• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 1
  • 1
  • Tagged with
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Application des faisceaux d'ions focalisés à la création de centres NV du diamant. Caractérisation de ces faisceaux d'ions issus d'une source plasma. / Application of focused ion beams to the creation of NV centers in diamond. Characterization of these ion beams from a plasma source.

Renaud, Justine 24 June 2019 (has links)
Depuis plus de 45 ans, les colonnes à faisceaux d'ions focalisés FIB à base de source à métal liquide (Ga) sont utilisées pour l'élaboration, la modification ou l'analyse de nanostructures. Beaucoup plus récemment, moins de 10 ans, les sources plasma sont intégrées dans les FIB afin de répondre aux besoins d'analyse de défaillance mais également de préparation d'échantillons. Ce marché des FIB plasma est en forte progression ces derniers années et s'accompagne d'une amélioration permanente des spécifications de cette technologie encore jeune. Il est donc nécessaire de caractériser au mieux ces sources afin de pouvoir améliorer l'optique associée. Dans cette thèse, nous présentons le développement d'une nouvelle colonne FIB fonctionnant avec une source d'ions plasma, dédiée à la création de centres NV, ainsi que le développement d'un outil permettant de caractériser les performances de cette source.Étant donné le contexte de ces travaux, la première partie du manuscrit est consacrée à la présentation de la technologie FIB, de son fonctionnement et de ses applications. Dans le second chapitre, nous présentons le développement d'une colonne FIB dédiée à l'implantation d'ions azote pour la création contrôlée de centres colorés NV dans des diamants. Nous commençons par introduire les propriétés uniques des centres NV ainsi que les méthodes usuelles pour leur création. Nous présentons ensuite les différentes étapes de la caractérisation de cette colonne FIB. Les implantations réalisées au cours de ce travail ont pu être utilisées pour le développement d'une nouvelle application des diamants dopés.Dans le dernier chapitre du manuscrit, nous nous intéressons à la conception d'un banc de test permettant d'obtenir les paramètres clés de la source d'ions, à savoir la dispersion en énergie et l'émittance. Les méthodes usuelles de mesure de ces paramètres sont présentées puis le fonctionnement du banc de test est entièrement décrit. Nous présentons ensuite les mesures effectuées avec des faisceaux d'ions xénon puis oxygène. Certains paramètres de la source d'ions plasma ont ainsi été obtenus. / For more than 45 years, focused ion beams FIB columns based on liquid metal ion sources (Ga) have been used for the development, modification or analysis of nanostructures. Much more recently, less than 10 years ago, plasma sources are integrated in FIBs to meet the needs of failure analysis as well as sample preparation. This plasma FIB market has grown strongly in recent years and is accompanied by a permanent improvement of the specifications of this young technology. Therefore, it is necessary to characterize these sources in order to improve the associated optics. In this thesis, we present the development of a new FIB column working with a plasma ion source, dedicated to the creation of NV centers, as well as the development of a system dedicated to the characterization of the performances of this source.Given the context of this work, the first part of the manuscript is dedicated to the presentation of FIB technology, its operation and its applications. In the second chapter, we present the development of a FIB column dedicated to the implantation of nitrogen ions for the controlled creation of NV color centers in diamonds. We begin by introducing the unique properties of NV centers as well as the usual methods for their creation. Then we present the different steps of the characterization of this FIB column. The implantations carried out during this work have been used for the development of a new application of doped diamonds.In the last chapter of the thesis, we are interested in designing a test bench to obtain the key parameters of the ion source, namely energy dispersion and emittance. The usual methods for measuring these parameters are presented and the operation of the test bench is fully described. Then we then present the measurements made with beams of xenon ions and oxygen ions. Some parameters of the plasma ion source have thus been obtained.
2

Estudo teórico da forma de linha de absorção do poli(p-fenileno vinileno)

Silva, Marcelo Castanheira da 05 November 2013 (has links)
Fundação de Amparo a Pesquisa do Estado de Minas Gerais / In this work we made a theoretical study of absorption line-shape of poly (pphenylene vinylene) (PPV). The model was applied in films processed by techniques: spin-coating (SC), layer-by-layer (LbL), and Langmuir-Blodgett (LB). The probability of electronic transitions was calculated based on the molecular model of excitons, Franck-Condon states, Gaussian distribution of non-entangled chains with conjugate degree n, semi-empirical parameterization of energy gap, electric dipole moment, and electron-vibrational mode coupling. Based on the approach of the energy gap functional dependence 1/n, the inclusion of the non-homogeneity energy dispersion 1/n2 is essential to obtain good experimental data agreement, mainly, where the absorption spectra display peaks width of about 65 meV. For unresolved absorption spectra, such as those observed for a large number of conjugated polymers processed via spin-coating technique, for example, the non-homogeneity energy dispersion parameterization is not significant. We develop a model to describe the possible chemical reactions of conversion of poly(xylyliden tetrahydrothiophenium chloride) (PTHT) monomers to PPV monomers and PPV monomers in others monomers of different degrees of conjugation. The dependence 1/n of the functional energy gap was compared with experimental data oligomers and calculations optimized geometry by Density Functional Theory (DFT). Effects of exciton confinement were considered in the transition dipole moment functional. Simulations to calculate the oscillator strength of the absorption spectra in PPV oligomers indicate that the HOMO-LUMO state prevails over other excited states. Results obtained from the use of the distribution of the random walk are as good as those achieved by the use of Gaussian distribution of conjugated segments in simulations of absorption spectra of the PPV. The use of transition dipole moment functional, which includes the effect of exciton confinement together with the distribution of the random walk provide good results in adjustments theoretical absorption spectra of PPV with more consistent physical parameters. / Nesse trabalho fizemos um estudo teórico da forma de linha de absorção do poli(p-fenileno vinileno) (PPV). O modelo foi aplicado em filmes processados pelas técnicas: spin-coating (SC), layer-by-layer (LbL) e Langmuir-Blodgett (LB). A probabilidade de transição eletrônica foi calculada com base no modelo do exciton molecular, estados de Franck-Condon, distribuição Gaussiana de cadeias não emaranhadas com grau de conjugação n, parametrização semi-empírica do gap de energia, do momento de dipolo elétrico e do acoplamento eletrônico vibracional. Baseamos na aproximação do funcional do gap de energia de dependência 1/n, a inclusão da dispersão de energia não homogênea 1/n2, que é essencial para se obter uma boa concordância com os dados experimentais, principalmente em casos, onde o espectro de absorção apresenta picos com largura de aproximadamente 65 meV. Em espectros de filmes pouco definidos, tais como os processados pela técnica spin-coating, a dispersão de energia não homogênea não é significativa. Desenvolvemos um modelo para descrever as possíveis reações químicas de conversão de monômeros de poli- (cloreto de xilideno tetrahidrotiofeno) (PTHT) em PPV e de monômeros de PPV em outros de diferentes graus de conjugação. A dependência 1/n do funcional do gap de energia foi comparada com dados experimentais de oligômeros de PPV e cálculos otimizados da geometria pela Teoria do Funcional da Densidade (DFT). Efeitos de confinamento de exciton foram considerados no funcional do momento de dipolo de transição eletrônica. Simulações feitas para calcular a força de oscilador no espectro de absorção em oligômeros de PPV indicam que o estado HOMO-LUMO prevalece sobre outros estados excitados. Resultados obtidos pelo uso da distribuição do passeio aleatório são tão bons quanto aos realizados pelo uso da distribuição Gaussiana de segmentos conjugados em simulações de espectros de absorção do PPV. O uso do funcional do momento de dipolo de transição, que inclui efeito de confinamento de excitons, junto com a distribuição do passeio aleatório propiciam bons resultados nos ajustes teóricos de espectros de absorção do PPV com parâmetros físicos mais consistentes. / Doutor em Física

Page generated in 0.0592 seconds