Near-field coupling of silver nanoparticle and silver island on metal-enhanced fluorescence
Date Issued
2015
Date
2015
Author(s)
Wu, Hsin-Yu
Abstract
The metal enhanced fluorescence (MEF) of a silver island (SI) associated with a silver nanoparticle (SNP) was studied in this thesis. The coupling plasmonic effect of the hybrid nanostructure can enhance the near field within the gap zone. We use the multiple multipole method to analyze the plasmon-mediated enhancement factor on the fluorescence of a molecule located in the gap zone, where the SI is modelled as an oblate spheroid. The fluorescent molecules used for simulation in this study are TRITC and Texas red. We quantitatively analyzed the MEF effects with different gaps, the incident angles of plane wave, and the sizes and shapes of SI and SNP. Numerical results show that the enhancement factor of the hybrid nanostructure on MEF is higher than that of a SI alone due to the coupled gap mode; the smaller the gap the larger the enhancement factor. This finding is in agreement with the previous experimental results. In addition, reducing the distance between molecule and SNP can also raise MEF. The surface plasmon resonance (SPR) band of the SI is red-shifted and broadened by being flattened or enlarged. This property allows us to tailor the shape of SI for obtaining the maximum excitation rate on a specific molecule. Moreover, we found that the induced optical force allows SNP be attracted by SI to reduce the gap gradually for performing a stronger MEF effect
Subjects
metal enhancement fluorescence(MEF)
silver island
silver nanoparticle
multiple multipole (MMP) method
surface plasmon resonance (SPR)
gap
excitation rate
quantum yield
enhancement factor
optical force
Type
thesis
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