Simulation of the surrounding medium controlled local field enhancement for silver nanorods

The dependence of the local field enhancement (LFE) in silver nanorods was investigated as a function of the surrounding medium dielectric constant. Numerical calculations based on the Drude model and quasi-static theory indicated that, because of the morphological anisotropy of the silver nanorods, there are two peaks of local field factor (LFF) take place at ultraviolet and visible regions respectively. With increasing the dielectric constant of surrounding medium from 1.0 to 4.0, the shorter wavelength peak red shift linearly and increase nonlinearly, whereas the longer wavelength peak red shift nonlinearly and decrease nonlinearly. Further more, with increasing the dielectric constant of surrounding medium, the full width at half maximum (FWHM) of longer wavelength LFF peak increase obviously, whereas the FWHM of shorter wavelength peak remains unchanged ultimately.