Abstract
The localized plasmon resonance enhancement mechanisms were investigated as a function to increase the shell thickness of the prepared hexagonal nanodiscs arrays of Au@TiO2 core-shell. The bare Au hexagonal nanodiscs array exhibited multiple plasmon resonance modes in the ultraviolet (UV) to near-infrared (NIR) region. Au@TiO2 nanodiscs configuration present three different enhancement mechanisms with increasing TiO2 shell thickness. First, a strengthened plasmon-induced resonance energy transfer (PIRET) for higher plasmonic resonance mode in the UV region. Second, redshifted and broadened direct electron transfer (DET) processes for the plasmonic dipole resonance mode from the Vis to the NIR region. Third, an increased hybridization retardation effect for the higher plasmonic mode in the Vis region. By using a facile and cost-effective technique (nonlithographic route) to fabricate highly ordered core-shell nanodiscs arrays (Au@TiO2 hexagonal nanodiscs) on a large area of Si substrate (>cm(2)) via an ultrathin alumina membrane (UTAM), this technique provides a perfect shadow mask to fabricate Au nanodiscs arrays; furthermore, the shadow effect of UTAM pores offers enough space to cover Au nanodiscs by the TiO2. These plasmonic core-shell nanodiscs reveal a highly promising pathway to discovering new enhancement phenomena that can be applied in diverse applications such as plasmon-enhanced energy conversion, biosensing, and surface-enhanced vibrational spectroscopy.