Localized Surface Plasmon Resonance-Induced Welding of Gold Nanotriangles and the Local Plasmonic Properties for Multicolor Sensing and Light-Harvesting Applications

The excitation of localized surface plasmon resonance in gold nanotriangles by continuous light illumination triggered the welding of two adjacent nanotriangles into one nanoparticle. The facing localized surface plasmon resonance generated at the corners of the gold nanotriangles facilitated welding of the nanotriangles, in which electromagnetically seamless bonding was formed. We examined the scanning transmission electron microscopy–electron energy loss spectra of the obtained nanostructure and confirmed the generation of a localized plasmon mode at the bonding spot with an energy of 2.3 eV, which did not appear in the two adjacent gold nanotriangles without bonding. The experimental electron energy loss spectra and maps were supported by the simulation data calculated using the boundary element method. An electromagnetically continuous nanostructure was successfully constructed by a site-selective welding method in this work, resulting in modulation of the localized surface plasmon resonance in nanoparticles, including the localized spots, resonant wavelength, and enhancement factor. The generation of a localized surface plasmon resonance mode by welding of nanoparticles can enable multicolor sensing and light-harvesting applications.