Numerical study of surface enhanced Raman scattering (SERS) by a radial distribution of molecules covering a metal single spherical particle

We present a computational model to analyze the electromagnetic contribution to Surface Enhanced Raman Scattering (SERS) based on Lorenz-Mie scattering for a single metal spherical particle covered by a shell of molecules, immerse, all the system, in a dielectric medium. In the model, all molecules are assumed to be an electrical dipole at fixed direction: the same of the linear polarization of the exciting plane electromagnetic field. The volume occupied for the molecules is twice the volume of the particle. A constant radial of molecular density is considered. The enhancement factor, EF is defined as the ratio of the total scattered power by the system particle-molecules to the total scattered power by the same distribution of molecules in the same dielectric medium. We study the EF for particles with radii between zero and 350 nm. Three wavelengths are used: 532, 633 and 382 nm. A comparative analysis between particles of copper, aurum and silver is presented. The 459 cm ^-1 Stokes line of carbon tetrachloride is studied.