Influence of dielectric core and embedding medium on the local field enhancement for gold nanoshells

The dependence of the local field enhancement in gold nanoshells was investigated as a function of the core and embedding medium dielectric constant. Numerical calculations based on quasistatic theory indicated two local field factor peaks. If the core dielectric constant is a fixed value and the dielectric constant of surrounding medium is increased from 1.0 to 6.0, the shorter wavelength peak redshifts and decreases nonlinearly, whereas the longer wavelength peak redshifts, increases first and then decreases. On the contrary, if the surrounding dielectric constant is a fixed value and the core dielectric constant is increased from 1.0 to 6.0, the shorter wavelength peak redshifts and increases nonlinearly, whereas the longer wavelength peak redshifts and decreases nonlinearly. (c) 2006 American Institute of Physics.