Second-harmonic Rayleigh scattering from a sphere of centrosymmetric material

We describe the electromagnetic theory of second-harmonic generation from t he surface of a sphere that is small compared to the wavelength of light. I n a leading-order expansion, the second-harmonic radiation is emitted in no nlocally excited electric dipole and locally excited electric quadrupole mo des. We analyze the problem with particular emphasis on experimental aspect s, such as the radiation pattern, polarization selection rules, determinati on of nonlinear susceptibilities, radiation efficiency, and spectral charac teristics.