Dual-Band Plasmonic Enhancement of Ag-NS@SiO2 on Gain Medium’s Spontaneous Emission
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We present a theoretical study on plasmonic enhancement of molecular fluorescence near a nanocomposite, Ag nanoshell (Ag-NS) coated by a gain medium of molecule-doped SiO2 layer. We use an average enhancement factor (AEF), which considers contributions from all possible orientations and locations of molecules in the silica layer to estimate the overall performance of Ag-NS@SiO2 at specific excitation and emission wavelengths. Our results on the AEF reveal that Ag-NS@SiO2 is a dual-band enhancer on the spontaneous emission of the gain medium; one is a narrowband in a shorter wavelength regime (quadrupole mode) and the other is a broadband in a longer wavelength regime (dipole mode). These two bands are tunable by adjusting the core size and the thickness of the Ag shell. Due to this merit, Ag-NS@SiO2 has great potentials to enhance Forster resonance energy transfer between a donor and a corresponding acceptor with large Stokes shifts.
KeywordsNanoshell Excitation rate Apparent quantum yield Fluorescence Average enhancement factor Bonding mode Quadrupole mode Dipole mode Forster resonance energy transfer
The research was supported by the National Science Council, Taiwan, R.O.C. (NSC 97-2221-E-182-012-MY2, 99-2221-E-182-030-MY3, 99-2221-E-002-034).
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