Дисертації з теми "Ions moléculairess"
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Tenanguena, Nongni Fresnelle. "Modélisation de la formation des ions moléculaires dans les plasmas froids de gaz rares." Electronic Thesis or Diss., Université de Toulouse (2023-....), 2024. http://www.theses.fr/2024TLSES080.
Повний текст джерелаMolecular ions, in particular, dimeric rare-gas ions have a very important influence on the behavior of rare gas plasmas used in multiple fields. Therefore, the analysis and understanding of their formation are of great importance for the macroscopic modeling of these plasmas. The main objective of this work is to perform calculations of the rate constants of dimers ion formation in cold plasmas using rare gases as carriers over a wide range of reduced electric fields. To do so we have used mesoscopic data (cross sections) obtained from microscopic data (interaction potentials) for argon to provide reaction rate constants of the formation of Ar_2^+. Further, to perform our calculations we have considered all six lowest-lying electronic states of the Ar_2^+ ions. These six electronic states are classified in two fine structure states of the atomic ion, the ground state (_ ^2)P_(3/2) and the excited state(_ ^2)P_(1/2). A quasi-classical trajectory approach based on the nonadiabatic mean-field dynamics approach and Diatomics In Molecules (DIM) model of the interactions in collision complexes used in preceding studies to calculate the collision cross sections that we will use in the present work. These collision cross sections will feed a Monte Carlo code adapted and optimized for the calculation of auxiliary data such as collision energy distributions which are important to provide averaged, thermal ternary recombination rate constants of ground and excite states of the dimer ion. The ternary recombination rate constants calculated in this way are compared with the experimental measurements and theoretical available in the literature. The results we have obtained, are close to these experimental and theoretical values for selected values of reduced electric fields, E/N = 1, 50, and 100 Td, with standard conditions of temperature T = 300 K and pressure P = 10^5 Pa. Thus, these results are expected to be helpful in tuning cold plasma generators for specific applications
Petrel, Christophe. "Déterminants moléculaires du site de fixation de modulateurs allostériques du récepteur aux ions calcium extracellulaires : pharmacologie et modélisation moléculaire." Paris 11, 2005. http://www.theses.fr/2005PA11T009.
Повний текст джерелаQuaglia, Luca. "Etats électroniques des ions moléculaires multichargés transitoires produits par une impulsion laser femtoseconde intense." Paris 11, 2001. http://www.theses.fr/2001PA112336.
Повний текст джерелаElectronic states of transient multicharged molecular ions produced by an intense femtosecond laser pulse are studied using different experimental and theoretical techniques. Highly excited states are investigated in the 101̂7 W/cm2̂ laser intensity range with the help of fluorescence spectra of multicharged atomic fragments coming from the molecular explosion. These measures show the existence of highly excited multicharged molecular ions in a straightforward way. The production, efficiency of these highly excited ions strongly depends on the initial electronic configuration. Low excited states studies are based on fragmentation kinetic energy release spectra in the 101̂5-101̂6 W/cm2̂ laser intensity range. These spectra are analyzed with the help of calculations of potential energy curves of multicharged molecular ion electronic states. For the fragmentation of N2 and O2 molecules, the comparison of experimental and theoretical results shows the existence of several low excited states of the corresponding molecular ions and allows to explain the fragmentation energy release of (N2) ̂4+ and (O2)4̂+ ions without resorting to any stretching of the molecule during the multiple ionization process. Population of highly excited states is studied using a two-pulse experimental set-up based on the fragments emission anisotropy. The origin of this anisotropy is experimentally investigated and interpreted with the help of a Thomas-Fermi bidimensional model of the laser-molecule interaction. Pump-probe experiments show that the population of highly excited states is negligible in the 5x101̂5 W/cm2̂ laser intensity range. The fragments emission anisotropy is due to a very fast re-orientation of the molecular system. Theoretical calculations show that re-orientation takes place during the multiple ionization process and Coulomb explosion and gets faster as the laser intensity is increased
Silva, Jr Humberto da. "Structure et dynamique des ions moléculaires froids : processus de formation et de destruction." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS401/document.
Повний текст джерелаThe work sheds light on the mechanisms, and their efficiency, for (i) formation, (ii) destruction and (iii) internal cooling of cold molecular ions by inelastic ultracold collisions, such as those studied in hybrid setups merging an ultracold atom trap and a laser-cooled ion trap. We have carried out a systematic and consistent analysis of light assisted binary collisions of many relevant atom/ion pairs using accurate effective core potential based quantum chemistry calculations. Radiative association is predicted to occur for all systems with a cross section two to ten times larger than the competitive channel of radiative charge transfer. Partial and total rate constants are also calculated and compared to available experiments. Narrow shape resonances are expected, which could be detectable at low temperature with an experimental resolution at the limit of the present standards. Vibrational distributions are also calculated, showing that the final molecular ions are not created in their internal ground state level. Once light-assisted formation of molecular ions is probed, we have checked their effective radiative lifetime due to the presence of several lasers in the experiments, which turns out to efficiently photodissociate the created ions. Moreover, besides an extremely slow internal relaxation due to the presence of a permanent electric dipole moment, at reasonably time scales, we have found evidences for the population of molecular levels being strongly influenced by collisions with surrounding ultracold atoms. We have further investigated the internal cooling of both H₂⁺ and Rb₂⁺ (with the respective isotopologues) in collisions with ultracold He and Rb atoms, respectively, due to their relevance for experimental implementations. We have described the calculation of the interaction potentials needed to obtain the coupling potential matrix elements used in a multichannel close coupling formalism. In particular, it is shown that the sum of the He-H₂⁺ state-to-state cross sections (with and without vibrational effects) accounting for the coupling between electronic spin and molecular rotation is dynamically equivalent to directly treating the collision problem of a molecular ion as a structureless spherical rotor interacting with the He atom. The additional difficulties of a close-coupling treatment for an effective internal cooling of sympathetically cold Rb₂⁺ ions in collisions with Rb atoms are discussed along the following lines: (i) the homonuclear nature of the problem, inducing trap losses from reactive collisions; (ii) the higher density of internal states due to the heaviness of the system; and, (iii) its long-range neutral-charged interaction. Nevertheless, strong evidence of an efficient internal cooling by inelastic collisions with Rb atoms is found, and may indicate a general trend for all similar heavy species currently found in hybrid trap experiments
Gargaud, Muriel. "Transfert de charge entre ions multichargés et hydrogène atomique (et moléculaire) aux basses énergies (thermiques jusqu'à quelques KeV/nucléon) : aspects théoriques." Bordeaux 1, 1987. http://www.theses.fr/1987BOR10550.
Повний текст джерелаTazi, Sami. "Description moléculaire des ions aux interfaces argile-eau." Paris 6, 2012. http://www.theses.fr/2012PA066471.
Повний текст джерелаIn the context of the geological disposal in clay-rich formations of long-lived nuclear waste, it is necessary to understand and quantify the transport and retention of radionuclides in clays. Molecular simulations have greatly contributed to understand the different mechanisms involved, including the competition with naturally occurring species. However its contribution has so far been somewhat limited to the case of simple ions, which are in general monovalent. The study of the multivalent ions on the surface of clays has been hindered by the lack of reliable polarizable force fields for clays. Indeed, multivalent ions being strongly polarizing, induction effects cannot be neglected to study them at interfaces. In this context, we have developed a polarizable force field for clays, from an original method relying on ab initio calculations only. We present here this method and its application to ion-water and intra-clay interactions. We then validate the force field for the ion-water interaction on static, dynamic and thermodynamic properties, and the intra-clay interactions on static properties. We further illustrate the interest of the polarizable force field by validating it on IR spectra. A second challenge for the lateral surfaces of clays is the necessity to determine the protonation state of the silanols and aluminols clay edge site, which play a fundamental role in the sorption of ions on these surfaces. To address this point we calculate the different pKa values from an original method inspired by the Marcus theory and that rely on thermodynamic integration. In conclusion, the newly developed force field and the knowledge of the different protonation states of the clay edge site will allow the study of the transport and retention of the multivalent ions on clay surfaces
Nana, Ngassam Valéry. "Collisions électrons-ions moléculaires : états résonnants et dynamique de dissociation." Paris 11, 2004. http://www.theses.fr/2004PA112284.
Повний текст джерелаDissociative recombination and related processes are specially effective in interstellar media where the very low density and temperature favour exothermic reactions. They also play an important role in various types of “cold” plasmas. This work reports the study of dissociative recombination of H2+, Ne2+ and HCNH+ molecular ions. The molecular states and their mutual interactions (for Ne2+ + e- and HCNH+ + e- systems) are calculated by ab initio methods: CI calculations for the bound part of the energy spectrum and electron-molecule scattering within the framework of the complex Kohn variational method for the continuous part. The low-energy dynamics (H2+ et Ne2+) is then treated by the multichannel quantum defect method. Several extensions of the formalism were developed in order to take account of the “off the energy shell” effects and to explicitly include the non-adiabatic couplings of the Rydberg states open to dissociation either between them or with the ion continuum
Trasobares, Sánchez Jorge. "High frequency electronics on nanodot molecular junctions : interaction between molecules, ions and waves." Thesis, Lille 1, 2015. http://www.theses.fr/2015LIL10168/document.
Повний текст джерелаAn attractive combination of self-assembled monolayers on top of “Au” single crystal Nanoparticles (AuNp) and Scanning Probe Microscopies permits to explore the interaction between active molecules in the junction, as well as with the media. At the same time, we demonstrate the experimental proof of a molecular rectifying diode working at gigahertz frequency. Device fabrication by fast e-beam lithography allows their characterization by techniques that may need millimeter scale surfaces as well as by near field Scanning Probe Microscopies. Detection of a little number of molecules per AuNP promises interesting future research in the challenge of grafting and detecting single molecules per nanoparticle. On the one hand, this investigation confirms a recent theoretical prediction that cooperative effects between molecules may have an effect on the asymmetry of the conductance histogram line shape. On the other hand, established electrochemical theories are exploited to investigate similar factors such as interaction between redox molecules and the modification of the energy level of molecular orbitals. This study permits extracting a range of coupling energies between molecules that may be a first step towards the quantitative experimental estimation of this key parameter in molecular electronics. Thanks to an AFM connected to Network analyzer, we characterize a molecular diode operating at high frequency to 18 GHz with a rectification ratio of 12 dB (factor 4) at this frequency. Small capacitances in the order of few aF permit to see this behavior at high frequencies
Lacroix, Pascal G. "Composés moléculaires conducteurs et magnétiques." Paris 11, 1989. http://www.theses.fr/1989PA112062.
Повний текст джерелаThis thesis reports on the synthesis and the physical properties of molecular materials containing both magnetic units (binuclear copper complexes) and organic conductors (TCNQ). In order to achieve an effective interaction between magnetic electrons (copper ions) and conducting ones (TCNQ stacks), we have built molecular composites in which magnetic and conducting units are present, with partial charge transfer from TCNQ to copper ions. The electronic structures of these materials have been studied with the help of magnetic (EPR spectra and magnetic susceptibility measurements) and electrical (conductivity) properties. Three kinds of materials have been found depending on the amount of charge transfer : the first one corresponds to systems where no charge transfer occurs, the second one to partial charge transfer and the third one to reduced copper(I) complexes. The case of partial transfer is the most interesting ; in this type of materials, copper(II) and copper(I) ions coexist. The materials belonging to this class are highly conducting. Intercalation of TTF molecules in two-dimensional phospho-chalcogenides of manganese and cadmiun has been achieved. Those intercalated phases exhibit interesting magnetic and conducting properties
Collet, David. "Spectroscopie laser haute sensibilité des ions moléculaires en phase gazeuse : étude des ions N2+, Cl2+ et HBBr+." Lille 1, 2000. https://pepite-depot.univ-lille.fr/RESTREINT/Th_Num/2000/50376-2000-278.pdf.
Повний текст джерелаJonchière, Romain. "Solvatation supercritique de métaux précieux : apports de la simulation moléculaire." Paris 6, 2013. http://www.theses.fr/2013PA066103.
Повний текст джерелаDespite the vast economic interest it attracts, precious metal transport through hydrothermal fluids is still not well understood, and crucially depends on the species present in solution. In this thesis, we use ab initio molecular dynamics to study the solvation of gold and silver as monovalent ions. After studying the correction of dispersion forces necessary to model water, the most common geological solvent, we have dedicated ourselves to modelling of hydrothermal fluids, gradually increasing the system’s complexity. Thus, we could characterise H2O/CO2 systems in supercritical conditions, identify new complexes and interpret experimental EXAFS signals by studying gold hydrosulphide and silver chloride complexes; and finally observe how CO2 influences the solvation of our metallic ions
Gourmala, Chafika. "Synthèse et modélisation moléculaire d'oligosaccharides d'intérêt biologique." Paris 7, 2006. http://www.theses.fr/2006PA077105.
Повний текст джерелаLewis x is a carbohydrate which presents in the polar head of some qlvcolipides. Former studies show that there is molecular recognition between two trisaccharides Lewis x In the presence of calcium. Our ambition is to determine with precision the groups hydroxyls implied in this recognition under the mediation of the calcium. The first part of this work relates to the synthesis of oliqosaccharides and more specificallv the svnthesis of the trisaccharide Lewis a and trisaccharides Lewis x deoxvgenized in various positions of the galactose unit and the description of the mechanisms of reactions. The second part relates to theoretical calculatlons usinq molecular dynamics in water. These calculations are done with an aim of determining the phvsicochemical properties and also of understanding the intermolecular interactions between the two trisaccharides Lewis x and specifically the sites responsible for this interaction in the presence of the ion calcium
Masion, Armand. "Chimie moléculaire et colloïdale des complexes organiques de l'aluminium III partiellement hydrolysés." Vandoeuvre-les-Nancy, INPL, 1993. http://www.theses.fr/1993INPL028N.
Повний текст джерелаDweik, Jalal. "Modélisation moléculaire du transfert membranaire." Montpellier 2, 2008. http://www.theses.fr/2008MON20188.
Повний текст джерелаThe aim of this thesis is to better understand the physical and physicochemical phenomena involved in nano-confined aqueous solutions, especially the role of "solute-solute" and "solute-interface" interactions within nanopores. By a fundamental approach based on the meso- macroscopic physics of fluids, we study the ionic transport across the membrane pores using the “space charge model”. This model based on the nonlinear Poisson-Boltzmann “mean field theory”, takes into account the electrostatic interactions between the membrane and ions in solution. Understanding of Ionic transport and selectivity across nanofiltration membranes is only partial at this level of description. We therefore go beyond the meso and macroscopic approaches by performing "Molecular Dynamics" simulations, a method particularly well adapted to the nanoscale. We focus on a study of “Water/vapour” interfaces and “Water/nanopore” systems, more particularly effects due to the specific characteristics of molecules and ions: size, charge, polarizability. We study the distribution of the ions and molecules and their correlations/fluctuations. Our simulations reveal the important role played by atomic and ionic polarizability on the distribution of ions in aqueous solutions near interfaces and in nanopores. This effect may be at the origin of the filtration selectivity of nanoporous membranes for ions of the same charge valence and therefore must be better understood before being reliably integrated into mesoscopic theories of membrane transport
Naban-Maillet, Jessie. "Energie interne et dissociations d' espèces moléculaires monochargées et de leurs adduits produits sous AP-MALDI : application à la détection d'agents chimiques." Paris 6, 2006. http://www.theses.fr/2006PA066302.
Повний текст джерелаPanten, Dietmar. "Spectroscopic properties of degenerate electronic states in negative ions." Université de Marne-la-Vallée, 2003. http://www.theses.fr/2003MARN0148.
Повний текст джерелаOuaskit, Saïd. "Recherche d'effets de sillage sur la charge de fragments issus de la dissociation dans une feuille mince d'ions moléculaires rapides." Lyon 1, 1986. http://www.theses.fr/1986LYO10036.
Повний текст джерелаFocsa, Cristian. "Étude d'ions moléculaires métalliques par spectroscopie laser à modulation de vitesse." Lille 1, 1999. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/1999/50376-1999-63.pdf.
Повний текст джерелаIskandar, Waêl. "Étude des collisions à basse énergie entre ions multichargés et dimères de gaz rare." Caen, 2015. https://tel.archives-ouvertes.fr/tel-01243329.
Повний текст джерелаWithin this thesis, the dynamics of collisions between low energy multi-charged ions and Van-der-Waals dimers is investigated theoretically and experimentally. During the interaction ion/dimer, electrons from the target can be captured by the projectile and produce ionic states of the dimer. These states will then relax into charged fragments via multiple dissociation processes. Experimentally, this study is performed by means of Cold-Target Recoil-Ion Momentum Spectroscopy, a powerful technique which allows the multi-coincidence detection of target ionic fragments and the projectile. Theoretically, the collision dynamics is investigated using a classical calculation based on the Coulombic Over-Barrier Model and adapted to treat diatomic molecules such as dimers. This model has shown good agreement with the experimental results, both in terms of relative production of the different dissociation processes, and in terms of angular dependence of the molecular orientation in respect with the scattered projectile direction. All of this work has finally enabled to provide, for the different processes, the two-dimensional probability maps p(b) in the molecular frame and to highlight a new relaxation mechanism of the molecular ion named Interatomic Coulombic Decay. This relaxation process is electron emitter of very low energy and could have a significant role in the assessment of damage caused by ion impact
Sunyer, Emmanuel. "La diffusion du sodium dans la silice amorphe : étude par dynamique moléculaire classique." Montpellier 2, 2003. http://www.theses.fr/2003MON20063.
Повний текст джерелаPOISSON, Lionel. "Ions métalliques monochargés, solvatés par des molécules d'eau : Collision et Photofragmentation." Phd thesis, Université Paris Sud - Paris XI, 2001. http://tel.archives-ouvertes.fr/tel-00007079.
Повний текст джерелаCalvez, Guillaume. "Synthèse et étude des applications potentielles de matériaux moléculaires à base d'entités hexanucléaires de terres rares." Rennes, INSA, 2009. http://www.theses.fr/2009ISAR0024.
Повний текст джерелаCoordination polymers are infinite compounds made up of metallic centres bound to one another by organic ligands. Rare-earth-based coordination polymers broaden the application field of this kind of compounds thanks to the exceptional magnetic and optic properties of rare earth ions. The goal of the works achieved during this PhD was to be able to use a rare-earth-based polynuclear entity –the octahedral rare earth based hexanuclear entity– as a metallic centre in coordination polymers. The reactivity of the complex has been a problem resulting either in an alteration or in a non-reaction of the octahedral hexanuclear entity. A solution to this problem has been the solvothermal synthesis, which makes it possible to have the complex react in a medium which is less aggressive towards it. A coordination polymer has been obtained and characterised, several proofs show with certainty that it is a coordination polymer containing octahedral hexanuclear entities as metallic centres
Montout, Lory. "Exploration in silico d'une mini spectrine, l'α-actinine : dynamique et interactions". Paris 7, 2011. http://www.theses.fr/2011PA077232.
Повний текст джерелаThe spectrin superfamilly is a large group of cytoskeletal proteins. Although they have very different functions, the members of this family share a surprising level of structural homology and are composed of conserved domains such a spectrin repeats and globular actin binding domains and EF hands. So far, studies have focused on the mechanical properties of 2 to 3 repetitive units of spectrin or the rod domain of the alpha-actinin, regardless the potential role of the globular domains. In this thesis work, the mechanical model of the entire alpha-actinin was examined. Initially, a hierarchical study by normal modes analysis of the central domain of the alpha-actinin was performed to evaluate the effect of the 3D organization of the repeats on the mechanics of the system. The development of a specific analysis tool allowed us to finely characterize the nature of movements. The impact of the globular domains on these mechanical properties was also explored. In the second part of this work, the influence of ion concentration on the flexibility of the rod domain was discussed. We thus show that : the structural characteristics of the rod domain give it its unique mechanical properties, and the globular domains alter the mechanical behaviour of the fibre ; the screening of charges on the surface of the rod domain by ions changes its flexibility. This study opens the way to the extrapolation of the mechanical properties of alpha-actinin to the other members of the superfamily of spectrin
Sèche, Edouard. "Potentialisation par capture de neutrons : une étude à l'échelle moléculaire sur l'ADN." Orléans, 2003. http://www.theses.fr/2003ORLE2025.
Повний текст джерелаCavalieri, Sylvain. "Dopage avec ions simples et complexes de couches d'arséniure de gallium épitaxiés par jets moléculaires." Nice, 1986. http://www.theses.fr/1986NICE4041.
Повний текст джерелаVallée, Fabienne. "Étude de l'état des produits formés dans des réactions de recombinaison dissociative électrons-ions d'intérêt atmosphérique : N⁺₂ +e, O₂⁺ +e, CO₂⁺ + e, H₂O⁺ +e." Paris 11, 1986. http://www.theses.fr/1986PA112278.
Повний текст джерелаSimon, Claude. "Caractérisation de surfaces organiques moléculaires et polymères par SIMS statique : effet de la métallisation." Metz, 1996. http://docnum.univ-lorraine.fr/public/UPV-M/Theses/1996/Simon.Claude.SMZ9639.pdf.
Повний текст джерелаStatic SIMS (secondary ion mass spectrometry) is a very powerfull technique, allowing the analysis of the uppermost layers of a sample surface. Monolayers and multilayers of molecular and polymeric organic samples, prepared on metal substrates, are analyzed by static SIMS in order to determine the parameters that are responsible of the formation of main mass spectrum peaks. The influence of the metal substrate, as well as the metallization effect, are studied. On bulk polymers, silver metallization allows an increase of the accessible mass range, and detection of ions arising from cationization of polymer fragments by the metal. Finally, a study of surface oligomers is realized by static SIMS
Joinet, Angélique. "Production de faisceaux d'ions radioactifs chimiquement réactifs par séparation en ligne." Paris 11, 2003. http://www.theses.fr/2003PA112163.
Повний текст джерелаThe isotope separation on line method allows to produce by spallation, fragmentation or fission reaction, radioactive ion beams far from the valley of stability. A thick target is irradiated by a high intensity primary beam. Therefore, high production can be achieved. The problem is to find target material that releases rapidly at high temperature, the reaction products stopped into the target. This radiochemical method, optimised to work with an ion source, is based on the thermochemical properties as vapour pressure, diffusion and desorption. The delay due to the mass transfer will have some consequences on the production efficiency, and particularly for the short half life isotopes. This technique has been inefficient for the 14 and 16 group elements, which are chemically reactive in their production environment. The introduction of the chemical evaporation can solve the problem. Chemical specie is introduced into the target, allowing the transportation of the element as a molecule towards the ion source. The neutron deficient selenium and sulphur radioactive ion beams and the neutron rich tin beams are of great interest for the physicist community. The goal of my work has been to optimise the target and ion source unit in order to achieve high intensity and purity. First, off line measurements allowed to find target material dealing to a fast release of these isotopes and of several elements. Afterwards, we studied the formation, stability and ionisation of the COSe, COS, SnS and GeS molecules by on line measurements. One advantage of the chemical evaporation method is to obtaine volatile molecules and to reduce isobaric contamination. This thesis has been done in the frame of the EURISOL project. This would construct a new generation accelerator, that would deliver high intensity and high purity ion beams. And this work demonstrates that a chemical physical treatment of isotopes in their environment is crucial
Legent, Guillaume. "Assemblages moléculaires : modélisation et étude expérimentale par spectrométrie d’émission d’ions secondaires (SIMS)." Rouen, 2007. http://www.theses.fr/2007ROUES048.
Повний текст джерелаThis thesis is in two parts. The first part involves theory and modelling and describes the concept of “functioning-dependent structures” (FDS). These are structures that only last during the time that they fulfil a function and that disappear once they have fulfilled that function. The FDS model is based on the assembly of two Michaelis-Menten type enzymes that are actively catalysing their reactions. We show that FDSs, both in stationary and transient regimes, have emergent properties and can generate new behaviours that cannot be generated by two enzymes not in the form of an FDS (i. E. “free”). The second part involves experiments that are based on the interaction of a beam of ions with the surface of a biological sample. The particles produced, including those produced by atomic recombination, are analysed and imaged using a NanoSIMS 50 (Secondary Ion Mass Spectrometry). We show here using physico-chemical systems and modelling that this technique allows two macromolecules to be colocalised with a precision of around 2 nm
Pouvesle, Jean-Michel. "Réactivité des espèces métastables et des ions moléculaires de l'hélium dans des plasmas a pression élevée." Orléans, 1986. http://www.theses.fr/1986ORLE0216.
Повний текст джерелаBarmaki, Samira. "Ionisation de l'ion moléculaire d'hydrogène H²⁺ en champ laser intense et bref." Bordeaux 1, 2004. http://www.theses.fr/2004BOR12865.
Повний текст джерелаRen, Hua. "Aspects moléculaires des hélicases de la famille de RecQ." Phd thesis, École normale supérieure de Cachan - ENS Cachan, 2009. http://tel.archives-ouvertes.fr/tel-00448084.
Повний текст джерелаTinti, Fabrice. "Interaction à longue distance entre ions cuivre(II) : systèmes binucléaires à pont étendu." Paris 11, 1987. http://www.theses.fr/1987PA112072.
Повний текст джерелаWe study the molecular antiferromanetism in binuclear copper (II) complexes with extended bridging ligand where the distance between the two paramagnetic ions is over 6 A in length. Two problems are to be solved: - is it possible to detect an interaction for which there is a maximal distance between the two copper (II) ions? - Which is the most efficient molecular system for transmitting interactions between two distant metal centers for a given geometry and a given length? Among the physical methods which permit the study of weak interactions between paramagnetic centers (which we delineate), we have used magnetic susceptibility measurements and ESR. Our results extend through three series of complexes where the bridging ligands are carboxylic acids, aromatic diamines and dihydroxyquinones. In each serie, we vary systematically the distance between the copper( II) ions, the enviromental symmetry of the copper(II) ion and of the complexe itself. We thus obtain many examples of coupling observed to be superior then that the coupling of already known compounds with analogous distances. A simple orbital model permits the interpretation of our results
Delaunay, Rudy. "Croissance moléculaire dans des agrégats d’hydrocarbures aromatiques polycycliques induite par des collisions avec des ions." Caen, 2016. https://tel.archives-ouvertes.fr/tel-01640994.
Повний текст джерелаBillebaud, Annick. "Etude expérimentale de l'émission électronique secondaire de cibles minces de carbone sous l'impact de projectiles rapides : ions lourds, ions hydrogène (atomiques, moléculaires, ou sous forme d'agrégats)." Lyon 1, 1995. http://www.theses.fr/1995LYO10170.
Повний текст джерелаSisourat, Nicolas. "Etude théorique de phénomènes d'interférences au cours de collisions atomiques et moléculaires." Paris 6, 2008. http://www.theses.fr/2008PA066369.
Повний текст джерелаLattouf, Elie. "Etude expérimentale de la formation de l’ion d’hydrogène négatif lors de collisions entre un ion positif et une cible atomique ou moléculaire." Caen, 2013. http://www.theses.fr/2013CAEN2075.
Повний текст джерелаThe formation of the negative hydrogen ion (H–) in collisions between a positive ion and a neutral atomic or molecular target is studied experimentally at impact energies of a few keV. The doubly-differential cross sections for H– formation are measured as a function of the kinetic energy and emission angle for the collision systems OH+ + Ar and O+ + H2O at 412 eV/a. M. U. These H– ions can be emitted at high energies (keV) in hard quasi-elastic two-body collisions involving a large momentum transfer to the H center. However, H– anions are preferentially emitted at low energy (eV) due to soft many-body (> 2) collisions resulting in a low momentum transfer. The formation of H– ions by electron capture follows excitation or ionization of the molecule. The molecular fragmentation dynamics is modeled to simulate the emission of H– ions. The overall good agreement between the simulation and the experiment leads to the understanding of most of the experimental observations
Bernard, Christophe. "Etude par dynamique moléculaire de la structure et des propriétés spectroscopiques de verres silicatés dopés par des ions terres rares." Angers, 2000. http://www.theses.fr/2000ANGE0021.
Повний текст джерелаIn the work presented here, we studied the structure and spectroscopic properties of glasses doped with rare earth ions by molecular dynamics. In order to study the links between local structure of the doping ions and spectroscopic properties, we applied a hydrostatic pressure on a na 2o-2sio 2:eu 3 + glass. The pressure acts mainly on the softer structures of the glass, inter-tetrahedral angles and the sodium environment. An increase in eu-o coordination is also observed, from 7. 17 at room pressure to 8. 00 at 20 gpa. As the structural changes observed by simulation remain small, the changes in the spectroscopic properties of europium partially reproduce the changes observed experimentally. We also analysed the sio 2-geo 2:eu 3 + glass which is made up of sio 4 and geo 4 units homogeneously distributed in the matrix. The study of the local environment of europium shows that it is preferentially located in the vicinity of germanium. The average eu-o coordination of 6. 35 reflects the presence of two types of majority sites with 6 and 7 first oxygen neighbours. The agreement between the experimental and simulated luminescence spectra validates both the environments determined by molecular dynamics and the method of calculation of the simulated spectrum. Finally, the study of sio 2-tio 2 glass doped with erbium showed that titanium is present as tio 4 tetrahedra distributed homogeneously in the silica matrix. The presence of titanium with five oxygen neighbours is consistent with a sio 2 / tio 2 phase separation that could be observed at higher titanium concentration
Molina, John Jairo. "Multi-scale modelling of ions in solution : from atomistic descriptions to chemical engineering." Paris 6, 2011. http://www.theses.fr/2011PA066363.
Повний текст джерелаIons in solution play a fundamental role in many physical, chemical, and biological processes. For industrial applications these systems are usually described using simple analytical models which are fitted to reproduce the available experimental data. In this work, we propose a multi-scale coarse graining procedure to derive such models from atomistic descriptions. First, parameters for classical force-fields of ions in solution are extracted from ab-initio calculations. Effective (McMillan-Mayer) ion-ion potentials are then derived from radial distribution functions measured in classical molecular dynamics simulations, allowing us to define an implicit solvent model of electrolytes. Finally, perturbation calculations are performed to define the best possible representation for these systems, in terms of charged hard-sphere models. Our final model is analytical and contains no free “fitting” parameters. It shows good agreement with the exact results obtained from Monte-Carlo simulations for the thermodynamic and structural properties. Development of a similar model for the electrolyte viscosity, from information derived from atomistic descriptions, is also introduced
Szutkowska, Marta. "Mécanismes Moléculaires par lesquels le pH acide augmente la stabilité de l'ARNm du cotransporteur BSC1." Paris 7, 2007. http://www.theses.fr/2007PA077238.
Повний текст джерелаTransport of NH4+ via the medullary thick ascending limb (MTAL)-specific BSC1 cotransporter is critical for acid excretion by the kidney. Metabolic acidosis enhances mRNA and protein abundances of BSC1. We have shown that acidic pH increases mRNA stability of BSC1 via involvement of the 3'untranslated region (3'UTR). Ç-crystalline (ζ -crys) and HuR are proteins that bind AUUUA motifs (ARE) and protect mRNAs from degradation. Here, we determine the role of the 3'UTR-containing ARE and of ζ -crys and HuR in acid pH- increased stability of BSC1. ζ -crys and HuR were detected by Western Blot and confocal microscopy. BSC1 mutants were generated by deletion of ARE and the abundance of BSC1 WT and mutants mRNAs were quantified by Slot Blot or RT-qPCR. We report: 1 Deletion of 4 out of 6 AREs decreased the stability of BSC1. The most relevant effect was observed for the ARE3 (position: 4350, 86% losing). ARE3 and ARE6 (position: 4491) are responsible for pH effect. 2 ζ -crys is expressed in both MTAL tubules and TAL cells and its abundance is induced by acidic pH. Overexpression of ζ -crys increased the stability of WT but not the mBSC1 Δ 3'UTR mRNA. Moreover, acid pH failed to induce any additional effect on BSC1 in cells overexpressing ζ -crys. RNAi-silencing of ζ -crys resulted in an inhibition of BSC1 expression and acid pH effect. ARE2 and ARE3 are the targets of ζ -crys. 3 HuR is expressed in MTAL and TAL cells, and acid pH stimulates its shuttling from nucleus to cytoplasm. Silencing of HuR inhibited acid pH effect. BSC1 mRNA is co-immunoprecipitated with HuR antibody in purified mRNA /proteins complexes but the interaction of HuR with specific ARE remains to be determined
Nouicer, Rachid. "Processus de Fusion-Fission et Spectroscopie Gamma des Produits Binaires dans les Collisions entre Ions Lourds L'egers (40 < ANC < 60)." Phd thesis, Université de Strasbourg, 1997. http://tel.archives-ouvertes.fr/tel-00805800.
Повний текст джерелаLouvradoux, Thomas. "Spectroscopie à haute résolution de H2+ : production et refroidissement sympathique d'ions piégés." Thesis, Université de Paris (2019-....), 2019. http://www.theses.fr/2019UNIP7168.
Повний текст джерелаThe objective of the project is to perform high-resolution Doppler-free two-photon vibrational spectroscopy on the H2+ molecular ions in order to obtain a direct optical measurement of the electron to proton mass ratio. The H2+ ions must be trapped and cooled but can only be cooled by sympathetic cooling using Be+ laser cooled ions. After a general introduction, the second part of this manuscrit describes ion trapping and presents the linear trap we use to trap H2+ and Be+ ions, as well as the methods used to create Be+ ions either by electronic impact or by photo-ionization of a stream of Be atoms. In the third part we present the state selective H2+ ion source using resonance enhanced multiphoton ionisation (REMPI) with a 303 nm pulsed laser, then we present the state-selected cold molecular ions obtained. In the fourth part we present a model for the resonance enhanced multiphoton dissociation spectroscopy technique that we use in order to detect the transition in H2+. In the fifth part we present the design and realization of the 313 nm laser source for Doppler cooling of Be+ ions. The sixth part presents the observation of Coulomb crystals of Be+ as well as mixed crystals of Be+ and H2+, it also presents the different experimental techniques that allow us to obtain and observe these crystals. The seventh part describes the spectroscopy source at 9,17 µm
Jana, Chandramohan. "Modelling the structure and IR spectra of micro-hydrated ions." Palaiseau, Ecole polytechnique, 2014. https://tel.archives-ouvertes.fr/tel-01120935/document.
Повний текст джерелаIon micro-hydration has been modeled by a combination of classical and quantum methods. The structures, dynamics and IR spectra of micro-hydrated cluster ions ranging from 1 to 216 water molecules have been considered with special emphasis on the comparison to recent experimental data. Quantum modeling has been used to provide reference values against which the polarizable AMOEBA force field could be calibrated. Extension of the parameter set was carried out in some cases, in particular when improvement of the electrostatic and polarization energy terms was deemed necessary. Classical molecular dynamics was then used with two different aims: (1) extensive exploration of potential energy surfaces for large cases with numerous low energy minima, for which statistical sampling is required, and (2) computation of IR spectra through Fourier transform of the Dipole moment AutoCorrelation Function (DACF), at various temperatures. The hydration of Zn2+ was studied in detail. While the coordination number (CN) of zinc cation is firmly established to be six in bulk solution, recent experimental and computation studies in the gas phase have unveiled a complex pattern for small clusters with up to 12 water molecules with a CN more near 5 or maybe even 4. Our calculations, performed from 6 to 216 water molecules, allow a precise description of CN evolution with cluster size. Sodiated tryptamine with one or two water molecules attached was investigated in order to interpret gas phase IR spectra of these species. Particular care was taken of electrostatics - especially atomic charges - and of starting structures in molecular dynamics simulations. It was then possible to investigate temperature-dependent dynamics in detail and to obtain good agreement with IRPD spectra. Finally, the hydration of the sulfate anion with up to 100 water molecules was analyzed focusing on the existence of dangling O-H bonds on the cluster surface as a function of cluster size. In agreement with IRPD experiments, we find that small clusters are compact with no dangling bond. The latter appear when ca. 25 water molecules are present with a characteristic vibrational band. Overall, these results underline the requirements for accurate modeling of ion hydration. These involve refined treatment of electrostatic and polarization interactions, extensive sampling of the potential energy surfaces, careful treatment of cluster boundaries including a confining repulsive wall, and long-time simulations to attain converged radial distribution functions. With such developments at hand, it is now possible to obtain a realistic picture of structures and dynamics of large micro-hydrated cluster ions, as can be judged from the comparison to experiment, especially vibrational spectroscopy
Batat, Pinar. "Communication moléculaire photo-ionique : les études ultrarapides de composés supramoléculaire." Thesis, Bordeaux 1, 2011. http://www.theses.fr/2011BOR14336/document.
Повний текст джерелаUltrafast femtosecond transient absorption measurements (30 fs FWHM pulses) and complementary picosecond spectroscopies (20 ps FWHM pulses, streak camera detection), as well as steady state absorption and fluorescence measurements, were used to study a range of molecules and molecular assemblies. Processes such as intramolecular charge transfer, electronic energy transfer and photoinduced electron transfer were characterized. Amphiphilic azacrown-containing hemicyanine dyes and resulting iono- and photosensitive artificial membranes were studied using Langmuir-Blodgett techniques in the presence of various cations. Among a range of other molecules studied, NIR emitting aza-BODIPY dyes were studied by time-resolved methods in order to investigate their suitability for Photodynamic Therapy applications and imaging. Differently functionalized BODIPY dyes were investigated with respect to photostability, two photon absorption and ion sensing
Bhowmick, Indrani. "Synthèse et caractérisation de matériaux moléculaires magnétiques incorporant des ions métalliques 3d et 4d/5d connectés par des ponts cyanures." Thesis, Bordeaux 1, 2012. http://www.theses.fr/2012BOR14567/document.
Повний текст джерелаIn this thesis, we have synthesised new cyanido bridged heterometallic molecule-based magnetic materials with the tool of simple donor-acceptor coordination chemistry. The 3d metal ion (MnII/III,FeII, NiII, CuII) based molecular precursors acted as acceptor building blocks, whereas the 4d (RuIII)and 5d (ReIV) trans-cyanido type molecular precursors were used as donor moieties.Chapter I contains a theoretical approach with examples of low dimensional magnetic materials:Single Molecule and Single Chain Magnets that illustrate the role of the cyanido ligand to design such magnetic materials. Furthermore, we emphasized the 4d/5d metal based cyanido precursors for their higher magnetic anisotropy over the 3d metal ions. The choice of molecular precursors, their synthesis and characterization were extensively described in chapter II. In this research work, we have obtained many heterometallic molecular complexes and also one dimensional systems. Chapter III, IV and V contain the synthesis, X-ray crystallographic and magnetic characterization of all the newly synthesized complexes. The close crystal packing of the molecules lead to an antiferromagnetic ground state for most of the complexes and this often perturbed the magnetic relaxation phenomena. As expected, we have found metamagnetic phase diagrams for most of these systems. Some of the ReIV/MnIII and a ReIV/FeII one dimensional compounds exhibited Single-Chain magnet like properties and thus magnetic bistability
Marciante, Mathieu. "Dynamique d'ions en pièges radiofréquences." Thesis, Aix-Marseille 1, 2011. http://www.theses.fr/2011AIX10040/document.
Повний текст джерелаRadio-frequency (rf) traps allows one to confine charged particles (atoms or molecules) in a small region of space. These traps, with laser cooling technics, allows one to study and to control matter at the atomic level.In this thesis are shown different results obtained by numerical simulations using molecular dynamics technics. This thesis is formed of four parts. A first part introduce the necessary knowledge to comprehend the ion dynamics in rf traps. The second part present the results from a study on the influence of coulomb coupling on the doppler cooling of trapped ions in a linear quadrupole rf trap. The third part is a study of the properties of ring structures of ions, obtained for low temperatures in linear higher order rf traps. A last part of the thesis is a proposal allowing one to obtain additional rf field-free regions in linear higher order rf traps
Capron, Michael. "Étude de l'interaction entre ions multichargés et systèmes complexes d'intérêt biologique : effets de l'environnement à l'échelle moléculaire." Phd thesis, Université de Caen, 2011. http://tel.archives-ouvertes.fr/tel-00741879.
Повний текст джерелаIndrajith, Suvasthika. "Croissance moléculaire induite dans les agrégats d'hydrocarbures linéaires par la collision avec des ions et des électrons." Thesis, Normandie, 2021. http://www.theses.fr/2021NORMC201.
Повний текст джерелаThe work presented in this thesis concerns the experimental study in gas phase of the collisions between low energy ionizing particles and weakly bonded, neutral clusters of linear hydrocarbons. The purpose of these experiments was to analyze the processes subsequent to the energy and charge transfers during the collision, which are the fragmentation and molecular growth via the formation of covalently bonded molecules forming these clusters. The experimental work in this manuscript has shed light on the respective roles of electronic ionization and the nuclear and electronic stopping powers of projectiles on growth mecanisms within the clusters. To this end, the studies were carried out with low energy ion beams (keV) supplied by GANIL (Caen), which represents the majority of the results presented here, and experiments using electrons were also carried out at the J. Heyrovsky Institute of Chemistry - Physics (Prague, Czech Republic)
Seghrouchni, Samira. "Recherches dans la série des tétraazaporphyrinogènes : modifications structurales et étude dynamique : RMN des complexes de ruthénium (II)." Montpellier 2, 1993. http://www.theses.fr/1993MON20011.
Повний текст джерелаLaurent, Oscar. "Ions et gaz dans les verres de silice : étude dynamique et approches topologiques." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066243/document.
Повний текст джерелаRigidity theory allows to predict the behavior of many properties of glasses with respect to composition, while considering the underlying network as simple mechanical trusses that can be flexible, isostatic or stressed-rigid. Some recent works showed how useful such an analysis can be, either theoretically or experimentally. In the thesis we will use a method to analyse topological constraints from molecular dynamics simulations in order to establish the rigidity of silica systems of interest under various conditions of composition, pressure and temperature. Applying this constraints counting algorithm to radial and angular constraints in soda-lime systems allowed us to establish composition intervals of isostatic properties while giving a novel comprehension of the constraints and the structure surrounding the ions. We later highlight the faint influence of noble gases atoms upon silica when melted in the bulk. That study also allowed us to link dynamical anomalies of silica under pressure to rigidity changes of the network