Local environment dependent linewidth of plasmon absorption in gold nanoshell: Effects of local field polarization

The linewidth of the plasmon absorption of a gold nanoshell was theoretically studied by using a Drude model and quasistatic approximation. Increasing the dielectric constant of the core or surrounding can broaden the absorption peak linearly. A mechanism based on the polarization direction of the local electric field in the gold shell was investigated to illuminate the effect of dielectric constant on the broadening of the plasmon absorption. The perpendicular local field enhances the scattering of the oscillatory electrons and brings a loss of electron phase coherence, which in turn results in a broadening of the plasmon absorption linewidth.