When irradiated with light corresponding to localized surface plasmon resonance, which is dependent on the shape of the metallic nanoparticles, the nanoparticles can be fused by a strong electric field generated in a position-specific manner. In this study, the researchers utilized this technique to construct higher-order structures by linking gold nanoparticles together, aiming to extend their unique optical properties.
Until now, it has been difficult to construct higher-order structures composed of gold nanoparticles due to the low contact probability between gold nanoparticles and the limited contact direction.
In this research, by confining multiple gold nanoparticles in a submicron-sized silica capsule with a mesoporous silica shell, the researchers increased the contact probability between the nanoparticles and created a space where gold nanoparticles could contact each other from every direction. This is the first-ever report of the successful fabrication of a three-dimensional gold nanostructure.
Electron energy loss spectroscopy (EELS) mapping calculations were performed based on scanning transmission electron microscope (STEM) images of the three-dimensional gold nanostructures obtained by this method. The results revealed that different plasmon modes are generated depending on the energy of the incident electromagnetic field and that the position of hot spots varied depending on the plasmon mode of the three-dimensional structure.