Avaliação do aumento da luminescência dos detectores CaF2 através da deposição de nanopartículas metálicas

• Ano de defesa: 2024
• Autor(a) principal: Aguiar, Guilherme de Mello
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Tecnológica Federal do Paraná; Curitiba; Brasil; Programa de Pós-Graduação em Física e Astronomia; UTFPR
• Palavras-chave em Português: Luminescência opticamente estimulada; Dosímetros; Nanopartículas metálicas; Fluoreto de Cálcio; Radiação ionizante; Optically stimulated luminescence; Dosimeters; Metallic nanoparticles; Calcium fluoride; Ionizing radiation; CNPQ::CIENCIAS EXATAS E DA TERRA::FISICA; Física
• Link de acesso: http://repositorio.utfpr.edu.br/jspui/handle/1/36406

The presence of nanoparticles (Nps) deposited on the surface of Optically Stimulated Luminescence (OSL) dosimeters may affect their luminescent efficiency. An increase in OSL intensity in these detectors can be achieved by depositing metallic nanoparticles (M-Nps) on their surface due to the Localized Surface Plasmon Resonance (LSPR) effect. LSPR is characterized by an electromagnetic field around the Nps that is highly dependent on the geometry, size, and material of the Nps. The excitation rate of the luminescence generated by X-rays is enhanced by the local field near the surface of the Nps under surface plasmon resonance conditions, resulting in an increase in luminescence. The objective of this work was to evaluate the OSL and RL in detectors made with Calcium Fluoride (CaF¢) decorated with metallic nanoparticles. For these purposes, OSL films were produced based on Brazilian natural calcium fluoride (CaF¢) with M-Nps (Ag, Au, Bi, Cu, and Pb) deposited on the surface of the films using the spin-coating technique at various speeds (3000 RPM, 4000 RPM, 5000 RPM, and 6000 RPM). The OSL efficiency was obtained by comparing the OSL response of samples with and without Nps, previously exposed to the same dose. The readings and irradiations were performed on the automatic Risø TL/OSL reader equipped with a beta 90Sr/90Y source (11 mGy/s). Additionally, the influence of the deposited volume of NP solution (400 ¿L, 600 ¿L, and 800 ¿L) on the OSL response was evaluated. Considering the rotation speed in position, the best results were obtained at 4000 RPM. Regarding the deposited volume, taking into account the associated uncertainties, no significant variations in the signal were observed. All detectors with added M-Nps, compared to those without Nps, showed an increase in OSL efficiency (1% to 15%). The detectors with CuNP and PbNP showed the largest increases, ranging between 10% and 15%. Based on the results obtained in this study, we conclude that the increase in OSL efficiency is due to both the amplification of optical stimulation and the enhancement of the OSL signal emitted by CaF¢, which is a surface effect induced by surface plasmon resonance. The increase in RL signal intensity in samples with metallic nanoparticles (Nps-M) is due to the LSPR effect, which enhances the electromagnetic field on the surface of the Nps, amplifying luminescence. Additionally, CaF¢ detectors with Nps-M showed an increase of over 25% in the RL signal, demonstrating greater efficiency compared to detectors without Nps-M.