A library of 2-nitrobenzenesulfonyl (Ns) derivatives incorporating isotopic labels and a range of structural variations was prepared and characterized to investigate mass spectrometric fragmentation processes. Deprotonated Ns amino acids were formed readily by negative mode electrospray ionization. Collision induced dissociation experiments established precursor-product ion relationships and indicated a novel loss of an aryl ortho substituent (NO2, F, Cl or Br). In total, four distinct fragmentation pathways of Ns-alpha- and Ns-beta-amino acid anions were identified using isotopic labeling, structural variations of the Ns derivatives, and collision induced dissociation of ions generated in source. Overall, the observation of specific fragmentation pathways correlated with anion structure and ionization site. However, the observation of only one of four possible fragmentation processes in the mass spectrum of the Ns derivative of an amino dicarboxylic acid indicated that functional group interactions must also be considered in the interpretation and prediction of fragmentation processes.

The development of the negative ion source constitutes a crucial step in the construction of the neutral beam injector of ITER. To fulfil the ITER requirements in terms of heating and current drive, the negative ion source should deliver 40 A of D-. The achievement of such a source is challenging from technical and scientific points, and it requires a deeper understanding of the underlying physics. The present knowledge of the ion extraction mechanism from the negative ion source is limited due to the complexity of the problem that involves the comprehension of the behaviour of magnetized plasma sheaths when negative ions and electrons are pulled out from the plasma. Moreover, due to the asymmetry induced by the crossed magnetic configuration used to filter the electrons, any realistic study of this problem must consider the three spatial dimensions. To address this problem in a realistic way, a 3D Particles-in-Cell electrostatic code specifically designed for this system was developed. The code uses Cartesian coordinate system and it can deal with complex boundary geometry as it is the case of the extraction apertures. The complex magnetic field that is applied to deflect electrons is also taken into account. This code, called ONIX, was used to investigate the plasma properties and the transport of negative ions and electrons close to a source extraction aperture. Results on the formation of the plasma meniscus and the screening of the extraction field by the plasma are presented here, as well as negative ions trajectories. Negative ion extraction efficiency from volume and surfaces was investigated showing the capital importance of the surface negative ion production.

Le développement de la source d'ions négatifs pour l’injecteur de particules d’ITER constitue une des étapes essentielles pour générer des neutres de haute énergie . Pour remplir les caractéristiques requises pour ITER en termes de chauffage et de courant à l'intérieur du réacteur principal, la source d'ions négatifs doit délivrer 40A de D-. La création d'une telle source représente un défi tant technique que scientifique et demande une meilleure compréhension des phénomènes physiques impliquées . Les connaissances actuelles sur le méchanisme d'extraction d'ion négatifs d’un plasma électronégatif sont limitées, spécialement concernant la compréhension des caractéristiques d'une gaine de plasma magnétisé dans la région d’intérêt où on constante également l’extraction des électrons simultanément avec les ions négatifs qui. De plus, l'asymétrie due à la configuration croisée du champ magnétique pour piéger les électrons nécessite une étude du problème en trois dimensions. Un code 3D Particle-In-Cell électrostatique a été spécialement développé pour étudier ce problème. Le code utilise les coordonnées cartésiennes et peut prendre en compte des géométries complexes. Le code nommé ONIX étudie les propriétés du plasma et le transport des électrons et des ions négatifs au niveau de la zone d'extraction. Les résultats sur la formation d'un ménisque de plasma et l'écrantage du champ d'extraction par ce plasma, ainsi que les trajectoires des ions négatifs, sont présentés. L'efficacité de l'extraction d'ions négatifs du volume et de la surface est investiguée et on trouve que les processus de création en surface des ions négatifs jouent un rôle capital. / The development of the negative ion source constitutes a crucial step in the construction of the neutral beam injector of ITER. To fulfil the ITER requirements in terms of heating and current drive, the negative ion source should deliver 40 A of D-. The achievement of such a source is challenging from technical and scientific points, and it requires a deeper understanding of the underlying physics. The present knowledge of the ion extraction mechanism from the negative ion source is limited due to the complexity of the problem that involves the comprehension of the behaviour of magnetized plasma sheaths when negative ions and electrons are pulled out from the plasma. Moreover, due to the asymmetry induced by the crossed magnetic configuration used to filter the electrons, any realistic study of this problem must consider the three spatial dimensions. To address this problem in a realistic way, a 3D Particles-in-Cell electrostatic code specifically designed for this system was developed. The code uses Cartesian coordinate system and it can deal with complex boundary geometry as it is the case of the extraction apertures. The complex magnetic field that is applied to deflect electrons is also taken into account. This code, called ONIX, was used to investigate the plasma properties and the transport of negative ions and electrons close to a source extraction aperture. Results on the formation of the plasma meniscus and the screening of the extraction field by the plasma are presented here, as well as negative ions trajectories. Negative ion extraction efficiency from volume and surfaces was investigated showing the capital importance of the surface negative ion production.

Le cœur du travail de notre groupe est l'étude de la réaction de photodétachement, qui consiste en l'expulsion de l'électron excédentaire d'un ion négatif lors de l'absorption d'un photon. Ce travail de thèse s'articule autour de deux projets : la microscopie de photodétachement, technique d'interférométrie électronique permettant de produire des données spectroscopiques sur les ions négatifs ; et le projet SIPHORE qui envisage la neutralisation d'un jet rapide d'ions négatifs à partir de la réaction de photodétachement, dans le but de servir la maîtrise de la fusion thermonucléaire contrôlée. Les évolutions de ces deux projets se recoupent dans la nécessité d'augmenter le nombre d'événements de photodétachement produits en un temps donné. Ce travail a permis d'étudier et de mettre en place différentes techniques expérimentales pour réaliser l'amplification de la réaction de photodétachement. Notre montage nous permet de produire cette réaction dans une zone d'interaction formée par l'intersection d'un jet d'ions et d'un faisceau laser. Nous envisageons d'une part la modification de la section efficace de photodétachement lorsque la réaction est produite en présence d'un champ magnétique, d'autre part l'amplification du flux de photons dans la zone d'interaction par stockage de lumière en cavité optique. Les avancées réalisées ouvrent de nouvelles perspectives sur les études fondamentales et les applications techniques liées aux ions négatifs. / The core of the work of our group is the photodetachment reaction, which consists in the expulsion of the extra electron of a negative ion by the absorption of a photon. This thesis work is organised around two projects: the photodetachment microscopy, an electron interferometric technique which produces spectroscopic data on negative ions; and the SIPHORE project which considers the neutralization of a fast negative ions beam by the help of the photodetachment process, for the purpose of controlled thermonuclear fusion. The evolutions of these two projects are overlapping in the need of increasing the number of photodetachment events produced per unit of time. This work has led to the study and the implementation of several experimental techniques to realise the amplification of the photodetachment reaction. Our setup permits to produce this reaction in an interaction area formed by the intersection of a negative ions beam with a laser beam. On the one hand we investigate the modification of the photodetachment cross section when the reaction is produced under a magnetic field. On the other hand we consider the amplification of the photon flux inside the interaction region using light storage with optical cavities. The results obtained pave the way towards new prospects for the fundamental studies and the technical applications affiliated with negative ions.

Indiana University-Purdue University Indianapolis (IUPUI) / Paper spray is an ambient ionization technique for mass spectrometry that is well-known for its ability to accomplish rapid and sensitive analyses without any need for sample preparation. This work further develops the technique in two major areas: negative ionization and drug screening. Negative ionization has always been an obstacle to electrospray-based ion sources because of its vulnerability to corona discharge, but methods are presented here to both quantify and suppress this electrical phenomenon, thus preventing it from interfering with qualitative/quantitative analyses. The validity of the discharge-suppressing method is demonstrated for both a simple screen of barbiturates and other acidic drugs (Chapter 2) and the detection and quantitation of chemical warfare agent hydrolysis products (Chapter 3). Additionally, a positive ion drug screen is applied to the analysis of postmortem blood samples (Chapter 4), achieving rapid and effective screening of 137 different drugs ranging from pharmaceuticals to drugs of abuse. The performance of this screen is also evaluated by comparing the results of the postmortem samples to those obtained using a more established series of assays. The research contained herein presents strides toward forensic application of paper spray mass spectrometry, especially in disciplines related to forensic toxicology.

Low energy electron (LEE) driven chemistry underpins a wide range of interdisciplinary fields, including radiation biology, redox chemistry, astrochemistry and biomaterial design. A growing interest in the chemistry of LEEs concerns the radiative damage to DNA. Studies have found that LEEs can induce single and double-strand breaks in DNA by forming a negative ion resonance (NIR). These processes are remarkably site-specific and have been utilized to synthesize radiosensitizers, which aid in identifying target cells in hypoxic tumors in radiation therapy. Despite the prevalence of LEE-induced reactions, computational studies of such processes are limited compared to thermal and photochemical reactions. The relative scarcity in computational studies of LEE-induced reactions stems from the difficulties in the theoretical treatment of NIRs. In our work, we report new developments on the application of quantum chemical methods to NIRs. We demonstrate that the combination of approaches developed for resonances with multi reference electronic structure methods enables the computation of various types of NIRs in a single calculation. Additionally, we show that multi-reference methods can also quantify the mixing between NIRs. It is observed that the mixing between resonances can have significant consequences on their lifetimes. We also report the development of a new technique, the continuum remover Feshbach projection operator approach, which uses the conventional methods developed for bound states to characterize resonances. We show that this new approach is straightforward to implement with standard electronic structure packages, it is efficient, and provides promising results. / Chemistry

In this work, the Collision Induced Dissociation under Energy Control method was extended to study the fragmentation of gas-phase biomolecules adenine (H5C5N5) and porphyrin FeTPPCl (C44H28N4FeCl). The population distribution for each dissociation channel has been experimentally determined as a function of the excitation energy of the parent molecular ions at a well-determined initial charge state. In collisions between Cl+ and adenine (Ade) at 3keV, the fragmentation pattern of Ade2+ is dominated by the loss of H2CN+ and the successive emission of HCN. The energy distribution of the parent dications confirms the successive emission dynamics. A specific decay channel is observed, i.e., the emission of a charged H2CN+ followed by the emission of HC2N2. In Kr8+-FeTPPCl collisions at 80keV, parent ions FeTPPCl1+,2+,3+ are observed, along with the corresponding decay patterns. It is found that in the first step the dominant low-energy-cost decay channel is the emission of Cl0 independent of the initial charge state of FeTPPClr+ (r=1-3). For the resulted dication FeTPP2+, the dominant fragmentation channel is the neutral evaporation; for the trication however, the dominant fragmentation channel is the asymmetrical fission. In the case of H+ and F+ impact at 3keV, due to the different reaction windows opened in the two collision systems, different fragmentation patterns are observed. Furthermore, nH2 loss processes are observed. Additionally, the production yield of the negative ion emerged in F2+-Ade collision at 30keV is measured to be about 1% using a new experimental approach.

Cette thèse porte sur l'étude de la production d'ions négatifs (INs) en surface pour des applications à la fusion contrôlée. Les INs formés en surface d'un échantillon dans un plasma d'hydrogène à partir de bombardement par les ions positifs sont collectés et analysés en énergie par un spectromètre de masse (SM). Les fonctions de distribution en énergie des INs (FDIs) que mesure le SM sont différentes de celles émises par la surface f(E, Θ) du fait des modifications de trajectoires et d'énergie induites par la traversée du plasma et du SM. Afin de déterminer la FDI émis par la surface f(E, Θ) en se servant des fonctions de distribution mesurée par le SM f''(E) nous avons développé un modèle qui calcule les trajectoires des ions entre la surface et le détecteur du SM. A partir d'une fonction test f(E,Θ) il est alors possible de calculer f''(E) et de comparer à l'expérience. L'élément critique de cette méthode est le choix de f (E, Θ). Le choix effectué dans cette thèse est la fonction de distribution des neutres calculée par le logiciel SRIM pour les particules pulvérisées et rétrodiffusées lors de bombardement d'une surface dans des conditions similaires aux conditions expérimentales. Les résultats du modèle montrent un bon accord entre les FDIs expérimentales et les fonctions calculées, et valident nos calculs et le choix de SRIM.Dans le but de comparer les mécanismes de production et les rendements des INs, une étude comparative a été réalisée sur différents matériaux carbonés. Les FDIs mesurées présentent la même forme à la température ambiante. / This thesis deals with negative ions (INs) surface production for applications in controlled fusion. Negative ions (NIs) formed at the sample surface from positive ions bombardment in hydrogen plasma are collected and analyzed with energy mass spectrometer (MS). The NI energy distribution functions (NIDF) measured by the MS are different from those emitted from surface f(E, Θ) due to modifications trajectories and energies which result when NI cross plasma and MS. In order to determine the NIDF emitted by the surface f(E,Θ) using the NIDF measured by MS f''(E), we developed a model that calculates the ion trajectories between the surface and MS detector. Then from a test function f(E,Θ) it is possible to calculate f''(E) and compare it to the experimental one. The critical issue is this method is the choice of f(E, Θ). The approach used in this thesis is the neutral backscattered and sputtered distribution function calculated by SRIM software during a surface bombardment similar to the experimental conditions. The model resulting show a good agreement between experimental and calculated NIDF, and validate our calculations and the choice of SRIM.In order to compare production mechanisms and NIs yields, a comparative study on different carbons materials was performed. Measured NIDFs show the same shape at room temperature. This indicates that the mechanisms involved in the NI production and the contribution of these mechanisms in the NIDF are the same for all materials. The best NI yield at low temperature is observed on DLC surface. The highest NI yield for all temperatures is observed on Boron doped diamond (BDD) surface at 400°C.

Ce mémoire présente une étude expérimentale de la fragmentation en phase gazeuse des biomolécules, adénine (H5C5N5) et porphyrine FeTPPCl (C44H28N4FeCl), induite par collision avec des ions à basse énergie. La distribution de population pour chaque voie de dissociation a été mesurée en fonction de l'énergie d'excitation des ions moléculaires parents avec la méthode CIDEC (Collision Induced Dissociation under Energy Control). Dans les collisions entre Cl+ à 3keV et adénine (Ade), le schéma de fragmentation de Ade2+ est dominée par la perte de H2CN+ et les émissions successives de HCN. La distribution de l'énergie des Ade2+ parents confirme la dynamique des émissions successives. Une voie de dissociation spécifique, à savoir l'émission successive de H2CN+ et HC2N2 est observée. Les schémas de fragmentation des ions moléculaires FeTPPCl1+, 2+, 3+ sont étudiés dans des collisions avec Kr8+ à 80 keV. Il est constaté qu’indépendante de l'état de charge initiale de FeTPPClr+ (r=1, 2, 3), la perte de Cl0 constitue la première étape de la chaîne de dissociation, tandis que l’état de charge initiale des molécules joue un rôle important dans les étapes suivantes de la dissociation. Dans les collisions avec H+ et F+ à 3keV, dû à un effet de fenêtre de réaction dans les processus de production d’ions négatifs, des schémas de fragmentation très différents sont observés pour FeTPPCl2+. Grâce à la mesure de l’énergie interne des molécules parents, la perte de nH2 est observée et analysée. De plus, le rendement de production d'ions négatifs, mesuré à environ 1% dans des collisions F2+-Ade à 30 keV, est étudié dans ce travail en utilisant une nouvelle approche expérimentale. / In this work, the Collision Induced Dissociation under Energy Control method was extended to study the fragmentation of gas-phase biomolecules adenine (H5C5N5) and porphyrin FeTPPCl (C44H28N4FeCl). The population distribution for each dissociation channel has been experimentally determined as a function of the excitation energy of the parent molecular ions at a well-determined initial charge state. In collisions between Cl+ and adenine (Ade) at 3keV, the fragmentation pattern of Ade2+ is dominated by the loss of H2CN+ and the successive emission of HCN. The energy distribution of the parent dications confirms the successive emission dynamics. A specific decay channel is observed, i.e., the emission of a charged H2CN+ followed by the emission of HC2N2. In Kr8+-FeTPPCl collisions at 80keV, parent ions FeTPPCl1+,2+,3+ are observed, along with the corresponding decay patterns. It is found that in the first step the dominant low-energy-cost decay channel is the emission of Cl0 independent of the initial charge state of FeTPPClr+ (r=1-3). For the resulted dication FeTPP2+, the dominant fragmentation channel is the neutral evaporation; for the trication however, the dominant fragmentation channel is the asymmetrical fission. In the case of H+ and F+ impact at 3keV, due to the different reaction windows opened in the two collision systems, different fragmentation patterns are observed. Furthermore, nH2 loss processes are observed. Additionally, the production yield of the negative ion emerged in F2+-Ade collision at 30keV is measured to be about 1% using a new experimental approach.

Using multiple theoretical methods, comprehensive calculations are performed to create a new and more comprehensive data set for elastic scattering and related transport cross sections for collisions of (H$^+$ + H), (H + H) and (He$^{2+}$ + H) in the center-of-mass energy frame. In proton-atomic hydrogen collisions, we have significantly updated and extended previous work of elastic scattering, charge transfer and related transport integral and differential cross sections in the center-of-mass energy range $10^{-4} - 10^4$ eV where the multi-channel molecular orbital approach (MO3) is used. For atomic hydrogen-hydrogen collisions, similar updates have been made of elastic scattering and spin exchange differential and integral cross sections, also for the H + H collision the ionization and negative ion formation cross sections are provided in energy range (1-20 KeV) by use of the 'hidden crossing' theoretical framework. For collisions of alpha particles with atomic hydrogen we have computed the elastic scattering cross section in the center-of-mass energy range $10^{-4} - 10^8$ eV. In this case, at the lowest energies where elastic scattering greatly dominates other reaction channels, a single-channel quasi-molecular-orbital approach (MO1) is used. With the opening of inelastic channels at higher energies the multi-channel atomic-orbital, close-coupling method is applied, and at the highest energies considered perturbation theory (the Born approximation) is used. The results are compared with other data available in literature.