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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Vibrational spectroscopy in crystals of trans-cinnamic acid complexed with Europium under extreme conditions / Espectroscopia vibracional em cristais do Ãcido trans-cinÃmico complexado com eurÃpio sob condiÃÃes extremas

Josà Enedilton Medeiros Pereira 16 July 2014 (has links)
This work is focused on characterization of a polycrystalline sample of the coordination compound with ions Eu3+ using as a binder the trans-cinnamic acid , [Eu(cin)3]. The interest in coordination with lanthanide compounds is due to their large technological applications. The process of luminescence of coordination compounds containing lanthanide, also called antenna effect, has a main objective the use of new ligands with various applications, both in increasing the efficiency of energy receptors in the ultraviolet region and the development of biomarkers. In this work, to characterize the polycrystalline material, Raman spectroscopy was used to determine the vibrational behavior of the material at ambient temperature and pressure. It was also shown the behavior of the compound at low temperatures, in which variations in various vibrational modes were observed, indicating thus the occurrence of phase transition. Using a diamond anvil cell the material was studied by high hydrostatic pressure Raman spectroscopy. The purpose of this methodology was to map possible phase transitions and discover the occurrence of possible polymorphism. However, until the pressure reached in the experiments - about 5.2 GPa - it was found that the original phase remained stable. A discussion of the luminescence of the sample is also provided in this work. / O presente trabalho està focado na caracterizaÃÃo de uma amostra policristalina do composto de coordenaÃÃo com Ãons Eu3+ utilizando como ligante o Ãcido trans-cinÃmico, [Eu(cin)3]. O interesse em compostos de coordenaÃÃo com lantanÃdeos deve-se Ãs suas amplas aplicaÃÃes tecnolÃgicas. O processo de luminescÃncia dos compostos de coordena- ÃÃo contendo lantanÃdeo, tambÃm chamado de efeito antena, tem como principal objetivo o uso de novos ligantes com aplicaÃÃes diversas, tanto no aumento da eficiÃncia de re- ceptores de energia na regiÃo do ultravioleta quanto no desenvolvimento de marcadores biolÃgicos. Neste trabalho, para realizar a caracterizaÃÃo do material policristalino, foi utilizada a espectroscopia Raman, a fim de determinar o comportamento vibracional do material à temperatura e pressÃo ambiente. TambÃm foi verificado o comportamento do composto sob baixas temperaturas, no qual foram observadas variaÃÃes em vÃrios modos vibracionais, indicando, por conseguinte, a ocorrÃncia de transiÃÃo de fase. Utilizando uma cÃlula de pressÃo a extremos de diamante o material foi estudado a altas pressÃes hidrostÃticas atravÃs de espectroscopia Raman. O intuito desta metodologia era mapear possÃveis transiÃÃes de fase e descobrir a ocorrÃncia de eventual polimorfismo. Entretanto, atà a pressÃo atingida nos experimentos â cerca de 5,2 GPa â verificou-se que a fase ori- ginal permaneceu estÃvel. Uma discussÃo sobre a luminescÃncia da amostra tambÃm à fornecida neste trabalho.

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