Ce mémoire de thèse rapporte deux études de l'interaction d'ions ou d'atomes d'énergie de l'ordre du<br />keV avec des surfaces isolantes lors de la diffusion en incidence rasante.<br />La première partie étudie les processus d'échange de charge au-dessus d'une surface de NaCl. En particulier, le mécanisme de neutralisation des ions S^+, C^+, Xe^+, H^+, O^+, Kr^+, N^+, Ar^+, F^+, Ne^+ et He^+ est déterminé par la mesure de la perte d'énergie en coïncidence avec la détection des électrons. Ces résultats montrent l'importance de la double-capture électronique pour la neutralisation des ions ayant trop d'énergie potentielle pour une capture résonnante et insuffisamment pour un processus Auger. Nous avons également étudié l'ionisation du projectile ou de la surface ainsi que les différents mécanismes de neutralisation de type Auger avec émission de l'électron, population de la bande de conduction ou d'état excité. Lors de la diffusion d'oxygène, nous mesurons un rendement électronique plus élevé en coïncidence avec les ions négatifs diffusés qu'avec les atomes suggérant la formation transitoire au-dessus de la surface de l'ion doublement négatif d'oxygène.<br />La seconde étude porte sur la diffraction d'atomes rapides, un phénomène nouveau observé pour la première fois lors de cette thèse. En raison de la grande vitesse parallèle, la surface apparaît comme une tôle ondulée où les rangées interfèrent. À la manière de la diffraction d'atome thermique le motif de diffraction correspond au potentiel et est sensible aux vibrations. Nous avons pu étudier les potentiels H–NaCl et He–LiF dans la gamme 20 meV–1 eV. Cette nouvelle méthode ouvre des perspectives intéressantes pour la caractérisation de surface.

In this work, the use of modified diamond as an electrode material with superlative physical and electrochemical properties was investigated in a number of electrochemical applications. The surface chemistry of three differing forms of diamond, namely boron-doped microcrystalline diamond, boron-doped diamond powder and detonation nanodiamond powder was modified utilising such strategies as hydrogen plasma treatment, reactive ion plasma etching along with various chemical treatments. The surface and functional properties of the modified diamond electrodes were studied using a wide spectrum of techniques. The electrochemical activity of these materials was concomitantly investigated in order to expand the knowledge of diamond electrochemistry and to establish an understanding of how the surface chemistry of these materials impacts their electrochemical performance. In the first study, the nanostructuring strategies of boron-doped diamond surface with platinum nanoparticles were developed. In particular, two types of diamond nanostructures were produced: one consisting of platinum particles located on the top of diamond nanorods, the other with platinum particles located in the bottom of diamond nanopits. For the first time, the experimental evidence proving the mechanism of the diamond nanostructuring process was reported. The electrochemical activity of these nanostructured diamond electrodes with regard to the electrochemical oxidation of glucose and methanol was investigated. In the second study, the relationship between the surface chemistry of three differing forms of diamond, including microcrystalline boron-doped diamond, boron-doped diamond powder as well as detonation nanodiamond powder, and the electrode fouling in the result of the adsorption processes in methyl viologen and anthraquinonedisulfonate solutions was investigated. The influence of two dissimilar surface terminations: hydrophobic H-terminated and hydrophilic O-terminated on the electrode performance was studied in detail. This work provides a useful insight on the likely reasons for the undesirable adsorption occurrence which may be experienced in many electroanalytical applications that utilise solid and powdered forms of diamond. The third project extends the discussion on the study of the diamond electrodes, modified with detonation nanodiamond and boron-doped diamond powders and investigates the electrochemical behaviour of these materials. In this work, charge transport within the diamond powder films, partition coefficients of different redox mediators along with heterogeneous electron transfer constants were identified. The chemical modification of these electrodes with platinum nanoparticles along with the mechanism of nucleation and growth of the latter were studied. The enhanced electrode performance with regard to methanol electrooxidation reaction was demonstrated. The fourth study investigates the preparation of nickel modified boron-doped diamond electrodes and ascertains the relationship between the surface chemistry of the modified diamond and the associated electrocatalytic performance of nickel nanoparticles in hydrogen peroxide and glucose electrooxidation. The fifth study reports on the development of a novel surface functionalization strategy, based on porphyrin and amide coupling chemistry, which allows the creation of hybrid biomimetic diamond interface that was used as the artificial &beta;-alanine receptor.

Cette recherche examine le processus d'identification de la discipline de Technologie par les collégiens. Cette discipline, dans sa reconfiguration de 1996, présente des caractéristiques en contraste avec les autres disciplines présentes au collège. En effet, en tant que discipline de raisonnement et d'action, les enjeux éducatifs sont centraux et dépassent les seuls savoirs ou savoir-faire. L'orientation générale de ses missions fondatrices fait prévaloir la confrontation directe des élèves avec le monde de la technique, sans détours par les sciences. De plus, elle est composée de deux parties, aux modes de pilotages contrastés : l'une, les « réalisations sur projet », fonctionne sur le mode « processus », l'autre ; la « technologie de l'information », sur le mode « produit ». Aussi, les activités proposées aux élèves au fil de leur parcours scolaire sont diverses et répondent à des visées éducatives variées. Notre objectif est de rendre compte des contenus, des enjeux et des modalités pédagogiques que les élèves repèrent, des caractères qu'ils affectent à cette éducation technologique à partir de leurs rencontres régulières avec cette discipline ainsi que les cohérences d'ensemble qu'ils construisent. En raison des spécificités de cette discipline, nous avons été amené à adopter « un point de vue curriculaire » pour répondre à notre questionnement. Nous avons, ainsi, élaboré notre propre cadre d'analyse et construit des outils méthodologiques qui rendent compte de la figure d'ensemble de la discipline construite par les élèves et de son évolution à travers la diversité des tâches effectuées et des organisations pédagogiques vécues. Afin de rendre compte de ces constructions, nous avons suivi, sur trois années, une vingtaine d'élèves volontaires présentant des caractéristiques individuelles contrastées. Ces élèves ont été interviewés à des périodes régulières afin de rendre compte des évolutions possibles éventuelles de leurs élaborations. Les constructions obtenues se distinguent, selon trois catégories : une première catégorie correspond aux élèves qui repèrent les enjeux spécifiques du curriculum c'est-à-dire la compréhension du monde technique qui les entoure et la découverte de quelques métiers. Ces élèves affectent à cette éducation des modalités d'enseignement coopératif. Une deuxième catégorie, correspond aux élèves qui se focalisent sur des apprentissages de savoir-faire, ou apprécient uniquement des aspects socioaffectifs et perdent ainsi de vue les enjeux attendus. Une troisième catégorie intermédiaire, correspond aux élèves qui composent entre les spécificités des enjeux de la Technologie et les attentes scolaires plus habituelles, davantage centrés sur les acquisitions de savoirs. Cette caractérisation nous a permis de mettre en évidence, aux différentes étapes du parcours suivi, les caractéristiques de la Technologie identifiées par les élèves. Cette démarche pourrait être pertinente, voire nécessaire, pour rendre compte des appropriations des enjeux éducatifs dans des parcours éducatifs qui ne sont pas toujours de forme disciplinaire.

The diploma thesis was dealt with the study of system PP and particular filler, specifically PPH and like a filler was used commercially available CaCO3 (SOCAL P3). This type of filler is declared by the producer as a filler without surface treatment. The submitted thesis had a goal to find and testing the suitable method and methodology for defined surface treatment of the filler. This is the first step for systematic study of influence the various types of adhesive layer on mechanical properties of declared composite. The plasma discharge behind static pressure was used for the surface treatment of the fillers. These fillers were afterwards analyzed by using of sedimentation analysis, infra - red spectroscopy (FT-IR) and scan electron microscopy (SEM). The composites with various volume part of the fillers were prepared in PIB and studied by short-time tests. Regarding to experimental demand there wasn't possible to realize the whole originally intended program i. e. study of influence the different types of adhesive layer, including to form the model for FEM approach. Nevertheless finding and testing the suitable method of surface treatment is completely basic for the others study. The above mentioned method was used in this application for the first time and it is possible to consider this process like an original approach.

The marine current turbine (MCT) is an exciting proposition for the extraction of renewable tidal and marine current power. However, the numerical prediction of the performance of the MCT is difficult due to its complex geometry, the surrounding turbulent flow and the free surface. The main purpose of this research is to develop a computational tool for the simulation of a MCT in turbulent flow and in this thesis, the author has modified a 3D Large Eddy Simulation (LES) numerical code to simulate a three blade MCT under a variety of operating conditions based on the Immersed Boundary Method (IBM) and the Conservative Level Set Method (CLS). The interaction between the solid structure and surrounding fluid is modelled by the immersed boundary method, which the author modified to handle the complex geometrical conditions. The conservative free surface (CLS) scheme was implemented in the original Cgles code to capture the free surface effect. A series of simulations of turbulent flow in an open channel with different slope conditions were conducted using the modified free surface code. Supercritical flow with Froude number up to 1.94 was simulated and a decrease of the integral constant in the law of the wall has been noticed which matches well with the experimental data. Further simulations of the marine current turbine in turbulent flow have been carried out for different operating conditions and good match with experimental data was observed for all flow conditions. The effect of waves on the performance of the turbine was also investigated and it has been noticed that this existence will increase the power performance of the turbine due to the increase of free stream velocity.

Ce mémoire de thèse présente le développement d'un dispositif expérimental spécialement conçu pour l'étude de la diffraction d'atomes rapides et son utilisation pour suivre la croissance de couches minces sur un bâti d'épitaxie. Des études de surfaces de KBr(100) et de NaCl(100) avec ce nouveau dispositif sont présentées. Nous nous sommes intéressés notamment à la forme du potentiel que les atomes perçoivent lorsqu'ils diffusent sur une surface de KBr(100). Nous avons également mis en évidence lors de ces études un nouveau régime de diffraction qui semble correspondre à des mouvements longitudinaux et normaux cohérents. Grâce à des images mieux résolues, nous avons montré comment la diffraction d'atomes rapides permet d'observer et quantifier des défauts topologiques comme la mosaïcité. Une étude d'une surface d'Argent (110) est aussi présentée. Elle a permis d'observer la diffraction d'atomes rapides sur les métaux, montrant ainsi que GIFAD est applicable aux trois types de matériaux (isolants, semi-conducteurs et métaux) et que les processus d'excitations électroniques sur ces surfaces ne détruisent pas complètement la cohérence. Enfin des premiers résultats de GIFAD en tant que technique de suivi de croissance par épitaxie sont présentés dans ce travail.

Beton wird global als Werkstoff eingesetzt, weist als Natur-verwendendetes Material allerdings unterschiedliche regionale Spezifikationen auf. Hier entsteht ein Spannungsfeld zwischen Universalismus und Partikularismus. Die beim Absäuern offengelegten Sandkörner werden zum ortsbezogenen Naturpigment, die diese Ambivalenz sinnlich erfahrbar machen. Die Werkgruppe präsentiert in ihrer Uniformität ein Bild der Gemeinsam- und Verbundenheit. Gleichzeitig erheben die einzelnen Platten Anspruch auf spezifische, in ihrer Körnung auf partikularer Ebene abgebildete Eigenschaften der Diversität und Einzigartigkeit.

The method of introduction of metals to nanopowder, and made on their basis of compacts - impregnation in solution which contains necessary impurity is studied. This method is simple and effective, and also allows to vary the maintenance of a dopant in material. Microphotos of a surface of the studied samples are received on the scanning electronic microscope of Zeiss Sigma VP. The analysis of fragments of structure of solid bodies is made on the specialized software of SIAMS 700 (SIAMS Photolab complex). The average size of particles ceramics aluminum oxide with the entered metals was measured in work and distribution by the sizes is constructed. / Изучен метод допирования нанопорошков и изготовленных на их основе компактов - пропитка в растворе, который содержит необходимую примесь. Данный метод прост и эффективен, а так же позволяет варьировать содержание допанта в материале. Микрофотографии поверхности исследуемых образцов получены на сканирующем электронном микроскопе Zeiss Sigma VP. Анализ фрагментов структуры твердых тел выполнен на специализированном программном обеспечении SIAMS 700 (комплекс SIAMS Photolab). В работе был измерен средний размер частиц керамик оксида алюминия допиированных металлами и построено распределение по размерам.

This thesis addresses simulation of electrochemical experiments, with an emphasis on processes of diffusional mass transport to electrode surface. Following system has been studied: &bull; Applying theoretical modeling and experimentation is shown that even significant surface roughness produced by deliberate polishing or scratching is not sufficient to be distinguished in cyclic voltammetry experiments conducted under the usual conditions. In stripping voltammetry experiment the shape of the voltammograms strongly depends on the model of the electron transfer but is not always sensitive to the precise model of the electrode surface; the conditions under which this is the case are identified, and generic roughness effects on stripping voltammetry are quantified. Electrode roughness can have a significant effect on the stripping of the metals from the solid electrode especially in respect of the voltammetric waveshape. &bull; We first consider two different models of electrodes covered with electroinactive layers: the electrode is covered with a uniform layer and the layer contains pinholes. Both models are simulated and then compared to identify conditions under which they can be distinguished. Next we propose generic model to predict the influence of electroactive layer on the cyclic voltammetric. The conditions under which deviation from the behavior of a planar electrode are predicted. &bull; We first consider one electron, one proton and next two electron, two proton reduction of surface bound species. Two mechanisms of reaction are considered: stepwise and concerted. Voltammetry studied under the three regimes of protons mass transport: infinitely fast (fully buffered solution), infinitely slow (infinitely high surface coverage of electrode) and intermediate case of finite rate of diffusional mass transport to electrode surface. Types of voltammograms observed in each case are presented and discussed. &bull; Theory of chronoamperometry on disc and ring-recessed microelectrodes and their arrays is reported. Three and four different regimes of transient current versus time can be observed at microelectrode arrays of disc and ring electrodes, accordingly. A generic, accurate and easy to use method of experimental chronoamperometric data analysis is proposed. It is shown that the method can be applied to the simultaneous measurement of D and nC in solution. &bull; The fabrication, characterization, and use of arrays of ring-recessed disk generator-colector microelectrodes are reported. Experiments and simulations relating to time- of-flight experiments in which material electrogenerated at a disk is diffusionally transported to the ring are reported. We further study voltammetry of electrochemically active species which undergoes first and second order chemical reactions. Current transients are found to be sensitive to the diffusion coefficient of both the reduced and oxidised species as well as to the rate of the chemical reaction and its mechanism.

Metal oxides are of immense technological importance. Their wide variety of structural and electronic characteristics leads to a flexibility unrivalled by other groups of materials. However, there is still much debate about the fundamental properties of some of the most widely used oxides, including TiO₂ and In₂O₃. This work presents high quality, in-depth characterisation of these two oxides in pure and doped form, including soft and hard X-ray photoelectron spectroscopy and X-ray diffraction. Bulk samples as well as thin film samples were prepared analysed. For the preparation of thin films a high quality sol-gel dip-coating method was developed, which resulted in epitaxial films. In more detail the organisation of the thesis is as follows: Chapter 1 provides an introduction to key ideas related to metal oxides and presents the metal oxides investigated in this thesis, In₂O₃, Ga₂O₃, Tl₂O₃, TiO₂, and SnO₂. Chapter 2 presents background information and Chapter 3 gives the practical details of the experimental techniques employed. Chapters 4 presents reciprocal space maps of MBE-grown In₂O₃ thin films and nanorods on YSZ substrates. Chapters 5 and 6 investigate the doping of In₂O₃ bulk samples with gallium and thallium and introduce a range of solid state characterisation techniques. Chapter 7 describes the development of a dip-coating sol-gel method for the growth of thin films of TiO₂ and shows 3D reciprocal space maps of the resulting films. Chapter 8 concerns hard x-ray photoelectron spectroscopy of undoped and Sn-doped TiO₂. Chapter 9 interconnects previous chapters by presenting 2D reciprocal space maps of nano structured epitaxial samples of In₂O₃ grown by the newly developed sol-gel based method. Chapter 10 concludes this thesis with a summary of the results.