 rue des Saints Pères, 75170 PARIS Cedex 06, France
A square planar cobalt(III) complex with a N2S2 di-N-carboxamido di-thiolato tetradentate
ligand mimics the metal core of the Cobalt containing Nitrile hydratases. It forms
hexacoordinated complexes upon addition of ligands like cyanide or isocyanides. The
oxygenation of the equatorial sulfur atoms is possible only in the case of hexacoordinated
complexes, with strongly donors axial ligands (1). The oxygenated species only may present a
catalytic activity.
We performed an EXAFS study of the square planar complex, cyanide and isocyanide
hexacoordinated complexes, thiolato, sulfenato and sulfinato. In the case of the square planar
complex, the EXAFS spectra can be fitted with distances in good agreement with the
crystallographic data (2). The addition of strongly donor axial ligands leads to a huge increase of
the axial distances. This increase induces an enhancement of the multiple scattering signal in the
equatorial plane. When the sulfur atoms are oxygenated, we always observed a Cobalt Sulfur
bond.
(1) L. Heinrich, thèse de l’Université Paris VI.
(2) L. Heinrich, Y. Li, K. Provost, A. Michalowicz, J. Vaissermann, and J-C. Chottard, Inorganica Chemica Acta
318 (2001) 117-126.
Eu2+ and Eu3+ complexes in solid state and solutions
Juris Purans a,b, Gilles Moreau, a Lothar Helm,a and André E. Merbacha
a
Institut de Chimie Moléculaire et Biologique, EPFL - BCH, CH - 1015 Lausanne, Switzerland; b
Institute of Solid State Physics, University of Latvia, LV-1063 Riga
In general the rate of water exchange is significantly faster for Eu2+ complexes than for
corresponding isoelectronic Gd 3+ analogues used as MRI contrast agent. Eu2+ aqua ions
represents the fastest rate of water exchange measured on a non-Jahn- Teller ions, but Eu2+ ion
was one of the few cations for which the hydration structure has not be established by structural
techniques. Here we present a comparative XAFS analysis of Eu2+, Sr2+ and Eu3+, Gd 3+
complexes in solid state and solutions with picometer accuracy, as the dynamic properties of the
analogous complexes should be closely related to the structure of the first coordination sphere.
The XAFS spectra at the Eu2+, Eu3+, Gd 3+ L3 -edges and at the Sr2+ K-edge have been
recorded at LURE. In-situ XANES measurements of white lines amplitudes (Eu2+ and Eu3+
separated about 8 eV) have clearly demonstrated that sealed, oxygen free aqueous, DMF, DMSO
and CH3 CN solutions of Eu2+ ion and Eu2+ poly(aminocarboxylates) are stable in the cell at least
3h (Eu3+ smaller than 1%). In aqueous solutions, a first coordination shell of Eu2+ is formed by
7.2 (3) water molecules at a Eu-O distance of 2.584 (5) Å with a high fluctuation of interatomic
distance of σ2 =0.0138 (5) Å2 that correlate with the fast rate of water exchange. In the nonaqueous solutions (DMF, DMSO and CH3 CN) the coordination number, the distance and DW
factor decrease in comparison with aqueous solutions.
Finally, the local structure of Eu2+ poly(aminocarboxylates) have been probed in both
solid state and aqueous solution, using the XAFS method. More specifically, the method allowed
us to compare these complexes with the isostructural Sr2+ homologues, and with the related Eu3+
and Gd3+ complexes.
[1] G. Moreau, L. Helm, J. Purans, A. E. Merbach, Structural Investigation of the Aqueous Eu 2+ Ion: Comparison
with Sr2+ Using the XAFS Technique, J. Phys.Chem. A 106 (2002) 3034-3043.
[2] G. Moreau, L. Helm, J. Purans, A. E. Merbach XAFS Study of the Eu2+ and Sr2+ Solvation in Non-Aqueous
Solvents: Confrontation with the Aqua Ions, J. Phys.Chem. A, submitted (2002)
X-Ray absorption spectroscopy applied to layered magnetic materials
using the linear polarisation
Mireille Richard-Plouet1 , Murielle Guillot1 , D. Chateigner2-3 , A. Traverse4 and Serge Vilminot1
1.Groupe des Matériaux Inorganiques, IPCMS, UMR 7504, 23 rue du Loess 67037 STRASBOURG
Cedex, 2. LPEC, UMR-CNRS 6087, Université du Maine, 72000 LE MANS , 3. CRISMAT-ISMRA, UMRCNRS 6508, Boulevard Mal Juin, 14050 CAEN Cedex, 4. LURE, Bât. 209A, BP 34, 91898 ORSAY Cedex.
Numerous works are dealing with magnetism of low dimensionnal structures. In order to
understand the exchange mechanisms, a fine structural characterisation of the studied
compounds is necessary to model the magnetic behaviour. Our studies are focused on the
hydrothermal synthesis of nickel silicates obtained from transition metal acetates and a
propylamine modified alkoxysilane (Si(OC2 H5 )3C3 H6NH2 ). Depending on the experimental
conditions, different phases were isolated presenting a transition towards a ferromagnetic
ordering with a ferromagnetic ground state at low temperature, with Ni/Si≈3/2 or an
antiferromagnetic one with Ni/Si≈3/1 [1].
These compounds are bad crystallised finely divided powders. Powder diffraction data are too
poor to allow a structural model refinement, due in particular to the small grain size. The
interlayer distance is close to 21 Å for both compounds.
However, from several spectroscopies (IR and XPS), Ni2+ are known to be located in octahedral
sites sharing edges as in the hydroxide structure (brucite). The absorption coefficients at the Ni K
edge were recorded. Fitting the inverse Fourier transform of the first peak of the Fourier
transform confirms on the one hand that Ni cations are in octahedra with 2.05(2) Å Ni- O
distances, in agreement with the expected value. On the other hand, fitting the second peak
allows us to bring to the fore the existence of 6 second Ni neighbours at 3.11(2) Å together with
2 Si neighbours at 3.24(2) Å et 3.29(2), for the two silicates [2].
Moreover, it was possible to perform orientated self supported films which were also recorded at
the Ni K edge for different incident angles using the polarised character of the synchrotron beam.
The Ni K edge was recorded on the D42 station of the DCI ring in LURE. Such an experiment
was already successfully applied on minerals [3] and gave structural information on
phyllosilicates from which our compounds are derived.
Thus we record the absorption coefficients (χ(α)) for α=70, 60, 50, 35, 20, 0°, where α is the
angle between the incident beam and the normal to the preparation. Experimentally α=90°
spectrum (χ(90°)) can not be performed because the beam would have to be tangent to the film
surface. Nevertheless the latter can be calculated from the other ones by extrapolating χ(α) =
(χ(0°)-χ(90°))cos2 α+χ(90°). The linear relation between χ and cos2 α has been checked, for
every k values. The polarisation effect strongly affect the Fourier transforms of EXAFS
oscillations. This is due to the layered structure of the compound and its texture. In case α=90°,
it is clearly seen that the contribution of the out of plane scattering atoms is lowered. Structural
parameters such as the flattening angle of the NiO 6 octahedra were evaluated : 58 and 60°, which
are expected values. The trioctahedral nature of the layers was confirmed. Lastly, we
demonstrated that the condensation mode of the Si tetrahedra is different from the one observed
in clay structures [4].
1. M. Richard-Plouet, M. Guillot, S. Vilminot and M. Kurmoo, submitted to Chem. Mat.
2. M. Guillot, M. Richard-Plouet and S. Vilminot, J. Mater. Chem. (2002) 12(4); 851-857.
3. A. Manceau, D. Chateigner and W. P. Gates, Phys. Chem. Minerals, (1998) 25; 347-356.
4. M. Richard-Plouet, M. Guillot, D. Chateigner, A. Traverse and S. Vilminot (submitted to J. Coll.
Inter. Sc.)
EXAFS study of the hydrogenation in Ti-Zr-Ni quasicrystals
and approximants
A. Sadoc 1,2, E.H. Majzoub 3, V.T. Huett 4, K.F. Kelton 4
1
LPMS, Université de Cergy-Pontoise, Neuville sur Oise, 95031 Cergy-Pontoise Cedex, France
2
LURE, Centre Universitaire Paris-Sud, BP 34, 91898 Orsay Cedex, France
3
Sandia National Laboratories, 7011 East Avenue, Livermore, CA 95441, USA.
4
Department of Physics, Washington University, St. Louis, MO 63130, USA.
An understanding of the mechanism of hydrogen absorption in metals and intermetallics
is of considerable importance for both technological and scientific reasons. Metal-hydrogen
systems are used in a variety of technological applications, including hydrogen storage materials
and metal-hydride batteries.
Since the discovery of intermetallic alloys with both long-range aperiodic order and
crystallographically forbidden rotational symmetries (1984), a large body of theoretical and
experimental work has been devoted to the study of these materials, known as quasicrystals
(QC’s). Among their physical properties, it has been found that some titanium/zirconium-based
QCs have a larger capacity for hydrogen storage than competing crystalline materials [1]. In
most transition metal alloys, hydrogen atoms prefer to sit in tetrahedrally coordinated sites.
Icosahedral QC’s are also likely dominated by tetrahedral order and thus provide a variety of
sites for interstitial hydrogen.
The effect of hydrogenation on the local structure of Ti-Zr-Ni alloys, quasicrystals and
bcc crystalline approximants, has been studied by means of extended X-ray absorption fine
structure (EXAFS) experiments, performed above the Ti, Zr and Ni K absorption edges, using
the synchrotron radiation. The alloys were loaded to different hydrogen to metal ratios (0, 0.84,
1.2, 1.4, 1.56 and 1.7) in order to follow the evolution of the local structure with hydrogenation.
Drastic changes are observed in the hydrogenated alloys with modifications of distances and
increase of disorder [2].
1
2
Kelton, K.F and Gibbons, P.C., 1997, MRS Bull., 22, 69.
Sadoc, A., Kim, J.Y. and Kelton, K.F., Phil. Mag. A, 79, 2763 (1999) and 81, 2911 (2001).
X-ray reflectivity study of the muscovite-water interface in KCl and
CsCl solutions
M. L. Schlegel1,*, K. L. Nagy1 , P. Fenter2 , N. C. Sturchio 3 , and L. Cheng2
1 Dept. of Geological Sciences, Univ. of Colorado, 399 UCB, Boulder, CO 80309, USA,
2 Environmental Research Division, Argonne National Laboratory, Argonne, IL 60439, USA,
3 Dept. of Earth and Environmental Sciences, Univ. of Illinois at Chicago, Chicago, IL 60607, USA,
* Present affiliation: CEN de Saclay, DEN/DPC/SCPA, Bat 450-BP 11, F-91 191 Gif-sur-Yvette Cedex.
The basal surfaces of micas and most clay minerals carry a structural negative charge resulting
from cation substitution in the bulk that is compensated by sorption of solution cations. While
much is known macroscopically about this sorption mechanism, there is little direct information
on the atomic-scale structure of surface complexes formed by sorbed cations, and its effect on
solid relaxation at the mineral- water interface. In micas, the permanent negative charge results
from substitution in the basal tetrahedral sheets, and it is balanced by interlayer cations that bind
layers together electrostatically. These relatively weak electrostatic bonds can be easily truncated
by cleaving mica, resulting in a large, atomically flat surface whose structural properties can be
determined by X-ray reflectivity. We report the first successful atomic-scale structural analysis
of the interface between muscovite mica and solutions of KCl and CsCl.
ASTM V-1 grade muscovite (KAl3 Si3 O10 (OH)2 ) sheets were freshly cleaved and immersed in 50
mL of 0.01 m KCl or 0.01 m CsCl for ≥ 1 hour to ensure cation saturation of the surface. The
sheets were mounted in a thin film cell [1], and X-ray reflectivity data were collected on the wet
surfaces at the 12-BM station (BESSRC-CAT, Advanced Photon Source, Argonne National
Laboratory) at an X-ray wavelength of 0.6358 Å. Reflected X-ray intensity was measured as a
function of the momentum transfer Q (=(4π/λ)sin(θ)??) by rocking-curve scans through the specular
reflection condition followed by background subtraction and area integration of the rocking-curve
peaks. High-resolution (~1.5-1.0 Å) reflectivity data were modeled using atomistic structural
models that include surface relaxation, cation concentration and position, and water structure.
Best fits of reflectivity data for muscovite in 0.01 m KCl indicated that K+ is located at 1.67 ±
0.06 Å above the oxygen basal plane. This distance is similar to that observed between interlayer
K+ and oxygen basal planes in the mica structure (1.697 Å) [2] and indicates that sorbed K+ is
located in the ditrigonal cavities of muscovite surfaces. Water is also present at the same distance
from the basal planes than K+. Structural relaxation of muscovite was significant to a depth of 20
Å, but relaxation of individual atomic layers was always ≤ 0.05 Å..
The best fit model for the muscovite in 0.01 m CsCl was obtained for Cs+ possibly cosorbed with
water and located at 2.15 ± 0.09 Å above the basal plane oxygens. This distance is larger than
observed between interlayer Cs+ and oxygen basal planes in nanpingite, a Cs mica (1.922 Å) [3], but
substantially smaller than the calculated distance for Cs located above the basal plane of a substituted
tetrahedron (2.58 Å). It is therefore proposed that sorbed Cs+ is located in the ditrigonal cavities of
muscovite surfaces. The relaxation of mica layers in CsCl solutions parallels that observed in KCl
solution, with layer relaxation ≤ 0.07 Å, and relaxation propagating to a depth of 20 Å.
References:
[1]. P. Fenter, H. Teng, P. Geissbühler, et al. Geochim. Cosmochim. Acta 64, 3663-3673 (2000).
[2]. S. Guggenheim, Y.-H. Chang and A.F. Koster Van Groos. Amer. Mineral. 72, 537-550 (1987).
[3]. Y. Ni and J.M. Hughes. Amer. Mineral. 81, 105-110 (1996).
Magnetic coupling in Co/Cu multilayers: field dependent antiferromagnetic
ordering investigated by resonant X-ray scattering
Carlo Spezzani 1 , Piero Torelli 1 , Maurizio Sacchi 1 , Renaud Delaunay 2 , Coryn F. Hague 2
Alessandro Mirone 3 , Raffaella Capelli. 4 , Fahrad Salmassi 5 , Eric M. Gullikson5
and James H. Underwood 5
1
Laboratoire pour l’Utilisation du Rayonnement Electromagnétique, B.P. 34, 91898 Orsay
(France)
2
Laboratoire de Chimie-Physique – Matière et Rayonnement, 11 rue Pierre et Marie Curie,
75005 Paris (France)
3
ISRF, BP.220 38042 Grenoble (France)
4
Consiglio Nazionale delle Ricerche Istituto per lo Studio dei Materiali Nanostrutturati –
Via P. Gobetti 101 - 40129 Bologna
5
Center for X-ray Optics, Ernest Orlando Lawrence Berkeley National Laboratory,University
of California, Berkeley, California 94720, USA
Multilayers comprising ferromagnetic and non- magnetic 3d elements exhibit, for appropriate
choices of materials and thickness, giant magneto-resistance (GMR) [1]. GMR arises from field
induced variations in the interlayer magnetic coupling, associated with spin dependent electron
scattering in the transport process. High/low resistance states are schematically associated to
antiparallel (or antiferromagnetic) and parallel (or ferromagnetic) coupling between adjacent
layers. The high resistance state has been associated, in certain systems, with biquadratic
coupling, giving 90° rotated magnetic domains in adjacent layers [2-3].
Resonant scattering of polarized X-rays (XRMS) can be used to analyze the magnetization
profile, element selectively. Moreover, with an appropriate choice of light polarization and
scattering geometry, both parallel and antiparallel alignment of the magnetic moments can be
probed.
In this work we present the results obtained using XRMS to analyze magnetic ordering in Co/Cu
multilayer. Specular and off-specular scattering was measured as a function of orientation and
direction of the applied magnetic field, and compared to simultaneously recorded resistivity
values.
1 - Baibich et al Phys. Rev. Lett. 61, 2472, (1988)
2 - C. H. Morrows and B. J. Hickey Phys. Rev. B 59, 463, (1998)
3 - T. P. A. Hase et al. Phys. Rev. B 61, 15331, (1999)
IRMA: Instrument pour la Réflectivité Magnétique
Maurizio Sacchi 1 , Carlo Spezzani 1, Renaud Delaunay 2 , Antoine Avila 2
1
Laboratoire pour l’Utilisation du Rayonnement Electromagnétique, B.P. 34, 91898 Orsay
(France).
2
Laboratoire de Chimie-Physique – Matière et Rayonnement, 11 rue Pierre et Marie Curie,
75005 Paris (France).
Resonant scattering of polarized soft X-rays for the investigation of the magnetic properties of
low dimensional systems is a research topic intensively developed at LURE over the last few
years. This technique is capable of structural analysis (X-rays scattering) with chemical
selectivity (photon energy corresponding to an absorption edge) and is sensitive to the system
symmetry (polarized X-rays). For these reasons, it is a useful tool to study nano-structured
material.
The IRMA project, started in 2001, aims at the construction of a new reflectometer capable of
working under UHV conditions. It will make it possible to prepare and measure the samples in
situ, permitting the extension of soft X-rays resonant scattering techniques to surface physics.
At present, we have constructed and tested a UHV compatible two-axes goniometer, including
sample translations.
Tests employing X-rays have been performed on the beamline SU-7 in superACO at LURE
using reference samples. The system works in a base pressure of 2·10-10 . The two axes can rotate
independently with an angular accuracy better than 0.01º.
H10 : A material and high temperature beamline at DCI/LURE
M. Gailhanou, J.-M. Dubuisson, M. Ribbens, L. Roussier, D. Bétaille, C. Créoff,
M. Lemonnier, J. Denoyer, A. Jucha, A. Lena, M. Idir, M. Bessière
Laboratoire pour l'Utilisation du rayonnement Electromagnétique
Centre Universitaire Paris Sud, Bat. 209D, F-91898 Orsay
D. Thiaudière, L. Hennet, C. Landron, P. Melin, Y. Auger, J.-P. Coutures
Centre de Recherches sur les Matériaux à Haute Température
1D, avenue de la Recherche Scientifique, F-45071 Orléans
H10 is a beamline at DCI / LURE which is dedicated to materials sciences and high
temperature studies. This beamline fulfils several purposes :
- the need for a beamline doing diffraction coupled with X-ray absorption spectroscopy
on the same experimental conditions in the 4 – 20 keV energy range.
- the interest of CRMHT (Centre de Recherche sur le Matériaux à Haute Température) to
study structural properties of Oxydes in the molten state (up to 3000° K) using
synchrotron radiation.
- To have a higher flux than the other DCI/LURE bending magnet beamlines to achieve
time resolved XRD experiments or XAS on more diluted systems.
- The optics will be transfered to the future synchrotron SOLEIL
In this poster, we will show a general description of the beamline and we will present
different examples such as DAFS experiments on FeCo alloys or WAXS / EXAFS experiments
at high temperature.
Fe(II)-Fe(III) hydrolysis and complexation with As(III)-As(V)
in the presence of PO4 ions
Thoral, S.*; Rose, J.*; Flank, A. M.**; Garnier, J. M.* and Bottero, J. Y.*
* CEREGE UMR 6635 Europôle Méditerranéen de l'Arbois BP80 13545 Aix-en Provence Cedex 4
** LURE Centre Universitaire Paris Sud 91405 Orsay Cedex
Arsenic (As) concentrations above 10 µg/l in Bangladesh and West Bengal groudwaters
(the Maximum Contamination Level for drinking water ), are found in over 50% of the wells,
placing an estimated 20 million people at risk of developing cancer 1,
The key result obtained so far on field by our teams, sampling wells in a 16 km2 area in
Bangladesh (30 km East of Dacca), is that both initial dissolved As and Fe concentrations in
these waters decrease drastically following oxidation. However phosphate and silicates seem to
inhibite As-Fe complexation during oxidation (unpublished results). It thus appear essential to
better describe these complex As and Fe interactions to develop efficient water treatment
procedures
Adsorption and stability of arsenate, As(V), and arsenite, As(III), on highly reactive
hydrous ferric oxides 2, 3 as well as adsorption of arsenate on Green Rust 4 (mixed Fe(II)-Fe(III)
oxyhydroxides) were already well investigated using X-ray absorption spectroscopy. However,
coprecipitation mechanisms between arsenic and iron have not been well established so far at the
molecular scale. We then performed Fe and As K-edge EXAFS measurements at beam line D42
of DCI in October 2001 for synthetic freeze-dried Fe(III)-As(V)/As(III), Fe(III)-As(V)/As(III)-P
coprecipitations and for Fe(II)-As(V)/As(III) anoxic solutions. The pH values and
concentrations/ratios used describe at best Bangladesh groudwaters conditions (6.5<pH<7.5,
0<As/Fe<1, 0<As+P/Fe<1).
Under both oxidizing and reducing conditions, As(III) has only minor effects on the local
structure of the Fe-P coprecipitates while the use of experimental Fe-As amplitude and phase
shift fonctions for Fe-As(V)-P systems greatly increased the fit quality of the partial EXAFS
spectra corresponding to the second coordination sphere. These preleminary results will allow us
next September at beam line D42 of DCI to study the local evolution of the Fe(II)-As(III) system
during oxidation as the initial reduced state and final oxidized state are now well known.
[1] Smith, A. H. et al. (2000). Contamination of drinking water by As in Bangladesh : a public health emergency.
Bull. World Health Organization, 78(9), 1093-1103.
[2]Manceau, A. (1995). The mechanism of anion adsorption on iron oxides : evidence for the bonding of arsenate
tetraedra on free Fe(O,OH)6 edges. Geochimica and Cosmochimica Acta, 59, 3647-3653.
[3]Raven, K. P.et al (1998). Arsenite and Arsenate adsorption on ferrihydrite : kinetics, equilibrium, and adsorption
envelopes, Environmental Science and Technology, 32, 344-349.
[4]Randall, S. R. et al. (2001). Sorption of As(V) on green rust and lepidocrocite : susrface complexes from EXAFS
spectroscopy. Geochimica and Cosmochimica Acta, 65, 1015-1023.
Polyfunctional tris(oxalato)metalate based magnets :
Structure and Magnetism from X.A.S. and X.M.C.D.
Train Cyrille°*, Pointillart Fabrice°, Villain Françoise°‡, Baudelet François ‡, Giorgetti Christine‡, Cartier
dit Moulin Christophe°‡, Gruselle Michel° and Verdaguer Michel°
°Laboratoire de Chimie Inorganique et Matériaux Moléculaires, Unité CNRS 7071,
Université Pierre et Marie Curie, 4 place Jussieu, Case 42, 75252 Paris Cedex 05, France
‡
LURE, Bât. 209d,Université Paris-Sud, 92405 Orsay Cedex, France
e-mail: train@ccr.jussieu.fr
Molecule based magnets have been widely studied using X-ray absorption spectroscopy (XAS).
Fine structural changes have thus been correlated with changes in the magnetic properties. More recently,
X-ray magnetic circular dichroism (XMCD) has brought a decisive understanding in the local magnetism
of Prussian Blue derivatives [1].
Thank to the richness and the versatility of the oxalate chemistry, it is possible to conceive oxalatebased systems which combine magnetism - at the molecular level or with long-range order - with other
physico-chemical properties. We are exploiting this potentiality to create optically active tris-oxalatometalate based magnets. The tris-oxalato-metalate molecular synthon leads to two-dimensional (2D) or
three-dimensional (3D) anionic networks [M1M2(ox) 3]-/2- (ox = C2O42-, M1,M2 = first transition series metal
ions). The dimensionality depends on the choice of the cationic counterpart [2].
In a first part, we report results about [Ru(bpy) 3][Cu2(ox) 3] (bpy=2,2'-bipyridine). The material
includes a 3D anionic network obtained in its optically active forms from [Cu(H2O)6]2+ and free oxalate
using the strong chiral template effect of enantiomerically pure [Ru(bpy) 3]2+. According to powder X-ray
diffraction (XRD), the environment around the copper is a regular octahedron while XAS reveals a "4+2"
coordination, as shown in [3]. The two complementary sources of information leads to a better
understanding of the exchange coupling in the system.
The second part is devoted to the XMCD study of the optically active magnet [TBA][NiCr(ox) 3]
(TBA = tetrabutylammonium) between 11 and 30 K with magnetic fields ranging between 0 and 2 T, at
the Cr and Ni K-edges. The compound orders magnetically below TC = 16 K. The measurements give a
local confirmation of the nature of the exchange coupling deduced from macroscopic magnetic
measurements. Moreover, the dichroïc signal, under an applied field of 2 T, is multiplied by 3 when the
temperature decreases from 25 K to 11 K, e.g. when going from the paramagnetic phase to the
ferromagnetic one, through the Curie temperature TC. The high coercivity displayed by the material (0.28
T at 2 K) was exploited to measure the dichroïc signal in zero applied field. We observed a remnant signal
divided by 3 compared to the one observed at 2 Teslas. The later experiment is particularly important in
the study of polyfunctional magnets that can include paramagnetic cations embedded in the magnetically
ordered anionic network. The XMCD measurements in these optically active materials represents an
important step towards the observation by X-rays of the so-called magnetochiral dichroism, a weak crosseffect between magnetic and natural circular dichroism [4].
References
[1] (a) C. Cartier dit Moulin, P. Sainctavit, F. Baudelet, E. Dartyge, et al. J. Am. Chem. Soc. 1998, 120, 11347-11352 ; (b)
C. Cartier dit Moulin, F. Villain et al. J. Am. Chem. Soc. 2000, 122, 6653-6658.
[2] (a) L.O. Atovmyan, G.V. Shilov, R.N. Lyuobovskaya, E.I. Zhilyaeva, N.S. Ovanesyan, O.A. Bogdanova, S.I.
Perumova, Russ. J. Coord. Chem. 23 (1997) 640 (b) R. Andrés*, M. Brissard, M. Gruselle, C. Train, J. Vaissermann, B.
Malézieux, J.P. Jamet and M. Verdaguer, Inorg. Chem. 40 (2001) 4633-4640
[3] F. Villain, M. Verdaguer, Y. DromzéeJ. Phys IV France, 1997, 7, Colloque C2-659-660.
[4] G.L.J.A. Rikken, E. Raupach, Nature (London) 390 (1997) 493-494
Structural characterisation of the Ni-Al (111) interface by
Surface X-ray Absorption Spectroscopy
L. Damoc, E. Fonda, P. Le Fevre and A. Traverse
Laboratoire pour l’Utilisation du Rayonnement Electromagnétique,
Bât. 209D, Centre Universitaire,
BP 34, 91898 Orsay Cedex, France
The evolution of the Ni/Al(111) interface has been studied in situ by X-ray absorption
spectroscopy at the Ni- K edge on the DW21 beam line of DCI. Deposited thickness of the Ni
films on Al(111) were 2 monolayers (ML), 5 ML, 12 ML and 30 ML. The aim was to determine
the diffusion length of Ni and the phases that have formed. The structure of Ni/Al(111) mixed
interface have been characterized by XANES and EXAFS. The EXAFS oscillations have been
fitted using the Fefffit code. The XANES features have been interpreted by comparing
experimental spectra and calculations performed with the FEFF 8.1 code on Nix Aly compounds.
We found that Ni diffused spontaneously at room temperature to a depth that we
estimated to be of the order of 11 ML. The first system formed on Al(111) for 2 ML is Al3 Ni2 like instead of AlNi- like as found by V. Shutthanandan et al (1) on Al(110). Between 2 and 11
ML, we identified a AlNi3 phase, in agreement with (1), then pure Ni grows. We propose that the
pure Ni growth observed after deposition of 11 ML is due to the presence of the AlNi3 aluminide
that acts as a diffusion barrier preventing deeper Ni penetration into Al at room temperature. No
presence of a Nix Al (x~2) system as mentioned by Arranz and Palacio (2) was detected.
(1) V. Shutthanandan, Adli A. Saleh, R. J. Smith, Surf. Sci.450 (2000) 204
(2) A. Arranz and C. Palacio, Thin Solid Films, 317 (1998) 55
X-ray Absorption Spectroscopy of a strongly anisotropic bimetallic
Iron-Cobalt Ferromagnetic Double Chain : dehydration and magnetism
Françoise Villain1,2, Christophe Cartier dit Moulin1,2, Michel Verdaguer1 ,
Rodrigue Lescouezec3 , Miguel Julve
1
Laboratoire de Chimie Inorganique et Matériaux Moléculaires, UMR 7071,
Université P. et M. Curie, 4 Place Jussieu, 75252 Paris Cedex 05, France.
2
Laboratoire pour l’Utilisation du Rayonnement Electromagnétique, UMR 130,
Université Paris-Sud, BP 34, 91898 Orsay Cedex, France.
3
Departament de Quimica inorgànica,Facultat de Quimica de la Universitat de València,
Dr Moliner 50, 46100 Burjassot, València, Spain.
e-mail: villain@ccr.jussieu.fr
Using the facilities available at LURE to study in situ chemical reactions and to follow the
sample changes under constraints (temperature and controlled atmosphere), we studied the effect
on
thermal
dehydration
on
the
structure
of
the
double
chain
[FeIII(bipy)(CN)4 ]2 [CoII(H2 O)2 ]•4H2 O, the structure of which has been determined by single
crystal
X-ray
Diffraction
(XRD).
In
the
fully
hydrated
chain
III
II
[Fe (bipy)(CN)4 ]2 [Co (H2 O)2 ]•4H 2O, the cobalt and iron ions are bridged by cyanide ligands,
with two kinds of water molecules: two are linked to the cobalt ion and four are hydration water
molecules. The magnetic coupling between the iron and the cobalt is ferromagnetic. After
cooling in an applied magnetic field, a very slow relaxation of the magnetisation is observed
when the magnetic field is set to zero. The chain appears to be one of the first « linear nanomagnet ». Two rates of relaxation are observed which can be attributed to dehydration or to
species implying a photoinduced electron transfer. XAS studies at the cobalt and iron K edges
(XANES, EXAFS) were performed at different temperatures under nitrogen atmosphere. The
local surrounding of the cobalt(II) and of the iron(III) was carefully established. No change
occurs in the oxidation degrees of the two metallic ions. The data analysis allows to conclude
that the species responsible of the two relaxation rates are the fully hydrated chain and the chain
after loss of the four water molecules of crystallisation.
Co K edge: XANES spectra and modulus of
Fourier transforms of the EXAFS signals of
[FeIII(bipy)(CN)4 ]2 [CoII(H2 O)2 ]•4H2 O recorded
at 25°C, 100°C and after heating at 180°C.
Non-Rigidity of Organometallic Oxides
V. Artero‡, M. Bénard†, P. Gouzerh‡, P. Herson‡, D. Laurencin‡, A. Proust‡, M.-M. Rohmer†, R.
Thouvenot‡, F. Villain‡, ƒ, R. Villanneau‡
‡
Laboratoire de Chimie Inorganique et Matériaux Moléculaires, UPMC, 75252 Paris, France.
Laboratoire de Chimie Quantique, CNRS / Université Louis Pasteur, 67000 Strasbourg, France.
ƒ
Laboratoire d’Utilisation du Rayonnement Electromagnétique, Université Paris-Sud, Orsay, France.
†
Organometallic oxides have been defined as compounds in which an oxometal core is
surrounded by organometallic moieties. Organometallic derivatives of polyoxometalates form a
specific class of organometallic oxides.1,2 They are of interest owing to their ability to provide
discrete analogues of solid-oxide-supported heterogeneous catalysts, to provide new insights into
surface dynamics, to serve as precursors for transition metal nanoclusters and to display
synergetic or bifunctional catalytic activity.
In this poster, we will focus on the dynamic behavior of the organometallic oxides
[M4O16{Ru(arene)}4] ( M = Mo, W) in solution. The cluster [{Ru(p-cym)}4Mo4O16] (p-cym = pC6H4(Me)(i-Pr)) was first reported in 1997 by Süss-Fink et al.3 In the solid-state, this compound
displays the so-called windmill-like structure, which consists in a {Mo4O16}8- cubic core capped
by four [Ru(p-cym)]2+ groups each bound to three oxygen atoms of the {Mo4O16}8- core.
However, its structural characterization in solution (multinuclear NMR, Raman and X-ray
absorption spectroscopies) indicates the presence of two species in equilibrium.4 The possibility
of interconversion is a sign of flexibility and perhaps it could have interesting consequences on
the catalytic activity.
0,15
60 TC + 40 Eol
CHCl3
0,1
k* χ (k)
0,05
0
-0,05
-0,1
-0,15
4
6
8
10
12
14
16
k (Å-1)
350
95
300
250
ppm
200
150
Mo NMR spectrum of
[{Ru(p-cym)}4Mo4O16]
i)
ii)
Structure of
[{Ru(p-cym)}4Mo4O16]
EXAFS signal of the first shell (Mo-On)
of [Mo4O16{Ru(p-cym)}4] in CHCl3
In this poster, we will show how :
the metal atom (Mo vs. W) has a high influence on the equilibrium.
in the case of Mo, the nature of the ligand allowed us to control the equilibrium and the
distribution of the products.
References :
1
P. Gouzerh, A. Proust, 1998, Chem. Rev., 98, 77
2
R. Villanneau, R. Delmont, A. Proust, P. Gouzerh, 2000, Chem. Eur. J., 6, 1184 ; V. Artero, A. Proust, P. Herson,
P. Gouzerh, 2001, Chem. Eur. J., 7, 3901
3
G. Süss-Fink, L. Plasseraud, V. Ferrand, H. Stoeckli-Evans, 1997, Chem. Commun., 1657
4
V. Artero, A. Proust, P. Herson, P. Gouzerh, 2000, Chem. Commun., 883
X-ray diffraction on liquid iron oxides - influence of oxygen partial pressure
on short-range order
G. Wille1* , L. Hennet1,2, C. Landron1,2, J.C. Rifflet1 , F. Millot1 , M. Gailhanou2 , D. Thiaudière1,2
1. CRMHT – CNRS 1D, avenue de la recherche scientifique 45071 Orléans cedex 2.
2. LURE Centre Universitaire Paris Sud F-91898 Orsay Cedex.
* e-mail : wille@cnrs-orleans.fr
This work is a part of the thesis of G. Wille. The goal is to relate thermophysical properties
(density, surface tension) of liquid Iron [1] and Iron oxides to the local environment of Fe in this
liquids. Solid Iron oxides have been extensively studied
using EXAFS [2] and X-ray diffraction. X-ray diffraction
has been performed on H10 using a special system based on
aerodynamic levitation and laser heating, developed for
EXAFS and X-ray diffraction. This method has been
successfully used for neutron and X-ray scattering [3]. The
experimental cell has been developped in order to be
adapted to liquid iron oxides under controlled atmosphere :
the
experimental cell has been closed, an oxygen
2,5
7
d Fe-O (Ä)
6
analyser is used to control oxygen partial
2,3
feo
5
fe3o4 (Fe-O 1)
pressure and a new levitation nozzle has been
2,1
4
fe3o4 (Fe-O 2)
3
designed : the nozzle is generally a ceramic
1,9
fe2o3 (Fe-O 1)
2
fe2o3 (Fe-O 2)
1,7
nozzle. But liquid iron oxides study requires
1
coordinence
1,5
0
oxidant atmosphere and a new metallic nozzle
0
20
40
60
has been developed, in order to avoid nozzle
% (Ar/2.5% H2) mixed with (Ar/3.5% O2)
deterioration and to improve the stability of the
levitated liquid drop. This nozzle has been
x-ray diffraction on liquid iron
successfully used for x-ray diffraction [4] on
liquid iron oxydes at T = 1900 K under different atmospheres obtained by mixing (Ar / 3.5% O2 )
and (Ar / 2.5% H2 ). Results show an increase
of the Fe-O distance with decreasing oxygen
partial pressure corresponding to Fe3 O4 domain
in the solid oxides part of the phase diagram.
Coordinence of Fe is approximately constant.
Complementary experiences have been
performed recently on liquid FeO and Fe3 O4 .
Liquid oxides have been studied by x-ray
diffraction and EXAFS under different
oxidation conditions. It give information on liquid iron oxides in less oxidant conditions and
confirm results obtained from previous experiences.
[1] G. WILLE, F. MILLOT, J.C. RIFFLET - communication at the 6th international workshop on subsecond
thermophysics - to be published in Int. J. Thermophys. (2002)
[2] Z.Y. WU, S. GOTA, F. JOLLET, M. POLLAK, M. GAUTIER-SOYER, C.R. NATOLI - Phys. Rev B vol.
55 n° 4 (01/1997) p. 2570 - 2577
[3] L. HENNET, C. LANDRON, P. BERTHET, J.P. COUTURES, T. JENKINS, C. ALETRU, N. GRAVES Jpn. J. Appl. Phys. Vol. 38 (1999) suppl. 38-1, pp.115-117
[4] S. KRISHNAN, D.L.PRICE - J. Phys. condens. matter vol. 12 (2000) p. R145-R176
List of Participants
ADJOURI Caroline
04 73 40 79 42
04 73 40 72 62
adjouri@lure.u-psud.fr
AHMAD Muthanna
01 44 27 73 66
01 44 27 70 82
muthanna@ccr.jussieu.fr
ALCARAZ Christian
01 64 46 81 85
01 64 46 41 48
Christian.Alcaraz@lure.u-psud.fr
ALONSO Bruno
02 38 25 76 82
02 38 63 81 03
LASMEA
Université Blaise Pascal
24, Avenue des Landais
Clermont Ferrand
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DIAM
Université P&M Curie
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LURE
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CRMHT
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alonso@cnrs-orleans.fr
ASCONE Isabella
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isabella.ascone@lure.u-psud.fr
BARRETT Nicolas
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493084135694
Fritz-Haber-Institut der MPG
Abteilung Oberflächenphysik
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DE 14195 BERLIN
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Bât. 209H
BP 34
91898 ORSAY CEDEX
FRANCE
CRMHT - CNRS
1d avenue de la recherche scientifique
45071 ORLÉANS CEDEX 2
FRANCE
MUNSCH Pascal
01 64 46 88 57
LURE
Centre Universitaire Paris-Sud
Bât. 209 D
01 64 46 41 48
BP 34
munsch@lure.u-psud.fr
91898 ORSAY CEDEX
NICOLIS Ioannis
Biomathématiques et Informatique
01 53 73 97 78
FRANCE
4, av. de l'Observatoire
Faculté de Pharmacie
Université Paris V
nicolis@pharmacie.univ-paris5.fr
OUVRARD Guy
02 40 37 39 21
75006 PARIS
FRANCE
Institut des Matériaux Jean Rouxel
2, rue de la Houssinière
BP 32229
02 40 37 39 95
44322 NANTES CEDEX 3
ouvrard@cnrs-imn.fr
FRANCE
PAGET Daniel
Lab. de Physique de la Matière Condensée
01 69 33 46 52
Ecole Polytechnique
Route de Saclay
01 69 33 30 04
91128 PALAISEAU
daniel.paget@polytechnique.fr
FRANCE
PAYEN Edmond
Lab. de Catalyse Hétérogène et Homogène
03 20 43 49 47
03 20 43 65 61
edmond.payen@univ-lille1.fr
PEDECHE Stéphan
02 38 25 76 82
02 38 63 81 03
pedeche@cnrs-orleans.fr
Univ. des Sciences et Technologies de Lille
Bât. C3
BP 48
59655 LILLE
FRANCE
CRMHT
1D, av de la recherche scientifique
45071 ORLÉANS CEDEX 2
FRANCE
PELLICER-PORRES Julio
01 44 27 44 70
01 44 27 44 69
jp@pmc.jussieu.fr
PENENT Francis
01 44 27 43 10
01 44 27 70 82
penent@ccr.jussieu.fr
PORCHERON Lucette
01 64 46 80 10
01 64 46 41 48
lucette.porcheron@lure.u-psud.fr
PRIETO Pilar
34913974924
Physique Milieux Condenses
Université P. et M. Curie
B 77, Tour 13-14, 2ème étage
4 Place Jussieu
75252 PARIS
FRANCE
DIAM
Université P. et M. Curie
T12 B75
4, place Jussieu
75252 PARIS CEDEX 05
FRANCE
LURE
Centre Universitaire Paris-Sud
Bât. 209D
BP 34
91898 ORSAY CEDEX
FRANCE
Dpto Fisica Aplicada C-XII
Universidad Autonoma de Madrid
Cantoblanco 401
34913973969
ES 28049 MADRID
pilar.pietro@uam.es
SPAIN
PROVOST Karine
GPMD
01 45 17 65 84
01 45 17 15 79
provost@univ-paris12.fr
PURANS juris
3712251691
U.F.R. Sciences et Technologie
Université Paris XII-Val de Marne
61 avenue du Général de Gaulle
94010 CRÉTEIL CEDEX
FRANCE
Institut of Solids State Physics
University of Latvia
Kengarara Strasse 8
3717112583
LV 1063 RIGA
xas@latnet.lv
LATVIA
RAMOS Aline
551932874520
551932874632
Lab Nacional de Luz Sincrotron
CP6192
13084-971 CAMPINAS -SP
BRASIL
aramos@lnls.br
RAOUX Denis
01 64 46 88 80
SOLEIL
Centre Universitaire Paris-Sud
Bât. 209H
01 64 46 88 61
BP 34
denis.raoux@soleil.u-psud.fr
91898 ORSAY CEDEX
REMOND Christian
CEA
01 69 26 40 02
FRANCE
DCRE/SDE
BP 12
91680 BRUYÈRES-LE-CHATEL
christian.remond@cea.fr
FRANCE
RIBOT François
Chimie de la Matière Condensée
01 44 27 41 35
01 44 27 47 69
fri@ccr.jussieu.fr
ROULLIAY Marc
01 64 46 88 07
01 64 46 41 48
marc.roulliay@lure.u-psud.fr
ROUZIERE Stephan
01 64 64 82 50
Université Pierre et Marie Curie
Case 174
4, place Jussieu
75252 PARIS
FRANCE
LURE
Centre Universitaire Paris-Sud
Bât. 209D
BP 34
91898 ORSAY CEDEX
FRANCE
LURE
Centre Universitaire Paris-Sud
Bât. 209 A
91898 ORSAY
stephan.rouziere@lure.u-psud.fr
FRANCE
ROY Pascale
01 64 46 82 89
LURE
Centre Universitaire Paris-Sud
Bât. 209D
01 64 46 41 48
BP 34
pascale.roy@lure.u-psud.fr
91898 ORSAY
SADOC Anne
LPMS
01 34 25 70 28
01 34 25 70 71
Anne.Sadoc@lpms.u-cergy.fr
SAUVAGE Michèle
01 64 46 80 18
01 64 46 88 61
michele.sauvage@soleil.u-psud.fr
SCHLEGEL Michel
01 69 08 93 84
01 69 08 32 42
michel.schlegel@cea.fr
SHAFIZADEH Niloufar
01 69 15 75 02
FRANCE
Université de Cergy-Pontoise
5 Mail Gay-Lussac
Neuville
95031 CERGY-PONTOISE
FRANCE
SOLEIL
Centre Universitaire Paris-Sud
Bât. 209H
BP 34
91898 ORSAY CEDEX
FRANCE
Lab. for the study of radioelements in their environment
CEN Saclay
DEN/DPC/SCPA/LCRE
Bât 450 - BP 11
91191 GIF SUR YVETTE CEDEX
FRANCE
Photophysique moléculaire
Université Paris-Sud
Bât. 210
01 69 15 67 77
91405 ORSAY
niloufar.Shafizadeh@ppm-u.psud.fr
FRANCE
SINGLETON Lawrence
IMM
496131990142
496131990205
singleton@imm.mainz.de
Carl-Zeiss strass,18-20
DE 55129 MAINZ
GERMANY
SIROTTI Fausto
01 64 46 80 94
LURE
Centre Universitaire Paris-Sud
Bât. 209D
01 64 46 41 48
BP 34
fausto.sirotti@lure.u-psud.fr
91898 ORSAY CEDEX
TADJEDDINE Abderrahmane
LURE
01 64 46 80 02
01 64 46 41 48
abderrahmane.tadjeddine@lure.u-psud.fr
TALEB-IBRAHIMI Amina
01 64 46 82 87
01 64 46 41 48
amina.taleb@lure.u-psud.fr
THIAUDIÈRE Dominique
01 64 46 80 72
01 64 46 41 48
thiaudiere@lure.u-psud.fr
THISSEN Roland
01 69 15 75 73
FRANCE
Centre Universitaire Paris-Sud
Bât. 209D
BP 34
91898 ORSAY CEDEX
FRANCE
LURE
Centre Universitaire Paris-Sud
Bât. 209D
BP 34
91898 ORSAY CEDEX
FRANCE
LURE - CRMHT
Centre Universitaire Paris-Sud
Bât. 209D
BP 34
91898 ORSAY
FRANCE
Laboratoire de Chimie physique
Centre Universitaire Paris-Sud
Bât 350
01 69 15 30 53
91405 ORSAY
roland.thissen@lcp.u-psud.fr
FRANCE
TOLAS Pascal
Lab. Chimie Physique Mat.
TORELLI Piero
01 64 46 80 94
LURE
Centre Universitaire Paris-Sud
Bât. 209D
01 64 46 41 48
BP 34
piero.torelli@lure.u-psud.fr
91898 ORSAY CEDEX
TOUGARD Pierre
Lab. de Modélisation et d’Ingénierie des Protéines
01 69 15 71 41
FRANCE
Centre Universitaire Paris-Sud
Bât. 432
01 69 85 37 15
91405 ORSAY CEDEX
pierre.tougard@mip.u-psud.fr
FRANCE
TRAIN Cyrille
CIM2
01 44 27 30 59
UPMC
4 Place Jussieu - Case 42
01 44 27 38 41
75252 PARIS CEDEX 05
train@ccr.jussieu.fr
FRANCE
TRAVERSE Agnès
LURE
01 64 46 88 26
Centre Universitaire Paris-Sud
Bât 209A
BP 34
agnes.traverse@lure.u-psud.fr
VACHETTE Patrice
01 64 46 88 55
01 64 46 41 48
patrice.vachette@lure.u-psud.fr
VERSTRAETE Johan
03 27 71 23 19
03 27 71 29 18
verstraete@ensm-douai.fr
91898 ORSAY CEDEX
FRANCE
LURE
Centre Universitaire Paris-Sud
Bât. 209D
BP 34
91898 ORSAY
FRANCE
Laboratoire Analyse Physique
Ecole des Mines de Douai
Rue Charles Bourseul
BP 838
59508 DOUAI
FRANCE
VIDAL Franck
01 64 46 81 22
LURE
Centre Universitaire Paris-Sud
Bât. 209D
01 64 46 41 48
BP 34
Franck.Vidal@lure.u-psud.fr
91898 ORSAY CEDEX
VILLANNEAU Richard
Chimie Inorganique et Matériaux Moléculaires
01 44 27 55 53
01 44 27 38 41
villane@ccr.jussieu.fr
WIGLEY Dale B.
442072693930
442072693803
d.wigley@cancer.org.uk
WILLE Guillaume
02 38 25 56 87
02 38 63 81 03
FRANCE
Université Pierre et Marie Curie
case 42 Bat. F pièce 429bis
4, Place Jussieu
75252 PARIS CEDEX 05
FRANCE
Molecular Enzymology Laboratory
London Research Institute
Clare Hall Laboratories
Cancer Research UK
Herts EN6 3LD BLANCHE LANE, SOUTH MIMMS
UK
CRMHT
1d avenue de la recherche scientifique
45071 ORLÉANS CEDEX 2
FRANCE
wille@cnrs-orleans.fr
WUILLEUMIER François
01 69 15 65 36
LIXAM
Université Paris Sud
Bât. 350
01 69 15 58 11
91405 ORSAY
francois.wuilleumier@lixam.U-psud.fr
FRANCE
ZOBELLI Alberto
LURE
01 64 46 80 90
01 64 46 41 48
alberto.zobelli@lure.u-psud.fr
Centre Universitaire Paris-Sud
Bât. 209D
BP 34
91898 ORSAY CEDEX
FRANCE
LURE
Laboratoire pour l’Utilisation du Rayonnement Electromagnétique
Bât. 209D – BP 34 – 91898 Orsay cedex (France)
Tél. : 33 01 64 46 80 00