  We have studied the optical properties of metallic nanoparticles with
arbitrary shape. We performed theoretical calculations of the absorption,
extinction and scattering efficiencies, which can be directly compared with
experiments, using the Discrete Dipole Approximation (DDA). In this work, the
main features in the optical spectra have been investigated depending of the
geometry and size of the nanoparticles. The origin of the optical spectra are
discussed in terms of the size, shape and material properties of each
nanoparticle, showing that a nanoparticle can be distinguish by its optical
signature.
