Giant raman scattering cross section for an adsorbed dye at ag colloids associated with low EM field enhancement

Abstract

Surface-enhanced resonance Raman scattering (SERRS) of rhodamine 6G molecules adsorbed at aggregated Ag colloids shows an absolute cross section of σ SERRS total = 2.3 × 10 −16 cm 2, the highest value observed so far, which is nearly equal to the absorption cross section of the same dye in solution. Its magnitude as well as the weak decrease of colloidal Rayleigh scattering, but significant drop of SERRS with increasing dye coverage (0.001 < θ < 0.1), can be explained within the framework of a recently developed quantum-mechanical model of SERRS, which relates the surface enhancement, F SERRS, with the EM field enhancement, g: F SERRS≈ g 6, where g is estimated to be about 10.