New strategy for ready application of surface-enhanced resonance Raman scattering/surface-enhanced Raman scattering to chemical analysis of organic films on dielectric substrates

Dropping of appropriately concentrated AgNO3 and NaBH4 solutions, as well as laser-ablated Ag sols, onto organic molecules results in the formation of aggregated Ag nanoparticles that can induce surface-enhanced Raman scattering (SERS) for the molecules. The addition of flocculating agents such as alkali halides can further increase the Raman signals. We demonstrate in this work that Raman spectra can be obtained even for 0.01 monolayers of R6G on Si simply by spreading silver nanoparticles and/or fabricating Ag nanoparticles and nanoaggregates at the gaps and vacant sites of R6G molecules. The application prospect of the present methodology is extremely high, not only because of its simplicity but also because of the fact that the observation of vibrational spectra is one of the most incisive methods for understanding the chemical and physical phenomena on a variety of surfaces.