SERS Model Taking Both Chemical Enfancement and Physical Enhancement into Consideration

Taking both the coupling between the molecule and the enhancement of the local field into consideration, we deduced an expression of the enhancement factor (G) for the Surface Enhanced Raman Scattering (SERS). Tn our treatment, the surface plasmon (SP) act as an important role in adsorption. It is clear from this expression that there are two parts which contribute to the enhancement factor G. The short range one (G₁), originating mainly from charge transfer (CT) between the molecule and the metal, turns to be of 10²-10³. The long range part (G₂), originating from local-field enhancement, turns to be 10³-10⁴. The SERS activity of the molecule depends on the following facts:(1) the static dipole moment (D) of the molecule. (2) the amount of charge transfer between the molecule and the metal. (3) the electronic structure or the molecule. The SERS activity of the metal depends on:(1) the quanta of the surface plasma (\hbar \omega_s p), (2) the imaginary part of the dielectric constant of the metal. (3) the surface roughness.