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Monteiro, Jorge Henrique Santos Klier 1985. "Propriedades fotofísicas de complexos de íons lantanídeos no estado sólido e em solução aquosa : imageamento e atividade citotóxica." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/250268.
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Orientadores: Fernando Aparecido Sigoli, André Luiz Barboza FormigaTese (doutorado) - Universidade Estadual de Campinas, Instituto de Química
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Resumo: Neste trabalho sintetizaram-se os ligantes 4-azidadipicolinato (dipicN3), 4-aminodipicolinato (dipicNH2) e 4-aminopiridina-bis(oxazolina) (pyboxNH2), bem como seus complexos com íons lantanídeos(III) solúveis em água. Sintetizaram-se também complexos insolúveis em água, contendo ligantes derivados dos ácidos benzóico, fenilselenínico e fenilfosfínico. A coordenação dos complexos foi verificada utilizando espectroscopia de absorção no infravermelho, enquanto que a estequiometria dos complexos foi confirmada utilizando análise elementar de carbono e hidrogênio, titulação complexométrica, espectrometria de massas e 1H-RMN. Também foram obtidas as estruturas de alguns complexos por difração de raios X de monocristal. Com os complexos análogos de gadolínio(III) foram obtidos os espectros de fosforescência do ligante a ?77 K com resolução temporal para determinação da energia do nível tripleto, a qual foi obtida pelo método da tangente ou da transição 0-0 fônon. Os complexos de európio(III) foram classificados, comparativamente, em função da simetria pontual, utilizando os espectros de emissão, parâmetros de intensidade de Judd-Ofelt e razão assimétrica, e também em função do grau de covalência da ligação Eu ¿ O, obtido pelo baricentro da transição 5D0 ? 7F0. Foi também medido o tempo de vida de emissão e o rendimento quântico dos complexos contendo os íons európio(III) ou térbio(III). As geometrias do estado fundamental foram determinadas utilizando o método Sparkle/PM3, sendo assim possível explicar alguns dos resultados experimentais obtidos, tal como a alta eficiência de sensitização de alguns complexos. Os complexos de európio(III) e térbio(III) com os ligantes dipicN3, dipicNH2 e pyboxNH2 apresentaram luminescência em solução aquosa, tempo de vida > 1 ms e rendimento quântico na faixa 15 ¿ 40 %, qualificando-os como marcadores luminescentes em sistemas biológicos. Os ligantes e seus complexos tiveram suas citotoxicidades testadas contra células normais (NIH/3T3) e células neoplásicas (NG97, câncer de cérebro e PANC1, câncer de pâncreas). Somente os complexos apresentaram atividade citotóxica e esta é seletiva para células NG97 e PANC1. O complexo K3[Eu(dipicNH2)3] foi capaz de atravessar a barreira hemato-encefálica e foi utilizado como marcador luminescente para células NG97 e PANC1
Abstract: Water-soluble lanthanide complexes with the ligands 4-azidodipicolinate (dipicN3), 4-aminodipicolinate (dipicNH2) and 4-aminopyridine bis-oxazoline (pyboxNH2) were synthesized, a long with water-insoluble lanthanide complexes with ligands derived from benzoic, phenylseleninic or phenylphosphinic acids. The coordination modes of the carboxylic ligands were verified by FT-IR. The stoichiometries of the complexes were confirmed by carbon and hydrogen elemental analysis, complexometric titration and mass spectrometry. The crystal structures of some complexes were determined by single crystal X-ray diffraction. The time-resolved phosphorescence spectra of the ligands were obtained at ?77 K using the gadolinium(III) analogs complexes in order to obtain the energies of triplet levels. The triplet energies were determined by the tangent method or the 0-0 phonon transition. The europium(III) complexes were classified, comparatively, as a function of the point symmetry, using the emission spectra, Judd-Ofelt intensity parameters and the asymmetric ratio, and as a function of the Eu ¿ O bond covalence degree, obtained from the centroid of the 5D0 ? 7F0 transition. The emission lifetimes and quantum yields for the europium(III) and terbium(III) complexes were also determined. The ground state geometries were calculated using the Sparkle/PM3 method and were used to explain some of the experimental results such as the high sensitization efficiency of some complexes. The europium(III) and terbium(III) complexes with the ligands dipicN3, dipicNH2 and pyboxNH2 showed luminescence in water, emission lifetimes > 1 ms and quantum yields in the range 15 ¿ 40 %, qualifying them as potential luminescent markers for biological systems. Cytotoxic assays using the ligands and their complexes against normal cells (NIH/3T3) and neoplastic cells (NG97, brain¿s cancer and PANC1, pancreatic cancer) were performed. Only the complexes showed selective cytotoxicity against NG97 and PANC1 cells. The complex K3[Eu(dipicNH2)3] was able to cross a simulated blood-brain barrier and was also used as a luminescent marker for NG97 and PANC1 cells
Doutorado
Quimica Inorganica
Doutor em Ciências
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Werts, Martinus Henricus Valentinus. "Luminescent lanthanide complexes visible light sensitised red and near-infrared luminescence /." [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2000. http://dare.uva.nl/document/83075.
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Macario, Leilane Roberta [UNESP]. "Efeito das terras raras nas propriedades óticas do BaM'O.IND.3'(M==Zr, Ti)." Universidade Estadual Paulista (UNESP), 2010. http://hdl.handle.net/11449/97886.
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macario_lr_me_araiq.pdf: 2041175 bytes, checksum: 961d5ba845b7c11a8a6b7a00c583a3b4 (MD5)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
A necessidade de materiais com emissão luminescente tem aumentado continuamente com o desenvolvimento tecnológico. Para isto, torna-se necessária a obtenção de novos materiais, a fim de acompanhar esta crescente demanda. A criação de novos dispositivos depende, em geral, da obtenção de materiais que possam ser sintetizados, sem que haja a necessidade de utilização de condições especiais de síntese. Com isso, neste trabalho foram obtidas estruturas cristalinas de titanatos e zirconatos de bário dopados com a terra rara európio (Eu) por intermédio do método Hidrotérmico Assistido por Micro-ondas (HAM). Foram utilizadas as técnicas de caracterização, Difração de Raios X (DRX), Microscopia Eletrônica de Varredura (MEV), Espectroscopia Raman (FT-Raman), Espectroscopia de Reflectância no Ultravioleta e Visível (UV-Vis) e Fotoluminescência (FL), com intuito de verificar a influência do dopante Eu sobre as características ópticas e estruturais nos materiais. Assim, foi realizado um estudo correlacionando as técnicas de caracterização que permitiram uma avaliação das propriedades fotoluminescentes e da organização estrutural destes materiais. Os espectros de DRX mostraram que ambos os compostos podem ser obtidos, na fase cristalina a partir de um minuto de tratamento em HAM, sendo o zirconato de bário (BZ) de fase cúbica e o titanato de bário (BT) de fase tetragonal. A espectroscopia Raman foi uma ferramenta importante para caracterizar os compostos a curta distância de acordo com os tempos de síntese das amostras e da concentração de Eu. Por intermédio das medidas de UV-Vis verificou-se a presença de estados intermediários na região do “gap” gerados por defeitos estruturais nos compostos e a inserção dos íons Eu3+ nas redes cristalinas de BZ e BT. Os materiais sintetizados quando excitados em 350,7 nm apresentaram emissões de banda larga na região...
The need for materials with luminescence increases with technological development, which grows every day. For this, it becomes necessary the obtention of new materials in order to follow this growing demand. The creation of new devices depends, in general, from obtaining materials that can be synthesized without the need to use special conditions of synthesis. Thus, in this work crystal structures of barium titanate and barium zirconate doped with rare earth europium (Eu) were obtained through the hydrothermal method assisted by microwave (HAM). The characterization techniques used were X-Ray Diffraction (XRD), Scanning Electron Microscopy (EMS), Raman Spectroscopy (FT-Raman), Reflectance Spectroscopy on Ultraviolet and Visible (UV-Vis) and Photoluminescence (FL), in order to verify the influence of doping on the synthesized materials. Thus, a study correlating the characterization techniques that have allowed an evaluation of the photoluminescent properties and structural organization of these materials was necessary. XRD spectra showed that both materials can be obtained in crystalline phase from one minute of treatment on HAM, giving barium zirconate (BZ) in cubic phase and barium titanate (BT) in tetragonal phase. Raman spectroscopy has been an important tool to characterize the compounds in short distance according to the time of synthesis and Eu concentrations. By means of UV-Vis measurements the presence of intermediate states were observed in the region of gap generated by structural defects in the compounds and the insertion of Eu3+ ions in the crystalline lattice of BZ and BT. The synthesized materials, when excited at 350.7 nm, showed a broadband emission in the visible region, with a variation of intensity of broad bands relative to the luminescence of the matrices by varying the concentration of Eu3+, as well as intensity variations on emissions from the rare earth in question... (Complete abstract click electronic access below)
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Kallir, Alan J. "Total luminescence spectroscopy /." [S.l.] : [s.n.], 1986. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=7960.
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Xu, Jin. "Luminescence in ZnO." VCU Scholars Compass, 2004. http://hdl.handle.net/10156/1444.
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Fox, D. B. "Sensing WIT luminescence." Thesis, Queen's University Belfast, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246538.
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Scholefield, Roger. "Luminescence of quartz /." Title page, contents and summary only, 1994. http://web4.library.adelaide.edu.au/theses/09SM/09sms3678.pdf.
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Alves, Raphael Henrique de Carvalho. "Aplicação da técnica de luminescência opticamente estimulada em fototerapia para determinar a energia entregue em meios iluminados com laser ou LED nas faixas do vermelho e infravermelho." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-16012017-110450/.
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Alguns ramos da Medicina vêm empregando lasers ou LEDs de baixa potência em diversas especialidades. Estes lasers e LEDs são classificados como luz de baixa potência (LBP) e são usados na área de Fototerapia com comprimentos de onda na faixa do vermelho e do infravermelho. Por outro lado, a área de dosimetria utiliza dispositivos (dosímetros) capazes de estimar a energia depositada devido a exposição prévia à radiação ionizante usando luz visível como estímulo para obtenção de um sinal luminoso - esta técnica é a luminescência opticamente estimulada (OSL). O objetivo deste trabalho é avaliar a possibilidade de estimar a energia entregue por iluminação com laser e LED de baixas potências com comprimentos de onda na faixa do vermelho e infravermelho, utilizados na Fototerapia, empregando a dosimetria OSL. Foram empregados dosímetros de óxido de alumínio, óxido de berílio e fluorita natural, irradiados previamente com radiação beta (dose absorvida de aproximadamente 50 mGy), e iluminados com laser de 658 nm ou LED de 870 nm. Utilizamos o laser com potências de 10, 20, 50 e 100 mW, na faixa de energias de 0,1 a 13,2 J, e os LEDs com potências de 14,5, 58,0 e 130,5 mW, com faixa de energia entre 0,2 e 23,5 J. Para a medida de OSL foi utilizado o leitor TL/OSL Risø (modelo TL/OSL-DA-20) no modo de leitura CW-OSL e estimulo com LED de luz azul de 72 mW. A análise das curvas de emissão OSL foi feita observando tendências na modificação do sinal inicial OSL (integrado no primeiro 1s de leitura) e no sinal OSL total (integrado em 100 s) normalizados por sinal OSL obtido para irradiação padronizada. Os resultados obtidos mostraram que a iluminação com laser de 658 nm reduz o sinal OSL das amostras de óxido de alumínio para energias entre ~0,1 e ~12 J, e o sinal OSL de fluorita em uma faixa de energias mais baixa, entre ~0,1 e ~4 J. Para a iluminação com LED de 870 nm somente as amostras de fluorita mostraram redução do sinal OSL, no intervalo de ~0,1 e ~15 J de energia luminosa incidente; essa mudança foi mais acentuada para o sinal inicial da curva OSL do que para o sinal integrado. As mudanças observadas são independentes das potências luminosas empregadas. As amostras de óxido de berílio não mostraram mudanças na emissão OSL para nenhum dos feixes de luz no intervalo de energia utilizados. Além destes resultados também foi observado que a iluminação com diferentes energias luminosas incidentes nas amostras muda o formato das curvas de emissão OSL das amostras de fluorita: o tempo característico de decaimento das curvas de emissão cresce à medida que mais energia luminosa (infravermelho) é depositada nas amostras. Os resultados mostraram que a técnica OSL poderia ser utilizada para a avaliar de energia luminosa incidente no óxido de alumínio, iluminado com laser de 658 nm, e na fluorita natural, iluminada com LED de 870 nm. Para a fluorita, a mudança nas curvas de emissão OSL das amostras também pode estar relacionada com a energia luminosa incidente nela, fato que deverá ser mais bem estudado em trabalhos posteriores.Some branches of Medicine are using low power lasers and LEDs in various specialties. These devices are classified as low-power or low-level lasers and LEDs and they are used in phototherapy in the red and infrared wavelength range. On the other hand, in dosimetry some devices (dosimeters) are used to estimate the deposited energy due to a previous exposure to ionizing radiation through a visible light stimulus to get a light signal - this technique is the optically stimulated luminescence (OSL). The objective of this study is to evaluate the possibility of assessing the energy delivered by illumination with laser and LED in the red and infrared wavelength ranges, used in the phototherapy, using the OSL technique. OSL dosimeters of aluminum oxide, beryllium oxide and natural fluorite were used. They were previously exposed to beta radiation (absorbed dose of about 50 mGy) and illuminated with 658 nm laser or 870 nm LED. The laser powers were 10, 20, 50 and 100 mW, and the light energy was in the range 0.1 to 13.2 J; and the chosen LED powers were 14.5, 58.0, 130.5 mW, delivering energies in the range 0.2 to 23.5 J. The OSL emission curves were measured with the TL/OSL Risø (TL/OSL-DA-20 model), CW-OSL mode, stimulating light provided by blue LEDs of 72 mW. The analysis of the OSL curves was carried out through the observation of trends in the variations of initial OSL signal (integrated in the first 1 s) and the whole OSL signal (integrated in 100 s) normalized by an OSL signal due to a standard irradiation. The results showed that the illumination with 658 nm laser reduces the OSL signal from aluminum oxide samples in the energy range between ~0.1 and ~12 J, and from fluorite in the energy range from ~0.1 to ~4 J. For the 870 nm LED illumination, only fluorite samples showed a reduction in the OSL signal in the range from ~ 0.1 to ~ 15 J of incident light energy. This change was more pronounced for the initial OSL signal than for the integrated signal. The observed changes were independent of the light power used in the illumination. The OSL signal of beryllium oxide samples showed no changes for any of the light beams used. It was also observed that illumination with different incident light energy changes the shape of fluorite OSL curves. The characteristic decay time of the emission curves grows as the light energy (infrared) deposited on the samples of fluorite increases. The results showed that the OSL technique could be used to evaluate the light energy incident on aluminum oxide, illuminated with 658 nm laser, and on fluorite, illuminated with 870 nm LED. For fluorite samples, the change in the OSL emission curve can also be related to the incident light energy. This fact needs further studies for a better understanding.
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Vorpagel, Andreia Jaqueline [UNESP]. "Híbridos orgânicos-inorgânicos siloxanos àcidos-graxos emissores de luz branca." Universidade Estadual Paulista (UNESP), 2012. http://hdl.handle.net/11449/97928.
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vorpagel_aj_me_araiq_parcial.pdf: 100014 bytes, checksum: 4564e5ec816f9efbc700fa94c80a40c4 (MD5)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Novos compósitos híbridos orgânicos-inorgânicos foram preparados pela incorporação de nanopartículas de fórmula geral YVO4 dopada com os lantanídeos Yb/Er, Yb/Tm e Yb/Ho em matrizes híbridas do tipo “amidosil”, obtidas da reação de ácido ricinoleico (AR) e 3-aminopropiltrietoxisilano (APTES). Os materiais foram caracterizados por espectroscopia de absorção no infravermelho, difração de raios X, microscopia eletrônica de transmissão e espectroscopia eletrônica. Estas partículas de vanadato de ítrio dopadas com lantanídeos, sob excitação no infravermelho (980 nm) emitem luz na região do visível em diferentes comprimentos de onda, devido a mecanismo de conversão ascendente de energia. A união nanopartículas e híbrido permitiu obter novos materiais híbridos emissores de luz branca, graças a um ajuste fino na relação matriz/partícula
New composite organic-inorganic hybrid compounds were prepared by the incorporation of nanoparticles of general formula YVO4:Ln3+ (Ln= Yb/Er, Yb/Tm, Yb/Ho) in amidosil hybrids obtained from the reaction of ricinoleic acid (RA) and 3-aminopropyltriethoxysilane (APTES). The materials were characterized by infrared absorption spectroscopy, x-ray diffraction, scanning and transmission electron microscopy. Under infrared excitation (980 nm) vanadate nanoparticles emit visible light of different colors due to mechanism energy by up conversion energy transfer. The addition of variable relative contents of the nanoparticles into the hybrid host allowed different emission colors to be observed resulting the white
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Romero, João Henrique Saska [UNESP]. "Efeito de compensação de cargas nas propriedades luminescentes dos materiais 'BA''WO IND.4':'EU POT.3+','LI POT.+'." Universidade Estadual Paulista (UNESP), 2013. http://hdl.handle.net/11449/97930.
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romero_jhs_me_araiq.pdf: 6526323 bytes, checksum: 620b6c7ea0965ec08f4b26b138f3866c (MD5)As propriedades luminescentes, assim como a luminescência com excitação por raios X (XEOL) dos compostos Ba1-xEuxWO4, Ba1-3xEu2xWO4 e Ba1-2xEuxLixWO4 foram comparadas. As amostras foram obtidas pelo método Pechini com diferentes concentrações de dopante, diferentes atmosferas (mistura verde, argônio ou estática de ar) e temperaturas de tratamento térmico das amostras. BaWO4 forma compostos de estrutura tetragonal tipo Scheelita pertencentes ao grupo espacial I41/a. A substituição de íons Ba2+ por íons Eu3+ fornece dados importantes sobre a estrutura e a microssimetria do íon lantanídeo na matriz. Uma alternativa de compensação de carga com a introdução de Eu3+ no retículo do BaWO4 é a codopagem Li+/Eu3+. Neste sistema, dois cátions Ba2+ são substituídos, gerando a compensação de carga, resultando em propriedades luminescentes únicas. As amostras BaWO4, Ba1-xEuxWO4, Ba1-3xEu2xWO4 e Ba1-2xEuxLixWO4 (x = 1, 3 e 5% em mol) foram tratadas termicamente a 700, 900 e 1100º C e caracterizadas pelas técnicas de difração de raios X (XRD), espectroscopia de espalhamento Raman (RAMAN), espectroscopia vibracional de absorção na região do infravermelho (FTIR), microscopia eletrônica de varredura (SEM), índice de cor (CIE-Lab), espectroscopia de reflectância difusa (DRS), espectroscopia de fotoluminescência (PL), espectroscopia de luminescência com excitação por raios X (XEOL). As medidas XEOL foram realizadas no Instituto de Química Campus Araraquara. Todas as amostras apresentaram o mesmo perfil de difração, independentemente da concentração de dopante (máximo de 10%, Eu3+,Li+). A fase Scheelita (JCPDS-PDF nº 43-646) foi constatada. As exceções são as amostras BaWO4:Eu3+,Li+ dopadas com 1:1 e 3:3%, tratadas a 700 e 900 °C, que possuem baixa cristalinidade...
Luminescent properties, including X-ray excited optical luminescence (XEOL) of compounds Ba1-xEuxWO4, Ba1-3xEu2xWO4 and Ba1-2xEuxLixWO4 were compared. Samples were prepared by the Pechini method according to different dopand concentrations, different atmosphere (green mixture, argon and static air) and temperature during the thermal treatment of samples. Scheelite tetragonal structures of BaWO4 belongs to the space group I41/a. The Eu3+ substitutes for Ba2+ ions can provide important data on the structure and micro symmetry of lanthanide ions in the host lattice. An alternative way to charge compensation with the introduction of Eu3+ in the BaWO4 lattice is the co-doping with Li+ / Eu3+. In this system two Ba2+ cations were replaced, resulting in different luminescent properties. Samples of BaWO4, Ba1- xEuxWO4, Ba1-3xEu2xWO4 and Ba1-2xEuxLixWO4 ( x = 1, 3 and 5 mol%) and BaWO4: Eu3+, Li+ (1:1, 3:3, 5:5 mol%) were thermally treated at 700, 900 and 1100 °C and characterized by X-ray diffraction (XRD), Raman scattering vibrational spectroscopy (RAMAN), infrared absorption vibrational spectroscopy of (FTIR), scanning electron microscopy (SEM), color index, UV-Vis diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL), X-ray excited optical luminescence (XEOL). All samples showed the same X-ray diffraction profile, independently of the dopants concentration (maximum of 10 at.%, Eu3+ + Li+) where it was observed the BaWO4 scheelite phase (JCPDS-PDF nº 43-646). The exceptions are the samples BaWO4:Eu3+,Li+ with 1,0:1,0 at.% and 3.0:3.0 at.%, treated at 700 and 900 °C, which presented low crystallinity. Greater crystallite size is achieved with smallest dopant concentration and highest thermal treatment temperature (700 to 1100 ºC). The study of the optical properties of Ba1-xEuxWO4, Ba1-3xEu2xWO4 e Ba1-2xEuxLixWO4 indicated that in... (Complete abstract click electronic access below)
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Vorpagel, Andreia Jaqueline. "Híbridos orgânicos-inorgânicos siloxanos àcidos-graxos emissores de luz branca /." Araraquara, 2012. http://hdl.handle.net/11449/97928.
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Orientador: Sidney José Lima RibeiroBanca: Elizabeth Stucchi
Banca: Elvio Antonio de Campos
Resumo: Novos compósitos híbridos orgânicos-inorgânicos foram preparados pela incorporação de nanopartículas de fórmula geral YVO4 dopada com os lantanídeos Yb/Er, Yb/Tm e Yb/Ho em matrizes híbridas do tipo "amidosil", obtidas da reação de ácido ricinoleico (AR) e 3-aminopropiltrietoxisilano (APTES). Os materiais foram caracterizados por espectroscopia de absorção no infravermelho, difração de raios X, microscopia eletrônica de transmissão e espectroscopia eletrônica. Estas partículas de vanadato de ítrio dopadas com lantanídeos, sob excitação no infravermelho (980 nm) emitem luz na região do visível em diferentes comprimentos de onda, devido a mecanismo de conversão ascendente de energia. A união nanopartículas e híbrido permitiu obter novos materiais híbridos emissores de luz branca, graças a um ajuste fino na relação matriz/partícula
Abstract: New composite organic-inorganic hybrid compounds were prepared by the incorporation of nanoparticles of general formula YVO4:Ln3+ (Ln= Yb/Er, Yb/Tm, Yb/Ho) in "amidosil" hybrids obtained from the reaction of ricinoleic acid (RA) and 3-aminopropyltriethoxysilane (APTES). The materials were characterized by infrared absorption spectroscopy, x-ray diffraction, scanning and transmission electron microscopy. Under infrared excitation (980 nm) vanadate nanoparticles emit visible light of different colors due to mechanism energy by up conversion energy transfer. The addition of variable relative contents of the nanoparticles into the hybrid host allowed different emission colors to be observed resulting the white
Mestre
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Romero, João Henrique Saska. "Efeito de compensação de cargas nas propriedades luminescentes dos materiais 'BA''WO IND.4':'EU POT.3+','LI POT.+' /." Araraquara, 2013. http://hdl.handle.net/11449/97930.
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Orientador: Marian Rosaly DavolosCoorientador: Marco Aurélio Cebim
Banca: Ieda Lúcia Viana Rosa
Banca: Rogéria Rocha Gonçalves
Resumo: As propriedades luminescentes, assim como a luminescência com excitação por raios X (XEOL) dos compostos Ba1-xEuxWO4, Ba1-3xEu2xWO4 e Ba1-2xEuxLixWO4 foram comparadas. As amostras foram obtidas pelo método Pechini com diferentes concentrações de dopante, diferentes atmosferas (mistura verde, argônio ou estática de ar) e temperaturas de tratamento térmico das amostras. BaWO4 forma compostos de estrutura tetragonal tipo Scheelita pertencentes ao grupo espacial I41/a. A substituição de íons Ba2+ por íons Eu3+ fornece dados importantes sobre a estrutura e a microssimetria do íon lantanídeo na matriz. Uma alternativa de compensação de carga com a introdução de Eu3+ no retículo do BaWO4 é a codopagem Li+/Eu3+. Neste sistema, dois cátions Ba2+ são substituídos, gerando a compensação de carga, resultando em propriedades luminescentes únicas. As amostras BaWO4, Ba1-xEuxWO4, Ba1-3xEu2xWO4 e Ba1-2xEuxLixWO4 (x = 1, 3 e 5% em mol) foram tratadas termicamente a 700, 900 e 1100º C e caracterizadas pelas técnicas de difração de raios X (XRD), espectroscopia de espalhamento Raman (RAMAN), espectroscopia vibracional de absorção na região do infravermelho (FTIR), microscopia eletrônica de varredura (SEM), índice de cor (CIE-Lab), espectroscopia de reflectância difusa (DRS), espectroscopia de fotoluminescência (PL), espectroscopia de luminescência com excitação por raios X (XEOL). As medidas XEOL foram realizadas no Instituto de Química Campus Araraquara. Todas as amostras apresentaram o mesmo perfil de difração, independentemente da concentração de dopante (máximo de 10%, Eu3+,Li+). A fase Scheelita (JCPDS-PDF nº 43-646) foi constatada. As exceções são as amostras BaWO4:Eu3+,Li+ dopadas com 1:1 e 3:3%, tratadas a 700 e 900 °C, que possuem baixa cristalinidade... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Luminescent properties, including X-ray excited optical luminescence (XEOL) of compounds Ba1-xEuxWO4, Ba1-3xEu2xWO4 and Ba1-2xEuxLixWO4 were compared. Samples were prepared by the Pechini method according to different dopand concentrations, different atmosphere (green mixture, argon and static air) and temperature during the thermal treatment of samples. Scheelite tetragonal structures of BaWO4 belongs to the space group I41/a. The Eu3+ substitutes for Ba2+ ions can provide important data on the structure and micro symmetry of lanthanide ions in the host lattice. An alternative way to charge compensation with the introduction of Eu3+ in the BaWO4 lattice is the co-doping with Li+ / Eu3+. In this system two Ba2+ cations were replaced, resulting in different luminescent properties. Samples of BaWO4, Ba1- xEuxWO4, Ba1-3xEu2xWO4 and Ba1-2xEuxLixWO4 ( x = 1, 3 and 5 mol%) and BaWO4: Eu3+, Li+ (1:1, 3:3, 5:5 mol%) were thermally treated at 700, 900 and 1100 °C and characterized by X-ray diffraction (XRD), Raman scattering vibrational spectroscopy (RAMAN), infrared absorption vibrational spectroscopy of (FTIR), scanning electron microscopy (SEM), color index, UV-Vis diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL), X-ray excited optical luminescence (XEOL). All samples showed the same X-ray diffraction profile, independently of the dopants concentration (maximum of 10 at.%, Eu3+ + Li+) where it was observed the BaWO4 scheelite phase (JCPDS-PDF nº 43-646). The exceptions are the samples BaWO4:Eu3+,Li+ with 1,0:1,0 at.% and 3.0:3.0 at.%, treated at 700 and 900 °C, which presented low crystallinity. Greater crystallite size is achieved with smallest dopant concentration and highest thermal treatment temperature (700 to 1100 ºC). The study of the optical properties of Ba1-xEuxWO4, Ba1-3xEu2xWO4 e Ba1-2xEuxLixWO4 indicated that in... (Complete abstract click electronic access below)
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Macario, Leilane Roberta. "Efeito das terras raras nas propriedades óticas do BaM'O.IND.3'(M==Zr, Ti) /." Araraquara : [s.n.], 2010. http://hdl.handle.net/11449/97886.
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Orientador: Elson Longo da SilvaBanca: Máximo Siu Li
Banca: Ieda Lucia Viana Rosa
Resumo: A necessidade de materiais com emissão luminescente tem aumentado continuamente com o desenvolvimento tecnológico. Para isto, torna-se necessária a obtenção de novos materiais, a fim de acompanhar esta crescente demanda. A criação de novos dispositivos depende, em geral, da obtenção de materiais que possam ser sintetizados, sem que haja a necessidade de utilização de condições especiais de síntese. Com isso, neste trabalho foram obtidas estruturas cristalinas de titanatos e zirconatos de bário dopados com a terra rara európio (Eu) por intermédio do método Hidrotérmico Assistido por Micro-ondas (HAM). Foram utilizadas as técnicas de caracterização, Difração de Raios X (DRX), Microscopia Eletrônica de Varredura (MEV), Espectroscopia Raman (FT-Raman), Espectroscopia de Reflectância no Ultravioleta e Visível (UV-Vis) e Fotoluminescência (FL), com intuito de verificar a influência do dopante Eu sobre as características ópticas e estruturais nos materiais. Assim, foi realizado um estudo correlacionando as técnicas de caracterização que permitiram uma avaliação das propriedades fotoluminescentes e da organização estrutural destes materiais. Os espectros de DRX mostraram que ambos os compostos podem ser obtidos, na fase cristalina a partir de um minuto de tratamento em HAM, sendo o zirconato de bário (BZ) de fase cúbica e o titanato de bário (BT) de fase tetragonal. A espectroscopia Raman foi uma ferramenta importante para caracterizar os compostos a curta distância de acordo com os tempos de síntese das amostras e da concentração de Eu. Por intermédio das medidas de UV-Vis verificou-se a presença de estados intermediários na região do "gap" gerados por defeitos estruturais nos compostos e a inserção dos íons Eu3+ nas redes cristalinas de BZ e BT. Os materiais sintetizados quando excitados em 350,7 nm apresentaram emissões de banda larga na região...(Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The need for materials with luminescence increases with technological development, which grows every day. For this, it becomes necessary the obtention of new materials in order to follow this growing demand. The creation of new devices depends, in general, from obtaining materials that can be synthesized without the need to use special conditions of synthesis. Thus, in this work crystal structures of barium titanate and barium zirconate doped with rare earth europium (Eu) were obtained through the hydrothermal method assisted by microwave (HAM). The characterization techniques used were X-Ray Diffraction (XRD), Scanning Electron Microscopy (EMS), Raman Spectroscopy (FT-Raman), Reflectance Spectroscopy on Ultraviolet and Visible (UV-Vis) and Photoluminescence (FL), in order to verify the influence of doping on the synthesized materials. Thus, a study correlating the characterization techniques that have allowed an evaluation of the photoluminescent properties and structural organization of these materials was necessary. XRD spectra showed that both materials can be obtained in crystalline phase from one minute of treatment on HAM, giving barium zirconate (BZ) in cubic phase and barium titanate (BT) in tetragonal phase. Raman spectroscopy has been an important tool to characterize the compounds in short distance according to the time of synthesis and Eu concentrations. By means of UV-Vis measurements the presence of intermediate states were observed in the region of gap generated by structural defects in the compounds and the insertion of Eu3+ ions in the crystalline lattice of BZ and BT. The synthesized materials, when excited at 350.7 nm, showed a broadband emission in the visible region, with a variation of intensity of broad bands relative to the luminescence of the matrices by varying the concentration of Eu3+, as well as intensity variations on emissions from the rare earth in question... (Complete abstract click electronic access below)
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Oliveira, Higor Henrique de Souza [UNESP]. "Propriedades e mecanismos de cintilação dos materiais 'GD''AL''O IND.3' e ('GD''LU')'AL''O IND.3' dopados com 'EU POT. 3+', 'TB POT. 3+' e 'PR POT. 3+'." Universidade Estadual Paulista (UNESP), 2011. http://hdl.handle.net/11449/97926.
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Cintiladores são materiais capazes de absorver radiações de alta energia e convertê-las eficientemente em radiações ultravioleta ou visível. Avanços significativos na eletrônica de detecção dessas radiações motivaram as pesquisas visando à busca por novos materiais cintiladores de alta eficiência e à maior compreensão do mecanismo de cintilação. Nesse contexto, os compostos de matriz GdAlO3 e Gd1-xLuxAlO3 dopados com Eu3+, Tb3+ ou Pr3+ são materiais cintiladores promissores, pois apresentam alta densidade, elevados valores de coeficiente de atenuação de massa e propriedades espectroscópicas relevantes como emissão intensa, tempo de vida de mili ou microssegundos e transferência de energia a partir dos íons Gd3+ para os ativadores. Neste trabalho, foi investigada a preparação dos cintiladores GdAlO3 e Gd1-xLuxAlO3 nominalmente puros e dopados com Eu3+, Tb3+ e Pr3+ através do método dos precursores poliméricos (método Pechini) e suas propriedades estruturais e espectroscópicas (fotoluminescência e luminescência com excitação por raios X) foram investigadas. O perfil espectral de emissão das amostras de GdAlO3 dopadas com Eu3+ evidencia a ocupação de dois sítios distintos pelos íons dopantes quando em concentrações superiores a 1,0%-mol, provavelmente devido à distribuição não homogênea dos íons na matriz. A transferência de energia Gd3+→Ln3+ foi evidenciada pela espectroscopia de fotoluminescência e é um processo importante no mecanismo de cintilação desses materiais, como evidenciado pela comparação das medidas espectroscópicas de fotoluminescência e luminescência com excitação por raios X das amostras de GdAlO3:Pr3+. Com a incorporação de Lu3+ na matriz de GdAlO3, a intensidade de emissão aumenta até a concentração de 10%-mol de Lu3+, decrescendo...
Scintillators materials are compounds that can absorb ionizing radiations and efficiently convert them into UV-VIS radiations. Despite of impressive advances in the technology of direct detection, the search for new scintillators materials with high efficiency and for the precise understanding of the scintillation mechanism is still the focus of research in this area. In this context, the compounds GdAlO3 and Gd1-xLuxAlO3 doped with Eu3+, Tb3+ and Pr3+ are promising scintillators materials, since they have high density, high values of mass attenuation coefficient and relevant spectroscopic properties, such as bright emission, lifetime of milli or microseconds and the energy transfer from Gd3+ ions to the activators. This work describes the preparation of GdAlO3 and Gd1-xLuxAlO3 nominally pure and doped with Eu3+, Tb3+ e Pr3+ by the polymeric precursor method (Pechini method) and the study of their structural and spectroscopic (photoluminescence and X-rays excited optical luminescence) properties. Emission spectral profile of Eu3+-doped GdAlO3 indicates the occupation of two different sites by the dopant ions when the concentration is higher than 1.0 mol-%, probably due to inhomogeneous distribution of ions in the host. The energy transfer Gd3+→Ln3+ was evidenced by photoluminescence spectroscopy and is an important process in the scintillation mechanism of these materials, as showed by comparison of spectroscopic measurements of photoluminescence and X-rays excited optical luminescence of GdAlO3:Pr3+ sample. The emission intensity increases by incorporating Lu3+ in the GdAlO3 host until the Lu3+ concentration of 10 mol-%, decreasing at higher concentrations. This behavior is probably assigned to the balance between increasing the absorption of X-rays and the reduction of the transfer process from Gd3+ ions with increasing concentration of... (Complete abstract click electronic access below)
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Ledoux, Gilles. "Luminescence dans les nano-objets." Habilitation à diriger des recherches, Université Claude Bernard - Lyon I, 2008. http://tel.archives-ouvertes.fr/tel-00442674.
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Les matériaux lorsqu'ils sont rendus nanométriques montrent des propriétés optiques qui peuvent différer fortement des celles des matériaux à l'état massif. C'est l'étude de ces modifications des propriétés qui a motivé les travaux qui sont présentés dans ce document. Dans une première partie je décris les propriétés de luminescence particulière des nanocristaux de silicium en mettant en évidence un décalage de la luminescence vers le bleu lorsque la taille des nanocristaux diminue et je montre qu'il s'agit d'un phénomène de confinement quantique. Dans le même temps l'importance de la passivation de surface est démontrée. Ces résultats sont ensuite appliqués à la compréhension d'une signature spectrale détectée dans les nuages de poussières inter- et circumstellaires et la fabrication de microcavités luminescente à base de nanocristaux de silicium. Dans une deuxième partie je présente les résultats des études que je mène depuis mon arrivée au sein du LPCML sur les propriétés de luminescence de nanoparticules d'oxydes dopés terres rares. Nous avons ainsi pu montrer que le confinement quantique peut aussi être mis en évidence pour ces matériaux fortement ionique même si l'effet est bien moindre que pour les semi conducteurs. De même on montre que la surface joue un rôle essentiel soit en donnant lieu à de nouvelles émissions soit en créant des défauts tueurs de la luminescence. La taille des nanoparticules modifie aussi la densité d'états de phonons ce qui modifie les populations dans les différents niveaux d'énergie des ions dopants et donc les rapports d'intensité entre les transitions optiques. Enfin le comportement sous excitation à haute énergie (UV dur et X) montre que les rendements sont fortement affectés pour les petites tailles traduisant l‘impossibilité pour les toutes petites particules de supporter une trop grande densité d'excitation. La dernière partie présente les deux axes que je souhaite développer dans les années à venir à savoir la microscopie confocale jusque dans l'UV dur et l'ablation laser en solution pour la synthèse de nanomatériaux originaux.
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Miller, Paul Francis. "Luminescence studies of molecular materials." Thesis, Imperial College London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342250.
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Gautier, Annaig. "Luminescence dating of archaeometallurgical slag." Thesis, University of Oxford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326805.
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Lai, ZhongPing. "Luminescence dating of Chinese loess." Thesis, University of Oxford, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.419053.
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Scotland, W. R. "Luminescence techniques in environmental analysis." Thesis, Heriot-Watt University, 1990. http://hdl.handle.net/10399/877.
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Alexeev, Evgeny. "Hot-carrier luminescence in graphene." Thesis, University of Exeter, 2015. http://hdl.handle.net/10871/18231.
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In this thesis, the effect of the sample properties on the characteristics of the hot carrier luminescence in graphene is investigated. The present work focuses on the two main issues described below. The first issue is the modification effects of near-infrared pulsed laser excitation on graphene. For excitation fluences several orders of magnitude lower than the optical damage threshold, the interaction with ultrafast laser pulses is found to cause a stable change in the properties of graphene. This photomodification also results in a decrease of the hot photoluminescence intensity. The detailed analysis shows that ultrafast photoexcitation leads to an increase in the local level of hole doping, as well as a change in the mechanical strain. The variation of doping and strain are linked with the enhanced adsorption of atmospheric oxygen caused by the distortion of the graphene surface. These findings demonstrate that ultrashort pulsed excitation can be invasive even if a relatively low laser power is used. Secondly, the variation of the hot photoluminescence intensity with the increasing charge carrier density in graphene is investigated. The electro-optical measurements performed using graphene field-effect transistors show a strong dependence of the photoluminescence intensity on the intrinsic carrier concentration. The emission intensity has a maximum value in undoped graphene and decreases with the increasing doping level. The theoretical calculations performed using a refined two-temperature model suggest that the reduction of the photoluminescence intensity is caused by an increase in the hot carrier relaxation rate. The modification of the carrier relaxation dynamics caused by photoinduced doping is probed directly using the two-pulse correlation measurements. The discovered sensitivity of the hot photoluminescence to the intrinsic carrier concentration can be utilised for spatially-resolved measurements of the Fermi level position in graphene samples, offering an advantage in resolution and speed.
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Trice, Brian Edward. "Nonlinear Luminescence Quenching in Eu2O3." Thesis, Virginia Tech, 2000. http://hdl.handle.net/10919/30960.
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Nonlinear luminescence quenching has been documented in numerous systems such as organic crystals, rare earth insulators, laser materials, semiconductors, and phosphors. In each of these systems nonlinear luminescence quenching occurs under conditions of high excitation density from interactions between excited centers, the result is an additional nonradiative decay pathway that lowers luminescence quantum efficiency.
During investigations into the spectra and dynamics of Eu2O3, an apparent saturation dip in the excitation spectra of nano-sized Eu2O3 particles was observed. This thesis describes the investigation into the nature of the saturation effect. The samples studied using luminescent spectroscopy included micron sized Eu2O3 crystals of both cubic and monoclinic phases, nanocrystal monoclinic Eu2O3, and a large fused crystal of monoclinic Eu2O3. It was determined that the saturation effect was due to nonlinear luminescence quenching occurring at the wavelengths of absorption maxima. The mechanism of nonlinear luminescence quenching was concluded to be upconversion by energy transfer.Master of Science
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Zhao, Lai. "Integrated ballistic electron emission luminescence." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 71 p, 2008. http://proquest.umi.com/pqdweb?did=1605147361&sid=3&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Saliba, Lucas Falquetti [UNESP]. "Interação do complexo luminescente [Eu(tta)3] com sílica mesoporosa." Universidade Estadual Paulista (UNESP), 2009. http://hdl.handle.net/11449/91994.
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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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Petruci, Foão Flávio da Silveira [UNESP]. "Sensores ópticos para quantificação de sulfeto de hidrogênio em matrizes gasosas por espectrometria de floorescênica do UV-visível e espectroscopia de absorção no infravermelho: João Flávio da Silveira Petruci. -." Universidade Estadual Paulista (UNESP), 2014. http://hdl.handle.net/11449/110852.
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000781231.pdf: 1372057 bytes, checksum: e6fbde2a479b8ad06bf6fbb599cf0a45 (MD5)Dentre os poluentes gasosos, o sulfeto de hidrogênio (H2S) e seus derivados - conhecidos como Compostos Reduzidos de Enxofre (CRE) - possuem grande destaque devido a sua alta toxicidade, propriedade corrosiva e participação em problemas ambientais diversos. Diferentes órgãos de controle de emissão ao redor do mundo estabelecem limites para a presença de H2S em diversos ambientes, variando de ppm (μg g-1) até baixo ppb (ng g-1). Para que estes limites sejam de fato cumpridos, é necessário que existam métodos analíticos que produzam resultados confiáveis para quantificar e, consequentemente, monitorar H2S em ambiente gasoso. Sensores ópticos apresentam vantagens como custo acessível, facilidade de operação, potencialidade para miniaturização e facilidade de aplicação em campo. Diversos compostos químicos com propriedades luminescentes tem sido utilizados como reagente para detecção de H2S, entretanto, a maioria é baseado em metais tóxicos (p.e. mercúrio), além de síntese complexa envolvendo várias etapas. Dentro desse contexto, a primeira parte desse trabalho envolve a síntese e caracterização de um composto inédito de paládio denominado bis (2-aminobenzóico) paládio (II), que possui comprimento de onda máximo de emissão em 410 nm quando excitado em 245 nm. Esse composto reage rapidamente com sulfetos aquosos e gasosos, liberando para o meio o ligante ácido 2-aminobenzóico, responsável pelo aumento da intensidade de fluorescência, proporcional a quantidade de sulfeto. O método desenvolvido possui limite de detecção de 0,075 μmol L-1 e 6,8 ppbv para sulfeto e H2S, respectivamente. A segunda etapa do trabalho envolveu a utilização da espectroscopia de absorção no infravermelho acoplada a uma nova geração de células gasosas, denominadas substrate-integrated hollow waveguides (i-HWG), para determinação em tempo real de H2S em matrizes gasosas. A determinação envolve a conversão imediata...
Among the gaseous pollutants, hydrogen sulfide and its derivatives – also know as Reduced Sulfur Compounds (RSC) – have been attracting attention due their high toxicity, corrosive proprieties and involvement in several environmental issues. For this reason, there are many agencies worldwide that establish limits for the presence of H2S and RSC in several environmental compartments ranging from ppm (μg g-1) to low ppb (ng g-1). In order to enable the monitoring of these compounds in air, analytical methods must provide reliable and accurate results. Optical sensors appear particularly advantageous in terms of equipment cost, simplicity, easiness of operation, and potential for miniaturization. Several chemical compounds with luminescent proprieties have been used as reagent for sulfide detection. However, most of them are based on toxic metals and, furthermore, their synthesis contains many steps and generates toxic residues. In light of this context, a new palladium chelate compound – denominate bis (2-aminobenzoic) palladium (II) – was used to determinate sulfides in aqueous and gaseous samples as described in the first part of this thesis. The compound reacts with sulfides leading to the increase of the fluorescence intensity at 410 nm, when excited at 245 nm. The method was validated and enabled the determination of 0.075 μmol L- 1 and 6.8 ppbv for aqueous sulfide and gaseous H2S, respectively. The second part of this thesis involves the use of infrared spectroscopy coupled to a new generation of hollow waveguides, so-called substrate-integrated hollow waveguides, for the real-time monitoring of H2S in gaseous samples. The determination is based on the instantly and UV-based conversion of H2S to SO2, a very strong IR absorber at 1245 cm-1. The method enables the determination of 3 ppm of H2S.
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Petruci, Foão Flávio da Silveira. "Sensores ópticos para quantificação de sulfeto de hidrogênio em matrizes gasosas por espectrometria de floorescênica do UV-visível e espectroscopia de absorção no infravermelho / João Flávio da Silveira Petruci. -." Araraquara, 2014. http://hdl.handle.net/11449/110852.
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Orientador: Arnaldo Alves CardosoBanca: José Anchieta Gomes Neto
Banca: Pedro Paulo Corbi
Banca: Ricardo Queiroz Aucélio
Banca: Mauro Korn
Resumo: Dentre os poluentes gasosos, o sulfeto de hidrogênio (H2S) e seus derivados - conhecidos como Compostos Reduzidos de Enxofre (CRE) - possuem grande destaque devido a sua alta toxicidade, propriedade corrosiva e participação em problemas ambientais diversos. Diferentes órgãos de controle de emissão ao redor do mundo estabelecem limites para a presença de H2S em diversos ambientes, variando de ppm (μg g-1) até baixo ppb (ng g-1). Para que estes limites sejam de fato cumpridos, é necessário que existam métodos analíticos que produzam resultados confiáveis para quantificar e, consequentemente, monitorar H2S em ambiente gasoso. Sensores ópticos apresentam vantagens como custo acessível, facilidade de operação, potencialidade para miniaturização e facilidade de aplicação em campo. Diversos compostos químicos com propriedades luminescentes tem sido utilizados como reagente para detecção de H2S, entretanto, a maioria é baseado em metais tóxicos (p.e. mercúrio), além de síntese complexa envolvendo várias etapas. Dentro desse contexto, a primeira parte desse trabalho envolve a síntese e caracterização de um composto inédito de paládio denominado bis (2-aminobenzóico) paládio (II), que possui comprimento de onda máximo de emissão em 410 nm quando excitado em 245 nm. Esse composto reage rapidamente com sulfetos aquosos e gasosos, liberando para o meio o ligante ácido 2-aminobenzóico, responsável pelo aumento da intensidade de fluorescência, proporcional a quantidade de sulfeto. O método desenvolvido possui limite de detecção de 0,075 μmol L-1 e 6,8 ppbv para sulfeto e H2S, respectivamente. A segunda etapa do trabalho envolveu a utilização da espectroscopia de absorção no infravermelho acoplada a uma nova geração de células gasosas, denominadas substrate-integrated hollow waveguides (i-HWG), para determinação em tempo real de H2S em matrizes gasosas. A determinação envolve a conversão imediata...
Abstract:Among the gaseous pollutants, hydrogen sulfide and its derivatives - also know as Reduced Sulfur Compounds (RSC) - have been attracting attention due their high toxicity, corrosive proprieties and involvement in several environmental issues. For this reason, there are many agencies worldwide that establish limits for the presence of H2S and RSC in several environmental compartments ranging from ppm (μg g-1) to low ppb (ng g-1). In order to enable the monitoring of these compounds in air, analytical methods must provide reliable and accurate results. Optical sensors appear particularly advantageous in terms of equipment cost, simplicity, easiness of operation, and potential for miniaturization. Several chemical compounds with luminescent proprieties have been used as reagent for sulfide detection. However, most of them are based on toxic metals and, furthermore, their synthesis contains many steps and generates toxic residues. In light of this context, a new palladium chelate compound - denominate bis (2-aminobenzoic) palladium (II) - was used to determinate sulfides in aqueous and gaseous samples as described in the first part of this thesis. The compound reacts with sulfides leading to the increase of the fluorescence intensity at 410 nm, when excited at 245 nm. The method was validated and enabled the determination of 0.075 μmol L- 1 and 6.8 ppbv for aqueous sulfide and gaseous H2S, respectively. The second part of this thesis involves the use of infrared spectroscopy coupled to a new generation of hollow waveguides, so-called substrate-integrated hollow waveguides, for the real-time monitoring of H2S in gaseous samples. The determination is based on the instantly and UV-based conversion of H2S to SO2, a very strong IR absorber at 1245 cm-1. The method enables the determination of 3 ppm of H2S.
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Impellizzeri, Stefania. "Engineering of Nanoparticles for Luminescence Switching." Scholarly Repository, 2012. http://scholarlyrepository.miami.edu/oa_dissertations/708.
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Fluorescence microscopy offers the opportunity to image biological samples noninvasively in real time and has become an essential analytical tool in the biomedical laboratory. Nonetheless, the phenomenon of diffraction imposes stringent limitations on the resolving power of conventional microscopes, preventing the spatial resolution of fluorescent species co-localized within areas of nanoscaled dimensions. Time, however, can be exploited to distinguish fluorophores within the same subdiffraction area, if their fluorescence can be switched independently, and reconstruct sequentially their spatial distribution. In this context, photolytic reactions and photochromic transformations can be invoked to switch fluorescence under optical control. Fluorescent units, such as inorganic semiconductor nanoparticles and organic dyes, and photoactive components can be operated within a common supramolecular matrix or integrated within the same molecular construct to produce photoswitchable fluorescent assemblies. In the resulting systems, electronic communication between the components can be designed in order to photoactivate or photodeactivate fluorescence respectively. Both mechanisms can be exploited to overcome diffraction, and ultimately permit the reconstruction of images with resolution down to the nanometer level, in combination with appropriate illumination protocols.
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Dai, Lixiong. "Structural modifications to optimise lanthanide luminescence." HKBU Institutional Repository, 2017. http://repository.hkbu.edu.hk/etd_oa/403.
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Luminescent lanthanide coordination complexes have attracted significant attention due to their unique optical properties. The poor absorption of a lanthanide ion can be resolved by so-called antenna effect and improve the intensity of its luminescence. Three bidentate chromophores: phosphate-pyridine chromophore, 1,2-Hydroxy pyridone (1,2-HOPO) and 2-thenoyltrifluoroacetone (TTA), functioned as both chelator and sensitizer, their energy levels are well matched with the excited state energy levels of the Eu(III) and Sm(III).. To get highly luminescent and stable lanthanide complex, we designed and synthesized various Eu(III) complexes with different backbones to compare different parameters that will affect the sensitizing efficiency of the chromophores, such as rigidity, geometry and coordination saturation.. In chapter two we combined the phosphate-pyridine chromophore with the well-studied cyclen-based chelator to fulfil the requirement of high stability and brightness. We designed a nine-coordinate europium(III) complex as platform, through coupling reactions to realise fast screen of the chromophores energy transfer efficiency.. Chapter three focuses on the structure modifications based on the chromophore of 1,2-HOPO, different chelators and backbones were compared, a europium complex EuL4 with the highest quantum yield with this chromophore was obtained and it could goes into cells and localized on lysosome very fast. Two-phonon in vitro imaging was done which showed its high potential bioapplications.. Chapter four focuses on the structure modification based on the chromophore of TTA. Different backbone directly determined the europium complexes saturation number and sensitization efficiency, therefore, their quantum yields.
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Adamson, Philip George. "Luminescence studies of water-soluble polymers." Thesis, Lancaster University, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.428737.
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Huntriss, Alicia. "A Bayesian analysis of luminescence dating." Thesis, Durham University, 2008. http://etheses.dur.ac.uk/2928/.
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Luminescence dating is a widespread dating method used in the fields of archaeology and Quaternary science. As an experimental method it is subject to various uncertainties in the determination of parameters that are used to evaluate age. The need to express these uncertainties fully, combined with the prior archaeological knowledge commonly available, motivates the development of a Bayesian approach to the assessment of age based on luminescence data. The luminescence dating procedure is dissected into its component parts, and each is considered individually before being combined to find the posterior age distribution. We use Bayesian multi-sample calibration to find the palaeodose in the first stage of the model, consider the problem of identifying a plateau in the data, and then use this, along with the annual dose, to estimate age. The true sample age is then modelled, incorporating any prior information available, both for an individual sample and for a collection of samples with related ages.
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Bradshaw, Rebecca. "Luminescence from actinides and actinyl ions." Thesis, University of Oxford, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.526580.
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Brooks, Robert. "Ion beam induced luminescence of materials." Thesis, University of Sussex, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.391861.
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Belharouak, Ilias. "Luminescence de l'argent dans les phosphates." Phd thesis, Université Sciences et Technologies - Bordeaux I, 1999. http://tel.archives-ouvertes.fr/tel-00972640.
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Le but de ce travail était d'étudier et de caractériser la luminescence de l'argent dans les matériaux phosphatés, qu'ils soient cristallisés ou vitreux. Trois types de centres photoluminescents ont été mis en évidence : le premier centre, appelé (A) est caractéristique des transitions dans les phases AgM(PO3)3 (M = Mg, Zn, Ba) et Na2-xAgxZnP2O7 dont les structures ont été complètement déterminées. La dynamique de son émission peut être expliquée dans la plupart des cas par un système à trois niveaux. Le centre (C) est attribué à des "paires" d'argent. En effet, lorsque les structures cristallines le permettent, des interactions indirectes Ag+--Ag+ peuvent se développer entre deux cations voisins, chacun occupant son propre site cristallochimique. Un type particulier d'interaction d10--d10 a pu être rencontré, il s'agit des associations Ag+--Zn2+ dont l'existence est suggérée pour expliquer la présence de l'émission (C) détectée dans le polyphosphate AgZn(PO3)3. La fluorescence (B) est détectée à la périphérie des agrégats micrométriques d'argent métallique dans les verres phosphosilicate du système "P2O5-SiO2-ZnO-Ag2O". Ses caractéristiques spécifiques ont permis de l'associer à un type d'interaction différent, en l'occurence à des interactions Ag0--Ag+.
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Johnson, George Anthony. "Luminescence studies of latent fingerprint residue." Thesis, University of East Anglia, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.257556.
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Williams, James Anthony Gareth. "Luminescence behaviour of macrocycle metal complexes." Thesis, Durham University, 1995. http://etheses.dur.ac.uk/5313/.
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Luminescent complexes of lanthanide ions are of growing interest because the long lifetime of emission allows time-resolved detection procedures to be employed. A key step in the development of such systems lies in the preparation of highly luminescent complexes which display high stability in aqueous solution. A series of ligands based on 1,4,7,10-tetraazacyclododecane have been prepared, in which the nitrogen atoms are appended with coordinating phosphinate or amide groups, or a combination of both. The compounds obtained are octadentate ligands which form water-soluble lanthanide complexes of high stability. Complexes incorporating aryl groups in the pendent arms have been prepared and some display intense metal luminescence following excitation into the organic chromophores. A back energy transfer process occurs in the terbium complexes containing naphthyl or quinohnone groups. Measurements of the luminescence lifetimes in H(_2)O and H(_2)O show diat diere are no metal-bound water molecules in the tetrabenzylphosphinate complexes. Those incorporating one amide and three phosphinate groups display hydration states between 0 and 1. An attempt has been made to correlate this information with that obtained from an analysis of the nuclear magnetic resonance dispersion profiles of related gadolinium complexes. The complexes incorporating secondary amide groups display an additional deactivation pathway for the metal excited state involving energy transfer into N-H bonds. The luminescence behaviour of four macrocyclic tetraamide ligands incorporating naphthyl fluorophores has been studied. These compounds exhibit distinctive changes in luminescence in the presence of quenching (eg. Pb(^2+), Cu(^2+) and Ni(^2+)) and non- quenching ions (eg. Cd(^2+) and Zn(^2+)). This behaviour extends to non-aqueous solution. The protonated tetranaphthyl ligand forms an intramolecular excimer in which the excimer emission displays a sensitive dependence on the polarity of die solvent.
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Manson-Smith, Sacha Kinsey. "Investigation into scanning tunnelling luminescence microscopy." Thesis, University of Strathclyde, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366826.
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Li, Hongguang. "Responsive luminescence toolbox for biological applications." HKBU Institutional Repository, 2016. https://repository.hkbu.edu.hk/etd_oa/275.
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In chapter one, literature review have been down about the photophysical properties of lanthanide complexes and their applications. In chapter 2, the design and synthesis of water soluble cyclen based europium complexes with cyclin A specific peptides were described. Linear and two-photon induced hypersensitive europium emission gave the real time signalling and also enhanced the two-photon induced emission from 12GM to 68GM after Cyclin A binding. In chapter 3, the design of water soluble multi-modal porphyrin based compounds for key cell cycle regulator- Plk 1 imaging and cancer cells inhibition were described. Two water soluble porphyrin compounds have been synthesized and shown the specific photodynamic therapy treatment in the cancer cells via the selectively binding with Polo-like kinase 1 (Plk1). Plk1 is responsible for cell cycle regulation. Commercial or known Plk1 inhibitor/bioprobes are always poor cell internalization and easily to be damaged by enzymatic degradation. In addition, these markers are not available to image and inhibit the Plk1 as dual function probe. We introduced a new approach amphiphilic porphyrin with Plk1 specific peptide. Our compounds shown responsive emission enhancement upon binding with Plk1 in aqueous medium. In vitro, it can triggered G2-M phase arrest and inhibited the cancer cells specific as Plk1 is overexpressed in cancer cell. In chapter 4, we designed and synthesized a platinumeuropium complex (PtEuL401) as a controlled delivery vehicle of cisplatin. PtEuL401 shown responsive emission with the appropriate light excitation in aqueous and in vivo during the drug delivery process. Compared with the existing prodrugs, we offer real-time monitoring of the therapy process. Also, the long emission lifetimes of lanthanides creates room for further development in time-resolved imaging protocols which eliminates the problem of autofluorescence.
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Wheeler, G. C. W. S. "Luminescence studies relevant to archaeological dating." Thesis, University of Oxford, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.670305.
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Balabhadra, Sangeetha. "Ln3+-doped nanoparticles for luminescence thermometry." Doctoral thesis, Universidade de Aveiro, 2017. http://hdl.handle.net/10773/23491.
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Doutoramento em FísicaA temperatura é uma variável chave que afeta a maior parte dos sistemas, quer naturais quer construídos pelo Homem. A medida da temperatura é global, uma vez que regula a cinética e a reatividade daqueles sistemas, ao nível atómico e macroscópico. Os sensores convencionais são ineficientes para a medição remota da temperatura à micro e à nanoescala o que, nos últimos anos, tem inspirado o desenvolvimento de nanotermómetros não-invasivos, sem contato, autorreferenciados e exibindo alta sensibilidade térmica. Neste contexto, a utilização de iões lantanídeos trivalentes (Ln3+), devido às suas propriedades fotoluminescentes que dependem fortemente da temperatura, tem sido uma das aproximações mais promissoras. Esta tese discuta as propriedades de nanopartículas dopadas com iões Ln3+ emitindo na gama espectral do visível e infravermelho-próximo como sensores de temperatura molecular. Na primeira parte da tese, estudaram-se nanopartículas de Gd2O3 dopadas com Nd3+ operando na gama espectral do infravermelho-próximo como nanotermómetros luminescentes baseados num rácio de intensidades. A emissão de nanotubos e nanobastonetes de Gd2O3:Nd3+ foi medida usando um tubo fotomultiplicador R928 comum na primeira janela biológica (800920 nm) tendo-se obtido na faixa fisiológica (288323 K), respetivamente, uma sensibilidade térmica e uma incerteza em temperatura de 1.75±0.04 %K-1 e 0.14±0.05 K. A dependência com a temperatura da emissão de nanoesferas de Gd2O3:Nd3+ na segunda janela biológica (12501550 nm), com excitação a 808 nm na primeira janela biológica, foi, também, estudada mostrando uma sensibilidade térmica máxima de 0.237±0.03 %K-1 a 303 K. Na segunda parte da tese foram desenvolvidas nanopartículas conversoras ascendentes de energia de Gd2O3 e SrF2 dopadas com Yb3+/Er3+ para termometria, tendo como parâmetro termométrico a intensidade integrada das transições 2H11/24I15/2/4S3/24I15/2 do ião Er3+. Desenvolveram-se nanoplataformas combinando nanotermómetros de Gd2O3:Yb3+/Er3+ com nanopartículas de Ouro (nanoaquecedores) para medir a temperatura induzida pelo plasmão das partículas metálicas. A condição ótima para um aquecimento térmico efetivo foi conseguida ajustando a banda de ressonância de superfície localizada do plasmão (LSPR) na gama fisiológica (302330 K). Quando comparadas com as nanopartículas de Gd2O3:Yb3+/Er3+, as nanopartículas de SrF2:Yb3+/Er3+ apresentam uma eficiência de emissão da conversão ascendente de energia e uma dispersibilidade superiores tendo sido estudada a dependência com a temperatura das suas propriedades de emissão, tanto em forma de suspensão como em pó. Além disso, realizaram-se medições do fluxo espectral e do rendimento quântico absoluto de emissão usando um espectrômetro com uma esfera de integração e um medidor de potência. Foi, também, proposto um método inovador para prever a curva de calibração da intensidade de emissão versus temperatura de qualquer termómetro luminescente baseado em dois níveis eletrónicos termicamente acoplados, utilizando como exemplo nanopartículas de SrF2:Yb3+/Er3+.
Temperature is a master variable that affects essentially most of the natural and engineered systems. The measurement of temperature is a virtually ubiquitous requirement as it governs the kinetics and reactivity of these systems from their atomic to macroscopic level. The conventional temperature sensors, proved to be ineffective for remote temperature measurement at the micro and nanoscale. This has been strongly stimulated for the development of non-invasive, noncontact and self-referencing nanothermometers exhibiting high thermal sensitivity. In this context one of the most promising approaches proposes the use of trivalent lanthanide ions (Ln3+) that present photoluminescent properties that are temperature dependent. This thesis reports Ln3+-doped visible emitting upconverting and near-infrared emitting downshifting nanoparticles as molecular temperature sensors. Primarily, Nd3+-doped near-infrared exciting and near-infrared emitting downshifting Gd2O3 nanoparticles as an intensity-based ratiometric nanothermometer were evaluated. The performance of Gd2O3:Nd3+ nanorods were enquired using a common R928 photomultiplier tube in the first transparent biological window (800–920 nm). The highest thermal sensitivity and temperature uncertainty (1.75±0.04 %K−1 and 0.14±0.05 K, respectively) were reported for Gd2O3:Nd3+ nanorods in the physiological range (288–323 K). Similarly, the performance of Gd2O3:Nd3+ nanospheres were briefly investigated for their temperature dependent emission in the second biological window (12501550 nm) upon excitation in the first biological window (at 808 nm). The Gd2O3:Nd3+ nanospheres exhibit a maximum thermal sensitivity of 0.237±0.03 %K-1 at 303 K were obtained. Secondarily, Yb3+/Er3+-doped near-infrared exciting and visible emitting upconverting Gd2O3 and SrF2 nanoparticles were developed for thermometry based on the thermometric parameter, as the integrated intensity of 2H11/2→4I15/2/4S3/2→4I15/2 Er3+ transitions. Gd2O3 nanorods as thermometers combined with Au as heater nanoplatforms were constructed, to measure plasmon-induced temperature increase of Au nanorods. The optimal condition for the effective thermal heating was achieved by tuning the localized surface plasmon resonance band in the physiological range (302–330 K). In order to increase upconversion emission efficiency and the dispersibility, further SrF2 nanoparticles were explored and the thermal sensing properties were exploited both in powder and water suspension forms. Moreover, the measurements of spectral flux and the absolute quantum yield were accomplished followed a method using an integrating sphere-based spectrometer and a power meter. Considered a furtherance step is to demonstrate a straightforward method to predict the temperature calibration curve of any upconverting thermometer based on two thermally-coupled electronic levels independently of the medium, taking SrF2 nanoparticles as an illustrative example.
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Fan, Xiao. "Heterometallic coordination polymers : toward luminescence modulation." Thesis, Rennes, INSA, 2015. http://www.theses.fr/2015ISAR0007/document.
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Les polymères de coordination décrits dans cette thèse ont été préparés en accord avec les concepts de la chimie verte par réactions dans l’eau entre les sels de sodium des ligands et les ions lanthanides compris entre La et Lu (sauf Pm) plus Y. Deux types d’échantillons ont été préparés : des monocristaux et des poudres microcristallines. Les structures cristallines ont été résolues sur la base des monocristaux et les poudres microcristallines ont été utilisées pour étudier les propriétés physicochimiques des composés : stabilité thermique, propriétés de luminescence et de magnétisme. Dans nos travaux, quatre systèmes de polymères de coordination ont été étudiés. Ils ont été obtenus à partir de quatre acides : acide chelidonique (H2cda), acide 5-hydroxy-isophthalique (H2hip), acide 5-nitroisophthalique (H2nip) et acide 4-carboxyphenylboronique (Hcpb). Dix nouveaux monocristaux ont été obtenus par diffusions lentes en tubes en U à travers des gels physique (Agar) ou chimiques (TMOS ou TEOS), par diffusion lente en tubes en H à travers de l’eau distillée ou par évaporation lente du filtrat obtenu après la synthèse des poudres microcristallines. Les poudres microcristallines ont été classées sur la base de leurs diagrammes de diffraction des rayons-X. Leurs propriétés de luminescence ou de magnétisme ont été étudiées à l’état solide. Les transferts d’énergie intermétalliques ont été discutés, en particulier pour les ligands H2hip et Hcpb. Les composés hétéro-nucléaires (Gd / Tb et Eu / Tb) ont été préparés pour moduler les propriétés luminescentes de ces composés en variant les proportions relatives en ions lanthanides. Les polymères de coordination à base de terres rares synthétisés et étudiés dans ce manuscrit fournissent des informations intéressantes pour la conception future de matériaux multifonctionnelsAccording to the concepts of Green Chemistry, the coordination polymers based on lanthanide ions were prepared by reactions in water between the sodium salts of ligands and lanthanide ions comprised between La and Lu (except Pm) plus Y. Two kinds of samples were prepared : single crystals and microcrystalline powders. The former ones are used to determine the single crystal structure, and the later ones are used to measure the physical-chemical properties : thermal stability, luminescence and magnetism properties. In our work, four ligands were explored: chelidonic acid (H2cda), 5-hydroxy-isophthalic acid (H2hip), 5-nitroisophthalic acid (H2nip) and 4-carboxyphenylboronic acid (Hcpb). As a result, 10 new single crystals were obtained by slow diffusion in U-shape tubes through physical gel (agar) or chemical gels (TMOS or TEOS), by slow diffusion in H-shape tubes through distilled water or by evaporation of the filtrate obtained after the synthesis of the microcrystalline powders. Microcrystalline powders were classified on the basis of their X-ray powder diffraction patterns. Their luminescent properties and magnetic properties were studied in the solid state. Intermetallic energy transfers were also discussed. Especially, for ligands H2hip and H2cpb. Hetero-nuclear compounds (Gd/Tb and Eu/Tb) were also prepared to tune luminescent properties by changing the relative ratios of the lanthanide ions. Lanthanide coordination polymers described in this thesis provide information that could be useful as far as multifunctional materials are targeted
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Sjöqvist, Jonas. "Luminescence properties of flexible conjugated dyes." Licentiate thesis, Linköpings universitet, Beräkningsfysik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-75191.
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In this licentiate thesis the luminescence properties of two flexible conjugated dyes have been studied. The first, Pt1, is a platinum(II) acetylide chromophore used in optical power limiting materials. The second is a set of optical probes known as luminescent conjugated oligothiophenes (LCOs), which are used to detect and characterize the protein structures associated with amyloid diseases such as Alzheimer’s disease. MM3 and CHARMM force field parameters have been derived for the Pt1 chromophore and LCOs, respectively, based on potential energy surface references calculated at the density functional theory (DFT)/B3LYP level of theory. The parameters have been used to perform room temperature molecular dynamics simulations of the chromophores in solvent, where tetrahydrofuran was used for Pt1 and water for the LCOs. Conformationally averaged absorption spectra were obtained, based on response theory calculations at the time-dependent DFT(TDDFT)/CAM-B3LYP level of theory for a selection of structures from the simulations. For one of the LCOs, p-HTAA, force field parameters were also created describing the dominant first excited state, based on TDDFT/B3LYP reference potential energy surfaces. These were used for molecular dynamics simulations of the chromophore in the excited state, allowing the creation of an emission spectrum. A theoretically obtained Stokes shift of 112 nm could be computed based on the absorption and emission spectra, which is in good agreement with the experimental value of 124 nm. In addition, a quantum mechanics/molecular mechanics study of the effects of solvation on the absorption properties of the p-HTAA chromophore in water has been conducted, resulting in two models for including these effects in the averaged spectra. The first includes explicit water molecules in the form of point charges and polarizable dipole moments, and results in an absorption wavelength that is blueshifted by 2 nm from a high quality reference calculation. The second model involves the complete removal of the solvent as well as the ionic groups of the chromophore. The resulting absorption wavelength is blueshifted by an additional 4 nm as compared to the first model, but requires only one fifth of the computational resources.
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Accorsi, Gianluca <1973>. "Trivalent lanthanide ions: luminescence and applications." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2007. http://amsdottorato.unibo.it/472/1/Accorsi_Gianluca_Tesi_di_Dottorato_XIX_Ciclo.pdf.
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Accorsi, Gianluca <1973>. "Trivalent lanthanide ions: luminescence and applications." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2007. http://amsdottorato.unibo.it/472/.
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Freitas, Carlos Eduardo. "Luminescência opticamente estimulada com aplicações em radioterapia: dependência da dose absorvida e da energia de fótons produzidos em aceleradores clínicos e Microtron - IFUSP." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-26052017-084002/.
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Atualmente a utilização de fótons de raios X e gama na Medicina (radiodiagnóstico e radioterapia) gerou a necessidade do conhecimento da dose absorvida nos tecidos dos pacientes. Para isso, utiliza-se detectores com diversas funcionalidades a fim de conhecer a deposição de energia. Para ser possível a utilização destes materiais, é necessário caracterizá-los tanto quanto à resposta em função da dose absorvida, quanto à dependência com a energia. Neste trabalho foi estudada a dependência energética da resposta OSL dos dosímetros compostos por BeO e Al2O3 em feixes de raios X convencional com espectro largo, feixes de raios X de aceleradores clínicos e do acelerador Microtron do Instituto de Física da USP e fontes gama de Cs-137 e Co-60, em uma faixa de doses desde centenas de mGy até aproximadamente 2 Gy. Foram utilizadas em conjunto simulações em Monte Carlo com o código PENELOPE, que simula o transporte de fótons e elétrons na matéria, a fim de conhecer a deposição de energia nos materiais. Os espectros utilizados nas simulações foram validados através da comparação das características dos feixes tais como a deposição de dose com a profundidade, camada semirredutora, energia média e resolução espectral. Utilizando um sistema de varredura por câmara de ionização controlado remotamente, foi estudada a distribuição de doses no campo de irradiação para definir uma região de irradiação com dose uniforme para pode realizar a irradiação de um conjunto de dosímetros simultaneamente. Foram encontrados valores do fator de dependência energética experimental para os feixes mais energéticos (Co-60, Microtron 5 MeV e aceleradores clínicos de 6 e 15 MeV), com desvio menor que 3% para o Al2O3 e 5% para o BeO, indicando independência com a energia do feixe de irradiação. Já nos feixes de baixa energia, os fatores de dependência energética relativos à energia do Co-60 para o Al2O3 foram de 1,68 e 1,42, e, para o BeO, de 0,78 e 0,90 para os feixes W150 e W200 respectivamente. Estes valores indicam que, nesta faixa de energia, a resposta OSL depende mais fortemente da energia do feixe. As simulações em Monte Carlo feitas para os fatores de dependência energética se mostraram bem consistentes com os valores experimentais para o BeO em toda faixa de energia e para o Al2O3, excetuando-se os feixes de baixa energia, possivelmente pelo não completo conhecimento de todos os elementos constituintes do dosímetro empregado (fita de Luxel®). Quanto às curvas de emissão OSL para as diferentes energias de irradiação, foi observado que o sinal decai mais rápido quanto mais elevada é a energia média do feixe para o BeO. Para o Al2O3, o efeito foi mais sutil e oposto. Os estudos do feixe do Microtron mostraram que, desde que a corrente seja monitorada durante as irradiações para posterior correção da dose, é possível realizar estudos utilizando um feixe de fótons de Bremsstrahlung produzido com alvo externo e energias médias (simuladas e ainda não validadas experimentalmente) próximas às energias das fontes gama de Cs-137 e Co-60. Os resultados experimentais para as respostas OSL dos dois materiais foram compatíveis com as simulações.Nowadays the use of X and gamma-ray photons in Medicine (radiodiology and radiotherapy) has generated the necessity of knowing the absorbed dose to the tissues of patients. For this purpose, detectors with diverse functionalities are used to know the energy deposition. To make possible the use of these materials, it is necessary to characterize the dose response, as well as the energy dependence of the response. In this work the energy dependence of the OSL response of the BeO and Al2O3 dosimeters was studied for conventional X-ray beams with wide energy spectrum, X-ray beams from clinical accelerators and from the Microtron accelerator of the Institute of Physics (University of São Paulo), and for gamma sources of Cs-137 and Co-60, in a dose range from hundreds of mGy to about 2 Gy. Monte Carlo simulations were used with the PENELOPE code, which simulates the photons and electrons transport of in the matter, to know the energy deposition in the materials. The energy spectra used in simulations were validated by comparison with beam characteristics such as depth dose deposition, half-value layer, mean energy and spectral resolution. Using a remotely controlled ionization chamber scanning system, the dose distribution within the irradiation field was evaluated to define a uniform dose region for irradiation or a set of dosimeters simultaneously. Experimental energy dependence factor values were obtained for the high-energy beams (Co-60, Microtron 5 MeV, and clinical accelerators of 6 and 15 MeV), with a deviation of less than 3% for Al2O3 and 5% for BeO, indicating independence with the beam energy. For the low-energy X-ray beams, the energy dependence factors, relative to the Co-60 energy, for Al2O3 were 1.68 and 1.42, and, for BeO, 0.78 and 0.90 for W150 and W200 beams respectively. These values indicate that, in this energy range, the OSL response depends on beam energy. Monte Carlo simulations for the energy dependence factors were consistent with experimental values for the BeO in entire energy range and for the Al2O3, with the exception of low energy beams, possibly due to the incomplete knowledge of all the elements that constitute the Luxel®. As for the shape of OSL emission curves for the different irradiation energies, it was observed that the signal decays faster the higher is the average beam energy for BeO. For Al2O3, the effect was more subtle and opposite. The Microtron beam scanning has shown that, as long as the current is monitored during irradiation for further dose-rate correction, it is possible to carry out studies using a beam of Bremsstrahlung photons produced with external target and mean energies (simulated but still not validated experimentally) close to the energies of the Cs-137 and Co-60 sources. The experimental results for the OSL responses of both materials were compatible with simulations.
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Allen, Timothy J. "The luminescence of a soyabean oil alkyd resin and the application of luminescence as a discriminating technique." Thesis, University of Reading, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.296697.
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Chowdhury, Sanchari. "Application of Luminescence Sensors in Oxygen Diffusion Measurement and Study of Luminescence Enhancement/Quenching by Metallic Nanoparticles." Scholar Commons, 2010. https://scholarcommons.usf.edu/etd/1599.
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The first part of this dissertation deals with the application of a luminescence quenching method to measure diffusion and permeation coefficients of oxygen in polymers. Most luminescence oxygen sensors do not follow linearity of the Stern-Volmer (SV) equation due to heterogeneity of luminophore in the polymer matrix, thus the complexity of data analysis is increased. To circumvent this limitation, inverted fluorescence microscopy is utilized in this work to investigate the SV response of the sensors at the micron-scale. In these diffusion experiments, oxygen concentration is measured by luminescence changes in regions with high SV constants and good linearity. Thus, we avoid numerical complexity of combining nonlinear SV equation with a diffusion model. This technique allows us to measure oxygen diffusion properties in different type of polymers like transparent, opaque, free-standing polymers and polymers that cannot be cast into free standing films and polymer composites.
In the second part of this thesis, we have explored the effect of Ag-Cu alloy nanoparticles on the emission intensity of luminophores at their close proximity. Alloy nanoparticles offer additional degrees of freedom for tuning their optical properties by altering atomic composition and atomic arrangement and thus can be an attractive option for manipulating signal of a wide range of luminophores. In this work, surface plasmon resonance spectrum of Ag-Cu alloy nanoparticles deposited by sputtering was easily tuned in wide wavelength range by varying one experimental condition- annealing temperature. Large metal enhanced luminescence for different luminophores viz Alexa Fluor 594 and Alexa Fluor 488 were achieved at the vicinity of Ag-Cu nanoparticles when maximum spectral overlap between SPR spectra of Ag-Cu nanoparticles and the emission and absorption spectra of the luminophores occur. We also studied the effect of composition of Ag-Cu nanoparticles synthesized by the polyol process on the luminescence of low quantum yield dye Cy3.
In the third part of this thesis, quenching effect of Cu nanoparticles on CdSe/ZnS nanocrystal quantum dots has been explored. As Cu nanoparticles have comparable dielectric properties with gold nanoparticles, they are expected to show similar quenching effects. It was found that Cu is an efficient quencher of fluorescence from CdSe/ZnS quantum dots and the quenching effect is due to resonance energy transfer from quantum dots to Cu nanoparticles.
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Fu, Wen Tian. "Luminescence des terres rares dans des borates caractérisés par une faible dimensionalité des interactions entre ions luminescents." Bordeaux 1, 1986. http://www.theses.fr/1986BOR10613.
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Etude des proprietes luminescentes des ions de terre rare dans des borates riches en b::(2)o::(3) ou en oxydes alcalins caracterises par une dimensionalite restrainte de l'assemblage des polyedres de coordination de la terre rare. Une nouvelle famille de phases ternaires a ete isolee de formule mlnb::(9)o::(16) )m::(3+)-srba, lanthanide). La luminescence des ions eu**(3+), tb**(3+) et eu**(2+) ainsi que la fluorescence de nd**(3+) ont ete etudiees
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Fu, Wen Tian. "Luminescence des terres rares dans des borates caractérisés par une faible dimensionalité des interactions entre ions luminescents." Grenoble 2 : ANRT, 1986. http://catalogue.bnf.fr/ark:/12148/cb37597711b.
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Lahoud, Marcelo Galindo [UNESP]. "Obtenção de espécies moleculares e supramoleculares a partir de reações de auto-montagem entre íons lantanídeos e moléculas orgânicas multilópicas." Universidade Estadual Paulista (UNESP), 2012. http://hdl.handle.net/11449/97913.
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Este trabalho apresenta a síntese e caracterização espectroscópica, estrutural, morfológica e térmica de cinco novos complexos mistos de terras raras contendo os ligantes succinato e 3,5-dicarbóxipirazolato. O foco central foi investigar a interação entre alguns íons de terras raras e esses ligantes dicarboxilatos, com ênfase nas propriedades luminescentes e suas relações com a estrutura dos complexos obtidos. A difração de raios X de monocristal revelou que os compostos são isoestruturais, constituídos de unidades binucleares discretas, de fórmula geral [TR2(dcpz)2(suc)(H2O)8](H2O)1.5 (TR = Eu, Gd, Tb, Dy e Y). Essas unidades crescem tridimensionalmente por meio de ligações de hidrogênio. Investigação espectroscópica dos complexos de Gd3+ e Y3+ mostraram que o nível tripleto dos ligantes está acima do nível emissor dos íons Eu3+, Tb3+ e Dy3+, o que possibilitou a ocorrência de efeito antena nesses sistemas. Sendo assim, emissões nas regiões do vermelho, verde e próxima ao branco foram observadas, respectivamente. As medidas de susceptibilidade magnética, realizadas sob a coordenação do Prof. Dr. Rafael Sá de Freitas do IF/USP de São Paulo, mostraram que o complexo de Y3+ apresentou ser diamagnético à temperatura ambiente. Quanto aos demais compostos da série, estes revelaram ser paramagnetos, com momentos magnéticos compatíveis com o momento dos spins dos íons isolados, o que está de acordo com o fato de serem dímeros isolados, não havendo, portanto, interação entre os spins
This work presents structural, morphological and thermal synthesis and spectroscopic characterization of five new rare earth complexes that contain succinate and 3,5-dicarboxypyrazolate ligands. The main focus was to investigate the interaction between rare earth ions and these dicarboxylate ligands, particularly the luminescence proprieties and their relation with the structure of the obtained complexes. The single crystal X-ray diffraction revealed that the compounds are isostructural, consisting of binuclear discrete units, their general formula being [TR2(dcpz)2(suc)(H2O)8](H2O)1.5 (TR = Eu, Tb, Dy, Gd, Y), These units grow three-dimensionally through hydrogen bonds. Spectroscopic investigation of the complexes Gd3+ and Y3+ showed that the triplet level of the ligands is above the emitting level of the ions Eu3+, Tb3+ e Dy3+, which enabled the occurrence of antenna effect in these systems. Thus, emissions in the red and green regions, as well as the one nexts to the white one, were observed, respectively. The magnetic susceptibility measurements, performed under the supervision of Professor Rafael Sá de Freitas, from IF/USP São Paulo, showed that the Y3+ complex is diamagnetic in room temperature. As to the other compounds of the series, these proved to be paramagnets, with magnetic moments compatible with the time of the spins of the isolated ions. This is consistent with the fact that they are isolated dimers. There is not, therefore, interaction between the spins
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Monteiro, Jorge Henrique Santos Klier [UNESP]. "Foto e eletroluminescência de complexos de samário, európio e gadolínio trivalentes com a beta-dicetona tta e o fosfinóxido quelante dppmo." Universidade Estadual Paulista (UNESP), 2010. http://hdl.handle.net/11449/97925.
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A síntese e o estudo da luminescência dos complexos [Ln(tta)3(dppmo)], sendo Ln = Sm3+, Eu3+ e Gd3+, tta = tenoiltrifluoroacetonato e dppmo = bis(difenilfosfino)metano dióxido são descritos neste trabalho. O ligante (dppmo) foi obtido através da oxidação do bis(difenilfosfino)metano (dppm) e utilizado como reagente para substituição das moléculas de água do aquo complexo [Ln(tta)3(H2O)2] precursor. A coordenação dos ligantes foi indicada pelo deslocamento para menores energias dos estiramentos dos grupos C=O e P=O. A estequiometria foi confirmada por titulação complexométrica da Ln3+ e análise elementar de carbono e de hidrogênio. A análise termogravimétrica indicou que não há perda de massa relativa a água e que o composto sintetizado possui uma boa estabilidade térmica. Através do espectro de emissão do complexo de gadolínio foi determinado o tripleto mais intenso do sistema em 1,840.104 cm-1. O espectro de emissão do complexo de európio apresenta transições 5D0 _ 7FJ (J = 0; 1; 2; 3 e 4) sendo a transição 5D0 _ 7F0 uma única linha indicando somente um sítio emissor sem centro de inversão. Do espectro de emissão foram determinados os parâmetros de intensidade _2, _4, R02 e Arad e a partir da curva de decaimento do estado emissor o tempo de vida (_) de 0,52 ms. A taxa de emissão total foi calculada a partir do inverso do tempo de vida e a eficiência quântica pela relação entre a taxa de emissão radiativa e não radiativa obtendo-se _ = 47%. O espectro de emissão do complexo de samário apresentou as linhas características 4G5/2 _ 6HJ (J = 5/2; 7/2; 9/2 e 11/2) sendo a transição 4G5/2 _ 6H9/2 de maior intensidade no espectro. O aumento do tempo de vida do estado emissor indica que as perdas por processos não-radiativos são minimizadas em relação ao aquo complexo precursor. Foram determinadas: geometria teórica utilizando o modelo Sparkle / AM1...
The synthesis and the luminescence study of complexes [Ln(tta)3(dppmo)], with Ln = Sm3+, Eu3+ and Gd3+, tta = thenoyltrifluoroacetonate and dppmo = bis(diphenylphosphine)methane dioxide are reported. The ligand (dppmo) was obtained by oxidation of bis(diphenylphosphine)methane and used as reagent to substitute the water molecules of aquo complex precursor [Ln(tta)3(H2O)2]. The ligand coordination was showed by the shift to low wavenumbers of C=O and P=O stretchings. The stoichiometry was confirmed by complexometric titration of Ln3+ and elemental analysis of carbon and hydrogen. The thermogravimetric analysis showed that there is no water molecules weight loss and that the complex has a good thermal stability. The most intense triplet of the system was determined in 1.804x104 cm-1 through the gadolinium emission spectrum. The europium complex emission spectrum presented the transitions 5D0 _ 7FJ (J = 0; 1; 2; 3 and 4) with only one line for transition 5D0 _ 7F0 showing that there is only one noncentrossymetric site. The intensity parameters _2, _4, R02 and Arad were determined from emission spectrum while the lifetime (_) was determined from decay curve and its value is 0.53 ms. The total emission rate was calculated from the inverse of lifetime and the quantum efficiency by relation between radiative emission rate and total emission rate obtaining _ = 47%. The emission spectrum of samarium complex presented the transitions 4G5/2 _ 6HJ (J = 5/2; 7/2; 9/2 and 11/2) with the most intense transition 4G5/2 _ 6H9/2 one. The lifetime increasing compared with that of aquo complex precursor shows that the non-radiative quenching is minimized. The ground state geometry and theoretical UV-vis absorption spectrum were determined using the Sparkle / AM1 implemented in Mopac2009 package. Transfer and back transfer energy rates from ligand to rare earth, the population of fundamental singlet, excited... (Complete abstract click electronic access below)
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Sobrinho, Josiane Aparecida [UNESP]. "Fotocromismo e luminescência de compostos a base de tungstênio e íons terras raras trivalentes via síntese hidrotérmica." Universidade Estadual Paulista (UNESP), 2015. http://hdl.handle.net/11449/124471.
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000827107.pdf: 3859605 bytes, checksum: d84f269b80fe58ae033c498302383181 (MD5)Sistemas contendo elementos terras raras possuem diversas aplicações em função de suas propriedades espectroscópicas e magnéticas. Já compostos à base de tungstênio formam uma grande classe de materiais inorgânicos que exibem propriedades físicas interessantes, em especial as fotocrômicas. Dentre os compostos de W6+, destaca-se o óxi-hidróxido de tungstênio e íons terras raras, com fórmula geral TRW2O6(OH)3, sobre o qual encontram-se poucos relatos na literatura. Desta forma, o objetivo deste trabalho é avaliar as propriedades estruturais e espectroscópicas de óxi-hidróxidos de tungstênio e cátions trivalentes de elementos terras raras sintetizados por via hidrotérmica, método pelo qual a fase é facilmente obtida. A adição de ácido cítrico às sínteses leva a grande controle na morfologia das partículas obtidas e, mesmo permanecendo como resíduo nas amostras em que é utilizado, não causa distorções significativas na estrutura cristalina. Além disso, o aditivo promove a redução dos íons W6+ ao estado de oxidação (V), o que tem grande influência sobre as propriedades ópticas da fase em estudo. Os dados de reflectância difusa mostram uma intensa banda de absorção que se estende por todo o visível e infravermelho próximo, atribuída à transições de transferência de carga intervalência (IVCT) entre íons W5+ e W6+ adjacentes. A irradiação do material com energia que exceda ao bandgap leva ao aumento da banda associada à IVCT e consequente mudança de coloração do material, o que indica a ocorrência de fotocromismo; quando a excitação é feita na região do ultravioleta, o efeito fotocrômico é realçado pela fotodecomposição dos resíduos de ácido cítrico. O aumento da banda associada à IVCT leva, concomitantemente, à supressão da emissão a partir do nível emissor 5D0 dos íons Eu3+, resultando em um perfil exponencial de diminuição da...
Systems containing rare earth elements have many applications due to their spectroscopic and magnetic properties. On the other hand tungsten-based compounds form a large class of inorganic materials which exhibit interesting physical properties, particularly photochromism. Among W6+ compounds, oxy-hydroxide containing tungsten and rare earth ions, with formula TRW2O6(OH)3, stands out with few reports in the literature. Thus, the aim of this study is to evaluate the structural and spectroscopic properties of oxy-hydroxides with tungsten and trivalent cations of rare earth elements, synthesized via hydrothermal method, by which the phase is easily obtained. The addition of citric acid to the synthesis leads to effective control of particles morphology, and even remaining as a residue in samples in which it is employed, it does not cause significant distortion of the crystal structure. Furthermore, this additive promotes the reduction of W6+ ions to the oxidation state (V), which has a great influence on the optical properties of the studied phase. The reflectance data show an intense absorption band which extends over the entire visible and near infrared spectral range, assigned to the intervalence charge transfer transitions (IVCT) between W5+ and adjacent W6+ ions. Irradiation of the material with energies exceeding the bandgap leads to an increase in the band associated with the IVCT and subsequent color change of the material, which indicates the occurrence of photochromism; when the excitation is done in the ultraviolet spectral region, the photochromic effect is enhanced by the photodecomposition of citric acid residues. The increased bandwidth associated with the IVCT leads concomitantly to the suppression of emissions from Eu3+ 5D0 emitting level, resulting in an exponential decrease of the emission intensity profile as the material is continuously irradiated. This observation suggests that...