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Headlines 2007

19-12-2007
H. Gilles, S. Girard, M. Laroche, A. Belarouci CIMAP, Caen

The SNOM (Scanning Near-field Optical Microscopy) allows to reach a spatial resolution well below the wavelength of the light used. Indeed, thanks to the "near-field" illumination (when the distance between the object and the source is much less than the wavelength) it becomes possible to avoid the diffraction inherent to every optical system. Measurement of the evanescent field at the back side of a total-reflection interface allows obtaining a SNOM image with a resolution well below one micrometer.

13-11-2007

Clusters consists in a set of several up to million atoms in condensed phase with nanometric finite size. The investigation of their properties as the function of their increasing size is sometimes presented as one way to build a macroscopic condensed world from a gas. This often appears to be too simplistic, because the static and dynamic behavior of clusters has often no equivalence at the macroscopic scale, as they are controlled by their high specific surface and their finite size. These concerns the physical chemistry of the mesoscopic world, as illustrated by the recent experimental study driven by the "Reaction dynamics" group of DRECAM/SPAM-Laboratoire Francis Perrin in collaboration with a theoretician team from Paris VI University.

23-03-2007
V. Brenner, F. Piuzzi, I. Dimicoli, B. Tardivel, and M. Mons

One of the great mysteries of life is its lack of symmetry at the molecular scale. Many biological molecules, like amino acids, exist a priori in two asymmetrical forms, "right” and “left”. Such molecules are referred to as “chiral” . Like the two hands, these forms cannot be superimposed but are mirror images of each other (Fig.). However, in living organisms, proteins are exclusively built up from “left” amino acids. This selection of only one form remains one of the great scientific enigmas, which physicists, chemists and biologists try to solve.

Proteins are extremely long chains of amino acids. Each amino acid is added by formation of a peptide bound (CONH) and release of a water molecule, leaving a residue attached to the chain. Within the cells, the proteins thus formed are folded and their function depends not only on their sequence but also on their conformation. This makes the studies of the fundamental mechanisms of protein folding of strong interest.
By studying both experimentally and theoretically the folding of simple peptides, made of two amino acids, researchers from the "Service des Photons, Atomes et Molécules” of CEA-Saclay have obtained new results documenting the issue of chirality of the living world.

16-03-2007
J.M. Mestdagh, L. Poisson, I. Fischer, P. D’Oliveira
Service des Photons, Atomes et Molécules DRECAM/SPAM

The very new laser of the "Plateforme Laser Femtoseconde Accordable, PLFA" began to be installed last year within the Service of Photons Atoms and Molecules (SPAM). It belongs to the infrastructure SLIC, member of the European network LASERLAB-EUROPE and is thus accessible to European scientists. It was designed according to several bets: high repetition rate (1 Khz), strong pulse energy (up to 13mJ, at 800nm), broad accordability (500-750nm) and ultra-fast pulses (<35 fs = 35 10-15 s).

The requirement of a wide wavelength range, even difficult to realize, is necessary to allow decisive progress in physico-chemistry of fast reactions. The requirements in pulse duration were chosen to probe efficiently the dynamics of reactions.

Research in that field began within DRECAM at the beginning of the 90's. They led to a revolution in physico-chemistry: the duration of the energy flow within organic or bio-organic molecules often scales within the sub-picosecond time range. This was at variance with the models usually used of redistribution of energy by coupling between electronic excitation and vibration.

The PLFA project is essential to offer a more complete approach: it allows at the same time energy studies, by adjusting the quantity of energy deposited in the system, selectivity by the accordability of the source and time studies at the femtosecond scale.

19-12-2007
H. Gilles, S. Girard, M. Laroche, A. Belarouci CIMAP, Caen

The SNOM (Scanning Near-field Optical Microscopy) allows to reach a spatial resolution well below the wavelength of the light used. Indeed, thanks to the "near-field" illumination (when the distance between the object and the source is much less than the wavelength) it becomes possible to avoid the diffraction inherent to every optical system. Measurement of the evanescent field at the back side of a total-reflection interface allows obtaining a SNOM image with a resolution well below one micrometer.

13-11-2007

Clusters consists in a set of several up to million atoms in condensed phase with nanometric finite size. The investigation of their properties as the function of their increasing size is sometimes presented as one way to build a macroscopic condensed world from a gas. This often appears to be too simplistic, because the static and dynamic behavior of clusters has often no equivalence at the macroscopic scale, as they are controlled by their high specific surface and their finite size. These concerns the physical chemistry of the mesoscopic world, as illustrated by the recent experimental study driven by the "Reaction dynamics" group of DRECAM/SPAM-Laboratoire Francis Perrin in collaboration with a theoretician team from Paris VI University.

21-09-2007
Vincent Mévellec, Sébastien Roussel, Guy Deniau, Serge Palacin

Polymer grafting on surfaces conducting electricity is one major topic of the activities of the "Laboratoire de Chimie des Surfaces et Interfaces (LCSI)" directed by Serge Palacin. Many patents deposited on the electro-grafting (eG©) process contributed to the creation 5 years ago of the first start-up resulting from the Science of Matter Division (CEA/DSM): Alchimer. Beyond the different existing processes for the chemimal fonctionalisation of surfaces, a new step is crossed with the introduction of a new process: Pegas.

Pegas (Procédé d’Enduction Généralisé Actif de Surfaces) allows the grafting in only one stage every standard polymer on any surfaces, conducting or not of electricity avoiding the electrochemical process used until now. In that way, it is possible to functionalize materials as varied as glass, diamond, Teflon, carbon nanotubes but also all the types of metals (gold, steel titanium, iron, zinc, copper etc…). The polymers are grafted in a covalent way on the surfaces and present properties of chemical resistance and conformity equivalent to those obtained by electro-grafting (eG©).

27-06-2007

Researchers at the Institute of Electronics, Microelectronics and Nanotechnologie (IEMN / CNRS – Universités Lille 1 and Valenciennes, Institut supérieur de l’électronique et du numérique-ISEN) and  the Solid-state Physics Division at the French Atomic Energy Agency (CEA), have succeeded in making transistors from carbon nanotubes on a silicon substrate. The transistors, which are mainly used as automatic switches, can reach cutoff frequencies of 30 GHz [1]which improves by a factor of 4 the previous record obtained by the same teams in August 2006. This result opens up new prospects for mainstream applications which require high operating frequencies.

08-06-2007
Nuclear magnetic resonance (NMR) is an indispensable technique for studying matter. It can be applied to medical imaging (MRI) to obtain 2D and 3D images of the human body. While it opens the door to a wealth of physicochemical information by harnessing the fundamental properties of matter, NMR remains a technique with poor sensitivity, making it very difficult to use on small quantities of solid or heterogeneous material. A group of scientists from the CEA research department dedicated to condensed matter, atoms and molecules (DRECAM) is pushing back this limit by using miniaturised mobile detectors to capture the NMR signal with high resolution and a 10-fold increase in sensitivity for sample volumes of a few hundred nanolitres.

To increase in sensitivity on small samples, it is necessary to approach as much as possible the detector (coils surrounding the sample). So, the difficulty to obtain a spectrum high resolution seems insurmountable since it would be necessary to place the sample in a micro-capillary tube and then spun at several thousand revolutions per second in a stable and reproducible way inside a micro-detector (coil) with an interior diameter of a few hundred microns. To meet this challenge, the CEA team (D. Sakellariou, G. LeGoff and J.-F. Jacquinot) came up with an innovative solution by spinning the micro-detector (coil) and sample in one piece, with power to the detector supplied via induction from an exterior coil, which also enabled the (wireless) transmission of the desired signal. The whole system spins at thousands of revolutions per second, and probably constitutes the world's fastest set of rotating antennas.

13-04-2007
P. Viswanath, J. Daillant, L. Belloni, M. Alba, DRECAM/SCM – Service de Chimie Moléculaire, S. Mora (LCVN, Montpellier) et O. Konovalov (ESRF).

When a salt like NaCl is dissolved in water, sodium and chlorine separate in ionic form Na+ and Cl-, become surrounded by water molecules and disperse. This deeply modifies the nature of the solvent which becomes for example, a good electricity conductor. At the surface, the distribution of the ions remains however poorly known, although many "contact" properties depend on it.

Thus, why the surface stress of water decreases with HCl whereas it increases with NaCl? Why KCl is twice more effective than NaCl to crystallize the lysozyme [1] ? Questions of this type, which illustrate the ionic specificity, abound in biology, science of the environment and the atmosphere, sciences of materials, physicochemistry… These effects, which some were described by Hofmeister in 1888 [2], are still not fully explained today. Up to now, only empirical laws were given from macroscopic observations. The difficulty holds from that these effects are primarily due to very short range (below 1 nanometer) strong couplings between the ions and the solvent molecules, and from the lack of measurements of ionic profiles at the interfaces.

11-04-2007
S. Petit, F. Moussa, M. Hennion et S. Pailhès (DRECAM/LLB CEA-Saclay)
L. Pinsard-Godard, Laboratoire de Chimie du Solide, Paris XI
A. Ivanov, ILL, BP 156 F-38042 Grenoble

Multi-ferroïcs are exceptional materials whose fundamental state is both magnetic and ferro-electric [1]. Moreover, in such materials, magnetism and ferroelectricity maintains close links: as for example the manganese oxide YMnO3 [2], can see its magnetization modified by the action of an electric field, or its electric polarization by the action of a magnetic field (magnetoelectric effect). Muli-ferroïcity is a complex problem in physics of condensed matter; it also represents an important stake for the applications, and for example for “technologies for the information and health” developed at the CEA (development of new concepts of memorizing the information or spin electronics).

The last research on these materials tends to show that the coupling between magnetism and ferro-electricity occurs via important deformations of the crystal lattice. It is known for example that in the case of the compound YMnO3, the transition (TN = 72K) towards the magnetic phase (and thus multi-ferroïc) is the seat of magnetostrictive effects that reveals the strong coupling between atomic displacements, magnetic ferroelectricity and moments.

29-03-2007
VKS collaboration (CEA-CNRS-ENS Lyon and Paris), CEA contact: Francois Daviaud

Over the geological ages, the Earth has undergone several erratic reversals of its magnetic field. The sun’s magnetic field is reversed regularly every 22 years according to its cycle. These magnetic dynamics, which are still shrouded in mystery, play a role in our planet’s exposure to cosmic rays.

The joint VKS experiment1  (CEA2, CNRS3,4, the Ecole Normale Supérieure in Lyon3 and the Ecole Normale Supérieure in Paris4) has, for the very first time, been able to observe magnetic field reversals in laboratory conditions thanks to a highly turbulent flow of liquid sodium. The experiments should help scientists to understand more about cosmic magnetic field reversals. The results are published in Europhysics Letters, Volume 77, March 2007.

 The Earth’s magnetic field is created by highly disordered movements that churn up the liquid iron core at the center of the Earth: this is known as the “dynamo” effect. One of its most astonishing characteristics, revealed thanks to paleomagnetic research, is that reversal of the magnetic poles is totally random. They remain close to the Earth’s geographic poles and flip between north and south about once every 100,000 years or so, although longer periods have been found between reversals. On average, these reversals last for a few thousand years.

 The cause and timescale of such reversals, together with the geometry of the magnetic field during a reversal remain the subject of much debate. The consequences may be considerable: during a reversal, the magnetosphere that protects the Earth from solar and cosmic radiation is significantly weakened. Life on Earth, and human life in particular, has survived this kind of situation in the past (the last reversal occurred 700,000 years ago), but it would severely interfere with our modern communications systems (satellites and networks, etc.).

28-03-2007
M.-A. Dubois1, L. H. Emmons2, L. Cournac3, P. Chatelet4, N. C. A. Pitman5, V. Vilca5, & L.-F. del Aguila6

1CEA Saclay, DSM/DRECAM/Service de Physique de l ’Etat Condensé, L ’Orme des Merisiers, 91191 Gif sur Yvette, France
2Department of Zoology NHB 390 MRC 108, Smithsonian Institution, P.O.Box 37012,Washington, DC 20013-7012 USA
3CEA Cadarache, DSV/DEVM/Laboratoire d ’Ecophysiologie de la Photosynthèse, 13108 Saint Paul Lez Durance Cedex, France
4CNRS/URA 1183,Muséum National d ’Histoire Naturelle,
4 avenue du Petit Château,91800 Brunoy, France
5Asociación para la Conservación de la Cuenca Amazonía,
Calle Cuzco 499, Puerto Maldonado, Madre de Dios, Perú
6Fundación Amigos de la Naturaleza, Santa Cruz de la Sierra, Bolivia

23-03-2007
V. Brenner, F. Piuzzi, I. Dimicoli, B. Tardivel, and M. Mons

One of the great mysteries of life is its lack of symmetry at the molecular scale. Many biological molecules, like amino acids, exist a priori in two asymmetrical forms, "right” and “left”. Such molecules are referred to as “chiral” . Like the two hands, these forms cannot be superimposed but are mirror images of each other (Fig.). However, in living organisms, proteins are exclusively built up from “left” amino acids. This selection of only one form remains one of the great scientific enigmas, which physicists, chemists and biologists try to solve.

Proteins are extremely long chains of amino acids. Each amino acid is added by formation of a peptide bound (CONH) and release of a water molecule, leaving a residue attached to the chain. Within the cells, the proteins thus formed are folded and their function depends not only on their sequence but also on their conformation. This makes the studies of the fundamental mechanisms of protein folding of strong interest.
By studying both experimentally and theoretically the folding of simple peptides, made of two amino acids, researchers from the "Service des Photons, Atomes et Molécules” of CEA-Saclay have obtained new results documenting the issue of chirality of the living world.

16-03-2007
J.M. Mestdagh, L. Poisson, I. Fischer, P. D’Oliveira
Service des Photons, Atomes et Molécules DRECAM/SPAM

The very new laser of the "Plateforme Laser Femtoseconde Accordable, PLFA" began to be installed last year within the Service of Photons Atoms and Molecules (SPAM). It belongs to the infrastructure SLIC, member of the European network LASERLAB-EUROPE and is thus accessible to European scientists. It was designed according to several bets: high repetition rate (1 Khz), strong pulse energy (up to 13mJ, at 800nm), broad accordability (500-750nm) and ultra-fast pulses (<35 fs = 35 10-15 s).

The requirement of a wide wavelength range, even difficult to realize, is necessary to allow decisive progress in physico-chemistry of fast reactions. The requirements in pulse duration were chosen to probe efficiently the dynamics of reactions.

Research in that field began within DRECAM at the beginning of the 90's. They led to a revolution in physico-chemistry: the duration of the energy flow within organic or bio-organic molecules often scales within the sub-picosecond time range. This was at variance with the models usually used of redistribution of energy by coupling between electronic excitation and vibration.

The PLFA project is essential to offer a more complete approach: it allows at the same time energy studies, by adjusting the quantity of energy deposited in the system, selectivity by the accordability of the source and time studies at the femtosecond scale.

07-02-2007

M. Roger1, D.J.P Morris2, D.A. Tennant3,4, M.J. Gutmann5, J.P. Goff2, J.-U. Hoffmann3, R. Feyerherm3, E. Dudzik3, D. Prabhakaran6, A.T. Boothroyd6, N. Shannon7, B. Lake3,4 & P.P. Deen8.

1Service de Physique de l’Etat Condensé (CNRS/MIPPU/URA 2464), DSM/DRECAM/SPEC, CEA Saclay, P.C. 135, F-91191 Gif sur Yvette, France.
2Dept. of Physics, University of Liverpool, Oliver Lodge Laboratory, Liverpool L69 7ZE, UK.
3Hahn-Meitner Institute, Glienicker Strasse 100, Berlin D-14109 Germany.
4Institute für Festkörperphysik, Technische Universität Berlin, Hardenbergstrasse 36, Berlin D-10623 Germany,
5ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 OQX, UK.
6Clarendon Laboratory, Parks Road, Oxford OX1 3PU, UK.
7H.H Wills Physics Laboratory, University of Bristol, Bristol BS8 1TL, UK.
8European Synchrotron Radiation Facility, BP 220, F-38043 Grenoble Cedex, France.

27-01-2007
A. Chiffaudel, F. Daviaud, B. Dubrulle, C. Gasquet, R. Monchaux, V. Padilla, avec la participation de L. Marié et F. Ravelet, DSM/DRECAM/SPEC
Collaboration VKS : CEA – ENS Lyon – ENS Paris -

Many research teams aim at understanding of the origin and behavior of the magnetic field of planets and stars. The VKS1 collaboration (gathering researchers at CEA, CNRS, Ecoles normales supérieures in Lyon and Paris) has succeeded in generating a magnetic field from a highly turbulent liquid sodium flow in a laboratory experiment. Although the extreme conditions specific to astrophysical and geophysical media are out of reach in the laboratory, the observed magnetic field shares remarkable similarities with cosmic fields. Their observations are reported in the January 26th issue of Physical Review Letters (see also the "Physical review Focus").

Visit the WEB site of the GIT DRECAM/SPEC !

03-01-2007

Samples from the spatial mission Stardust have been analysed by a team of the Pierre Süe Laboratory in Saclay (CEA-DSM/DRECAM et CNRS-Chimie). The technique used, nuclear reactions induced by a microbeam, allows an absolute measurement of the concentration in constitutive elements in the collected samples. The very first results for the samples of dust issued from the Wild2 comet show a great heterogeneity and variability of the collected grains. These results are published in the journal "Science". The objective is to better understand the formation of comets at the very beginning of the solar system.
(The CEA-CNRS press release -|- The highlight of the DRECAM Department).

21-09-2007
Vincent Mévellec, Sébastien Roussel, Guy Deniau, Serge Palacin

Polymer grafting on surfaces conducting electricity is one major topic of the activities of the "Laboratoire de Chimie des Surfaces et Interfaces (LCSI)" directed by Serge Palacin. Many patents deposited on the electro-grafting (eG©) process contributed to the creation 5 years ago of the first start-up resulting from the Science of Matter Division (CEA/DSM): Alchimer. Beyond the different existing processes for the chemimal fonctionalisation of surfaces, a new step is crossed with the introduction of a new process: Pegas.

Pegas (Procédé d’Enduction Généralisé Actif de Surfaces) allows the grafting in only one stage every standard polymer on any surfaces, conducting or not of electricity avoiding the electrochemical process used until now. In that way, it is possible to functionalize materials as varied as glass, diamond, Teflon, carbon nanotubes but also all the types of metals (gold, steel titanium, iron, zinc, copper etc…). The polymers are grafted in a covalent way on the surfaces and present properties of chemical resistance and conformity equivalent to those obtained by electro-grafting (eG©).

11-04-2007
S. Petit, F. Moussa, M. Hennion et S. Pailhès (DRECAM/LLB CEA-Saclay)
L. Pinsard-Godard, Laboratoire de Chimie du Solide, Paris XI
A. Ivanov, ILL, BP 156 F-38042 Grenoble

Multi-ferroïcs are exceptional materials whose fundamental state is both magnetic and ferro-electric [1]. Moreover, in such materials, magnetism and ferroelectricity maintains close links: as for example the manganese oxide YMnO3 [2], can see its magnetization modified by the action of an electric field, or its electric polarization by the action of a magnetic field (magnetoelectric effect). Muli-ferroïcity is a complex problem in physics of condensed matter; it also represents an important stake for the applications, and for example for “technologies for the information and health” developed at the CEA (development of new concepts of memorizing the information or spin electronics).

The last research on these materials tends to show that the coupling between magnetism and ferro-electricity occurs via important deformations of the crystal lattice. It is known for example that in the case of the compound YMnO3, the transition (TN = 72K) towards the magnetic phase (and thus multi-ferroïc) is the seat of magnetostrictive effects that reveals the strong coupling between atomic displacements, magnetic ferroelectricity and moments.

13-11-2007

Clusters consists in a set of several up to million atoms in condensed phase with nanometric finite size. The investigation of their properties as the function of their increasing size is sometimes presented as one way to build a macroscopic condensed world from a gas. This often appears to be too simplistic, because the static and dynamic behavior of clusters has often no equivalence at the macroscopic scale, as they are controlled by their high specific surface and their finite size. These concerns the physical chemistry of the mesoscopic world, as illustrated by the recent experimental study driven by the "Reaction dynamics" group of DRECAM/SPAM-Laboratoire Francis Perrin in collaboration with a theoretician team from Paris VI University.

23-03-2007
V. Brenner, F. Piuzzi, I. Dimicoli, B. Tardivel, and M. Mons

One of the great mysteries of life is its lack of symmetry at the molecular scale. Many biological molecules, like amino acids, exist a priori in two asymmetrical forms, "right” and “left”. Such molecules are referred to as “chiral” . Like the two hands, these forms cannot be superimposed but are mirror images of each other (Fig.). However, in living organisms, proteins are exclusively built up from “left” amino acids. This selection of only one form remains one of the great scientific enigmas, which physicists, chemists and biologists try to solve.

Proteins are extremely long chains of amino acids. Each amino acid is added by formation of a peptide bound (CONH) and release of a water molecule, leaving a residue attached to the chain. Within the cells, the proteins thus formed are folded and their function depends not only on their sequence but also on their conformation. This makes the studies of the fundamental mechanisms of protein folding of strong interest.
By studying both experimentally and theoretically the folding of simple peptides, made of two amino acids, researchers from the "Service des Photons, Atomes et Molécules” of CEA-Saclay have obtained new results documenting the issue of chirality of the living world.

16-03-2007
J.M. Mestdagh, L. Poisson, I. Fischer, P. D’Oliveira
Service des Photons, Atomes et Molécules DRECAM/SPAM

The very new laser of the "Plateforme Laser Femtoseconde Accordable, PLFA" began to be installed last year within the Service of Photons Atoms and Molecules (SPAM). It belongs to the infrastructure SLIC, member of the European network LASERLAB-EUROPE and is thus accessible to European scientists. It was designed according to several bets: high repetition rate (1 Khz), strong pulse energy (up to 13mJ, at 800nm), broad accordability (500-750nm) and ultra-fast pulses (<35 fs = 35 10-15 s).

The requirement of a wide wavelength range, even difficult to realize, is necessary to allow decisive progress in physico-chemistry of fast reactions. The requirements in pulse duration were chosen to probe efficiently the dynamics of reactions.

Research in that field began within DRECAM at the beginning of the 90's. They led to a revolution in physico-chemistry: the duration of the energy flow within organic or bio-organic molecules often scales within the sub-picosecond time range. This was at variance with the models usually used of redistribution of energy by coupling between electronic excitation and vibration.

The PLFA project is essential to offer a more complete approach: it allows at the same time energy studies, by adjusting the quantity of energy deposited in the system, selectivity by the accordability of the source and time studies at the femtosecond scale.

08-06-2007
Nuclear magnetic resonance (NMR) is an indispensable technique for studying matter. It can be applied to medical imaging (MRI) to obtain 2D and 3D images of the human body. While it opens the door to a wealth of physicochemical information by harnessing the fundamental properties of matter, NMR remains a technique with poor sensitivity, making it very difficult to use on small quantities of solid or heterogeneous material. A group of scientists from the CEA research department dedicated to condensed matter, atoms and molecules (DRECAM) is pushing back this limit by using miniaturised mobile detectors to capture the NMR signal with high resolution and a 10-fold increase in sensitivity for sample volumes of a few hundred nanolitres.

To increase in sensitivity on small samples, it is necessary to approach as much as possible the detector (coils surrounding the sample). So, the difficulty to obtain a spectrum high resolution seems insurmountable since it would be necessary to place the sample in a micro-capillary tube and then spun at several thousand revolutions per second in a stable and reproducible way inside a micro-detector (coil) with an interior diameter of a few hundred microns. To meet this challenge, the CEA team (D. Sakellariou, G. LeGoff and J.-F. Jacquinot) came up with an innovative solution by spinning the micro-detector (coil) and sample in one piece, with power to the detector supplied via induction from an exterior coil, which also enabled the (wireless) transmission of the desired signal. The whole system spins at thousands of revolutions per second, and probably constitutes the world's fastest set of rotating antennas.

13-04-2007
P. Viswanath, J. Daillant, L. Belloni, M. Alba, DRECAM/SCM – Service de Chimie Moléculaire, S. Mora (LCVN, Montpellier) et O. Konovalov (ESRF).

When a salt like NaCl is dissolved in water, sodium and chlorine separate in ionic form Na+ and Cl-, become surrounded by water molecules and disperse. This deeply modifies the nature of the solvent which becomes for example, a good electricity conductor. At the surface, the distribution of the ions remains however poorly known, although many "contact" properties depend on it.

Thus, why the surface stress of water decreases with HCl whereas it increases with NaCl? Why KCl is twice more effective than NaCl to crystallize the lysozyme [1] ? Questions of this type, which illustrate the ionic specificity, abound in biology, science of the environment and the atmosphere, sciences of materials, physicochemistry… These effects, which some were described by Hofmeister in 1888 [2], are still not fully explained today. Up to now, only empirical laws were given from macroscopic observations. The difficulty holds from that these effects are primarily due to very short range (below 1 nanometer) strong couplings between the ions and the solvent molecules, and from the lack of measurements of ionic profiles at the interfaces.

27-06-2007

Researchers at the Institute of Electronics, Microelectronics and Nanotechnologie (IEMN / CNRS – Universités Lille 1 and Valenciennes, Institut supérieur de l’électronique et du numérique-ISEN) and  the Solid-state Physics Division at the French Atomic Energy Agency (CEA), have succeeded in making transistors from carbon nanotubes on a silicon substrate. The transistors, which are mainly used as automatic switches, can reach cutoff frequencies of 30 GHz [1]which improves by a factor of 4 the previous record obtained by the same teams in August 2006. This result opens up new prospects for mainstream applications which require high operating frequencies.

08-06-2007
Nuclear magnetic resonance (NMR) is an indispensable technique for studying matter. It can be applied to medical imaging (MRI) to obtain 2D and 3D images of the human body. While it opens the door to a wealth of physicochemical information by harnessing the fundamental properties of matter, NMR remains a technique with poor sensitivity, making it very difficult to use on small quantities of solid or heterogeneous material. A group of scientists from the CEA research department dedicated to condensed matter, atoms and molecules (DRECAM) is pushing back this limit by using miniaturised mobile detectors to capture the NMR signal with high resolution and a 10-fold increase in sensitivity for sample volumes of a few hundred nanolitres.

To increase in sensitivity on small samples, it is necessary to approach as much as possible the detector (coils surrounding the sample). So, the difficulty to obtain a spectrum high resolution seems insurmountable since it would be necessary to place the sample in a micro-capillary tube and then spun at several thousand revolutions per second in a stable and reproducible way inside a micro-detector (coil) with an interior diameter of a few hundred microns. To meet this challenge, the CEA team (D. Sakellariou, G. LeGoff and J.-F. Jacquinot) came up with an innovative solution by spinning the micro-detector (coil) and sample in one piece, with power to the detector supplied via induction from an exterior coil, which also enabled the (wireless) transmission of the desired signal. The whole system spins at thousands of revolutions per second, and probably constitutes the world's fastest set of rotating antennas.

28-03-2007
M.-A. Dubois1, L. H. Emmons2, L. Cournac3, P. Chatelet4, N. C. A. Pitman5, V. Vilca5, & L.-F. del Aguila6

1CEA Saclay, DSM/DRECAM/Service de Physique de l ’Etat Condensé, L ’Orme des Merisiers, 91191 Gif sur Yvette, France
2Department of Zoology NHB 390 MRC 108, Smithsonian Institution, P.O.Box 37012,Washington, DC 20013-7012 USA
3CEA Cadarache, DSV/DEVM/Laboratoire d ’Ecophysiologie de la Photosynthèse, 13108 Saint Paul Lez Durance Cedex, France
4CNRS/URA 1183,Muséum National d ’Histoire Naturelle,
4 avenue du Petit Château,91800 Brunoy, France
5Asociación para la Conservación de la Cuenca Amazonía,
Calle Cuzco 499, Puerto Maldonado, Madre de Dios, Perú
6Fundación Amigos de la Naturaleza, Santa Cruz de la Sierra, Bolivia

07-02-2007

M. Roger1, D.J.P Morris2, D.A. Tennant3,4, M.J. Gutmann5, J.P. Goff2, J.-U. Hoffmann3, R. Feyerherm3, E. Dudzik3, D. Prabhakaran6, A.T. Boothroyd6, N. Shannon7, B. Lake3,4 & P.P. Deen8.

1Service de Physique de l’Etat Condensé (CNRS/MIPPU/URA 2464), DSM/DRECAM/SPEC, CEA Saclay, P.C. 135, F-91191 Gif sur Yvette, France.
2Dept. of Physics, University of Liverpool, Oliver Lodge Laboratory, Liverpool L69 7ZE, UK.
3Hahn-Meitner Institute, Glienicker Strasse 100, Berlin D-14109 Germany.
4Institute für Festkörperphysik, Technische Universität Berlin, Hardenbergstrasse 36, Berlin D-10623 Germany,
5ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 OQX, UK.
6Clarendon Laboratory, Parks Road, Oxford OX1 3PU, UK.
7H.H Wills Physics Laboratory, University of Bristol, Bristol BS8 1TL, UK.
8European Synchrotron Radiation Facility, BP 220, F-38043 Grenoble Cedex, France.

27-01-2007
A. Chiffaudel, F. Daviaud, B. Dubrulle, C. Gasquet, R. Monchaux, V. Padilla, avec la participation de L. Marié et F. Ravelet, DSM/DRECAM/SPEC
Collaboration VKS : CEA – ENS Lyon – ENS Paris -

Many research teams aim at understanding of the origin and behavior of the magnetic field of planets and stars. The VKS1 collaboration (gathering researchers at CEA, CNRS, Ecoles normales supérieures in Lyon and Paris) has succeeded in generating a magnetic field from a highly turbulent liquid sodium flow in a laboratory experiment. Although the extreme conditions specific to astrophysical and geophysical media are out of reach in the laboratory, the observed magnetic field shares remarkable similarities with cosmic fields. Their observations are reported in the January 26th issue of Physical Review Letters (see also the "Physical review Focus").

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