A Comparison of Raman Scattering, Resonance Raman Scattering, and Fluorescence from Molecules Adsorbed on Silver Island Films

The enhancement of Raman scattering (RS), resonance Raman scattering (RRS), and fluorescence from molecules adsorbed en silver-lsiand films is reported. A helrarchy of enhancements 1s found: 10 for RS, 10 for RRS, and 0.1-10 for fluorescence, depending on the quantum yield of the free molecule. Using the framework of the electromagnetic theory of surface-enhanced Raman scattering, generalized to treat molecular resonance phenomena, we develop a unified picture of the role of the surface plasmon resonances, and the surface-induced damping, ln the light scattering processes. The observed helrarchy of enhancements 1s shown to have important spectroscopic consequences.