Depolarized Hyper-Rayleigh Scattering from Copper Nanoparticles

In this paper we report the results of polarization resolved hyper-Rayleigh scattering measurements of copper nanoparticles of 5-55 nm size. The polar plot of polarization-resolved second harmonic intensity against polarization angle from the copper nanoparticles resembles the pattern seen from a dipolar source. The measured first hyperpolarizability values scale quadratically with the particle size, which implies that the second harmonic response from the copper nanoparticles results from symmetry breaking at the surface of the particle rather than in the bulk