Publicação
Pulsed-laser fabrication of gold plasmonic nanoparticles in thin films for LSPR sensing applications
| Resumo: | We demonstrate a controlled method for forming plasmonic gold nanoparticles in ZnO thin films using pulsed laser annealing with real-time optical monitoring. Gold nanoparticles with an average radius of 3 nm were initially embedded in sputtered ZnO films on fused silica substrates. Using 532 nm pulses from a Q-switched Nd:YAG laser (20 - 40 mJ, 10 Hz), we induced controlled annealing while simultaneously monitoring transmission spectra via an in-situ broadband spectrometer. After about 10 to 100 laser pulses, depending on the location on the sample’s surface, a plasmonic resonance dip emerged at approximately 550 nm, deepening and broadening with continued exposure. The process stabilized after 300 to 400 shots, producing larger nanoparticles (20 - 200 nm diameter) partially protruding from the ZnO surface. SEM analysis confirmed significant particle coarsening and migration toward the film surface. Numerical simulations were developed to correlate the observed spectral evolution with nanoparticle size and embedding depth, and a complementary temperature model indicated that local heating during laser irradiation can reach values sufficient to promote melting and coalescence. This approach demonstrates effective control over plasmonic nanostructure formation for sensing applications, providing advantages over conventional thermal annealing through spatial selectivity, rapid processing and real-time process monitoring. |
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| Autores principais: | Sousa, Edgar Barros |
| Assunto: | Pulsed laser annealing LSPR Plasmonic nanoparticles Gold nanoparticles Spectrometry Nanocomposite thin films Recozimento com laser pulsado Nanopartículas plasmónicas Nanopartículas de ouro Espetrometria Filmes finos nanocompósitos Ciências Naturais::Ciências Físicas |
| Ano: | 2025 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade do Minho |
| Idioma: | português |
| Origem: | RepositóriUM - Universidade do Minho |
| Resumo: | We demonstrate a controlled method for forming plasmonic gold nanoparticles in ZnO thin films using pulsed laser annealing with real-time optical monitoring. Gold nanoparticles with an average radius of 3 nm were initially embedded in sputtered ZnO films on fused silica substrates. Using 532 nm pulses from a Q-switched Nd:YAG laser (20 - 40 mJ, 10 Hz), we induced controlled annealing while simultaneously monitoring transmission spectra via an in-situ broadband spectrometer. After about 10 to 100 laser pulses, depending on the location on the sample’s surface, a plasmonic resonance dip emerged at approximately 550 nm, deepening and broadening with continued exposure. The process stabilized after 300 to 400 shots, producing larger nanoparticles (20 - 200 nm diameter) partially protruding from the ZnO surface. SEM analysis confirmed significant particle coarsening and migration toward the film surface. Numerical simulations were developed to correlate the observed spectral evolution with nanoparticle size and embedding depth, and a complementary temperature model indicated that local heating during laser irradiation can reach values sufficient to promote melting and coalescence. This approach demonstrates effective control over plasmonic nanostructure formation for sensing applications, providing advantages over conventional thermal annealing through spatial selectivity, rapid processing and real-time process monitoring. |
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