Figure 8

Electromagnetic simulations illustrating the complex spectral properties of large nanoparticle clusters. Normalized electric field plot in log scale, i.e., log(normE), in the middle plane of clusters composed of 1, 2, 3, 7, and 12 spherical 3D AuNPs (diameter 100 nm). The distance between adjacent AuNPs is between 5 and 20 nm. Inter-particle distances can be determined from the specific coordinates of the AuNPs, listed in Additional file 1: Table S2. The surrounding medium is water. Polarization of the excitation is in the horizontal direction.