Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro / Este trabalho teve por objetivo a realização do estudo das propriedades ópticas, magnéticas e estruturais do cristal elpasolita Cs2NaAlF6 dopado com as concentrações de 0,1%, 1,0%, 3,0%, 10,0%, 30,0% e 50,0% de Cr3+. O interesse no estudo deste sistema reside na existência de uma larga e intensa banda de luminescência na temperatura ambiente, que se estende do visível ao infravermelho próximo, podendo então ser utilizado como fonte de radiação sintonizável em dispositivos ópticos, optoeletrônicos e detectores, entre outros. Para a investigação das propriedades ópticas foram feitas medidas de luminescência, excitação e luminescência resolvida no tempo, na temperatura ambiente e a baixas temperaturas. Os resultados obtidos mostram largas bandas de luminescência atribuídas aos íons de Cr3+, ocupando dois sítios octaédricos não equivalentes. Os resultados também mostram que a intensidade integrada da luminescência, o baricentro da banda de emissão e o tempo de vida do estado luminescente variam com a concentração de impureza residente no sistema. Foram realizadas medidas de calor específico em função do campo magnético em uma larga faixa de temperatura, cujos resultados mostram o aparecimento do efeito Schottky a baixas temperaturas. Medidas de susceptibilidade magnética em funcão da temperatura também foram realizadas, e mostram um comportamento paramagnético, típico do íon impureza Cr3+, com um ordenamento magnético de curto alcance. Para a determinação das propriedades estruturais foram realizadas medidas de difração de nêutrons na temperatura ambiente. / This work is devoted to study the optical, magnetic and structural properties of the elpasolite crystal Cs2NaAlF6 with 0.1, 1.0, 3.0, 10.0, 30.0 and 50.0% of Cr3+ ions. The interest on this material lies on the fact that such system presents a broad, intense band in the visible and infrared regions at room temperature and therefore can be used as a tunable radiation source in optical, optoelectronic devices and detectors, among others. To investigate the optical properties luminescence, excitation and time-resolved luminescence measurements at room and low temperatures were realized. The results show broad bands attributed to the Cr3+ ions in two non-equivalent sites, both of them with octahedral coordination. The results also show that the luminescence integrated intensity, emission baricenter and luminescence lifetime change with the change of impurity doping. Specific heat measurements were performed as a function of magnetic field in a wide temperature range, whose results show the appearance of the Schottky effect at very low temperatures. The magnetic susceptibility measurements show a paramagnetic behavior, typical of the dopant ion Cr3+, with a short-range magnetic ordering. To determine the structural properties, neutron diffraction measurements were realized at room temperature.

Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro / Este trabalho teve por objetivo a realização do estudo das propriedades ópticas, magnéticas e estruturais do cristal elpasolita Cs2NaAlF6 dopado com as concentrações de 0,1%, 1,0%, 3,0%, 10,0%, 30,0% e 50,0% de Cr3+. O interesse no estudo deste sistema reside na existência de uma larga e intensa banda de luminescência na temperatura ambiente, que se estende do visível ao infravermelho próximo, podendo então ser utilizado como fonte de radiação sintonizável em dispositivos ópticos, optoeletrônicos e detectores, entre outros. Para a investigação das propriedades ópticas foram feitas medidas de luminescência, excitação e luminescência resolvida no tempo, na temperatura ambiente e a baixas temperaturas. Os resultados obtidos mostram largas bandas de luminescência atribuídas aos íons de Cr3+, ocupando dois sítios octaédricos não equivalentes. Os resultados também mostram que a intensidade integrada da luminescência, o baricentro da banda de emissão e o tempo de vida do estado luminescente variam com a concentração de impureza residente no sistema. Foram realizadas medidas de calor específico em função do campo magnético em uma larga faixa de temperatura, cujos resultados mostram o aparecimento do efeito Schottky a baixas temperaturas. Medidas de susceptibilidade magnética em funcão da temperatura também foram realizadas, e mostram um comportamento paramagnético, típico do íon impureza Cr3+, com um ordenamento magnético de curto alcance. Para a determinação das propriedades estruturais foram realizadas medidas de difração de nêutrons na temperatura ambiente. / This work is devoted to study the optical, magnetic and structural properties of the elpasolite crystal Cs2NaAlF6 with 0.1, 1.0, 3.0, 10.0, 30.0 and 50.0% of Cr3+ ions. The interest on this material lies on the fact that such system presents a broad, intense band in the visible and infrared regions at room temperature and therefore can be used as a tunable radiation source in optical, optoelectronic devices and detectors, among others. To investigate the optical properties luminescence, excitation and time-resolved luminescence measurements at room and low temperatures were realized. The results show broad bands attributed to the Cr3+ ions in two non-equivalent sites, both of them with octahedral coordination. The results also show that the luminescence integrated intensity, emission baricenter and luminescence lifetime change with the change of impurity doping. Specific heat measurements were performed as a function of magnetic field in a wide temperature range, whose results show the appearance of the Schottky effect at very low temperatures. The magnetic susceptibility measurements show a paramagnetic behavior, typical of the dopant ion Cr3+, with a short-range magnetic ordering. To determine the structural properties, neutron diffraction measurements were realized at room temperature.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Esta tese apresenta as espectroscopias de fotoluminescência, excitação e fotoacústica de amostras MgGa2O4 dopadas com 0,1%, 0,5% e 1,0% de Ni2+, obtidas pelo método de estado sólido e duas amostras distintas GaNbO4-GaNb11O29-Ga2O3 dopadas com 1,0% de Cr3+, uma sintetizada por reação de estado sólido e a outra pelo método de acetato. As amostras foram identificadas por Difração de Raios X e os dados foram refinados pelo método de Rietveld. A morfologia das amostras foi observada por Microscopia Eletrônica de Varredura. Os espectros ópticos das amostras apresentaram bandas de absorção e emissão do visível ao infravermelho próximo. As transições de energia foram analisadas com base na teoria de campo cristalino e os parâmetros de energia foram obtidos a partir de espectros de absorção e das matrizes de Tanabe-Sugano. / This work presents the photoluminescence, excitation and photoacoustic spectroscopy of samples MgGa2O4 doped with 0.1%, 0.5% and 1.0% of Ni2+, obtained through solid state method and two different samples GaNbO4-GaNb11O29-Ga2O3 doped with 1.0% of Cr3+, one synthesized by solid state reaction and another by wet chemical method. The samples were identified by X Ray Diffraction and the data were refined by Rietveld method. The morphology of samples was observed by SEM. The optical spectra of samples showed emission and absorption bands from visible to near infrared. The energy transitions were analyzed based on the crystal field theory and the energy parameters were obtained from absorption spectra and Tanabe-Sugano matrices.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Esta tese apresenta as espectroscopias de fotoluminescência, excitação e fotoacústica de amostras MgGa2O4 dopadas com 0,1%, 0,5% e 1,0% de Ni2+, obtidas pelo método de estado sólido e duas amostras distintas GaNbO4-GaNb11O29-Ga2O3 dopadas com 1,0% de Cr3+, uma sintetizada por reação de estado sólido e a outra pelo método de acetato. As amostras foram identificadas por Difração de Raios X e os dados foram refinados pelo método de Rietveld. A morfologia das amostras foi observada por Microscopia Eletrônica de Varredura. Os espectros ópticos das amostras apresentaram bandas de absorção e emissão do visível ao infravermelho próximo. As transições de energia foram analisadas com base na teoria de campo cristalino e os parâmetros de energia foram obtidos a partir de espectros de absorção e das matrizes de Tanabe-Sugano. / This work presents the photoluminescence, excitation and photoacoustic spectroscopy of samples MgGa2O4 doped with 0.1%, 0.5% and 1.0% of Ni2+, obtained through solid state method and two different samples GaNbO4-GaNb11O29-Ga2O3 doped with 1.0% of Cr3+, one synthesized by solid state reaction and another by wet chemical method. The samples were identified by X Ray Diffraction and the data were refined by Rietveld method. The morphology of samples was observed by SEM. The optical spectra of samples showed emission and absorption bands from visible to near infrared. The energy transitions were analyzed based on the crystal field theory and the energy parameters were obtained from absorption spectra and Tanabe-Sugano matrices.

The macrophage receptors that mediate phagocytosis of Borrelia burgdorferi, the Lyme disease spirochete, are unknown despite this cell type's importance in promoting pathogen clearance and inflammation-mediated tissue damage. We now demonstrate that the β2 integrin, Complement Receptor 3 (CR3), mediates the phagocytosis of opsonized and non-opsonized spirochetes by murine macrophages and human monocytes. Although, expression of the surface proteins, CspA and OspE, protects B. burgdorferi from complement-mediated phagocytosis, the versatility of CR3 counteracts the ability of B. burgdorferi to interfere with complement activation and complement-derived opsonins, thus minimizing the bacteria's anti-complement strategy. Interaction of the spirochete with the integrin is not sufficient to internalize B. burgdorferi; however, phagocytosis occurs when the GPI-anchored protein, CD14, is coexpressed in CHO-CR3 cells. CR3-mediated phagocytosis occurs independently of MyD88-induced or inside-out signals but requires the translocation of the integrin to cholesterol rich membrane microdomains. Interestingly, the absence of CR3 leads to marked increases in production of TNF in vitro and in vivo, in spite of reduced spirochetal uptake. Overall, our data establish CR3 as a MyD88-independent phagocytic receptor for B. burgdorferi that also participates in the modulation of the proinflammatory output of macrophages. Macrophages are critical cellular components of the immune response to infectious agents. During infection with B. burgdorferi, macrophages infiltrate the cardiac tissue and induce the activation of invariant NKT cells, leading to the production of the protective cytokine IFNγ. The interaction of macrophages with infectious agents leads to the activation of several signaling cascades, including mitogen activated protein kinases, such as p38 MAP kinase. We now demonstrate that p38 MAP kinase-mediated responses are critical components to the immune response during infection with B. burgdorferi. The inhibition of p38 MAP kinase does not alter the ability of macrophages to phagocytose B. burgdorferi; however, inhibition of p38 during infection with B. burgdorferi results in increased carditis. Through the generation of transgenic mice that express a dominant negative form of p38 MAP kinase specifically in macrophages, we demonstrate that this kinase regulates the production of the iNKT attracting chemokine, MCP-1 and the infiltration of these cells to the cardiac tissue during infection. Overall, the inhibition of p38 MAP kinase during infection with B. burgdorferi specifically in macrophages results in the deficient infiltration of iNKT cells and their diminished production of IFNγ, leading to increased bacterial burdens and inflammation. These results show that p38 MAP kinase provides critical checkpoints for the protective immune response to the spirochete during infection of the heart.

Filmes amorfos de nitreto de alumínio (AlN) foram preparados por sputtering de rádio frequência convencional em um alvo de Al+Cr e plasma de nitrogênio puro. A área relativa de Al-Cr determina o conteúdo de Cr, o qual esteve em um intervalo de concentração de ~ 0 3.33 at.% no presente estudo. A deposição dos filmes foi seguida por tratamento térmico das amostras até 1050 ºC e por caracterização espectroscópica através de medidas de EDS (Energy Dispersive Spectrometry), Foto-luminescência e Transmissão Óptica. De acordo com os resultados experimentais, as propriedades óptico-eletrônicas dos filmes de AlN contendo Cr são altamente influenciadas tanto pela concentração de Cr como pela temperatura de tratamento térmico. Na verdade, o tratamento térmico a 1050 ºC induz o desenvolvimento de estruturas que, devido ao seu tamanho típico e características espectrais exclusivas, foram designadas por micro-estruturas de rubi (RbMSs). Estas RbMSs são rodeadas por um meio rico em nitrogênio no qual os íons Cr3+ apresentam características luminescentes não encontradas na literatura. A emissão de luz apresentada pelas RbMSs e suas vizinhanças foram investigadas de acordo com o conteúdo de Cr e a temperatura de medida permitindo a identificação de várias linhas luminescentes relatadas do Cr3+. As principais características destas linhas luminescentes e correspondentes processos de recombinação-excitação são apresentados e discutidos tendo em vista uma análise espectroscópica detalhada. / Films of amorphous aluminum-nitride (AlN) were prepared by conventional radio frequency sputtering of an Al+Cr target in a plasma of pure nitrogen. The Cr-to-Al relative area determines the chromium content, which stayed in the ~ 0 3.33 at.% concentration range in the present study. Film deposition was followed by thermal annealing the samples up to 1050 ºC and by spectroscopic characterization through energy dispersive spectrometry (EDS), Photo-luminescence and Optical Transmission measurements. According to the experimental results, the optical-electronic properties of the Cr-containing AlN films are highly influenced by both the Cr concentration and the temperature of the thermal treatments. In fact, thermal annealing at 1050 °C induces the development of structures which, because of their typical size and unique spectral characteristics, were designated by ruby microstructures (RbMS\'s). These RbMS\'s are surrounded by a nitrogen-rich environment in which Cr3+ ions exhibit luminescent features with no counterpart in the literature. The light emission presented by the RbMS\'s and surroundings were investigated according to the Cr content and temperature of measurement allowing the identification of several Cr3+-related luminescent lines. The main characteristics of these luminescent lines and corresponding excitation-recombination processes are presented and discussed in view of a detailed spectroscopic analysis.

Filmes amorfos de nitreto de alumínio (AlN) foram preparados por sputtering de rádio frequência convencional em um alvo de Al+Cr e plasma de nitrogênio puro. A área relativa de Al-Cr determina o conteúdo de Cr, o qual esteve em um intervalo de concentração de ~ 0 3.33 at.% no presente estudo. A deposição dos filmes foi seguida por tratamento térmico das amostras até 1050 ºC e por caracterização espectroscópica através de medidas de EDS (Energy Dispersive Spectrometry), Foto-luminescência e Transmissão Óptica. De acordo com os resultados experimentais, as propriedades óptico-eletrônicas dos filmes de AlN contendo Cr são altamente influenciadas tanto pela concentração de Cr como pela temperatura de tratamento térmico. Na verdade, o tratamento térmico a 1050 ºC induz o desenvolvimento de estruturas que, devido ao seu tamanho típico e características espectrais exclusivas, foram designadas por micro-estruturas de rubi (RbMSs). Estas RbMSs são rodeadas por um meio rico em nitrogênio no qual os íons Cr3+ apresentam características luminescentes não encontradas na literatura. A emissão de luz apresentada pelas RbMSs e suas vizinhanças foram investigadas de acordo com o conteúdo de Cr e a temperatura de medida permitindo a identificação de várias linhas luminescentes relatadas do Cr3+. As principais características destas linhas luminescentes e correspondentes processos de recombinação-excitação são apresentados e discutidos tendo em vista uma análise espectroscópica detalhada. / Films of amorphous aluminum-nitride (AlN) were prepared by conventional radio frequency sputtering of an Al+Cr target in a plasma of pure nitrogen. The Cr-to-Al relative area determines the chromium content, which stayed in the ~ 0 3.33 at.% concentration range in the present study. Film deposition was followed by thermal annealing the samples up to 1050 ºC and by spectroscopic characterization through energy dispersive spectrometry (EDS), Photo-luminescence and Optical Transmission measurements. According to the experimental results, the optical-electronic properties of the Cr-containing AlN films are highly influenced by both the Cr concentration and the temperature of the thermal treatments. In fact, thermal annealing at 1050 °C induces the development of structures which, because of their typical size and unique spectral characteristics, were designated by ruby microstructures (RbMS\'s). These RbMS\'s are surrounded by a nitrogen-rich environment in which Cr3+ ions exhibit luminescent features with no counterpart in the literature. The light emission presented by the RbMS\'s and surroundings were investigated according to the Cr content and temperature of measurement allowing the identification of several Cr3+-related luminescent lines. The main characteristics of these luminescent lines and corresponding excitation-recombination processes are presented and discussed in view of a detailed spectroscopic analysis.

Cette thèse porte sur le développement de fibres optiques de type cœur/gaine, dont le cœur est composé de vitrocéramiques transparentes. Le système étudié est composé d’une matrice de silice stabilisant la phase ZnGa2O4 sous la forme de nano cristaux, pouvant être dopés par des ions de métaux de transition tels que le chrome (III) et le nickel (II). Les verres précurseurs de vitrocéramiques ont été synthétisés par fusion trempe, étirés sous forme de fibres optiques par la méthode poudre puis recuits thermiquement afin d’obtenir des fibres optiques à cœur vitrocéramiques optiquement actives. L’optimisation conjointe de la composition des verres précurseurs, des paramètres de fibrage, de la composition finale des fibres et du protocole de recuit thermique de cristallisation, ont permis de maximiser leurs propriétés de luminescence autour de 700 nm et 1350 nm pour les fibres dopées par du chrome (III) et du nickel (II) respectivement. Ces types de fibres peuvent trouver des applications dans les domaines de la thermométrie optique, des sources optiques, des amplificateurs et des lasers fibrés. En particulier, nous avons démontré que le spectre d’émission autour de 1350 nm des fibres dopées par du nickel (II) présente une largeur à mi-hauteur supérieure à 270 nm, meilleure que celle des sources commerciales centrées autour de 1300 nm. Le niveau de puissance émise, de l’ordre d’une trentaine de microwatts, est quasiment compatible avec les applications de source optique pour l’OCT. Des développements ultérieurs visant à réduire le niveau de pertes dans ces fibres et de maximiser l’efficacité du dopant permettrons d’amener cette technologie à un niveau de performance compatible avec ces applications. Ces résultats encourageants ont motivés le dépôt d’une demande de protection des fibres et de leur procédé d’élaboration par un brevet. / This thesis focuses on the development of core/clad type optical fibers where the core is composed of transparent glass ceramics. The system considered was composed of a silica matrix where ZnGa2O4 nanocrystals can be stabilized. Those crystals can interestingly be doped with transition metal ions such as chromium (III) or nickel (II) ions. The precursor glass were synthetized by melt quenching method, drawn into fibers through the powder in tube process, and subsequently annealed to produce optically active glass ceramic optical fibers. The starting glass composition together with the drawing parameters, the fiber core composition and the annealing protocol were optimized in order to maximize the luminescence properties around 700 nm and 1350 nm in chromium (III) and nickel (II) doped fibers respectively. Such type of fibers are interesting for the domains of optical thermometry, fibered sources, amplifiers and lasers. In particular, we demonstrated that the emission spectrum around 1350 nm of nickel (II) doped glass ceramic fibers exhibited a full width at half maximum above 270 nm, wider than that of 1300 nm centered commercial sources. The overall power outcome is about thirty micro watts, which is almost suitable for OCT applications. Further developments aiming at reducing the optical losses in the fibers and in maximizing the dopant efficiency will allow to reach the applications requirements. Those promising results led to a patent application on the fibers composition and their fabrication process.

No description available.

Cette thèse porte sur l'élaboration de nanoparticules (NPs) à luminescence persistante pour l'imagerie optique dans le domaine du rouge profond et du proche infrarouge. Leur utilisation présente un avantage indéniable, l'étape d'irradiation pour obtenir l'état excité pouvant être réalisée avant injection, il est possible d'éviter tout stress des tissus et autres phénomènes d'autofluorescence. Dans les compositions chimiques étudiées, elles sont par ailleurs ré-excitables in vivo. Nous présentons une synthèse originale pour l'élaboration de " petites " NPs de ZnGa2O4 :Cr3+ par voie hydrothermale assistée par chauffage micro-onde qui peut être suivi d'un traitement thermique. Les caractérisations avancées des propriétés de luminescence persistante et la structure fine du matériau a montré une corrélation directe entre la luminescence et l'ordre local des cations dans la structure (répartition et distorsion des sites cationiques). Ainsi, nous avons montré l'effet bénéfique d'une calcination sans frittage sur l'amélioration des propriétés de luminescence. Nous avons également mis en évidence le gain apporté par l'ajout d'un codopant comme l'ion Bi3+ ou la modification de la matrice avec la substitution d'une partie des ions Ga3+ par des ions Ge4+. Les limites d'optimisation de ce matériau étant atteinte, une toute nouvelle voie a été ouverte dans cette thématique en dopant la matrice avec des ions Ni2+ pour déplacer la luminescence persistante dans le domaine du proche infrarouge. L'exploitation de cette nouvelle fenêtre pour l'imagerie optique devrait permettre d'imager plus profond dans les tissus avec un meilleur rapport signal/bruit. / This thesis aims to develop persistent luminescent nanoparticles (NPs) for optical imaging in the deep red and near infrared range. Their use has a clear advantage as the irradiation step can be performed before injection, avoiding tissue stress and other autofluorescence phenomena. The chemical compositions studied are also re-excitable in vivo. We propose an original way of synthesis for the elaboration of “small” ZnGa2O4:Cr3+ NPs. Hydrothermal synthesis assisted by microwave heating followed by a heat treatment is used to obtain the NPs. The extensive characterization of the persistent luminescence properties and of the material’s fine structure showed a direct correlation between luminescence and local cation order in the structure (distribution and distortion of cationic sites). Thus, we have shown the benefits of a heat treatment without sintering on the improvement of luminescence properties. We have also highlighted the enhancement provided by the addition of a codopant such as Bi3+ ions or the modification of the matrix by substituting a part of Ga3+ ions by Ge4+ ions. The optimization limits of this material being reached, doping the matrix with Ni2+ ions to move the persistent luminescence in the near infrared range, opens a new pathway in this research field. Exploiting this new window for optical imaging should allow imaging deeper into tissue with a better signal-to-noise ratio.