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No description available.

This thesis presents the study of a selection of gas phase chemical processes using time-resolved Fourier transform infrared (FTIR) emission spectroscopy. Such processes include molecular energy transfer, chemical reaction and photodissociation. The major focus of this thesis was the investigation of collisional energy transfer from the electronically excited states of NO and OH, with particular attention paid to the fate of the electronic energy. NO A²&Sigma;⁺(v = 0) is prepared by laser excitation, pumping the overlapped Q₁ and P₂₁ band heads of the NO A-X (0,0) transition at 226.257 nm. The quenching of this state by O₂ and CO₂ was studied. Experiments were performed to investigate what channels contribute to the quenching process, the branching ratio of these different channels and the partitioning of energy among the various products. Quenching by O₂ was found to proceed mostly through non-reactive channels. High vibrational excitation of NO X ²&Pi; was observed, with population detected in v = 22, representing 79% of the available energy. The O₂ product was found to be formed in more than one electronic state: the ground state, X ³&Sigma;^-<sub style='position: relative; left: -.3em;'>g</sub>, and a high-lying electronically excited state, such as the A ³&Sigma;⁺<sub style='position: relative; left: -.5em;'>u</sub>, A' ³&Delta;_u or c ¹&Sigma;^-<sub style='position: relative; left: -.5em;'>u</sub> states. A reactive channel producing vibrationally excited NO₂ was observed, but was found to be a minor process with an upper limit of 18% for the branching ratio. In contrast the quenching of NO A ²&Sigma;⁺(v = 0) by CO₂ was found to proceed predominately by reaction, with a branching ratio of 76 %. While emission from NO₂ was observed, it was weak, and therefore it was concluded that the main reaction products were CO, O(³P) and NO X ²&Pi;(v = 0). The nascent strong CO₂ v3 emission band from the non-reactive channel exhibited a large red-shift from its fundamental position. This indicates that the CO₂ vibrational distribution is significantly hotter than statistical. Investigations were then performed studying the quenching of NO A ²&Sigma;⁺(v = 1) by NO and CO₂, with both systems exhibiting similar characteristics to the quenching of the ground vibrational level of NO A ²&Sigma;⁺. From comparison of the emission intensity of the CO fundamental and CO₂ v3 mode following quenching of the v = 0 and 1 levels of the NO A ²&Sigma;⁺ state, it was concluded that the branching ratio for reactive quenching was larger in the latter case. Secondly, experiments were performed to measure the rate constants for the quenching of NO A ²&Sigma;⁺(v = 0) by the noble gases. The noble gases are inefficient quenchers of electronically excited NO and therefore careful experimental design was required to minimise the influence of impurities on the results. All the rate constants were found to be of the order of 10^-14 cm³ molecule^-1 s^-1. The value for Xe was 50 times smaller than reported previously in the literature. In light of this new measurement, a re-analysis of experiments, performed previously in the group, on the electronic quenching of NO A ²&Sigma;⁺(v = 0) by Xe was performed. A very hot vibrational distribution of NO X ²&Pi; was obtained. Next, the collisional quenching of OH A ²&Sigma;⁺(v = 0) by H₂ was investigated. OH radicals were generated in situ by the photolysis of HNO₃ at 193 nm, which were excited to the A ²&Sigma;⁺(v = 0) state on the overlapped Q₁(1) and P₂₁(1) rotational lines at 307.935 nm. Reactive quenching was found to be the major pathway, in agreement with the literature. Copious emission from vibrationally excited water was observed. Comparison of this emission with theoretical calculations revealed a hotter distribution than predicted. It was concluded that the energy channelled into the vibrational modes of H₂O is in excess of 60% of the available energy. Experiments performed with D₂ allowed the non-reactive channel to be studied; a cold vibrational distribution of the OH X ²&Pi; was observed. Finally the reaction between CN radicals and cyclohexane was studied. CN was generated by the photolysis of ICN at 266 nm. Prompt emission from HCN in the C-H stretching region was observed meaning the new bond was formed in a vibrationally excited state. Analysis of the emission revealed HCN was populated up to v3 = 2. Excellent agreement with the results of a theoretical study of the system was found.

O presente trabalho determinou a concentração dos metais zinco, manganês, cádmio, chumbo, níquel, cobre e cromo no efluente e solo de quatro colunas de latossolo indeformadas. Duas colunas foram contaminadas por pilhas do tipo zinco-carbono e duas colunas foram utilizadas como referência, além de pilhas isoladas, foram todas lixiviadas por uma solução \"água de chuva\" (HNO3 + H2SO4, pH 4,0). Os metais no efluente e no solo foram determinados pela técnica de ICP-OES. A avaliação do efluente e do solo das colunas contaminadas pelas pilhas mostrou um incremento das concentrações dos metais, principalmente de zinco, manganês e chumbo. A sequência das massas acumuladas dos metais no efluente e no solo da coluna contaminada apresentaram uma sequência semelhante a da lixiviação isolada da pilha (Zn > Mn > Pb > Cr > Cu > Ni > Cd), confirmando a influência da pilha nas concentrações dos metais no efluente e solo das colunas. Observou-se também que a contaminação de Zn e Mn tende a migrar da camada superior da coluna de solo para as camadas inferiores. O estudo mostrou que as pilhas podem causar uma contaminação significativa do solo para os metais Zn, Mn e Pb e possivelmente também para Cd. Esta contaminação do solo poderia vir a causar uma contaminação da água subterrânea para os metais Zn, Mn e Pb, dependo das características do perfil do solo. / The aim of the present study was to determine the concentration of Zn, Mn, Pb, Cd, Cu, Cr, and Ni in an oxisol column contaminated with zinc-carbon batteries. Two control and two contaminated columns, and batteries alone were leached for a periods of six months and one year with aqueous solution of HNO3 and H2SO4 (1:1, pH 4,0) to simulate rainwater. The metal concentrations in effluent and soil were measured by means of ICP-OES technique. Results from the contaminated column showed enhanced concentrations in both effluent and soil (mainly zinc, manganese and lead). In addition, the total amount of metals in effluent and soil showed similar sequence order as observed for batteries alone (Zn > Mn > Pb > Cr > Cu > Ni > Cd) indicating that batteries can be considered the main source of contamination. We also observed migration of Zn and Mn from the top to the lower layers of the soil columns. The study gives further evidence that batteries can significantly contaminate the soil with metals like Zn, Mn and Pb, and maybe Cd too. This soil contamination combined with the enhanced concentrations found in the effluent can point out a probable groundwater contamination.

O presente trabalho determinou a concentração dos metais zinco, manganês, cádmio, chumbo, níquel, cobre e cromo no efluente e solo de quatro colunas de latossolo indeformadas. Duas colunas foram contaminadas por pilhas do tipo zinco-carbono e duas colunas foram utilizadas como referência, além de pilhas isoladas, foram todas lixiviadas por uma solução \"água de chuva\" (HNO3 + H2SO4, pH 4,0). Os metais no efluente e no solo foram determinados pela técnica de ICP-OES. A avaliação do efluente e do solo das colunas contaminadas pelas pilhas mostrou um incremento das concentrações dos metais, principalmente de zinco, manganês e chumbo. A sequência das massas acumuladas dos metais no efluente e no solo da coluna contaminada apresentaram uma sequência semelhante a da lixiviação isolada da pilha (Zn > Mn > Pb > Cr > Cu > Ni > Cd), confirmando a influência da pilha nas concentrações dos metais no efluente e solo das colunas. Observou-se também que a contaminação de Zn e Mn tende a migrar da camada superior da coluna de solo para as camadas inferiores. O estudo mostrou que as pilhas podem causar uma contaminação significativa do solo para os metais Zn, Mn e Pb e possivelmente também para Cd. Esta contaminação do solo poderia vir a causar uma contaminação da água subterrânea para os metais Zn, Mn e Pb, dependo das características do perfil do solo. / The aim of the present study was to determine the concentration of Zn, Mn, Pb, Cd, Cu, Cr, and Ni in an oxisol column contaminated with zinc-carbon batteries. Two control and two contaminated columns, and batteries alone were leached for a periods of six months and one year with aqueous solution of HNO3 and H2SO4 (1:1, pH 4,0) to simulate rainwater. The metal concentrations in effluent and soil were measured by means of ICP-OES technique. Results from the contaminated column showed enhanced concentrations in both effluent and soil (mainly zinc, manganese and lead). In addition, the total amount of metals in effluent and soil showed similar sequence order as observed for batteries alone (Zn > Mn > Pb > Cr > Cu > Ni > Cd) indicating that batteries can be considered the main source of contamination. We also observed migration of Zn and Mn from the top to the lower layers of the soil columns. The study gives further evidence that batteries can significantly contaminate the soil with metals like Zn, Mn and Pb, and maybe Cd too. This soil contamination combined with the enhanced concentrations found in the effluent can point out a probable groundwater contamination.

<p>Izmereni su Stark-ovi pomeraji maksimuma 8 spektralnih linija neutralnog helijuma u gustoj niskotemperaturnoj plazmi impulsnog luka. Osobine izvora plazme, sem postizanja visoke elektronske koncentracije, obezbeđuju relativno jednostavan način određivanja Stark-ovog pomeraja. Izvr&scaron;ena je dijagnostika plazme, pri čemu je određena elektronska koncentracija u intervalu od (6.2 &minus; 70) &middot; 10²² m^&minus;3 i elektronska temperatura u intervalu (16400 &minus; 21400) K. Eksperimenatlne vrednosti Stark-ovih pomeraja upoređene su sa do sada objavljenim eksperimentalnim rezultatima kao i sa rezultatima teorijskih pristupa. Proveren je uticaj Debye-evog ekraniranja na pomeraj ovih linija. Dobijeni rezultati ukazuju na popravku Stark-ovog pomeraja uračunavanjem<br />uticaja Debye-evog ekraniranja, kao i potrebu korigovanja semiklasičnih teorijskih vrednosti elektronske sudarne polu-polu&scaron;irine i pomeraja.</p> / <p>The results of an experimental study of the Stark shifts AB of 8 neutral helium lines are presented. The plasma sour-ce was a linear pulsed arc with plasma electron&nbsp; density in the range (6.2 &minus; 70) &middot; 10 ²² m^&minus;3 and plasma temperature in the range (16400 &minus; 21400) K. Details of the experimental setup that enables a relatively quick&nbsp; Stark shift determination technique is presented. The results of these measurements are presented together with the corresponding plasma parameters and compared to other experimental and theoretical data. The influence of Debye shielding is carefully examined from the semiclassical point of view. The comparison of experimental&nbsp; results obtained in this work with the semiclassical results suggests that Debye shielding has an important role on higher electron densities. Also, based on all the available experimental data, appropriate correction factors are suggested for the semiclassical Stark shift calculations for the examined lines.</p>

<p>The spectroscopic, SEM and Raman measurements on carbon nanotubes under the exact conditions of which OES analysis were made showed that at<br /> a pressure of 400 Torr and a flow rate of 200 sccm, the quality and quantity of single-walled carbon nanotubes was the highest.</p>

No description available.

<p>The spectroscopic, SEM and Raman measurements on carbon nanotubes under the exact conditions of which OES analysis were made showed that at<br /> a pressure of 400 Torr and a flow rate of 200 sccm, the quality and quantity of single-walled carbon nanotubes was the highest.</p>

Made available in DSpace on 2014-12-17T14:06:48Z (GMT). No. of bitstreams: 1 JulioCPB.pdf: 2433728 bytes, checksum: 9509a2a35ebc0e4009df0a9bced418db (MD5) Previous issue date: 2007-11-14 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Plasma process like ionic nitriding and cathodic cage plasma nitriding are utilized in order to become hard surface of steels. The ionic nitriding is already accepted in the industry while cathodic cage plasma nitriding process is in industrial implementation stage. Those process depend of plasma parameters like electronic and ionic temperature (Te, Ti), species density (ne, ni) and of distribution function of these species. In the present work, the plasma used to those two processes has been observed through Optical Emission Spectroscopy OES technique in order to identify presents species in the treatment ambient and relatively quantify them. So plasma of typical mixtures like N2 H2 has been monitored through in order to study evolution of those species during the process. Moreover, it has been realized a systematic study about leaks, also thought OES, that accomplish the evolution of contaminant species arising because there is flux of atmosphere to inside nitriding chamber and in what conditions the species are sufficiently reduced. Finally, to describe the physic mechanism that acts on both coating techniques ionic nitriding and cathodic cage plasma nitriding / Processos a plasma como nitreta??o i?nica e nitrteta??o por gaiola cat?dica s?o utilizados para endurecimento de superf?cies de a?os. A nitreta??o i?nica sendo j? consolidada em aplica??es industriais enquanto que o processo por gaiola cat?dica ainda se encontra em est?gio de pesquisa. Esses processos dependem dos par?metros de plasma como temperatura eletr?nica e de ?ons (Te, Ti), densidade de esp?cies (ne, ni,) e da fun??o de distribui??o das mesmas. No presente trabalho, o plasma utilizado para esses dois processos foi diagnosticado utilizando a t?cnica de Espectroscopia de Emiss?o ?ptica EEO para identificar as esp?cies presentes no ambiente de tratamento e quantifica-las relativamente. Assim, plasma de mistura gasosa t?pica como N2 H2 foi monitorado, com o intuito de estudar a evolu??o dessas esp?cies durante o processo. Al?m disso, foi realizado um estudo sistem?tico, tamb?m atrav?s de EEO, que acompanha a evolu??o das esp?cies contaminantes surgidas em vazamentos de modo a buscar condi??es onde as mesmas s?o suficientemente reduzidas. Finalmente busca-se, atrav?s do diagn?stico de plasma por EEO, descrever o mecanismo f?sico de atua??o das duas t?cnicas de tratamento: nitreta??o i?nica e gaiola cat?dica