Na presente tese de doutorado, foram exploradas possibilidades para a aplicação de nanopartículas (NPs) metálicas plasmônicas (fenômenos ópticos intensificados) em processos de fotocatálise e em células solares de Si. Estratégias foram exploradas para a imobilização das NPs plasmônicas em TiO2 Degussa P25 (mistura anatase:rutila 4:1) para captação da radiação eletromagnética UV/visível e somente visível em processos fotocatalíticos; e de NPs de Cu em células solares de Si para processos de fotoconversão, contribuindo com a compreensão dos fenômenos de intensificação local de energia mediados pelas NPs, o qual ainda está em debate no cenário científico. Compósitos de P25+NPs Ag de diferentes arquiteturas (fios, esferas e fotorreduzidas), de P25+NPs Ag recoberta com uma camada de SiO2 e de P25+NPs Au foram desenvolvidos. A caracterização dos materiais foi realizada por meio de técnicas de espectroscopia UV-VIS, IR e Raman, área superficial, DRX e de microscopia eletrônica de varredura e de transmissão. Os efeitos das propriedades plasmônicas dessas nanopartículas foram avaliados na eficiência de fotodegradação de três corantes (alizarina vermelha S, vermelho do Congo e fenossafranina) e de fenol. Todos os materiais plasmônicos apresentaram bom desempenho catalítico, aumentando consideravelmente a velocidade e a porcentagem de fotodegradação sob radiação UV/visível, mas principalmente sob radiação visível (onde a fotodegradação catalisada por P25 é limitada). A comparação entre a fotodegradação de fenol pelo compósito P25+NPs Ag esferas e P25+NPs Ag@SiO2 permitiu concluir que a transferência de carga não é o fenômeno que governa o aumento da eficiência catalítica em comparação à fotodegradação catalisada por P25. O fenômeno de intensificação de radiação eletromagnética localizada por meio de LSPR foi observado também em células solares de silício de primeira geração (wafer) contendo NPs de Cu imobilizadas em sua superfície. Aumentos na densidade de corrente de curto-circuito de cerca de 8 % na região acima de 750 nm e de até 16% na potência destas células solares foram observados. / In this thesis, we explored possibilities for the application of metallic plasmonic nanoparticles (NPs) resulting in intensified optical phenomena processes in photocatalysis and Si solar cell. Different strategies were explored for the immobilization of plasmonic NPs on TiO2 Degussa P25 (mixture anatase: rutile 4:1) to capture electromagnetic radiation UV / visible and visible only in photocatalytic processes; and Cu NPs in Si solar cell for photoconversion processes, contributing with the understanding of the phenomena related to the localized ressonance energy mediated by NPs, which is still under debate in the scientific field. Composites of P25+Ag NPs of various architectures (wires, spheres and photoreduced) P25+Ag NPs coated with a layer of SiO2 and P25+Au NPs were developed. The material characterization was performed by means of UV-VIS, IR and Raman spectroscopies, BET surface area, XRD and scanning and transmission electron microscopy. The effects of plasmonic nanoparticles properties were evaluated in the photodegradation efficiency of three textile dyes (Alizarin Red S, Congo red and phenosafranine) and phenol. All plasmonic materials showed good catalytic performance, greatly increasing the kinetic and percentage of photodegradation under UV/visible, but mostly under visible light (where the photodegradation catalyzed by P25 is limited). The comparison between the photodegradation of phenol by P25+Ag sphere NPs and P25+Ag@SiO2 composite showed that the charge transfer is not the phenomenon that governs the increase in catalytic efficiency when compared to the photodegradation catalyzed by P25. The phenomenon of near field intensification through LSPR was also observed in first generation Si solar cells (wafer) containing Cu NPs immobilized on its surface. Increases in the short-circuit current density of about 8% in the region above 750 nm and up to 16% in the power of these solar cells were observed.

Na presente tese de doutorado, foram exploradas possibilidades para a aplicação de nanopartículas (NPs) metálicas plasmônicas (fenômenos ópticos intensificados) em processos de fotocatálise e em células solares de Si. Estratégias foram exploradas para a imobilização das NPs plasmônicas em TiO2 Degussa P25 (mistura anatase:rutila 4:1) para captação da radiação eletromagnética UV/visível e somente visível em processos fotocatalíticos; e de NPs de Cu em células solares de Si para processos de fotoconversão, contribuindo com a compreensão dos fenômenos de intensificação local de energia mediados pelas NPs, o qual ainda está em debate no cenário científico. Compósitos de P25+NPs Ag de diferentes arquiteturas (fios, esferas e fotorreduzidas), de P25+NPs Ag recoberta com uma camada de SiO2 e de P25+NPs Au foram desenvolvidos. A caracterização dos materiais foi realizada por meio de técnicas de espectroscopia UV-VIS, IR e Raman, área superficial, DRX e de microscopia eletrônica de varredura e de transmissão. Os efeitos das propriedades plasmônicas dessas nanopartículas foram avaliados na eficiência de fotodegradação de três corantes (alizarina vermelha S, vermelho do Congo e fenossafranina) e de fenol. Todos os materiais plasmônicos apresentaram bom desempenho catalítico, aumentando consideravelmente a velocidade e a porcentagem de fotodegradação sob radiação UV/visível, mas principalmente sob radiação visível (onde a fotodegradação catalisada por P25 é limitada). A comparação entre a fotodegradação de fenol pelo compósito P25+NPs Ag esferas e P25+NPs Ag@SiO2 permitiu concluir que a transferência de carga não é o fenômeno que governa o aumento da eficiência catalítica em comparação à fotodegradação catalisada por P25. O fenômeno de intensificação de radiação eletromagnética localizada por meio de LSPR foi observado também em células solares de silício de primeira geração (wafer) contendo NPs de Cu imobilizadas em sua superfície. Aumentos na densidade de corrente de curto-circuito de cerca de 8 % na região acima de 750 nm e de até 16% na potência destas células solares foram observados. / In this thesis, we explored possibilities for the application of metallic plasmonic nanoparticles (NPs) resulting in intensified optical phenomena processes in photocatalysis and Si solar cell. Different strategies were explored for the immobilization of plasmonic NPs on TiO2 Degussa P25 (mixture anatase: rutile 4:1) to capture electromagnetic radiation UV / visible and visible only in photocatalytic processes; and Cu NPs in Si solar cell for photoconversion processes, contributing with the understanding of the phenomena related to the localized ressonance energy mediated by NPs, which is still under debate in the scientific field. Composites of P25+Ag NPs of various architectures (wires, spheres and photoreduced) P25+Ag NPs coated with a layer of SiO2 and P25+Au NPs were developed. The material characterization was performed by means of UV-VIS, IR and Raman spectroscopies, BET surface area, XRD and scanning and transmission electron microscopy. The effects of plasmonic nanoparticles properties were evaluated in the photodegradation efficiency of three textile dyes (Alizarin Red S, Congo red and phenosafranine) and phenol. All plasmonic materials showed good catalytic performance, greatly increasing the kinetic and percentage of photodegradation under UV/visible, but mostly under visible light (where the photodegradation catalyzed by P25 is limited). The comparison between the photodegradation of phenol by P25+Ag sphere NPs and P25+Ag@SiO2 composite showed that the charge transfer is not the phenomenon that governs the increase in catalytic efficiency when compared to the photodegradation catalyzed by P25. The phenomenon of near field intensification through LSPR was also observed in first generation Si solar cells (wafer) containing Cu NPs immobilized on its surface. Increases in the short-circuit current density of about 8% in the region above 750 nm and up to 16% in the power of these solar cells were observed.

The doctoral thesis "Low frequency modes from small nanoparticles (metal nanocrystals) to large nanospheres (viruses): an inelastic light scattering study" is dedicated to investigations of the acoustic properties of different nano-objects : small metal nanoparticles and nanocrystals (D < 30 nm) and large colloid/viral particles (D _ 200 nm). Inelastic light Raman/Brillouin scattering is used as the main research tool to probe the nanoparticle vibrations and to determine their elastic and mechanical parameters. In the first chapter, the well developed theory of elasticity is used to perform a qualitative and nomenclatural analysis of solid sphere vibrations ; several theoretical models allowing to describe the nanoparticle vibrational behavior within a surrounding medium and how the eigenvibrations are modified due to inner crystalline elastic anisotropy are discussed. The second chapter is dedicated to the description of the physics of inelastic light scattering which derives from the fluctuations of the polarizability induced by vibrations. Two types of inelastic light scattering are described : Brillouin scattering which results from the coupling of incident light (photon) with acoustic propagative waves (phonon) in a bulk substance and Raman scattering which is a result of the interaction between an incident photon and localized vibrations, hence nanoparticle vibrations in the present study. As essential in our study, the detailed description and principles of operation of the spectroscopic tools (tandem Fabry-Perot) used to perform these very low frequency inelastic light scattering spectroscopies (between 3 and 300 GHz typically) are given. The third chapter focuses on the study of low frequency modes from small metallic nanoparticles. Three systems are investigated : AuAg and Cu nanoparticles embedded in a vitreous matrix and Au nanocrystals deposited on a surface. The AuAg system allowed to study a notably rich Raman spectrum featuring contributions from fundamental modes and high order harmonics. The experimental data were found to compare rather well with theoretical predictions, thereby providing more insight into the essential ingredients of Raman scattering from nanoparticle modes. The study of deposited Au nanocrystals allowed characterizing the effect of nanocrystalline quality which results in a partial lifting of degeneracy of the nanoparticle modes due to elastic anisotropy. Investigating the wavelength dependence of the Raman spectrum allows a differentiation between single nanocrystals and multiply twinned nanoparticles. Both embedment effects and nanocrystallinity effects are integrated in the study of Cu nanoparticles grown in a glass matrix, where the influence of annealing conditions on the produced nanoparticles was investigated. It was shown that different annealing temperatures [...] result in very different low frequency Raman profiles. [...] The forth chapter reports on the exploration of the possible use of the low frequency inelastic light scattering probe in the characterization of large viruses, as illustrated in the third chapter for small nanoparticles. In order to address the change of the light selection rules as the wavelength of the exciting light becomes comparable to the size of the nanoparticles, the behaviors of the viruses are compared to those of polymer colloids. Ultra Small Angle X-ray Scattering and Atomic Force Microscopy are used to first ensure the comparableness of viruses and polystyrene colloids in terms morphologies. On the basis of the inelastic light scattering data obtained for PS colloids [...], we discuss the difficult interpretation in termsof eigenmodes of the virus counterparts.

The work presented in this thesis shows how tunneling spectroscopy techniques can be applied to metallic nanoparticles to obtain useful information about fundamental physical processes in nanoscopic length scales. At low temperatures, the discrete character of the energy spectrum of these particles, allows the study of spin-polarized current via resolved "electron-in-a-box" energy levels. In samples consisting of two ferromagnetic electrodes tunnel coupled to single aluminum nanoparticles, spin accumulation mechanisms are responsible for the observed spin-polarized current. The observed effect of an applied perpendicular magnetic field, relative to the magnetization orientation of the electrodes, indicates the suppression of spin precession in such small particles. More generally, in the presence of an external non-collinear magnetic field, it is the local field "felt" by the particle that determines the character of the tunnel current. This effect is also observed in the case where only one of the electrodes is ferromagnetic. In contrast to the non-magnetic case, ferromagnetic nanoparticles exhibit a much more complex energy spectrum, which cannot be accounted for, using the simple free-electron picture. It will be shown that interactions between quasi-particle excitations due to sequential electron tunneling and spin excitations in the particle are likely to play an important role in the observed temperature/voltage dependence of magnetic hysteresis loops.

Structurer les matériaux composites, pour au moins une des phases, à l’échelle nanométrique, c’est-à-dire former des matériaux nanocomposites, est une voie pour optimiser nombre de leurs propriétés. Le domaine de la propulsion et des propergols n’échappe pas à cette règle. C’est dans ce contexte que s’est déroulée cette thèse sur la synthèse de nanocomposites ‘nanoparticules métalliques/polymère’ en milieux fluides supercritiques (FSCs). Les principales étapes rencontrées dans l’élaboration de nanocomposites en milieu scCO2 ont été étudiées : i) Etude thermodynamique des systèmes polymère/scCO2, ii) Mesure de leur viscosité et iii) Synthèse de nanoparticules inorganiques dans des polymères en milieux FSCs. De plus, une partie importante de la thèse a concerné la synthèse de nanoparticules d’aluminium en milieux fluides supercritiques en vue de leur intégration dans des matrices polymères pour des applications propergols. / Structuring composite materials, at least for one phase, at the nanometer scale, that is to say synthesize nanocomposite materials, is an interesting way to optimize their properties. The field of propulsion and propellants follows this rule. This is the context of this PhD dealing with the synthesis of nanocomposites constituted of metallic nanoparticles and polymer in supercritical fluids. The main steps for the formation of nanocomposites in scCO2 have been studied: i) Thermodynamical study of polymer/scCO2 systems, ii) Viscosity measurements of polymer/scCO2 systems and iii) Synthesis of inorganic nanoparticles in polymers in supercritical fluids. Moreover, an important part of this work has concerned the synthesis of aluminum nanoparticles in supercritical fluids in order to incorporate them in polymer matrixes for applications to propellants.

Neste trabalho são apresentadas a síntese e caracterização das propriedades luminescentes dos sistemas vítreos TeO2-ZnO e TeO2-ZnO-PbO-Na2O dopados com íons de európio e térbio contendo nanopartículas (NPs) metálicas de prata, ouro e cobre, para aplicações em dispositivos fotônicos. Estes vidros possuem uma larga região de transmissão (350-6500 nm), elevada estabilidade química, resistências mecânica e térmica, baixa energia de fônon (em torno de 700 cm-1) e alto índice de refração (~ 2,0). Por meio de medidas de absorção óptica foi observada a incorporação dos íons de terras-raras na forma trivalente, responsável pelo fenômeno de luminescência nos vidros e a presença de bandas de absorção relacionadas à ressonância dos plasmons superficiais (RPS), localizadas em aproximadamente 490 nm (no caso das NPs de prata), em 500 nm (no caso das NPs de ouro) e em torno de 800 nm (no caso das NPs de cobre). A caracterização das NPs metálicas foi realizada por meio da Microscopia Eletrônica de transmissão auxiliada pelas técnicas de difração de elétrons e espectrometria de energia dispersiva (EDS) e permitiu a observação de NPs metálicas, cristalinas e de diversos formatos e tamanhos. As medidas de emissão foram realizadas excitando as amostras em 405 nm para as dopadas com Eu3+ e 377 nm para as amostras dopadas com Tb3+, por meio de um espectrômetro de fluorescência, com lâmpada de Xenon de pulsos de 2 a 3 s. Foram medidas bandas de emissão associadas à emissão do Eu3+ em 580 nm, 590 nm, 614 nm, 650 nm e 695 nm devidas às transições 5D07FJ (com J = 0 até 4). A banda situada em 614 nm, associada a uma transição de dipolo-elétrico é a mais intensa, por ser mais sensível às mudanças do campo local provocado pela presença das NPs metálicas. Para as amostras dopadas com Tb3+ foram observadas emissões em 485 nm, 550 nm, 590 nm e 623 nm, associadas às transições 5D47FJ (com J = 6 até 3), sendo a emissão em 550 nm associada também a uma transição de dipolo-elétrico e portanto a mais sensível às alterações do campo local provocado pela presença das NPs metálicas. Para as amostras codopadas com íons de Eu3+ e Tb3+, foram observados aumentos significativos da luminescência referente à emissão em 614 nm na presença de NPs de prata. A obtenção de aumento da luminescência dos íons de Eu3+ somente pela transferência de energia proveniente do Tb3+ não é um mecanismo trivial. Entretanto, foi observado em amostras preparadas com diferentes concentrações de íons aceitadores e doadores e intensificada também na presença de NPs de prata. Os aumentos ocorridos na luminescência são provavelmente causados pelo aumento do campo local nas proximidades dos íons de terras-raras e por processos de transferência entre as NPs metálicas e os íons de terras-raras. Nestes casos a distância entre os íons de terras-raras e as NPs está compreendida entre 5 nm e 20 nm. Portanto, a presença das NP desempenha um papel importante para o aumento da luminescência, permitindo o desenvolvimento de novos materiais com aplicações em nanofotônica. / This work presents the synthesis and characterization of luminescent properties of vitreous systems TeO2-ZnO e TeO2-ZnO-PbO-Na2O doped with ions of europium and terbium containing silver, gold and copper nanoparticles (NPs), for applications in photonic devices. These glasses have a large window transmission (350-6500 nm), chemical stability, mechanical and thermal resistance, low phonon energy (around 700 cm-1) and high refraction index (~2,0). The optical absorption measurement showed the incorporation of rareearths ions in the trivalent form, responsible for the luminescence phenomenon in the glasses and the presence of absorption bands related to the surface plasmons resonance (SPR), located in approximately 490 nm (in the case of silver NPs) in 500 nm (in the case of gold NPs) and around 800 nm (in the case of copper NPs). The characterization of the metallic NPs was perfomed with transmission electron microscopy (TEM) with the aid of electron diffraction and energy dispersive spectroscopy techniques that allowed the observation of metallic NPs, crystalline with several shapes and sizes. The measurements were made through with excitation of 405 nm for samples doped with Eu3+ and 377 nm for samples doped with Tb3+, using a fluorescence spectrometer, with Xenon lamp with pulses varying from 2 to 3 s. The bands associated to Eu3+ emission were measured at 580 nm, 590 nm, 614 nm, 650 nm and 695 nm due to the transitions 5D07FJ (with J = 0 to 4). The band situated at 614 nm related to electric dipole transition is the most intense because it is sensitive to changes in the local field, caused by the presence of metallic NPs. For samples doped with Tb3+ it was observed emissions at 485 nm, 550 nm, 590 nm and 623 nm, associated with the transitions 5D47FJ (with J = 6 to 3) being the 550 nm emission also related to electric dipole transition and consequently the most sensitive to changes in the local field, caused by the presence of metallic NPs. For the samples codoped with Eu3+ and Tb3+ ions it was observed significative enhancement of the luminescence at 614 nm emission in the presence of silver NPs. The achievement of the enhancement of the luminescence of Eu3+ ions only by energy transfer from Tb3+ is not a trivial mechanism. However, it was observed in samples prepared with different concentrations of acceptor and donors ions and intensified in the presence of NPs silver. The enhancement of the luminescence is probably caused by the increase of the local field around the rare earth ions and by processes of energy transfer between the metallic NPs and the rare earth ions. In these cases the distance between the rare earth ions and the metallic NPs ranges from 5 to 20 nm. Thus, the presence of metallic NPs plays an important role for the enhancement of the luminescence, allowing the development of new materials with application in photonic.

O presente trabalho apresenta a produção e a investigação das propriedades ópticas de guias de onda vítreos baseados no sistema PbO-GeO2, codopados com íons de érbio de itérbio e contendo nanopartículas metálicas de ouro e prata, para aplicações como dispositivos fotônicos na terceira janela de telecomunicações (1530 nm). Os guias de onda foram obtidos por meio de processos convencionais utilizados em microeletrônica usando a técnica RF Magnetron Sputtering para deposição do material sobre uma estrutura do tipo PEDESTAL. Os primeiros guias produzidos apresentaram irregularidades laterais próximas ao núcleo que contribuíram para o aumento das perdas. Mudanças no processo de fabricação como a diminuição da espessura da máscara de cromo usada para a corrosão do SiO2, etapa adicional para a corrosão e a diminuição da espessura do guia de onda proporcionaram redução das perdas por propagação e aumento do ganho óptico em ~50% estimado em 6,0 dB/cm, em 1530 nm, para um guia de onda de 80 µm de largura. Entretanto, as dificuldades para medir guias com menores larguras levaram-nos a produzir guia de onda PEDESTAL utilizando SiO2 como máscara de corrosão do silício que permitiram redução significativa das irregularidades lateral; neste caso foi possível medir a perda e o ganho em guias com largura de até 1 µm. Acrescenta-se que guias de 6 µm tiveram aumento do ganho em 50% na presença de nanopartículas de ouro, atingindo 7,5 dB/cm para potência de bombeamento de 60 mW, portanto inferior à utilizada para o caso do guia sem nanopartículas de ouro, cuja saturação do ganho ocorreu em 100 mW. Guias com nanopartículas de prata foram também produzidos, obtendo-se ganho máximo de 4,0 dB/cm para um guia de 80 µm. Os resultados obtidos nos guias de onda PbO-GeO2 codopados com Er3+ e Yb3+ são promissores e mostram possibilidade de aplicação dos guias de onda como amplificadores ópticos na terceira janela de telecomunicações. / This work presents the production and investigation of optical properties of erbium and ytterbium ions codoped PbO-GeO2 waveguides, containing metallic nanoparticles (NPs), for applications as photonic devices in the third window Telecommunications (1530 nm). The waveguides were obtained by microelectronics conventional processes and by RF Magnetron Sputtering technique using a pedestal type structure. The first pedestal waveguides presented irregulaties, in the lateral region, that contributed to the propagations losses enhancement. Changes in the fabrication process, as the decrease of the chromium used for SiO2 corrosion, additional step for the etching and decrease of the waveguide thickness provided reduction of the propagation losses and enhancement of the optical gain of about 50%; so we obtained 6.0 dB/ cm, at 1530 nm, for 80 µm waveguide width. The difficulty to measure waveguides with smaller width lead us to develop PEDESTAL waveguides using SiO2 as silicon mask for corrosion enabled the decrease of the roughness nearby the core. In this case it was possible to measure propagation losses and gain for waveguides width of 1 µm. It was obtained enhancement of 50 % for the waveguides with 6 µm width in the presence of gold NPs and the result was 7.5 dB/cm at 60 mW pumping power; for the case of the waveguide without gold NPs gain saturation occurred at 100 mW. Waveguides with silver NPs were also produced and the maximum gain was of 4.0 dB/cm for 80 µm. These results show the possibility of using Er3+and Yb3+ codoped PbO-GeO2 pedestal type waveguides as optical amplifiers in the third telecommunications window.

Les matériaux poreux basés sur les polymères font l’objet de recherches nombreuses et variées depuis leur découvertes et jusqu’à aujourd’hui encore. Leurs propriétés uniques et remarquables, comme par exemple une fonctionnalisation aisée ou une large gamme de porosité accessibles, couplées à leur faible coût de production les rendent attrayant pour de nombreuses applications. Parmi elles, la catalyse supportée est en plein essor, spécialement depuis l’avènement des nanoparticules. Durant ce travail de thèse, nous avons développé différents matériaux polymères pouvant servir de support, se focalisant majoritairement sur trois types de matériaux : des matériaux polymères massiques, des matrices polymères poreuses en capillaire ainsi que des polystyrènes poreux provenant de la dégradation sélective de copolymères diblocs.Dans un premier temps, différentes stratégies ont été employées pour l’immobilisation et la génération de nanoparticules sur les matériaux massiques. L’un a consisté en la synthèse d’un monomère contenant un pont disulfure qui, après réduction, a permis la libération de groupement thiol permettant l’accrochage de nanoparticules d’or. La seconde a consisté à réduire de manière originale les nanoparticules en utilisant un gaz, l’hydrogène. Dans un seconde partie, la synthèse de différentes matrices polymères dans des capillaires a été réalisée. Tout d’abord, une matrice déjà connue de la littérature à base de N-acryloxysuccinimide a été utilisée, après modification via thiol-ène et substitution nucléophile par différentes amines, pour immobiliser des nanoparticules de cuivre ainsi que d’or, respectivement. D’autre part, une nouvelle matrice à partir de carbonate cyclique aura, elle, été utilisée après modification, pour l’immobilisation de nanoparticules de platine. Enfin à partir de copolymères diblocs possédant différentes jonctions entre chaque bloc (un pont disulfure ainsi qu’un acétal), différents polystyrènes poreux ont été obtenus. Les copolymères possédant une jonction acétal à lui été utilisé pour l’immobilisation de nanoparticules d’or, permettant la mise en place des réactions de réduction de nitro, d’homocouplage boronique ainsi que de la mise en cascade de ces deux réactions / Porous materials based on polymers have been the subject of intense and various researches since their discovery until now. Their unique and remarkable properties, like their easy functionalization or their large porosity range reachable for instance, coupled with their low production cost makes them attractive for numerous applications. Among them, supported catalysis is booming, especially since the rising of nanoparticles. During this Ph.D. contribution, we have developed different polymeric materials, which could be used as support, focusing mainly onto three types: bulky materials, porous polymeric matrixes into capillaries and porous polystyrene arising from the selective degradation of diblocks copolymers.Firstly, different strategies have been employed for the immobilization and the generation of nanoparticles onto bulk materials. On the one hand, the synthesis of a monomer, bearing a disulphide bridge which can, after a reduction step, free a thiol moiety allowing us to anchor gold nanoparticles. On the other hand, a new route to reduce nanoparticle has been employed using gaseous hydrogen. In another part, the syntheses of different polymeric matrixes into capillaries have been made. First, we used an already known matrix, based on N-acryloxysuccinimide -after modification step via thiol-ene reaction and nucleophilic substitution by amines- to anchor copper or gold nanoparticles, respectively. Also, a new matrix based on cyclic carbonates has been used, after modification, to immobilized platinum nanoparticles. Finally, starting from diblocks copolymers possessing different junctions between both blocks (disulphide bridge or acetal), porous polystyrenes have been obtained. The copolymers bearing an acetal have been implemented to immobilized gold nanoparticles, catalysing several reactions like nitro reduction, boronic homocoupling as well as the cascade reaction of both

Orientador: Ana Flavia Nogueira / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-14T13:13:51Z (GMT). No. of bitstreams: 1 Conturbia_GiovannideLimaCabral_M.pdf: 7472586 bytes, checksum: 9ede857037431127443d2bed95bd1ccc (MD5) Previous issue date: 2009 / Resumo:Células solares orgânicas têm despertado atenções devido ao baixo custo de produção e dos materiais utilizados, bem como devido à versatilidade química e de propriedades eletrônicas e ópticas dos semicondutores orgânicos. A eficiência atual atinge 5% (100 mWcm). Nanotubos de carbono encontram suas aplicações nessas células ora como eletrodos transparentes ora como material receptor de elétrons. Nesse trabalho, foi realizada a modificação química de nanotubos de carbono de única camada com grupos tióis, visando a incorporação de nanopartículas metálicas ou semicondutoras. O material de partida, bem como os nanotubos modificados, foi caracterizado por Espectroscopia Raman, Espectroscopia de Fotoelétron por Raios-X, Análise Térmica e Microscopia Eletrônica de Transmissão de Alta Resolução. Foi necessário um pós-tratamento (térmico e lavagens com diversos solventes) para que pudéssemos obter nanotubos individuais e funcionalizados. O pós-tratamento também possibilitou um aumento na fotocorrente dos dispositivos em comparação com o dispositivo sem nanotubos de carbono. A incorporação de nanopartículas de ouro no sistema P3HT/fulereno acresceu a fotocorrente e o fator de preenchimento dos dispositivos. Estudos de caracterização através de difração de raios-X, espectroscopia UV-visível e microscopia de força atômica, indicam que esse aumento está relacionado a uma mudança na morfologia do sistema, aumentando a cristalinidade do polímero e também ao efeito plasmônico com a adição das nanopartículas. Imagens de microscopia eletrônica de transmissão revelaram que as nanopartículas de ouro estão distribuídas tanto na fase polimérica quanto na fase contendo moléculas de fulereno / Abstract: Organic solar cells have attracted attention due to their low costs of production and materials used, as well as the chemical versatility and good electronic and optical properties of organic semiconductors. The current efficiency reaches 5% (100 mWcm). Carbon nanotubes materials can be applied in these cells as both transparent electrode or as electron acceptor materials. In this work, the chemical modification of single wall carbon nanotubes was carried out attaching thiol groups, aiming the incorporation of semiconductor or metallic nanoparticles. The raw material and the modified nanotubes were characterized by Raman Spectroscopy, X-ray Photoelectron Spectroscopy, Thermal Analysis and High Resolution Transmission Electron Microscopy. A post-treatment (thermal and washing with different solvents) was necessary in order to obtain single functionalized nanotubes. The post-treatment also allowed an increase in the photocurrent of the devices compared to the device without carbon nanotubes. The incorporation of gold nanoparticles in the P3HT/fullerene system increased the photocurrent and the fill factor of the devices. X-Ray diffraction, UV-vis Spectroscopy and Atomic Force Microscopy studies reveal that such increase can be related to the plasmonic effect and also to a change in the morphology, increasing polymer crystallinity after incorporation of the gold nanoparticles. High resolution transmission microscopy images showed that the nanoparticles are distributed between both polymer and fullerene phase. / Mestrado / Físico-Química / Mestre em Química

Scanning transmission electron microscopy is one of the essential techniques suitable not only for imaging of nanostructures, but also for various kinds of spectroscopy and, as it was recently demonstrated, nanomanipulation. In this thesis, we deal with an interaction of fast electrons and metallic spherical nanoparticles, specifically aluminium and gold nanospheres. First, we present both analytical and numerical calculations of electron energy loss spectra and their analysis for different parameters. The main part of the thesis is devoted to theoretical calculations of forces acting on the nanosphere due to the electron passing in its close proximity. Based on our novel results revealing a time evolution of the mechanical force, we also propose a possible mechanism responsible for the nanoparticle movement in electron microscopes.