Dissertationen zum Thema „Degrés d'oxydation“
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Hilaire, Sandrine. „Etude de la stabilisation des hauts degrés d'oxydation des actinides“. Paris 11, 2005. http://www.theses.fr/2005PA112031.
Der volle Inhalt der QuelleEarly actinides (U, Np, Pu, Am) in a high oxidation state show a particular linear structure in bonding with pi-donor ligands (O, NR,. . . ). The diminution of the charge on the metallic centre due to the electronic donation from the equatorial and axial ligands allow the existence of high oxidation states for the light actinide. The particularity of the actinide stands in the fact that An 5f orbitals can take part in chemical bonding because of a partial delocalisation. In order to understand this behaviour, a study of the electronic and the geometric structure is undertaken using both theorical and experimental approaches : - Modelling of geometry and IR vibrational frequencies of compounds with formula AnO2L2n+(H2O)3 (An= U(VI) 5f0, Np(V) 5f2, Np(VI) 5f1 and Np(VII) 5f°, L=CI-, Br-, F-, CO32- and OH-) were performed by the density functional theory (DFT) using Gaussian and ADF software. Bond population and molecular orbitals composition were essentially studied. - Hydroxide, carbonate and oxalate of Neptunium (+V) and (+VI) were synthesized with the aim to study the electronic properties by different experimental way: magnetism susceptibility (SQUID), Mossbauer, XPS measurements and vibrationals spectroscopy's. - Uranium studies are focused on the water free compounds UO2Cl2(THF)3, UO2(OPPh3)4(Otf)2 and UO2(OTf)2, exhibiting more covalent bonds in the equatorial plane
Dinoi, Chiara. „Complexes oxyde de molybdène et de tungstène dans les hauts degrés d'oxydation en milieu aqueux : synthèse, réactivité et catalyse d'oxydation“. Toulouse 3, 2007. http://thesesups.ups-tlse.fr/120/.
Der volle Inhalt der QuelleAfter a bibliographic introduction on the aqueous chemistry of high oxidation state Mo and W organometallic oxido complexes (chapter I), chapter II describes the reduction of [Cp2Mo2O5] in organic media with the thiols R-SH (R = iPr, Et, tBu). The undesired decomposition of [Cp2Mo2O5] in the presence of water has turned our efforts toward the study of the analogous [Cp*2Mo2O5] and [Cp*2W2O5] complexes, highly stable in aqueous media as already reported in the literature. In chapter III, a new synthesis of [Cp*2Mo2O5] and [Cp*2W2O5] is presented, high yields being respectively achieved in only two steps. Chapter IV reports studies of the chemical reactivity of [Cp*2Mo2O5] towards selected functionalized mercaptanes in aqueous media. With SHCH2COOH (mercaptoacetic acid) a spontaneous reduction affords the [Cp*2Mo2(micron-SCH2CO2)2(micron-S)] complex, whereas in the presence of HSCH2CH2COOH (mercaptopropionic acid), the oxido compound [Cp*2Mo2(micron-SCH2CH2CO2)2(micron-O)] is formed. .
Cachia, Jean-Nicolas. „Solubilité d'éléments aux degrés d'oxydation III et IV dans les verres de borosilicate“. Montpellier 2, 2005. http://www.theses.fr/2005MON20165.
Der volle Inhalt der QuelleKappenstein-Grégoire, Anne Cécile. „Caractérisation physico-chimique des solutions aqueuses de nitrate de neptunium aux degrés d'oxydation (IV) et (V)“. Paris 6, 2001. http://www.theses.fr/2001PA066318.
Der volle Inhalt der QuelleBesson, Claire. „Huat degrés d'oxydation du ruthénium et ligands polyoxométallates : du transfert d'azote à l'oxydation catalytique de l'eau“. Paris 6, 2009. http://www.theses.fr/2009PA066350.
Der volle Inhalt der QuelleGondouin, Serge. „Caractérisation in situ des degrés d'oxydation III et VI du chrome à l'état solide par spectrométrie de masse LAMMA“. Metz, 1986. http://docnum.univ-lorraine.fr/public/UPV-M/Theses/1986/Gondouin.Serge.SMZ8618.pdf.
Der volle Inhalt der QuelleThe chromium in its oxudation states is known as being able to be carcinogen for man his environment. In consequence it is necessary to characterize perfectly these oxidation states and particularly in stainless steel fumes. The methodology developed hier is based on result obtaind in the course of analyses either of pure compounds (oxides or salts) or of compounds on support or included in matrices. From this study conclude that cluster ions formed in micro-plasma are representative of chemical environment of the studied element. In the same way we could evidenced the effect of compounds hydratation of these ionized clusters. For each sample type, we make up a histogram elementary ions repartition for cluster ions (negative characteristic of sulfate, nitrate. . . Ions). In all cases we verified the composition determination with several other techniques such as E. S. C. A. , I. R. T. F, R. X. And Raman. Our results allowed to conform the LAMMA analysis, evidencing advantages and limits on each one
Sakout, Mohammed. „Contribution de la spectrométrie X à l'étude des degrés d'oxydation du vanadium et du chrome dans les oxydes mixtes de structure spinelle“. Rouen, 1989. http://www.theses.fr/1989ROUES002.
Der volle Inhalt der QuelleAharonian, Ghazar. „Reactivité de dérivés moléculaires du niobium et du tantale dans les degrés d'oxydation III à I avec des ligands assembleurs : complexes imido et diiminés“. Nice, 1988. http://www.theses.fr/1988NICE4177.
Der volle Inhalt der QuellePagliarini, Olivio. „Chimie moléculaire du niobium et du tantale dans les degrés d'oxydation IV à II : synthèse et réactivité d'alcoxydes du tantale et du bis(cyclopentadienyl)niobium (II)“. Nice, 1987. http://www.theses.fr/1987NICE4131.
Der volle Inhalt der QuelleBaranov, Alexeï. „Apport de la spectroscopie Mössbauer à l'étude des phénomènes électroniques et structuraux au sein de réseaux oxygénés renfermant un élément de transition à un degré d'oxydation élevé“. Bordeaux 1, 2007. http://www.theses.fr/2007BOR13449.
Der volle Inhalt der QuelleThis thesis is devoted to the study of electronic phenomena, structural and magnetic transitions through Mössbauer Spectroscopy using 57Fe as local probe (1 to 2% at. ). Three different matrixes have been selected: (i) the nickelates TNiO3 with the perovskite structure (T=rare-earth, Y, Tl), (ii) the copper 3+ oxides: LaCuO3 with the perovskite structure, SrLaCuO4 and La2Li0. 50Cu0. 50O4 with the K2NiF4-type structure, (iii) the oxide CaMn7O12 with a structure derived from the perovskite (CaMn )(Mn Mn4+)O12 where a Jahn-Teller cation (Mn3+) can occupy the A site. Mössbauer spectroscopy has allowed to underline the following electronic and structural phenomena: (i) for the TNiO3 matrixesthe insulationmetal transition, the disproportionation, the magnetic ordering involving two Ni3+ electronic configurations; (ii) for the Cu3+ Oxides: the charge transfert Cu3+ O Cu2+ OL; (iii) in the case of CaMn7O12 matrix two phenomena: a second order structural transition (rhomboedral cubic) (387T455 K), a second order magnetic transition close to 90 K
Aubriet, Frédéric. „Etude par spectrométrie de masse de la formation des agrégats ionisés induits par ablation/ionisation laser de composés minéraux : application à la différenciation des degrés d'oxydation du chrome“. Metz, 1999. http://docnum.univ-lorraine.fr/public/UPV-M/Theses/1999/Aubriet.Frederic.SMZ9949.pdf.
Der volle Inhalt der QuelleAlves, de Sousa Rodolphe. „Composés organiques soufrés bis-fonctionnalisés par deux soufres à des degrés d'oxydation différents : synthèse et réactivité vis-à-vis de complexes Zn(N2S2) apparentés à des motifs doigts de zinc“. Paris 5, 2009. http://www.theses.fr/2009PA05S002.
Der volle Inhalt der QuelleCysteines play a key role in biological systems since they have very high affinity for metal in proteins and are easily oxidized into disulfide or more oxidized species. Compounds functionalized by two sulfurs at two different oxidation states were synthesized either by deprotecting p-sulfanyl ethylester derivatives or by alkaline hydrolysis of cyclic thiosulfinate and thiosulfonate. Zn(N2§2) complexes with imine, amine or amidate nitrogen ligands were prepared. Their oxidation with DMD or L^Oa leads to bis-sulfonates as free ligands, except for the bis-imine bis-sulfonate complex that retains zinc. The reactivity of these complexes toward linear and cyclic thiosulfinates or thiosulfonates showed that the bis-amidate complexes were the only ones to react, leading to the free bis-thionylated ligands. Monitoring the release of zinc by UV-vis enables to classify the thiosulfonates according to their reactivity and to propose that the release of zinc occurs after the first thionylation
Le, Motais Brigitte. „Degrés d'oxydation inhabituels de complexes de métaux du groupe V (V,Nb,Ta) créés par radiolyse en milieu non aqueux : étude expérimentale et théorique : essais de synthèse de dérivés hétérométalliques de Niobium et d'Actinide“. Paris 11, 1985. http://www.theses.fr/1985PA112277.
Der volle Inhalt der QuelleByeon, Song-Ho. „Corrélations entre la nature des liaisons chimiques entourant un octaèdre MO6 au sein d' un réseau oxygéné de type K2NIF4 et sa distorsion : influence decelle-ci sur la transition spin faible spin fort du cobalt III et sur la stabilisation du nickel III“. Phd thesis, Université Sciences et Technologies - Bordeaux I, 1991. http://tel.archives-ouvertes.fr/tel-00876417.
Der volle Inhalt der QuelleSözen, Aktas Pelin. „Complexes organométalliques à haut degré d'oxydation du molybdène et du tungstène comme catalyseur d'oxydation“. Toulouse 3, 2012. http://thesesups.ups-tlse.fr/1894/.
Der volle Inhalt der QuelleThe chemistry of molybdenum and tungsten cyclopentadienyl complexes in higher oxidation states with oxo, imido and sulfide ligands has increased in significance. Interest in Cp* oxo molybdenum and tungsten complexes is particularly motivated by their potential in oxidation catalysis. Most advances in the chemistry of molybdenum and tungsten systems involve investigations on oxidation processes. An important need in this area is to find a better and simpler procedure for the synthesis of dinuclear Cp* oxo molybdenum and tungsten complexes. Improved high-yield synthetic routes to the well-known starting compounds [Cp*2M2O5] (M=Mo, W) are described in the thesis. Subsequently, the reactivity of the WVI complex with sulphur donor ligands is presented. This comprises the investigation of the interaction between [Cp*2W2O5] and mercaptocarboxylic acids, especially 3-mercaptopropionic acid, which resulted in the isolation and structural characterization of compound [Cp*WO2(SCH2CH2COOH)]. This is the first reported structure of WVI surrounded by a CpO2(SR) ligand set. Comparison with the results of the corresponding reaction of [Cp*2Mo2O5], which leads to facile metal reduction, shows a greater tendency of the Mo compound to be reduced. For the W complex, on the other hand, a reversible reaction gives rise to a simple Cp*WVI ligand exchange product. The corresponding reaction for thioglycolic acid resulted in an adduct having the same stoichiometry at low substrate/W ratio, but containing a 5-membered cycle in an asymmetric [Cp*WO(OH)(SCH2COO)] structure. However, the deepening of the solution color when using greater substrate/W ratios indicates the intervention of metal reduction to yield several by-products as shown by NMR. Cp*Mo oxo complexes have proven to be efficient catalyst precursors for the epoxidation of olefins and the thesis also focused on the catalytic activity of [Cp*2Mo2O5] with TBHP (in decane) as oxidant in the MeCN/Toluene system. High activities were observed under mild conditions with catalyst loadings as low as %1 and with high chemoselectivities for the epoxidation of cyclooctene. The rate law for the catalyzed process has been derived and the difference with respect to the previously determined rate law for the same process with H2O2 as oxidant is discussed. The activation parameters for the catalytic process have also been derived by the Eyring analysis from variable-temperature kinetic data. A puzzling difference in relative reactivity of the Mo and W systems (W >> Mo when using H2O2, W << Mo when using TBHP), however, remains without a satisfactory rationalization. A detailed investigations of the speciation behavior of the tungsten compound, [Cp*2W2O5], through combined 1H NMR and electrical conductivity studies in a variety of coordinating and dissociating solvents (acetone, DMSO, MeOH, MeCN, H2O) is presented in the thesis. The combined 1H NMR investigations are in complete agreement with the results of the electrical conductivity studies, in the sense that the dominant or exclusive species in all organic solvents is undissociated. These experimental studies demonstrate that at least two species are formed in polar solvents and are corroborated by a computational study
Podda, Olivier. „Solubilité et spéciation de l’uranium dans les liquides aluminosilicatés“. Electronic Thesis or Diss., Université de Lorraine, 2023. http://www.theses.fr/2023LORR0052.
Der volle Inhalt der QuelleIn the frame of the development of new nuclear waste vitrification processes, solid waste with actinides contaminated metals are under interest. Whatever the objective is; waste conditioning or decontamination, this is necessary to solubilize actinides in the molten glass. However, during the high temperature vitrification process, the metallic phase nature modifies the reducing conditions imposed to the molten glass and its redox potential. Such conditions have a strong impact on uranium solubility directly related to its oxidation state. The present study aims to provide important data on the uranium behavior (behavior in the glass melt, crystallization, proportion and structure of oxidation states) over a wide redox range. An approach coupling the determination of the uranium solubility with that of its oxidation states as a function of the conditions of elaboration was set up for the first time. For this purpose, several aluminosilicate glasses belonging to the ternary systems CAS (CaO-Al2O3-SiO2) and MAS (MgO-Al2O3-SiO2) were elaborated and doped with 20%wt of UO2, then the redox conditions were imposed by a CO(g)/CO2(g) gas mixture. The results indicate that the uranium solubility in glasses is dependent on the redox conditions imposed and on the composition of the glass. The study of uranium speciation by high-resolution X-ray absorption spectroscopy (HERFD-XANES) allowed the modelization of the evolution of the proportion of uranium oxidation states as a function of glass melt redox. The structure of the oxidation states was determined by coupling two complementary methods of EXAFS spectra analysis. The results obtained indicate that the structures of UVI and UIV are similar to those determined by different authors in the literature. However, the structure of UV seems to be dependent on the redox conditions
Camp, Clément. „Conception et réactivité de complexes mono- et polymétalliques d'éléments f en bas degré d'oxydation“. Phd thesis, Université de Grenoble, 2013. http://tel.archives-ouvertes.fr/tel-00949379.
Der volle Inhalt der QuelleCLAPPE, CAROLINE. „Etude electrochimique de complexes organometalliques de l'uranium au degre d'oxydation iv“. Paris 6, 1997. http://www.theses.fr/1997PA066275.
Der volle Inhalt der QuelleWEYLAND, TANIA. „Synthese et proprietes de complexes organo-fer bi- et tri- nucleaires sous differents degres d'oxydation“. Rennes 1, 1997. http://www.theses.fr/1997REN10044.
Der volle Inhalt der QuelleDerule, Hervé. „Influence du degré d'oxydation du métal sur la sélectivité des catalyseurs de synthèse Fischer-tropsch“. Poitiers, 1989. http://www.theses.fr/1989POIT2268.
Der volle Inhalt der QuelleGUILLEMOT, MAUD. „Nouveaux composes modeles pour l'electronique moleculaire en serie fe-cr-fe isolables sous 4 degres d'oxydation“. Rennes 1, 1998. http://www.theses.fr/1998REN10172.
Der volle Inhalt der QuelleGoure, Eric. „Réactions de transfert d'amines fonctionnalisées catalysées par des systèmes binucléaires de fer non hémiques : intermédiaires à haut degré d'oxydation“. Grenoble 1, 2008. http://www.theses.fr/2008GRE10115.
Der volle Inhalt der QuelleWith the aim of understanding mechanisms of metal-catalyzed amine transfer reactions, we have synthesized a diiron complex with an internal aromatic substrate. In presence of amine donor as ArINTs, this complex performs the quantitative intramolecular aromatic amination of a benzyl group of the ligand and this amination produces both mono and bis(tosylamine) derivatives. The amination mechanism fully characterized. We have been provide indirect evidences for both a FeIIIFeIV(=NTs) and a FeIVFeIV(=NTs)(NHTs) intermediate using isotope labelling experiments coupled with ESI-MS analysis and HPLC quantification of reaction products. The second part of this work deals with a non heme mixed valence diiron complex with an aniline ligand. The reversible deprotonation of the aniline group leads to the formation of the corresponding anilinate complex and induces a valence inversion of the metal ions
Bordage, Amélie. „Propriétés spectroscopiques et structure électronique du vanadium dans des matériaux complexes : implications géologiques et technologiques“. Phd thesis, Université Pierre et Marie Curie - Paris VI, 2009. http://tel.archives-ouvertes.fr/tel-00459909.
Der volle Inhalt der QuelleD'accriscio, Florian. „Complexes de nickel caméléons : exploration de tous ses degrès d'oxydation pour la formation de liaisons C-C et C-CF3“. Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30216.
Der volle Inhalt der QuelleThis research project aims at the study of nickel complexes in different oxidation states (from 0 to +IV) in order to promote C–C and C–CF3 bond formation. In a first part, low-valent nickel complexes are used as catalysts to perform Negishi and Suzuki-Miyaura cross-coupling reactions. If the C–C bond formation is a well-known reaction using palladium catalysts, the use of nickel complexes as catalysts is more complicated to understand in the mechanistic aspect. In this work, the key point is the use of a bis-phosphine ligand which allows the synthesis and isolation of nickel(0) complexes. A full mechanistic study via stoichiometric reactions as well as DFT calculations confirms that the Negishi cross-coupling works only on a Ni(0)/Ni(II) catalytic cycle. Surprisingly, preliminary studies on the Suzuki-Miyaura cross-coupling reactions show that the mechanism pathway is completely different. In a second part, our interest is focused on the C–CF3 bond formation using high-valent nickel complexes. In chemical industries, the C–CF3 bond formation requires harsh conditions and also produces toxic waste for the environment. This mainly explains why the use of transition metals is still challenging in this topic. However in the last few years, the interest for the use of nickel complexes as coupling agent for C–CF3 bond formation has grown. This work deals with the synthesis of nickel(III) complexes bearing two CF3 substituents and the use of a dimeric nickel(III) complex as a building block for the formation [NiIII(CF3)2] type complexes. If these species do not promote the C–CF3 cross coupling, a nickel(IV) complex shows its ability to create this bond. Moreover, this is the first nickel(IV) species bearing both fluorine and CF3 substituents at the same metal center and promoting C–H bond activation
Cavaillé, Anthony. „Complexes de fer à bas degré d'oxydation pour l'activation du diazote atmosphérique, extension aux liaisons C-H et au phosphore blanc“. Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30338.
Der volle Inhalt der QuelleMolecular nitrogen activation and functionalization are one of the most challenging topic in modern chemistry. The industrial formation of ammonia by the Haber-Bosch process, essential for current agriculture, is the starting point of this field. Indeed, the strong energetic need of this transformation has motivated academic research to find catalyst that can work in milder conditions as observed with nitrogenase enzymes. The principal goal of this Ph.D. work was the synthesis and the study of low oxidation states iron complexes bearing triphosphine ligand for the catalytic formation of ammonia and silylamines. This experimental work was supported by theoretical calculation using DFT in order to rationalize and understand the different results. The first part of this manuscript presents the metallic precursors synthesis and the first reduction attempts using Grignard reagents. During this part, the formation of an interesting Fe0 bis-dinitrogen complex was observed. Its efficient synthesis and reactivity was studied in a second part. This complex is one of the few homogeneous iron catalysts able to perform the formation of ammonia and one of the most active for N(TMS)3 formation. Furthermore, this Fe0 center is able to dehydrogenate an alkane part of its ligand and activate another small molecule of interest, white phosphorus. This new reaction leads to the firs example of the formation of an end-deck iron cyclo-P4 complex and is the subject of the third part. Finally, several iron complexes bearing dinitrogen and hydride ligand were studied in relevance with the nitrogenase enzyme. This part was an opportunity for a change toward a PCP-type ligand. The carbenic form of this ligand was reachable by double C-H activation at an intermediate Fe0 center
CONDAMINES, NICOLE. „Contribution a l'etude de l'extraction d'acides mineraux et de cations actinides aux degres d'oxydation 4 et 6 par des n, n-dialkylamides“. Paris 6, 1989. http://www.theses.fr/1989PA066111.
Der volle Inhalt der QuelleGondouin, Serge. „Caractérisation in situ des degrés d'oxydation III et VI du chrome à l'état solide par spectrométrie de masse lamma“. Grenoble 2 : ANRT, 1986. http://catalogue.bnf.fr/ark:/12148/cb375979576.
Der volle Inhalt der QuelleTête, Johann. „Oxydation catalytique du propane en acide acrylique, optimisation des performances en mode pulsé et cinétique de réoxydation“. Compiègne, 2003. http://www.theses.fr/2003COMP1485.
Der volle Inhalt der QuelleThe propane oxidation into acrylic acid is studied on MoVTeNbO catalyst. The application target is a circulating fluid bed reactor (CFB). In this aim, a innovating set up is developed order to simulate the kinetic part of the spatial decoupling. Thus a fixed bed is altemately scanned by oxidant mixture and then by a reducing mix. Ln spite of a qantified effect of relaxation, this temporal decoupling is exaggerated order to authorize different operating conditions between reoxidation and reduction. Moreover several oxidant (or reducing) pulses are successively injected. By this means, it is possible to follow the performances versus the oxidation state of catalyst. The performances are optimised thanks to several studies on the parameters such as the relative pressure of oxygen, the temperature of reoxydation,. . . But a precise oxidation state winch enables optimal catalytic performances is defined. Before this irreversible degradation of the activity of the catalyst is observed. Beyond this, the formation of MoO3 is supposed and conducts to irreversible transformation of the catalyst and its properties. In this optimal state, another irreversible degradation could be observed : a decrease of the selectivity when reduction during one cycle is to high. The omnipresence of tins potential degradation explains the poor performances aunced a lot of papers on the same MoVTeNbO catalyst. Moreover and spite of few publications on the subject, an activation under oxidant atmosphere is proved and is in fact the most important recommended outlook. Finally a kinetic model is proposed for the reoxydation. It shows two different catalytic sites, the first is selective and the second favours combustion
Cachia, Jean-Nicolas. „Solubilité d'éléments aux degrés d'oxydation III et IV dans les verres de borosilicate : application aux actinides dans les verres nucléaires /“. [Gif-sur-Yvette] : [CEA Saclay, Direction des systèmes d'information], 2006. http://catalogue.bnf.fr/ark:/12148/cb409352592.
Der volle Inhalt der QuelleAtinault, Elodie. „Etude de l'oxydation radiolytique de l'uranium de degré d'oxydation +IV par radiolyses pulsée et stationnaire induites par divers rayonnements : hélions, électrons accélérés et gamma“. Nantes, 2008. http://www.theses.fr/2008NANT2121.
Der volle Inhalt der QuelleIn each step of the nuclear fuel cycle, the understanding of effects of ionizing radiations (alpha, beta, gamma) on some matters of which one of elements is uranium (U), has an important physical chemistry role. This work aims to understand the effect of these ionizing radiations on UIV and in particular, on its radiolytic oxidation. This one is inserted in an acidified aqueous solution (HCl) so as to stabilize this very unstable oxidation degree in the presence of O2 and by fixing the ionic strength (NaCl) for an easier comparison of the results. Firstly, the radiolytic oxidation of UIV had been observed during α and γ stationary radiolysis which informs on the overall balance of this reaction by measuring the radiolytic yields of disappearance for UIV and appearance for UVI under different atmospheres. Secondly, a picosecond pulse probe setup connected with the electron accelerator ELYSE had been developed in order to understand the mechanism of the oxidation initiated by low L. E. T particles of which the fastness is due to the high concentration of scavengers. The formation radiolytic yield of the hydroxyl radical HO• had been estimated. From this study, the oxidation mechanism of UIV had been deduced, confirmed then by some simulations. Thirdly, a transient spectroscopy setup linked with a hellion pulse beam had been established for the future adaptation and use on the cyclotron “ARRONAX”. The aim of this work is to prepare the arrival of this cyclotron in order to facilitate its installation and then, begin quickly the study of alpha pulse radiolysis
ZAKI, ABDENASSER. „Synthese, caracterisation et reactivite de composes moleculaires du niobium et du tantale dans les degres d'oxydation (3) a (-1) avec des ligands phosphores et diimines“. Nice, 1991. http://www.theses.fr/1991NICE4484.
Der volle Inhalt der QuelleMartins, Da Silva Fernando Henrique. „Etude structurale, distribution cationique et état d'oxydation dans des nanoparticules magnétiques de ferrite du type coeur-coquille“. Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066102/document.
Der volle Inhalt der QuelleStructural properties of core-shell ferrite nanoparticles MFe2O4 (M = Mn and Co) and Mn-Zn ferrite nanoparticles are here investigated. The nanoparticles are synthesized by hydrothermal co-precipitation and are dispersed in acid medium thanks to an empirical surface treatment by ferric nitrate, which prevents the chemical dissociation by a thin maghemite layer incorporated at the surface of the nano-grains. Chemical titrations allow us to calculate volume fractions of core and shell, as well as the surface-layer thickness. Structural changes induced by the surface treatment are followed as a function of treatment duration in MnFe2O4 and CoFe2O4 nanocrystals. Whereas structural changes in Mn-Zn ferrite nanoparticles are investigated as a function of zinc content. X-ray and Neutron diffractions are used to determine the structural parameters, in particular cationic distribution in the spinel ferrite sites. Precise structural information with high degree of reliability is obtained by Rietveld refinements. To investigate the local structure of these materials, X-ray Absorption Spectroscopy measurements are performed, allowing determining interatomic distances, mean oxidation state and inversion degree. Morphology, crystallinity and size of mixed-ferrite nanoparticles are investigated by TEM/HRTEM and electron diffraction. In Mn-Zn ferrite nanoparticles, the presence of Mn3+ in octahedral environment is responsible for anisotropic distortions, known as Jahn-Teller effect. The inversion degree obtained in this work diverges from the bulk values due to the reduction to nanoscale and to the increase of the surface/volume ratio, associated to the synthesis process
Condamines, Nicole. „Contribution à l'étude de l'extraction d'acides minéraux et de cations actinides aux degrés d'oxydation (IV) et (VI) par des N,N-dialkylamides /“. Saclay : Commissariat à l'énergie atomique, 1990. http://catalogue.bnf.fr/ark:/12148/cb35100410n.
Der volle Inhalt der QuelleAharonian, Ghazar. „Réactivité de dérivés moléculaires du niobium et du tantale dans les degrés d'oxydation IIIàI avec des ligands assembleurs complexes imido et diimines“. Grenoble : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb37593802p.
Der volle Inhalt der QuelleLachaise, Isabelle. „Additions radicalaires amorcées par le manganèse au degré d'oxydation trois formes in situ par voie électrochimique : mécanisme et application à la synthèse de composés cycliques“. Paris 11, 1993. http://www.theses.fr/1993PA112220.
Der volle Inhalt der QuelleRatti, Christian. „Synthèse et étude physico-chimique de porphyrines du titane, de l'étain et du fer : complexes de bas degré d'oxydation, à liaisons métal-carbone et métal-chalcogène“. Dijon, 1988. http://www.theses.fr/1988DIJOS038.
Der volle Inhalt der QuelleAUBRIET, FREDERIC MULLER JEAN FRANCOIS. „ETUDE PAR SPECTROMETRIE DE MASSE DE LA FORMATION DES AGREGATS IONISES INDUITS PAR ABLATION/IONISATION LASER DE COMPOSES MINERAUX. APPLICATION A LA DIFFERENCIATION DES DEGRES D'OXYDATION DU CHROME /“. [S.l.] : [s.n.], 1999. ftp://ftp.scd.univ-metz.fr/pub/Theses/1999/Aubriet.Frederic.SMZ9949.pdf.
Der volle Inhalt der QuelleMve, Ondo Benjamin. „Oxydation chimique de dithiocarbamates métalliques obtention de degrés d'oxydation élevés non usuels Cuivre (III), Nickel (III) et (IV), Cobalt (IV), Fer (IV) et Manganèse (IV)“. Grenoble : ANRT, 1985. http://catalogue.bnf.fr/ark:/12148/cb37594999d.
Der volle Inhalt der QuellePagliarini, Olivio. „Chimie moléculaire du niobium et du tantale dans les degrés d'oxydation IV à II synthèse et réactivité d'alcoxydes du tantale et du bis (cyclopentadiényl) niobium (II) /“. Grenoble 2 : ANRT, 1987. http://catalogue.bnf.fr/ark:/12148/cb376086348.
Der volle Inhalt der QuelleMabad, Bouchra. „Modelisation du site d'oxydation de l'eau en photosynthese : complexes du manganese avec des bases de schiff polydentees“. Toulouse 3, 1987. http://www.theses.fr/1987TOU30103.
Der volle Inhalt der QuelleDarracq, Stéphane. „Contribution à l'étude des corrélations entre stœchiométrie, structure, liaison chimique et propriétés physico-chimiques de perovskites oxygénées renfermant un élément 3d à un degré d'oxydation inusuel (Cu(III), Cu(IV), Fe(IV))“. Bordeaux 1, 1993. http://www.theses.fr/1993BOR10564.
Der volle Inhalt der QuelleDarracq, Stéphane. „Contribution à l'étude des corrélations entre stoechiométrie, structure, liaison chimique et propriétes physico-chimiques de perovskites oxygénées renfermant un élément 3d a un degrè d'oxydation inusuel (Cu(III), Cu(IV), Fe(IV))“. Phd thesis, Université Sciences et Technologies - Bordeaux I, 1993. http://tel.archives-ouvertes.fr/tel-00136172.
Der volle Inhalt der QuelleVillain, Olivier. „Contribution à l'étude de l'environnement structural du chrome dans les verres“. Phd thesis, Université Pierre et Marie Curie - Paris VI, 2009. http://tel.archives-ouvertes.fr/tel-00406764.
Der volle Inhalt der QuelleJung, Duk-Young. „Stabilisation et caractérisation de l'iridium(VI) au sein d'oxydes de structure perovskite : corrélations entre degré d'oxydation, force de la liaison chimique et propriétés des oxydes d'iridium (A,A')MIrn+O6-δ (n = III, IV, V et VI)“. Bordeaux 1, 1995. http://www.theses.fr/1995BOR10552.
Der volle Inhalt der QuelleAbel, Jonathan. „Corrélations compositions chimiques- structures d'oxydes mixtes (Ce/Zr) à base de Pr4+/Pr3+ et propriétés de réductibilité“. Phd thesis, Université Sciences et Technologies - Bordeaux I, 2011. http://tel.archives-ouvertes.fr/tel-00661383.
Der volle Inhalt der QuelleJunker, Michel. „Etude et optimisation des propriétés optiques et morphologiques d'un luminophore du type La1-x-yCexTbyPO4“. Phd thesis, Ecole Nationale Supérieure des Mines de Saint-Etienne, 1995. http://tel.archives-ouvertes.fr/tel-00843196.
Der volle Inhalt der QuelleGossiaux, Alexandre. „Comportement au feu de mousses polyuréthanes rigides : Approches systématiques“. Electronic Thesis or Diss., Centrale Lille Institut, 2021. http://www.theses.fr/2021CLIL0021.
Der volle Inhalt der QuelleA common awareness of environmental factors and more particularly of global warming makes it urgent to better control energy consumption. One solution is to reduce energy loss in building using new and efficient thermal insulation materials such as polymeric foams. Polyurethane (PUR) and polyisocyanurate (PIR) foams are very effective and competitive materials due to their low cost. However, these materials are extremely flammable due to their organic nature. Researchers and manufacturers add molecules called flame retardants (FRs) to their composition in order to prevent the outbreak of a fire or reduce the intensity of combustion when a fire breaks out. The objective of this PhD work is to study by systematic approaches the fire behavior of PUR and PIR foams. The aim is to propose a scientific approach allowing a quicker and more efficient development of new formulations. This systematic study was also coupled with a multi-scale study of the fire behavior of the foams, as a laboratory-scale fire test was developed (M-SBI), which allowed a quick and efficient examination of the formulations. The FRs studied in this work are phosphorus organic FRs which are currently promoted to replace some halogenated FRs which could be dangerous for the environment and health. The mechanisms of degradation of virgin and flame retarded foams were elucidated using various analytical tools. Thus, in the case of phosphorus FRs, we were able to demonstrate that their mode of action varied according to the phosphorus oxidation degree as well as according to their point of decomposition. Moreover, the efficiency of the FRs also varies according to the foam used (PUR or PIR). All these results can thus advantageously be exploited to propose future efficient flame retardants for specific systems to reduce the combustion intensity of the foams
Gouré, Eric. „Réactions de transfert d'amines fonctionnalisées catalysées par des systèmes binucléaires de fer non hémiques : intermédiaires à haut degré d'oxydation“. Phd thesis, 2008. http://tel.archives-ouvertes.fr/tel-00342006.
Der volle Inhalt der QuelleLa deuxième partie de ce manuscrit est dédiée à un complexe binucléaire à fer à valence mixte possédant une branche aniline. En présence de base, ce complexe subit une déprotonation du ligand aniline induisant une inversion de valence des ions métalliques et un changement de couleur de la solution visible à l'œil nu. Cette réaction réversible est le premier cas d'inversion de valence induit par une réaction acido-basique. Ce complexe possède la capacité de détecter des amines en solution organique et en phase solide.