Le contexte de cette thèse est la production du vecteur énergétique hydrogène par thermolyse de la vapeur d’eau consistant en la dissociation de la molécule H2O en oxygène (O) et hydrogène (H). Le dispositif employé est une torche à plasma d’arc non transféré développée au LAEPT. Après l’exposition de la théorie sur la physique des plasmas et la spectrométrie d’émission atomique nécessaire à l’exploitation des mesures, cette thèse présente l’évolution de la torche à plasma ainsi que son environnement nécessitée par la présence de gaz instables et explosifs. Les mesures des différentes grandeurs électriques, hydrauliques et spéctrométriques ont permis la détermination des caractéristiques physique et chimique d’un plasma formé d’un mélange de vapeur d’eau – d’argon. La détermination de grandeurs telles que la température du jet plasma, la conductivité électrique, l’enthalpie massique et la densité électronique, est basée sur la comparaison entre expérimentation et théorie. / The context of this thesis is the production of hydrogen as an energy vector by steam thermolysis consisting in the dissociation of H2O molecule into oxygen (O) and hydrogen (H). The process used is a plasma torch device developed by the LAEPT. After presenting the theory of plasma physics and atomic emission spectroscopy which will help to make the most of the measured realized, this thesis will show the evolution of the plasma torch device and the experimental environment required to work with explosive and unstable gases. Some measurements like electrical, hydraulic and spectroscopy magnitudes made it possible to determine the chemical and physical characteristics of a water vapor – argon plasma. A comparison between experiments and theoretical knowledge will enable to determine the temperature of a flow of plasma, electrical conductivity, enthalpy and the electronic density.

Made available in DSpace on 2015-05-14T13:21:30Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 12264651 bytes, checksum: c1dad0a27d50ddb05acdcc8e21042b61 (MD5) Previous issue date: 2012-09-11 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / In this work the potential of the Digital Image-Based Flame Emission Spectrometry (DIB-FES) is demonstrated through two completely separate applications. The first one consists in the indirect determination of three drugs in injectable form: sodium dicofenac, sodium dipyrone and clacium gluconate and the second in the combination of DIB-FES with Multiple Linear Regression (MLR) for the simultaneous determination of sodium and calcium in powder milk. Up to the present moment the literature does not report the use of traditional FES in: indirect determination of organic substances, simultaneous determination of analytes using a unique detector and overcoming the problem of spectral interference. In DIB-FES digital images of the flame are captured by webcam in its oxidant region (2,5 cm over the burner of the flame photometer) and are associated with the radiation emitted by metals present in the air-butane flame. Based on Red-Green-Blue (RGB) colour system, univariate and multivariate calibration models were developed, which were validated and then applied to real samples. In each application the results were compared with the results obtained by their respective reference methods. There were no statistically significant differences between the results when the paired t-test at the 95% confidence level. The estimated precision was better than the respective reference methods and accuracy was assessed by high values of bias and recovery rates between 97 and 104% in the two applications. / Neste trabalho a potencialidade da Espectrometria de Emissão em Chama Baseada em Imagens digitais (DIB-FES) é demonstrada por meio de duas aplicações completamente distintas. A primeira consiste na determinação indireta de três fármacos em soluções injetáveis: diclofenaco sódico, dipirona sódica e gluconato de cálcio e a segunda na combinação da DIB-FES com Regressão Linear Múltipla (MLR) para a determinação simultânea de sódio e cálcio em amostras de leite em pó. Até o presente momento a literatura não reporta a utilização da FES tradicional na: determinação indireta de substâncias orgânicas, determinação simultânea de analitos utilizando um único detector e superação do problema de interferência espectral. Na DIB-FES as imagens digitais da chama são capturadas pela webcam na região oxidante da mesma (2,5 cm acima do queimador do fotômetro) e estão associadas às radiações emitidas pelos metais presentes na chama ar-butano. Com base no sistema de cores Vermelho-Verde-Azul (RGB) foram desenvolvidos modelos de calibração univariada e multivariada, os quais foram validados e então aplicados em amostras reais. Em cada aplicação os resultados obtidos foram comparados com os resultados obtidos por seus respectivos métodos de referência. Não houve diferenças estatisticamente significativas entre resultados ao aplicar o teste t emparelhado ao nível de 95% de confiança. A precisão estimada foi melhor do que a de seus respectivos métodos de referência e a exatidão foi verificada por altas taxas de tendência e fatores de recuperação entre 97 e 104% nas duas aplicações.

O objetivo deste estudo foi avaliar parâmetros tais como, moagem, tamanho de partículas, homogeneidade, segregação, dissolução de amostras e amostragem de suspensão, visando o desenvolvimento de método para a determinação de Ir, Pd, Pt e Rh por espectrometria de emissão óptica com plasma indutivamente acoplado (ICP OES) em sílica mesoporosa para uso catalítico. Após a moagem em moinho eletrônico de almofariz e pistilo, a análise do tamanho e distribuição das partículas revelou que 89% das partículas apresentam tamanhos <100 &#181;m e 23% com tamanho <5 &#181;m. Na avaliação de segregação dos analitos na amostra, os resultados obtidos para amostra com moagem grosseira, indicaram que os elementos estão distribuídos de maneira heterogênea entre as frações. Entretanto, a moagem fina aumentou a homogeneidade e esta pode ser uma etapa importante e necessária no sentido de evitar segregação da amostra. A análise por difração e de Raios-X mostrou que não ocorreram reações mecanoquímicas durante a moagem e por fluorescência de Raios-X forneceu resultados discrepantes entre os laboratórios, o pode estar relacionado com a heterogeneidade que induziu erros de amostragem. A avaliação de desempenho do ICP OES foi feita a partir do estabelecimento de parâmetros de mérito como seletividade, repetibilidade, estabilidade, robutez e limite de detecção. Na otimização foram considerados os parâmetros potência, vazão de nebulização e vazão de gás auxiliar. Foi feito um estudo em solução aquosa e em meio da amostra para escolha das linhas de emissão dos elementos Ir, Pd, Pt, Rh e dos candidatos a padrões internos. Apesar dos bons resultados encontrados em solução aquosa, o aumento do sinal de fundo em meio da amostra restringiu a escolha dos comprimentos de onda. Para o estudo da dissolução das amostras foram avaliados quatro procedimentos em forno de micro-ondas com frasco fechado. Os melhores resultados foram obtidos com 150 mg de amostra, 6 mL de água régia e 210 ºC de aquecimento durante 60 min. As determinações por ICP OES usando padrões internos Ru para Pd, Yb para Pt e Dy para Rh foram aquelas que forneceram os resultados mais coerentes com aqueles obtidos por fluorescência de Raios-X. Nos estudos visando à introdução de amostra na forma de suspensão foram avaliados: a massa de amostra para o preparo da suspensão, o efeito da concentração de ácido nítrico e o uso de padrão interno na tentativa de corrigir erros de matriz. 60 mg de amostra com um volume final de 20 mL de ácido nítrico 0,5% (v v-1) foram os escolhidos. Entretanto, a determinação dos elementos via suspensão mostrou resultados muito inferiores aos valores de concentrações esperados. Irídio foi investigado somente para otimização de ICP OES porque a sílica mesoporosa para uso de catalisador automotivo tem não esse elemento em sua composição. / The aim of this study was to evaluate parameters such as grinding, particle size, homogeneity, segregation, sample dissolution and slurry sampling for method development for the determination of Ir, Pd, Pt and Rh in silica mesoporosa for catalyst using inductively coupled plasma optical emission spectrometry (ICP OES). After the grind in an electronic grider with mill and pistil, the analysis of the particle size distribution showed 89% of particles with sizes <100 &#181;m and 23% of particles with sizes <5&#181;m. The separation in different particle size fractions showed that the sample with coarse grind (as sent to the lab) is not homogenous for the elements in comparison with that submitted to grind. X-Ray Diffraction and X-Ray Fluorescence analysis did not showed chemical reactions during the grinding, however a discrepancy between results of different laboratories. The performance of ICP OES was made by using figures of merit such as selectivity, repeatability, stability, robustness and limit of detection. In the optimization of ICP OES power supply, nebulizer flow rate and auxiliary gas flow rate were considered. Studies were conducted in aqueous and in the sample solution to choose emission wavelengths for Ir, Pd, Pt, Rh and internal standard candidates. Despite the good results obtained in aqueous solution, increasing the background signal in sample media restricted the choice of the emission wavelengths. For sample dissolution four procedures using microwave oven with closed-vessel were evaluated. The best results were obtained with 150 mg of the sample, 6 mL of aqua-regia and 210 ºC of heating, during 60 min. Determinations by ICP OES using internal standards Ru for Pd, Yb for Pt, and Dy for Rh were those who provided more consistent results in comparison with those obtained by x-ray fluorescence. For slurry sampling introduction sush parameters were evaluated: the mass of sample to prepare the slurry, the effect of the nitric acid concentration and the use of internal standard to correct matrix effects. 60 mg of the sample with a final volume of 20 mL of nitric acid 0.5% (v v-1) were chosen. However, the determination of Pd, Pt and Rh via suspension showed concentrations below to those expected, as determined by ICP OES in solution. Iridium was investigated only for ICP OES optimization because the silica mesoporosa for automobile catalyst use have not this element in its composition.

Dependence of glutathione concentration on the amount of thallium in the plant was studied. Observed plant was maize (Zea mays) which was divided to two parts – root and overground. Two culture procedures were elaborated where seeds and young seedlings were cultivated in a solution of thallium of concentration 0, 1, 3, 5, 8, a 10 µmol/l. Extraction agents used during extraction were phosphate buffer and solution of ascorbic acid. Determination of glutathione was realized by capillary electrophoresis (CE) and high performance liquid chromatography (HPLC). Diode array detector (DAD) was used in both methods. Quantification of the thallium amount in the plant was done by method of inductively coupled plasma-atomic emission spectrometry (ICP-AES).

This work deals with elemental analysis of inorganic materials, that are presented by blast furnace slag and geopolymeric material containing fly-ashes. In the theoretical part there are explained principles of elemental analysis of inorganic materials. Ways of dissolution of samples, optical emission spectroscopy and electron microscopy with energy dispersive x-ray analysis are commented. In experimental part the ICP analysis of oxide standards is described. The standards were used for estimation of EDS-correction factors. Then follow the preparation, proving and use of standards in analysis of blast furnace slag. The work is finished by exact analysis of concentration profiles of elements in interface of phases in geopolymeric material.

This article describes the compositional depth profiling (CDP) of diamond-like carbon (DLC) layers by Glow Discharge-Optical Emission Spectrometry (GD-OES). The DLC layers were deposited on flat steel samples. Analysis by using a Charge Coupled Device (CCD) GD-OES instrument revealed saturation effects of the carbon lines at 156 nm and 165 nm. Therefore, the application of these lines for CDP of DLC layers is not possible. A third line at 193 nm was not affected by this saturation effect and is therefore a good choice for calibration. A second effect was observed as a non-flat crater in combination with large differences of the sputtering rate factor of the substrate (1.1) and the DLC (0.032) led to an unusual behaviour at the interface between the DLC layer and substrate. Both measurements of the crater shape and of the sputtered coating weight up to the interface and just behind it showed clearly that about 30% of the DLC layer remains at the crater edge, once the crater centre reaches the interface. This was found to be the main reason for the incorrect DLC-layer thickness, if the intersection between the carbon and iron concentration was used as a measure for the end of the DLC layer.

The electrical properties, in particular the U–I characteristics, current and voltage signal shapes within the pulse, are important parameters for the understanding of the processes taking place in the pulsed glow discharge (PGD). The electrical properties are also closely related to the analytical performance of the PGD such as sputtering rates, crater shapes and emission yields. Moreover, the dependence of the U–I plots on the density of the discharge gas can be used to estimate the gas temperature. This result is relevant for the analysis of thermally fragile samples. Nevertheless, there is a lack of PGD studies where the current and voltage signals are considered in detail. Therefore, this article is dedicated to the electrical properties of PGD. The influence of the PGD parameters (duty cycle and pulse duration) on the electrical properties is examined. The results highlight the optimum parameters for particular analytical applications. The question, whether direct current (dc) and radio frequency (rf) discharges behave similarly is also discussed and all experiments are performed for both modes. The comparative studies reveal strong similarities between dc and rf pulsed discharges. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

Glow Discharge Optical Emission Spectrometry (GD OES) has proved to be a versatile analytical technique for the direct analysis of solid samples. The application of a pulsed power supply to the glow discharge (GD) has a number of advantages in comparison with a continuous one and thereby broadens the analytical potential of the GD. However, because the pulsed GD (PGD) is a relatively new operation mode, the pulsing and plasma parameters as well as their influence on the analytical performance of the GD are not yet comprehensively studied. The aim of this dissertation consists in the investigation of the PGD features, which are crucial for both understanding the discharge plasma processes and analytical applications. The influence of the pulsing parameters on the PGD is ascertained and compared for direct current (dc) and radio frequency (rf) discharges. In the research attention is firstly paid on the electrical parameters of PGD, then on the sputtered crater shapes, sputtering rates and finally on the light emission. It is found that the sputtered crater shape is strongly affected by the duration of the applied pulses even when the duty cycle is fixed. The pulse length influences the intensity of the light emission as well (at constant duty cycle). Moreover this influence is different for emission lines of atoms and ions in the plasma. This phenomenon can be seen at the comparison of atomic and ionic lines of different elements. The voltage–current plots of the PGD are found to indicate heating of the discharge gas when operating at high duty cycles. Using this feature a new method for the estimation of the discharge gas temperature from the voltage-current characteristics of the PGD is developed. The calculated temperature values are compared with another temperature measurement technique. Different temperature estimation procedures have shown that the discharge gas temperature can be reduced by around 100 K when PGD is applied. The temperature measurements have also confirmed that the gas heating can be adjusted by variation of the pulsing parameters. The effect of sputtering on the Cu(In,Ga)Se2 (CIGSe) layer surface of the solar cells is described for the first time. SEM investigations of the CIGSe layer of the solar cells have shown that sputter induced effects can be reduced by variation of the pulsing parameters. With regard to the question whether dc and rf pulsed discharges behave similarly: nearly all phenomena found with dc discharges also appear in the rf case. Hence it is concluded that the pulsed rf and dc discharges are very similar in terms of the electrical properties, sputtered crater formation, light emission and temperature. It is concluded that matrix specific, as well as matrix independent quantification principles and the intensity correction developed by Arne Bengtson can be applied for the pulsed mode, if special conditions are fulfilled. CIGSe solar cell samples and thin layered electrode metallizations of SAW devices are measured and quantified with application of PGD. The proposed quantification procedures are performed at commercial GD OES devices and can be used for the analysis with application of pulsed rf discharge. The studies of the PGD performed in this dissertation are relevant for the application of the GD OES analysis in materials science. During the collaborative work with Helmholtz-Zentrum Berlin für Materialien und Energie and with the research group of Dr. Thomas Gemming at IFW Dresden the optimized pulsed GD OES measurements could be successfully applied at the investigation of thin film solar cells with CIGSe light absorbing layer and electrode matallizations of SAW devices. In case of solar cell samples pulsed GD OES depth profiling along with SIMS measurements reveal the role of the Al2O3 barrier layer in high efficiency solar cells consisting of a CIGSe/Mo/Al2O3/steel substrate layer stack (the barrier layer is to prevent the Fe diffusion into the CIGSe). The features of the CIGSe films growth are studied with help of pulsed GD OES and in situ synchrotron XRD measurements. The diffusion coefficient of Zn into the CuInS2 layer is determined for the first time from the measured GD OES depth profiles of the corresponding solar cell samples. In case of SAW samples, pulsed GD OES measurements helped to evaluate the different SAW electrode preparation procedures and to select the most suitable one. In addition pulsed GD OES depth profiling along with XPS, TEM-EDX and electrode lifetime measurements indicate the possible mechanism of power durability and lifetime improvement of the SAW devices when a small amount of Al is added to the Cu-based electrodes. / Die optische Glimmentladungsspektroskopie (engl. Glow Discharge Optical Emission Spectrometry - GD OES) hat sich als eine vielfältige und schnelle Methode für die direkte Analyse von festen Materialien erwiesen. Die Anwendung von gepulsten Glimmentladungen (GD) bietet eine Reihe von Vorteilen im Vergleich zu einer kontinuierlichen Entladung und erweitert dadurch das analytische Potential der Methode. Die praktische Anwendung von gepulsten GD erfordert jedoch ein tiefes Verständnis der Prozesse, die in der Entladung und im elektrischen System ablaufen. Der Einfluss der Puls- und Plasmaparameter auf die analytische Leistung der gepulsten GD ist bislang noch nicht umfassend erforscht worden. Die Zielstellung dieser Arbeit besteht in der Untersuchung der Eigenschaften der gepulsten GD, welche von besonderer Bedeutung sowohl für das Verständnis des Entladungsprozesses als auch für analytische Anwendungen ist. Die Auswirkungen der Pulsparameter auf die gepulste GD wurde für den Gleichstrom-(DC) und Hochfrequenz- (HF) Modus untersucht und verglichen. Die Reihenfolge der Untersuchungen wurde in dieser Arbeit wie folgt gewählt: elektrische Parameter, Sputterkraterformen, Sputterraten und Lichtemission. Die Form des Sputterkraters korreliert stark mit der Pulsdauer, selbst wenn das Tastverhältnis konstant ist. Die Pulsdauer beeinflusst nicht nur die Kraterform, sondern auch die Intensität der Emissionslinien (bei konstantem Tastverhältnis). Darüber hinaus ist dieser Einfluss unterschiedlich für Atome und Ionen. Dieses Verhalten wurde an mehreren Emissionslinien (atomar bzw. ionisch) nachgewiesen. Aus der Analyse der U-I-Kennlinien der gepulsten GD ergab sich, dass es zu einer Erhitzung des Plasmas bei höherem Tastverhältnis kommt. Dieser Effekt wurde zur Bestimmung der Plasma-Gastemperatur ausgenutzt. Die ermittelten Temperaturen wurden mit einer andere Methode verglichen. Aus der Abschätzung ergab sich, dass die Plasmatemperatur bei gepulsten GD um bis zu 100 K gesenkt werden und durch die Pulsparameter genauer eingestellt werden kann. Der Einfluss des Sputterns auf Cu(In,Ga)Se2 (CIGSe) Dünnschichten von Solarzellen wurde erstmals beschrieben. REM-Untersuchungen an GD-gesputterten CIGSe Schichten haben gezeigt, dass die Sputtereffekte durch die Variation der Pulsparameter reduziert werden können. Es konnte gezeigt werden, dass HF- und DC-Entladungen dieselben Effekte aufweisen und sich nur geringfügig voneinander unterscheiden. Daraus kann geschlussfolgert werden, dass DC- und HF-Entladungen in Bezug auf elektrische Eigenschaften, Kraterformen, Lichtemission und Temperatur sehr ähnlich sind. Die Quantifizierung der mit gepulsten GD gemessenen Tiefenprofile ergab ferner, dass die Anwendung der Quantifizierungsmethoden für den kontinuierlichen Modus unter den gegebenen Bedingungen zulässig ist. Die Tiefenprofile von Solarzellen-Schichten sowie SAW-Metallisierungen wurden anhand gepulster GD gemessen und quantifiziert. Die empfohlenen Quantifizierungsmethoden können mit kommerziellen GD OES-Geräten durchgeführt werden. Die Untersuchungen an gepulsten GD sind insbesondere relevant für GD OES-Anwendungen im Bereich der Werkstoffwissenschaft. Während der Zusammenarbeit mit dem Helmholtz-Zentrum Berlin für Materialien und Energie und der Arbeitsgruppe von Dr. Thomas Gemming (IFW Dresden) konnten optimierte, gepulste GD OES Messungen erfolgreich zur Untersuchung von Dünnschicht-Solarzellen bzw. hochleistungsbeständigen SAW-Metallisierungen angewendet werden. Für die Solarzellen haben GD OES und SIMS Messungen geholfen, die Rolle der Al2O3-Barriere in CIGSe/Mo/Al2O3 Schichtstapeln auf flexiblem Stahlsubstrat besser zu verstehen (Al2O3 soll die Diffusion der Fe-Atome in CIGSe verhindern). Die gemeinsame Untersuchung getemperter CIGSe-Schichten mit gepulster GD OES und in-situ Synchrotron-XRD ergab neue Erkenntnisse zum Schichtwachstum. Der Diffusionskoeffizient von Zn in CuInS2 wurde erstmals aus GD OES-Tiefenprofilen bestimmt. Im Fall der SAW-Metallisierungen konnte die GD OES zur Bestimmung des geeignetsten Herstellungsverfahrens einen wichtigen Beitrag leisten. Die gepulste GD OES hat neben anderen Untersuchungsmethoden wie TEM-EDX, XPS und Lebensdauermessungen die Verbesserung der Leistungsbeständigkeit von Cu-Metallisierungen durch geringen Al-Zusatz aufklären können.