Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (leaves 99-107).

Th. doct.--Biochim.--Nantes, 1994. / Bibliogr. p. 257-275. Résumé en français et en anglais.

Universiẗat-Gesamthochsch., Diss., 1997--Paderborn.

Techn. Hochsch., Diss., 2004--Aachen.

Th.--Sci. phys.--Toulouse--I.N.P., 1985. N°: 100.

Thesis (Ph.D.)--Boston University / Lutetium oxide doped with europium oxide (Lu20 3:Eu3+) has been established to be a bright, dense scintillator materi al with vast potential in both medical and high resolution X-ray imaging applications. Unfortunately its commercial viability has been restricted due to the manufacturing and post treatment costs associated with device fabrication. This research was aimed at the development of two vapor deposition techniques; chemical and physical vapor deposition (CVD and PVD), to produce coatings of Lu203:Eu3+ for various X-ray imaging applications. A customized CVD process to codeposit Lu20 3 and Eu20 3 was developed using lutetium and europium chloride (LuCb and EuCI3) precursors and reacting with carbon dioxide (C02) and hydrogen (H2) . An in depth study was performed by systematically varying the process parameters to explore the deposition kinetics and identify the rate limiting steps and their effects on the growth morphology using both cold and hot wall CVD reactors. The activation energy for the kinetically limited deposition of Lu20 3 from the LuCI3 - Ar - C02 - H2 system was identified to be approximately 170 kJ/mol , which is significantly lower than expected. The predominant growth orientations were identified to be { 111} and { 100} , depending on the deposition conditions. As the temperature is increased, the growth orientation preference decreases to produce a randomly oriented growth at 1150°C. The scintillation and X-ray imaging characteristics of a co-deposited Lu203:Eu3+ thin film with a {100} orientation were measured, confirming the feasibility and applicability of the CVD system to produce thick scintillator x-ray imaging devices. A fundamental study of the PVD process was performed by sputtering of Lu203:Eu3+ using a single target magnetron sputtering gun. Systematic vatiations of the deposition parameters were used to understand the effect of the ejected flux kinetic energies and deposition rate on the deposit density, stress, optical and scintillation properties. The deposition system was subsequently optimized for rapid, dense growth of a 10 um thick Lu203:Eu3+ coating at elevated temperatures. The X-ray imaging properties were measured and the results yielded an X-ray imaging resolution slightly better than 1 um with the potential for 0.5 um with further optimization, a level never before attained.

SOUSA, Alexandre Carreira da Cruz. 5,10,15,20-meso-tetrapiridilporfirina de európio: síntese, caracterização e investigações espectroscópicas. 2015. 62. Dissertação (Mestrado em química)- Universidade Federal do Ceará, Fortaleza-CE, 2015. / Submitted by Elineudson Ribeiro (elineudsonr@gmail.com) on 2016-10-04T14:55:21Z No. of bitstreams: 1 2015_dis_accsousa.pdf: 1629715 bytes, checksum: 264276171b2e35ae1514203c752b6856 (MD5) / Approved for entry into archive by Jairo Viana (jairo@ufc.br) on 2016-10-10T19:42:17Z (GMT) No. of bitstreams: 1 2015_dis_accsousa.pdf: 1629715 bytes, checksum: 264276171b2e35ae1514203c752b6856 (MD5) / Made available in DSpace on 2016-10-10T19:42:17Z (GMT). No. of bitstreams: 1 2015_dis_accsousa.pdf: 1629715 bytes, checksum: 264276171b2e35ae1514203c752b6856 (MD5) Previous issue date: 2015 / Increasingly, porphyrins have gained a position of detached interest in scientific circles. Its high biological compatibility, being a molecule found naturally in plants and many red blood animals, coupled with the possibility of forming complexes with lanthanide atoms, makes these compounds are particularly attractive in a branch of medicine quite promising in terms respect to combat cancer, called photodynamic therapy. The lanthanide-porphyrin complex act as photosensitizers in the production of singlet oxygen, a cytotoxic species, may be soaked in organic tissue of interest, promoting the cancer cell death. The synthesis of some Ln-porphyrin complexes [Ln (Ln = Gd, Er, Yb)] are already reported in the literature. However, with increasing ionic radius of metal that is intended to complex in the porphyrin, the energy barrier which prevails opposite the occurrence of this synthesis also increases, hindering the occurrence of the metalation process. Thus, this study seeks to promote metalation with europium, in 5,10,15,20 - meso - tetrapyridilporphyrin (H2TPyP). Was used the europium acetylacetonate salt [Eu(acac)3] in the synthesis as a source of Eu3+ ion. The obtained compound was purified by column chromatography on elution of alumina (Al2O3) and further characterized by absorption spectroscopy in the ultraviolet-visible region (UV-VIS) and infrared region (IR), luminescence and termogravimetric analysis (TG). The results obtained for the UV-vis spectra show for complex synthesized 3 Q bands, a lower number compared to the spectrum of the free base porphyrin, which has 4 Q bands, which discloses the formation of a compound with higher symmetry, which rose from D2h to D4h due to insertion of the metal ion in the porphyrin ring. It was observed also a bathochromic shift of the Soret band in the complex shifted from 417 to 429nm, consistent with the fact that the metallation occurred. The IR results and suggest the occurrence of metalation of the suppression band 3304cm-1, indicating deprotonation of the central atoms of Nytrogen, also suggested maintaining the acetylacetonate ion in stabilizing the structure of the complex. The luminescence showed that there was enhancement of emission bands, which is consistent with the formation of a metal complex. In the TG results, it was found that the compound formed to the amount of residue obtained was much higher than that for H2TPyP, suggesting the formation of metal oxide in the first case, consistent with the fact that formation of europium metalloporphyrin. / Cada vez mais, as porfirinas vêm conquistando uma posição de destacado interesse no meio científico. Sua elevada compatibilidade biológica, sendo uma molécula encontrada naturalmente em plantas e em diversos animais de sangue vermelho, aliada a possibilidade da formação de complexos com átomos de lantanídeos, faz com que esses compostos sejam particularmente atrativos em um ramo bastante promissor da medicina no que diz respeito ao combate ao câncer, denominado de terapia fotodinâmica. Isso porque os complexos lantanídeos-porfirina atuam como fotossensibilizadores na produção de oxigênio singlete, uma espécie citotóxica, podendo esses complexos serem saturados em tecidos orgânicos de interesse, promovendo a morte de células cancerígenas. A síntese de alguns complexos Ln-porfirina (Ln= Gd, Er, Yb) já são reportadas na literatura. Entretanto, com o aumento do raio iônico do metal que se pretende complexar a porfirina, a barreira energética que se impera frente a ocorrência desta síntese também aumenta, dificultando a ocorrência do processo de metalação. Dessa forma, o presente estudo busca promover a metalação de európio na 5,10,15,20 – meso – tetrapiridilporfirina (H2TPyP). Utilizou-se o sal acetilacetonato de európio [Eu(acac)3] na síntese como fonte do íon Eu3+. O composto obtido foi purificado por eluição em coluna cromatográfica de alumina (Al2O3) e posteriormente caracterizado por espectroscopia de absorção na região do ultravioleta-visível (UV-Vis) e infravermelho (IR), luminescência e análise termogravimética (TG). Os resultados obtidos por UV-Vis para o complexo sintetizado mostraram espectros com 3 bandas Q, um menor número comparado ao espectro da porfirina base livre que apresenta 4 bandas Q, o que sugere a formação de um composto com maior simetria, que passou de D2h para D4h, devido a inserção do íon metálico no anel porfirínico. Observou-se também um deslocamento batocrômico da banda Soret no complexo que deslocou de 417 para 429nm, fato condizente com a ocorrência da metalação. Os resultados de IR, além de sugerirem a ocorrência da metalação pela supressão da banda em 3304cm-1, indicando a desprotonação dos nitrogênios centrais, também sugeriram a manutenção do íon acetilacetonato na estabilização da estrutura do complexo. A luminescência mostrou que houve intensificação das bandas de emissão, o que condiz com a formação de um complexo metálico. Nos resultados de TG constatou-se que para o composto formado a quantidade de resíduo obtido foi bastante superior de que para a H2TPyP, sugerindo a formação de óxido metálico no primeiro caso, fato condizente com a formação da metaloporfirina de európio.

Made available in DSpace on 2014-06-11T19:25:33Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-03-06Bitstream added on 2014-06-13T20:53:37Z : No. of bitstreams: 1 saliba_lf_me_ilha.pdf: 2689127 bytes, checksum: 77157443fa70337c82aeb80e43ec516e (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A sílica mesoporosa do tipo MSU-4 foi sintetizada a partir do agente direcionador de estrutura Tween 20, utilizado como molde, e do precursor inorgânico tetraetilortosilicato (TEOS). Estruturas mesoporosas tem sido aplicadas em estudos luminescentes por apresentarem alto índice de organização, grande área superficial e distribuição regular de tamanho de poros. Nesse trabalho a sílica mesoporosa foi funcionalizada com 3-aminopropiltrietoxisilano (APTES) para aplicação luminescente. A sílica mesoporosa funcionalizada foi caracterizada por difração de raios-X a baixo ângulo (SAXS), espectroscopia no infravermelho (FT-IR) e adsorção e dessorção de nitrogênio (BET). O material luminescente foi preparado pela formação do complexo [Eu(tta)3] em meio metanólico e impregnado nos canais da sílica mesoporosa. Para a impregnação, o íon Eu3+ foi primeiramente encapsulado na sílica e posteriormente foi adicionado o ligante 2- tenoiltrifluoroacetona (tta). Esse procedimento foi realizado para as sílicas lavada, calcinada e funcionalizada. Uma amostra de sílica funcionalizada foi preparada com a impregnação do complexo já pronto. Todas as amostras foram caracterizadas por espectroscopia luminescente. O estudo espectroscópico foi realizado à temperatura ambiente e os espectros de excitação mostraram a absorção de energia pelo ligante tta na faixa do ultravioleta. Os espectros de emissão mostraram as transições características do íon Eu3+, dos estados de maior energia 5D0 para os de menor energia 7F0-4. Foi observado que a transferência de energia do ligante para o íon Eu3+ foi eficiente. A transição hipersensitiva 5D0→7F2 mostrou o efeito das diferentes superfícies da matriz de sílica. PALAVRAS CHAVE: Sílica mesoporosa, luminescência, európio. / MSU-4 type mesoporous sílica has been synthesized with polyoxyethylenesorbitan monolaurate (Tween 20) as structure-directing agent (MTS) as a template and tetraethyl orthosilicate Si(OEt)4 (TEOS) as silica source. The mesoporous structures have a wide application in the luminescence study because of their organization, large surface area, and size of pores. In this work, MSU-4 mesoporous silica was functionalized with 3-amino-propyl-triethoxysilane (APTES) for luminescence applications. Mesoporous silica and amino-functionalized silica was characterized by small-angle X-ray scattering (SAXS), infrared spectroscopy (FT-IR) and nitrogen adsorption/desorption isotherms at 77 K (BET). A luminescent material was prepared by formation of the complex Eu(tta)3 in methanolic medium within the channels of MSU-4 type ordered mesoporous silica. Using simple wet impregnation methods, the europium ion was first encapsulated followed by ligand 2-thenoyltrifluoracetonate (tta) addition. This process it was done for washed, calcined and functionalized mesoporous silica. Analogous one sample of functionalized silica was impregnated with the complex already ready. All samples were characterized by photoluminescence spectroscopy. The spectroscopy studies in room temperature showed the energy absorption of the ligand range ultraviolet in excitation spectra. The emission spectra this materials displayed the typical Eu3+ intra-4f6 lines ascribed to transitions between the 5D0,1 excited states and the ground multiplet (7F0-4). Negligible emission from the organic part of the encapsulated species was observed, indicating that energy transfer from the ligands to the Eu3+ ion was quite efficient. The hypersensitive 5D0→7F2 line showed the mesoporous silica effect in luminescence europium chelate.

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Made available in DSpace on 2014-10-09T12:28:07Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:01:37Z (GMT). No. of bitstreams: 0 / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP