Caracterização óptica de vidros fosfato dopados com íons emissores terras-raras de Nd3+, Er3+ e Pr3+ e de pontos quânticos coloidais CdSe/ZnS

• Ano de defesa: 2013
• Autor(a) principal: Martins, Vanessa Menezes
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Uberlândia; BR; Programa de Pós-graduação em Física; Ciências Exatas e da Terra; UFU
• Palavras-chave em Português: Vidros; Íons terras raras; Lente térmica; Pontos quânticos CdSe/ZnS; Transferência de energia; Íons; Pontos quânticos; Glasses; Rare earth ions; Thermal lens; Quantum dots CdSe / ZnS; Energy transfe; CNPQ::CIENCIAS EXATAS E DA TERRA::FISICA
• Link de acesso: https://repositorio.ufu.br/handle/123456789/15612

In this work we have studied some of the optical and thermal properties of two different systems. The first being a phosphate glass (called PAN) doped separately with different concentrations of rare earth ions of Nd3+, Er3+ and Pr3+. And the second system contain colloidal quantum dots CdSe/ZnS with different sizes. We began our studies with a PAN:Nd3+ set of samples. In this context, we performed an analysis of the parameters related to the radiative properties such as lifetime radiative and quantum efficiency of luminescence, η, using the Judd Ofelt theory. In addition, we performed measurements of the excited state absorption, and a more detailed study of the energy transfer between the ions, which were evaluated by the micro parameters CDA and CDD. Finally concluding our studies in PAN:Nd3+ glasses, we performed microluminescence measurements. For the PAN:Er3+ samples, it were also calculated parameters related to the radiative properties using the Judd Ofelt theory. With the aid of the technique of Thermal Lens and Judd Ofelt theory it was calculated the values of η. Through an analysis of cross sections emission and lifetime it was possible to see the potential applicability of PAN:Er3+ glass in optical amplifiers. Finally in the PAN:Pr3+ glass we obtained basic spectroscopy measurements such as optical absorption, emission and lifetime. Measurements of microluminescence were also performed, in order to check the energy migration length depending on the concentration of Pr3+ to different wavelengths, so far unknown in literature. All results obtained in this study were analyzed as a function of dopant concentration, and in general, it was found that the PAN glass doped with rare earth ions have a good combination of optical and thermal properties, which are essential for potential applications in optical devices. For the second system (quantum dots CdSe/ZnS), we proposed a model for the thermal loading, whence is possible to estimate the efficiency of energy transfer (ηTE) between two quantum dots with different sizes. In this aspect through estimates and considering the values of η for each individual quantum dot, we were able to determine ηTE. These results are of great relevance, since there are still no reports in the literature of ηTE study between colloidal quantum dots using as a tool the thermal lens technique.