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Effect of the Dielectric Constant of the Surrounding Medium and the Substrate on the Surface Plasmon Resonance Spectrum and Sensitivity Factors of Highly Symmetric Systems: Silver Nanocubes
journal contribution
posted on 2012-04-11, 00:00 authored by Mahmoud
A. Mahmoud, Maysamreza Chamanzar, Ali Adibi, Mostafa A. El-SayedSilver nanocubes (AgNCs), 60 nm, have four extinction
surface plasmon
resonance (SPR) peaks. The finite difference time domain (FDTD) simulation
method is used to assign the absorption and scattering peaks and also
to calculate the plasmon field intensity for AgNCs. Because AgNCs
have a highly symmetric cubic shape, there is a uniform distribution
of the plasmon field around them, and they are thus sensitive to asymmetric
dielectric perturbations. When the dielectric medium around a nanoparticle
is changed anisotropically, either by placing the particle on a substrate
or by coating it asymmetrically with a solvent, the plasmon field
is distorted, and the plasmonic absorption and scattering spectra
could shift differently. For the 60 nm AgNC, we found that the scattering
resonance peak shifted more than the absorption peak. This changes
the extinction bandwidth of these overlapping absorption and scattering
bands, and consequently the figure of merit of the nanoparticle, as
a localized SPR sensor, no longer has a constant value.