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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.
1

\"O Brasil precisa de você\": uma leitura da propaganda produzida pelo IPES a partir das bases biológicas do comportamento humano (1962 - 1964) / \"O Brasil precisa de você\": a reading of the propaganda produced by the Brazilian IPES from the biological bases of human behavior (1962- 1964)

Kaufmann, Celia Regina Justo 21 August 2017 (has links)
O presente trabalho propõe considerar no conjunto de modelos interpretativos da História os estudos realizados em neurociência e psicologia sobre as bases biológicas e psicossociais do comportamento humano. A psicologia cognitiva revolucionou o entendimento do comportamento humano ao reconsiderar a mente, até então menosprezada pelos behavioristas, em seus estudos. Os psicólogos e neurocientistas que adotam o princípio da seleção natural de Charles Darwin para compreender as raízes do comportamento e dos processos mentais, consideram que os genes e as experiências juntos estabelecem as conexões no cérebro humano, dotando a espécie de uma maior capacidade de aprendizagem e adaptação. Eles asseveram que existem mais semelhanças de comportamento em nossa espécie do que se possa imaginar. Os mecanismos neurais desencadeados por uma emoção, como o medo, são os mesmos em todos os humanos, de onde argumenta-se que as reações tendem a ser parecidas, dado o instinto de preservação da espécie. Os estudos em psicologia e neurociência sobre o comportamento humano foram aplicados a um conjunto de filmes do Instituto de Pesquisas e Estudos Sociais (IPES), produzidos no período de 1962 a 1964 dentro de uma campanha ideológica que, segundo o cientista social e historiador René Armand Dreifuss, culminou na desestabilização e derrocada do então presidente João Goulart. / The present work proposes to consider in the set of interpretative models of History the studies carried out in neuroscience and psychology on the biological and psychosocial bases of human behavior. Cognitive psychology has revolutionized the understanding of human behavior by reconsidering the mind, until then disregarded by behaviorists, in their studies. Psychologists and neuroscientists who adopt Charles Darwin\'s principle of natural selection to understand the roots of behavior and mental processes, consider that genes and experiences together establish connections in the human brain, giving the species a greater capacity for learning and adaptation. They assert that there are more similarities in behavior in our species than one can imagine. The neural mechanisms triggered by an emotion, such as fear, are the same in all humans, from which it is argued that reactions tend to be similar, given the instinct for the preservation of the species. The studies in psychology and neuroscience on human behavior were applied to a set of films of the Brazilian Institute of Research and Social Studies (IPES), produced between 1962 and 1964 within an ideological campaign that, according to the social scientist and historian René Armand Dreifuss, culminated in the destabilization and overthrow of then-President João Goulart.
2

\"O Brasil precisa de você\": uma leitura da propaganda produzida pelo IPES a partir das bases biológicas do comportamento humano (1962 - 1964) / \"O Brasil precisa de você\": a reading of the propaganda produced by the Brazilian IPES from the biological bases of human behavior (1962- 1964)

Celia Regina Justo Kaufmann 21 August 2017 (has links)
O presente trabalho propõe considerar no conjunto de modelos interpretativos da História os estudos realizados em neurociência e psicologia sobre as bases biológicas e psicossociais do comportamento humano. A psicologia cognitiva revolucionou o entendimento do comportamento humano ao reconsiderar a mente, até então menosprezada pelos behavioristas, em seus estudos. Os psicólogos e neurocientistas que adotam o princípio da seleção natural de Charles Darwin para compreender as raízes do comportamento e dos processos mentais, consideram que os genes e as experiências juntos estabelecem as conexões no cérebro humano, dotando a espécie de uma maior capacidade de aprendizagem e adaptação. Eles asseveram que existem mais semelhanças de comportamento em nossa espécie do que se possa imaginar. Os mecanismos neurais desencadeados por uma emoção, como o medo, são os mesmos em todos os humanos, de onde argumenta-se que as reações tendem a ser parecidas, dado o instinto de preservação da espécie. Os estudos em psicologia e neurociência sobre o comportamento humano foram aplicados a um conjunto de filmes do Instituto de Pesquisas e Estudos Sociais (IPES), produzidos no período de 1962 a 1964 dentro de uma campanha ideológica que, segundo o cientista social e historiador René Armand Dreifuss, culminou na desestabilização e derrocada do então presidente João Goulart. / The present work proposes to consider in the set of interpretative models of History the studies carried out in neuroscience and psychology on the biological and psychosocial bases of human behavior. Cognitive psychology has revolutionized the understanding of human behavior by reconsidering the mind, until then disregarded by behaviorists, in their studies. Psychologists and neuroscientists who adopt Charles Darwin\'s principle of natural selection to understand the roots of behavior and mental processes, consider that genes and experiences together establish connections in the human brain, giving the species a greater capacity for learning and adaptation. They assert that there are more similarities in behavior in our species than one can imagine. The neural mechanisms triggered by an emotion, such as fear, are the same in all humans, from which it is argued that reactions tend to be similar, given the instinct for the preservation of the species. The studies in psychology and neuroscience on human behavior were applied to a set of films of the Brazilian Institute of Research and Social Studies (IPES), produced between 1962 and 1964 within an ideological campaign that, according to the social scientist and historian René Armand Dreifuss, culminated in the destabilization and overthrow of then-President João Goulart.
3

[en] MAKING (IN)CONVENIENT TRUTHS: JEAN MANZON AND HIS MODELS OF SYMBOLIC CONSTRUCTION / [pt] FABRICANDO VERDADES (IN)CONVENIENTES: JEAN MANZON E SEUS MODELOS DE CONSTRUÇÃO SIMBÓLICA

JULIANA VICTORIA MILARE CORREA DE ANDRADE 28 June 2019 (has links)
[pt] Essa dissertação tem o objetivo de analisar a trajetória profissional de Jean Manzon, de modo a tentar compreender as particularidades de seu discurso e de sua estética produtiva. Considerado um dos maiores cineastas em atividade no Brasil, nos anos de 1950 e 1960, o francês Manzon possuía um acervo estimável de curtas-metragens; muitos deles produzidos sob encomenda. Devido ao prestígio alcançado junto a políticos, empresários e figuras públicas, seu material audiovisual era visto como instrumento de divulgação de promessas, realizações e premissas ideológicas. Além de problematizar a respeito do estilo narrativo e imagético de seu trabalho, esta pesquisa também abarca questões relacionadas à conduta de Manzon enquanto publicitário das ideias defendidas em seus filmes. Sua suposta militância em relação ao IPÊS e suas preferências pessoais, manifestadas a partir dos acordos firmados com seus parceiros, norteiam um dos debates centrais deste estudo. / [en] This dissertation aims to analyze the professional trajectory of Jean Manzon, in order to understand the particularities of his speech and his productive aesthetics. Considered one of the greatest active filmmakers in Brazil, in the 1950s and 1960s, the French Manzon possesses an estimable collection of short films; the images are custom made. Due to the prestige achieved with politicians, businessmen, and public figures, his audiovisual material was seen as an instrument for dissemination of promises, achievements and ideological premises. In addition to problematizing about the narrative and imagery style of his work, this research also covers issues related to Manzon s conduct as an advertiser of the ideas defended in his films. His supposed militancy in relation to IPÊS and his personal preferences, expressed through the agreements reached with his partners, guide one of the central debates of this paper.
4

Estrutura organizacional : proposta de intervenção na estrutura da Secretaria de Programas de Pós-Graduação da Universidade de Brasília Campus Planaltina

Dourado Júnior, Aristides Alvares 29 February 2016 (has links)
Dissertação (mestrado)—UnB/Planaltina, Programa de Pós-Graduação em Gestão Pública, Mestrado Profissional em Gestão Pública, 2016. / Submitted by Albânia Cézar de Melo (albania@bce.unb.br) on 2016-04-12T14:45:19Z No. of bitstreams: 1 2016_AristidesAlvaresDouradoJunior.pdf: 1990522 bytes, checksum: 556968558967f0a2889fe401ef297c52 (MD5) / Approved for entry into archive by Raquel Viana(raquelviana@bce.unb.br) on 2016-04-27T17:42:27Z (GMT) No. of bitstreams: 1 2016_AristidesAlvaresDouradoJunior.pdf: 1990522 bytes, checksum: 556968558967f0a2889fe401ef297c52 (MD5) / Made available in DSpace on 2016-04-27T17:42:27Z (GMT). No. of bitstreams: 1 2016_AristidesAlvaresDouradoJunior.pdf: 1990522 bytes, checksum: 556968558967f0a2889fe401ef297c52 (MD5) / Este estudo realiza uma proposta de intervenção na Estrutura Organizacional da Secretaria dos Programas de Pós-Graduação (stricto sunsu) da Universidade de Brasília, campus Planaltina (FUP), como consequência da necessidade em se adotar um design ajustado à realidade complexa do ambiente de inserção da Universidade da atualidade, focando melhorias na gestão administrativa e no desempenho da Unidade organizacional e, sucessivamente, no conceito da Pós-Graduação juntamente à Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES). Com base na literatura pertinente ao tema, foram apresentadas e discutidas diversas concepções teóricas acerca de estrutura organizacional, focalizando evolução histórica das organizações públicas e privadas, os elementos componentes e seus condicionantes. Sob a forma de diagnóstico, os resultados obtidos por meio de análise documental e entrevistas semi-estruturadas possibilitaram a categorização desse modelo na Unidade organizacional pesquisada. Foram identificadas cinco categorias relacionadas a função, composição, canais de comunicação, disfunções e pontos de melhoria. Conclui-se que a estrutura administrativa a ser proposta deve ser matricial, com atribuições claramente definidas no Regimento Interno da Unidade Acadêmica, com relacionamento funcional com a Diretoria de Pós-Graduação do Decanato de Pós-Graduação (DIRPG/DPP) e com a Coordenação Geral de Pós-Graduação da FUP (CCPG) e com os Coordenadores de Programas, porque permite à Unidade capacidade de melhor se adequar às mudanças sociais, políticas e tecnológicas, possibilitando flexibilidade, eficiência, atendimento contínuo e qualidade, proporcionando maior satisfação aos servidores e cidadãos. _______________________________________________________________________________________________ ABSTRACT / This study proposes an intervention in the organizational structure of the Department of Post-Graduation Programs (strictu sensu) at the University of Brasilia, Planaltina campus (FUP), as a result of the necessity to adopt an design adjusted to the complex reality of the integrated environment at the University nowadays, focusing on improvements in the administration and performance of the organizational units and hence the conception of the Post-Graduation activities considering CAPES Institution rules. Based on the literature concerning the matter, it has been presented and discussed several theoretical conceptions of organizational structure, focusing on the historical evolution of public and private organizations, as well as some pertinent elements and their main aspects. Through a diagnostic analysis, the obtained results have allowed the model categorization in the researched Organizational Unit, considering documental analysis and semi-structured interviews. Five categories were identified, related to the following aspects: functions, composition, communication channels, dysfunctions and points for improvement. It is concluded that the proposed administrative structure should be deployed as a matrix, with clearly defined responsibilities of the Academic Internal Regulations Department, which presents several bonds with the Post-Graduation Deanery Department (DIRPG / DPP) and the FUP Post-Graduation Department (CCPG), as well as the Post-Graduation Program coordinators, considering that this structure would allow the capacity to adapt the organizational unit to social, political and technological changes, enabling flexibility, efficiency, continuous service and quality, providing satisfaction to employees and citizens.
5

Du fullerène au graphène : études spectroscopiques de l'interaction de systèmes pi-conjugués avec des surfaces solides

Bocquet, Francois 20 March 2012 (has links)
Nous étudions l'adsorption de molécules de C60 sur deux reconstructions riches en silicium du 6H-SiC(0001) par IPES, UPS et XPS. Nous mettons en évidence que l'adsorption de C60 sur (3*3) est singulière et définit un nouveau type de liaison entre C60 et substrat : liaison covalente forte avec désorption par recuit à haute température et récupération de la reconstruction de surface. Ces expériences illustrent la complexité de la liaison Si-C60 et permettent une nouvelle mise en perspective.En combinant ARPES à basse énergie de photon et DFT sur une monocouche de ZnPc sur Ag(110), nous prouvons que l'effet de "Umklapp de surface" est effectif pour un réseau de molécules organiques organisé à grande distance. C'est à dire que les conditions de sortie des photoélectrons de volume sont modifiées par la présence du réseau.Nous démontrons aussi que l'HREELS est une technique de choix pour l'étude de l'adsorption d'hydrogène sur graphène, et l'étude de l'interaction d'un plan de graphène sur un substrat, ici le SiC. En effet l'adsorption (réversible) d'atomes d'hydrogène sur du graphène permet à l'HREELS d'être sensible sous le plan de graphène. / We study by IPES, UPS and XPS the adsorption of fullerene on two silicon-rich reconstructions of 6H-SiC(0001). We show that adsorption of C60 on the (3*3) is singular and defines a new bonding type between C60 and a substrate: covalent bond accompanied by the desorption of molecules and the reconstruction's recovery. Our experiments shed a new light on the Si-C60 bounding complexity and provide new insights.By combining low photon energy ARPES and DFT on a monolayer of ZnPc on Ag(110), we provide a direct evidence that the "surface Umklapp'" effect is effective for long-range ordered organic films. Namely, the photoelectrons escape conditions are modified by the bare presence of the molecular lattice.We show that HREELS is a convenient tool to investigate the adsorption of hydrogen on graphene and the interaction of graphene with a substrate, SiC in our study. Indeed, the reversible adsorption of hydrogen on graphene permits the HREELS to gain sensitivity below the graphene layer.
6

Interplay of Strong Correlation, Spin-Orbit Coupling and Electron-Phonon Interactions in Quasi-2D Iridium Oxides

Paerschke, Ekaterina 30 May 2018 (has links) (PDF)
In the last decade, a large number of studies have been devoted to the peculiarities of correlated physics found in the quasi-two-dimensional square lattice iridium oxides. It was shown that this 5d family of transition metal oxides has strong structural and electronic similarities to the famous 3d family of copper oxides. Moreover, a delicate interplay of on-site spin-orbit coupling, Coulomb repulsion and crystalline electric field interactions is expected to drive various exotic quantum states. Many theoretical proposals were made in the last decade including the prediction of possible superconductivity in square-lattice iridates emerging as a sister system to high-Tc cuprates, which however met only limited experimental confirmation. One can, therefore, raise a general question: To what extent is the low-energy physics of the quasi-two-dimensional square-lattice iridium oxides different from other transition metal oxides including cuprates? In this thesis we investigate some of the effects which are usually neglected in studies on iridates, focusing on quasi-two-dimensional square-lattice iridates such as Sr2IrO4 or Ba2IrO4. In particular, we discuss the role of the electron-phonon coupling in the form of Jahn-Teller interaction, electron-hole asymmetry introduced by the strong correlations and some effects of coupling scheme chosen to calculate multiplet structure for materials with strong on-site spin-orbit coupling. Thus, firstly, we study the role of phonons, which is almost always neglected in Sr2IrO4, and discuss the manifestation of Jahn-Teller effect in the recent data obtained on Sr2IrO4 with the help of resonant inelastic x-ray scattering. When strong spin-orbit coupling removes orbital degeneracy, it would at the same time appear to render the Jahn-Teller mechanism ineffective. We show that, while the Jahn-Teller effect does indeed not affect the antiferromagnetically ordered ground state, it leads to distinctive signatures in the spin-orbit exciton. Second, we focus on charge excitations and determine the motion of a charge (hole or electron) added to the Mott insulating, antiferromagnetic ground-state of square-lattice iridates. We show that correlation effects, calculated within the self-consistent Born approximation, render the hole and electron case very different. An added electron forms a spin-polaron, which closely resembles the well-known cuprates, but the situation of a removed electron is far more complex. Many-body configurations form that can be either singlets and triplets, which strongly affects the hole motion. This not only has important ramifications for the interpretation of angle-resolved photoemission spectroscopy and inverse photoemission spectroscopy experiments of square lattice iridates, but also demonstrates that the correlation physics in electron- and hole-doped iridates is fundamentally different. We then discuss the application of this model to the calculation of scanning tunneling spectroscopy data. We show that using scanning tunneling spectroscopy one can directly probe the quasiparticle excitations in Sr2IrO4: ladder spectrum on the positive bias side and multiplet structure of the polaron on the negative bias side. We discuss in detail the ladder spectrum and show its relevance for Sr2IrO4 which is in general described by more complicated extended t-J -like model. Theoretical calculation reveals that on the negative bias side the internal degree of freedom of the charge excitation introduces strong dispersive hopping channels encaving ladder-like features. Finally, we discuss how the choice of the coupling scheme to calculate multiplet structure can affect the theoretical calculation of angle-resolved photoemission spectroscopy and scanning tunnelling spectroscopy spectral functions.
7

Interplay of Strong Correlation, Spin-Orbit Coupling and Electron-Phonon Interactions in Quasi-2D Iridium Oxides

Pärschke, Ekaterina 30 May 2018 (has links)
In the last decade, a large number of studies have been devoted to the peculiarities of correlated physics found in the quasi-two-dimensional square lattice iridium oxides. It was shown that this 5d family of transition metal oxides has strong structural and electronic similarities to the famous 3d family of copper oxides. Moreover, a delicate interplay of on-site spin-orbit coupling, Coulomb repulsion and crystalline electric field interactions is expected to drive various exotic quantum states. Many theoretical proposals were made in the last decade including the prediction of possible superconductivity in square-lattice iridates emerging as a sister system to high-Tc cuprates, which however met only limited experimental confirmation. One can, therefore, raise a general question: To what extent is the low-energy physics of the quasi-two-dimensional square-lattice iridium oxides different from other transition metal oxides including cuprates? In this thesis we investigate some of the effects which are usually neglected in studies on iridates, focusing on quasi-two-dimensional square-lattice iridates such as Sr2IrO4 or Ba2IrO4. In particular, we discuss the role of the electron-phonon coupling in the form of Jahn-Teller interaction, electron-hole asymmetry introduced by the strong correlations and some effects of coupling scheme chosen to calculate multiplet structure for materials with strong on-site spin-orbit coupling. Thus, firstly, we study the role of phonons, which is almost always neglected in Sr2IrO4, and discuss the manifestation of Jahn-Teller effect in the recent data obtained on Sr2IrO4 with the help of resonant inelastic x-ray scattering. When strong spin-orbit coupling removes orbital degeneracy, it would at the same time appear to render the Jahn-Teller mechanism ineffective. We show that, while the Jahn-Teller effect does indeed not affect the antiferromagnetically ordered ground state, it leads to distinctive signatures in the spin-orbit exciton. Second, we focus on charge excitations and determine the motion of a charge (hole or electron) added to the Mott insulating, antiferromagnetic ground-state of square-lattice iridates. We show that correlation effects, calculated within the self-consistent Born approximation, render the hole and electron case very different. An added electron forms a spin-polaron, which closely resembles the well-known cuprates, but the situation of a removed electron is far more complex. Many-body configurations form that can be either singlets and triplets, which strongly affects the hole motion. This not only has important ramifications for the interpretation of angle-resolved photoemission spectroscopy and inverse photoemission spectroscopy experiments of square lattice iridates, but also demonstrates that the correlation physics in electron- and hole-doped iridates is fundamentally different. We then discuss the application of this model to the calculation of scanning tunneling spectroscopy data. We show that using scanning tunneling spectroscopy one can directly probe the quasiparticle excitations in Sr2IrO4: ladder spectrum on the positive bias side and multiplet structure of the polaron on the negative bias side. We discuss in detail the ladder spectrum and show its relevance for Sr2IrO4 which is in general described by more complicated extended t-J -like model. Theoretical calculation reveals that on the negative bias side the internal degree of freedom of the charge excitation introduces strong dispersive hopping channels encaving ladder-like features. Finally, we discuss how the choice of the coupling scheme to calculate multiplet structure can affect the theoretical calculation of angle-resolved photoemission spectroscopy and scanning tunnelling spectroscopy spectral functions.
8

Electronic Properties and Chemistry of Metal / Organic Semiconductor/ S-GaAs(100) Heterostructures

Gavrila, Gianina Nicoleta 13 January 2006 (has links) (PDF)
Im Rahmen dieser Arbeit werden drei Perylen-Derivate als Zwischenschichten in Metall/organische Schicht/S-GaAs(100)-Heterostrukturen eingesetzt. Das Ziel dieser Arbeit ist, den Einfluss von unterschiedlichen chemischen Endgruppen auf die elektronischen und chemischen Eigenschaften der Grenzflächen, sowie auf die molekulare Orientierung in den organischen Schichten nachzuweisen. Die Moleküle 3,4,9,10-Perylentetracarbonsäure Dianhydrid (PTCDA), 3,4,9,10-PerylenTetraCarbonsäure DiImid (PTCDI) und Dimethyl-3,4,9,10-PerylenTetraCarbonsäure DiImid (DiMe-PTCDI) wurden durch organische Molekularstrahldeposition (OMBD) im Ultrahochvakuum auf Schwefel-passivierte GaAs(100):2x1-Substrate aufgedampft. Oberflächensensitive Charakterisierungsverfahren wie Photoemissionsspekroskopie (PES), Inverse Photoemissionsspektroskopie (IPES) und Nahkantenröntgenfeinstrukturmessungen (NEXAFS) wurden zur Charakterisierung eingesetzt. Theoretische Berechnungen mit Hilfe von Dichte-Funktional-Methoden wurden durchgeführt, um eine Zuordnung von verschiedenen Komponenten in Rumpfniveauspektren zu ermöglichen. Die NEXAFS-Messungen ermöglichen eine genaue Bestimmung der Molekülorientierung in Bezug zum Substrat. So lässt sich nachweisen, dass eine kleine Änderung von chemischen Endgruppen z.B. bei DiMe-PTCDI verglichen mit PTCDI, eine dramatische Änderung der Molekülorientierung hervorruft. Die Valenzbandspektren von DiMe-PTCDI zeigen eine energetische Dispersion von 0.2 eV, die auf eine -Orbital-Überlappung zurückzuführen ist und die Ausbildung von Valenzbändern belegt. Die Energieniveauanpassung an der organische Schicht/S-GaAs-Grenzfläche, sowie die Transport-Bandlücke von PTCDI, DiMe-PTCDI und PTCDA wurden mit Hilfe von PES und IPES bestimmt. Die elektronischen, chemischen und strukturellen Eigenschaften von Metall/Organische Schicht- Grenzflächen wurden mit Hilfe von Rumpfniveauspektroskopie und NEXAFS untersucht. Mg reagiert stark mit den Endgruppen von PTCDA und PTCDI, währenddessen die In-Atome an einem Ladungstransferprozess mit den Perylen-Kernen aller dreien Molekülen beteiligt sind, wobei der Betrag der transferierten Ladung maximal für den Fall von PTCDI wird. Während Mg sehr wenig in die organischen Schichten diffundiert, zeigt In sehr starke Eindiffusion in PTCDA-Schichten und schwache in PTCDI-Schichten.
9

Electronic Properties and Chemistry of Metal / Organic Semiconductor/ S-GaAs(100) Heterostructures

Gavrila, Gianina Nicoleta 21 October 2005 (has links)
Im Rahmen dieser Arbeit werden drei Perylen-Derivate als Zwischenschichten in Metall/organische Schicht/S-GaAs(100)-Heterostrukturen eingesetzt. Das Ziel dieser Arbeit ist, den Einfluss von unterschiedlichen chemischen Endgruppen auf die elektronischen und chemischen Eigenschaften der Grenzflächen, sowie auf die molekulare Orientierung in den organischen Schichten nachzuweisen. Die Moleküle 3,4,9,10-Perylentetracarbonsäure Dianhydrid (PTCDA), 3,4,9,10-PerylenTetraCarbonsäure DiImid (PTCDI) und Dimethyl-3,4,9,10-PerylenTetraCarbonsäure DiImid (DiMe-PTCDI) wurden durch organische Molekularstrahldeposition (OMBD) im Ultrahochvakuum auf Schwefel-passivierte GaAs(100):2x1-Substrate aufgedampft. Oberflächensensitive Charakterisierungsverfahren wie Photoemissionsspekroskopie (PES), Inverse Photoemissionsspektroskopie (IPES) und Nahkantenröntgenfeinstrukturmessungen (NEXAFS) wurden zur Charakterisierung eingesetzt. Theoretische Berechnungen mit Hilfe von Dichte-Funktional-Methoden wurden durchgeführt, um eine Zuordnung von verschiedenen Komponenten in Rumpfniveauspektren zu ermöglichen. Die NEXAFS-Messungen ermöglichen eine genaue Bestimmung der Molekülorientierung in Bezug zum Substrat. So lässt sich nachweisen, dass eine kleine Änderung von chemischen Endgruppen z.B. bei DiMe-PTCDI verglichen mit PTCDI, eine dramatische Änderung der Molekülorientierung hervorruft. Die Valenzbandspektren von DiMe-PTCDI zeigen eine energetische Dispersion von 0.2 eV, die auf eine -Orbital-Überlappung zurückzuführen ist und die Ausbildung von Valenzbändern belegt. Die Energieniveauanpassung an der organische Schicht/S-GaAs-Grenzfläche, sowie die Transport-Bandlücke von PTCDI, DiMe-PTCDI und PTCDA wurden mit Hilfe von PES und IPES bestimmt. Die elektronischen, chemischen und strukturellen Eigenschaften von Metall/Organische Schicht- Grenzflächen wurden mit Hilfe von Rumpfniveauspektroskopie und NEXAFS untersucht. Mg reagiert stark mit den Endgruppen von PTCDA und PTCDI, währenddessen die In-Atome an einem Ladungstransferprozess mit den Perylen-Kernen aller dreien Molekülen beteiligt sind, wobei der Betrag der transferierten Ladung maximal für den Fall von PTCDI wird. Während Mg sehr wenig in die organischen Schichten diffundiert, zeigt In sehr starke Eindiffusion in PTCDA-Schichten und schwache in PTCDI-Schichten.
10

Tailoring the Electronic and Optical Properties of Molecular Thin Films by Reducing and Oxidising Agents

Haidu, Francisc 13 January 2015 (has links) (PDF)
Heutzutage wächst die Nachfrage nach neuartigen Geräten, die teilweise (hybrid) oder völlig aus organischen halbleitenden Materialien hergestellt sind. Der Grund dafür sind die geringen Herstellungskosten sowie die hohe Flexibilität im Moleküldesign und damit einstellbare optische, elektronische und Spintronik-Eigenschaften. Bisher sind mit großem Erfolg organische Leuchtdioden (OLED), organische Solarzellen und gedruckte organische Elektronik-Bauelemente hergestellt worden. Auf Grund ihrer langen Spin-Lebensdauer sind Moleküle auch für Spintronik-Anwendungen sehr geeignet. In dieser Arbeit wurden die elektronischen und optischen Eigenschaften von vier ausgewählten Molekülen analysiert. Davon wurden Kupfer- und Mangan-Phthalocyanin (CuPc und MnPc) für die Untersuchung der Anordnung des Energieniveaus an der Metall-Organischen Halbleitern (M-O) Grenzfläche verwendet. Außerdem werden die andere zwei Moleküle tris(8-hydroxy-quinolinato) Aluminium(III) (Alq3) und N,N’-diphenyl-N,N’-bis(1-naphthyl)-1,1’-biphenyl-4,4’-diamine (α-NPD) häufig in OLED-Strukturen als Elektron- beziehungsweise Loch-Leiter verwendet. Die Proben sind mittels organischer Molekularstrahl-Abscheidung (OMBD) auf Co (oder Au) Folien beziehungsweise auf einseitig poliertem Si(111) Einkristall hergestellt worden. Im ersten Teil der Arbeit wurde die Entwicklung der Grenzfläche zwischen CuPc und Co (oder Au) Substrat mittels Valenzband- und Inverser Photoelektronen-spektroskopie (VB-PES und IPES) analysiert und herausgefunden, dass ein „Öffnung“ der Bandlücke mit dem Wachstum der Molekularschicht erfolgt. Ähnliches findet bei die MnPc/Co-Grenzfläche statt. Diese Erkenntnisse sind sehr wichtig für die Entwicklung von zukünftigen leistungsfähigen Spintronik Geräten. Der zweite Teil fokussiert auf die Änderungen der elektronischen Eigenschaften von MnPc und Alq3 während der Oxidation (O2-Aussetzung) beziehungsweise Reduktion (Kalium-Abscheidung). Abgesehen von den VB-PES und IPES Messungen, bieten die Röntgenphotoelektronenspektroskopie (XPS) und die Röntgen-Nahkante- Absorptions-Spektroskopie (NEXAFS) wichtige Informationen w. z. B. die Menge von K in der Molekülschicht und den Spin-Zustand im undotierten und im dotierten MnPc. Der dritte Teil beschäftigt sich mit den optischen Eigenschaften von MnPc, Alq3 und α-NPD als Reinmaterialien sowie mit K-dotierten Molekülen, in situ verfolgt mittels spektroskopischer Ellipsometrie (SE). Vom SE-Spektrum wurde der Imaginärteil der dielektrischen Funktion abgeleitet. Während α-NPD fast keine Änderung im Absorptionsspektrum nach der Dotierung zeigt, zeigt Alq3 dagegen ein Wandel zu einer dotierten Phase mit kleine Änderungen im Spektrum. Dabei hat MnPc drei stabile dotierte Phasen mit großen spektralen Änderungen. Außerdem zeigt die Oxidation von MnPc umgekehrt Eigenschaften zur dotierten Phase. Alle diese Messungen sind einzigartig und sehr wichtig für die Entwicklung von OLED und Spintronik Geräten.

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