Termoluminescência e luminescência opticamente estimulada da calcita natural amarela
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Data
2022-06-29
Autores
Guilheiro, Joice Marques [UNIFESP]
Orientadores
Tatumi, Sonia Hatsue [UNIFESP]
Tipo
Tese de doutorado
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Objetivos: Caracterização da estrutura cristalina da amostra de calcita, com a finalidade de possível uso na dosimetria ambiental e datação geológica. Métodos: Para caracterizar a estrutura cristalina do mineral, foram realizados os testes de DRX, de TL e de LOE, para o estudo da termoluminescência na luz visível e no espectro UV e o teste de fotoluminescência. Resultados: O teste de DRX demonstraram compatibilidade da amostra do estudo com estrutura a calcita. A emissão de TL foi detectada no espectro UV e espectro visível, com picos detectados em 92,9, 118,9 e 150 ºC. Ambos os espectros apresentaram boa resposta à irradiação beta entre 5 Gy e 41 Gy. Na região UV, a TL resultou picos em 90 ºC e 125 ºC. Todos os picos aumentam com a irradiação beta. Os experimentos de branqueamento demostraram que a emissão de LOE estar relacionados aos picos de baixas temperaturas detectados na TL. Protocolos de doses aditivas para emissão de LOE apresentam crescimento linear para doses acima de 100 Gy e o resultado da amostra de regeneração total de curva apresentou uma boa resposta a dose de 4,3 Gy. A LOE de calcita também aumenta com a radiação e sua emissão da LOE pode ser correlacionada com os picos da TL de 90 ºC e 125 ºC. Os resultados das medidas do espectro de emissão com estímulos em 350 nm, exibidos em 4 bandas largas em 413, 440, 470 e 486 nm e, uma pequena banda de 300 nm, que podem ser associadas com as vacâncias de oxigênio e defeitos em Me-O. Através da análise do diagrama CIE, provou-se que a radiação promove uma mudança na cor emitida pela amostra de azul para púrpura-azulado. Conclusão: A amostra analisada neste trabalho apresentou emissões luminescentes tanto na TL quanto na LOE, tornando possível seu uso na dosimetria de radiações ionizantes.
Background: To caracterize crystalline structure of yellow calcite sample, with a purpose to use in environmental dosimetry and geological dating. Methods: XRD measurement was performed to verify the crystalline structure of the sample. TL UV and Vis spectrum, OSL UV and Vis spectrum, and photoluminescence emission measurements were performed. Results: XRD confirmed that sample has calcite crystalline structure. TL emission was detected with peaks at 92,9, 118,9, and 150 ºC. All peaks responded in the range between 5 and 41 Gy. In TL region UV, presented two peaks, at 90 ºC and 125 ºC, and it increased with beta irradiation. The bleaching experiments demonstrated that OSL emission was related with low temperature peaks. Ad- ditive dose protocol for OSL emission showed linear growth up to a dose about 100 Gy, and in the result of the total regeneration curve the sample showed a reasonable response to a dose of 4,3 Gy. The OSL responded growth up with radiation, and your emission can be associated with TL peaks at 90 ºC and 125 ºC. The results of PL with excitation at 350 nm, exhibited four broad bands at 413, 440, 470, and 486 nm, and a small one at 300 nm, which can be associated with oxygen vacancies and Me–O defects. Through the analysis of the CIE diagrams, it was proven that the irradiation promoted a change in the color emitted by the sample from blue to purplish blue. Conclusion: The sample analyzed in this present work showed emissions in both TL and LOE, which makes the sample usable in the dosimetry of ionizing radiation.
Background: To caracterize crystalline structure of yellow calcite sample, with a purpose to use in environmental dosimetry and geological dating. Methods: XRD measurement was performed to verify the crystalline structure of the sample. TL UV and Vis spectrum, OSL UV and Vis spectrum, and photoluminescence emission measurements were performed. Results: XRD confirmed that sample has calcite crystalline structure. TL emission was detected with peaks at 92,9, 118,9, and 150 ºC. All peaks responded in the range between 5 and 41 Gy. In TL region UV, presented two peaks, at 90 ºC and 125 ºC, and it increased with beta irradiation. The bleaching experiments demonstrated that OSL emission was related with low temperature peaks. Ad- ditive dose protocol for OSL emission showed linear growth up to a dose about 100 Gy, and in the result of the total regeneration curve the sample showed a reasonable response to a dose of 4,3 Gy. The OSL responded growth up with radiation, and your emission can be associated with TL peaks at 90 ºC and 125 ºC. The results of PL with excitation at 350 nm, exhibited four broad bands at 413, 440, 470, and 486 nm, and a small one at 300 nm, which can be associated with oxygen vacancies and Me–O defects. Through the analysis of the CIE diagrams, it was proven that the irradiation promoted a change in the color emitted by the sample from blue to purplish blue. Conclusion: The sample analyzed in this present work showed emissions in both TL and LOE, which makes the sample usable in the dosimetry of ionizing radiation.
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Citação
GUILHEIRO, Joice Marques. Termoluminescência e luminescência opticamente estimulada da calcita natural amarela. 2022. 56 f. Tese (Doutorado Interdisciplinar em Ciências da Saúde) - Instituto de Saúde e Sociedade, Universidade Federal de São Paulo, Santos, 2022.