Abstract
We have studied an indirect observation for surface plasmons on a variety of nano-structured surfaces by means of surface-enhanced Raman scattering (SERS). In this report, we find the ultrahigh Raman enhancement for carbon films on the silver dendrite structures, fabricated by electroplating. Bright spots were observed in the Raman intensity image of the sputtered carbon film on silver dendrites. In order to estimate Raman enhancement on some topographic features, (A) smooth quartz substrates without silver film, (B) smooth quartz substrates with silver film of 300 nm in thickness, (C) silver protrusions of 50 nm in the tip diameter, and (D) silver dendrites were prepared. The maximum Raman intensity of G-band and D-band for the case (D) is 88,000 times larger than that on the flat glass substrates (case(A)). The relative enhancement is 5 times for the case (B) and 400 times for the case (C). In the case (D), some strong Raman scattering points, so called “hot spots” were observed at around the region of 500 nm in the dendrite structures, where the electric field intensity can be enhanced by local plasmons.
