Paper
11 September 2006 Plasmonic substrates for surface-enhanced spectroscopies
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Abstract
Using the Plasmon Hybridization (PH) method and the Finite-Difference Time-Domain (FDTD) method, we investigate the plasmonic properties of finite metallic nanopartices interacting with extended metallic substrates such as thin films and wires. The results from the two computational methods are found to agree very well. We show that the plasmons of a metallic nanoparticle couple to the delocalized plasmons of extended substrates in the same manner as an electronic impurity level couples to an continuum of electronic states. The interaction can result in both localized plasmons and virtual states in the plasmonic continuum. The virtual states are composed of delocalized plasmons from the extended substrate and depend sensitively on the geometry of the system, the polarization of incident electromagnetic excitations as well as the background dielectric properties of the structures. We demonstrate that the virtual state can provide large electric field enhancements over a broad and tunable spectral regime. Our investigations show that plasmonic structures supporting virtual states are highly suitable as substrates for surface enhanced spectroscopic applications and may be useful in plasmonic waveguiding applications.
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F. Le, F. Hao, and P. Nordlander "Plasmonic substrates for surface-enhanced spectroscopies", Proc. SPIE 6324, Plasmonics: Nanoimaging, Nanofabrication, and their Applications II, 63240P (11 September 2006); https://doi.org/10.1117/12.682195
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KEYWORDS
Plasmons

Plasmonics

Dielectrics

Finite-difference time-domain method

Nanoparticles

Absorption

Optical spheres

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