Plasmonic Enhancement of Raman Scattering on Non-SERS-Active Platinum Substrates

Gap-mode plasmon excitations on non-SERS-active metal substrates are investigated theoretically and experimentally for Pt single crystalline surfaces. A huge enhancement with the order of 10 5, which is 10 3 -fold larger than the previously reported values, is experimentally achieved on Pt substrates. Since the present technique is applicable for a well-defined smooth substrate, crystal-face dependence of adsorption geometries is also presented at Pt(100) and Pt(111). These features indicate that the concept of gap-mode plasmon excitations is practically useful for studying catalytic reaction mechanism on various metal surfaces.