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Ogurtsov, Alexander, Olga Bliznjuk, and Nataliia Masalitina. "Crystal size effect in polaritonic luminescence from atomic cryocrystals." Thesis, Hyogo University, 2019. http://repository.kpi.kharkov.ua/handle/KhPI-Press/44703.
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Shastri, Vasant. "Single-photon-counting technique for luminescence spectra and decay measurements." Ohio : Ohio University, 1987. http://www.ohiolink.edu/etd/view.cgi?ohiou1183060409.
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McFee, Christopher James. "The use of an imaging photon detector for luminescence dating." Thesis, University of Oxford, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.296940.
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Balasubramanian, Haribhaskar. "Two photon luminescence from quantum dots using broad and narrowband ultrafast laser pulses." [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-2020.
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Ghenuche, Petru Virgil. "Probing the near-field optical response of plasmon nanostructures with two-photon luminescence microscopy." Doctoral thesis, Universitat Politècnica de Catalunya, 2009. http://hdl.handle.net/10803/22737.
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Esta tesis describe el diseño, la fabricación y la caracterización óptica de sistemas plasmónicos resonantes capaces de confinar y aumentar campos de luz en la escala manométrica. En primer lugar, se utilizaron modelos numéricos 3D para diseñar diferentes geometras de nanoestructuras plasmónicas acopladas, a través del cálculo de la respuesta óptica de su campo lejano y cercano. Sobre la base de estas simulaciones se fabricaron las nanoestructuras por litografía de haz electrónico. Se puso especial énfasis en el aumento de la resolución y la optimización de la reproducibilidad de parámetros críticos como la forma de las partículas y el gap entre ellas. Por último, se empleó espectroscopía de campo lejano combinada con espectroscopía de luminiscencia inducida por dos fotones (TPL) para sondar la respuesta óptica local de las geometrías optimizadas.
Hemos centrado nuestra atención en diferentes tipos de estructuras metálicas: dímeros, antenas con gap, conjuntos finitos de partículas en cadenas y en forma de estrella. Los dímeros tienen una fuerte amplificación del campo en su gap nanométrico por el acoplamiento en campo cercano de sus resonancias plasmonicas dipolares. Análogamente, antenas con gap, formadas por dos barras de oro adyacentes que soportan resonancias multipolares, pueden acoplar de manera eficiente la luz y concentrarla en volúmenes pequeños. Se ha demostrado que cadenas finitas de partículas son buenos candidatos para guiar la luz a través de secciones transversales por debajo de la longitud de onda y aquí demostramos que también se pueden utilizar como nanolentes capaces de concentrar la luz en su extremo. La distribución del campo cercano en conjuntos de partículas de oro en forma de estrella presenta una fuerte dependencia con la polarización del campo incidente que puede ser explotada para dirigirse dinámicamente a nano-objetos.
La espectroscopía de campo lejano de conjuntos de dímeros y de cadenas finitas de partculas se comparó con la espectroscopía de TPL.
Nuestro principal resultado es mostrar que la TPL es preferentemente sensible a los campos locales, permitiendo evaluar características espectrosc ópicas que no podrían resolverse de otro modo. A fin de superar las limitaciones de las medidas de conjuntos, en una segunda etapa se dedicó un considerable esfuerzo a construir y optimizar un montaje óptico para medir la señal de TPL de estructuras únicas. El uso de la micro-espectroscopía de TPL permitió obtener mapas espectrales de los modos de antenas aisladas con resolución espacial.
Como se predijo mediante cálculos, hemos sido capaces de visualizar directamente, en la resonancia, la señal de TPL amplificada dentro del gap. Nuestros resultados muestran cómo las medidas de TPL pueden compararse directamente con la distribución de la cuarta potencia del campo local calculado. Mediante el análisis de la evolución de la señal de TPL en función de la longitud de onda incidente en el gap y en las extremidades de la antena tenemos más conocimiento sobre el mecanismo físico detrás de la resonancia de la antena. Finalmente, la microscopía de TPL se utilizó para sondar el campo cercano para diferentes orientaciones de la polarización lineal incidente sobre los conjuntos de partículas en forma de estrella. Se demuestra que, a diferencia del espectro de dispersión, la distribución de TPL en la estructura depende drásticamente del estado de polarización incidente.
Nuestro estudio aporta una contribución significativa al campo de la óptica de plasmones, proponiendo nuevas geometrías para confinar de manera eficiente los campos ópticos a la escala nanometrica, aportando un profundo conocimiento sobre el uso de micro-espectroscopa de TPL como sonda óptica local. Nuestros resultados tendrán importancia en aplicaciones tales como espectroscopía mejorada, biosensores y la interacción luz-materia, donde se necesita evaluar el campo experimentado por una pequeña cantidad de materia cercana a la nanoestructura.<br>This thesis describes the design, fabrication and the optical characterization of plasmon-resonant systems able to confine and enhance light fields down to the sub-wavelength scale. Extensive 3D numerical modeling was first used to design different geometries of coupled plasmonic nanostructures through the calculation of their far-field and near-field optical response. On the basis of simulations, the nanostructures were fabricated by e-beam lithography and thin film deposition.
Special efforts were devoted to increasing the resolution and optimizing the reproducibility of critical parameters such as particle shape and interparticle gaps. Finally, far-field spectroscopy combined with two-photon induced luminescence (TPL) spectroscopy was used to probe the local optical response of the optimized architectures.
We focused our attention on different families of structures: metal dimers, bar antennas, finite chains of nanoparticles and star-like particle arrangements. Particle dimers feature strong field enhancements in their sub-wavelength gap due to near-field coupling of their dipolar localized plasmon resonances. Based on the same physics, gap antennas, formed by two adjacent gold bars supporting multipolar resonances can efficiently couple to propagating light and concentrate it into tiny volumes. While finite particle chains were previously shown by other authors to be good candidates to guide light through subwavelength cross-sections, we show here that they can also be used as efficient nanolenses able to concentrate light at their extremity.
Finally, the near-field distribution in star-like arrangements of gold nanoparticles exhibits a strong dependence with the incident field polarization which can be exploited for dynamical optical addressing of nano-objects.
We have compared the far field spectroscopy of large ensembles of dimers and finite chains to TPL spectroscopy. Our main result is to show that TPL is preferentially sensitive to local fields and that it enables the assessment of spectroscopic features which cannot be resolved otherwise. In order to overcome the limitations of measurements on large ensembles a considerable effort was dedicated to mounting and optimizing an optical set-up enabling TPL measurement of single structures.
Using the developed TPL micro-spectroscopy, spatially resolved spectral mode mapping on single resonant gap-antennas was achieved. As predicted by calculations, we were able to directly visualize at resonance the strongly enhanced TPL signal within the gap. Our results show how TPL scans can be directly compared with the convoluted distribution of the fourth power of the calculated local mode field.
By monitoring the evolution with the incident wavelength of the TPL signal within the gap and at the antenna extremities we got further insight in the physical mechanism behind the buildup of the antenna’s resonance.
Finally, TPL microscopy was used to probe the local fields under different orientations of the incident linear polarization near star-like arrangement of gold disks. It is shown that, unlike the scattering spectrum, the TPL distribution over the structure is found to depend drastically on the incident polarization state.
Our study brings a significant contribution to the field of Plasmon optics by proposing novel geometries able to efficiently confine optical fields down to the nanometric scale, but also by providing deep insight into the use of TPL microspectroscopy to probe their local optical response. Our findings are foreseen to be important in applications such as enhanced spectroscopy, bio-sensing and enhanced light-matter interaction, where one needs to assess the actual field experienced by small amounts of matter.
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Bourrellier, Romain. "Luminescence at Defects in h-BN : Excitons at Stacking Faults and Single Photon Emitters." Thesis, Paris 11, 2014. http://www.theses.fr/2014PA112285/document.
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Dans les dernières années nombre de matériaux lamellaires à dimensions réduites ont démontré des propriétés optiques remarquables. Cependant, la plupart des études ont porté sur le système parfait et le rôle des défauts en tant que centres optiques actifs restent encore largement inexploré. Le nitrure de bore hexagonal (h-BN) est l'un des candidats les plus prometteurs pour les dispositifs émetteurs de lumière dans la région de l’UV lointain, présentant une forte émission excitonique à 5,8 eV. Cependant, émission n’apparaît uniquement que dans des monocristaux très purs qui peuvent difficilement être obtenus que par des procédés de synthèse complexes. Les échantillons ordinaires de h-BN présentent des spectres d'émission plus complexes qui ont été généralement été attribuée à la présence de défauts structuraux. Malgré un grand nombre d'études expérimentales jusqu'à présent il n'a pas été possible d'attribuer cette émission additionnelle à des défauts structuraux bien définis. Nous abordons ici cette question fondamentale en adoptant une approche théorique et expérimentale combinant une technique de cathodoluminescence nanométriquement résolu avec une caractérisation structural résolu atomiquement par microscopie électronique a transmission et de l'état de l'art de simulations excitoniques. Très récemment, l'équipe d'Orsay a mis au point un système de détection de cathodoluminescence intégré au sein d'un microscope électronique à transmission à balayage. Cette expérience unique est maintenant en mesure de fournir des spectres d'émission complet avec une résolution aussi faible que quelques dizaines de MeV associés à une taille de sonde électronique du nanomètre. Une image hyper-spectrale cathodoluminescence peut donc être enregistrée en parallèle avec une image HAADF. La cathodoluminescence résolu au nanomètre sur quelques-couche chimiquement exfoliée de h-BN a montré que les spectres d'émission sont fortement inhomogènes dans les feuillets individuels. Les pics d'émission à proximité de l'exciton libre apparaissent dans des régions étendues. Les examens complémentaires par microscopie électronique à transmission à haute résolution permettent d'associer ces raies d'émission avec des défauts étendue dans le cristal tels que les défauts d'empilement et les plis des facetter. Au moyen de calculs ab-initio dans le cadre de la « Many Body perturbation theory » (GW) et l'équation de Bethe-Salpeter nous fournissons une description détaillée de la structure électronique et la réponse spectroscopique du nitrure de bore hexagonal en présence de défaut d’empilements. En particulier, nous montrons un bon accord avec les résultats expérimentaux, les excitons supplémentaires sont associées à des changements de symétrie locaux qui se produisent par des fautes d'empilement dans le cristal. Ce résultat sera ensuite étendu à des nanotubes de BN à parois multiples. Des émissions supplémentaires qui apparaissent à l'intérieur du gap présentent une localisation spatiale élevée, typiquement inférieure à 100 nm, et par conséquent ils peuvent être liés à des défauts ponctuels individuels. Lorsqu’ils sont adressés individuellement à travers une sonde électronique très ciblé, ils pourraient avoir un caractère d’émetteur de photon unique. Cette hypothèse a été récemment confirmée par des expériences combinant notre système de cathodoluminescence avec un interféromètre Handburry-Brown et Twiss (HBT)<br>Within the latest years number of layered materials at reduced dimensions have demonstrated remarkable optical properties. However most studies focused on perfect system and the role of defects as optical active centers remain still largely unexplored. Hexagonal boron nitride (h-BN) is one of the most promising candidates for light emitting devices in the far UV region, presenting a single strong excitonic emission at 5.8 eV. However, a single line appears only in extremely pure mono-crystals that can hardly be obtained only though complex synthesis processes. Common h-BN samples present more complex emission spectra that have been generally attributed to the presence of structural defects. Despite a large number of experimental studies up to now it was not possible to attribute specific emission features to well identify defective structures. Here we address this fundamental question by adopting a theoretical and experimental approach combining few nanometer resolved cathodoluminescence techniques with high resolution transmission electron microscopy images and state of the art quantum mechanical simulations. Very recently, the Orsay team has developed a cathodoluminescence detection system integrated within a scanning transmission electron microscope. This unique experimental set up is now able to provide full emission spectra with a resolution as low as few tens of meV associated with an electron probe size of one nanometer. A cathodoluminescence hyper-spectral image can thus be recorded in parallel with an HAADF image. Nanometric resolved cathodoluminescence on few-layer chemically exfoliated h-BN crystals have shown that emission spectra are strongly inhomogeneous within individual flakes. Emission peaks close to the free exciton appear in extended regions. Complementary investigations through high resolution transmission electron microscopy allow to associate these emission lines with extended crystal deformation such as stacking faults and folds of the planes. By means of ab-initio calculations in the framework of Many Body Perturbation Theory (GW) approximation and Bethe-Salpeter equation) we provide an in-depth description of the electronic structure and spectroscopic response of bulk hexagonal boron nitride in the presence of extended morphological modifications. In particular we show that, in a good agreement with the experimental results, additional excitons are associated to local symmetry changes occurring at crystal stacking faults. These result will then be extended to faceted multiwalled BN nanotubes, they display additional emission at the same energy as characterized within the flakes
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Kang, Ji-Hwan. "Energy transfer enhancement of photon upconversion systems for solar energy harvesting." Thesis, Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45846.
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Photon energy upconversion (UC), a process that can convert two or more photons with low energy to a single photon of higher energy, has the potential for overcoming the thermodynamic efficiency limits of sunlight-powered devices and processes. An attractive route to lowering the incident power density for UC lies in harnessing energy transfer through triplet-triplet annihilation (TTA). To maximize energy migration in multicomponent TTA-assisted UC systems, triplet exciton diffusivity of the chromophores within an inert medium is of paramount importance, especially in a solid-state matrix for practical device integration.
In this thesis, low-threshold sensitized UC systems were fabricated and demonstrated by a photo-induced interfacial polymerization within a coaxial-flow microfluidic channel and in combination with nanostructured optical semiconductors. Dual-phase structured uniform UC capsules allow for the highly efficient bimolecular interactions required for TTA-based upconversion, as well as mechanical strength for integrity and stability. Through controlled interfacial photopolymerization, diffusive energy transfer-driven photoluminescence in a bi-molecular UC system was explored with concomitant tuning of the capsule properties. We believe that this core-shell structure has significance not only for enabling promising applications in photovoltaic devices and photochromic displays, but also for providing a useful platform for photocatalytic and photosensor units.
Furthermore, for improving photon upconverted emission, a photonic crystal was integrated as an optical structure consisting of monodisperse inorganic colloidal nanoparticles and polymer resin. The constructively enhanced reflected light allows for the reuse of solar photons over a broad spectrum, resulting in an increase in the power conversion efficiency of a dye-sensitized solar cell as much as 15-20 %.
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Vezzoli, S. "EXPERIMENTAL STUDY OF NANOCRYSTALS AS SINGLE PHOTON SOURCES." Doctoral thesis, Università degli Studi di Milano, 2013. http://hdl.handle.net/2434/222688.
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Wet-chemically synthesized colloidal nanocrystals are promising single photon emitters at room temperature, due to the strong quantum confinement induced by the small dimensions. However, their applications have been so far limited by two main drawbacks: the blinking of their photo-luminescence and a non-polarized emission.
This manuscript is consecrated to the study of the optical properties of a particular type of colloidal nanocrystals, called dot-in-rod (DR), in which a spherical CdSe core is surrounded by a rod-like CdS shell.
We demonstrate for the first time a suppression of the blinking in thick shell DRs. In contrast to spherical nanocrystals, we show that it can be obtained while keeping a good quality of the single photon emission and a high degree of linear polarization.
A complete room-temperature characterization of the optical, and especially quantum optical, properties of DRs is provided for several geometrical parameters.
In particular, an original approach, based on an ensemble photoluminescence measurement, is developed to assess the quality of a sample of nanocrystals as single photon sources.
By studying single DRs in a confocal microscope, we analyze the influence of the core size and of the shell thickness and length on the photon anti-bunching, radiative lifetime and polarization of the emission.
This systematic study brings a contribution to the understanding of the interaction processes of the confined carriers in semiconductor nanocrystals. The interplay of radiative and non-radiative recombinations and, in particular, the role of the Auger effect in the photo-luminescence blinking and in the emission of non-classical light are deeply investigated.
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Dehlinger, Mael. "XAS-XEOL and XRF spectroscopies using near field microscope probes for high-resolution photon collection." Thesis, Aix-Marseille, 2013. http://www.theses.fr/2013AIXM4048/document.
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Les microscopes en champ proche permettent d'obtenir la topographie d'un échantillon avec une résolution pouvant atteindre la résolution atomique. Les spectroscopies de rayons-X sont des méthodes de caractérisation qui permettent de déterminer la composition et la structure élémentaire de l'échantillon avec une précision inférieure à l'Ångström. Nous avons choisi de coupler ces deux techniques en collectant localement la luminescence visible issue de l'échantillon par la pointe-sonde d'un microscope à force de cisaillement, constituée d'une fibre optique effilée de faible ouverture. Cette technique a été utilisée pour caractériser des échantillons semiconducteurs micro- et nano-structurés afin d'en obtenir simultanément la topographie et la cartographie de luminescence locale. Afin de pouvoir étendre ce concept à d'autres types de matériaux, la faisabilité de la collecte de la fluorescence X locale a été évaluée avec la microsource. Pour cela la fluorescence X émise par un échantillon a été collectée par un capillaire cylindrique équipant un détecteur EDX. L'influence du diamètre du capillaire sur le niveau de signal a été mesurée. Une simulation numérique a été développée afin d'estimer le niveau de signal obtenu en utilisant un capillaire de 1 µm de diamètre et d'optimiser la géométrie du système. En couplant la microscopie en champ proche et l'analyse XRF, à la lumière de ces résultats, il sera possible d'atteindre 100 nm de résolution latérale en environnement synchrotron et moins de 1 µm à l'aide d'une source de laboratoire. Il serait alors possible de sélectionner un objet particulier sur une surface et d'en faire l'analyse élémentaire<br>Scanning Probe Microscopes allow to obtain sample topography up to atomic resolution. X-ray spectroscopies allow elemental and structural analysis of a sample with accuracy better than 1 Å. The lateral resolution is limited by the primary beam diameter, currently a few µm². We have chosen to couple this two technics. Local sample visible luminescence is collected through a low aperture sharp optical fibre, probe of a shear force microscope. This technique was used to characterize microstructured semiconducting samples to achieve simultaneously the surface topography and luminescence mapping. The results were obtained using either synchrotron radiation or a laboratory microsource equipped with a polycapillary lens. To extend this concept to a wider variety of materials, local XRF collection by an EDX detector equipped with a cylindrical X-ray capillary was tested. A cobalt sample irradiated with the microsource was used for technique evaluation. The signal magnitude dependence with the capillary diameter was measured. Modelling and numerical calculations were developed to estimate the signal magnitude that could be detected using a 1 µm diameter capillary. The optimal system geometry was determined. Scanning Probe Microscopy combined to XRF analysis could thereby lead to simultaneous acquisition of sample topography and chemical mapping. The expected lateral resolution using synchrotron radiation is 100 nm while sub 1 µm resolution is realistic with a laboratory source. This technique would allow to point a peculiar micro- or nano-object on the surface and to perform its chemical analysis
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Durantel, Florent. "Mesure de luminescence induite par faisceaux d'ions lourds rapides résolue à l'echelle picoseconde." Thesis, Normandie, 2018. http://www.theses.fr/2018NORMC261/document.
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Nous avons travaillé sur le développement d’un instrument de mesure de la luminescence induite par un faisceau d’ions lourds (nucléons 12) et d’énergie de l’ordre du MeV/nucléons. Basé sur une méthode de comptage de photons uniques obtenus par coïncidences, le dispositif permet d’obtenir sur 16 voies à la fois un spectre en énergie dans le domaine proche UV-visible-proche IR (185-920 nm) et la réponse temporelle sur la gamme ns-µs, avec un échantillonnage de 100 ps. Des mesures en température peuvent être réalisées depuis la température ambiante jusqu’à 30K.Ce travail met particulièrement l’accent sur les méthodes d’extraction des données : Une fois montrée la nécessité de déconvoluer les signaux, on s’intéresse dans un premier temps à évaluer différents profils instrumentaux modélisés et reconstruit à partir de mesures. A cet effet, un travail de caractérisation temporelle de chaque constituant du dispositif est mené. Puis ces profils instrumentaux sont utilisés dans deux méthodes de déconvolution par moindres carrés d’abord puis par maximum d’entropie ensuite.Deux matériaux types sont testés : Le Titanate de Strontium pour l’étude de la dynamique de l’excitation électronique, et un scintillateur plastique commercial, le BC400, pour l’étude du vieillissement et de la baisse des performances en fonction de la fluence. Dans les deux cas on a pu mettre en évidence la présence d’une composante ultra rapide de constante de temps subnanoseconde<br>We developed an instrument for measuring the luminescence induced by a heavy ion beam (nucleons 12) and energy in the range of MeV / nucleon. Based on a single photon counting method obtained by coincidences, the device can provide in the same run a 16-channel energy spectrum in the UV-visible- IR region (185-920 nm) and a time-resolved response in the range of ns up to µs for each channel. Temperature measurements can be performed from room temperature down to 30K.This work places particular emphasis on data extraction methods: Once the need to deconvolve the signals demonstrated the evaluation of different instrument profiles (simulated and reconstructed from measurements) leads to a systematic temporal characterization of each component of the device. Then, these instrumental profiles are used in two deconvolution methods: least squares first followed by maximum entropy method.Two typical materials are tested: the Strontium Titanate for the study of the dynamics of the electronic excitation, and a commercial scintillator, the BC400, for the study of the aging and the decrease of performances with fluence. In both cases, we have been able to highlight the presence of an ultrafast component of subnanosecond time constant
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Andrasik, Stephen James. "Singlet Oxygen Generation Using New Fluorene-Based Photosensitizers Under One- and Two-Photon Excitation." Doctoral diss., University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2210.
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Molecular oxygen in its lowest electronically excited state plays an important roll in the field of chemistry. This excited state is often referred to as singlet oxygen and can be generated in a photosensitized process under one- or two-photon excitation of a photosensitizer. It is particularly useful in the field of photodynamic cancer therapy (PDT) where singlet oxygen formation can be used to destroy cancerous tumors. The use of two-photon activated photosensitizers possesses great potential in the field of PDT since near-IR light is used to activate the sensitizer, resulting in deeper penetration of light into biological tissue, less photo-bleaching of the sensitizer, and greatly improved resolution of excitation. The synthesis and photophysical characterization of new fluorene-based photosensitizers for efficient singlet oxygen production were investigated. The spectral properties for singlet oxygen production were measured at room temperature and 77 K. Two-photon absorption (2PA) cross-sections of the fluorene derivatives were measured by the open aperture Z-scan method. The quantum yields of singlet oxygen generation under one- and two-photon excitation ([Phi][sub Delta] and 2PA[Phi][sub Delta], respectively) were determined by the direct measurement of singlet oxygen luminescence at ≈ 1270 nm. The values of [Phi][sub Delta] were independent of excitation wavelength, ranging from 0.6 - 0.9. The singlet oxygen quantum yields under two-photon excitation were 2PA[Phi][sub Delta] ½[Phi][sub Delta, indicating that the two processes exhibited the same mechanism of singlet oxygen production, independent of the mechanism of photon absorption.<br>Ph.D.<br>Department of Chemistry<br>Sciences<br>Chemistry PhD
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Bui, Ngoc Anh Thy. "Luminescence de complexes de lanthanide par effet d'antenne à deux photons : vers l'imagerie fonctionnelle." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEN021.
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Les ions lanthanides possèdent des propriétés photophysiques particulières, qui ont suscité une forte attention dans le développement de sondes biologiques luminescentes. En effet, les avantages que présentent leurs émissions en raies fines et caractéristiques, ainsi que leurs temps de vie de luminescence longs, permettent diverses applications en imagerie. Cependant, le faible coefficient d’absorption molaire de ces éléments conduit à préférer une excitation par le biais d’une antenne capable de transférer l’énergie au métal.Par ailleurs, l’utilisation de l’absorption biphotonique a montré de nombreux avantages, puisqu’elle permet une excitation de la molécule à une longueur d’onde deux fois plus grande que l’excitation à un photon : cette longueur d’onde peut alors se situer dans la fenêtre de transparence biologique (650 - 1100 nm).Les travaux de cette thèse visent à combiner les avantages des lanthanides avec ceux de l’excitation biphotonique. Les complexes synthétisés sont basés sur une plateforme triazacyclononane substituée par des antennes à deux-photons. Leurs propriétés spectroscopiques à un photon ont été étudiées, et ont alors permis de réaliser des images cellulaires en multiplexing à deux photons utilisant Eu3+ et Tb3+. Des sondes biphotoniques de brillance optimisée ont également été obtenues pour Sm3+, Tb3+ et Dy3+, et appliquées à l'imagerie. L’étude approfondie d’un des complexes de terbium(III) a de plus mis en évidence sa sensibilité à la viscosité. L’analyse des propriétés spectroscopiques de cette sonde a permis d'en rationaliser le comportement photophysique, ouvrant ainsi la voie à des applications originales en imagerie fonctionnelle. Enfin, nous avons montré une internalisation rapide de complexes de lanthanide cationiques de type cyclen ou cyclam par des cellules vivantes, et l'étude de ces nouvelles structures offre de nouvelles perspectives dans le développement de bio-sondes de lanthanides<br>Lanthanide ions demonstrate peculiar photophysical properties that has attracted a substantial attention in the development of luminescent bioprobes. Indeed, the advantages stemming from their sharp and characteristic emissions, as well as their long luminescence lifetimes, enable various imaging applications. However, the weak molar extinction coefficient of these elements results in a preferential excitation through an antenna, which transfers its energy to the metal.On the other hand, biphotonic absorption showed numerous advantages, since excitation of a molecule can be achieved at a wavelength twice as high as using one-photon excitation. This wavelength may therefore reach the optical transparency window (650 - 1100 nm).The work carried out during this PhD thesis aims at combining the advantages of lanthanides with those of biphotonic excitation. The synthesized complexes are based on a triazacyclononane platform substituted with two-photon antennae. Their one-photon spectroscopic properties have been studied, and enabled to perform two-photon multiplexed cellular imaging, using Eu3+ and Tb3+. Biphotonic probes with an optimized brightness have been obtained for Sm3+, Tb3+ and Dy3+, and applied to cell imaging. The thorough study of one of the terbium(III) complexes has moreover displayed evidence of a sensitivity towards viscosity. Analyzing the spectroscopic properties of this probe has therefore allowed to rationalize its photophysical behavior, paving the way for original functional imaging applications. Lastly, a rapid internalization of cationic lanthanide complexes with a cyclen or cyclam framework by living cells has been proved. Thus, the study of these new structures presents new perspectives for the development of lanthanide bioprobes
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Dehlinger, Maël. "XAS-XEOL and XRF spectroscopies using Near-Field Microscope probes for high-resolution photon collection." Phd thesis, Aix-Marseille Université, 2013. http://tel.archives-ouvertes.fr/tel-00880623.
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Les microscopes en champ proche permettent d'obtenir la topographie d'un échantillon avec une résolution pouvant atteindre la résolution atomique. Ces techniques permettent également d'accéder à certaines propriétés locales de la surface telles que le potentiel, l'élasticité, la densité d'états... Ces spectroscopies locales sont de type 'contraste' et ne permettent pas de dresser la cartographie chimique de la surface sans connaissance a priori des éléments qui la composent. Les spectroscopies de rayons-X sont des méthodes de caractérisation puissantes qui permettent de déterminer la composition et la structure élémentaire de l'échantillon avec une précision inférieure à l'Ångström. La résolution latérale est essentiellement limitée par la taille du faisceau primaire, couramment de plusieurs μm². Deux voies sont possibles pour l'améliorer: - réduire l'étendue du faisceau primaire excitateur; - limiter la collecte du rayonnement émis à une portion du volume excité, tout en approchant le détecteur au maximum pour garder un rapport signal/bruit suffisant. C'est cette deuxième option que nous avons choisi de développer. Pour cela nous avons collecté localement la luminescence visible issue de l'échantillon par la pointe-sonde d'un microscope à force de cisaillement, constituée d'une fibre optique effilée de faible ouverture. Cette technique a été utilisée pour caractériser des échantillons semiconducteurs micro- et nano-structurés afin d'en obtenir simultanément la topographie et la cartographie de luminescence locale. Ces résultats ont été obtenus non seulement sur une ligne synchrotron mais également à l'aide d'une microsource de laboratoire équipée d'une lentille polycapillaire. Afin de pouvoir étendre ce concept à d'autres types de matériaux, la faisabilité de la collecte de la fluorescence X locale a été évaluée avec la microsource. Pour cela la fluorescence X émise par un échantillon de cobalt a été collectée par un capillaire cylindrique équipant un détecteur EDX. L'influence du diamètre du capillaire sur le niveau de signal a été mesurée. Une simulation numérique a été développée afin d'estimer le niveau de signal obtenu en utilisant un capillaire de 1 μm de diamètre et d'optimiser la géométrie du système. En couplant la microscopie en champ proche et l'analyse XRF, à la lumière de ces résultats, il sera possible d'atteindre 100 nm de résolution latérale en environnement synchrotron et moins de 1 μm à l'aide d'une source de laboratoire. Il serait alors possible de sélectionner un objet particulier sur une surface et d'en faire l'analyse élémentaire.
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Khaoua, Ibtissame. "Approche quantitative de la bio-chimiluminescence ultrafaible : oxydation et métabolisme Detectivity Optimization to Detect of Ultraweak Light Fluxes with an EM-CCD as Binary Photon Counter Array 3D To 2D Stochastic Concentration of Highly Diluted Light Reveals Ultraweak Chemi- and Bio-Luminescence." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASL005.
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L’émission de lumière par les tissus vivants, probablement liée au métabolisme oxydatif, est connue depuis des décennies, tout comme la luminescence de certaines réactions chimiques très simples en milieu aqueux. Ces phénomènes restent très mal connus en raison de l’extrême faiblesse de lumière produite, appelée de ce fait "luminescence ultrafaible". Dans cette thèse, nous proposons d’abord un dispositif expérimental original pour quantifier avec une très grande sensibilité la luminescence produite par unité de volume de l’échantillon.Le seuil de détection atteint est ≈ 1 photon s−1 cm−3 soit ≈ 2.10−21 M.s−1 . Nous avons pour cela combiné : 1) un environnement d’obscurité maximale, 2) une sphère intégrante de réflexivité extrême pour canaliser au maximum les photons de l’échantillon vers le détecteur, 3) une caméra amplifiée en mode binaire dans le domaine visible (400 − 900) et un modèle statistique conduisant à une détectivité optimale, et 4) une procédure semi-automatique de manipulation dans l’obscurité.Grace à ce dispositif, 1) le seuil de détection est ≈ 9.2 photons s−1cm−2 sur la caméra, soit ≈ 1% du courant d’obscurité, 2) ≈ 12% des photons émis de façon isotrope par l’échantillon sont détectés, 3) la détection des variations de l’intensité lumineuse est optimisée en opérant non pas au maximum du rapport signal à bruit, mais au maximum de détectivité. Nous avons ensuite étudié la luminescence produite par la disproportionation de H2O2 dans l’eau, réaction importante pour le métabolisme et catalysée par les peroxidases, mais essentielle aussi dans l’histoire de la chimiluminescence pour la compréhension fondamentale et ses applications basées sur le luminol. Nous avons quantifié pour la première fois, en absence de tout catalyseur, la luminescence dose-dépendante de la disproportionation dans l’eau pure, avec ≈ 15 photons s−1cm−3 pour [H2O2] = 90 mM. Grace au modèle biologique bien connu des levures Saccharomyces cerevisiae, nous avons mis en évidence un pic de luminescence en culture liquide associé au début de la phase exponentielle, suivi d’une décroissance sur 10 heures. Cette production de lumière représente environ 10−5 par seconde et par cellule.Notre travail permet d’envisager l’étude beaucoup plus quantitative de la luminescence ultrafaible en chimie et en biologie, condition nécessaire pour la com- préhension des mécanismes fondamentaux impliqués et le développement de possibles applications notamment biomédicales<br>It has been known for decades that ultra-weak visible and UV light is emitted by most living tissues due to their oxidative metabolism, as well as by some simple reactions in aqueous medium. However, these phenomena are not well known due to the extreme weakness of the light emission, hence called "ultra-weak" luminescence. In this thesis, we propose an original experimental setup to make extremely sensitive measurements of the luminescence produced by a sample per unit volume.We reached a detection limit of ≈ 1 photon s−1cm−3 which corresponds to ≈ 2.10−21 M.s−1. To obtain this result, we combined: 1) the darkest environment possible, 2) an integrating sphere with extreme reflectivity which brings the maximum amount of photons onto the detector, 3) an amplified camera in binary mode (visible : 400 − 900) and a statistical model which optimizes detectivity, and 4) a semi-automatic procedure to operate in darkness. This setup enables the following: 1) the detection limit is ≈ 9.2 photons s−1cm−2 on the camera, which accounts for ≈ 1% of its dark current, 2) ≈ 12% of the photons emitted isotropically by the sample are detected, 3) measurement of light intensity variations is optimized by maximizing the detectivity, rather than by maximiz- ing the signal-to-noise ratio.Then, we studied the luminescence produced by the disproportionation of H2O2 in water. This reaction catalysed in cells by peroxidases, is important for the metabolism, and is critical to the understanding chemiluminescence in general and and luminol-based applications in particular. We quantified for the first time without a catalyst, the dose-dependent luminescence of the disproportionation reaction in pure water, with ≈ 15photonss−1cm−3 for [H2O2 = 90] mM. Using a well-known biological model, Saccharomyces cerevisiae (baker’s yeast), cultured in liquid, we showed a peak in the luminescence associated with the beginning of the exponential growth phase, followed by a sustained decrease over 10 hours. This light production represents approximately 10−5 photons per second per cell.We hope our work leads to better quantitative study of the ultra-weak luminescence in chemistry and biology. This quantification is necessary for understanding the fundamental underlying mechanisms behind luminescence and to develop chemical and biomedical applications
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Baffou, Guillaume. "Luminescence induite par microscopie à effet tunnel et étude des propriétés électroniques, chimiques et optiques de la surface de carbure de silicium 6H-SiC(0001)3x3." Phd thesis, Université Paris Sud - Paris XI, 2007. http://tel.archives-ouvertes.fr/tel-00190955.
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Le microscope à effet tunnel (STM) permet une analyse spatiale et spectroscopique de surfaces à l'échelle atomique. Mise en évidence peu après l'invention du STM, la lumière émise par la jonction tunnel contient des informations pertinentes sur les propriétés électroniques et optiques de surfaces ou de nano-objets.<br /><br />La thématique dans laquelle s'inscrit cette thèse est la luminescence induite par STM sur substrat semiconducteur à large bande interdite. Les travaux ont porté sur la reconstruction de surface SiC(0001)3x3 du carbure de silicium (SiC) et s'articulent autour de trois parties.<br /><br />La première partie est consacrée à l'étude de la luminescence de la jonction tunnel métal/vide/SiC(0001)3x3. Cette étude, en parallèle à des mesures de spectroscopie tunnel, a mis en évidence les mécanismes et propriétés de transport électronique le long des états de surface du SiC.<br /><br />Une deuxième partie est dédiée à l'adsorption de molécules organiques sur la surface SiC(0001)3x3. La fonctionnalisation organique du SiC est une étape indispensable pour l'étude de molécules individuelles mais aussi pour la conception de matériaux hybrides organique/inorganique. La résolution submoléculaire du STM associée à des calculs ab initio en collaboration ont dégagé un modèle de chimisorption détaillé de la phthalocyanine hydrogénée.<br /><br />La dernière partie décrit des simulations numériques, basées sur le formalisme des tenseurs de Green, de la lumière émise par la jonction tunnel. Ces travaux ont permis de modéliser d'une part l'influence de la forme de la pointe du STM sur le spectre de la lumière émise, d'autre part l'inhibition de la fluorescence de molécules individuelles excitées par STM.
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LIBRANTZ, ANDRE F. H. "Estudo comparativo da emissoes do Nd(3+) nas configuracoes 4fsup(2)5d e 4fsup(3) induzidas pela excitacao multifotonica em cristais de YLF, GLF, LLF." reponame:Repositório Institucional do IPEN, 2000. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10830.
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Butler, Sween J. "Nonlinear Light Generation from Optical Cavities and Antennae." Thesis, University of North Texas, 2017. https://digital.library.unt.edu/ark:/67531/metadc984232/.
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Semiconductor based micro- and nano-structures grown in a systematic and controlled way using selective area growth are emerging as a promising route toward devices for integrated optical circuitry in optoelectronics and photonics field. This dissertation focuses on the experimental investigation of the nonlinear optical effects in selectively grown gallium nitride micro-pyramids that act as optical cavities, zinc oxide submicron rods and indium gallium nitride multiple quantum well core shell submicron tubes on the apex of GaN micro pyramids that act as optical antennae. Localized spatial excitation of these low dimensional semiconductor structures was optimized for nonlinear optical light (NLO) generation due to second harmonic generation (SHG) and multi-photon luminescence (MPL). The evolution of both processes are mapped along the symmetric axis of the individual structures for multiple fundamental input frequencies of light. Effects such as cavity formation of generated light, electron-hole plasma generation and coherent emission are observed. The efficiency and tunability of the frequency conversion that can be achieved in the individual structures of various geometries are estimated. By controlling the local excitation cross-section within the structures along with modulation of optical excitation intensity, the nonlinear optical process generated in these structures can be manipulated to generate coherent light in the UV-Blue region via SHG process or green emission via MPL process. The results show that these unique structures hold the potential to convert red input pulsed light into blue output pulsed light which is highly directional.
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SIRONI, LAURA. "Nanoparticles for in-vitro and in-vivo biosensing and imaging." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2011. http://hdl.handle.net/10281/19278.
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In the last two decades several groups have investigated the changes of chemical and physical properties of materials with size in nanometric scales. These studies have highlighted a number of possible applications for nanostructures, which are now employed, for example, in biology and medicine for imaging, disease detection, diagnosis, sensing and therapy.
Noble metals (especially gold and silver nanoparticles) are particularly versatile for these applications due to the phenomenon known as surface plasmon resonance (SPR), an in-phase oscillations of all the conduction band electrons that resonates with the light wave electric field. The resonance frequency depends on the size, shape, orientation and dielectric constant of the nanoparticle. This coupling of SPR with the electromagnetic field leads to a large enhancement of all the nanoparticle radiative properties, such as absorption and scattering. The extinction cross section of these nanoparticles is 10^5-10^6 larger than that of organic dyes and in contrast to common molecular chromophores they are extremely photostable and, depending on the shape, they convert efficiently light into heat. The SPR, tunable in the visible (for spherical NPs) and near-infrared region (for anisotropic Nps) of the electromagnetic spectrum, can also interact, for gold nanoparticles a few nanometers in size, with the fluorescence emission of dyes and substantially modify their brightness and excited-state lifetime. Depending on the fluorophores-NP distance and the NPs anisotropy one can obtain fluorescence enhancement or quenching. In both cases we expect that any change in the dielectric constant of the NP surface, induced, for example, by a biorecognition process that occurs on the surface itself, can produce a change in the emission properties of the fluorophores.
SPR effect becomes also particularly important when combined with two-photon excitation (TPE), which consists in the simultaneous absorption of two photons, each carrying about half the energy necessary to excite the molecule. TPE offers a series of unique features for biological investigation both in vitro and in vivo. First, the two-photon absorption bands of the dyes commonly used in biological studies are wider than their one-photon analogous allowing the simultaneous excitation of multiple fluorophores with a single excitation wavelength. Second, the stimulating light beam has a high penetration depth because of the long infrared wavelengths used, allowing experiments in turbid media. Third, excitation takes place only at the plane of focus, due to the scaling of the probability of simultaneous photon absorption with the square of the light intensity. As a consequence TPE avoids the simultaneous absorption of photons outside the specimen drastically reducing both photo-toxicity and fluorophore bleaching. These advantages make nowadays TPE a well established tool for scientific biological and medical research and can be coupled to anisotropic gold nanoparticles.
In fact, the luminescence (TPL) induced by TPE is enhanced (when coupled with an appropriate plasmon resonance) by many orders of magnitude in non spherically symmetric NPs of noble metal with respect to the single photon excitation on smooth noble metal surfaces. These properties promise to improve the usefulness of these nanoparticles for in-vivo imaging in the NIR region of the electromagnetic spectrum. According to these considerations we have developed our project on two lines related to the use of gold nanoparticles for sensing and non linear imaging. The aim of the first part of this research project is to exploit changes of the dye excited-state lifetime and brightness induced by its interaction with the gold surface plasmons for detection of tiny amounts of protein in solution under physiological conditions. The system we investigated is based on 10 and 5 nm diameter gold NPs coupled (via a biotin- streptavidin linker) to the FITC dye and to a specific protein antibody. The interaction of the fluorophore with the gold surface plasmon resonances, mainly occurring through quenching, affects the excited state lifetime that is measured by fluorescence burst analysis in highly diluted suspensions. The binding of protein to the gold NPs through antigen-antibody recognition further modifies the dye excited-state lifetime, which change can then be used to measure the protein concentration. In particular, we have tested the nanodevice measuring the change of the fluorophore excited-state lifetime after the binding of the model protein bovine serum albumin (BSA); then we have applied the nanoassay in order to recognize the p53 protein, whose detection in the body is highly valuable as marker for early cancer diagnosis and prognosis, both in standard solutions and in total cell extracts. The selectivity of the construct with respect other globular proteins has been also addressed. The data indicate that the FITC excited-state lifetime is a very sensitive parameter in order to detect tiny amounts of protein in solution with an estimated limit of detection of about 5 pM, mostly determined by the statistical accuracy of the lifetime measurement.
In the second part of the project we focused on the exploitation of anisotropic gold nanoparticles as probes in cellular imaging. We have then studied their photoluminescence (TPL) properties under two photon excitation. We have focused on gold nanorods that can easily be obtained by synthesis with the standard surfactant CTAB (cetyl trimethylammonium bromide). The synthesis of asymmetric branched gold nanoparticles, obtained using for the first time in the seed growth method approach a zwitterionic surfactant, laurylsulphobetaine (LSB), has been developed in collaboration with the University of Pavia (Prof. P.Pallavicini). We have shown that LSB concentration in the growth solution allows to control the dimension of the NPs and the SPR position, that can be tuned in the 700-1100 nm Near Infrared range. The samples have been analyzed with a number of structural techniques to obtain a complete characterization: absorption spectra in the UV-Visible region, TEM images of the suspensions, Fluorescence Correlation Spectroscopy (FCS) and Dynamic Light Scattering (DLS) experiments in suspensions. From these data we reached information on the nanoparticles shapes, dimensions and aggregation. In particular, three different populations have been found: nanospheres with diameter lower than 20 nm, nanostars characterized by large trapezoidal branches, and asymmetric branched nanoparticles with high aspect ratio (3-4). A full characterization of the NPs TPL was performed for imaging applications by employing two photon excitation (TPE). The dependence of the TPL intensity on the power, wavelength and polarization of the incident light intensity was studied and TPL was exploited to study the cellular uptake of the nanoparticles in different cell lines (macrophages and HEK cells).
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Khan, Amena Lutfa Tabenda. "Analysis of electron-phonon coupling from the luminescence of conjugated polymers." Thesis, University of Cambridge, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.615099.
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Sun, Yuxuan. "Setup for Micro Photo- and Electro-Luminescence of Optoelectronic Device Structures." Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-175708.
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Photoluminescence (PL) is an optical emission induced by photon absorption in a material where electrons are excited from the ground state to excited states, then relax to the lowest excited states and recombine radiatively. The PL emission provides vital information on bandgap energy, material purity and crystal quality. In this project, a PL characterization system, also capable of electroluminescence (EL) measurements, was designed and assem- bled to measure optoelectronic device structures with the capabilities of recording PL or EL spectra as well as micrometer-resolved PL or EL maps on device structures or active components. In order to realize the system with the above functions, an optical setup and a monochro- mator were used to achieve micrometer-range resolution and reasonable signal-to-noise ra- tio. A hardware control platform needed to be designed and assembled to control the precise movement of the sample stage and monochromator as well as for acquiring the signal. A PC-based control software were developed for fully automatic measurements . Furthermore, adequate alignment and calibration methods had to be developed to tune the optical path, monochromator and control program. The setup employs the basic ideas of confocal microscopy, with the parallel laser input focused on the sample surface with a spot diameter of 0.78 μm. A Czerny Turner diffraction grating based monochromator is used to measure PL emissions. A 532 nm laser diode and an InGaAs or Si detector are applied in the system for spectral range of detection of at least 850- 1600 nm, i.e. covering the important data and tele communication bands. The project builds on a platform containing EasyDrivers, an Anduino Uno micro-controller and a Labview based operation software, together working with an amplifier circuit for stepper motors actuation and signal acquisition. Finally, different quantum well samples were measured, showing that the wavelength accuracy and resolution as well as the program flexibility meet the specifications of the setup.
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Wilkins, Matthew. "Multi-Junction Solar Cells and Photovoltaic Power Converters: High-Efficiency Designs and Effects of Luminescent Coupling." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/36181.
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Multi-junction photovoltaic devices based on III-V semiconductors have applications in space power systems and terrestrial concentrating photovoltaics, as well as in power-over-fibre and optical power conversion systems. These devices have between two and twenty junctions arranged in tandem, connected in series with optically transparent tunnel diodes. In some cases, they may include as many as eight different materials, including ternary and quaternary alloys, and >100 epitaxial layers in total.
A general method for simulating performance of these devices using drift-diffusion based device simulation tools is reviewed. This includes discussion of the geometry, discretization, and physical equations to be solved. A set of material parameters for some important materials is listed, and solutions are shown for an example of a lattice-matched four-junction GaInP / (In)AlGaAs / InGaAsN(Sb) / Ge solar cell including a dilute nitride based p-i-n junction with ∼ 0.9 eV band gap.
A sample of this dilute nitride junction with a 650 nm absorber layer was grown by molecular beam epitaxy and was shown to have short-circuit current density of 15.1 mA/cm2, sufficient for use in the 4-junction structure, while transmitting sufficient light through to the bottom (germanium) junction. Open-circuit voltage was up to 0.186 V at 1-sun, increasing to 0.436 V under 1500 suns concentration.
The device simulation methodology was extended to include effects of luminescent coupling and photon recycling. These effects are included by adding a term to the electron and hole continuity equations, and the resulting coupled system of equations is solved. No external iterative loop is required, as has been the case in other efforts to model these effects. A five-junction photonic power converter (PPC) is simulated and it is shown that the quantum efficiency of the device is significantly broadened through luminescent coupling. There is a 350 mV reduction in simulated open-circuit voltage (70 mV per junction) if luminescent coupling is neglected. This work was later extended to a 12-junction PPC device, where the simulation predicts a wavelength sensitivity of -1.1%/nm in the absence of luminescent coupling; this is reduced to -0.4%/nm when luminescent coupling is included in the calculation. The latter result, and the overall shape of the simulated quantum efficiency curve agree closely with experimental measurements.
Finally, two specific applications of PPCs are demonstrated. The first is in a step-up DC-to-DC converter, where a linear regulator combined with a laser/PPC pair can convert a 3.3 V input (commonly available from a single lithium polymer battery cell) into 12 V. Unlike conventional switching boost converters, this ‘photonic boost converter’ is not a source of ripple. In testing, a >80 dB reduction in ripple was measured compared with an equivalent switching boost converter, limited only by input noise of the instrument.The second application is in a 60 kW, 650 V switching circuit such as might be found in a hybrid or electric vehicle drivetrain. These circuits need several isolated power supplies to power gate drivers for the IGBT or SiC MOSFET switching components. This isolation is commonly provided by a small transformer, which inherently has a parasitic capacitance between primary and secondary windings and creates a path for EMI currents to flow from the high-power components to the power supply and control circuitry. By using a laser/PPC pair to provide the needed isolation, this parasitic capacitance can be largely eliminated; a 20 dB reduction in EMI current reaching the control FPGA is demonstrated.
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Savel, Paul. "Absorption à deux photons et photochromisme de complexes de ruthénium : application au stockage optique de données." Thesis, Rennes 1, 2014. http://www.theses.fr/2014REN1S090/document.
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Le développement des nouvelles technologies, de l'informatique et d'internet ces dernières décennies s'est accompagné d'une demande croissante de supports de stockage de l'information. En particulier, le stockage optique de données. Les supports conventionnels (Cd-Rom, Blue-ray…), basés sur un stockage en surface du disque, ont atteint aujourd'hui leurs limites. Une nouvelle technologie en cours de développement, basée sur un stockage de données en trois dimensions, est une alternative prometteuse pour supplanter les supports conventionnels. Les matériaux doivent intégrer des entités aux propriétés photochromes (commutateur moléculaire) et d'absorption multi-photonique démontrées. Au cours de cette thèse, nous avons envisagé la synthèse de molécules fonctionnelles qui présenteraient ces deux caractéristiques. Dans un premier temps, nous nous sommes intéressés à la synthèse et à l'étude comparative de complexes homo et hétéroleptiques de ruthénium présentant une certaine potentialité pour l'absorption à deux photons. Nous avons montré que ces systèmes étaient très actifs et qu'ils permettaient d'accueillir une entité photochrome sans perte des propriétés bi-photoniques. Nous avons par la suite étudié les propriétés en photochromisme de complexes de ruthénium tris-bipyridine originaux comprenant un motif azobenzène. La complexation au métal bouleverse profondément le photochromisme de l'azobenzène avec des caractéristiques cinétiques notablement différentes de celles des ligands. Enfin, nous avons étudié les propriétés de complexes hybrides composés de ligands pour l'absorption à deux photons et d'autres pour le photochromisme, ces composés sont actifs dans ces deux domaines. Nous discutons finalement du potentiel du comportement optique de films composés de ces complexes. Nous avons procédé à des essais préliminaires de modulation du signal SHG sur ces films. Nous souhaitons optimiser toutes les composantes du processus afin de déterminer le potentiel de ces composés en stockage optique de données<br>The development of new technologies , computer and internet in recent decades has been accompanied by an increasing demand for media storage information. In particular , the optical data storage .Conventional media ( CD-ROM , Blu-ray ... ) based on a storage disk surface, have now reached their limits. A new technology being developed , based on a data storage in three dimensions, is a promising alternative to replace conventional materials. Materials must include entities for photochromic properties (molecular switch) and multi- photon absorption demonstrated. In this thesis , we considered the synthesis of functional molecules which present these two characteristics. As a first step , we are interested in the synthesis and comparative study of homo and heteroleptic ruthenium complex having a certain potential for two-photon absorption . We have shown that these systems were very active and they allowed to host a photochromic entity lossless bi- photonic properties. We then studied the properties of originals photochromic ruthenium tris- bipyridine containing an azobenzene motif. The metal complexing profoundly changes the photochromism of azobenzene with significantly different from those ligands kinetics . Finally, we studied the properties of hybrid complexes of ligands for the two-photon absorption and others to photochromism , these compounds are active in both areas. We finally discuss the potential of the optical behavior of compounds of these complex films. We conducted preliminary tests of the SHG signal modulation on these films. We want to maximize all components of the process to determine the potential of these compounds in optical data storage
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Suleimanov, Iurii. "Nano-objets et nano-composites à transition de spin basés sur des complexes du fer(II) avec des ligands 1,2,4-triazoles." Thesis, Toulouse 3, 2016. http://www.theses.fr/2016TOU30017.
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L'échelle moléculaire est de plus en plus considérée comme une solution alternative pour la miniaturisation des composants électroniques en vue de la construction de dispositifs fonctionnels. L'approche actuelle "top-down" basée sur la technologie du silicium force les chimistes du solide, les physiciens et les électroniciens à manipuler progressivement des quantités de matière de plus en plus faibles. Dans ce domaine, les dispositifs moléculaires offrent des perspectives remarquables avec des niveaux de sensibilité et de sélectivité qui ne peuvent pas être atteints avec les matériaux à semi-conducteurs conventionnels. Dans ce contexte, les complexes ou polymères de coordination représentent une classe importante de composés possédant des propriétés de commutation magnétiques, optiques et électrochimiques intéressantes. En particulier, les composés à transition de spin (transition intra-métallique de l'état haut spin vers l'état bas spin) des métaux de transition sont bien adaptés à cette stratégie car ils peuvent être le siège d'une transition réversible du premier ordre avec hystérésis sous l'effet d'une perturbation extérieure (température, pression ou éclairement) impliquant des modifications magnétique, optique et structurale. Dans ces travaux de thèse, des matériaux susceptibles de présenter des propriétés de bistabilité avec hystérésis autour de la température ambiante sont présentés et discutés. Un des objectifs est d'étudier l'évolution de leurs propriétés en fonction de la taille et de valoriser ces matériaux. Pour cela, ces composés ont été nano-structurés. Ainsi nous avons élaboré des nanoparticules à base de composé à transition de spin par différentes voies de synthèse et réalisé des films minces et des nanostructures de ces matériaux par des méthodes de lithographie douce et de lithographie électronique. Pour caractériser les propriétés de ces nouveaux objets, nous nous sommes orienté vers l'utilisation de nouvelles techniques de détection optiques et en particulier vers des techniques qui permettent la mesure de la variation du changement d'indice optique de ces matériaux, à savoir, des mesures de la variation des plasmons de surface lorsque des couches minces bistables de ces composés sont mises au contact de surface d'or et des mesures de variation de l'efficacité de diffraction à partir de réseaux de motifs de tailles micro- et nanométriques. Par ailleurs, une méthode basée sur la variation de l'intensité de fluorescence d'un fluorophore sélectionné et intégré au sein de composé mixte (composé à transition de spin - fluorophore) a également été développée. L'ensemble de ces méthodes concourt à pouvoir détecter un objet unique de taille nanométrique<br>The thesis is devoted to the preparation of new nanoobjects and nanocomposites of spin crossover complexes [Fe(Htrz)2(trz)](BF4) and [Fe(NH2-trz)3](NO3)2 (where Htrz - 1,2,4-triazole, trz - 1,2,4-trazolato, NH2-trz - 4-amino-1,2,4-triazole) and investigation their properties. Nanoobjects of mixed-ligand complexes with different ratio of 4-amino-1,2,4-triazole to 1,2,4-triazole were synthesized in reverse emulsions. It was shown that the increasing of the of 4-amino-1,2,4-triazole quantity leads to the increasing of nanoparticles anisotropy while spin crossover temperatures decrease. Double-step spin transition was observed at 20% mol of 4-amino-1,2,4-triazole, while at concentrations over 50% mol. spin crossover properties of [Fe(Htrz)2(trz)](BF4) completely disappear. Investigations of their morpholgy, size and spin transition characteristics as well as investigations of mechanisms of the fluorescent properties change under the spin switching process are shown. We consider obtaining nanoobjects of mixed-ligand complexes of iron (II) based on 1,2,4-triazole and 4-amino-1,2,4-triazole. The ligands ratio influences the morphology, size and characteristics of the spin transition of nanoobjects obtained. New modification of the complex [Fe(NH2-trz)3](NO3)2 in the form of nanoobjects was obtained using ligand excess. High transition temperature of this form was evidenced by various methods of analysis. This form was found to be isostructural with a resolved structure of [Fe(NH2-trz)3](NO3)2 · 2H2O. Series of nanocomposites with plasmonic and luminescent properties were prepares. For the core-shell composite with gold nanoparticles higher efficiency of the spin state switching due to the photothermal effect was demonstrated in comparison to the control sample. Fluorescent spin crossover composites with quantum dots, organic luminophors and terbium complexes were described. For all these composites the luminescence intensity variation as a function of temperature have been found. The mechanisms responsable of the luminescence intensity variation at two spin state are discussed. These mechanisms include resonant energy transfer, mechanical strain and photon reabsorption. High photostability fort he terbium - spin crossover composite is demonstrated comparing to previously obtained similar spin crossover luminescetnt composites. An example of a practical application of obtained composites for manufacturing fluorescent thermosensitive paper is shown
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Bellec, Matthieu. "Nanostructuration par laser femtoseconde dans un verre photo-luminescent." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2009. http://tel.archives-ouvertes.fr/tel-00459311.
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L'objet de cette thèse est l'étude de l'interaction d'un laser femtoseconde avec un support photosensible particulier : un verre phosphate dopé à l'argent appelé verre photo-luminescent (PL). Une nouvelle approche permettant de réaliser en trois dimensions dans un verre PL des nanostructures d'argent aux dimensions bien inférieures à la limite de diffraction est tout d'abord présentée. La mesure des propriétés optiques et structurales pour différentes échelles (spatiales et temporelles) a permis de proposer un mécanisme de formation des structures photo-induites qui est basé sur un jeu subtil entre les phénomènes d'absorption non-linéaire et de thermo-diffusion. La deuxième partie de cette thèse sera rientée sur les propriétés optiques (linéaires et non-linéaires) et les applications des ces nanostructures d'argent. En particulier, l'exaltation des propriétés non-linéaires des agrégats d'argent sera exploitée pour stocker optiquement de l'information en trois dimensions.
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Cantelli, Andrea <1988>. "Luminescent and Photo-Responsive Gold Nanoparticles for Bio-Applications." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amsdottorato.unibo.it/7616/1/cantelli_andrea_tesi.pdf.
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In thesis work it has been given an overview of the most recent advances in the synthesis, characterization and bio-medical application of luminescent Gold nanospecies. It has been shown that the combination of photoactuators and nanostructures results in an apparent reduction of dyes PI QYs, due to the nanomaterials absorbance contribution, also in absence of actual interactions between the two components. It has been proposed a simple approach to take into consideration this contribution and to perform quantitative measurements of dyes PI efficiencies variations in presence of nanoparticles. The PI QY reduction has been found to be qualitatively proportional to the magnitude of the interaction between the dye and the particles measured by NMR. It has been shown that strong interaction between the two components result in significant decreases of the dye PI QY. The photoisomerization effectively determines a change in the repartition of the AB derivative between particle monolayer and solution. This confirms that photoisomerization reaction can probably be exploited for light triggered drug release. These results provided valuable tools and methodologies which improved the state of the art in the quantitative study of light triggered processes in nanoparticles based systems.
For the first time it has been proven that GNPs luminescence can be switched on and off thanks to the photoisomerization of an azobenzene derivative covalently bound on the Gold surface. This has been proven to happen thanks to an efficient energy transfer between the trans AB derivative and the GNPs which leads to a sensitized NIR emission whose intensity can be tuned by photoisomerization. These unprecedented results are promising for the development of Gold based light responsive nanoparticles for theranostics.
Finally, starting from Au25(Cys)18, it has been successfully developed a complex probe for luminescence based imaging composed by NIR emitting GNCs encapsulated inside mesoporous PEGylated silica NPs.
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Cantelli, Andrea <1988>. "Luminescent and Photo-Responsive Gold Nanoparticles for Bio-Applications." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amsdottorato.unibo.it/7616/.
Full textAbstract:
In thesis work it has been given an overview of the most recent advances in the synthesis, characterization and bio-medical application of luminescent Gold nanospecies. It has been shown that the combination of photoactuators and nanostructures results in an apparent reduction of dyes PI QYs, due to the nanomaterials absorbance contribution, also in absence of actual interactions between the two components. It has been proposed a simple approach to take into consideration this contribution and to perform quantitative measurements of dyes PI efficiencies variations in presence of nanoparticles. The PI QY reduction has been found to be qualitatively proportional to the magnitude of the interaction between the dye and the particles measured by NMR. It has been shown that strong interaction between the two components result in significant decreases of the dye PI QY. The photoisomerization effectively determines a change in the repartition of the AB derivative between particle monolayer and solution. This confirms that photoisomerization reaction can probably be exploited for light triggered drug release. These results provided valuable tools and methodologies which improved the state of the art in the quantitative study of light triggered processes in nanoparticles based systems.
For the first time it has been proven that GNPs luminescence can be switched on and off thanks to the photoisomerization of an azobenzene derivative covalently bound on the Gold surface. This has been proven to happen thanks to an efficient energy transfer between the trans AB derivative and the GNPs which leads to a sensitized NIR emission whose intensity can be tuned by photoisomerization. These unprecedented results are promising for the development of Gold based light responsive nanoparticles for theranostics.
Finally, starting from Au25(Cys)18, it has been successfully developed a complex probe for luminescence based imaging composed by NIR emitting GNCs encapsulated inside mesoporous PEGylated silica NPs.
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Gloukhov, Roman. "Cinétique des excitations électroniques dans les cristaux inorganiques isolants." Lyon 1, 1999. http://www.theses.fr/1999LYO10213.
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Ce travail a ete consacre a l'etude de la transformation et du transfert de l'energie de particules ionisantes rapides ou de photons de haute energie dans les solides. La relaxation de l'energie peut etre decrite en considerant trois etapes. La premiere est relative a la multiplication des excitations electroniques (ee). Durant la deuxieme etape, les excitations electroniques se thermalisent due a l'emission de phonons. Dans l'etape finale se produisent la migration et la recombinaison des excitations electroniques. Ce dernier stade s'accompagne souvent d'une emission de luminescence. On a etudie les differents aspects de transformation de l'energie durant ces trois etapes. Les principaux resultats sont resumes ci-apres. La technique de modelisation de la relaxation des ee dans les solides a ete developpee. On a etabli que le nombre moyen d'excitations electroniques depend fortement des proprietes dielectriques (de la structure electronique) du solide. Pour les cristaux ayant une structure electronique complexe (comme cef3 et baf2), l'energie moyenne pour la creation d'une excitation electronique pouvant conduire a la luminescence rapide, est 2-3 fois plus grande que celle necessaire a la creation d'une paire electron-trou. On a etudie le probleme de la thermalisation des particules dont les energies sont inferieures au seuil de multiplication des excitations electroniques. On a procede a une etude de la migration des electrons et des trous separes. On a trouve que la variation du rendement quantique de luminescence en fonction du coefficient d'absorption devie du modele traditionnel dit excitonique. On a propose un modele de transfert de l'energie dans la trace creee dans le solide par une particule de tres haute energie. Le rendement et la cinetique de la luminescence creee par l'interaction d'une particule (electron, mesons, proton, particule alpha) de tres haute energie avec un cristal cross-luminescent ont ete calcules. On a pu expliquer l'influence du type de rayonnement ionisant sur les proprietes de cross-luminescence. On a etudie l'influence des correlations spatiales des excitations electroniques sur le rendement quantique et sur la cinetique de la fluorescence, sur un exemple de cross-luminescence dans baf2, apres absorption d'un photon de haute energie. La simulation de la relaxation de l'energie par la methode de monte-carlo a montre que la region excitee creee dans ces conditions, possede une structure complexe. Il existe en particulier des regions de haute densite d'excitations ou des ee peuvent se recombiner non-radiativement. Cela explique l'extinction de cross-luminescence qui a ete observee experimentalement.
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Bouazaoui, Mohamed. "Spectroscopie laser à deux photons d'ions de terres rares en milieu cristallin." Lyon 1, 1990. http://www.theses.fr/1990LYO10242.
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Ce travail est consacre a l'etude du processus d'absorption a deux photons dans des ions de terres rares incorpores dans des matrices cristallines. De nouvelles transitions a deux photons ont ete observees et analysees theoriquement pour les ions eu3+ et gd3+. De plus, la variation des intensites de transitions en fonction de la polarisation a ete reproduite de maniere satisfaisante dans le cadre d'une analyse theorique comportant les termes du second ordre et du troisieme ordre de l'amplitude de probabilite d'une transition a n photons
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Zheng, Zheng. "Development of Far-Red / Near-Infrared Luminescent Chromophores and Nanoparticles for in vivo Biphotonic Applications." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEN024/document.
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Développer de nouveaux fluorophores ayant une forte section efficace d’absorption à deux photons (ADP) et des propriétés d'émission dans le rouge lointain est important, en particulier pour l’imagerie in-vivo profonde. Cette gamme de longueur d'onde correspond en effet à la fenêtre de transparence optique des tissus. Cette thèse étudie le potentiel de nouveaux fluorophores émettant dans rouge construits sur un noyau fluorène pour la microscopie à deux photons in-vivo, en privilégiant l'imagerie du système vasculaire, d'une part, et la mesure optique de la pression d'oxygène dissous, d'autre part.Ainsi, une famille de chromophores asymétriques a été conçue et synthétisée. La plupart des chromophores présentent une forte émission dans le proche IR, induite par l'agrégation. De plus, une stratégie de co-protection basée sur un système micellaire / silice a été utilisé pour préparer des nanoparticules avec un intérieur apolaire et conserver les propriétés optiques des chromophores dipolaires en solution aqueuse. Des mesures de fluorescence excitée à deux photons ont été menées en solvant organique et en suspension aqueuse. Les agrégats et les nanoparticules ont été utilisés avec succès en imagerie biphotonique du système vasculaire sur petit animal en utilisant un modèle de tumeur à l'intérieur de la peau de l'oreille de la souris. Les nanoparticules de silice montrent une coloration exceptionnelle du système vasculaire qui en fait de parfaits marqueurs du système vasculaire.Dans un deuxième temps, quatre nouveaux chromophores, absorbant à deux photons, ont été synthétisés et leurs propriétés photo physiques à un et à deux photons ont été étudiées. Le chromophore le plus adapté a ensuite été greffé de manière covalente par chimie click, à un complexe de palladium avec un ligand porphyrine, cœur phosphorescent dont l’émission est sensible à la présence d’oxygène. Deux composés contenant quatre ou huit absorbeur à deux photons ont été obtenus et étudiés. Les résultats démontrent que l'incorporation d'un chromophore ADP approprié peut effectivement augmenter les propriétés d’ADP du système, ce qui permet une sensibilité efficace vis-à-vis de l'oxygène<br>The development of fluorophores with efficient two-photon absorption (TPA) and emission properties in the far red/NIR is important, especially for in depth in-vivo optical imaging as this wavelength range corresponds to the optical transparency window of tissues. This thesis investigates the potential of new red emitting fluorophores containing a fluorene ring for in-vivo two-photon microscopy focusing on vascular imaging on one hand and on oxygen pressure measurement on the other hand.A new series of asymmetrical fluorene-based chromophores were designed and synthesized. Their structure-property relationships were systematically investigated. It was found that most of chromophores exhibit aggregation-induced emission behaviors in the NIR region. In addition, a micelle/silica coprotection strategy was proposed to prepare nanoparticles with a less polar interior, which can be used to conserve optical properties of dipole chromophores in aqueous solution. The two-photon excited fluorescence (TPEF) measurements indicate that they all display obvious TPA activities in organic solvent and aqueous suspension. Both the NIR-emissive aggregates and nanoparticles have been successfully used for TPEF imaging of blood vessels inside mouse ear skin. The silica nanoparticles show outstanding staining of the vascular system making them perfect blood pool markers.On a second part, four new fluorene-based two-photon absorbing chromophores have been synthesized and their one- and two-photon photophysical properties were investigated. The optimum chromophore was successfully attached covalently to an oxygen responsive phosphorescent Pd-porphyrin complex by click chemistry. Two new compounds contain four or eight TPA chromophores donor connected to the phosphorescent core. The result demonstrate that the incorporation of a suitable TPA chromophore can effectively enhance the TPA of the system, allowing efficient sensitivity towards oxygen
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Jacquet, Margot. "Complexes de ruthénium (II) intégrant l'unité photochromique Diméthyldihydropyrène : Vers de nouvelles photo-réactivités." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAV088/document.
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Le travail présenté dans ce mémoire est dédié à l'élaboration de complexes de ruthénium(II) photo-commutables originaux incorporant le couple photochrome Diméthyldihydropyrène (DHP) / Cyclophanediène (CPD), pour de futurs dispositifs moléculaires optoélectroniques.Dans le but de réaliser des systèmes complexes pouvant reproduire les fonctions d'un circuit logique, une stratégie intéressante repose sur l'association de molécules photo-commutables et de complexes métalliques. Cependant, cette stratégie se confronte à certains obstacles majeurs, généralement associés à la perte des propriétés de commutation des photochromes organiques. En réponse aux précédents résultats confirmant cette tendance, deux nouvelles familles de complexes terpyridiniques de ruthénium(II) à base de DHP ont été synthétisées. Sachant que la présence de fonction pyridinium améliore significativement les propriétés d'isomérisation du cœur DHP, les centres métalliques ont été connectés soit via un lien benzyle pyridinium (Ru-Lpy+tpy) soit via un lien aryle pyridinium (Ru-LZincke). Bien que fonctionnant à plus faible énergie, le complexe Ru-LZincke présente des performances amoindries, en revanche les complexes Ru-Lpy+tpy affichent une préservation notable de leurs propriétés de commutation. Suite à la découverte d'une photo-réactivité originale favorisée par la présence du centre métallique, une famille analogue à base de complexes bipyridiniques de ruthénium(II) (Ru-Lpy+bpy) a été étudiée. Même si les mécanismes ne sont pas complètement rationalisés, les complexes Ru-Lpy+bpy se sont révélés être de remarquables candidats pour la réalisation de photo-commutateurs réversibles quantitativement dans le domaine du visible<br>The work of this thesis is devoted to the development of original photo-switchable ruthenium(II) complexes incorporating the photochromic Dimethyldihydropyrene (DHP) / Cyclophanediene (CPD), for future optoelectronic molecular devices.In order to realize complex systems capable of reproducing the functions of a logic circuit, an interesting strategy is based on the association of photo-switchable molecules and metal complexes. However, this strategy is confronted with some major obstacles, generally associated with the loss of the switching properties of organic photochromes. In response to previous results confirming this trend, two new families of DHP-based terpyridine ruthenium(II) complexes have been synthesized. Since the presence of pyridinium function significantly improves the isomerization properties of the DHP core, the metal centers were connected either via a pyridinium benzyl linkage (Ru-Lpy+tpy) or via an aryl pyridinium linkage (Ru-LZincke). Although operating at lower energy, Ru-LZincke complex exhibits lessened performance, whereas Ru-Lpy+tpy complexes exhibit a notable preservation of their switching properties. Following the discovery of an original photo-reactivity favored by the presence of metal center, an analogue family based on ruthenium (II) bipyridine complexes (Ru-Lpy+bpy) was studied. Even if the mechanisms are not completely rationalized, Ru-Lpy+bpy complexes have proved to be remarkable candidates for the realization of quantitatively reversible photo-switches in the visible domain
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Bizarri, Grégory. "Étude des mécanismes de dégradation du luminophore Ba Mg Al10 O17 : Eu 2+ : influence des traitements thermiques et de l'excitation par des photos de haute énergie (ultra violet du vide)." Lyon 1, 2003. http://www.theses.fr/2003LYO10241.
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Parmi les technologies d'avenir dans le domaine de l'affichage, celle des panneaux à plasma exige l'amélioration des performances des matériaux luminophores. L'objectif de cette thèse est de comprendre les mécanismes responsables des performances des luminophores ainsi que ceux à l'origine d'effets limitants comme le vieillissement. L'étude porte sur le luminophore Ba Mg Al10 O17 : Eu 2+, la composante bleue qui est la plus sensible au vieillissement. Cette étude montre que le vieillissement est dû à la dégradation consécutive aux recuits que subissent les luminophores lors de la fabrication des panneaux et aux mécanismes d'altération photochimique induits par l'exposition au rayonnement ultra violet du vide produit par le plasma. La baisse des performances liée aux recuits est essentiellement due à l'oxydation du dopant. Dans le cas de l'excitation VUV, nos travaux, grâce à des mesures de spectroscopie VUV et de thermoluniescence, ont permis de mettre en évidence le rôle primordial joué par les pièges
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Dubrovin, V. D., A. I. Ignatiev, N. V. Nikonorov, and A. I. Sidorov. "Influence of Halides on the Luminescence of Silver Molecular Clusters in Photo-Thermo-Refractive Glasses." Thesis, Sumy State University, 2013. http://essuir.sumdu.edu.ua/handle/123456789/35248.
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The luminescence spectra of silver molecular clusters in photo-thermo-refractive glasses are investigated in detail before and after the UV irradiation and also after the heat treatment of the samples. Also investigat-ed are (I) the influence of halogens such as Cl and Br in glass matrix composition on the luminescence of sil-ver molecular clusters in photo-thermo-refractive glasses and (II) the effect of temperature on the lumines-cence spectra and the integrated intensity of luminescence of photo-thermo-refractive glasses.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35248
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Gu, Minming. "Cartographie d'émission de photons en microscopie par effet tunnel : application à la luminescence locale du silicium poreux." Aix-Marseille 2, 1993. http://www.theses.fr/1993AIX22047.
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En placant un detecteur photonique au voisinage de la jonction pointe-echantillon d'un microscope par effet tunnel (stm), nous avons pu mesurer les proprietes optiques locales des surfaces en utilisant a la fois le stm et l'emission radiative associee. Nous avons etudie sous ultra-vide la cartographie d'emission de photons, les variations de l'intensite lumineuse en fonction de la tension pointe-echantillon ainsi que la spectroscopie optique d'un film d'ag/si(111)77, de composes semiconducteurs et surtout du silicium poreux luminescent. Pour le film ag/si(111)77, on observe un maximum d'emission a 3,5 volts, ainsi qu'une etroite correlation entre la topographie et l'emission lumineuse. Ce phenomene optique est attribue aux modes de plasmons locaux induits par la proximite de la pointe. Pour les composes semiconducteurs (zno, cds, gase, tio#2. . . ), la radiation relative a la bande interdite et l'emission due aux impuretes sont revelees dans les spectres optiques. La cartographie d'emission de photons obtenue simultanement avec la topographie montre un contraste a l'echelle nanometrique qui est attribue aux defauts pres de la surface. Pour le silicium poreux luminescent, la topographie et le profil d'intensite lumineuse sont caracterises a l'echelle nanometrique. Ces resultats etayent les modeles theoriques reposant sur des effets de confinement quantique. De plus, le spectre de cathodoluminescence a basse energie montre que les photons sont emis dans le visible entre 500 et 800 nm
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Longaresi, Rafael Henriques. "Estudo da anisotropia de emissão luminescente de filmes poliméricos ordenados." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/88/88131/tde-21012013-145713/.
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Processos fotofísicos em polímeros conjugados estão intimamente relacionados com a conformação dos segmentos moleculares. Filmes finos de polímeros conjugados apresentam uma anisotropia intrínseca resultante da conformação dos segmentos moleculares tornando esses materiais atrativos em estudos fotofísicos pela emissão polarizada apresentada quando excitado via radiação eletromagnética ou sob aplicação de uma diferença de potencial elétrico. Neste trabalho procuramos correlacionar o espectro de emissão fotoluminescente de filmes finos de um derivado do polifluoreno, nominalmente poli(9,9-dioctilfluorenil-2-7-diil) terminado com dimetilfenil, com sua anisotropia molecular. Filmes finos mecanicamente estirados sofrem um processo de reordenamento molecular induzindo a emissão de luz polarizada predominantemente na direção de estiramento. O estiramento ocasiona ainda um aumento no comprimento de conjugação efetivo dos segmentos moleculares influenciando no acoplamento elétron-fônon. Através da técnica de elipsometria, foi possível determinar os estados de polarização da luz (através dos parâmetros de Stokes) e medidas de fotoluminescência estacionária dependente da temperatura nos possibilitou aferirmos sobre o acoplamento elétron-fônon a partir do Princípio de Franck-Condon. Medidas de fotoluminescência de excitação (PLE) determinou que o espectro da PL consiste da sobreposição espectral de duas espécies emissoras: a espécie isolada e a espécie agregada. Para baixas temperaturas a PL apresenta picos de emissão bem definidos como resultado da dinâmica molecular do PFO correspondendo ao favorecimento de emissão da espécie isolada. Para temperaturas acima da temperatura de transição \'beta\' (~270 K), a emissão da espécie agregada é favorecida, ocorrendo uma possível transferência de energia da espécie isolada para a agregada. O estiramento induz um aumento do comprimento de conjugação, refletido na diminuição do fator de Huang-Rhys, \'S IND. ISO\'POT. LO\'|140 K = 0,40 para amostra não estirada e \'S IND. ISO\'POT.2LO\'| 140 K = 0,19 para a amostra com a maior taxa de estiramento, tornando o espectro mais resolvido. Amostras não estiradas sob excitação paralela ao estiramento apresentaram polarização total de emissão P = 3,4% linearmente paralela ao estiramento e anisotropia de fluorescência de r = 0,025 e amostras com estiramento L = 2Lo apresentaram P = 46,1% de emissão polarizada ao longo da direção de estiramento e uma anisotropia de fluorescência de r = 0,27. A emissão polarizada mostrou ser independente da temperatura. A anisotropia de fluorescência mostrou ser fortemente dependente do estiramento e da anisotropia para temperaturas acima de 340 K, temperatura característica de um inicio de transição de fase do PFO.<br>Photophysics processes in conjugated polymer are closely related with the molecular segments conformation. Conjugated polymers thin films has shown an intrinsic anisotropy due to the molecular segments conformation making this materials attractive in photophysics studies by its polarized emission when stimulated by light or biased. In this work, we correlated the photoluminescence spectra of a derivative PFO polymer thin films, namely poly(9,9-dioctylfluorenyl-2,7-diyl) end capped with dimethylphenyl, with the molecular anisotropy. Mechanically stretched thin films undergo a molecular rearrangement process of inducing emission of light predominantly polarized in the direction of stretch. The stretching also causes an increase in the effective conjugation length of the molecular segments influencing the electron-phonon coupling. By ellipsometry technique, it was possible to determine the polarization states of light (by the Stokes parameters) and temperature dependent stationary photoluminescence measurements enabled us to get the electron-phonon coupling from the Franck-Condon principle. Measurements of photoluminescence excitation (PLE) have determined that the PL spectrum consists of spectral overlap of the two emitting species: the isolated and aggregated species. At low temperatures the PL emission peaks has presented well-defined as a result of PFO molecular dynamics favoring the emission of the isolated species. For temperatures above the transition beta temperature (270 K), the emission of aggregated species is favored, causing a possible energy transfer isolated to aggregate species. The stretching induces an increase in the conjugation length, reflected in the decreasing Huang-Rhys factor \'S IND. ISO\' POT. LO\'|140 K = 0,40 to non-stretched samples and \'S IND. ISO\' POT. 2Lo\'| 140 K = 0,19 for the sample with the highest draw ratio, making the spectrum more resolved. Unstretched samples under polarized excitation parallel to the stretching showed total polarized emission P = 3,4% linearly parallel to the stretching and fluorescence anisotropy of r = 0,025 and the L = 2Lo samples showed P = 46,1% of polarized emission along the direction of stretching and fluorescence anisotropy r = 0,27. The polarized emission was found to be independent of temperature. The fluorescence anisotropy was found to be strongly dependent of stretching rates and for temperatures above 340 K, a characteristic onset temperature of phase transition of the PFO.
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Molinaro, Céline. "Etude par luminescence à deux photons des propriétés plasmoniques de nano-objets uniques métalliques ou hybrides." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS321/document.
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Ma thèse a été centrée sur l’étude par luminescence à deux photons (TPL) de nanostructures d’or uniques, éventuellement couplées, dans le but d’en déterminer les propriétés de nano-antennes optiques. Les différentes expériences réalisées ont permis de mettre en évidence les paramètres clés à l’origine de la luminescence à deux photons (TPL) permettant de mettre en évidence le rôle du plasmon transverse. Ce résultat a été confirmé par l’étude de nanobipyramides présentant des caractéristiques plasmoniques légèrement différentes. Ce modèle a été approfondi via l’étude des propriétés TPL de nanobâtonnets présentant des volumes différents mais des résonances plasmoniques identiques. Enfin, en confrontant les résultats expérimentaux à des simulations obtenues par BEM (Boundary Element Method), nous avons montré que le signal provenait a priori des atomes du volume de la NP. Des problèmes de photo-dégradations ont par ailleurs été constatés et analysés. Au-delà des nano-bâtonnets, nous avons quantifié les effets dits de pointes de nanobipyramides présentant des caractéristiques plasmoniques proches de celles des bâtonnets. Nous avons également pu mettre en évidence de très fortes intensités TPL sur les points chauds issus d’échantillons d’or semi-continu. Un second volet de mes travaux a concerné la mise en œuvre et la caractérisation des propriétés optiques linéaires et non-linéaires de nano-émetteurs hybrides individuels couplant une nano-antenne à des fluorophores. Différentes techniques ont été testées : la mise en œuvre de dépôts multicouches (méthode dite « layer-by-layer »), ou la nanophotopolymérisation localisée. Dans les deux cas, outre la complexité de mise en œuvre de ces techniques, nous avons été confrontés à la difficulté d’extraire le signal des molécules du très fort signal de luminescence à deux photons des nanostructures d’or<br>My PhD work has been dealing with the two-photon luminescence (TPL) study of single gold nanostructures, possibly coupled in order to determine their nano-antenna optical properties. Key parameters to explain the origin of the TPL were provided from the two-photon luminescence study of single small 10 nm x 40 nm colloidal gold nanorods (GNR) which highlight the transverse plasmon influence. This origin was confirmed by the results obtained after the characterization of nanobipyramid exhibiting plasmonic properties closed to nanorods. A deeper insight in this model was further developed after investigating the properties of gold nanorods having closed aspect ratio and plasmonic resonances but increasing volume. Experimental data were correlated with BEM (Boundary Elements Method) simulations. It was shown that the TPL signal was coming from the bulk atoms. Photodegradations problems have moreover been observed and analyzed. Above the analysis of gold nanorods, the lightning rod effect of nanobipyramid was also investigated. Finally very high TPL intensity spots were recorded in semi-continuous gold films close to percolation. A second part of my study was related to the fabrication and the characterization of the optical properties of hybrid nano-emitters. They were fabricated by coupling a nano-antenna with fluorophores. Two different techniques were tested: the so-called layer-by-layer method and localized nanophotopolymerization. In both cases, together with the difficulty to accurately control both methods, retrieving the molecules signal from the huge TPL signal of the gold nanostructures was shown to be rather difficult
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Guénaud, Charles. "Etudes des propriétés optiques de semiconducteurs à grand gap : puits ZnSe/ZnCdSe et couches minces de GaN." Paris 6, 1999. http://www.theses.fr/1999PA066224.
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Grund, Olof. "Modification of a transient EPR and photoluminescence detection setup." Thesis, Uppsala universitet, Institutionen för fysik och astronomi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-328896.
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Climate change has given rise to higher demand of renewable energy. Conventional non-organic solar cells are still seen the most on the market but the last 10-20 years there has been an exponential increase in research about organic solar cells. The research demands measurements done on increasing fast time scales as insights about the topic and technology develops. Here is presented configurations done at the Isaak spectrometer at Freie Universit\"{a}t Berlin. The spectrometer is used for studying charge transport in organic solar cells as well as hybrid solar cells made from organic and inorganic semiconductors. One important feature for the time response is the Q factor property of the resonator in which the sample is placed. The Q factor describes the rate of energy loss relative to the stored energy of the resonator. The Q factor dependency over different temperature was studied in order to gain vital knowledge about the time response of the setup. Further new equipment was been installed at the setup and programmed in FSC2. This in order to increase the sensitivity of the optical setup, secure the personnel from possible dangerous excitation laser and in order to do more automated measurements. As the optical path was modified by installing a new optical fiber a new calibration had to be done. Finally, in order to try the functionality of the new equipment an automated energy dependency measurement was done on the polymer MEH-PPV and the polymer:fullerene blend MEH-PPV:PCBM. The automatic process of measuring was successful.
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McGarvey, D. J. "Photo-processes of tetrapyrrolic sensitisers studied laser flash photolysis, pulse radiolysis and singlet oxygen luminescence techniques." Thesis, Open University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233555.
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Gutmann, Johannes [Verfasser], and Hans [Akademischer Betreuer] Zappe. "Photonic luminescent solar concentrators : : how photonic crystals affect the emission and guiding of light = Photonische Fluoreszenzkonzentratoren." Freiburg : Universität, 2014. http://d-nb.info/1123484880/34.
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Delcey, Nicolas. "Tectonique moléculaire : réseaux moléculaires à propriétés optiques assemblées par des liaisons hydrogène chargées." Phd thesis, Université de Strasbourg, 2012. http://tel.archives-ouvertes.fr/tel-00832512.
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La conception et la préparation de réseaux moléculaires organiques et hybrides à l'état cristallin ont été envisagées par un processus itératif d'auto-assemblage entre des briques de construction moléculaires préprogrammées et complémentaires appelées tectons. Cette approche est basée sur la reconnaissance moléculaire de modules dicationiques, donneurs de liaisons hydrogène, et d'unités anioniques, accepteurs de liaisons hydrogène. Ainsi, la combinaison des tectons moléculaires de la famille des bis-benzimidazoliums, intrinsèquement luminescents, avec des anions polycyanométallates conduit à la formation de réseaux moléculaires hybrides luminescents à l'état cristallin. Il a été procédé à l'étude des propriétés photophysiques de ces réseaux à l'état solide. De même, l'association de bis-amidiniums,briques dicationiques, à des anions de type azodibenzoates mène à des assemblages cristallins possédant la propriété de photo-commutation, c'est-à-dire conduisant à une isomérisation sous stimulus lumineux.
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Banaei, Esmaeil. "Polymer Optical Fibers for Luminescent Solar Concentration." Doctoral diss., University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5898.
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Luminescent solar concentrators (LSC's) are promising candidates for reducing the cost of solar power generation. Conventional LSC's are slab waveguides coated or doped with luminescence materials for absorption and guiding of light to the slab edges in order to convert optical energy into electricity via attached photovoltaic (PV) cells. Exploiting the advantages of optical fiber production, a fiber LSC (FLSC) is presented in this thesis, in which the waveguide is a polymeric optical fiber. A hybrid fiber structure is proposed for an efficient two-stage concentration of incident light, first into a small doped core using a cylindrical micro-lens that extends along the fiber, and second to the fiber ends by guiding the fluoresced light from the active dopants. Flexible sheets are assembled with fibers that can be bundled and attached to small-area PV cells. Small dimensions and directional guiding of the fibers allow for approximately one order of magnitude geometrical gain improvement over that of existing flat LSC's. In addition, the undesired limit of LSC size is eliminated in one direction.
Modeling and optimization of an FLSC design is presented using polarization-ray tracing under realistic conditions with solar spectrum radiation and broad-band absorption and emission spectra of fluorescence materials with their inevitable self-absorption effect.
Methods and results of fabrication and accurate optical characterization of such FLSC using two off-the-shelf organic dyes and a commercially available polymer, COP, are discussed in detail. Fiber preforms, fabricated under optimized conditions for low light transport loss, are thermally drawn into sub-millimeter-size fibers. Characterization of several samples with various concentrations of the two dyes shows an optical-to-optical conversion efficiency of 9.1% for a tandem combination of two 2.5-cm-long fibers with the efficiency gradually decreasing to 4.9% with increase in fiber length to 10 cm.<br>Ph.D.<br>Doctorate<br>Electrical Engineering and Computer Science<br>Engineering and Computer Science<br>Electrical Engineering
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Pfau, Charlotte [Verfasser], S. [Akademischer Betreuer] Schweizer, R. [Akademischer Betreuer] Wehrspohn, and U. [Akademischer Betreuer] Rogulis. "Low phonon energy glass ceramics for efficient rare-earth luminescence / Charlotte Pfau. Betreuer: S. Schweizer ; R. Wehrspohn ; U. Rogulis." Halle, Saale : Universitäts- und Landesbibliothek Sachsen-Anhalt, 2014. http://d-nb.info/1076503195/34.
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Katayama, Yumiko. "Optical and photo-electric studies on quantum cutting and persistent luminescent phosphors doped with rare-earth and transition-metal ions." Kyoto University, 2014. http://hdl.handle.net/2433/188818.
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Kyoto University (京都大学)<br>0048<br>新制・課程博士<br>博士(人間・環境学)<br>甲第18380号<br>人博第693号<br>新制||人||166(附属図書館)<br>25||人博||693(吉田南総合図書館)<br>31238<br>京都大学大学院人間・環境学研究科相関環境学専攻<br>(主査)教授 田部 勢津久, 教授 加藤 立久, 教授 杉山 雅人, 教授 森本 芳則, 教授 山本 行男<br>学位規則第4条第1項該当
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Banda, Gnama Mbimbiangoye Mallys Elliazar. "Mesure et modélisation du comportement de matériaux diélectriques irradiés par faisceau d'électrons." Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30208/document.
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Dans leurs usages courants comme isolants électriques, les matériaux solides organiques sont constitutifs aussi bien des câbles de transport d'énergie électrique, des circuits de commande et de conversion de puissance que des composants (micro)électroniques ou des systèmes embarqués (revêtement thermique des satellites, batteries d'accumulateurs...). La diversité des contraintes d'utilisation auxquelles ils sont soumis (champ électrique, rayonnement, température, humidité...) les prédisposent à emmagasiner des charges en leur sein, susceptibles d'affecter la fiabilité des systèmes qui en dépendent. L'un des moyens communément mis en œuvre pour étudier le comportement électrique de ces charges est la mesure de la distribution spatio-temporelle des charges d'espace, en soumettant le diélectrique à une différence de potentiel continue à travers deux électrodes. Cette méthode ne permet cependant pas toujours de distinguer clairement la contribution des charges dues à la génération, d'une part, et celles dues aux phénomènes de transport, d'autre part. Cette étude propose une approche alternative, consistant à déposer sous vide des charges (électrons) au sein de l'isolant par le biais d'un faisceau d'électrons, à une position connue et en quantité maîtrisée, en prenant en compte d'autres processus physiques liés à l'implantation d'électrons afin de prévoir et modéliser le comportement de ces matériaux irradiés. Des films de PolyEthylène basse densité (PEbd), préparés par thermomoulage, ont été irradiés par un faisceau d'électrons de 80 keV avec un flux de 1 nA/cm2. Les mesures de charge d'espace par la méthode Electro-Acoustique Pulsée (PEA), réalisées d'abord in-situ, puis ex-situ sous polarisation électrique DC, confirment une localisation effective de charges au sein du matériau. Les résultats sous polarisation électrique après irradiation mettent en évidence une importante présence de charges positives dans la zone irradiée du diélectrique. Les caractérisations électriques des films PEbd irradiés montrent un comportement complètement différent de celui d'un même matériau non-irradié, laissant penser à une modification de la structure chimique du matériau. Des mesures physico-chimiques (spectroscopie infra-rouge, Photoluminescence et Analyse Enthalpique Différentielle-DSC) sur ces films PEbd irradiés, ne montrent pas une dégradation significative de la structure chimique du diélectrique qui expliquerait le comportement électrique observé sous polarisation post-irradiation. Des mesures complémentaires montrent le comportement réversible du PEbd irradié puis polarisé, qui serait uniquement lié à la présence des charges générées par le faisceau. Les données expérimentales de cette étude ont parallèlement alimenté un modèle numérique de transport de charges, développé pour tenir compte des contraintes sous irradiation. Ce modèle a permis de reproduire les résultats d'implantation de charge par faisceau d'électrons in-situ ainsi que la majorité des processus électriques observés sur du PEbd irradié puis polarisé. Il confirme l'impact de la charge déposée par faisceau d'électrons sur le comportement sous polarisation et permet de conclure quant à l'origine des charges positives observées post-irradiation, qui seraient dues aussi bien aux phénomènes d'injection aux électrodes qu'à la création de paires électrons/trous par le faisceau d'électrons pendant l'irradiation<br>In their common uses as electrical insulators, organic solid materials are constitutive of electric power transmission cables, power control and conversion circuits as well as (micro) electronic components or embedded systems (thermal coating of satellites, batteries of accumulators, etc.). Under various constraints of use (electric field, radiation, temperature, humidity ...) they can accumulate charges in their bulk which could affect the reliability of the systems in which they are employed. One of the commonly used means to study the electrical behavior of these charges is to measure the spatiotemporal distribution of charges by subjecting the dielectrics to a continuous potential difference between two electrodes. However, this method does not always allow clearly distinguishing the contribution of charges due to generation on the one hand and the one due to transport phenomena on the other hand. This study proposes an alternative approach, consisting in generating charges (electrons) within the electrical insulation using an electron-beam under vacuum. The charges are hence deposited at a known position and in a controlled quantity. Other physical processes related to the implantation of electrons must then be taken into account in order to predict and model the behavior of these irradiated materials. Low-density polyethylene (LDPE) films, prepared by thermal molding, were irradiated by a 80 keV electron-beam with a current flux of 1 nA/cm2. Space charge measurements using the Pulsed Electro-Acoustic (PEA) method, performed first in-situ and then ex-situ under DC electrical polarization, confirm an effective localization of charges within the material. The results under electrical polarization after irradiation show an important amount of positive charges in the irradiated zone of the dielectric. The electrical characterizations of irradiated LDPE films show a completely different behavior compared to the same non-irradiated material, suggesting a modification of the chemical structure of the material. Physico-chemical measurements (infrared spectroscopy, Photoluminescence and Differential Scanning Calorimetry-DSC) on these irradiated PEbd films do not show a significant degradation of the chemical structure of the dielectric which would explain the observed electrical behavior under post-irradiation polarization. Additional measurements show the reversible behavior of the irradiated then polarized PEbd, which would be only related to the presence of the charges generated by the beam. The experimental data of this study have simultaneously fed a numerical model of charge transport, developed to take into account the irradiation constraints. This model allows reproducing the in-situ results of charge implantation by the electron beam as well as the majority of the electrical processes observed on irradiated and polarized LDPE. It confirms the impact of the electron-beam deposited charge on the behavior under polarization and allows concluding on the origin of the positive charges observed after irradiation, which would be due to injection at the electrodes as well as to the creation of electron-hole pairs by the electron-beam during irradiation
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La, Rosa Marcello. "Development of luminescent semiconductor nanocrystals (Quantum Dots) for photoinduced applications." Thesis, Bordeaux, 2017. http://www.theses.fr/2017BORD0591/document.
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Cette thèse s’est focalisée sur le développement de nanocristaux semi-conducteurs luminescents, i.e. des boîtes quantiques (quantum dots, QDs), pour des applications photo-induites. Ces nanomatériaux possèdent des propriétés optiques très intéressantes qui dépendent de leur taille et sont prometteurs pour des applications dans divers domaines.Les QD sont généralement hydrophobes mais de nombreuses applications intéressantes requiert une compatibilité avec l'eau ou du moins avec un environnement polaire. Cela, nécessite donc un traitement post-synthétique afin de modifier leur solubilité.Au cours de cette thèse, une nouvelle méthode pour transférer les QDs d'un solvant apolaire vers un solvant polaire a été développée en les fonctionnalisant avec l'acide lipoïque, un tensioactif complexant.L'acide lipoïque est une molécule chirale générant donc un effet de dichroïsme induit qui a pu être étudier, ainsi que sa dépendance vis-à-vis la taille des nanocristaux.Un objectif clef de ces recherches était le développement de QDs présentant un transfert d'énergie électronique réversible (REET). Il s’agit d’un transfert d'énergie bidirectionnel entre les QDs photoexcités et des unités chromophores appropriées fixées sur leur surface, dont la conséquence la plus importante est l'allongement de la durée de vie de luminescence du QD.Enfin, un nouveau protocole pour le dépôt de QDs chargés sur un substrat vitreux localement polarisé a été développé en collaboration avec le Dr Marc Dussauze de l'Université de Bordeaux<br>This thesis focuses on the development of luminescent semiconductor nanocrystals quantum dots (QDs) for photoinduced applications. QDs are promising nanomaterials with size-dependent optical properties and are attractive for applications in several fields.However, QDs are commonly hydrophobic and many interesting applications require their compatibility with water or at least with a polar environment, meaning a post-synthetic treatment is required to confer a different solubility.During these studies, a new method for transferring QDs from an apolar solvent to another one polar has been successfully developed, by exploiting lipoic acid, as a versatile surface capping agent. Moreover, lipoic acid is a chiral molecule so a possible induced dichroism effect has been also investigated, as well as its dependence on the size of nanocrystals.A major aim of this research was the development of QDs exhibiting reversible electronic energy transfer (REET). Such a process is a bidirectional energy transfer between the photoexcited QDs and suitable chromophoric units attached on their surface, whose most important consequence is the elongation of the luminescence lifetime of the QD. Strong experimental evidence for REET and accompanying modifications of the photophysical properties has been obtained. Such a process to our knowledge has never been observed in QD-based systems.Finally, a novel protocol for depositing charged QDs on a locally polarized glassy substrate has been developed in collaboration with Dr. Marc Dussauze of the University of Bordeaux
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Jayaraj, Balaji. "Correlating microstructural development and failure mechanisms to photo stimulated luminescence spectroscopy and electrochemical impedance spectroscopy in thermal barrier coatings." Doctoral diss., University of Central Florida, 2011. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4948.
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Thermal barrier coatings (TBCs) are widely used for thermal protection of hot section components in turbines for propulsion and power generation. Applications of TBCs based on a clearer understanding of failure mechanisms can help increase the performance and life-cycle cost of advanced gas turbine engines. Development and refinement of robust nondestructive evaluation techniques can also enhance the reliability, availability and maintainability of hot section components in gas turbines engines. In this work, degradation of TBCs was non-destructively examined by photostimulated luminescence spectroscopy (PSLS) and electrochemical impedance spectroscopy (EIS) as a function of furnace thermal cycling carried out in air with 10-minute heat-up, 0.67, 9.6 and 49.6 - hour dwell duration at 1121[degree]C (2050[degree]F), and 10-minute forced-air quench. TBCs examined in this study consisted of either electron beam physical vapor deposited and air plasma sprayed yttria-stabilized zirconia (YSZ) on a variety of bond coat / superalloy substrates including bond coats of NiCoCrAlY and (Ni,Pt)Al, and superalloys of CMSX-4, Rene'N5, Haynes 230 and MAR-M-509. Detailed microstructural characterization by scanning electron microscopy and energy dispersive spectroscopy was carried out to document the degradation and failure characteristics of TBC failure, and correlate results of PSLS and EIS. Mechanisms of microstructural damage initiation and progression varied as a function of TBC architecture and thermal cycling dwell time, and included undulation of the interface between the thermally grown oxide (TGO) and bond coats, internal oxidation of the bond coats, and formation of Ni/Co-rich TGO. These microstructural observations were correlated to the evolution in compressive residual stress in the TGO scale determined by PSLS shift. Correlations include stress-relief and corresponding luminescence shift towards stress-free luminescence (i.e. v= 14402 cm[super-1] and v = 14432 cm[super]-1) associated with subcritical cracking of the TGO scale and stress-relaxation associated with gradual shift in the luminescence towards stress-free luminescence (i.e. v = 14402 cm[super-1] and v = 14432 cm[super-1]) is related to the undulation of TGO/bondcoat interface (e.g., rumpling and ratcheting). Microstructural changes in TBCs such as YSZ sintering, TGO growth, and subcritical damages within the YSZ and TGO scale were also correlated to the changes in electrochemical resistance and capacitance of the YSZ and TGO, respectively. With thermal exposure the YSZ/TGO resistance and capacitance increased and decreased as result of sintering and TGO growth. With progressive thermal cycling damages in the TGO was related to the TGO capacitance showing a continuous increase and at failure TGO capacitance abruptly increased with the exposure of bondcoat. Further correlations among the microstructural development, PSLS and EIS are documented and discussed, particularly as a function of dwell time used during furnace thermal cycling test, with due respect for changes in failure characteristics and mechanisms for various types of TBCs.<br>ID: 029810158; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (Ph.D.)--University of Central Florida, 2011.; Includes bibliographical references (p. 213-217).<br>Ph.D.<br>Doctorate<br>Mechanical, Materials, and Aerospace Engineering<br>Engineering and Computer Science
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Chan, Ka-man Carmen, and 陳嘉敏. "Design and synthesis of luminescent branched multinuclear platinum(II)alkynyl complexes and the study of their two-photon absorptionproperties." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B43703653.
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Giraud, Marion. "Nouveaux diaryléthènes photochromes et photo-commutation des propriétés optiques et magnétiques à l'échelle moléculaire." Paris 11, 2005. http://www.theses.fr/2005PA112241.
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Ce travail présente la synthèse et la caractérisation de composés associant photochromisme et chimie de coordination dans le but d'élaborer des matériaux moléculaires à propriétés photomodulables. Les deux dernières décennies ont vu l'émergence d'un nouveau type de chimie des matériaux où l'on demande aux molécules briques d'être " intelligentes ". En cela le photochromisme a joué un rôle très important dans le développement de ces matériaux photosensibles. Des ligands pontants photochromes de type diaryléthène ont été synthétisés et utilisés pour la synthèse de complexes dinucléaires de Cu(II), Mn(II), Co(II), Ni(II) et Zn(II). Les études de Résonance Paramagnétique Electronique de certains de ces complexes ont montré sous irradiation (i) la modulation réversible des propriétés magnétiques de ces complexes, (ii) l'éjection réversible du métal de la cavité. En vue d'obtenir des systèmes plus complexants, plusieurs voies de fonctionnalisations des diaryléthènes ont été employées pour former des cavités à 4 ou 5 atomes donneurs et la stratégie de post-fonctionnalisation s'avère la plus efficace. Enfin, nous avons conçu des diaryléthènes optimisés pour la Génération de Seconde Harmonique et montré que l'on pouvait moduler l'activité en Optique Non Linéaire de ces composés par irradiation lumineuse<br>This work deals with the syntheses and the characterisations of compounds which are at the crossing of both photochromism and coordination chemistry and whose properties are photo-switchable. These compounds have attracted many interest in the scientific world for they can potentially be used in optoelectronics and photonic devices. We report here on the syntheses and characterisations of chelating diarylethenes and their use as bridges between metallic centres. Dinuclear complexes have been obtained and the Electronic Paramagnetic Resonance investgations, mainly dedicated to the study of a Cu(II) dinuclear complex, have shown both the reversible changes in the magnetic properties of this complex and the reversible release of the metal ion in solution upon irradiation. A structure of a closed isomer of this compound has been obtained. Synthetic methods have been used to bind more chelating sites to the perfluorated core : the post-functionnalisation way has been the most successful of many attempts, leading to new diarylethenes with 4 or 5 donating atoms. Eventually, Non Linear Optics-designed compounds are also described and their luminescence and Second Harmonic Generation switching properties are also reported
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Ring, Josh. "Novel fabrication and testing of light confinement devices." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/novel-fabrication-and-testing-of-light-confinement-devices(51572720-0c49-482e-8523-e44ca877117f).html.
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The goal of this project is to study novel nanoscale excitation volumes, sensitive enoughto study individual chromophores and go on to study new and exciting self assemblyapproaches to this problem. Small excitation volumes may be engineered using light con-finement inside apertures in metal films. These apertures enhance fluorescence emissionrates, quantum yields, decrease fluorescence quenching, enable higher signal-to-noiseratios and allow higher concentration single chromophore fluorescence, to be studied byrestricting this excitation volume. Excitation volumes are reported on using the chro-mophore's fluorescence by utilising fluorescence correlation spectroscopy, which monitorsfluctuations in fluorescence intensity. From the correlation in time, we can find the res-idence time, the number of chromophores, the volume in which they are diffusing andtherefore the fluorescence emission efficiency. Fluorescence properties are a probe ofthe local environment, a particularly powerful tool due to the high brightness (quantumyield) fluorescent dyes and sensitive photo-detection equipment both of which are readilyavailable, (such as avalanche photodiodes and photomultiplier tubes). Novel materialscombining the properties of conducting and non-conducting materials at scales muchsmaller than the incident wavelength are known as meta-materials. These allow combi-nations of properties not usually possible in natural materials at optical frequencies. Theproperties reported so far include; negative refraction, negative phase velocity, fluorescenceemission enhancement, lensing and therefore light confinement has also been proposed tobe possible. Instead of expensive and slow lithography methods many of these materialsmay be fabricated with self assembly techniques, which are truly nanoscopic and otherwiseinaccessible with even the most sophisticated equipment. It was found that nanoscaled volumes from ZMW and HMMs based on NW arrays wereall inefficient at enhancing fluorescence. The primary cause was the reduced fluorescencelifetime reducing the fluorescence efficiency, which runs contrary to some commentatorsin the literature. NW based lensing was found to possible in the blue region of the opticalspectrum in a HMM, without the background fluorescence normally associated with a PAAtemplate. This was achieved using a pseudo-ordered array of relatively large nanowireswith a period just smaller than lambda / 2 which minimised losses. Nanowires in the traditionalregime lambda / 10 produced significant scattering and lead to diffraction, such that they werewholly unsuitable for an optical lensing application.
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Chan, Ka-man Carmen. "Design and synthesis of luminescent branched multinuclear platinum(II) alkynyl complexes and the study of their two-photon absorption properties." Click to view the E-thesis via HKUTO, 2010. http://sunzi.lib.hku.hk/hkuto/record/B43703653.
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