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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
81

X-ray Study of Strain, Composition, Elastic energy ans Atomic ordering in Ge islands on Si(001)

Malachias, Angelo 19 July 2005 (has links) (PDF)
Neste trabalho foram utilizadas técnicas de difração de raios-x para estudar propriedades químicas e estruturais de ilhas de Ge:Si(001). Através de experimentos de difração por incidência rasante foi realizado um mapeamento estrutural da relaxação de strain dentro de pirâmides e domos de Ge. Alterando-se a energia dos raios-x próximo à borda K do Ge – em medidas de difração anômala – foi possível determinar a composição química dos dois tipos de ilhas. A energia elástica, obtida correlacionando-se estes dois resultados, provou ser um dos fatores responsáveis pelas transições morfológicas neste sistema. Uma extensão dos resultados, com o uso de um novo método de análise, permitiu um completo mapeamento tri-dimensional da estrutura e estequiometria dos domos de Ge. Por último, foi observada a existência de uma liga ordenada de SiGe dentro dos domos, indicando o importante papel da cinética de crescimento na incorporação de Si nas ilhas.
82

In-situ Untersuchungen zur Entstehung von Oberflächengittern in Polymeren

Henneberg, Oliver January 2004 (has links)
In festen azobenzenhaltigen Polymeren wurde bei Bestrahlung mit blauem Licht ein makroskopischer Materialtransport beobachtet. Um die Dynamik der Gitterentstehung zu verfolgen, wurde am Speicherring für Synchrotronstrahlung ein Gitterschreibaufbau errichtet. Damit konnte erstmals in dieser Arbeit die Gitterbildungsgeschwindigkeit in-situ simultan mit Röntgen- und Lichtstreuung untersucht werden. Mit Hilfe einer speziellen Anpassung der Röntgenstreutheorie konnten sehr gute Übereinstimmungen von theoretischen Berechnungen mit den Messergebnissen erzielt werden. Dabei konnte nachgewiesen werden, dass sich zeitgleich mit einem Oberflächengitter auch ein Dichtegitter entwickelt. Durch die Trennung beider Streuanteile ließ sich die Dynamik der Strukturentstehungen bestimmen. Des weiteren konnte erstmals mit Hilfe der Photoelektronenspektroskopie die molekulare Orientierung an der Oberfläche eines Oberflächengitters nachgewiesen werden. Die Bewegungsursache kann auf einen Impulsübertrag während der Isomerisierung zurückgeführt werden, während die Bewegungsrichtung durch den elektrischen Feldvektor festgelegt wird. Die Theorie der Gitterentstehung konnte verbessert werden. / Solid azobenzene containing polymers show a macroscopic material transport under illumination with blue light. A writing setup was constructed at a synchrotron beamline in order to investigate the dynamics of the grating formation. With this setup it was possible to record the grating velocity for the first time simultaneously with x-ray and laser light scattering. <br /> A very good consistency could be achieved between the experiments and a suitable accomodation of the x-ray scattering theory. The theory reveals, that a density grating develops simultaneously with a surface grating. By separation of both parts the dynamics was determined for the density and the surface grating.<br /> The molecular ordering was determined at the surface with photoelectron spectroscopy. A momentum transfer could be identified as the source of the movement while the electric field defines the direction of the movement. The theory of the grating formation was improved.
83

The Controlled Drift Detector As An X-ray Imaging Device For Diffraction Enhanced Imaging

Ozkan, Cigdem 01 February 2009 (has links) (PDF)
Diffraction Enhanced Imaging (DEI) is an X-ray imaging technique providing specific information about the molecular structure of a tissue by means of coherently scattered photons. A Controlled Drift Detector (CDD) is a novel 2D silicon imager developed to be used in X-ray imaging techniques. In this work a final (complete and detailed) analysis of DEI data taken with the CDD in the ELETTRA synchrotron light source facility in Trieste (Italy) in 2005, is presented and the applicability of both this new technique and the novel detector are discussed.
84

Molecular speciation of phosphorus in organic amendments and amended soils using nuclear magnetic resonance and X-ray absorption spectroscopies

Ajiboye, Babasola 14 September 2007 (has links)
Characterization of phosphorus (P) in organic amendments is essential for environmentally sustainable fertilization of agricultural soils. The sequential chemical extraction (SCE) technique commonly used for P characterization does not provide any direct molecular information about P species. Studies were conducted to characterize P species in organic amendments and amended soils at a molecular level. The SCE was used to fractionate P in organic amendments including biosolids, hog, dairy and beef cattle manures, and poultry litter. The extracts were analyzed for total P and P species using inductively coupled plasma - optical emission spectroscopy (ICP-OES) and solution 31P nuclear magnetic resonance (NMR) spectroscopy, respectively. The relative proportions of P species in intact organic amendments and residues after each extraction, and calcareous soils amended with organic amendments and monoammonium phosphate (MAP) were estimated using the synchrotron-based P 1s X-ray absorption near edge structure (XANES) spectroscopy. The solution 31P NMR provided a detailed characterization of organic P in the non-labile NaOH and HCl fractions of organic amendments, but was limited in characterizing the labile fractions of most of these organic amendments due to their proneness to alkaline hydrolysis. The XANES analysis, however, identified the actual chemical species constituting the labile P that was only characterized as inorganic P or orthophosphates by sequential extraction and solution 31P NMR. In the amended Vertisolic and Chernozemic soils, XANES analysis estimated ‘soluble and adsorbed P’ as the dominant P species. For the Vertisolic soil, both the unamended and soil amended with biosolids and MAP contained hydroxyapatite (HAP). In addition, soil amended with biosolids, hog and dairy manures contained β-tricalcium phosphate (TRICAL), a more soluble CaP than HAP. TRICAL was found in all amended soils except in that amended with hog manure, while HAP was present in appreciable amount only in the control. Overall, the combination of techniques used in these studies improved the understanding of P species in organic amendments and amended soils that would not have been possible with any individual technique. Technological advances in P analysis should therefore be combined with conventional chemical extraction techniques to determine the fate of P in the environment.
85

Molecular speciation of phosphorus in organic amendments and amended soils using nuclear magnetic resonance and X-ray absorption spectroscopies

Ajiboye, Babasola 14 September 2007 (has links)
Characterization of phosphorus (P) in organic amendments is essential for environmentally sustainable fertilization of agricultural soils. The sequential chemical extraction (SCE) technique commonly used for P characterization does not provide any direct molecular information about P species. Studies were conducted to characterize P species in organic amendments and amended soils at a molecular level. The SCE was used to fractionate P in organic amendments including biosolids, hog, dairy and beef cattle manures, and poultry litter. The extracts were analyzed for total P and P species using inductively coupled plasma - optical emission spectroscopy (ICP-OES) and solution 31P nuclear magnetic resonance (NMR) spectroscopy, respectively. The relative proportions of P species in intact organic amendments and residues after each extraction, and calcareous soils amended with organic amendments and monoammonium phosphate (MAP) were estimated using the synchrotron-based P 1s X-ray absorption near edge structure (XANES) spectroscopy. The solution 31P NMR provided a detailed characterization of organic P in the non-labile NaOH and HCl fractions of organic amendments, but was limited in characterizing the labile fractions of most of these organic amendments due to their proneness to alkaline hydrolysis. The XANES analysis, however, identified the actual chemical species constituting the labile P that was only characterized as inorganic P or orthophosphates by sequential extraction and solution 31P NMR. In the amended Vertisolic and Chernozemic soils, XANES analysis estimated ‘soluble and adsorbed P’ as the dominant P species. For the Vertisolic soil, both the unamended and soil amended with biosolids and MAP contained hydroxyapatite (HAP). In addition, soil amended with biosolids, hog and dairy manures contained β-tricalcium phosphate (TRICAL), a more soluble CaP than HAP. TRICAL was found in all amended soils except in that amended with hog manure, while HAP was present in appreciable amount only in the control. Overall, the combination of techniques used in these studies improved the understanding of P species in organic amendments and amended soils that would not have been possible with any individual technique. Technological advances in P analysis should therefore be combined with conventional chemical extraction techniques to determine the fate of P in the environment.
86

Equilibrium and metastable solidification in Ti-Al-Nb and Al-Ni systems

Shuleshova, Olga 28 June 2010 (has links) (PDF)
The presented work reports on the solidification studies in two alloy systems: the niobium bearing γ-TiAl, relevant for the automotive and aero-engine applications, and aluminium rich Raney-Ni, precursor alloys for catalyses used in the chemical industry. The time-resolved observations of equilibrium liquid-solid phase transformations, as well as non-equilibrium solidification from the undercooled melt, are performed by combination of in situ structural studies using high-energy X-rays at a synchrotron source and the electromagnetic levitation technique. Containerless processing assured the contamination-free environment leading to high undercooling levels even at moderate cooling rates. For the critical part of the Ti-Al-Nb phase diagram an equilibrium involving the liquid phase is deduced from the phase transformations gathered on heating periods of levitation experiment. New experimental data on the partial liquidus and solidus surfaces are delivered as well as the information on the nature of the reactions along the univariant lines. These data provide a valuable contribution to the reassessment of the thermodynamic description. The primary phase selection as function of undercooling is studied in ternary Ti-Al-Nb alloys. The metastable formation of the cubic β phase within the primary solidification region of the hexagonal α phase is observed with increasing melt undercooling. Furthermore, the microstructure evolution of the β solidifying Ti-46Al-8Nb alloy discloses the transition to the thermal growth mode for ∆T>200−250 K, accompanied by complete solute trapping. Supplemented with the data on the solidification velocity determined as function of melt undercooling, this results are discussed within the local non-equilibrium model of the free dendrite growth. The in situ observations of the non-equilibrium solidification of the binary Al-Ni system give insight into multiple phase transformation sequence. The achieved undercooling levels up to 320 K for the aluminium alloys containing 18–31.5 at.% Ni did not alter the primary phase selection. However, during further cooling of L+Al3Ni2 semisolid samples the peritectic formation of a metastable decagonal quasicrystalline phase is observed providing a critical undercooling below the peritectic temperature of Al3Ni phase is reached. On further cooling the metastable phase subsequently transforms into the equilibrium Al3Ni. A similar solidification pathways are expected for the Raney-Ni alloys produced by gas atomisation, where the associated high cooling rates allowed to retain the metastable phase at room temperature.
87

Measurements of diffuse galactic emission at 5 GHz with C-BASS

Jew, Luke January 2017 (has links)
The C-Band All-Sky Survey (C-BASS) is a project to produce an all-sky map in intensity and polarization at a central frequency of 5 GHz with 1 GHz bandwidth and approximately 1 degree resolution. The central frequency is low enough for the map to be dominated by synchrotron and free-free emission but high enough so that Faraday rotation and depolarization are small across most of the sky. The C-BASS map will enable a more accurate removal of contaminating foregrounds from measurements of the cosmic microwave background, particularly in polarization where the B-mode signal from inflation is likely to be orders of magnitude weaker than the diffuse Galactic foreground emission. To produce an all-sky map from the ground requires two telescopes, one in the northern and one in the southern hemisphere. This thesis focuses on analysis of C-BASS North data. The noise properties of time-ordered data are characterised by fitting a noise model to periodograms. Using simulations, the errors introduced into the C-BASS maps by a destriping mapmaker are quantified and we reduce the signal error by masking the brightest pixels during baseline offset estimation. Jackknife tests are used to test the C-BASS data for systematics and to test the accuracy of the sensitivity maps. In total intensity, the spectral index of diffuse Galactic emission between 5 GHz and 408 MHz is measured using an extended T-T plot method and the results are compared to simulations. The spectral index of polarized diffuse Galactic emission between 5 GHz and 30 GHz is estimated in 55 arcminute pixels, modelling the polarized intensity as a Rician random variable.
88

Optique statistique pour l'émission synchrotron : calcul numérique en modes de cohérence / Statistical optics for synchrotron emission : numerical calculation of coherent modes

Glass, Mark 21 June 2017 (has links)
Le contexte de cette thèse est l'étude de la cohérence partielle dans les faisceaux synchrotron produits par les anneaux de stockage de basse émittance, comme l’ESRF-EBS. L'objectif principal est la compréhension et l'application de la physique sous-jacente pour l'implémentation et le développement d'outils de calcul.Nous développons d’abord une théorie de l'optique-statistique pour les radiations émisses par des anneaux de stockage qui est basée sur le théorème de Kim et sur les contributions de Geloni et al. Nous utilisons ces formules d'une manière détaillée et légèrement différente. Nous insistons sur l'importance des paramètres stochastiques des faisceaux d'électrons pour décrire les propriétés de cohérence. Nous observerons que la longueur du paquet des électrons n’affecte pas les propriétés de la cohérence s’il y a un couplage faible entre la position longitudinal de l’électron et ses autres paramètres.Nous avons construit une description de l'optique statistique pour l’émission synchrotron liée aux modes de cohérence. Nous voyons qu'un ensemble est complètement cohérent si et seulement si ses modes de cohérences se réduisent a un seul mode. Geloni et al. mentionnent que l’émission d’un synchrotron est un processus stochastique gaussien. Nous ajoutons qu’il a une moyenne nulle et il est symétrique circulaire. En conséquence nous pouvons donner une interprétation physique au degré de cohérence spectrale en termes de densité de probabilité conditionnée de forme gaussienne.Nous avons développé et implémenté un algorithme qui calcule la décomposition de la densité spectrale en modes de cohérences. Il peut être appliqué à un faisceau d'électrons avec un paramètre Twiss-alpha fini et une dispersion d’énergie. Nous avons implémenté deux versions de l'algorithme. La première résout l'équation de Fredholm dans une base de fonctions constantes par morceaux. Les calculs pour les hautes harmoniques d'un onduleur et pour des émittances relativement larges demandent une trop grande mémoire pour être calculées. Pour réduire la mémoire requise, nous avons développé une méthode en deux pas. On résout d'abord l'équation pour un faisceau d'électron de divergence nulle, puis on ajoute les effets de la divergence dans un second temps.Nous présentons des tests approfondis qui incluent une distribution des électrons du type fonction delta, des champs électriques gaussiens dont les résultats analytiques sont connus, ainsi qu'une comparaison avec des résultats Monte Carlo produits par SRW.Nous appliquons cet algorithme sur un nombre de cas particuliers. Nous déterminons combien de modes sont nécessaires pour inclure 95% de la densité spectrale et comment le degré de cohérence spectrale change. Nous trouvons que la dispersion d'énergie ajoute des modes de cohérence. Cet effet est négligeable pour des anneaux courants mais pour l’ESRF-EBS elle ajoute des nouveaux modes. Des onduleurs plus courts et des plus hautes harmoniques augmentent le nombre de modes. Une comparaison entre un onduleur placée dans un point avec alpha fini et dans un point symétrique ne montre pas de différences significative. Une réduction artificielle de l’émittance du anneau ESRF-EBS montre un décroit du nombre de mode jusqu’à arriver à un seul mode.Nous avons simulé une ligne de lumière simplifiée focalisant 1:1. Une réduction de la taille de l'ouverture change les valeurs propres du spectre vers des modes de plus en plus petits ce qui entraine aussi une réduction du flux. Nous présentons une comparaison entre la densité spectrale calculée avec l’approximation Gauss-Shell, l’approximation analytique et l’approximation de la séparation. Bien qu'il n'y a pas d'erreurs négligeables entre le calcul exact et l'approximation de la séparation, nous concluons que cette dernière peut être une bonne et rapide solution permettant des calculs sur des ordinateur portables.Nous terminons cette thèse par une discussion/des idées sur de futures recherches. / The context of this thesis is the study of the partial coherence in synchrotron beams produced by ultra low emittance storage rings, like the ESRF-EBS ring under construction. As main objectives we had the understanding, application and development of the underlying physics and the implementation of computer tools able to calculate the relevant parameters.In the first part of this thesis we develop a theory for statistical optics for storage ring radiation. It is based on the brightness convolution theorem by Kim and on the subtle but very important theoretical contributions from Geloni et al. We derive their formulas in a slightly different way or in more a detailed form.We emphasize the importance of the description of the electron beam stochastic for the coherence properties of storage ring emission. We observe that for weak coupling of the longitudinal electron position to the other beam parameters the bunch length is a free parameter in view of coherence properties.We build our description of statistical optics around coherent modes. We show that an ensemble is completely coherent if and only if its coherent mode decomposition is a single mode. Geloni et al. mentioned that the synchrotron storage ring emission is a Gaussian random process. We add that the process has zero mean and is circularly-symmetric. In consequence we can give the spectral degree of coherence a physical interpretation in terms of Gaussian shaped conditional probability densities.We developed and implemented an algorithm that calculates the coherent mode decomposition of the cross spectral density for a given wavelength. It can be applied to electron beams with finite Twiss alpha and with energy spread. We implemented two algorithms. The first version solves the Fredholm equation in a two-dimensional step function basis set. Because of its memory requirements high undulator harmonics or current lattices with high emittances cannot be calculated. To reduce the memory requirements we developed the two-step method that solves the problem first for an electron beam with zero divergence and adds the effects of the divergence in a second step. The algorithms use the eigensolver library SLEPc. The implementations of the algorithms are open source.We present extensive tests of the algorithms. They include a delta-function shaped electron beam, a Gaussian single electron reference electric field, whose results are analytically known, and comparisons to SRW Monte Carlo samplings.We apply the algorithm to some particular cases. We determine how many modes are necessary to incorporate 95% of the spectral density and how the spectral degree of coherence changes. We find that the energy spread adds extra coherent modes. This effect is negligible for current lattices but for the ESRF-EBS lattice it accounts for a significant fraction of the total modes. Shorter undulators and higher harmonics increase the number of modes. A comparison between an undulator placed at a point with finite alpha and at a symmetry point shows no significant differences. A reduction of the ESRF-EBS beam parameters show a decrease of the mode numbers until they reach a single mode. We simulate a simple 1:1 imaging beamline with an aperture in the image plane. A reduction of the aperture size changes the eigenvalue spectrum to fewer and fewer modes that is paid with a decrease of flux. We present a comparison of the calculated cross spectral density with a Gaussian Schell-model, an analytic approximation and a separation approximation. Although there are not negligible errors between the exact calculation and the separation approximation we come to the conclusions that the separation approximation might be a good and quick approximation that allows the calculation on portable computers.We end the thesis with some ideas for future research.
89

Mapeamento multielementar de úlceras induzidas utilizando fluorescência de raios X

Vieira, Letícia Diniz January 2018 (has links)
Orientador: Joel Mesa Hormaza / Resumo: A úlcera péptica é provocada pelo desequilíbrio entre fatores lesivos e protetores das mucosas gástrica e duodenal, em consequência a fatores endógenos ou exógenos aos tecidos. Para seu tratamento, algumas plantas são popularmente empregadas e demonstram eficácia semelhante ou superior aos fármacos geralmente utilizados, ocasionando menores efeitos adversos. Apesar de várias pesquisas na área, a compreensão do mecanismo gastroprotetor dos compostos fitoterápicos ainda não é completa. Assim, com o objetivo de contribuir para a compreensão da ação farmacológica dos extratos de três plantas medicinais (Alchornea glandulosa, Davilla elliptica e Davilla nitida), foi realizada uma análise da distribuição elementar dos constituintes das amostras de mucosas gástricas de ratos tratados com os extratos vegetais e que tiveram úlceras gástricas induzidas por álcool ou por droga anti-inflamatória não-esteroidal (DAINE). O experimento foi realizado no Laboratório Nacional de Luz Síncrotron (LNLS) e permitiu a análise dos elementos Cl, Ca, Mn, Fe, Cu e Zn que contem relação com a formação ou neutralização das úlceras pépticas. De acordo com os mapas da distribuição dos elementos, foi possível detectar alta concentração de Fe, Cu e Zn no interior da lesão das amostras de úlcera induzida por DAINE, e de Cu, Zn e Cl no interior da lesão das amostras induzidas por álcool. Nas amostras de úlcera induzida por DAINE e tratadas com Alchornea glandulosa, as concentrações de Ca, Cu e Fe aumentaram. N... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The peptic ulcer is caused by the imbalance between harmful and protective factors of the gastric and duodenal mucosa, as a consequence of factors endogenous or exogenous to the tissues. For its treatment, some plants are popularly employed and demonstrate efficacy akin or superior to the drugs normally used, leading to less adverse effects. Although much research has been conducted in the field, the understanding of the gastroprotective mechanism of phytotherapic compounds is still not complete. Therefore, aiming to advance the understanding of the pharmacological action of the extracts of three medicinal plants (Alchornea glandulosa, Davilla elliptica e Davilla nitida), we conducted an analysis of the elemental distribution of constituents within samples of gastric mucosa from rats treated with phytoterapic extracts and affected with peptic ulcers induced by alcohol or nonsteroidal anti-inflammatory drugs (NSAIDs). The experiment was performed at the Brazilian Synchrotron Light Laboratory (LNLS) and allowed for the analysis of the elements Cl, Ca, Mn, Fe, Cu and Zn that are connected to peptic ulcers development or inhibition. According to the elemental distribution maps, it was possible to detect high concentrations of Fe, Cu and Zn inside the lesion from the NSAID-induced ulcer samples, and of Cu, Zn and Cl inside the lesion from the alcohol-induced ulcer samples. In NSAID-induced ulcer samples treated with Alchornea glandulosa, Ca, Cu and Fe concentrations were augmented... (Complete abstract click electronic access below) / Doutor
90

Investigação da estrutura eletrônica e dinâmica de fotofragmentação da molécula Tiazol (C3H3NS)

Januário, Robin Dominicio January 2015 (has links)
Orientador: Prof. Dr. Alexsandre Figueiredo Lago / Dissertação (mestrado) - Universidade Federal do ABC. Programa de Pós-Graduação em Ciência e Tecnologia/Química, 2015. / Neste trabalho original, sao apresentados os resultados inetidos de estudos sobre excitacao eletronica, fotoionizacao e dissociacao ionica em fase gasosa para a molecula de Tiazol (C3H3NS). Esta molecula se destaca por suas diversas aplicacoes em quimica, bioquimica, astrofisica e na industria. Observamos a escassez de informacoes relevantes para este sistema molecular na literatura, envolvendo estudos espectroscopicos e espectrometricos em fase gasosa. Assim, os resultados obtidos neste trabalho, sao considerados inetidos para este sistema molecular. Para realizacao de tais estudos, utilizou-se tecnicas de espectrometria de massas por tempo de voo (TOF-MS) em conjunto com as tecnicas espectroscopicas de coincidencia fotoeletron-fotoion(PEPICO), fotoeletron-fotoion-fotoion (PEPIPICO), producao total e parcial de ions. Para a ionizacao da amostra, empregou-se a Luz Sincrotron na regiao do ultravioleta de vacuo (UVV) e Raios-X. Os experimentos foram conduzidos nas linhas de Luz TGM, SGM e SXS do Laboratorio Nacional de Luz Sincrotron (LNLS) em Campinas, SP. Na faixa de energia de 9 a 21 eV, da interacao do fotons com com a amostra em fase gasosa e o progresso resultante da abertura de canais de fragmentacao ionica molecular. Foram propostas rotas reacionais de fotoionizacao e dissociacao ionica para a molecula e fragmentos, e determinacao dos rendimentos parciais ionicos (PIY). Com o aumento gradual da energia de interacao novas rotas de dissociacao se tornam energeticamente favoraveis, resultando no aparecimento de fragmentos com menor relacao massa/carga; isto, devido ao favorecimento na quebra das ligacoes quimicas, possibilitando rotas de dissociacao diversas. As principais rotas reacionais bem como principais fragmentos em destaque sao: C3H3NS + hv ¨ C3H3NS+ + e-; C3H3NS + hv ¨ C2H2S+ + HCN + e-; C3H3NS + hv ¨ CH2N + C2HS+ + e-. Os resultados deste trabalho para nivel de valencia, foram publicados na revista Journal of Mass Spectrometry. Os estudos relativo as camadas internas da molecula tambem foram realizados, em regioes com energias mais altas dos fotons, na regiao de Raio-X. Foram medidos espectros de rendimento total de ions (TIY) em energias cobrindo as bordas (camadas internas) dos elementos C 1s, N 1s, S 2p e S 1s; a partir dai foram propostas as transicoes eletronicas mais provaveis, originadas entre o estado fundamentcomo na regiao de UVV, rendimentos ionicos parciais (PIY) foram determinados nos estudos de camadas internas, utilizando a tecnica PEPIPICO, determinou-se qualitativamente os pares de ions mais importantes observados em coincidencias multiplas de reacoes de fotodissociacao em cada uma das bordas de absorcao estudadas. Para auxiliar nos resultados experimentais, e com o objetivo de obter parametros como estrutura eletronica, geometria dos estados fundamentais da molecula proposta e dos correspondentes cations obtidos por ionizacao e dissociacao, foram realizados calculos de quimica teorica usando metodos ab initio, utilizando o pacote de softwares GaussianR. / In this original project are presented novel results for the study of the electronic excitation, photoionization and ionic dissociation for the thiazole molecule in gas phase .This molecule stands out for its variety of different applications in chemistry, biochemistry, astrophysics and industries. We have noted a lack of relevant informations to this molecular system in the literature, involving spectroscopic and spectrometric studies in gas phase. Therefore, the results obtained from this work may be considered important new contributions to the field. In order to perform realize these studies, it we have used a was used mass spectrometry of time-of- flight (TOF-MS) together with the electron-ion coincidence techniques PEPICO, PEPIPICO, as well as total and partial ion yield techniques. As the ionizing source, the Synchrotron Light was used in the vacuum ultraviolet region (UVV) and X-ray ranges. The experiments were conducted at the on beam lines TGM, SGM and SXS in from the Brazilian Synchrotron Light Facility (LNLS), located in Campinas, SP. In the VUV range from 9 to 21 eV, it was observed the influence of the photon interaction on the gas phase sample and resulting progress on the opening of the molecular fragmentation channels. Reactional routes for the photoionization and ionic dissociation processes for the molecule and its fragments have been proposed, and the partial ion yields (PIY) determined. With the gradual increase of the photon energy, additional ion dissociation channels are energetically favorable, inducing chemical bonds rupture, and resulting in the appearence of fragments with lower mass/charge ratio. The photodissociation reaction observed from our spectra , as well as, the main ionic fragments in bold are: C3H3NS + hv ¨ C3H3NS+ + e-; C3H3NS + hv ¨ C2H2S+ + HCN + e-; C3H3NS + hv ¨ CH2N + C2HS+ + e-. from the valence studies for thiazole molecule have been recently published in the Journal of Mass Spectrometry. Inner shells studies have also been performed for this molecule at higher photon energies, in the soft and tender X-ray domains. We have recorded total ion yield spectra (TIY) covering the C 1s, N 1s, S 2p and S 1s edges, and based on the spectra we proposed the most likely electronic transitions related to the inner shells processes.The main electronic transitions found were: S 2p ¨ ¿�, we were able to determine and discuss, qualitatively, the most important pairs of ions generated in multiple coincidences from photodissociations reactions for each of the absorption edges studied. Ab initio calculations have been made in order to assist with the experimental data analysis and also aiming to obtain additional parameters such as: electronic structure, molecular neutral, ion, and fragments geometric structures, ionization energies, and so on. The theoretical studies were performed by using the GaussianR packages.

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