The Plasmon Resonance of a Multilayered Gold Nanoshell and its Potential Bioapplications

Dept. of Electr. Eng., Shanghai Jiao Tong Univ., Shanghai, China
IEEE Transactions on Nanotechnology (Impact Factor: 1.8). 08/2011; DOI: 10.1109/TNANO.2010.2079943
Source: IEEE Xplore

ABSTRACT The optical spectra and near-field enhancement of a multilayered gold nanoshell were theoretically studied in this paper to explore its potential biological applications. The mathematical model was developed within the framework of multipole expansion of a multilayered concentric sphere. Results show that compared with a conventional single-layered Au-SiO2 nanoshell, a multilayered Au-SiO2-Au nanoshell has an advantage of realizing the localized surface plasmon resonance at wavelength of 1300 nm or longer, which is believed to be more beneficial to ultrahigh resolution optical coherent imaging. With single-layered nanoshell, an extremely thin gold layer is required for resonance at long wavelength, and making such thin layer would be almost practically impossible within the current synthesis techniques.

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    ABSTRACT: The multilayer nanoshells symmetry breaking makes otherwise dark higher order modes visible and interacting with the dipole mode. Fano resonance could be accomplished through interferences between these modes. Here we propose a structure based on three shells of different materials (silver, silica and gold) and study the near and far field optical properties. The resonant peaks of extinction and near field enhancement can be tuned and enhanced by offsetting the layers compared to the concentric geometry nanoshell respectively. By displacing the silica shell from the center, higher order dark modes appear in the spectrum predominantly compared to the silver-core and the outer gold-shell offset.

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