Surface plasmon resonance of gold particles adsorbed onto two-dimensional colloidal crystals

This study demonstrates the fabrication of plasmonic materials via the adsorption of Au particles approximately 100 nm in diameter onto two-dimensional (2D) colloidal crystals composed of micrometer-sized silica particles. The localized surface plasmon resonance of the Au particles was studied using reflectance spectroscopy. Employing aqueous ethylene glycol solutions featuring varying refractive indices, the resulting shifts in peak and dip wavelengths were analyzed to determine the figure of merit (FOM). Compared with that of the Au particles adsorbed on a flat glass plate, the FOM of the Au particles adsorbed on the 2D crystal increased by a factor of 3–4. This trend was also confirmed by calculations based on the coupled-dipole model. Furthermore, SPR measurements utilizing the alternating layered films of oppositely charged polymer electrolytes are presented.