Surface-enhanced electric intensities on transition- and noble-metal spheroids

The electromagnetic intensity is known to be greatly enhanced at the surface of small Ag particles and to be less enhanced for larger Ag particles. Electrodynamic results show that the enhancement for other large metal particles (Au, Pt, Ni, Pd, Rh, and Ir) can be comparable with that for large Ag particles. Specifically, the calculated enhancement for Ag and Au prolate spheroids with a:b = 2 confirms earlier experimental results that show similar enhancements in spite of large differences in the Im ∊(ω). Results for catalytic metals in air and water show that significant enhancements can exist. These electrodynamic results indicate that surface-enhanced Raman scattering should be an effective approach for in situ monitoring of catalytic reactions at the surface of appropriately shaped metallic particles.