Contributions of r−1, r−2, r−3 terms of the full dipole fields associated with Raman scattering enhancement from CN molecules adsorbed on a 2-D array of Ag spheroids

The enhancement of Raman scattering from a CN molecule adsorbed on the tip of one of a 2-D array of Ag spheroids has been newly calculated using the full dipole fields. Results are compared to the corresponding experimental data from the lithographically produced Ag microspheroids. While the r−1 term is small in our specific configuration of molecule-spheroids arrangement, the r−2 term of the full dipole fields is found to contribute about the same amount to the excitation profile of the Raman enhancement as the conventional r−3 term. We also find a kind of spectral fluctuation in the Raman excitation profile and have demonstrated it as due to the interference between the r−2 and r−3 fields.