Spectroscopie X de Précision sur les Ions Lourds Multichargés et les Atomes Exotiques

In this thesis, we present four experiments designed to study hydrogenlike and heliumlike heavy ions, or exotic atoms. These experiments have been run at the Gesellschaft für Scherionenforchung (GSI) and the Paul Scherrer Institut (PSI).In the first part of this text, we begin with the description of a focusing, curved-crystal spectrometer in transmission geometry, coupled with a microstrip, germanium position-sensitive detector, which diffract X-ray photons in the range 50-100 keV. With this spectrometer, which can be mounted on the GSI accelerator, we will increase, by one order of magnitude, the accuracy on the measurement of the 1s Lamb shift in hydrogenlike uranium ions, in order to test QED in strong coulomb field. Next, we detail an experiment that will soon give a new value of the charged-pion mass with a relative accuracy of 1 ppm. For this one, we perform X-ray spectroscopy of pionic nitrogen, at PSI. The experimental set-up is made up of a cyclotron trap, a spherical Bragg-crystal focusing spectrometer, in reflection geometry, and a CCD, sensitive-position cooled detector. This set-up allows also test QCD and chiral perturbation theory by measurements of radiative transitions of pionic hydrogen.The main subject of the second part is a lifetime measurement of a metastable state in heliumlike gold ions, by Beam Foil Spectroscopy. With this experiment, which provides an important test of relativistic many-body theory, we give, for the first time, an accurate value of the lifetime of this state for an ion with a Z larger than 64.Dans ce travail de thèse, nous présentons quatre expériences, portant soit sur l'étude d'ions lourds hydrogenoïdes ou héliumoïdes, soit sur celle d'atomes exotiques, et qui se sont déroulées au Gesellschaft für Scherionenforchung (GSI) et à l'Institut Paul Scherrer (PSI).Dans la première partie de ce manuscrit, nous décrivons, tout d'abord, un spectromètre à cristal courbe et en transmission, couplé à un détecteur germanium sensible en position. Cet ensemble, dédié à la mesure de l'énergie de photons X entre 50 et 100 keV et qui est destiné à être monté sur l'accélérateur du GSI, nous permettra, dans les années avenirs, de gagner un ordre de grandeur sur la précision de la mesure du déplacement de Lamb du niveau fondamental de l'uranium hydrogénoïde, afin de tester la QED en champ coulombien fort. Ensuite, nous détaillons une expérience qui nous permettra de donner bientôt une nouvelle valeur de la masse du pion chargé avec une incertitude relative de 1 ppm. Elle est basée sur une spectroscopie X de l'azote pionique, effectuée au PSI. Pour celle-ci nous utilisons un montage composé d'une trappe anticyclotronique, d'un spectromètre de Bragg en réflexion, possédant un cristal sphérique et d'un détecteur CCD refroidit. Ce dispositif permet également de tester la QCD et la théorie des perturbations chirales, par une mesure des transitions radiatives de l'hydrogène pionique.La seconde partie est consacrée à une description d'une mesure la durée de vie d'un niveau métastable de l'or héliumoïde, grâce à une expérience de temps de vol, qui se déroule au GSI. Nous donnons, pour la toute première fois pour un Z si élevé, une valeur précise de cette durée de vie, qui constitue un test important de la théorie relativiste à n-corps

Etudes de la stabilité de nano-objets complexes chargés : agrégats et systèmes moléculaires d'intérêt biologique

Since the last 6 years, my main research works focused on i) the Coulomb instabilities and the fragmentation processes of fullerenes and clusters of fullerenes ii) the stability and the reactivity of complex biomolecular systems.Concerning the clusters of fullerenes, which are van der Waals type clusters, we shown that the multiply charged species, obtained in collisions with slow highly charged ions, keep their structural properties but become very good electric conductor!In another hand, with the aim to understand the role of the biologic environment at the molecular scale in the irradiation damage of complex biomolecules, we have study the charge stabilities of clusters of small biomolecules or the dissociation processes of larger nano-hydrated biomolecules. Theses studies are shown that i) specific molecular recognition mechanisms continue to exist in gas phase ii) a small and very simple biochemical environment is enough to change the dynamics of instabilities.Durant ces 6 dernières années, ma thématique principale de recherche s'est d'abord focalisée sur l'étude de la stabilité et des processus de fragmentation de fullerènes et des agrégats de fullerènes, puis dans celle de la stabilité et de la réactivité de molécules ou de systèmes d'intérêt biologique.Un des principaux résultats de ces études concerne les agrégats moléculaires de fullerènes, qui sont en principe des agrégats de type van der Waals, donc faiblement liés et surtout électriquement isolants. Nous avons montré que les espèces stables multiplement chargées, formées suite à des collisions avec des ions lents multichargés, qui ne subissent par ailleurs aucune modification structurelle profonde suite à leur chargement par impact d'ions, deviennent contre toutes attentes de bons conducteurs électriques ! Les autres observations majeures obtenues dans ces recherches sont reliées la compréhension des mécanismes responsables à l'échelle moléculaire, en phase gazeuse, de l'endommagement de systèmes moléculaires d'intérêt biologique, suite à une irradiation avec des ions. Ces études ont notamment montré : d'une part, que certains mécanismes de reconnaissance moléculaire persistent en phase gazeuse, et d'autre part, que même la présence d'un environnement biochimique simplifié modifie fortement la dynamique de l'instabilité de la charge de ces molécules d'intérêt biologique

Spectroscopie X de précision sur les ions lourds multichargés et les atomes exotiques

PARIS-BIUSJ-Thèses (751052125) / SudocCentre Technique Livre Ens. Sup. (774682301) / SudocPARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF

Infrared Study of the Bacterial Autoinducer N-Hexanoyl-Homoserine Lactone (C6-HSL) in the Gas-Phase, Water, and Octanol Solutions

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Ligand-protected gold nanoclusters probed by IRMPD spectroscopy and quantum chemistry calculations

This paper reports an attempt to structurally characterize isolated ligand-protected gold nanoclusters by means of gas-phase InfraRed Multiple Photon Dissociation (IRMPD) spectroscopy compared to quantum chemistry Density Functional Theory (DFT) calculations. The mass-selected kilodalton nanocluster complexes consist of ten or eleven gold atoms that are bound to glutathione or phosphine ligands and are produced by ElectroSpray Ionization (ESI) in the form of multiply charged anions or cations. This study allows us to build some methodology benchmarks for species that are large for IRMPD experiments and that are used for biochemistry applications. These gas-phase results on isolated ions are compared to condensed phase data from Fourier-Transform InfraRed (FTIR) spectroscopy and to theoretical IR spectra that are calculated with two different functional/basis sets, namely B3LYP/6-31G* and M06L/LanL2DZ, at the scaled static harmonic level. Although theoretical calculations are able to reproduce well the experimental IR spectra, the size of such species and the presence of many possible interactions between ligands make difficult a precise assignment among the many possible molecular arrangements

Ionisation and fragmentation of tetraphenyl iron (III) porphyrin chloride induced by slow multiply charged ion impact

International audienceIonisation and ion-induced fragmentation of tetraphenyl iron (III) porphyrin chloride (FeTPPCl) molecules have been studied after slow collisions (v ∼ 0.2 a.u.) with multiply charged ions (O3+, Ar8+). Intact molecules and large fragments are observed in charge states up to q = 4. For q = 1, the intact molecule is the most abundant species, in particular, when projectiles in higher charge states are used. When the internal energy of the singly charged ion is increased by the energy transfer during the collision, the singly charged system de-excites by the emission of a neutral Cl-atom, a free electron or possibly a negative Cl anion. The processes are observed as direct as well as delayed processes on a μs-time scale. For q = 2 to 4 the loss of the Cl-atom and some phenyl groups becomes more likely due to the lower stability and the larger energy transfer. The charge state distribution of atomic fragments is found to be very different, in particular, when Cq+ and Clq+ ions are compared. In the first case mainly singly charged ions are detected, whereas in the second case ions in charge states up to q = 6 are observed with high intensities. These phenomena are discussed in terms of the intramolecular charge mobility

Ligand-protected gold nanoclusters probed by IRMPD spectroscopy and quantum chemistry calculations

This paper reports an attempt to structurally characterize isolated ligand-protected gold nanoclusters by means of gas-phase InfraRed Multiple Photon Dissociation (IRMPD) spectroscopy compared to quantum chemistry Density Functional Theory (DFT) calculations. The mass-selected kilodalton nanocluster complexes consist of ten or eleven gold atoms that are bound to glutathione or phosphine ligands and are produced by ElectroSpray Ionization (ESI) in the form of multiply charged anions or cations. This study allows us to build some methodology benchmarks for species that are large for IRMPD experiments and that are used for biochemistry applications. These gas-phase results on isolated ions are compared to condensed phase data from Fourier-Transform InfraRed (FTIR) spectroscopy and to theoretical IR spectra that are calculated with two different functional/basis sets, namely B3LYP/6-31G* and M06L/LanL2DZ, at the scaled static harmonic level. Although theoretical calculations are able to reproduce well the experimental IR spectra, the size of such species and the presence of many possible interactions between ligands make difficult a precise assignment among the many possible molecular arrangements

IRMPD spectroscopy and quantum chemistry calculations on mono- and bi-metallic complexes of acetylacetonate ligands with aluminum, iron and ruthenium ions

International audienceMetal-ligand cluster ions are structurally characterized by means of gas-phase infrared multiple photon dissociation (IRMPD) spectroscopy. The mass-selected complexes consist of one or two metal cations M3+ (M = Al, Fe or Ru) and two to five anionic bidentate acetylacetonate ligands. Experimental IR spectra are compared with different density functional theory (DFT) calculations, namely PBE/TZVP, B3LYP/6-31G* and M06/6-31+G**. Frequency analysis was also performed at different levels, namely scaled static harmonic, unscaled static anharmonic or with ab initio molecular dynamics simulations at the PBE/TZVP level. All methods lead to simulated spectra that fit rather well with experimental data and the spectral red shifts of several main bands, in the 1200-1800 cm-1 range, are sensitive to the strength of the metal-ligand interaction and to the spin state of the ion. Due to the rigidity of those complexes, first principles molecular dynamics calculations provide spectra similar to that produced by static calculations which are already able to catch the main spectral signatures using harmonic calculations at the B3LYP/6-31G* level

IRMPD spectroscopy and quantum chemistry calculations on mono- and bi-metallic complexes of acetylacetonate ligands with aluminum, iron and ruthenium ions

International audienceMetal-ligand cluster ions are structurally characterized by means of gas-phase infrared multiple photon dissociation (IRMPD) spectroscopy. The mass-selected complexes consist of one or two metal cations M3+ (M = Al, Fe or Ru) and two to five anionic bidentate acetylacetonate ligands. Experimental IR spectra are compared with different density functional theory (DFT) calculations, namely PBE/TZVP, B3LYP/6-31G* and M06/6-31+G**. Frequency analysis was also performed at different levels, namely scaled static harmonic, unscaled static anharmonic or with ab initio molecular dynamics simulations at the PBE/TZVP level. All methods lead to simulated spectra that fit rather well with experimental data and the spectral red shifts of several main bands, in the 1200-1800 cm-1 range, are sensitive to the strength of the metal-ligand interaction and to the spin state of the ion. Due to the rigidity of those complexes, first principles molecular dynamics calculations provide spectra similar to that produced by static calculations which are already able to catch the main spectral signatures using harmonic calculations at the B3LYP/6-31G* level

Probing the specific interactions and structures of gas-phase vancomycin antibiotics with cell-wall precursor through IRMPD spectroscopy

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