Fig 5. Theoretical simulation of optical fields for SiO2@Ag NPs with different inter-particle distance.
The wavelength of incident light was at 532 nm. (a) An illustrated model for the nanostructure used for calculation. (b) An E-field distribution map around the nanostructure when the center-to-center distance of two spheres is smaller than the outer diameter of a sphere. The area depicted in red circle is the brightest area on silica shell surface. (c) The same as in (b) when the center-to-center distance of two spheres is larger than the outer diameter of a sphere. The area depicted in red circle is the brightest area on silica shell surface. The area depicted in red circle of (b) and (c) is the maximum (E/E0)2 of silica shell surface and same region of interest (d). A plot of (E/E0)2 at the brightest spot on silica shell surface versus the center-to-center distance of Ag NPs.