Ce travail de thèse porte sur l'analyse de nanofils de ZnO dopés au cobalt par implantation ionique, en utilisant la fluorescence des rayons X, la spectroscopie d'absorption des rayons X et les techniques de diffraction des rayons X à l'échelle nanométrique sur la ligne de lumière ID22 de l'Installation Européenne de Rayonnement Synchrotron. Les nanofils sont obtenus par croissance catalysée sur des substrats de p-Si (100). Les nanofils de ZnO synthétisés ont été dopés avec du cobalt par d'implantation ionique. Pour la première fois, l'utilisation combinée des techniques de caractérisation par rayons X citées ci-dessus nous permet d'étudier l'homogénéité de la distribution des dopants, la composition, ainsi que l'ordre structurel à courte et grande distance de nanofils individuels. Les résultats de la nano-fluorescence des rayons X indiquent que le dopage au cobalt par implantation ionique dans les nanofils de ZnO est homogène, avec les concentrations désirées. La spectroscopie d'absorption de rayons X et l'analyse des données de diffraction de rayons X fournissent de nouvelles informations sur la distorsion du réseau cristallin produite par l'introduction de défauts structuraux par le processus d'implantation ionique. Ces résultats soulignent l'importance du recuit thermique après l'implantation pour récupérer la structure des nanofils de ZnO à l'échelle du nanomètre. Les mesures complémentaires de micro-photoluminescence et cathodo-luminescence corroborent ces résultats. En conclusion, les méthodes utilisées dans cette thèse ouvrent de nouvelles voies pour l'application de mesures multi-techniques basées sur le rayonnement synchrotron pour l'étude détaillée des nanofils semi-conducteurs à l'échelle nanométrique. / The PhD dissertation focuses on the investigation of single Co-implanted ZnO nanowires using X-ray fluorescence, X-ray absorption spectroscopy, and X-ray diffraction techniques with nanometer resolution at the beamline ID22 of the European Synchrotron Radiation Facility. The ZnO nanowires were grown on p-Si (100) substrates using vapor-liquid-solid mechanism. The synthesized ZnO nanowires were doped with Co via an ion implantation process. For the first time, the combined use of these techniques allows us to study the dopant homogeneity, composition, short- and large-range structural order of individual nanowires. The nano-X-ray fluorescence results indicate the successful and homogeneous Co doping with the desired concentrations in the ZnO nanowires by an ion implantation process. The nano-X-ray absorption spectroscopy and X-ray diffraction data analyses provide new insights into the lattice distortions produced by the structural defect formation generated by the ion implantation process. These findings highlight the importance of the post-implantation thermal annealing to recover the structure of single ZnO nanowires at the nanometer length scale. Complementary microphotoluminescence and cathodoluminescence measurements corroborrate these results. In general, the methodologies used in this work open new avenues for the application of synchrotron based multi-techniques for detailed study of single semiconductor nanowires at the nanoscale.

Para melhorar a visualização das pequenas estruturas anatômicas importantes para o diagnóstico do câncer de mama e otimizar o processamento das mamografias pelos sistemas computadorizados de auxílio ao diagnóstico (CAD), foi desenvolvido um dispositivo, baseado na tecnologia slit, que melhora a aquisição dos mamogramas. Este dispositivo reduz a radiação espalhada e o tamanho do foco e foi projetado a partir de um modelo computacional. O modelo adotado permite quantificar o valor desses parâmetros para qualquer sistema radiológico, qualquer espessura de tecidos moles radiografada e qualquer tensão aplicada ao tubo de raios-X. O dispositivo foi implementado e testado, quantificando as melhorias obtidas. As imagens geradas foram comparadas com as fornecidas pelos sistemas mamográficos convencionais. O modelo serviu para estudar também a interferência do espalhamento sobre o desempenho dos algoritmos usados nos sistemas de diagnóstico auxiliado por computador (CAD). / In order to improve the visualization of the small and important anatomical structures for breast cancer diagnosis and to optimize the image processing of mammograms by the computer aided diagnosis systems (CAD), a device that comes from slit technology was developed to improve the acquisition of mammograms. This device reduces the amount of scattered radiation and the focus size and it can be projected from a computational model. This model allows quantifying the value of those parameters, scattered radiation and the focus size, for any radiological system, any X-rayed soft tissue thickness and any tension applied to the X-ray tube. The device was implemented and tested quantifying the obtained improvements. The generated images were compared to the supplied for conventional mammography systems. The model was also good for studying interference on the algorithms used in the computer aided diagnosis systems (CAD).

Atualmente, no Brasil e exterior, as avaliações de peças industriais nos sistemas radiográficos são feitas durante ou após a fabricação de maneira a verificar a integridade interna das mesmas. Esses ensaios são de suma importância para atender os requisitos de normas, de projetos e de utilização, garantindo a qualidade e confiabilidade, reduzindo os riscos de quebra de equipamentos e para vidas humanas. Os ensaios radiográficos e fluoroscópicos industriais são métodos de ensaios não destrutivos que se baseiam na absorção diferenciada da radiação penetrante pela peça que está sendo ensaiada. Essa variação na quantidade de radiação absorvida é detectada através de um meio que irá nos indicar, entre outras coisas, a existência de uma descontinuidade interna. Este trabalho tem por objetivo fornecer uma base de dados concreta, baseada em experimentos práticos e reais, que gere conhecimento de suporte ao responsável pela instalação radioativa neste momento decisório através da comparação das diversas técnicas no ensaio de peças de ferro fundido nodular. Os ensaios de campo foram executados com equipamentos de raios X de energia máxima de 320 kV com potencial constante, em 15 peças de ferro fundido nodular, utilizando 05 técnicas de captação de imagem, que são: radiografia convencional, radiografia computadorizada, radiografia digital, fluoroscopia analógica e fluoroscopia digital. As radiografias resultantes dos diversos tipos de captação de imagem foram laudadas por inspetores qualificados pela norma de qualificação de pessoal na área aeronáutica (NAS 410, 2008), e os resultados dos ensaios, para verificar a melhor aderência de cada sistema de imagem com a Norma Nuclear CNEN-NE-3.01, onde qualquer atividade envolvendo radiação deve ser justificada em relação a outras alternativas e produzir um benefício líquido positivo. O nível da aceitabilidade das descontinuidades para que o inspetor possa laudar as radiografias é um acordo entre cliente e fornecedor e, neste caso, foi determinado o nível de qualidade de imagem de 2:4T um nível adequado de qualidade, 2:2T um nível bom e 2:1T um nível ótimo de qualidade de imagem. / Now a days, in Brazil and exterior, the evaluations of industrial parts through X-rays systems are made during or after producing verifying the internal integrity of them. Those testing are sum important for the norms requirements, of projects and utilization, guaranteeing the quality and reliability, reducing the equipment break risks and for human lives. The radiográficos and fluoroscópicos industrial testing are methods of non destructive testing that is based on the differentiated absorption of penetrating radiation by the part that is being tested. That variation in the radiation quantity absorbed is detected through an indicate environment, between other things, the existence of an internal descontinuidade. This paper has for objective supply a base of concrete facts, based in real and practical experiments, that manages knowledge of support to the responsible for the radioactive installation in this decisive moment through the comparison of diverse techniques tested in nodular cast iron parts. The field practice were performed with equipment of X-rays 320 kV maximum energy with constant potential, in 15 pieces nodular cast iron, utilizing 05 image collection techniques, that are: conventional x-ray, x-ray computerized, digital x-ray, fluoroscopia analog and fluoroscopia digital. The resultant x-rays of the diverse image collection kinds were attested by inspectors qualified by t personals qualification norm in the aeronautic area (IN THE 410, 2008), and the results of the testing, verify the better adhesion of each system of image to the Nuclear Norm CNEN-NE-3.01, where any activity involving radiation should be justified regarding other alternatives and produce a positive liquid benefit. The level of the acceptability of the descontinuidades for that the inspector be able to laudar the x-rays is an agreement between client and supplying and, in that case, was determined the image quality level of 2:4T, an adequate level of quality is 2:2T and great level of quality of 2:1T.

No description available.

Investigating and mapping fundamental processes in nature is a driving force for breakthroughs in research and technology. Doing so, requires knowledge of the smallest scales of the world. One way of performing measurements on these scales is through intense x-ray sources, which have improved greatly over the last decades. By combing these sources with state of the art optics, even higher flux densities can be reached, allowing for faster measurements and ground-breaking discoveries.  This study aims to explore the performance of polycapillary optics, when aligned to one of the most intense x-ray micro sources in the world, the liquid-metal-jet D2+. Knife edge scans were performed together with a photon-counting medipix x-ray camera to quantify focus properties such as, flux, flux density, transmission, gain and beam width. Measurements were conducted with a 20 μm source spot that was compared to a simulated 200 μm source spot, both at 260 W electron beam power. The data from vertical and horizontal scans were combined to reconstruct the 2D functionality of the polycapillary optic. The flux density were almost four times higher with the 20 μm spot compared to the simulated 200 μm spot. This result correlated with the condition for total external reflection and the local divergence. The conclusion is that the small source spot of the liquid-metal-jet source improves the efficiency of the polycapillary optic.  The efficiency could still be improved, if the deviation in the pointing accuracy could be minimized. Furthermore, the combination of liquid-metal-jet x-ray source and the polycapillary optic, achieved extremely high flux densities. This was specially compared to an x-ray source used for confocal micro XRF, where the flux was almost nine times higher with the liquid-metal-jet x-ray source. This allows for faster measurements within confocal micro XRF and other techniques demanding very high flux densities, but with low demands on beam divergence and spectral purity.

Transition-metal oxides (TMOs) display numerous fascinating and complex properties, such as mixed-valency, low dimensionality, lattice distortion, and phase transition, etc. These properties arise from the partially filled d- or f-electron shells of TM cations and are often accompanied by the intriguing interplay between degrees of freedom. To understand the complexity of d-electron TMOs, this thesis is primarily focused on studying their underlying electronic structure using X-ray absorption spectroscopy (XAS), X-ray emission spectroscopy (XES), X-ray photoemission spectroscopy (XPS), and resonant inelastic X-ray scattering (RIXS). The measurements at the O K- and TM L-edges are achieved by taking advantage of high-flux and high-resolution synchrotron radiation light with tunable monochromatic photon energy. Four electronically and structurally distinctive oxides are selected as representative TMOs for investigation in this thesis. To begin with, through a comparative study of WO3 and Na0.67WO3 crystals, the narrowing of the conduction band is observed with Na doping and the core-hole energy shift in the O K-edge XAS process is experimentally determined. Indirect and direct band gaps of photoanode WO3 are measured from the resonant XES with polarization-dependent experimental geometry. The other sodium bronze studied is quasi-one-dimensional β-Na0.33V2O5 polycrystalline film. The film stoichiometry, preferential orientation, and orbital anisotropy are well characterized by a variety of photon and electron techniques and compared to density-functional theory (DFT) calculation. The V 3d orbital splitting of β-Na0.33V2O5 is surveyed by the V L-edge RIXS and compared with isoelectronic β-Sr0.17V2O5 regarding distortions to VO6 octahedra. Furthermore, the complex electronic structure of Mott insulators La1-xLuxVO3 is investigated to understand their spin-orbital phase diagram. The effects of rare-earth size on the O 2p hybridization states and the local crystal field of VO6 octahedron are found to agree with the prediction of DFT calculation and the evolution of crystal structure. The changes of experimental spectra with temperature are associated with Jahn-Teller distortion and orbital ordering due to structural phase transition. Lastly, the band structure and low-energy excitations of spinel MnV2O4 are explored using soft x-ray spectroscopies and theoretical calculations. The presence of Hubbard bands and the mixing between V and Mn 3d states are suggested both experimentally and theoretically.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第18591号 / 工博第3952号 / 新制||工||1607(附属図書館) / 31491 / 京都大学大学院工学研究科材料工学専攻 / (主査)教授 河合 潤, 教授 酒井 明, 教授 伊藤 秋男 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

No description available.

This thesis presents a study on two types of X-ray diffraction methodologies applied to the characterization of amorphous materials. The purpose of this study was to assess the feasibility of measuring the diffractive spectrum of amorphous materials by Energy-Dispersive X-ray Diffraction (EDXRD) utilizing Cadmium Zinc Telluride detectors. The total scattering intensity (coherent plus incoherent scatter) spectra precisely measured by high-energy Wide-Angle X-ray Scattering (WAXS) were compared to the EDXRD spectra to determine the level of agreement between the two techniques. The EDXRD spectra were constructed by applying a spectra fusing technique which combined the EDXRD spectra collected at different scattering angles rendering a continuous total scattering spectrum. The spectra fusing technique extended the momentum transfer range of the observed scattered spectrum beyond the limitations of the X-ray source and CZT detection efficiencies. Agreement between the WAXS and fused EDXRD spectra was achieved. In addition, this thesis presents the atomic pair correlation functions and coordination numbers of the first coordination shell for four hydrogen peroxide solutions of varying mass concentrations using Empirical Potential Structural Refinement (EPSR). The results are compared to the state-of-the art ad initio quantum mechanical charge field molecular dynamics (QMCF MD) model of the hydrogen peroxide in solution to support the model's predictions on why hydrogen peroxide is stable in water. The EPSR results using the coherent scattering intensity calculated from the WAXS data set predicts a hydration shell of 6.4 molecules of water surrounding hydrogen peroxide. The results also indicate that hydrogen peroxide is more likely to behave as a proton donor than acceptor. These findings are in agreement with QMCF MD model of aqueous hydrogen peroxide. / Physics

This dissertation presents a discussion of blocky and randomly functionalized sulfonated syndiotactic polystyrene copolymers. These copolymers have been prepared over a range of functionalization (from 2% to 10%) in order to assess the effect of the incorporation of these polar side groups on both the thermal behavior and morphology of these polymer systems. The two different architectures are achieved by conducting the reaction in both the heterogeneous gel-state to obtain blocky copolymers and in the homogeneous solution state to obtain randomly functionalized copolymers. In order to compare both the thermal properties and morphology of these two systems several sets of samples were prepared at comparable levels of sulfonation. Thermal analysis of these two systems proved that the blocky functionalized copolymers provided superior properties with regard to the speed and total amount of the crystalline component of sulfonated syndiotactic polystyrene. Above 3% functionalizion the randomly functionalized copolymer was no longer able to crystallize, whereas, the blocky functionalized copolymer is able to crystallize even at a functionalization level of 10.5% sulfonate groups. When considering the morphology of these systems even at low percentages of sulfonation it is clear that the distribution of these groups is different based on the amplitude of the signal measured by small angle x-ray scattering. Additionally, methods were developed to describe both the distribution of ionic multiplets, which varies between blocky and randomly functionalized systems, but also the distribution of crystals. At a larger scale ultra-small angle x-ray scattering was employed to attempt to understand the clustering of ionic multiplets in these systems. Randomly functionalized polymers should a peak that is attributed to ion clusters, whereas blocky polymers show no such peak. Additional studies have also been done to look at the analysis of crystallite sizes in these systems when there are multiplet polymorphs present, it was observed the polymorphic composition is drastically different. All of these studies support that these systems bear vastly different thermal behavior and possess significantly different morphologies. This supports the hypothesis that this gel-state heterogeneous functionalization procedure produces a much different chain architecture compared to homogeneous functionalization in the solution-state. / Doctor of Philosophy / Polymers are a class of chemicals that are defined by having a very large set of molecules that are chemically linked together where each unit (monomer) is repeated within the chemical structure. In particular, this dissertation focuses on the construction what are termed as "blocky" copolymers, which are defined by having two chemically different monomers that are incorporated in the polymer chain. The "blocky" characteristic of these polymers means that these two different monomers are physically segregated from each other on the polymer chain, where long portions of the chain that are of one type, followed by another section of the polymer that has the other type of monomer. The goal of creating this type of structure is to try to take advantage of the properties of both types of monomers, which can create materials with superior synergistic properties. In this case a hydrophobic (water hating) monomer is combined with a hydrophilic (water loving) chain. This hydrophobic component in the polymer is able to crystallize, which provides mechanical and thermal stability in the material by acting as a physical tether to hold neighboring chains together. With the other set of hydrophilic monomers, which in this case have an ionic component incorporated, we can now take advantage of this chemical components ability to aide in the transportation of ions. Transportation of ions is useful in a variety of commercially relevant applications, two of the most important applications of these ionic materials is in membranes that can be used to purify water or membrane materials in fuel cell technologies, specifically for proton exchange membranes. The focus of this research in particular was to create a simple synthesis technique that can create these blocky polymer chain architectures, which is done by performing the reaction while the polymer is made into a gel. The key to this is that the crystals within the gel act as a barrier to chemical reactions, creating conditions where we have substantial portions of the material that are able to be functionalized and the crystals within the material that are protected from being functionalized. By looking at the thermal characteristics, such as melting temperatures and amount of crystals within these systems we have seen that functionalizing these polymers in the heterogeneous gel state gives substantially better properties than functionalizing these materials randomly. Much like oil and water, incompatible polymer chains will phase separate from each other. In this case the hydrophobic and ionic components will phase separate from each other. The shape and distribution of these phase separated structure will dictate many of the material properties, which can be described by modeling the data collected from x-ray scattering experiments. All of this information will tell us based on the initial conditions that these polymers were created in, what properties should be expected based on the morphology and thermal behavior. This gives a better understanding of how to fine tune these properties based on the structure of the gel and chemical reaction conditions.