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Les dispositifs avancés pour la microélectronique intègrent divers matériaux et sont de dimensions nanométriques. Une connaissance précise de leur composition est requise pour améliorer leurs procédés de fabrication et comprendre leur comportement électrique. Le ToF-SIMS est un candidat intéressant, qui souffre cependant des effets de matrice et ne possède pas toujours une résolution spatiale suffisante. Le but de ce travail est de permettre une analyse quantitative et résolue en profondeur de matériaux et structures pour la microélectronique avancée à l'aide d'un ToF-SIMS standard. Cette étude porte sur SiGe, sur des matériaux à haute permittivité, des implants basse énergie et des matériaux organiques. Elle se concentre sur la préparation d'échantillons, l'optimisation des conditions expérimentales et le traitement de données pour mettre au point des protocoles d'analyse originaux dont la précision est évaluée grâce à d'autres techniques de caractérisation de pointe. Ces protocoles permettent d'améliorer la qualité des analyses en termes de résolution en profondeur, de précision et de reproductibilité

There is an increasing awareness in clinical dentistry of the need to better understand the aetiology and management of tooth wear, as increasing numbers of elderly patients are retaining their natural teeth to a stage when they present with extensive wear. In addition, more younger patients are presenting with wear of both primary and permanent teeth. In order to comply with the philosophy of minimal intervention dentistry, clinical management of tooth wear should focus on early detection and prevention before a restorative approach is considered. Fluoride is a commonly used agent in the management of tooth wear, with previous studies showing that it can protect teeth against erosion (at around pH 2.0 and 3.0) and toothbrush abrasion in an acidic environment (at around pH 3.0). However, it does not reduce attritional wear between opposing tooth specimens. Nightguards are commonly used to prevent attritional wear but there is still a need to improve preventive strategies to manage the risk of erosive tooth wear. Previous in vitro studies have shown that a remineralizing agent in the form of CPP-ACP (casein phosphopeptide – amorphous calcium phosphate) can reduce erosion of both enamel and dentine by white wine. A recent study has also highlighted the potential lubricating and remineralizing properties of a CPP-ACP containing paste (Tooth Mousse®, G C Asia Pty Ltd) in reducing dentine wear in both an acidic environment (pH 3.0) and a near neutral environment (pH 6.1). In this context, it is desirable to investigate the effect of CPP-ACP on enamel wear under conditions simulating various clinical situations and to better understand the nature of third-body components at the wear interface. The aims of the present study were: (i) to determine the effect of CPP-ACP on enamel wear under conditions simulating three clinical situations: heavy attrition with gastric regurgitation (at pH 1.2); toothbrush abrasion after an erosive episode (at pH 3.2); and erosion from gastric regurgitation (at pH 1.2), and (ii) to clarify its mode of action by characterizing the enamel surface treated with CPP-ACP. Electro-mechanical tooth wear machines were used to simulate attrition and toothbrush abrasion in combination with erosion, but no machine was used in experiments investigation erosion alone. The effect of paste containing CPP-ACP in reducing erosive tooth wear was also compared with that without CPP-ACP. Enamel surfaces with and without treatment with CPP-ACP were then characterized by using Time of Flight – Secondary Ion Mass Spectrometry (ToF-SIMS). CPP-ACP was found to reduce enamel wear under conditions simulating heavy attrition combined with gastric regurgitation, and toothbrush abrasion after an erosive episode. However, it did not protect enamel from erosion under conditions simulating gastric regurgitation alone, indicating that its lubricating effect was more pronounced than its remineralizing effect. Silicone and ethyl siloxane were present in trace amounts on the enamel surface treated with Tooth Mousse®, thus they were found to be included in its formulation. These findings imply that CPP-ACP nanocomplexes and silicon can act as third body components to lubricate the wear interface. The findings presented in this thesis have implications for clinical management of tooth wear and may lead to new strategies of tooth wear prevention. Although some caution is needed in extrapolating these findings to the in vivo situation, it should be noted that in vitro studies provide valuable insights into separate components of the tooth wear process that are often difficult to distinguish in clinical situations. Overall, this thesis provides new information about the role of CPP-ACP in reducing erosive enamel wear and provides a basis for future experimental and clinical studies focussing on tooth wear prevention. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1379897 / Thesis (Ph.D.) -- University of Adelaide, School of Dentistry, 2009

Les batteries lithium-ion sont largement utilisées comme source d'énergie pour les appareils électroniques portables. L'oxyde de fer (principalement α-Fe2O3), l'un des oxydes de métal de transition les plus important, a suscité l’intérêt scientifique depuis qu'il a été reporté comme matériau d'anode pour les batteries lithium-ion en raison de sa capacité théorique élevée (1007 mAh g-1), de son respect de l'environnement, de son abondance et de son faible coût. Dans cette thèse, une électrode modèle en couche mince d'oxyde de fer a été préparée par simple oxydation thermique à 300 °C dans l'air d'un substrat de fer métallique pur, utilisé aussi comme collecteur de courant. Une variété de techniques d'analyse, électrochimiques (CV, EIS et cyclage galvanostatique), spectroscopiques (XPS, ToF-SIMS) et microscopiques (MEB et AFM), ont été mises en oeuvre pour étudier les mécanismes réactionnels et la chimie de surface de l'oxyde de fer à différents stades de lithiation/délithiation et cyclage. / Lithium-ion batteries (LIBs) are widely used as power sources for portable electronic devices. Iron oxide (mainly α-Fe2O3), as one of the most important transition metal oxide, has attracted attention due to its high theoretical capacity (1007 mAh g-1), environmental friendliness, abundance and low cost since reported as anode material for LIBs. In this thesis, an iron oxide thin film model electrode was prepared by simple thermal oxidation of pure metallic iron substrate at 300 oC in air, also used as a current collector. Electrochemical methods (CV, EIS and galvanostatic cycling) were combined with surface (XPS, ToF-SIMS) and microscopic (SEM, AFM) analytical techniques to investigate the reaction mechanisms and the surface chemistry of the iron oxide thin film at different stages of lithiation/delithiation and upon cycling.

Ce travail de thèse avait pour objectif de développer une méthode basée sur l’étude de la composition isotopique du soufre (δ 34S) permettant de déterminer l’origine, biotique/abiotique, des sulfures de fer au sein des couches de produits de corrosion (CPC). Puis, il s’agissait d’appliquer la méthodologie développée à des systèmes réels afin de déterminer les mécanismes de formation de ces sulfures de fer. Des méthodes d’analyse isotopique du soufre adaptées aux liserés de sulfures de fer micrométriques observés dans les systèmes réels ont été développées en nanoSIMS et ToF-SIMS. L’étude de sulfures de fer formés en milieu carbonaté anoxique en présence, ou non, de bactéries sulfato-réductrice a permis de valider l’emploi de ces méthodes pour la détermination de l’origine des sulfures de fer. L’application de ces méthodes isotopiques couplées à la caractérisation des sulfures de fer dans les systèmes réels a mis en évidence 2 faciès. Le faciès 1 pour lequel les sulfures de fer sont situés en externe de la CPC. Ils résultent de la migration des ions Fe2+ produits au niveau du métal jusqu’aux zones riches en ions S2- d’origine biotique. Les vitesses de corrosion y sont inférieures à 20 μm/an pour les systèmes de laboratoire et à 5 µm/an pour les objets archéologiques. Et le faciès 2 pour lequel la forte présence de phases conductrices dans la CPC entraîne une délocalisation des électrons, conduisant à la migration des ions S2- d’origine biotique vers le métal où ils précipitent sous forme de sulfures de fer. Ce faciès présente de fortes avancées de corrosion locales (200 µm) qui seraient dues à l’accumulation de phénomènes de corrosion par les chlorures et de biocorrosion. / The first goal of this project was to develop a methodology based on the study of the sulfur isotopic composition enabling the determination of iron sulfides origin, biotic or abiotic, within the corrosion products layers (CPL). Then, the aim was to apply this methodology to real corrosion systems in order to determine the mechanisms of iron sulfides formation. Sulfur isotopic analyses methodologies, adapted to micrometric iron sulfides layers observed in real corrosion systems, were developed in nanoSIMS and ToF-SIMS. The study of iron sulfides formed in anoxic carbonated medium with or without sulphate-reducing bacteria validated the use of these methods for the determination of iron sulfides origin. The application of these methods coupled with the precise characterization of irons sulfides formed in the real corrosion systems show two kind of corrosion pattern. In pattern 1, the iron sulfides are localized in the external part of the CPL. They result from the Fe2+ migration from the metal surface to areas rich in biotic S2-. In this pattern, corrosion rates are lower than 20 μm/year for laboratory systems, and lower than 5 μm/year for archaeological objects. In pattern 2, the large presence of conductive phases in the CPL results in the delocalization of electrons, and so a disequilibrium of the charges at the metal’s surface. That leads to the migration of biotic S2- in the CPL till the metal where they precipitate in iron sulphides. This pattern shows high corrosion rates (~100 μm/an) that might be resulting from the accumulation of biocorrosion and chloride corrosion mechanisms.

My dissertation primarily focuses on the fabrication of materials for solid phase microextraction (SPME) and separation devices. In my first project, I used direct current magnetron sputtering (DCMS) to prepare sputtered silicon coatings on fused silica fibers. These fibers were then subjected to the chemical vapor deposition of 6-phenyhexylsilane (6-PH) as a stationary phase. Six different types of fibers were made using two different throw distances (4 cm and 20 cm) and three different silicon thicknesses (0.5, 1.8, and 2.8 µm). These coatings were characterized by time-of-flight secondary ion mass spectrometry (ToF-SIMS), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), spectroscopic ellipsometry (SE), and contact angle goniometry. These SPME fibers were evaluated using gas chromatography (GC). The extraction efficiencies of sputtered, 6-PH-coated fibers were compared to that of a commercial fiber (7 µm PDMS) for polycyclic aromatic hydrocarbons (PAHs). Our 2.8 µm thick sputtered silicon coatings showed competitive extraction of low molecular weight PAHs and ca. 3 times the extraction efficiency for higher molecular weight PAHs. In addition, it outperformed the commercial fiber by showing better linearity, repeatability, and detection limits. A method for analyzing polyaromatic hydrocarbons in baby formula was developed, which showed very good linearity (0.5-125 ppb), repeatability (2-26%), detection limits (0.12-0.81 ppb), and recoveries (103-135%). In my second project, I focused on preparing sputtered carbon SPME fibers using DCMS sputtering. These fibers were tested with and without PDMS coatings on top by SPME-GC-MS. In addition, a new SPME evaluation mix was developed for testing the newly developed SPME fibers. The evaluation mix included analytes with diverse functionalities and properties. Our best carbon fiber showed very competitive extraction capabilities on a per volume basis when compared with a commercial 95 µm carbon-based fiber. In a third project, I built an ALD system to deposit thin films inside GC capillary columns. This system has a unique design that also allows for ALD on witness silicon samples before and after the capillary column. This system yields very promising results with ALD of alumina inside 5 and 12 m long capillary columns. The ALD coatings deposited inside the columns were characterized by transmission electron microscopy (TEM) and energy dispersive X-ray analysis (EDX). The thicknesses of the coatings on witness shards were almost identical to the thicknesses of the coatings in the capillaries. My fourth project focused on characterizing a liquid polymer (diphenyl siloxane dimethyl siloxane (DPS-DMS)) via SE. This material was a potential stationary phase for our SPME fibers. Transmission measurements were obtained via a dual cuvette approach that eliminated the effects of the cuvettes and their interfaces. The optical function of this material was modeled with a Sellmeier function in its transparent region.

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Les travaux présentés dans ce mémoire concernent l’étude des plasmas d’argon créés dans une cavité résonnante micro-ondes fonctionnant à la pression atmosphérique et leur application au nettoyage de surface. Tout d’abord, une étude des enjeux du nettoyage de surfaces industrielles est présentée ainsi qu’un état de l’art des solutions existantes et leurs limitations, mettant en évidence l’intérêt des plasmas comme alternative, notamment ceux fonctionnant en cavité résonnante micro-ondes à pression atmosphérique dont les particularités sont présentées. Dans le cas de l’argon, ces décharges présentent la particularité de ne pas être homogènes mais constituées de un ou plusieurs filaments de faibles diamètres, dépendant des conditions expérimentales. L’étude de la filamentation de ces décharges est l’objet du second chapitre où il a été mis en évidence les corrélations, dans le cas d’un filament unique, entre ses dimensions, sa température et la puissance dissipée et qu’il existait un seuil de puissance au-delà duquel la filamentation apparaissait. Une modélisation électromagnétique simple a été réalisée permettant de décrire l’influence des paramètres principaux de la décharge sur la filamentation. Le troisième chapitre présente les résultats de la caractérisation d’un filament d’argon par absorption laser en plasma continu et pulsé. L’effet de l’addition d’oxygène y est également présenté. Le dernier chapitre concerne l’étude de l’application des post-décharges micro-ondes à la pression atmosphérique créées dans des mélanges argon-azote et argon-oxygène au nettoyage de surface. On y étudie notamment l’interaction de ces post-décharges avec des molécules organiques modèles (acide stéarique et 1-octadécène). L’analyse de surface avec des techniques d’analyse d’extrême surface par spectrométrie de masse (ToF-SIMS et FTMS) a permis d’améliorer notre compréhension des mécanismes de nettoyage / The present work deals with the study of argon microwave plasmas generated in resonant cavity at atmospheric pressure and their application to surface cleaning. First, a study of the aim of surface cleaning of industrial surfaces is presented, followed by a state of the art of existing solutions and their limitations, showing the interest of plasmas as an alternative, especially atmospheric pressure microwave resonant cavity plasmas. In the case of argon, these plasmas have the particularity to be inhomogeneous and constituted of one or many small diameter filaments, depending on experimental conditions. The study of the filamentation of these discharges is the subject of the second chapter. In the case of one filament, correlations have been evidenced between its size, its temperature and the dissipated power. A simple electromagnetic simulation allowed us to describe the influence of the main plasmas parameters on the filamentation process. The third chapter presents results from the characterisation of a single argon filament by the mean of diode laser absorption in continuous and pulsed plasma mode. The effect of oxygen addition is also studied. The last chapter deals with the study of the use of atmospheric pressure microwave post-discharges in argon-nitrogen or argon-oxygen mixtures for surface cleaning application. We studied the interaction of such post-discharges with model organic molecules (stearic acid and 1-octadecene). Surface analyses by the mean of extreme surface analysis techniques based on mass spectrometry (ToF-SIMS and FTMS) allow us to improve our understanding of cleaning mechanisms