Submitted by Geandra Rodrigues (geandrar@gmail.com) on 2017-12-20T13:20:23Z No. of bitstreams: 1 israelnovaesdemoura.pdf: 1420476 bytes, checksum: 6634c39e49385490d2f7b019fb451af1 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-12-21T11:59:42Z (GMT) No. of bitstreams: 1 israelnovaesdemoura.pdf: 1420476 bytes, checksum: 6634c39e49385490d2f7b019fb451af1 (MD5) / Made available in DSpace on 2017-12-21T11:59:42Z (GMT). No. of bitstreams: 1 israelnovaesdemoura.pdf: 1420476 bytes, checksum: 6634c39e49385490d2f7b019fb451af1 (MD5) Previous issue date: 2017-08-04 / O objetivo deste trabalho foi avaliar a caracterização e eficácia de diferentes técnicas da espectroscopia de fluorescência na detecção de adulterações em formulações de Whey Protein concentrado (WPC) em pó, a partir de sua mistura com substâncias de diferentes origens. Foram estudados dois diferentes lotes de WPC provenientes do mesmo fornecedor. Adulterações foram realizadas a partir da adição individual de Cafeína (Tratamento 1), Creatina (Tratamento 2) e Lactose (Tratamento 3) a 30% (m/m) em WPC e submetidas às análises de espectroscopia de fluorescência estacionária e resolvida no tempo, utilizando-se os comprimentos de onda de excitação de 275 e 335 nm. Quando excitadas a 275 nm, as amostras apresentaram pico de emissão a 335 nm aproximadamente, com uma banda de emissão em torno de 380 nm, característica apenas na amostra contendo cafeína, enquanto lactose e creatina não induziram alterações no espectro do WPC. Quando excitadas a 335 nm, as amostras apresentam picos de emissão com máximo em 425 e 470 nm, sem diferenciação por simples observação do espectro. Análise da distância Euclidiana evidenciou que, quando excitadas a 275 nm, os espectros completos dos tratamentos 2 e 3 foram semelhantes ao Controle 1 enquanto o Tratamento 1 foi diferente. Já na excitação a 335 nm todos os espectros foram semelhantes. Análise de Componentes Principais (PCA) confirmou a diferenciação do Tratamento 1 a 275 nm mas foi inconclusiva com a excitação de 335 nm, porém determinou pontos de interesse para estudos das derivadas dos espectros. Com as derivadas, foi possível a diferenciação entre os Tratamentos 2 e 3 nos dois comprimentos de onda, com enfoque em comprimentos de ondas específicos que podem ser decisivos na diferenciação das adulterações. Em relação a espectroscopia resolvida no tempo, o Tratamento 1 demonstrou valores da intensidade média do tempo de vida de emissão superior aos tratamentos 2 e 3 nos dois comprimentos de onda de excitação empregados. A adulteração com cafeína foi realizada na amostra Controle 2 e foi observado resultado semelhante quando comparada ao Controle 1. De maneira geral, a aplicação das técnicas de espectroscopia de fluorescência estacionária e resolvida no tempo possibilitou a caracterização das amostras utilizadas no estudo. Além disso, possibilitou a observação de diferenças entre as amostras controles e aquelas adulteradas, especialmente a adicionada de cafeína e excitada no comprimento de onda 275 nm, com ajuda de ferramentas matemáticas. Os resultados aqui obtidos corroboram com o fato de que as técnicas empregadas podem ser importantes na detecção de fraudes em produtos lácteos. / The objective of this work was to evaluate the characterization and efficacy of different fluorescence spectroscopy techniques in the detection of adulterations in formulations of Whey Protein Concentrate (WPC) powder, from its mixture with substances of different origins. Two different batches of WPC from the same supplier were studied. Adulterations were performed from the individual addition of Caffeine (Treatment 1), Creatine (Treatment 2) and Lactose (Treatment 3) at 30% (w / w) in WPC and subjected to stationary fluorescence spectroscopy and time-resolved fluorescence, using the excitation wavelengths of 275 and 335 nm. When excited at 275 nm, the samples showed an emission peak at approximately 335 nm, with an emission band around 380 nm, characteristic only in the sample containing caffeine, while lactose and creatine did not induce alterations in the WPC spectrum. When excited at 335 nm, the samples showed peak emission at 425 and 470 nm, without differentiation by simple observation of the spectrum. Euclidean distance analysis showed that, when excited at 275 nm, the complete spectra of treatments 2 and 3 were similar to Control 1 while Treatment 1 was different. Regarding the excitation at 335 nm, all spectra were similar. Principal Component Analysis (PCA) confirmed the differentiation of Treatment 1 at 275 nm but it was inconclusive with 335 nm excitation, however, it determined points of interest for spectra derivative studies. With the derivatives, it was possible to differentiate between Treatments 2 and 3 in the two wavelengths, focusing on specific wavelengths that can be decisive in the differentiation of adulterations. In relation to time resolved fluorescence spectroscopy, Treatment 1 demonstrated values of the mean emission lifetime higher over Treatments 2 and 3 at the two excitation wavelengths employed. The caffeine adulteration was performed in the Control 2 sample and a similar result was observed when compared to Control 1. In general, the application of stationary and time resolved fluorescence spectroscopy techniques allowed the characterization of the samples used in the study. In addition, it made possible the observation of differences between the control and adulterated samples, especially the one with caffeine added and excited at the wavelength 275 nm, with the help of mathematical tools. The results obtained here corroborate the fact that the techniques employed may be important in the detection of fraud in dairy products.

Betalaínas são alcalóides coloridos e com alta capacidade antioxidante que são encontrados em plantas e fungos. A biossíntese destes produtos naturais baseia-se na conversão enzimática da L-tirosina em ácido betalâmico e na condensação aldimínica deste com aminoácidos. A semissíntese de betalaínas naturais para aprofundar o estudo desta classe de pigmentos estimulou o desenvolvimento de betalaínas artificiais, incluindo derivados funcionais. Uma betalaína cumarínica foi criada para ser usada como sonda fluorescente para marcação de Plasmodium falciparum em glóbulos vermelhos. Esta Tese de Doutorado apresenta a semissíntese e estudo de três betalaínas cumarínicas (cBeets) e uma carboestiril-betalaína (csBeet). Procurou-se estabelecer relações entre as estruturas destes compostos e suas propriedades físico-químicas e fotofísicas como ponto de partida no desenvolvimento de uma nova classe de betalaínas funcionais. São apresentados dados sobre a lipofilicidade, estabilidade frente à hidrólise, potencial redox, absorção de um e dois fótons e fluorescência. Interações intermoleculares destes compostos foram investigadas por medidas de fluorescência em misturas binárias de solventes polares, albumina sérica bovina e micelas reversas de AOT em heptano/água. / Instituto de Química, Universidade de São Paulo, São Paulo, 2017. Betalains are colorful alkaloids with high antioxidant capacity that are found in plants and fungi. The biosynthesis of these natural products is based on the enzymatic conversion of L-tyrosine into betalamic acid and aldimine condensation thereof with amino acids. The semisynthesis of natural betalains improved the knowledge on this class of pigments and stimulated the development of artificial betalains, including functional derivatives. A coumarinic betalain was created to be used as a fluorescent label for Plasmodium falciparum on red blood cells. This Doctoral Thesis presents the semisynthesis and study of three coumarin betalains (cBeets) and one carbostyril betalain (csBeet). It was sought to establish relationships between the structures of these compounds and their physical-chemical and photophysical properties as a starting point in the development of a new class of functional betalains. Data on lipophilicity, hydrolysis stability, redox potential, one- and two-photon absorption and fluorescence are presented. Intermolecular interactions of these compounds were investigated by fluorescence measurements in binary polar solvent mixtures, bovine serum albumin and AOT reverse micelles in heptane/water.

Este estudo reúne os principais resultados de fluorescência estática e resolvida no tempo sobre a interação da porfirina meso-tetrakis (4-metilpiridil), na forma de base livre (TMPyP) e complexada com Zn2+ (ZnTMPyP), com vesículas de fosfolipídio. Adicionalmente foram utilizadas as técnicas de potencial zeta e espalhamento de luz dinâmico (DLS, do inglês \"dynamic light scattering\"). As vesículas de fosfolipídio foram formadas por dois conjuntos de fosfolipídios: saturados e insaturados. O primeiro grupo é formado pela mistura dos fosfolipídios zwiteriônico 1,2-dipalmitoil-sn-glicero-3-fosfocolina (DPPC) e aniônico 1,2-dipalmitoil-sn-3-glicero-[fosfo-rac-(1- glicerol)] (DPPG), a diferentes razões molares. Os estudos utilizando tais sistemas foram realizados abaixo (25oC) e acima (50oC) da temperatura de transição de fase gel-líquido cristalino destes fosfolipídios (~ 41oC). O segundo grupo é formado pela mistura dos fosfolipídios zwiteriônico 1-palmitoil-2-oleoil-sn-glicero-3-fosfocolina (POPC) e aniônico 1-palmitoil-2-oleoil-sn-glicero-3-fosfo(1-rac-glicerol) (POPG). Como a transição de fase destes dois fosfolipídios ocorre a temperaturas negativas, todos os experimentos foram realizados a 25oC (vesículas no estado líquido cristalino). Todos os sistemas foram preparados através do método de extrusão para a obtenção de vesículas grandes unilamelares (LUV, do inglês \"large unilamellar vesicles\"). As análises dos dados de fluorescência indicaram que a atração eletrostática entre os substituíntes (positivamente carregados) das porfirinas TMPyP e ZnTMPyP e o grupo das cabeças polares (camada de Stern) das vesículas de fosfolipídio desempenha um papel fundamental na associação da porfirina. A distribuição da TMPyP entre o meio aquoso (tampão) e as vesículas de fosfolipídio foi evidenciada pela coexistência de um tempo de vida de fluorescência mais curto (~ 5 ns) e outro mais longo (~ 9-11 ns), respectivamente. Baseado nos valores das constantes pré-exponenciais, estudos adicionais mostram que a distribuição acima é afetada pela concentração de sal na solução. Os resultados de supressão de fluorescência com o supressor iodeto de potássio (KI) indicaram que ambas porfirinas estão localizadas, preferencialmente, na região da camada de Stern. Este resultado foi confirmado pelos estudos de potencial zeta e de DLS, os quais mostraram uma neutralização parcial das cargas negativas na superfície das vesículas devido à associação da porfirina. / This study presents time-resolved and steady-state fluorescence results on the interaction of the meso-tetrakis (4-methylpyridil) porphyrin, in free base form (TMPyP), and complexed with Zn2+ (ZnTMPyP), with phospholipid vesicles. Zeta potential and dynamic light scattering (DLS) techniques were also used. Phospholipid vesicles were formed by two phospholipid systems: saturated and unsaturated. The first group is a mixture of zwiterionic dipalmitoyl-sn-glycero-3-phosphocoline (DPPC) and anionic 1,2-dipalmitoyl-sn-3-glycero-[phospho-rac-(1-glycerol)] (DPPG) phospholipids, at different molar ratios. Measurements were performed bellow (25oC) and above (50oC) the main gel-liquid crystalline phase transition temperature (~ 41oC). The second group is constituted by a mixture of zwiterionic 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocoline (POPC) and anionic 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho(1-rac-glycerol) (POPG) phospholipids, at different molar ratios. Since the gel-liquid crystalline phase transition of these phospholipids occurs at a very low temperature value, all experiments were performed at 25oC (liquid crystalline state vesicles). All phospholipid systems were prepared through the extrusion method in order to obtain large unilamellar vesicles (LUV). The fluorescence data analyses indicated that the electrostatic attraction between the porphyrin substituents (positively charged) and the polar head groups of the phospholipid vesicles (Stern layer) plays an important role on the porphyrin binding affinity. The distribution of TMPyP between the aqueous medium (buffer) and the phospholipid vesicles was characterized by the coexistence of a shorter (~ 5 ns) and a longer (~ 9-11 ns) fluorescence lifetimes, respectively. Based on the pre- exponential values, additional time-resolved experiments showed a redistribution of the porphyrin at increasing salt concentration. The quenching studies, using potassium iodide (KI) as quencher, indicated that both TMPyP and ZnTMPyP are preferentially located at the Stern layer region. This result is in agreement with the zeta potential and DLS findings, which demonstrated a partial neutralization of the negative charges at the vesicle surface due to the porphyrin association.

Orientador: René Alfonso Nome Silva / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-25T09:25:13Z (GMT). No. of bitstreams: 1 Ferbonink_GuilhermeFerreira_M.pdf: 3339040 bytes, checksum: ef20418e159acb6b4683d177155e28be (MD5) Previous issue date: 2014 / Resumo: Nos últimos anos, várias descobertas vêm sendo realizada sobre como características intrínsecas de um dado sistema podem afetar a transferência eletrônica de energia. Um dos objetivos desta pesquisa é estudar experimentalmente como a estrutura vibrônica pode afetar a transferência eletrônica de energia em moléculas orgânicas segundo o modelo de Förster. Utilizando um sistema molecular com sobreposição espectral sobre bandas vibrônicas bem definidas, podemos verificar experimentalmente que o abaixamento da intensidade de emissão do doador unicamente nos comprimentos de onda de absorção do receptor caracteriza transferência de energia pelo modelo emissivo. Abaixamento da intensidade integrada de emissão caracteriza transferência de energia pelo mecanismo de Förster. A taxa de transferência de energia pelo mecanismo de Förster foi mais significativa quando a sobreposição espectral ocorre nas bandas vibrônica 0-1,0-2 ao invés da banda 0-0. Na segunda parte do trabalho realizado, aplicamos a técnica de absorção transiente para o estudo de nano prismas de ouro depositados sobre dois substratos diferentes. Neste trabalho, nós descrevemos a preparação e caracterização de matrizes isoladas de nanoprismas triangulares de ouro sobre o vidro contendo uma camada de ITO por litografia de nanoesferas. O espectro de absorção linear de Au / vidro e Au / ITO / vidro exibe ressonância de plásmon de superfície em 800 nm e 870 nm, com um deslocamento para o vermelho de 70 nm associado ao índice de refração de ITO. Foram realizadas medidas de espectroscopia de uma única cor de bombeio e prova com resolução temporal de 100 fs em comprimentos de onda inferiores a ressonância, em ressonância, e acima da ressonância de plásmon de superfície para cada um destes dois sistemas. A dinâmica ultra-rápida em ambos os sistemas pode ser bem descrita com um modelo que contabiliza o espalhamento elétron-elétron, o acoplamento elétron-fônon, e oscilações acústicas no término do resfriamento da estrutura de ouro. Os resultados para as nanopartículas de ouro, para cada um dos comprimentos de onda são bem descritos como tendo índice de refração complexo com dependência do comprimento de onda, que modula os sinais de bombeio e prova medidos / Abstract: Structure-property relationships for electronic energy transfer have been investigated in recent years. One of the goals of the present research is to perform an experimental study vibronic structure effects in electronic energy transfer between small organic molecules according to Forster¿s model. We have chosen organic molecules with well-defined spectral overlap between vibronic bands, which enabled us to experimentally characterize a decrease in donor emission intensity at the acceptor absorption wavelengths thereby indicating radiative energy transfer. A decrease in the emission integrated intensity characterizes energy transfer by the Forster mechanism. Forster energy transfer rates were higher when the spectral overlap involved 0-1 and 0-2 vibronic bands rather than 0-0 band. In the second part of this work, we have employed ultrafast transient absorption spectroscopy to investigated gold nano prisms deposited over two different substrates: Au over glass (Au/glass) and Au over ITO deposited on glass (Au/ITO/glass). In the present work, we describe the preparation and characterization of these two samples employing the nanosphere lithography technique. The linear absorption spectra of Au/glass and Au/ITO/glass respectively show surface plasmon resonances at 800 nm and 870 nm, with a 70nm redshift attributed to the ITO refractive index. We have performed femtosecond one-color pump-probe measurements with 100 fs time resolution below the surface plasmon resonance, at resonance, and above the surface plasmon resonance for each of these two systems. For both systems, the ultrafast dynamics can be well described with a model that takes into account electron-electron scattering, electron-phonon coupling, phonon-phonon coupling and acoustic damping. The wavelength-dependence observed can be explained in terms of the sample frequency-dependent complex refractive index which modulates the measured pump-probe signals / Mestrado / Físico-Química / Mestre em Química

Les technologies VLSI (« Very large Scale Integration ») font partie de notre quotidien et nos besoins en miniaturisation sont croissants. La densification des transistors occasionne non seulement des difficultés à localiser les défauts dits « hard » apparaissant durant les phases de développement (débug) ou de vieillissement, mais aussi l’apparition de comportements non fonctionnels purs du composant liées à des défauts de conception. Les techniques abordées dans ce document sont destinées à sonder les circuits microélectroniques à l’aide d’un outil appelé émission de lumière dynamique (Time Resolved Imaging - TRI) à la recherche de comportements anormaux au niveau des timings et des patterns en jeu dans les structures. Afin d’aller plus loin, cet instrument permet également la visualisation thermographique en temps résolue de phénomènes thermiques transitoires au sein d’un composant. / VLSI ("Very Large Scale Integration") technologies are part of our daily lives and our miniaturization needs are increasing. The densification of transistors not only means trouble locating the so-called "hard defects" occurring during the development phases (debug) or aging, but also the appearance of pure non-functional behaviors related to component design flaws. Techniques discussed in this document are intended to probe the microelectronic circuits using a tool called dynamic light emission (Time Resolved Imaging - TRI) in search of abnormal behavior in terms of timings and patterns involved in structures. To go further, this instrument also allows viewing thermographic time resolved thermal transients within a component.

On considère les paquets d'ondes hydrodynamiques comme mécanismes de génération de bruit des jets subsoniques. Cette approche résulte tout d'abord de l'analyse de données numériques - DNS d'une couche de mélange (Wei et Freund 2006) et LES d'un jet à Mach 0,9 (Daviller 2010) - permettant de déterminer les propriétés des sources en termes de compacité, d'intermittence et de structure azimutale. L'identification d'un rayonnement intermittent associé aux modifications des structures cohérentes des écoulements permet de proposer un modèle de paquet d'onde pour représenter ce phénomène dans l'analogie de Lighthill, dont l'enveloppe présente des variations temporelles d'amplitude et d'étendue spatiale. Celles-ci sont tirées de données de vitesse de simulations numériques de jets subsoniques, et un accord de l'ordre de 1,5dB entre le champ acoustique simulé et le modèle confirme sa pertinence. L'exploration du concept proposé est ensuite poursuivie expérimentalement, avec des mesures de pression acoustique et de vitesse de jets turbulents subsoniques, permettant la décomposition des champs en modes de Fourier azimutaux. On observe l'accord des directivités des modes 0, 1 et 2 du champ acoustique avec le rayonnementd'un paquet d'onde. Les modes 0 et 1 du champ de vitesse correspondent également à des paquets d'onde, modélisés comme des ondes d'instabilité linéaires à partir des équations de stabilité parabolisées. Finalement, des corrélations de l'ordre de 10% entre les modes axisymétriques de vitesse dans le jet et de pression acoustique rayonnée montrent un lien clair entre les paquets d'onde et l'émission acoustique du jet. / Hydrodynamic wavepackets are studied as a sound-source mechanism in subsonic jets. We first analyse numerical simulations to discern properties of acoustic sources such as compactness, intermittency and azimuthal structure. The simulations include a DNS of a two-dimensional mixing layer (Wei and Freund 2006) and an LES of a Mach 0.9 jet (Daviller 2010). In both cases we identify intermittent radiation, which is associated with changes in coherent structures in the flows. A wave-packet model that includes temporal changes in amplitude and axial extension is proposed to represent the identified phenomena using Lighthill's analogy. These parameters are obtained from velocity data of two subsonic jet simulations, and an agreement to within 1.5dB between the model and the acoustic field of the simulations confirms its pertinence. The proposed mechanism is then investigatedexperimentally, with measurements of acoustic pressure and velocity of turbulent subsonic jets, allowing the decomposition of the fields into azimuthal Fourier modes. We find close agreement of the directivities of modes 0, 1 and 2 of the acoustic field with wave-packet radiation. Modes 0 and 1 of the velocity field correspond also to wavepackets, modelled as linear instability waves using parabolised stability equations. Finally, correlations of order of 10% between axisymmetric modes of velocity and far-field pressure show the relationship between wavepackets and sound radiated by the jet.

Pour l'étude d'une structure solide ou d'un matériau, l'analyse expérimentale permet d'obtenir des grandeurs mécaniques qui permettent de comprendre leurs comportements ou encore de valider des résultats issus d'une simulation numérique. Ces grandeurs peuvent être de différentes natures (contraintes, déformations...) et être localisées de différentes manières dans l'espace (2D, 3D) et dans le temps (statique, dynamique). Le bilan des techniques actuelles d'analyse expérimentale en mécanique des solides révèle un besoin concernant l'acquisition d'une structure en tous points avec une résolution élevée à la fois spatialement et temporellement. L'objectif des travaux menés au cours de cette thèse est le développement d'une nouvelle technique d'acquisition capable d'acquérir un volume de matière de quelques centimètres de côté en moins d'une seconde avec une précision spatiale inférieure à 0.1mm. Les volumes obtenus doivent avoir une qualité suffisamment élevée pour être couplés à la technique de Corrélation d'Images Volumiques (DVC) permettant d'obtenir les déplacements ainsi que le tenseur des déformations de Green-Lagrange complet au coeur de la matière. Un nouveau procédé d'acquisition baptisé Optical Rotating Scanning Tomography (ORST) et basé sur le découpage optique a été développé. Après l'avoir décrit mathématiquement, un système spécifique synchronisé avec une caméra rapide a été conçu. La méthode a été appliquée sur deux essais mécaniques : traction continue et contact entre un galet roulant et un bloc. L'analyse des résultats a montré que l'ORST est capable d'analyser l'évolution des champs de déformations à la fois au coeur du volume et résolue en temps. / To study of a solid structure or a material, an experimental analysis can be used to get mechanical fields in order to understand the mechanical behaviour or to validate simulation results. Different kind of fields can be obtained (stress, strain) in different spatial (2D, 3D) or temporal referential (static, dynamic). Current techniques are not able to acquire the whole volume of a structure with a high spatial and temporal resolution. The objective of this work is to develop a new volume acquisition technique able to capture a volume with a characteristic edge size of several centimetres in less than 1 second with a spatial accuracy less than 0.1mm. Reconstructed volumes need to have a good quality to be used with the Digital Volume Correlation (DVC) in order to provide displacement fields and the full Green-Lagrange tensor in the whole volume. A new acquisition technique called Optical Rotating Scanning Tomography (ORST) based on the optical scanning technique has been developed. A mathematical description has been achieved and then a special device has been manufactured. This device is synchronized with a high speed CCD camera in order to perform time-resolved acquisition. This new technique has been used to study two mechanical tests. The first is a traction test with a continuous loading, and the second concerns a wheel rolling over a solid bloc. Experimental results of these applications show that ORST technique is able to analyse displacement and strain fields in the whole volume and in a time-resolved way.

Les microcavités optiques présentent de hauts facteurs de qualité, c'est pourquoi ces systèmes sont d'un grand intérêt pour la conception de lasers à bas seuil, ou encore, pour l'étude du régime de couplage fort. En revanche, ces systèmes sont soumis à la limite de diffraction de la lumière, et donc les modes qu'ils supportent ont une extension spatiale ne pouvant être en deçà de l'échelle de la longueur d'onde. Dans ce manuscrit de thèse, nous nous intéressons aux systèmes plasmoniques parce qu'ils supportent des modes confinés à l'échelle nanométrique. En premier lieu, nous étudions une microcavité plasmonique planaire, constituée de deux miroirs plasmoniques qui piègent les ondes de surface au sein du système. Nous sondons spatialement les modes de la cavité en mesurant le temps de vie de fluorescence de molécules individuelles dispersées au sein du système. Puis, nous nous intéressons au confinement en 3 dimensions de modes supportés par des nanoparticules métalliques sphériques. Nous discutons de la définition du volume modal basée sur le calcul du confinement d'énergie autour de la particule. Ensuite, nous étudions l'exaltation de fluorescence d'ions de terres rares au sein d'une particule plasmonique de configuration coeur-coquille. Enfin, nous perturbons la photodynamique d'émission d'une source de photon unique en approchant à proximité l'extrémité d'une pointe plasmonique / Optical microcavities exhibit high resonance quality, so that, they are of key interest for the design of low-threshold lasers or for achieving strong coupling regime. But, such systems support modes whose the volume remain diffraction limited.In this manuscript, we are interested in their plasmonic counterparts because they support confined modes at the sub-wavelength scale. First, we study an in-plane plasmonic cavity which is the transposition of 1D optical cavity to surface wave. We characterize the cavity by measuring the fluorescence lifetime of dye molecules deposited inside.Then, we are interested in 3-dimension mode confinement achieved by spherical metal nanoparticles. We discuss on the definition of the mode volume used in cavity quantum electrodynamic and based on the calculation of energy confinement around the particle. We also simulate the fluorescence enhancement of rare-earth ions embedded inside core-shell plasmonic particles. Finally, we disturb the photodynamic emission of a single-photon source by puttingthe extremity of a plasmonic tip nearby the emitter

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La capacité de photo-commuter les propriétés physico-chimiques des matériaux fonctionnels grâce à des transitions de phase induites par la lumière, ouvre des perspectives fascinantes pour diriger un matériau vers un nouvel état hors équilibre thermique. Cependant, il est fondamental de comprendre tous les phénomènes élémentaires, habituellement cachés dans une moyenne statistique lors des transformations à l'équilibre. Les études résolues en temps représentent une approche unique pour accéder à l'évolution des différents degrés de liberté du système et connaître les processus élémentaires mis en jeu lors de la commutation macroscopique. Les matériaux à transition de spin (SCO) sont d'un intérêt particulier car ce sont des systèmes photo-réversibles. Ces matériaux sont aussi des prototypes photomagnétiques et photochromiques qui commutent entre deux états de différente multiplicité de spin, nommés bas spin (LS) et haut spin (HS). Dans ce travail de thèse, nous étudions les dynamique ultrarapides électroniques et structurales de cette classe de solides moléculaires, en soulignant l'importance d'utiliser des sondes complémentaires sensibles à différents degrés de liberté. Les commutation photo-induite entre états de spin est ultra-rapide et initialement localisée à l'échelle moléculaire, où le couplage électron-phonon active des vibrations cohérentes intramoléculaires. Un transfert d'énergie ultra-rapide de la molécule au réseau, via un couplage phonon-phonon, permet de piéger efficacement le système dans le nouvel état photo-induit. Cependant, dans les solides moléculaires, l'excès d'énergie libérée de la molécule excitée résulte dans un aspect complexe multi-échelle impliquant plusieurs degrés de liberté à des échelles de temps différentes. Dans ce travail de thèse, nous avons étudié la dynamique multi-étape hors équilibre d'un système SCO présentant une brisure de symétrie entre la phase HS et la phase intermédiaire (IP) où une mise en ordre à longue distance des états HS et LS des molécules résulte en la formation d'une onde de concentration de spin (SSCW). La diffraction des rayons X résolue en temps combinée avec des études de spectroscopie optique donnent une description complète de la dynamique hors-équilibre de la SSCW hors-équilibre en mesurant l'évolution temporelle des deux paramètres d'ordre décrivant le système. / The ability to photo-switch physical/chemical properties of functional materials through photo induced phase transition opens fascinating perspectives for driving the material towards new state out of thermal equilibrium. However, it is fundamental to disentangle and understand all the dynamical phenomena, otherwise hidden in statistically averaged macroscopic transformations. Arguably, time-resolved studies are unique approach to access the necessary information on the multiple degrees of freedom and elementary processes involved during the macroscopic switching. As photo-reversible molecular switches, spin crossover (SCO) materials are of particular interest. These photomagnetic and photochromic prototype materials undergo metastable photoinduced phase transition between two states of different spin multiplicity, namely low-spin (LS) and high-spin (HS). In this PhD work it will be presented the ultrafast electronic and structural dynamics of SCO molecular solids emphasizing the importance of using complementary probes sensitive to different degrees of freedom. The photoinduced spin state switching concerns initially only an ultrafast, but localized, molecular response which through strong electron-phonon coupling activates coherent intra-molecular vibrations. An ultrafast energy transfer from the molecule to the lattice, via phonon-phonon coupling, allows an efficient trapping of the system in the new photoinduced state. However in molecular solids, the excess of energy released from the absorber molecule results in a complex multi-scale aspect involving several degrees of freedom at different time scales. In this contest, we investigated the multi-step out-of equilibrium dynamics of a SCO system undergoing symmetry breaking between the HS phase and the intermediate (IP) phase where a long range ordering of HS and LS molecules results in a spin state concentration wave (SSCW), analogous to charge or spin density waves. Combined time-resolved X-ray diffraction and optical spectroscopy studies provide a complete overview of the out-of-equilibrium thermodynamics of the SSCW, investigating how the two order parameters describing the system evolve in time.