Plasmon excitation in sets of nanoscale cylinders and spheres

By means of the boundary element method, we calculate and interpret the spectral lineshapes and near field spatial distributions of sets of a few nanospheres and nanocylinders on illumination close to the plasmon polariton excitation wavelength. This collective behavior is studied versus that of one isolated particle. Comparisons with results from previous experiments are done. As far as cylinders are concerned, our procedure goes beyond former calculations based on the quasi-electrostatic approximation and, hence, it is exact. It allows to address mixtures of a few of these particles with different sizes providing the configuration possesses axial symmetry. In particular, configurations with nanoantenna behavior are discussed. Finally, we discuss in terms of the direction of propagation and polarization of the incident wave, both the spectral and spatial field distributions of a chain of three self-similar metallic nanospheres whose plasmon eigenmodes were previously analytically obtained and whose properties of nanofocusing were predicted.