Pages scientifiques 2004
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Topic 1 : Effects of Extreme Conditions in Radiation Chemistry In numerous real situations, radical reactions occur with extreme thermodynamic conditions like temperature over 300°C, with pressure over 100 MPa, or triggered by nuclear reactions which produce elevated Linear Energy Transfer (LET) ionizing particles[1]. These parameters can induce drastic changes in the production and in the reactivity of radical species in water. The most recent data bases[2] show a lack of knowledge. Therefore the effect of the combinations of extreme values of these conditions has never been considered: high temperature water submitted to high LET particles for instance. In the context of the generation 4 nuclear power plant systems in which temperatures of fluid transfer should increase in order to improve the thermal-cycle yield, one system expected to be developed will involve supercritical water (374°C, 22 MPa). Consequently many fundamental questions on water radiolysis in these conditions appeared since Arrhenius extrapolation could not be applied. How to predict water decomposition in these conditions? That was essentially the aim of Dimitri Saffré PhD (2008-2011) who has performed experiments and MC simulations in a large range of temperature and LET in order to determine radiolytic yields and rate constants through an extreme condition-resistant chemical system: HBr. In situ analysis of Br-, Br2- and Br3- species allowed the determination of HOŸ yields in various conditions of irradiation: X-rays at ESRF (FAME Line, J.L. Hazeman), ns-electron pulses from ALIENOR accelerator in LRAD, ps-electron pulses from ELYSE in LCP/Orsay (M. Mostafavi), pulsed heavy ions in GANIL (E. Balanzat), helion beam in ARRONAX at Nantes (M. Fattahi). During this study a novel high temperature/high pressure cell has been designed and used with high LET particles (figure 1). Only a part of the work was published[3]. Publications of valuable results (figure 2) are still on the way because they are waiting for the comparison with MC simulations performed in collaboration with B. Gervais (CIMAP Caen) and M. Beuve (IPN Lyon). In parallel implementation of water radiation chemistry has been performed in the open source program GEANT4 in the ANR named GEANT4-DNA (2009-2012) by collaborating with S. Incerti (CENBG Bordeaux)[4]. Another high pressure system has been designed recently to reach 400 MPa with a flow and optical windows for pulse radiolysis experiments[5]. This system is devoted to the analysis of protein such as myoglobine under pressure stress in order to probe their tertiary structure and their reactivity towards water radical. (see topic 2)
[1] Baldacchino, G. et Hickel, B.. In: Hors série « Radiation Chemistry » de l’Actualité Chimique Sciences, E. (Editor) EDP Sciences; 2008. [2] Elliot, A.J. et Bartels, D.M. The Reaction Set, In: AECL; 2009 [3] Saffré, D. et al., (2011) Journal of Physics: Conference Series, 261, 012013 [4] Incerti, S. et al., (2010) Medical Physics, 37, 4692-4708. [5] Nguyen Le, D.T., et al. (2013) NIMS B, 299, 1-7 [6] Rapport à 6 mois sur l’avancement du projet SIRMIO – compte rendu de la réunion d’avancement du 8 mars 2013, convention Plan Cancer PC201204. |
Fig.1: Picture of the optical cell designed for high LET particle irradiations.
Fig.2: Transient signals at 357nm for various high temperatures of Br2- (formation) and Br- (bleaching) in a 10mM NaBr solution irradiated by 130µs pulses of C6+ of 975MeV.
We are currently developing a new approach to analyze the fundamental aspects of the energy Deposition of swift Heavy Ions in Liquid Water (SIRMIO project 2012-2014). It should induce application in real time microdosimetry during hadrontherapy. This project consists in using fluorescence of molecule produced during radiolysis and observed by optical microscopy and fast detection of fluorescence induced by laser excitation. We expect to get images of energy deposition of energetic ions at micrometer scale with high time resolution as well. After 6 months of work[6] the 4 partners got strong knowledge of the molecules to use, in terms of toxic effect in living cells, of radiolytic mechanisms and also purity, radiolytic yields. During these investigations, new methods in radiation chemistry should be available such as pulse radiolysis method with fluorescence induced by laser, and also a method to obtain the fluorescence lifetime coupled to alpha ionization (developed at IPHC Strasbourg). We expect to use very soon the microscopy in line with Van de Graaf accelerator, microprobe at LEEL in Saclay to reach our objectives. |
Nombreuses sont nos études en femtochimie ayant fait l’objet de publications au cours de ces quatre dernières années. Elles ont portées essentiellement sur les transferts de proton/électron mais aussi sur les mécanismes de solvatation et de relaxation intramoléculaire. Dans le cadre de cette page web, nous avons souhaité mettre l’accent sur les mécanismes de relaxation de cations radicaux aromatiques. Ces cations, présents dans les nuages interstellaires, peuvent être stabilisés dans des verres d’acide borique. Nous avons entrepris cette étude car les connaissances de la littérature ne permettaient pas de dégager un comportement rationnel de ces espèces en fonction de leurs niveaux énergétiques et en fonction de la température. Une expérience de réseau transitoire nous a permis de mettre en évidence une composante ultrarapide (~200 fs) et une composante beaucoup plus longue (quelques picosecondes) dans le processus de relaxation.
En employant des techniques issues de la spectroscopie laser, nous avons étudié les mouvements de la liaison hydrogène (OH…O). Le couplage entre les rotations du vibrateur OH et l’élongation de la liaison hydrogène a été étudié. Les forces induisant la rotation des molécules d’eau dépendent de leur distance, ce qui introduit une corrélation entre ces degrés de liberté. La dynamique du réseau de liaisons hydrogène génère des arrangements tétraédriques fluctuants qui déterminent la durée de vie de la liaison hydrogène. L’objet de cette étude théorique est d’interpréter dans un modèle basé sur la physique statistique non-linéaire des expériences qui ont permis de "filmer" les rotations de HOD dans un mélange HOD/D2O.
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Topic 1 : Effects of Extreme Conditions in Radiation Chemistry In numerous real situations, radical reactions occur with extreme thermodynamic conditions like temperature over 300°C, with pressure over 100 MPa, or triggered by nuclear reactions which produce elevated Linear Energy Transfer (LET) ionizing particles[1]. These parameters can induce drastic changes in the production and in the reactivity of radical species in water. The most recent data bases[2] show a lack of knowledge. Therefore the effect of the combinations of extreme values of these conditions has never been considered: high temperature water submitted to high LET particles for instance. In the context of the generation 4 nuclear power plant systems in which temperatures of fluid transfer should increase in order to improve the thermal-cycle yield, one system expected to be developed will involve supercritical water (374°C, 22 MPa). Consequently many fundamental questions on water radiolysis in these conditions appeared since Arrhenius extrapolation could not be applied. How to predict water decomposition in these conditions? That was essentially the aim of Dimitri Saffré PhD (2008-2011) who has performed experiments and MC simulations in a large range of temperature and LET in order to determine radiolytic yields and rate constants through an extreme condition-resistant chemical system: HBr. In situ analysis of Br-, Br2- and Br3- species allowed the determination of HOŸ yields in various conditions of irradiation: X-rays at ESRF (FAME Line, J.L. Hazeman), ns-electron pulses from ALIENOR accelerator in LRAD, ps-electron pulses from ELYSE in LCP/Orsay (M. Mostafavi), pulsed heavy ions in GANIL (E. Balanzat), helion beam in ARRONAX at Nantes (M. Fattahi). During this study a novel high temperature/high pressure cell has been designed and used with high LET particles (figure 1). Only a part of the work was published[3]. Publications of valuable results (figure 2) are still on the way because they are waiting for the comparison with MC simulations performed in collaboration with B. Gervais (CIMAP Caen) and M. Beuve (IPN Lyon). In parallel implementation of water radiation chemistry has been performed in the open source program GEANT4 in the ANR named GEANT4-DNA (2009-2012) by collaborating with S. Incerti (CENBG Bordeaux)[4]. Another high pressure system has been designed recently to reach 400 MPa with a flow and optical windows for pulse radiolysis experiments[5]. This system is devoted to the analysis of protein such as myoglobine under pressure stress in order to probe their tertiary structure and their reactivity towards water radical. (see topic 2)
[1] Baldacchino, G. et Hickel, B.. In: Hors série « Radiation Chemistry » de l’Actualité Chimique Sciences, E. (Editor) EDP Sciences; 2008. [2] Elliot, A.J. et Bartels, D.M. The Reaction Set, In: AECL; 2009 [3] Saffré, D. et al., (2011) Journal of Physics: Conference Series, 261, 012013 [4] Incerti, S. et al., (2010) Medical Physics, 37, 4692-4708. [5] Nguyen Le, D.T., et al. (2013) NIMS B, 299, 1-7 [6] Rapport à 6 mois sur l’avancement du projet SIRMIO – compte rendu de la réunion d’avancement du 8 mars 2013, convention Plan Cancer PC201204. |
Fig.1: Picture of the optical cell designed for high LET particle irradiations.
Fig.2: Transient signals at 357nm for various high temperatures of Br2- (formation) and Br- (bleaching) in a 10mM NaBr solution irradiated by 130µs pulses of C6+ of 975MeV.
We are currently developing a new approach to analyze the fundamental aspects of the energy Deposition of swift Heavy Ions in Liquid Water (SIRMIO project 2012-2014). It should induce application in real time microdosimetry during hadrontherapy. This project consists in using fluorescence of molecule produced during radiolysis and observed by optical microscopy and fast detection of fluorescence induced by laser excitation. We expect to get images of energy deposition of energetic ions at micrometer scale with high time resolution as well. After 6 months of work[6] the 4 partners got strong knowledge of the molecules to use, in terms of toxic effect in living cells, of radiolytic mechanisms and also purity, radiolytic yields. During these investigations, new methods in radiation chemistry should be available such as pulse radiolysis method with fluorescence induced by laser, and also a method to obtain the fluorescence lifetime coupled to alpha ionization (developed at IPHC Strasbourg). We expect to use very soon the microscopy in line with Van de Graaf accelerator, microprobe at LEEL in Saclay to reach our objectives. |
Dans de nombreux matériaux, le passage d’un rayonnement ionisant conduit à la formation d’espèces ioniques et radicalaires qui réagissent entre elles et avec leur environnement. Des impulsions d’électrons ou de particules permettent de déclencher des réactions chimiques élémentaires dont les cinétiques peuvent être suivies en temps réel. ALIENOR, l’accélérateur linéaire d’électrons de 10 MeV pour la radiolyse est l’outil de choix pour ces études en milieu poreux et aux interfaces solide-liquide.
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Topic 1 : Effects of Extreme Conditions in Radiation Chemistry In numerous real situations, radical reactions occur with extreme thermodynamic conditions like temperature over 300°C, with pressure over 100 MPa, or triggered by nuclear reactions which produce elevated Linear Energy Transfer (LET) ionizing particles[1]. These parameters can induce drastic changes in the production and in the reactivity of radical species in water. The most recent data bases[2] show a lack of knowledge. Therefore the effect of the combinations of extreme values of these conditions has never been considered: high temperature water submitted to high LET particles for instance. In the context of the generation 4 nuclear power plant systems in which temperatures of fluid transfer should increase in order to improve the thermal-cycle yield, one system expected to be developed will involve supercritical water (374°C, 22 MPa). Consequently many fundamental questions on water radiolysis in these conditions appeared since Arrhenius extrapolation could not be applied. How to predict water decomposition in these conditions? That was essentially the aim of Dimitri Saffré PhD (2008-2011) who has performed experiments and MC simulations in a large range of temperature and LET in order to determine radiolytic yields and rate constants through an extreme condition-resistant chemical system: HBr. In situ analysis of Br-, Br2- and Br3- species allowed the determination of HOŸ yields in various conditions of irradiation: X-rays at ESRF (FAME Line, J.L. Hazeman), ns-electron pulses from ALIENOR accelerator in LRAD, ps-electron pulses from ELYSE in LCP/Orsay (M. Mostafavi), pulsed heavy ions in GANIL (E. Balanzat), helion beam in ARRONAX at Nantes (M. Fattahi). During this study a novel high temperature/high pressure cell has been designed and used with high LET particles (figure 1). Only a part of the work was published[3]. Publications of valuable results (figure 2) are still on the way because they are waiting for the comparison with MC simulations performed in collaboration with B. Gervais (CIMAP Caen) and M. Beuve (IPN Lyon). In parallel implementation of water radiation chemistry has been performed in the open source program GEANT4 in the ANR named GEANT4-DNA (2009-2012) by collaborating with S. Incerti (CENBG Bordeaux)[4]. Another high pressure system has been designed recently to reach 400 MPa with a flow and optical windows for pulse radiolysis experiments[5]. This system is devoted to the analysis of protein such as myoglobine under pressure stress in order to probe their tertiary structure and their reactivity towards water radical. (see topic 2)
[1] Baldacchino, G. et Hickel, B.. In: Hors série « Radiation Chemistry » de l’Actualité Chimique Sciences, E. (Editor) EDP Sciences; 2008. [2] Elliot, A.J. et Bartels, D.M. The Reaction Set, In: AECL; 2009 [3] Saffré, D. et al., (2011) Journal of Physics: Conference Series, 261, 012013 [4] Incerti, S. et al., (2010) Medical Physics, 37, 4692-4708. [5] Nguyen Le, D.T., et al. (2013) NIMS B, 299, 1-7 [6] Rapport à 6 mois sur l’avancement du projet SIRMIO – compte rendu de la réunion d’avancement du 8 mars 2013, convention Plan Cancer PC201204. |
Fig.1: Picture of the optical cell designed for high LET particle irradiations.
Fig.2: Transient signals at 357nm for various high temperatures of Br2- (formation) and Br- (bleaching) in a 10mM NaBr solution irradiated by 130µs pulses of C6+ of 975MeV.
We are currently developing a new approach to analyze the fundamental aspects of the energy Deposition of swift Heavy Ions in Liquid Water (SIRMIO project 2012-2014). It should induce application in real time microdosimetry during hadrontherapy. This project consists in using fluorescence of molecule produced during radiolysis and observed by optical microscopy and fast detection of fluorescence induced by laser excitation. We expect to get images of energy deposition of energetic ions at micrometer scale with high time resolution as well. After 6 months of work[6] the 4 partners got strong knowledge of the molecules to use, in terms of toxic effect in living cells, of radiolytic mechanisms and also purity, radiolytic yields. During these investigations, new methods in radiation chemistry should be available such as pulse radiolysis method with fluorescence induced by laser, and also a method to obtain the fluorescence lifetime coupled to alpha ionization (developed at IPHC Strasbourg). We expect to use very soon the microscopy in line with Van de Graaf accelerator, microprobe at LEEL in Saclay to reach our objectives. |
Les séparations membranaires font appel à des matériaux polymères caractérisés par leur structure, le diamètre de leur porosité et leurs propriétés physiques ou chimiques. L’irradiation avec des ions lourds traversant le matériau, suivie d'une attaque chimique du polymère permet d'obtenir la formation de pores cylindriques parallèles les uns aux autres, orientés selon la trajectoire incidente des particules. Des films de poly(téréphtalate d'éthylène) ont été irradiés et attaqués, puis la polymérisation chimique du pyrrole sur les surfaces et les pores des films a été effectuée. L'épaisseur du film, le nombre d'ions par cm² et le diamètre des pores (paramètres de l'attaque chimique) définissent les caractéristiques de la membrane finale. On obtient une "membrane creuse ", dont la longueur des tubes atteint 100 micromètres tandis que le diamètre de ces derniers varie de 150 à 500 nanomètres (LSI, collaboration PROFILTRA).
