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Doctoral Thesis
DOI
10.11606/T.43.1989.tde-24022014-105143
Document
Author
Full name
Luiz Antonio Ribeiro da Rosa
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 1989
Supervisor
Committee
Caldas, Linda Viola Ehlin (President)
Ghilardi Netto, Thomaz
Las, Wanda Cecilia
Lipsztein, Joyce Lederman
Matsuoka, Masao
Title in Portuguese
Termoluminescência do LiF: Mg, Ti entre 77 e 315 k.
Keywords in Portuguese
Termoluminescência
Abstract in Portuguese
Desenvolveu-se um sistema termoluminescente especial, para operar a partir da temperatura do nitrogênio líquido, que permite, ainda, a obtenção do espectro de emissão termoluminescente da amostra. Com o uso deste sistema, estudou-se a termoluminescência do LiF:Mg,Ti (TLD-100), irradiado a 77 K, desde a temperatura de irradiação até 315K. Neste intervalo de temperaturas foram determinados sete picos de emissão termoluminescente em 139, 153, 194, 240, 260, 283 e 300K. Através de experiências de variação do tratamento térmico da amostra, linearidade, fototransferência e destruição óptica, o pico de emissão termoluminescente em 139K foi associado a centros de buracos Vk, enquanto que os demais a armadilhas de elétrons. Os sete picos de emissão termoluminescente emitem em três comprimentos de onda, 270, 300 e 420nm, sendo que a banda de emissão em 270nm é a mais intensa no caso dos picos de emissão termoluminescente em 139 e 153K, sobressaindo-se as bandas de emissão em 300 e 420nm para os demais picos de emissão termoluminescente. A banda de emissão em 270nm foi associada a centros de recombinação para buracos liberados dos centros Vk, centros estes diferentes daqueles, normalmente, associados à banda de emissão em 420nm. Quanto à banda de emissão em 300nm, esta foi associada à interação entre elétrons e centros Vk. Verificou-se que os picos de emissão termoluminescente em 139, 153, 194 e 260K obedecem à cinética de primeira ordem. As energias de ativação determinadas para estes picos foram, respectivamente, 0,26, 0,29, 0,49 e 0,82eV.
Title in English
Thermoluminescence of LiF: Mg, Ti between 77 and 315 k.
Keywords in English
Thermoluminescence
Abstract in English
A special thermoluminescent system was deve1oped. It is able to operate right from liquid nitrogen temperature and also permits the determination of the sample thermoluminescent emission spectrum. Using this system, the thermoluminescence displayed by 77K irradiated LiF:Mg,Ti (TLD-100), from the irradiation temperature to 315 K, was studied. In this temperature range seven glow peaks, at 139, 153, 194, 240, 260, 283 and 300 K, were determined. Based upon different annealing procedures, linearity, phototransference and optical bleaching experiments, the glow peak at 139 K was related to Vk hole centres, while the remaining glow peaks were associated to electron traps. The seven glow peaks emit at three wavelengths, namely, 270, 300 and 420 nm. The emission band at 270 nm is the most intense in the case of glow peaks at 139 and 153 K. For the remaining glow peaks, the emission bands at 300 and 420 nm are the most important ones. The emission band at 270 nm was related to the recombination of Vk holes at recombination centres other than those ones, normally, associated to the emission band at 420 nm. The emission band at 300 nm was related to the recombination of electrons and Vk centres. It was verified that the glow peaks at 139, 153, 194 and 260 K obey the first order kinetics. For these glow peaks, the determined activation energies were, respectively, 0,26, 0,29, 0,49 and 0,82 eV.
 
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RE40106Rosa.pdf (62.21 Mbytes)
Publishing Date
2014-02-24
 
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