Electromagnetic aspects of the enhanced Raman scattering by a molecule adsorbed on a polarisable sphere

For a molecule placed near the surface of a polarisable sphere, the exact solutions of the Maxwell equations are given for both elastic and inelastic scatterings, which refine in several ways the electrostatic results obtained so far. Based on the solutions, the criterion for the occurrence of enhanced Raman scattering is presented and the energy balance and the image dipole effect are discussed. Also, the enhancement factors are calculated for a metallic sphere of Ag, Au and Cu using experimental data of the dielectric constants and for a model dielectric sphere with a positive dielectric constant. Among other things, the possibility of the enhanced Raman scattering due to the retardation effect involved in a dielectric sphere is emphasised.