Tuning the plasmon band number of aluminum nanorod within the ultraviolet-visible region by gold coating

The localized surface plasmon (LSP) properties of Al nanorod with Au coating have been investigated by using the quasi-static calculation. Because of the anisotropic plasmon splitting and the plasmon coupling between the Al and Au surfaces, the band number of LSP in the Al-Au core-shell nanorod could be tuned from 2 to 4 continuously in the ultraviolet-visible region. Due to the non-spherical symmetry and the dielectric polarization-induced plasmon energy fading, the Au coating-dependent plasmon shift and split are further affected by the aspect ratio and the dielectric surrounding. When the aspect ratio or the surrounding dielectric constant has a small value, the band number of LSP could only be tuned from 2 to 3. However, the band number of LSP could only be tuned from 3 to 4 when the aspect ratio or the surrounding dielectric constant has a large value. This tunable band number of LSP in the Au-coated Al nanorod provides potential application for multichannel plasmonic nanosensors.