Dear Anish,

The obvious advantage of SERS is the enhancement of the signal, which sometimes cannot even be measured by classical Raman spectroscopy because of the low concentration of the analyte.

SERS spectra and Raman spectra are basically similar, but they are not always exactly the same. The SERS effect is highly localized ( the electrical field normal to the surface), therefore, only a signal from part of the molecule, close to the substrate, will be enhanced. When the molecule is adsorbed on the surface, its symmetry might slightly change, and so do the selection rules. Also, because plasmon resonance at the origin of the electromagnetic filed enhancement is wavelength dependent, the different spectral regions of the spectrum may be enhanced differently

Hope this will help.

Eric

SERS greatly enhances the normal Raman signal in the order of 6-8 and even it can go up to 14 orders of magnitude. forbidden signals of Raman can be appear in SERS.

Thanks Eric, it did help :)

Thanks Luis and Raju for answering.