Characteristic optical properties and synthesis of gold-silica core-shell colloids

This paper describes the synthesis of a gold-silica core-shell colloid that could be a building block for optical instruments such as photonic crystals and plasmonic waveguides. It was possible to directly coat gold nanoparticles with uniform shells of amorphous silica via a simplified process that did not use a silane coupling agent. The thickness of the silica shells could be varied from tens to several hundred nanometers by controlling the precipitation time and concentration of tetraethoxysilane