Thesis (Ph. D.)--University of Missouri-Columbia, 1996. / Typescript. Vita. Includes bibliographical references (leaves 116-121). Also available on the Internet.

Thesis (Ph.D.) -- McMaster University, 2001. / Includes bibliographical references (leaves 136-143). Also available via World Wide Web.

Made available in DSpace on 2014-06-11T19:32:21Z (GMT). No. of bitstreams: 0 Previous issue date: 2005-11-18Bitstream added on 2014-06-13T20:43:18Z : No. of bitstreams: 1 filemon_ke_dr_rcla.pdf: 3595270 bytes, checksum: fe777c131792428b6cb28f195196ddad (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / O Sistema de Processo de Certificação de Kimberley foi instituído pela Organização das Nações Unidas (ONU) no ano 2000. O Brasil que ocupa a nona posição no ranking dos paises produtores de diamantes, aderiu a esse acordo internacional que tem servido como um mecanismo de certificação de origem geográfica de diamantes brutos destinados à exportação e importação. Considerando-se a extrema importância na determinação da procedência dos diamantes brutos. Foi desenvolvida a presente pesquisa visando caracterizar lotes representativos de diamantes da província kimberlítica de Juína (MT), e dos distritos de Cacoal (RO), Espigão Dþoeste (RO) e Diamantina (MG), utilizando técnicas de fluorescência, espectroscopia infravermelha, fotoluminescência (PL), ressonância paramagnética eletrônica (EPR) e Raman, além de estudos de morfologia, texturas de superfícies e granulometria. Os dados obtidos, através da análise estatística de populações das quatro áreas diamantíferas estudadas mostraram predomínio de diamantes de cor marrom em Juína, e de pedras incolores nos distritos do Cacoal, Espigão Dþoeste e Diamantina. A província de Juína destaca-se pela presença de fragmentos irregulares e raríssimos cristais dodecaedros e octaedros, enquanto nos distritos de Diamantina e de Espigão Dþoeste predominam diamantes com hábito dodecaedro. O comportamento ao infravermelho mostrou, na província kimberlítica de Juína uma proporção elevada de diamantes tipo IIa (15%), diamantes tipo IaB (20%) e diamantes tipo IaAB (65%) apresentando este último, alto estado de agregação do nitrogênio. Os diamantes dos distritos de Cacoal, Espigão Dþoeste e Diamantina enquadram-se na classificação do tipo IaAB, variando seu estado de agregação de nitrogênio. Observados sob luz ultravioleta, os diamantes estudados mostraram diferenças nas cores de fluorescência,... / In 2000 the United Nations established the Kimberley Process Certification System in order to avoid illegal diamond trading, especially those from the African continent Brazil, which holds the ninth position in the diamonds trading ranking has joined such international agreement that helps as a geographic origin certification mechanism for exporting and importing. Considering the importance in determining the unpolished diamonds origin, the present study have been developed with the aim objective to describe representative diamond amounts or lots from the Kimberlitic Province of Juína (MT), Cacoal (RO) and Espigao Df oeste (RO) and Diamantina (MG) districts. Using spectroscopy techniques, infrared, photoluminescence, electronic paramagnetic resonance and Raman have been used. In addition, other techniques and procedures such as morphology 1 surface roughness and granulometry were applied. Statistical population analysis of four studied diamond bearing areas indicated several particular characteristics. Where some colors highly predominate in a determined region. Brownish colored diamonds are predominant in Juína provence and colorless crystals are present in Cacoal, Espigão Dþoeste and Diamantina districts. The irregular habit is predominant in Juina Provence but rarely dodecahedral and octahedral crystals were found. In Diamantina and Espigao Dþoeste. Diamonds with dodecahedral habits are predominant. In the Juina kimberlitic province the infrared analysis have shown a high amount of type IIa (15%), type Iab (20%) and type IaAB (65%) diamonds, the last type bearing high nitrogen aggregation. Cacoal, Espigão Dfoeste and Diamantina diamonds were classified as IaAB type showing variations in the nitrogen aggregate state. Ultraviolet analysis showed different fluorescence colors for each province caused by variable rare-earth elements concentrations... (Complete abstract, click electronic access below)

Orientador: Vitor Baranauskas / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-10T13:04:37Z (GMT). No. of bitstreams: 1 Pinto_MarcioAugustoSampaio_M.pdf: 3334021 bytes, checksum: e3031df53e18ad072ffc8cbe1486889f (MD5) Previous issue date: 2007 / Resumo: Apresentamos neste trabalho o desenvolvimento de filmes de diamante crescidos com adição de enxofre. Foram crescidos por deposição química a partir da fase vapor (diamante CVD) utilizando reatores do tipo filamento quente. Para a obtenção de diamante com condução do tipo-n, diluímos diferentes concentrações de dissulfeto de carbono (CS2) em etanol, cujo vapor foi arrastado para o reator pelo hidrogênio. Isto foi feito, pois o enxofre pode agir como doador em diamante. A espectroscopia Raman mostrou a boa qualidade dos filmes de diamante crescidos mesmo com o aumento da concentração de CS2. Ocorreu o deslocamento do pico do diamante indicando que houve um aumento médio nos comprimentos das ligações detectadas nas amostras, possivelmente devido à expansão da rede do diamante pela incorporação do enxofre. As imagens revelam uma perda da cristalinidade das amostras intermediárias e o ótimo facetamento das amostras iniciais e finais (baixa e alta concentração de CS2). Medidas elétricas pela sonda de quatro pontas revelaram que quanto mais o CS2 era adicionado, mais a resistividade dos filmes produzidos diminuía e que depois voltou a subir nas últimas amostras. Ao tratar as amostras com ácidos nítrico e sulfúrico para fazer medidas por efeito Hall, elas se tornaram isolantes. Esse fato revela que o banho removeu o material condutor e que pode ser devido à dopagem com enxofre nas áreas superficiais e intergranulares dos filmes. Medidas por efeito Hall de amostras que foram crescidas ao mesmo tempo das amostras tratadas pelo banho, mas sem passar por ele, apresentaram uma condução do tipo-p devido aos buracos, da mesma forma que as amostras relatadas em artigos na literatura em que não houve contaminação com boro, seja ela involuntária ou voluntária. Apresentaram também alta densidade de portadores e uma mobilidade razoável. A incorporação do enxofre no filme de diamante foi confirmada por medidas de XRF e de PIXE. O aumento do enxofre incorporado no filme não foi proporcional às crescentes concentrações de CS2. Isto sugere que nem todo átomo de enxofre é eletricamente ativo, isto é, nem todo enxofre age como um dopante nos filmes de diamante. Estudos recentes revelam que a presença do boro nas dopagens com enxofre têm sido decisiva na obtenção de diamante do tipo-n / Abstract: We present in this work the development of grown diamond films with sulphur addition. They had been grown by chemical deposition from the vapor phase (diamond CVD) using reactors of the type hot filament. For the diamond attainment with conduction of the n-type, we diluted different concentrations of carbon disulfide (CS2) in ethyl alcohol, whose vapor was dragged into reactor by hydrogen. This was done, due to the fact that sulphur can act as a donor in diamond. The Raman spectroscopy showed exactly the good quality of the grown diamond films with the increase of the CS2 concentration. The displacement of the peak of the diamond occurred indicating that it had an average increase in the lengths of the linkings detected in the samples, possibly due to the expansion of the lattice of the diamond for the incorporation of sulphur. The images presented to a loss of the crystallinity of the intermediate samples and the excellent good crystalline facets of the initial and final samples (low and high concentration of CS2). The electric measures in four-point probe methods showed that the higher the concentration of CS2 the lower the resistivity of the produced films was, and afterwards, it went up again in the last samples. When treating the samples with nitric and sulphuric acids to make the measures for Hall effect, they had become insulators. This fact discloses that the bath removed the conducting material and that can be due to doping with sulphur in the surface and intergrain areas of the films. The Hall effect measures of the samples that had been grown at the same time of the samples treated for the bath, but without being through it, presented a conduction of the p-type due to the holes, in the same way that the samples described in articles in literature where they did not have contamination with boron, either involuntary or voluntary. They had also presented high density of carriers and a reasonable mobility. The incorporation of sulphur in the diamond film was confirmed by measures of XRF and PIXE. The increase of sulphur incorporated in the film was not proportional to the increasing concentrations of CS2. This suggests that nor all sulphur atom is electrically active, that is, not every sulphur acts as a dopant in the diamond films. Recent studies have disclosed that the presence of boron in the doping with sulphur has been decisive in the diamond attainment of the n-type / Mestrado / Eletrônica, Microeletrônica e Optoeletrônica / Mestre em Engenharia Elétrica

Orientador: Vitor Baranauskas / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-11T10:03:42Z (GMT). No. of bitstreams: 1 Roos_Mathias_M.pdf: 4816472 bytes, checksum: 51a357faa29ccbd01723b1d6ca5abf27 (MD5) Previous issue date: 2007 / Resumo: Na primeira parte deste trabalho amostras de diamante poli-cristalino dopado com boro foram crescidas por deposição química a vapor assistida por filamento quente. As características de emissão de campo foram investigadas. A dopagem (NB) em amostras diferentes foi variada pelo controle da concentração B/C no fluxo de gases durante o processo de crescimento. Os campos limiares (Eth) para emissão de campo foram medidos e relacionados com as concentrações B/C usadas. Assim, a influência das bordas entre os grãos, a dopagem e a morfologia da superfície na emissão de campo foram investigadas. A saturação da dopagem foi observada para altas concentrações B/C. O transporte de cargas através das bordas entre os grãos e as propriedades locais de emissão na superfície foram modeladas por dois mecanismos que afetam a emissão de campo. Correntes de emissão de 500 nA·cm-2 foram obtidas para campos elétricos de 8 V·µm-1. Na segunda parte desta tese, a construção de um novo sistema de ultra alto vácuo (UHV) para realizar medições de emissão de campo é descrita. A construção inclui o projeto integral de uma câmara de UHV com sistema de bombas, conjunto de manipuladores, suportes mecânicos e a infraestrutura do laboratório / Abstract: In the first part of this thesis, the study of field emission properties of hot filament chemical vapor deposited boron doped polycrystalline diamond is described. The doping level (NB) of different samples was varied controlling the B/C concentration in the gas feed during the growth processes. The threshold field (Eth) for electron emission in dependence on different B/C concentrations was measured and the influence of grain boundaries, doping level and surface morphology on the field emission properties was investigated. For high B/C ratios doping saturation was observed. Carrier transport through conductive grains and local emission properties of surface sites figured out to be two independent limiting effects on field emission. Emitter currents of 500 nA·cm-2 were obtained using electric fields less than 8 V·µm-1. In the second part the construction of a new UHV system for field emission measurements is described, including the complete project of a UHV chamber with pump system, manipulators and sample transfer system, mechanical supports and the infrastructural requirements of the laboratory / Mestrado / Eletrônica, Microeletrônica e Optoeletrônica / Mestre em Engenharia Elétrica

Analog and digital structures can be written into thin surface layers of semiconductors by using focused ion beams of submicron dimensions. By inducing the phase transition from the crystalline (c) to the amorphous state (a) optical contrast is generated between areas of different exposure. The aim of this study was to investigate the properties of diamond as a high-density optical recording medium and to determine the corresponding irradiation parameters. To this end, single crystals of diamond were irradiated with self-ions of 75 key energy with fluences between F=0.3-l0xlO15 C/cm2 at about 100 K. The radiation damage, persisting after annealing treatments between 300-1700 K, was studied by Raman measurements, monitoring changes in the atomic bonding arrangements. Since the scattering cross-section of C sp2 bonds is 50x that of C sp3 bonds, this is an extremely sensitive technique in detecting changes in the initially purely sp3 state. The position and linewidth of the characteristic first-order phonon of crystalline diamond at 1332 cm-l reflect crystallinity and stress level, while bands between 1350-1700 cm-l indicate disorder. In utilizing the microscopic resolution of a Raman facility additional information was obtained on the spatial variation of the damage level. The optimum annealing temperature was found to be 1500 K. For F > 3xlO15C/cm2, the damage was irreversible, for F = 3xlO15C/cm2 the damage was only partly repaired after annealing at 1500 K and, for F < 3xlO15C/ cm2, the crystalline/amorphous contrast was reversible. For F < lxl015C/ cm2 Raman spectroscopy was not sensitive enough to detect the incurred damage. Infrared spectroscopy was used to classify the diamond samples according to type. / Dissertation (MSc (Chemistry))--University of Pretoria, 2006. / Chemistry / unrestricted

The goal of this master thesis is a complex description of blood diamonds issues and assessment of existing efforts, specific steps and presented ideas, conceptions and strategies on the ground of Kimberley Process, as well as suggestions of possible solutions and future steps of organizations like Global Witness, Partnership Africa Canada, Human Rights Watch and other interested groups fighting against occurence of illicit diamonds. The thesis is divided into 4 chapters. The first chapter describes characteristics and significance of diamonds. The second chapter focuses on organizations agitating against blood diamonds in the world. The third chapter is subsequently designated for definition and features of the term of failed state, which is often highly connected with the blood diamonds issue. The fourth chapter analyses concrete conflicts or illegal activities in Angola, Sierra Leone, Liberia, Democratic Republic of Congo, Côte d'Ivoire, Republic of Congo and Zimbabwe.

Sexual violence has been a considered tragic yet inevitable part of most armed conflicts throughout history. Various connections have been made between natural resources and conflict-related sexual violence and this paper aims to explore this relationship further. This study uses theory on lootable natural resources and sexual violence to hypothesize that lootable natural resources, compared to unlootable, will affect the likelihood of sexual violence. The proposed hypothesis is that rebels who extort alluvial diamonds, a lootable resource, are more likely to engage in sexual violence. Using data from the SVAC and the RCD datasets, the hypothesis is tested through logistic regression. The empirical analysis show that the effect of diamond extortion is indeed statistically significant, which supports the hypothesis. These results contribute to finding possible predictors of conflict-related sexual violence, to help prevent further victims of this violence.

Examples of state and non-state actors collaborating on issues of global politics abound. Non-state actors are increasingly involved in policy formulation processes, in peace-keeping processes, in human rights and environmental issues by advising governments or inter-governmental organisations. This type of collaboration mostly takes place at the discretion of states. However, non-state actors sometimes appear to initiate diplomatic processes. The Kimberley Process is an example of such a case. States and another non-state actor, namely business, were forced to the negotiating table by NGOs who were effectively raising consumer awareness about the role of diamonds in fuelling conflict and who held the power over launching a possible consumer boycott. Polylateralism is a term that was coined to represent the participation of non-state actors in the conduct of international relations. The study uses the Kimberley Process negotiations from 2000 to 2002 as a case study to analyse the dynamics of polylateral diplomacy by examining the nature and form of interaction between the three sets of actors, namely states, civil society and business in order to understand the role played by each group in both agenda setting and rule making, and the extent to which their interactions conform to the central ideas of polylateralism as advanced by international scholars. In so doing the study examines the evolving mode of interaction between states and non-state actors in the Kimberley Process, the ability of non-state actors to influence diplomatic processes, the extent to which states determined the boundaries of non-state diplomatic involvement and, finally, the limitations of polylateral diplomacy. The study concludes that the apparent increase in collaboration between state and non-state actors in diplomatic processes does not constitute a new method of diplomacy and that this will not change until non-state actors have become recognised polities. It also finds that the involvement of non-state actors in diplomacy, particularly as consumers of diplomatic outcomes is likely to become more-and-more prevalent and that professional diplomats, especially those in developing countries, may have to adapt their working methods in order to benefit from this phenomenon by allowing for a more systematic engagement with non-state actors. Finally, it finds that while the Kimberley Process is a good example of the involvement of non-state actors as producers of diplomatic outcomes, this phenomenon is less likely to reoccur and may well be the exception rather than the rule for the foreseeable future. / Dissertation (MDiplomatic Studies)--University of Pretoria, 2011. / Political Sciences / unrestricted

This work is aimed at the understanding of the dynamical behavior of hydrogen in diamond. The investigation was carried out using Transverse Field muon Spin Rotation (TF-SR) and the Longitudinal Field muon Spin Relaxation (LF-SR) techniques. The chemical analogy between hydrogen (p+e-) and muonium (u+e-) enabled the study of the indirect dynamical behavior of hydrogen in diamond. The TF-SR and LF-SR measurements were carried out in an isotopically pure 13C diamond in the temperature ranges 11 mK - 320 K and 10 K - 400 K, respectively. In the TF-SR results, the Prompt Absolute Fraction (PAF) of both diamagnetic and the paramagnetic states are temperature independent. The spin relaxation rate for the state is non-zero and temperature independent, while that of the Mux state is non-zero and temperature dependent. The behavior of indicates that the u+d is immobile, while that of MuT indicates the mobility in diamond. The LF-SR results provide hop rate and associated nuclear hyperfine interaction parameters of the Mut state in diamond. / Physics / M.Sc. (Physics)