Quantum-size effects in SERS from noble-metal nanoparticles

Abstract

We study the role of a strong electron confinement on the surface-enhanced Raman scattering from molecules adsorbed on small noble-metal nanoparticles. We describe a novel enhancement mechanism, which originates from the different effect that confining potential has on s-band and d-band electrons. We demonstrate that the interplay between finite-size and screening effects in the nanoparticle surface layer leads to an enhancement of the surface plasmon local field acting on a molecule located in a close proximity to the metal surface. Our calculations, based on time-dependent local density approximation, show that the additional enhancement of the Raman signal is especially strong for small nanometer-sized nanoparticles.