Effect of clustering on ellipsometric spectra of randomly distributed gold nanoparticles on a substrate.

We present a theoretical model for describing light scattering from randomly distributed Au nanoparticles on a substrate, including the clustering effect. By using the finite-element Green's function method and spherical harmonic basis functions, we are able to calculate the polarization-dependent reflectivity spectra of the system (modeled by randomly distributed nanoparticles coupled with clusters) efficiently and accurately. The calculated ellipsometric spectra of the system with clusters can adequately describe the experimental data for the whole frequency range.

Analytical solutions to light scattering by plasmonic nanoparticles with nearly spherical shape and nonlocal effect.

We derive analytical solutions for the scattering of electromagnetic waves by a nanoparticle with nearly spherical shape and nonlocal dielectric function by using an extended Mie scattering theory with additional boundary conditions. A perturbation method is used to treat the correction due to deviation from the spherical shape. A surface characteristic function is introduced to describe the non-spherical surface profile of the nanoparticle, and it plays an important role in our analytical formulation.