Cascade electric field enhancements around small nanorods of brush-shaped nanostructures

The optical properties of brush-shaped nanostructures are calculated by the discrete dipole approximation method. The results show that the E fields around the small vertical nanorods of the brush-shaped nanostructures are significantly enhanced due to the E field couplings between adjacent vertical nanorods. In addition, the heights of the large vertical nanorods dramatically affect the E field couplings and enhancements around the small vertical nanorods. These results would help to understand the large surface-enhanced Raman scattering (SERS) enhancements and the height-dependent SERS properties of nanorod array substrates prepared by the oblique angle deposition method.