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The extinction spectra of two-layered gold nanowires (TGNWs) have been calculated by using the vector wave function method. When the polarization direction of incident light is perpendicular to the incidence plane, it is found with increasing the incidence angle that the dipole resonance wavelength of TGNW shows a decrease, whereas the full-width at half-maximum (FWHM) for the dipole resonance peak decreases. With decreasing the shell thickness or increasing the dielectric constant of the inner core, the localized surface plasmon resonance (LSPR) of TGNW shows a distinct redshift, whereas the FWHM of the dipole peak increases. When the polarization direction of incident light is parallel to the incident plane, the LSPR in TGNW gradually appears with decreasing incidence angle and can be modulated by the geometry. We have ascribed the variations of the LSPR in TGNW to the competition between the variations of phase retardation and oscillation electrons. [ABSTRACT FROM AUTHOR]

The extinction spectra of a three-layered metal nanoshell, which consists of a particle with a dielectric core, a middle Ag (Au) layer, and an outer Au (Ag) shell, have been investigated by means of the Mie theory. With a decrease in the outer shell thickness or the middle layer thickness, the wavelengths of the localized surface plasmon resonance (LSPR) for SiO2–Ag–Au (SiO2–Au–Ag) nanoshells show distinct redshifts and the full widths at half maximum (FWHMs) for the dipole peaks in the extinction spectra decrease first and then increase. We have further investigated the influence of the embedding medium on the LSPRs for SiO2–Ag–Au and SiO2–Au–Ag nanoshells and found that the resonance wavelengths of the particles show redshift and the FWHM of the dipole peak increases with increasing the dielectric constant of the embedding medium. The calculated results indicate that the LSPR of the three-layered gold-silver nanoshells can be controlled to the near-infrared region by changing the geometry, which has practical biomedical application. [ABSTRACT FROM AUTHOR]

The influences of the anisotropic permittivity and permeability in inner core on the Fano resonance have been investigated in Ag nanoshell by means of Mie scattering theory. The decreased inner core radius can enhance the coupling between superradiant and subradiant dipole modes and hence a distinct Fano profile. With increasing the tangential permittivity or permeability of inner core, the Fano resonance shows a redshift and the magnitude of Fano profile increases. The variation of Fano resonance with anisotropic permeability of the core is much weaker than that induced by anisotropic permittivity. We further find that the combined action of the increased tangential permittivity and permeability of inner core can induce a significant enhancement of Fano resonance in Ag nanoshell., (© 2012 American Institute of Physics)