Les applications présentées dans cette thèse valorisent de diverses manières le principe d'ablation laser, c'est à dire l'arrachement de la matière d'une surface solide suite à l'irradiation avec un faisceau laser. Le plasma généré par irradiation laser impulsionnel a été utilisé pour le dépôt de couches minces ou de nanoparticules et pour l'analyse compositionnelle des couches d'épaisseur nanométrique. Nous avons synthétisé par dépôt laser combinatoire des librairies compositionnelles d'un oxyde mixte transparent d'In et Zn. En utilisant le plasma d'ablation pour le diagnostic compositionnel, nous avons déterminé les concentrations d'indium et de zinc dans les couches minces par spectroscopie laser. Des couches minces de bioverre ont été synthétisées par dépôt laser impulsionnel sur des substrats de titane. En contact avec des cellules ostéoblastes, les bioverres ont stimulé la prolifération et ont augmenté la viabilité. La prolifération des ostéoblastes cultivés sur les couches de bioverre a été 30% supérieure a l'échantillon de contrôle. On a déposé par PLD des couches minces ou nanoparticules adhérentes de ZnO sur des substrats textiles hydrophiles dans un flux d'oxygène ou sous vide pour obtenir des structures avec différentes mouillabilités. En augmentant le nombre d'impulsions laser de 10 à 100 nous avons observé la transition du recouvrement par des nanoparticules isolées vers des couches minces. En fonction de l'atmosphère environnant lors du dépôt, les couches minces et les nanoparticules ont changé leur mouillabilité, passant d'hydrophile en flux d'oxygène à un comportement superhydrophobe (angle de contact de 157°) en cas de dépôt sous vide. / The applications presented in this thesis exploit in different modes the principle of laser ablation, i.e. the material removal from a solid surface following irradiation with a pulsed laser beam. The plasma generated by laser ablation was used for thin films or nanoparticles deposition and for the compositional analysis of nanometric thin films. We synthesized by combinatorial pulsed laser deposition, thin film libraries of a complex oxide of In and Zn. Using the ablation plasma for compositional diagnostic, we determined the In and Zn concentrations in films by Laser Induced Breakdown Spectroscopy using a procedure based on the spectral luminance calculation of a plasma in local thermodynamic equilibrium. Thin films of bioactive glass were synthesized by pulsed laser deposition, magnetron sputtering and MAPLE on Ti substrates and tested the transfer accuracy by physico-chemical tests and their functionality in vitro. In contact with human osteoblast cells, the bioactive glasses stimulated their proliferation and enhanced their viability. The proliferation of osteoblasts cultivated on bioactive films was 30% superior to the control sample. ZnO thin films or nanoparticles were deposited on hydrophilic textile substrates in oxygen flux or in vacuum in order to obtain structures with different wetting behavior. Increasing the number of laser pulses from 10 to 100, we observed a coating transition from isolated nanoparticles to thin films fully coating the textile fibers. Function of the ambient atmosphere during experiments, the structures changed their wetting behavior, passing from hydrophilic in oxygen flux to superhydrophobic (157°) in case of deposition in vacuum.

The automotive industry is expected to transition from a net-consumer to a net-producer of aluminum scrap as aluminum-intensive vehicles (AIVs, i.e., Ford’s aluminum-bodied F-150) begin to reach end-of-life (EOL). In the past, the industry has downcycled aluminum scrap to meet the consumption demands of the automotive sector. With the shift to having a large supply of this scrap in the near future, the industry needs to recover and reuse EOL Al by utilizing a circular economic model, create value via an upcycling paradigm (vs downcycling). This work establishes a platform as to how the recycling industry can be restructured to create value in our waste streams and is organized in three segments: First, an analysis of the flow of automobiles at EOL was carried out from the perspective of recovery and reuse; a recycling rate for Al has been determined, and the factors that go into the dynamics of the recycling rate have been identified. Secondly, the current state of the market was surveyed to evaluate where improvements could be made to affect material collection and recovery. The latter led to compositional characterization of aluminum auto-shred to identify the alloys in the mixture, and thereby the needed intelligent sorting systems for upcycling. Thirdly, these results were used in a dynamic material flow model to predict how the composition of auto-shred will change due to increased aluminum usage and as a function of various end-of-life processing scenarios. The outcome and impact of this work is that we have established a platform that enables the ELV recycling industry to upcycle the large amount of Al that will be available in the near future. These results will be discussed and reviewed during this presentation.

LIBS é um método baseado na espectrometria de emissão óptica que emprega a microamostragem por ablação por laser e formação de um microplasma para a determinação dos elementos químicos presentes na amostra. Neste trabalho, o método foi avaliado para a análise de embalagens plásticas produzidas com polietileno de alta densidade e polipropileno. A construção de curvas de calibração com amostras dos polímeros contendo diferentes concentrações de Cd, Cr e Pb e a determinação desses analitos, assim como os efeitos da taxa de repetição do laser, número de pulsos, fluência e diâmetro de focalização foram estudados. O sistema LIBS utilizado foi composto por um laser pulsado de Nd:YAG operando a 064 nm, com pulsos de 5 ns e máxima energia de 360 mJ/pulso. Os sinais de emissão foram coletados por um conjunto de lentes acoplado por fibra óptica ao espectrômetro com montagem Echelle e detector ICCD. Os parâmetros instrumentais foram ajustados em 10 pulsos acumulados, 2 \'mü\'s de atraso e 6 \'mü\'s de integração. O software ESAWIN, o banco de dados de espectros atômicos e iônicos do NIST e algoritmo desenvolvido em ambiente MATLAB® foram utilizados para aquisição e tratamento dos dados. A avaliação da topografia das crateras nas placas dos polímeros foi feita por perfilometria e microscopia eletrônica de varredura, que proporcionaram informações úteis para a caracterização das crateras. As massas removidas das placas de polietileno de alta densidade e de polipropileno foram calculadas a partir dos volumes das crateras obtidos pelas análises perfilométricas. A taxa de repetição e número de pulsos do laser tiveram efeitos marcantes na ablação dos polímeros, e as principais causas foram atribuídas ao grau de cristalinidade, à temperatura de fusão cristalina (Tm) e à temperatura de transição vítrea (Tg). Os resultados desta tese indicaram que diâmetros de focalização da ordem de 600 \'mü\'m e fluências entre 50 e 85 J cm-2 podem ser recomendados para análises de PEAD e PP por LIBS com laser de Nd:YAG@1064 nm (pulsos de 5 ns) e taxa de repetição de 10Hz. Nessas condições, as curvas de calibração obtidas apresentaram boa correlação. Identificaram-se três amostras contaminadas por Cd, Cr e Pb dentre 60 embalagens plásticas analisadas. A comparação dos resultados obtidos por LIBS e ICP OES apresentou concordâncias e algumas diferenças significativas (teste t ao nível de 95% de probabilidade) que foram associadas a efeitos de matriz observados na análise dos polímeros por LIBS / LIBS is an optical emission spectroscopy technique that employs a laser for micro sampling and induction of a plasma for determination of chemical elements in a sample. In this work, LIBS was evaluated for the analysis of plastic packaging produced with high density polyethylene (HDPE) and polypropylene (PP). Plates of these polymers with different concentrations of Cd, Cr and Pb were prepared for evaluating the effects of laser repetition rate, number of pulses, fluence and laser focusing as well as for building the analytical calibration curves. The LIBS system was designed by using a Q-Switch Nd:YAG laser operating at 1064 nm (5 ns, 360 mJ/pulse) and the emission signals were collected by lenses into an optical fiber coupled to a high-resolution echelle spectrometer equipped with ICCD. Instrumental parameters consisted of 10 accumulated laser pulses, 2 \'mü\'s delay time and 6 \'mü\'s integration time gate. Software ESAWIN, NIST atomic database and an algorithm develop in MATLAB® were used for acquisition and data processing. The evaluation of topographical features of craters on the plates of the polymers was carried out by perfilometry and scanning electron microscopy, and provides useful information for the characterization of the craters. The mass removal of HDPE and PP were calculated using craters volume obtained in perfilometric analysis. The repetition rate and number of laser pulses affect the ablation process in polymers. Moreover, the main properties of polymers that affect the ablation are degree of crystallinity, crystalline melting temperature (Tm) and glass transition temperature (Tg). The results indicated that laser focusing of 610 \'mü\'m and fluences between 50 and 85 J cm-2 can be indicated for LIBS analysis of HDPE and PP with Nd:YAG@1064 nm, 5 ns and 10 Hz. Under these conditions the calibration curves obtained presented good correlations and 3 samples containing Cd, Cr and Pb were identified from 60 samples from the local market. LIBS results compared well with ICP OES but some data presented significant differences by applying a t-test at 95 % confidence level, which were mainly associated to matrix effects observed in the analysis of polymers by LIBS

A influência das variáveis associadas ao laser como a fluência, o comprimento de onda, e a duração do pulso, assim como as relacionadas às propriedades das amostras, como a distribuição do tamanho das partículas e as características químicas da matriz, foram avaliadas visando à determinação quantitativa de macro- (P, K, Ca, Mg) e micronutrientes (Cu, Fe, Mn, Zn, B) em pastilhas de materiais vegetais por espectrometria de emissão óptica com plasma induzido por laser (LIBS). Os efeitos da distribuição do tamanho das partículas e da fluência do laser foram investigados a partir da análise de amostras peneiradas (150-20 µm) empregando-se um sistema LIBS, em regime temporal de nanossegundos (ns-LIBS), montado com um laser de Nd:YAG a 1064 nm (pulsos de 5 ns e 360 mJ)e um espectrômetro com óptica Echelle e detector ICCD. Observou-se um aumento na sensibilidade e na precisão das medições com a diminuição do tamanho das partículas usadas no preparo das pastilhas, e uma diminuição dos efeitos de matriz causados por diferenças no tamanho das partículas, quando pastilhas preparadas com partículas < 75 µm foram analisadas com pulsos de 50 J cm-2. Verificou-se uma melhora significativa na exatidão das medições de Mg, Fe, Mn e Zn feitas em um conjunto de pastilhas de folhas de cana-de-açúcar (partículas < 75 µm) empregando-se esta fluência. Em uma segunda etapa, observou-se que variações no comprimento de onda do laser de Nd:YAG (1064, 532, 355 e 266 nm) não influenciaram de maneira significativa a precisão e exatidão das medições em pastilhas de folhas de cana-de-açúcar, obtendo-se correlações lineares entre as intensidades dos sinais de emissão e as correspondentes frações de massa dos analitos. Variações no comprimento de onda do laser de Nd:YAG não afetaram a análise de um conjunto heterogêneo de amostras, composto por pastilhas de folhas de plantas de diferentes espécies, como soja, cana-de-açúcar, milho, citros, café, por exemplo, por ns-LIBS. No entanto, diferentemente do observado para o conjunto de pastilhas de folhas de cana-de-açúcar, observou-se, uma baixa correlação (r cal < 0,90) entre as frações de massa de Ca, Mg, P, Cu, Fe, Mn e Zn determinadas por ns-LIBS e os valores de referência, o que demonstra a baixa robustez de ns-LIBS frente às variações na composição química das matrizes. Posteriormente, analisou-se este conjunto heterogêneo de amostras com sistema LIBS, em regime temporal de femtossegundos (fs-LIBS), montado com laser de Ti:Safira (pulsos de 60 fs e 1,65 mJ) e espectrômetro com óptica Czerny-Turner e ICCD. Demonstrou-se que o uso de pulsos em regime de fs proporcionou calibrações e validação menos dependentes da composição química das matrizes. As frações de massa de Ca, Mg, P, Fe e Mn previstas por fs-LIBS foram estatisticamente concordantes com os valores de referência, independentemente do modelo de calibração usado. Além disso, o uso de calibração multivariada melhorou a capacidade preditiva de ns-LIBS, assemelhando-se à de fs-LIBS. Concluiu-se que o emprego de fs-LIBS foi a estratégia mais robusta e que ofereceu maior flexibilidade à variabilidade matricial / The influence of laser properties, such as fluence, wavelength and pulse duration, as well as sample characteristics, such as particle size distribution and chemical matrix composition, was evaluated aiming at the quantitative determination of macro- (P, K, Ca, Mg) and micronutrients (Cu, Fe, Mn, Zn, B) in pellets of plant materials by laser-induced breakdown spectroscopy (LIBS). Firstly, the effects of particle size distribution and laser fluence on the analysis of pellets (test samples) prepared with sieved samples (from 150 to 20 µm apertures) were investigated. Experiments were carried out with a nanosecond LIBS (ns-LIBS) system by using a Q-switched Nd:YAG laser at 1064 nm (5 ns; 360 mJ) and a spectrometer with Echelle optics and intensified charge-coupled device (ICCD) detector. Results indicated that smaller particles yielded to sensitivities\' enhancement and attained better measurements\' precision. Moreover, matrix effects were reduced by analyzing pellets prepared from < 75 ?m sieved fractions and pulses of 50 J cm-2. In addition, there was a significant improvement on accuracy of Mg, Fe, Mn and Zn measurements in a set of test samples of sugarcane leaves by using this fluence. In a second experiment, variations in the Nd:YAG laser wavelength (1064, 532, 355 and 266 nm) did not affect the analysis of test samples of sugarcane leaves, and provided linear correlations between emission signal intensities and corresponding analytes mass fractions. In addition, variations within Nd:YAG laser wavelength did not affect the analysis of a heterogeneous sample set composed by pellets of leaves from different crops, such as soy, sugarcane, maize, citrus and coffee by ns-LIBS. However, in contrast to previous findings, the univariate calibration models for ns-LIBS presented lower linearity (r cal < 0.90) for Ca, Mg, P, Cu, Fe, Mn and Zn, no matter the laser wavelength used for the analysis. These circumstances reflect the low robustness of ns-LIBS to variations within matrix chemical composition among test samples. Afterwards, test samples from different crops were analyzed by a femtosecond LIBS (fs-LIBS) by using a Ti:Sapphire laser, including a mode-locked oscillator and an ultrafast amplifier (60 fs; 1.65 mJ per pulse), and a spectrometer with Czerny-Turner optics and ICCD. Findings indicated that the pulse duration was a decisive variable for providing accurate quantification of nutrients in different plant species, which present substantial differences in terms of matrix chemical composition. Close agreement between Ca, Mg, P, Fe and Mn mass fractions predicted by fs-LIBS and those determined by ICP OES was evidenced, whatever the modeling approach used. Contrarily, for ns-LIBS analysis of test samples from different crops, only the use of multivariate partial least squares (PLS) regression appears capable for resolving the non-linear transformations of the emission intensities according to the physical mechanisms governing this temporal regime of ablation. Thus, when using multivariate modeling, the figures-of merit reflecting the predictive capabilities of ns-LIBS resemble to those achieved by fs-LIBS. Either way, fs-LIBS is a more robust approach that better offers larger flexibility to the matrix variability

Com clima diversificado e terras férteis, o Brasil tem vocação natural para o desenvolvimento agropecuário e todas as suas vertentes. Assim, o agronegócio é hoje a principal locomotiva da economia brasileira, representando cerca de um terço do nosso Produto Interno Bruto (PIB). Nesse contexto, o Brasil é o terceiro maior produtor de frutas do planeta, com destaque para a produção de laranjas. Particularmente, o país lidera a produção mundial de suco de laranja e conta com uma participação de 85% nas exportações deste produto. Porém, um dos principais fatores atuais que restringem os lucros e a expansão da citricultura é o controle fitossanitário. Atualmente, dentre as principais doenças podemos destacar o HLB e o cancro cítrico. Ambas, doenças bacterianas que não têm cura comprometem a produção e desenvolvimento da fruta e levam à morte da árvore. Dessa maneira, o monitoramento destas é fundamental para evitar danos aos frutos e a necessidade da erradicação de plantações inteiras. O presente trabalho avaliou o emprego das técnicas de Espectroscopia de Fluorescência Induzida por Laser (LIFS) e Espectroscopia de Emissão Óptica com Plasma Induzido por Laser (LIBS) como forma de diagnóstico destas doenças, se apresentando como uma alternativa às inspeções visuais e ao PCR utilizados atualmente. Para isso, folhas de citros in natura provenientes de plantas sadias, com HLB ou com cancro foram amostradas e medidas com ambos os sistemas. Através do sistema LIFS foi realizado um estudo de precocidade no diagnóstico do HLB. Este sistema fotônico pôde detectar a doença até 21 meses antes do aparecimento dos primeiros sintomas visuais. Foram utilizados classificadores sazonais, criados a partir de Regressão por Mínimos Quadrados Parciais (PLSR) e conjuntos de calibração previamente avaliados. Quanto ao cancro cítrico e o sistema LIFS, taxas de acerto superiores a 90% foram alcançadas nos melhores casos de validação cruzada dos dados. A diferenciação do cancro e do HLB também foi possível pela mesma técnica ao avaliar um conjunto pequeno de dados, que atingiu uma taxa de acerto de 82%. Através dos espectros obtidos pelo sistema LIBS, avaliou-se as variações nutricionais causadas na planta devido à doença. Por meio de tais variações e métodos de PLSR foi construído um modelo para o diagnóstico de HLB alcançando taxas de acerto da ordem de 75%. Em relação ao cancro cítrico e o sistema LIBS, um estudo preliminar foi realizado, e uma taxa de acerto superior a 90% foi atingida. Por fim, os resultados corroboraram com a ideia inicial de se realizar o diagnóstico do HLB e do cancro cítrico através de técnicas fotônicas. Dentre outras vantagens estas permitem uma análise rápida, in loco, sem a necessidade de preparo de amostra. Além disso, para o HLB, as técnicas fotônicas demonstraram menor sensibilidade à distribuição não homogênea da doença, quando comparada com a técnica de referência (qPCR). / The diverse climate and fertile soils make Brazil a country with a natural vocation for agricultural development. Thus, agribusiness is now the main locomotive of the Brazilian economy, accounting for about one-third of our Gross Domestic Product (GDP). In this context, Brazil is the third largest fruit producer in the world, with emphasis on the orange production. Particularly, the country leads the world production of orange juice, and with a stake of 85% in exports of this product. However, one of the main factors that restrict current profits and the expansion of citrus production is phytosanitary control. Currently, among the major diseases we highlight the HLB (Greening) and Citrus Canker, two bacterial diseases that have no cure and affect production and fruit development. Therefore, monitoring is essential to prevent damage to the fruits and the complete eradication of infected orchards. The present study evaluated the use of Laser-Induced Fluorescence Spectroscopy (LIFS) and Laser-Induced Breakdown Spectroscopy (LIBS) techniques as alternative diagnostic methods to visual inspection and PCR technique, currently used. For that, citrus leaves from healthy, HLB or citrus canker infected plants, were sampled and measured with both systems. Through LIFS system, a study of the HLB early diagnosis was done. This photonic system could detect the disease up to 21 months before the tree show the visual symptoms. Seasonal classifiers were used, which were designed from Partial Least Square Regression (PLSR) methods and calibration database previously acquired. Regarding citrus canker and LIFS system, success rates higher than 90% were achieved in the best cases. The differentiation between citrus canker and HLB was also possible using the same technique reaching a success rate around 82%. Through the spectrum obtained by LIBS system, it was evaluated the nutritional variations caused in the plant due to HLB, and based on these data, the diagnosis was done. The average success rate was 75%, which was achieved by PLSR model. Regarding on citrus canker and LIBS system, a preliminary study was carried out and a success rate greater than 90% was achieved. Finally, the results corroborated with the use of photonic techniques for the HLB and citrus canker diagnosis. Among other advantages, they allow rapid analysis, in loco and without the need of sample preparation. In addition, for the HLB, photonics techniques showed lower sensitivity to the non-homogeneous distribution of the disease when compared with the reference technique (qPCR).

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

This thesis contains the results of optical flame emission measurements of the Vulcain 2.1engine and the plasma emission spectroscopy of the Lumen Project engine. The plume spectroscopyis analyzed, ordered and studied in detail to offer the best possible molecular composition.The main focus relied on the hydroxide radical, blue radiation and other moleculesanalysis of the intensities encountered during the tests. The plasma emission spectroscopy isfocused on the determination of the plasma temperature value in LIBS measurements. Thehydrogen plasma temperature determination of the local thermodynamic equilibrium, followedby the carbon and sequentially oxygen plasma is obtained. The quality of the LTE isto be determined to judge the truthworthness of the determined temperatures. Both the testsare analyzed thanks to the use of spectrographs, cameras and dedicated software for opticalapplications. The results related to the Vulcain 2.1 LOX/LH2 engine showed the evolutionof the plume in different ROF or pressure variations. Furthermore, the results of the LumenProject LOX/methane engine led to the determination of the plasma temperatures and a firstestimation of the LTE quality. / Die vorliegende Arbeit präsentiert die Ergebnisse der Abgasstrahlspektroskopie des H2/LOXVulcain 2.1 Triebwerks und der Zündplasma Spektroskopie des CH4/LOX Triebwerks desLUMEN Projektes. Die Abgasstrahlspektroskopie wurde analysiert und im Detail untersuchtum die am besten passende molekulare Zusammensetzung herauszuarbeiten. DasHauptaugenmerk liegt dabei auf dem Hydroxyl- Radikal, der Blauen Strahlung und molekularerIntensitätsanalyse. Bei der Zündplasmaanalyse liegt der Fokus auf der Bestimmungdes LTE Zustands (Lokales thermodynamisches Gleichgewicht) in LIBS. Die Temperaturdes Wasserstoff-, Kohlenstoff und Sauerstoffplasmas wird herangezogen, um die Qualitätdes LTE Zustands zu beurteilen. Für die Testdurchführung wurden Spektrographen, Kamerasund bestimmte Auswertungstools für optische Anwendungen benutzt. Das Verhaltendes Vulcain 2.1 Abgasstrahls abhängig von verschiedenen ROF und Druckstufen ist in denErgebnissen beschrieben. Für das LUMEN Triebwerk konnten erste Zündplasmatemperaturenbestimmt werden und geben einen Rückschluss auf die Qualität des LTE.

Τα τελευταία χρόνια, η φασματοσκοπία πλάσματος επαγόμενο από λέιζερ (LIBS) έχει προσελκύσει μεγάλο ερευνητικό ενδιαφέρον καθώς αποτελεί μία πειραματικά απλή και αποτελεσματική τεχνική, η οποία παρέχει τη δυνατότητα λήψης μετρήσεων για απευθείας ποιοτική και ποσοτική στοιχειακή ανάλυση. Η τεχνική LIBS στηρίζεται στη δημιουργία σπινθήρα/πλάσματος μέσω ισχυρά εστιασμένης δέσμης λέιζερ στην επιφάνεια ή στο εσωτερικό του δείγματος, στην ακόλουθη διέγερση και ατομοποίηση των στοιχείων του στόχου και στην τελική καταγραφή και φασματοσκοπική ανάλυση της εκπεμπόμενης ακτινοβολίας του πλάσματος. Λόγω των πολλών πλεονεκτημάτων που συγκεντρώνει η τεχνική, το LIBS έχει προταθεί για πληθώρα πρακτικών, τεχνικών και τεχνολογικών εφαρμογών σε ένα ευρύ φάσμα ερευνητικών πεδίων. Από την άλλη μεριά, στον τομέα της καύσης, η ποσότητα καυσίμου σε ένα εύφλεκτο μίγμα είναι αντικείμενο μείζονος σημασίας καθώς επηρεάζει σημαντικά την απόδοση των χημικών διεργασιών και την παραγωγή και εκπομπή ρύπων. Επομένως, δημιουργείται η ανάγκη ανάπτυξης μίας γρήγορης και μη παρεμβατικής διαγνωστικής τεχνικής για τη μέτρηση της περιεκτικότητας του καυσίμου τοπικά στη φλόγα με καλή τόσο χωρική όσο και χρονική ανάλυση. Στα πλαίσια της παρούσας διδακτορικής διατριβής, η τεχνική LIBS η οποία συγκεντρώνει όλα αυτά τα πλεονεκτήματα χρησιμοποιήθηκε για αυτό το σκοπό. Κατά τη διάρκεια των πειραμάτων, χρησιμοποιήθηκαν πηγές λέιζερ διάρκειας παλμών ns και fs, ενώ τα συστήματα καύσης που μελετήθηκαν ήταν φλόγες υδρογονανθράκων-αέρα, στρωτής και τυρβώδους ροής, απλής και συνθετότερης γεωμετρίας. Από τα LIBS φάσματα φλογών διαφορετικής σύστασης, προέκυψε λοιπόν ότι υπάρχει μία ισχυρή εξάρτηση μεταξύ των εντάσεων διαφόρων φασματικών γραμμών με το λόγο ισοδυναμίας. Επομένως, μέσω της συσχέτισης αυτής μπορεί να επιτευχθεί με μεγάλη ακρίβεια τόσο η μέτρηση της περιεκτικότητα σε καύσιμο φλογών άγνωστης σύστασης όπως επίσης και η μέτρηση της κατανομής του καυσίμου τοπικά μέσα σε όλη την έκταση της φλόγας παρέχοντας σημαντικές πληροφορίες για την δομή της. Τέλος, εφαρμόστηκε μία παραπλήσια διαγνωστική τεχνική, κατά την οποία η διηλεκτρική κατάρρευση του μέσου ήταν αποτέλεσμα ενός ηλεκτρικού σπινθήρα: electrical Spark Induced Breakdown Spectroscopy (SIBS) όπου και πραγματοποιήθηκε η συγκριτική μελέτη της ακτινοβολίας του πλάσματος επαγόμενο μέσω οπτικής και ηλεκτρικής διέγερσης. / Laser induced breakdown spectroscopy (LIBS) has attracted a lot of scientific interest during the last two decades as it is generally considered to be an experimentally simple and efficient laser-based technique which can perform real-time, qualitative and quantitative elemental analysis. The basic idea of LIBS is the creation of spark/plasma through tight focusing of a laser beam on the surface or into a sample, the subsequent excitation and atomization of the species of the sample at the location where the spark is formed and the final detection and spectroscopic analysis of the emitted radiation from the decaying plasma. Seeing the numerous advantages holding the technique, LIBS has been proposed for many practical, technical and technological applications in various scientific areas. On the other hand, in the field of combustion, the proportion of fuel in a combustible mixture is of great importance as it strongly affects the efficiency of the chemical processes and the production of soot emissions. Therefore, there is a continuously increasing need for the development of a rapid and non-perturbative diagnostic technique for the determination of the fuel content locally in the flame structure with good spatial and temporal resolution. Ιn the present dissertation, LIBS technique which offers such advantages has been applied for combustion diagnostics purposes. During the experiments, laser systems with pulse duration in the scale of ns and fs have been applied as excitation sources, while the combustible mixtures under investigation were hydrocarbon-air flames, of laminar and turbulent flow with simple and more complicated structures. From the LIBS spectra in flames of different compositions, it was exhibited that there is a strong dependence of the intensities of various spectral lines on the equivalence ratio, which demonstrates that the precise determination of the amount of fuel can be performed. Also based on this correlation, the determination of the equivalence ratio locally everywhere within the flame can be achieved giving useful information about its structure. Finally, a similar diagnostic technique has been employed. The dielectric breakdown is held using a spark generator and the technique is called electrical Spark Induced Breakdown Spectroscopy (SIBS). The emitted light of the two plasmas induced by optical and electrical excitation was collected and a comparative study was performed.

Laser-Induced Breakdown Spectroscopy (LIBS) is an analytical technique that has the potential to detect all the elements present in the periodic table. The limit of detection can go below a few ppm and this regardless of the physical phase of the analyzed sample (solid, liquid or gas). Its simplicity of use, its rapidity to get results and its versatility provide this technique with attractive features. The technique is currently developed for applications in a large number of domains such as online control, spatial explorations and the environment. However the weakness of the LIBS technique, compared to other more conventional ones, is still its difficulty in providing reliable quantitative results, especially for inhomogeneous and complex matrix such as organic or biological materials. The work presented in this thesis includes a study of the properties of plasma induced from different organic materials. First, a study of the plasma induced on the surface of a Nylon sample at short time delays (~ns) was carried out using the time-resolved shadowgraph technique for different experimental parameters (laser energy, pulse duration, wavelength). Then, a complete diagnostics of the plasma was performed using the plasma emission spectroscopy. A detailed analysis of the emission spectra at different detection delays allowed us to determine the evolution of the temperatures of the different species in the plasma (atoms, ions and molecules). The homogeneity and the local thermodynamic equilibrium within the plasma was then experimentally checked and validated. We demonstrated that the optimisation of the signalto- noise ratio and a quantitative procedure, such as the calibration-free LIBS, can be put in place within a properly chosen detection window. In our experiments, such optimised detection configuration was further employed to record LIBS spectra from different families of polymer in order to identify and classify them. For this purpose, the chemometrics procedure of artificial neural networks (ANN) was used to process the recorded LIBS spectroscopic data. The promising results obtained in this thesis makes LIBS stand out as a potentially useful tool for real time identification of plastic materials. Finally, this work can also be considered as a base for the further studies of more complex materials such as biological tissues with LIBS.

Submitted by Bruna Rodrigues (bruna92rodrigues@yahoo.com.br) on 2016-09-15T20:31:27Z No. of bitstreams: 1 DissECA.pdf: 4704364 bytes, checksum: 1909457a146bdb29a74ad65130ca2bd9 (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-09-16T19:58:59Z (GMT) No. of bitstreams: 1 DissECA.pdf: 4704364 bytes, checksum: 1909457a146bdb29a74ad65130ca2bd9 (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-09-16T19:59:07Z (GMT) No. of bitstreams: 1 DissECA.pdf: 4704364 bytes, checksum: 1909457a146bdb29a74ad65130ca2bd9 (MD5) / Made available in DSpace on 2016-09-16T19:59:13Z (GMT). No. of bitstreams: 1 DissECA.pdf: 4704364 bytes, checksum: 1909457a146bdb29a74ad65130ca2bd9 (MD5) Previous issue date: 2015-03-27 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Coarse particulate matter with aerodynamic diameter smaller than 10μm (PM10) have long been considered as air pollutants associated with health issues. They penetrate into the upper respiratory tract, causing respiratory problems such as worsening of asthma. The aim of this study was to determine and quantify the distribution of chemical elements in the PM10 particulate matter present in the atmosphere of the city of Sao Carlos (Sao Paulo). Samples were collected daily for a period of 23h and 30 minutes, from April 16, 2014 to April 16, 2015. A high-volume sampler (AGV-PM10) with micro quartz and fiber glass filters were used. The filters were subjected to gravimetric analysis to obtain the mass of PM10 and were then analyzed by energy dispersive X-ray fluorescence and Laser Induced Breakdown Spectroscopy to identify and quantify the chemical composition of the samples. The highest average concentration during twelve-month period was 70.41μg/m³ (August, 2014) and the smallest was 22.59μg/m³ (January, 2015). The annual arithmetic average found for the twelve months period was 42.71μg/m³. If compared with annual arithmetic average limit of 40μg/m³, established by CETESB, the value is slightly above and below 50 μg/m³ (CONAMA). If we consider the limit established by the World Health Organization (WHO), which is 20μg/m³, this value is much higher than recommended. The chemicals elements found were characteristic of urban areas / O material particulado, cujo diâmetro aerodinâmico é menor do que 10μm vem sendo considerado como poluente atmosférico muito associado a questões de saúde, uma vez que são os que penetram em vias respiratórias, agravando problemas como o da asma, por exemplo. O objetivo deste trabalho foi avaliar os níveis de concentração de material particulado (MP10) e determinar a distribuição dos elementos químicos deste material particulado presente no ar atmosférico do centro da cidade de São Carlos (São Paulo). As amostras foram coletadas diariamente, por um período de 23h e 30 minutos, entre 16 de abril de 2014 a 16 de abril de 2015. Foi utilizado um amostrador de grandes volumes (AGV-MP10), submetendo os filtros, de fibra de vidro e de micro quartzo, à análise gravimétrica para obtenção de massa de MP10, Fluorescência de Raios-X de Energia Dispersiva de (EDX) e a Espectroscopia de ruptura induzida por laser (LIBS) para identificação e quantificação da composição química elementar das amostras. A maior concentração média do período de doze meses amostrado foi de 70,41μg/m³ em agosto/2014 e a menor de 22,59μg/m³ em janeiro/2015. A média aritmética anual encontrada para o período de doze meses foi de 42,71μg/m³. Se comparada com a média aritmética anual do limite estabelecido pela CETESB, de 40μg/m³, o valor está um pouco acima e um pouco abaixo de 50 μg/m³(CONAMA). Se for considerado o limite estabelecido pela Organização Mundial da Saúde (OMS), que é de 20 μg/m³, este valor encontra-se muito acima do recomendado. Os elementos químicos encontrados são característicos de áreas urbanas e apresentam resultados semelhantes a estudos anteriores na cidade.