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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.
871

Energia de interação cátion-ânion de líquidos iônicos dicatiônicos em fase gasosa / Interaction energy of cation-anion in dicationic ionic liquids in the gas phase

Hennemann, Bruno Luís 05 August 2016 (has links)
Electrospray ionization mass spectrometry (ESI-MS) with induced collision energy was used to carry out a comprehensive study on the interaction energies between cations and anions of dicationic ionic liquids. The influence of the anion ([Br]-, [NO3]-, [BF4]-, [SCN]- and [Cl]-) and the size of alkyl chain (n = 4,6,8 and 10) in the interaction energy of ionic liquids derived from the 1, n-bis (3-methylimidazolyl-1-yl) alkane with n = 4,6,8 and 10, in the gas phase was investigated. Three experiments were carried out to determine the cation-anion interaction energy: (i) ESI-MS of binary (1:1) mixtures of ionic liquids with different anions or cations; (Ii) ESI-MS of ionic liquid individually with variation of the applied collision energy and determination of the center of mass energy (Ecm) using the relation between the intensity of the precursor ion and the sum of the ions; (iii) the rate of variation of the intensity of the precursor ion as a function of collision energy at different concentrations of all ionic liquids was obtained. From this correlation, the cation-anion dissociation constant of the dicationic ionic liquids was obtained. The results showed the appearance of mixed species (example: [Bis-C8(MIM)22XY]- and [C8(MIM)XY]-) in the binary mixtures. The application of the induced collision energy in the mixtures allowed estimating which anion interacts more effectively with the cation. Also for this experiments, the dicationic ionic liquids with the anions [Cl]-, [Br]- and [NO3]- presented higher cation-anion interaction energy. The increasing order of interaction energy was [BF4]- <[SCN]- <[NO3]- <[Br]- <[Cl]-. The Ecm values for ionic liquids with different anions did not indicate trends in the interaction energy in relation to structural factors such as ionic radius and molecular volume. Thus, for the anions, it was found that the interaction increases in the following order: [SCN]- <[Cl]- <[NO3]- <[Br]- <[BF4]-. On the other hand, increasing the size of the spacer alkyl chain caused an increase in cation-anion interaction energy. As the concentration of the ionic liquid increased, an increase in the precursor ion intensity was observed. / A espectrometria de massa com ionização por electrospray (ESI-MS) com energia de colisão induzida foi utilizada para realizar um estudo compreensivo sobre as energias de interação entre cátions e ânions de líquidos iônicos dicatiônicos. Foi avaliada a influência do ânion ([Br]-, [NO3]-, [BF4]-, [SCN]- e [Cl]-) e o tamanho da cadeia alquílica espaçadora (n=4,6,8 e 10) na energia de interação dos líquidos iônicos dicatiônicos, derivados do 1,n-bis(3-metilimidazolil-1-íneo)alcano em fase gasosa. Três experimentos foram realizados para a determinação da energia de interação cátion-ânion: (i) ESI-MS de misturas binárias (1:1) de líquidos iônicos com diferentes ânions ou cátions; (ii) ESI-MS de cada líquido iônico individualmente com variação da energia de colisão aplicada e determinação da energia de centro de massa (Ecm) usando a relação entre intensidade do íon precursor e somatório dos íons. (iii) Por fim, foi obtida a taxa de variação da intensidade do íon precursor em função energia de colisão de todos os líquidos iônicos. A partir desta correlação, foi obtida a constante de dissociação cátion-ânion dos líquidos iônicos dicatiônicos. Os resultados mostraram o aparecimento de espécies mistas (exemplo: [Bis-C8(MIM)22XY]- e [C8(MIM)XY]-) nos experimentos das misturas. A aplicação da energia de colisão induzida nas misturas também permitiu estimar qual ânion interage mais efetivamente com o cátion. Ainda para este experimentos, os líquidos iônicos dicatiônicos com os ânions [Cl]-, [Br]- e [NO3]- apresentaram maior energia de interação cátion-ânion. A escala em ordem crescente de energia de interação foi [BF4]-< [SCN]- < [NO3]- < [Br]- < [Cl]-. Os valores de Ecm para os líquidos iônicos com diferentes ânions não indicou tendências na energia de interação em relação fatores estruturais tais como raio iônico e volume molecular. Dessa forma, para os ânions, foi encontrado que a interação aumenta na seguinte ordem: [SCN]-<[Cl]-<[NO3]-<[Br]-<[BF4]-. Por outro lado, o aumento do tamanho da cadeia alquílica espaçadora causou um aumento na energia de interação cátion-ânion. Com o aumento da concentração do líquido iônico, foi observado um aumento na intensidade do íon precursor.
872

Kommunikationens betydelse vid haverier till sjöss : En analys baserad på haverirapporter / The importance of communication in the case of accidents at sea : An analysis based on marine reports

Roos, Andreas, Stålmarck, Peter January 2018 (has links)
Antalet haverier som är orsakade av den mänskliga faktorn minskar inte. En del av den mänskliga faktorn ligger i kommunikation mellan olika parter inom sjöfarten, både sjö- och landbaserade. Denna studie är en litteraturstudie vars syfte är att undersöka hur den verbala kommunikationen har praktiserats och vilken betydelse den haft vid kollisioner och grundstötningar. Studien är baserad på haverirapporter från Statens Haveri-kommission som har analyserats med hjälp av ett verktyg specifikt framtaget för denna studie. Resultatet visar på en kommunikationsbrist i en betydande majoritet av de analyserade haverierna. Ofta brister det i kommunikationen mellan VTS och fartyg samt mellan lots och befälhavare. Vanligt förekommande är även språkförbistring där inte alla parter förstått det språket som använts vid kommunikationen.  Med hjälp av ett mer utbrett utövande av redan kända kommunikationstekniker skulle antalet olyckor och tillbud kunna minskas. / The number of marine accidents caused by the human error does not decrease. A part of the human error is in the communication between different agents within the maritime cluster, at sea and also in the landbased sector. This study is a literature study whose purpose is to investigate how the verbal communication has been practiced and what significance it has had in collisions and groundings. The study is based on reports from the Swedish Accident Investigation Authority with a tool specifically developed for this particular study. The result shows a communication gap in a decisive majority of the analyzed accidents. There is often a lack of communication between VTS and vessels as well as between pilots and commanders. Common prevalence is also language problem where not all parties understand the language used in the communication. With the help of a more widespread practice of already known communication technologies, the number of accidents could be reduced.
873

Problemas inversos em processos difusivos com retenção / Inverse problems in diffusive process with retention

Luciano Gonçalves da Silva 21 February 2013 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Um Estudo para a solução numérica do modelo de difusão com retenção, proposta por Bevilacqua et al. (2011), é apresentado, bem como uma formulação implícita para o problema inverso para a estimativa dos parâmetros envolvidos na formulação matemática do modelo. Através de um estudo minucioso da análise de sensibilidade e do cálculo do coeficiente de correlação de Pearson, são identificadas as chances de se obter sucesso na solução do problema inverso através do método determinístico de Levenberg-Marquardt e dos métodos estocásticos Algoritmo de Colisão de Partículas (Particle Collision Algorithm - PCA) e Evolução Diferencial (Differential Evolution - DE). São apresentados os resultados obtidos através destes três métodos de otimização para três casos de conjunto de parâmetros. Foi observada uma forte correlação entre dois destes três parâmetros, o que dificultou a estimativa simultânea dos mesmos. Porém, foi obtido sucesso nas estimativas individuais de cada parâmetro. Foram obtidos bons resultados para os fatores que multiplicam os termos diferenciais da equação que modela o fenômeno de difusão com retenção. / A Study for the numerical solution of the diffusion model with retention, proposed by Bevilacqua et al.(2011), using the finite difference method is presented, as well as an implicit formulation for the inverse problem to estimate the parameters involved in the formulation of the mathematical model. Through of a thorougth study of sensitivity analysis and calculating the Pearson correlation coefficient, are identified the chances of success in solving the inverse problem using the deterministic method of Levenberg-Marquardt and stochastic methods Particle Collision Algorithm - PCA and Differential Evolution - DE. Presents the results obtained from these three methods of optimization for three cases of parameter set. We observed a strong correlation between two of these three parameters, making it difficult to estimate simultaneously the same. However, success was obtained in the individual estimates for each parameter. Good results were obtained for the factors that increase the terms of the differential equation that models the phenomenon of diffusion with retention.
874

Colisão de direitos fundamentais, argumentação e ponderação

Gavião Filho, Anizio Pires January 2010 (has links)
O objetivo central desta investigação é demonstrar que a ponderação é racional. A proposição normativa particular concreta resultante de um caso de colisão de direitos fundamentais resolvido pela ponderação pode ser justificada racionalmente. O que se pretende sustentar é que o problema não está na ponderação, mas como ela é realizada para solucionar os casos de colisão de direitos fundamentais. A ponderação somente pode pretender racionalidade quando sustentada por razões dadas conforme regras. A proposição decisiva desta investigação é a de que a ponderação, como atividade argumentativa, deve observar as regras da argumentação racional. Essas regras são as regras da argumentação prática geral e da argumentação jurídica, formuladas pela teoria do discurso prático geral e do discurso jurídico. Elas configuram a base das regras próprias da ponderação racional. / The goal of this research is to show that balancing is rational. The particular concrete normative statement resulting from a collision of constitutional rights resolved by balancing can be justified rationally. The aim is to sustain that the problem is not balancing itself, but how it is used to solve the cases of collision of constitutional rights.The balancing can be rational only if supported by reasons given under rules. A crucial proposition of this research is that the balancing, as argumentative activity, must observe the rules of rational legal reasoning. These rules are the rules of the general practice argumentation and the rules of the legal reasoning, raised by the theory of general practical discourse and legal discourse. They make the basis of its own rules of rational balancing.
875

O direito fundamental à não-autoincriminação e a influência do silêncio do acusado no convencimento do juiz penal

Trois Neto, Paulo Mário Canabarro January 2009 (has links)
O direito fundamental à não-autoincriminação encontra seu fundamento jurídicoconstitucional na conexão dos princípios constitucionais da dignidade humana, do procedimento correto, da ampla defesa e da presunção de inocência. Todas as condutas passivas cuja adoção diga respeito a uma opção tomada pelo acusado na condição de sujeito processual – dentre as quais o exercício passivo da autodefesa no interrogatório judicial – estão prima facie protegidas pelo direito de não se autoincriminar. O problema da influência do silêncio do acusado no interrogatório judicial apresenta uma colisão do direito à nãoautoincriminação com o bem coletivo da eficiência da justiça penal e exige, consequentemente, soluções de acordo com os critérios da teoria dos princípios e da argumentação jusfundamental. A busca da concordância prática dos princípios colidentes exige a consideração de que, embora o comportamento processual do acusado não esteja sujeito a valorações, a omissão do acusado em responder ao interrogatório pode privar a defesa de uma oportunidade para contribuir à refutação ou ao enfraquecimento do grau de confirmação da hipótese acusatória. / The fundamental right against self-incrimination has its legal-constitutional basis in the connection of the constitutional principles of human dignity, fair trial, ample defense against criminal charges and presumption of innocence. All the passive conducts of which adoption refers to a choice of the accused in the condition of subject of the process – such as the passive exercise of self-defense at the examination – are prima facie protected by the right against self incrimination. The issue of the charged’s silence influence in the judicial examination presents a collision of the right against self incrimination with the collective good of the criminal justice efficiency and demands, therefore, solutions according to the criteria of principles theory and fundamental-legal arguing. The search for practical compliance of the colliding principles requires considering that although the processual behavior of the charged is not submitted to judgments of value, the omission of the accused in answering the examination may deprive defense the opportunity to contribute in denying or minimizing the confirmation degree of the accusatory hypothesis.
876

Colisão de direitos fundamentais, argumentação e ponderação

Gavião Filho, Anizio Pires January 2010 (has links)
O objetivo central desta investigação é demonstrar que a ponderação é racional. A proposição normativa particular concreta resultante de um caso de colisão de direitos fundamentais resolvido pela ponderação pode ser justificada racionalmente. O que se pretende sustentar é que o problema não está na ponderação, mas como ela é realizada para solucionar os casos de colisão de direitos fundamentais. A ponderação somente pode pretender racionalidade quando sustentada por razões dadas conforme regras. A proposição decisiva desta investigação é a de que a ponderação, como atividade argumentativa, deve observar as regras da argumentação racional. Essas regras são as regras da argumentação prática geral e da argumentação jurídica, formuladas pela teoria do discurso prático geral e do discurso jurídico. Elas configuram a base das regras próprias da ponderação racional. / The goal of this research is to show that balancing is rational. The particular concrete normative statement resulting from a collision of constitutional rights resolved by balancing can be justified rationally. The aim is to sustain that the problem is not balancing itself, but how it is used to solve the cases of collision of constitutional rights.The balancing can be rational only if supported by reasons given under rules. A crucial proposition of this research is that the balancing, as argumentative activity, must observe the rules of rational legal reasoning. These rules are the rules of the general practice argumentation and the rules of the legal reasoning, raised by the theory of general practical discourse and legal discourse. They make the basis of its own rules of rational balancing.
877

Mecanismo de controle de potência para estimativa de etiquetas em redes de identificação por rádio frequência

Lucena Filho, Walfredo da Costa 03 August 2015 (has links)
Submitted by Geyciane Santos (geyciane_thamires@hotmail.com) on 2015-11-23T21:24:44Z No. of bitstreams: 1 Dissertação - Walfredo da Costa Lucena Filho.pdf: 2083187 bytes, checksum: 72f63311dba60bbea7ef2d5cc474c601 (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2015-11-30T19:51:08Z (GMT) No. of bitstreams: 1 Dissertação - Walfredo da Costa Lucena Filho.pdf: 2083187 bytes, checksum: 72f63311dba60bbea7ef2d5cc474c601 (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2015-11-30T19:55:39Z (GMT) No. of bitstreams: 1 Dissertação - Walfredo da Costa Lucena Filho.pdf: 2083187 bytes, checksum: 72f63311dba60bbea7ef2d5cc474c601 (MD5) / Made available in DSpace on 2015-11-30T19:55:40Z (GMT). No. of bitstreams: 1 Dissertação - Walfredo da Costa Lucena Filho.pdf: 2083187 bytes, checksum: 72f63311dba60bbea7ef2d5cc474c601 (MD5) Previous issue date: 2015-08-03 / FAPEAM - Fundação de Amparo à Pesquisa do Estado do Amazonas / An RFID system is typically composed of a reader and a set of tags. An anti-collision algorithm is necessary to avoid collision between tags that respond simultaneously to a reader. The most widely used anti-collision algorithm is DFSA (Dynamic Framed Slotted ALOHA) due to its simplicity and low computational cost. In DFSA algorithms, the optimal TDMA (Time Division Multiple Access) frame size must be equal to the number of unread tags. If the exact number of tags is unknown, the DFSA algorithm needs a tag estimator to get closer to the optimal performance. Currently, applications have required the identification of large numbers of tags, which causes an increase in collisions and hence the degradation in performance of the traditional algorithms DFSA. This work proposes a power control mechanism to estimate the number of tags for radio frequency identification networks (RFID). The mechanism divides the interrogation zone into subgroups of tags and then RSSI (Received Signal Strength Indicator) measurements estimate the number of tags in a subarea. The mechanism is simulated and evaluated using a simulator developed in C/C++ language. In this study, we compare the number of slots and identification time, with ideal DFSA algorithm and Q algorithm EPCglobal standard. Simulation results shows the proposed mechanism provides 99% performance of ideal DFSA in dense networks, where there are many tags. Regarding the Q algorithm, we can see the improvement in performance of 6.5%. It is also important to highlight the lower energy consumption of the reader comparing to ideal DFSA is 63%. / Um sistema de identificação por rádio frequência (RFID) é composto basicamente de um leitor e etiquetas. Para que o processo de identificação das etiquetas seja bem sucedido, é necessário um algoritmo anticolisão a fim de evitar colisões entre etiquetas que respondem simultaneamente à interrogação do leitor. O algoritmo anticolisão mais usado é o DFSA (Dynamic Framed Slotted ALOHA) devido à sua simplicidade e baixo custo computacional. Em algoritmos probabilísticos, tal como o DFSA, o tamanho ótimo do quadro TDMA (Time Division Multiple Access) utilizado para leitura das etiquetas deve ser igual à quantidade de etiquetas não lidas. Uma vez que no processo de leitura, normalmente não se sabe a quantidade exata de etiquetas, o algoritmo DFSA faz uso de um estimador para obter um desempenho mais próximo do ideal. Atualmente, as aplicações têm demandado a identificação de grandes quantidades de etiquetas, o que ocasiona um aumento das colisões e, consequentemente, a degradação no desempenho dos algoritmos DFSA tradicionais. Este trabalho propõe um mecanismo de controle de potência para estimar a quantidade de etiquetas em redes de identificação por rádio frequência (RFID). O mecanismo baseia-se na divisão da área de interrogação em subáreas e, consequentemente, subgrupos de etiquetas. Tal divisão é utilizada para realizar medições de RSSI (Received Signal Strength Indicator) e, assim, estimar a quantidade de etiquetas por subárea. O mecanismo é simulado e avaliado utilizando um simulador próprio desenvolvido em linguagem C/C++. Neste estudo, comparam-se os resultados de quantidade de slots e tempo de identificação das etiquetas, com os obtidos a partir da utilização dos algoritmos DFSA ideal e algoritmo padrão Q da norma EPCglobal. A partir dos resultados da simulação, é possível perceber que o mecanismo proposto apresenta desempenho 99% do DFSA ideal em redes densas, onde há grande quantidade de etiquetas. Em relação ao algoritmo Q, percebe-se a melhoria de 6,5% no desempenho. É importante ressaltar também a redução no consumo de energia do leitor em torno de 63% em relação ao DFSA ideal.
878

Recherche de leptoquarks de troisième génération dans l’expérience CMS au LHC / Search for third generation Leptoquarks in the CMS experiment at LHC

Chasserat, Julien 05 March 2014 (has links)
L'expérience CMS (Compact Muon Solenoid), construite sur l'anneau du LHC (Large Hadron Collider) a enregistré une quantité colossale de données provenant des collisions proton-proton de 2009 à 2012 à des énergies dans le centre de masse de 7 TeVet 8 TeV. Cette expérience est consacrée aux mesures de précision des paramètres du modèle standard, à l'étude du boson de Higgs ainsi qu'à la mise à l'épreuve de théories au-delà du modèle standard. Un certain nombre de ces théories prévoient l'existence de particules appelées leptoquarks, de nouveaux bosons se couplant à la fois aux leptons et au quarks. La première partie de cette thèse est consacrée à la présentation du Modèle Standard des particules et à une introduction théorique aux leptoquarks. La seconde présente brièvement le fonctionnement du LHC et de l'expérience CMS. La troisième partie est dédiée au travail effectué dans le groupe générateur de CMS au cours de la première année de ma thèse. Cette mission consistait principalement à générer et à valider massivement des évènements Monte-Carlo avec le logiciel Madgraph pour l'ensemble de la collaboration CMS. Enfin, la dernière partie porte sur l'analyse de données et la recherche de paires de leptoquarks scalaires de troisième génération. Trois canaux de désintégration des LQ sont envisagés : en quark top et lepton tau, en quark top et neutrino et enfin en quark top et muon. Cette étude est basée sur l'ensemble des données enregistrées par l 'expérience CMS au cours de l'année 2012. Ce qui représente une luminosité intégrée totale de 19,7 fb. Différentes sélections basées sur au moins un lepton et de nombreux jets sont examinées afin de définir les régions présentant les meilleures efficacités de signal par rapport au fond du Modèle Standard. Enfin, une optimisation des coupures sur des variables très discriminantes est réalisée afin d'obtenir les meilleures limites à 95% de confiance sur les sections efficaces de production des leptoquarks. Aucun excès significatif par rapport aux prévisions du modèle standard n'a pu être mis en évidence ce qui a permis de poser des limites sur les sections efficaces de production des leptoquarks. Les leptoquarks de troisième génération sont exclus jusqu'à des masses de 320 GeV à 95 % de niveau de confiance pour le canal top tau, jusqu'à 240 GeV pour le canal top nu et jusqu'à 910 GeV pour le canal top mu / Installed on the LHC (Large Hadron Collider) ring, the CMS experiment (Compact Muon Solenoid) recorded a great amount of proton-proton collisions data from 2009 to 2012 at center of mass energies of 7 TeV and 8 TeV. This experiment was designed for precise measurements of the Standard Model parameters, for Higgs boson studies and to test theories beyond the standard model. Some of these theories foresee the existence of leptoquarks which are new bosons with couplings to both leptons and quarks. The first part of this thesis is dedicated to a presentation of the Standard Model and to a leptoquarks theoretical introducion. The second one briefly explains how the LHC and the CMS experiment work. The third part details the work accomplished during the first year of my thesis in the CMS generator group. Finaly, the last one deals with data analysis and the search of third generation leptoquarks pair production. Three LQ desintegration channels are investigated : to a top quark and a tau lepton, to a top quark and a neutrino and at last to a top quark and a muon. This study is based on the full integrated luminosity recorded during 2012, namely 19.7 fb. Various selections requiring at least one lepton and several jets are scrutinized in order to identify the regions with best signal efficiency regarding to Standard model backgrounds. Finally, a selection optimisation on discriminative variables is performed to extract the best 95 No significative excess with respect to Standard Model expectations was found. Thus we were able to set limits on the leptoquarks pair production cross sections. Third generation leptoquarks with masses below 320 GeV, 240 GeV and 910 GeV are excluded for the top tau, top nu and top mu channels, respectively
879

Úloha helikázy RECQ5 při stabilizaci a opravě replikačních vidlic po jejich kolizi s transkripčním komplexem / Role of human RECQ5 helicase in the resolution of conflicts between transcription and replication complexes

Fryzelková, Jana January 2017 (has links)
The progression of replication forks can be slowed down or paused by various external and internal factors during DNA replication. This phenomenon is referred to as replication stress and substantially contributes to genomic instability that is a hallmark of cancer. Transcription complex belongs to the internal replication-interfering factors and represents a barrier for progression of the replication complex. The replication forks are slowed down or paused while passing through the transcriptionally active regions of the genome that can lead to subsequent collapse of stalled forks and formation of DNA double-strand breaks, especially under conditions of increased replication stress. DNA helicase RECQ5 is significantly involved in maintenance of genomic stability during replication stress, but the mechanisms of its action are not clear. In this diploma theses, we have shown that RECQ5 helicase, in collaboration with BRCA1 protein, participates in the resolution of collisions between replication and transcription complexes. BRCA1 protein is a key factor in the homologous recombination process, which is essential for the restart of stalled replication forks. Furthermore, we have shown that RECQ5 helicase is involved in ubiquitination of PCNA protein at stalled replication forks. Key words DNA...
880

The collision dynamics of OH(A)+H2

Seamons, Scott Andrew January 2015 (has links)
This thesis presents a joint experimental and theoretical study of a bimolecular collision between OH(A) and H<sub>2</sub> diatoms. The study focuses on the relationship between the initial, <b><i>j</i></b>, and final rotational angular momentum, <b><i>j'</i></b>. This relationship is explored from both a scalar point of view by measuring rotational energy transfer (RET), and a vectorial viewpoint by considering the collisional depolarisation. The experimental technique used in this investigation, Zeeman quantum beat spectroscopy, is first demonstrated by applying it to the determination of the lab-frame orientation of OH(X) photofragments following the photolysis of H<sub>2</sub>O<sub>2</sub>. The H<sub>2</sub>O<sub>2</sub> is photolysed by circularly-polarised light at 248 nm, and Zeeman quantum beat spectroscopy probes the angular momentum orientation as a function of the photofragment spin-rotation level. The results of this experiment are compared with orientation parameters predicted by a simulation that couples the rotation of the parent molecule to the torsional motion during bond cleavage. The calculations from the model agree qualitatively with those from the experiment. The Zeeman quantum beat spectroscopy technique is then used to monitor the evolution of angular momentum polarisation of OH(A) radicals during collisions with H<sub>2</sub>. The technique allows for the determination of depolarisation cross sections for oriented and aligned distributions, as a result of collisions with H<sub>2</sub>. Alongside this, cross sections for collisional quenching to non-reactive OH(X)+H<sub>2</sub> and reactive H<sub>2</sub>O+H products are determined. By resolving the fuorescence with a monochromator the contributions to depolarisation from elastic collisions (the elastic depolarisation cross sections) are measured alongside cross sections for RET. Cross sections for total depolarisation and rotational energy transfer demonstrate only weak dependence on the rotational quantum number of the OH(A) radical, <i>N</i><sub>OH</sub>. Competing quenching processes that fall with <i>N</i><sub>OH</sub> are likely a considerable cause of this weak dependence. Furthermore, the polarisation of the angular momentum of OH(A) is randomised following RET. The elastic depolarisation cross sections make only a small contribution to the depolarisation and fall with increasing <i>N</i><sub>OH</sub>. Collectively these trends have not been seen previously in similar studies on OH(A) collisions with atomic colliders. For the theoretical calculations, a four-atom quasi-classical trajectory (QCT) method has been developed, utilising Lagrangian multipliers to fix the OH(A) and H<sub>2</sub> bonds. The calculations demonstrate that collisions involving the formation of complexes that survive for several rotational periods are prevalent in this collision system, and that these lead to large amounts of depolarisation. The calculations also demonstrate that RET in the H<sub>2</sub> diatom supports higher levels of RET in OH(A) than seen in previous triatomic systems. Additionally, when one diatom is depolarised the accompanying diatom is typically also depolarised. These trends, at least in part, are owed to the highly attractive and anisotropic potential energy surface (PES) describing the interaction. The QCT calculations overestimate the experimentally-measured cross sections by more than a factor of 2. The calculations are adiabatic and do not account for the non-adiabatic activity associated with this collision system, and this is likely one cause of the discrepancies. In an attempt to further account for this overestimation, alternative angular momentum binning approaches for the QCT calculations are developed, but with limited success. Further exploration of the topology of the PES used in the calculations suggests that inadequacies in this surface are a major contributor to the discrepancies.

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