19 resultados para negative-ion
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Review of scientific instruments, Vol.72, Nº9
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Dissertação para obtenção do Grau de Doutor em Engenharia Física
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Dissertação para obtenção do Grau de Doutor em Engenharia Física
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The role of a set of gases relevant within the context of biomolecules and technologically relevant molecules under the interaction of low-energy electrons was studied in an effort to contribute to the understanding of the underlying processes yielding negative ion formation. The results are relevant within the context of damage to living material exposed to energetic radiation, to the role of dopants in the ion-molecule chemistry processes, to Electron Beam Induced Deposition (EBID) and Ion Beam Induced Deposition (IBID) techniques. The research described in this thesis addresses dissociative electron attachment (DEA) and electron transfer studies involving experimental setups from the University of Innsbruck, Austria and Universidade Nova de Lisboa, Portugal, respectively. This thesis presents DEA studies, obtained by a double focusing mass spectrometer, of dimethyl disulphide (C2H6S2), two isomers, enflurane and isoflurane (C3F5Cl5) and two chlorinated ethanes, pentachloroethane (C2HCl5) and hexachloroethane (C2Cl6), along with quantum chemical calculations providing information on the molecular orbitals as well as thermochemical thresholds of anion formation for enflurane, isoflurane, pentachloroethane and hexachloroethane. The experiments represent the most accurate DEA studies to these molecules, with significant differences from previous work reported in the literature. As far as electron transfer studies are concerned, negative ion formation in collisions of neutral potassium atoms with N1 and N3 methylated pyrimidine molecules were obtained by time-of-flight mass spectrometry (TOF). The results obtained allowed to propose concerted mechanisms for site and bond selective excision of bonds.
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The Journal of Biological Chemistry Vol. 278, No. 19, Issue of May 9, pp. 17455–17465, 2003
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Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Mestre em Conservação e Restauro
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Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para a obtenção do grau de Mestre em Engenharia Biomédica
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Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Mestre em Computational Logic
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Dissertação para obtenção do Grau de Mestre em Biotecnologia
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Dissertação para obtenção do Grau de Doutor em Engenharia Química, especialidade de Engenharia Bioquímica
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J Biol Inorg Chem (2011) 16:51–61 DOI 10.1007/s00775-010-0700-8
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Dissertação para obtenção do Grau de Doutor em Engenharia Física
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A Work Project, presented as part of the requirements for the Award of a Masters Degree in Finance from the NOVA – School of Business and Economics
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Dissertation to obtain a Master degree in Biotechnology
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Dissertação para obtenção do Grau de Doutor em Química Sustentável