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| Author(s): |
Éder José Guidelli
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Ribeirão Preto. |
| Institution: | Universidade de São Paulo (USP). Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto (PCARP/BC) |
| Defense date: | 2015-04-27 |
| Examining board members: |
Oswaldo Baffa Filho;
Noelio Oliveira Dantas;
Antonio Carlos Hernandes;
Marcelo Mulato;
Shigueo Watanabe
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| Advisor: | Oswaldo Baffa Filho |
| Abstract | |
Optically stimulated luminescence (OSL) is a well-known light emission process involving light stimulation of an insulator/semi-conductor material previously exposed to ionizing radiation. The intensity of the emitted light is proportional to the ionizing radiation dose previously absorbed by the material. Developing appropriate OSL materials for radiation detection and dosimetry is based on the doping and co-doping of a host material to create defects that can act as traps and/or luminescent centers. In this context, plasmon interaction with luminescent centers from OSL materials could be a new, different, and unexplored method to achieve enhanced OSL intensity and consequently improve their sensitivity as radiation detectors. In this study, we investigated whether it is possible to use the plasmonic properties of noble metal nanoparticles to obtain plasmon-enhanced OSL. To this end, we produced samples of NaCl containing nano and microparticles; composites of ZnO containing silver and gold nanoparticles; as well as samples of NaCl deposited over films of gold and silver nanoparticles. Each sample has been tested as a radiation detector by means of optically stimulated luminescence, in addition to having their materials properties analyzed by UV-Vis absorption spectroscopy, dynamic light scattering, transmission electron microscopy (TEM), atomic force microscopy, and Fourier Transform Infrared spectroscopy (FTIR). We discovered that the electric field intensification around nanoparticles under plasmon resonance conditions enhances the excitation rate of trapped electrons. The plasmon coupling during the emission process increases the radiative and diminishes the non-radiative decay rates, leading to enhanced OSL intensities. Furthermore, the interaction between traps/luminescent centers and plasmons is highly dependent on the distance between them, and the maximum OSL intensity was observed for samples with 15 nm spacing between the NaCl and the silver nanoparticle films. Therefore, it is possible to use the plasmon properties of metal nanostructures to increase OSL, giving rise to new and more sensitive ionizing radiation detectors and dosimeters. (AU) | |
| FAPESP's process: | 11/09521-8 - Optically stimulated luminescence under plasmon resonance conditions |
| Grantee: | Éder José Guidelli |
| Support Opportunities: | Scholarships in Brazil - Doctorate |