Local fields close to the surface of nanoparticles and aggregates of nanoparticles

A refined discussion of the near-field scattering of spherical nanoparticle s and the electromagnetic fields close to the particle surface is given. Ne w results for the dependence on the distance from the surface and the angul ar distribution of the scattered light in the near-field are given. It will be shown that the radial component of the electric field leads to striking differences in the phase functions in the near-field and the far-field. Ex emplary computations are presented for Ag and Au particles with different s ize. In a second part the discussion is extended to assemblies of spherical Ag and Au nanoparticles. It will be shown that large near-fields at wavele ngths commonly used in SERS experiments are obtained for aggregates. In the near-field scattering intensity "hot spots" mark regions between particles in the aggregate where the near-field is particularly high.