title: Interaction of metallic nanoparticles with dielectric substrates: effect of optical constants.
abstract: In this paper, we study the local-field enhancement in a system of a metallic nanoparticle placed very near to a dielectric substrate. In such systems, intense electric fields are localized in the gap between the particle and the substrate, creating a 'hot-spot' under appropriate excitation conditions. We use finite-element numerical simulations in order to study the field enhancement in this dielectric-metal system. More specifically, we show how the optical properties of the dielectric substrate (n and k) affect the plasmonic field enhancement in the nano-gap. We also analyze the degree of field confinement in the gap and discuss it in the context of utilization for surface-enhanced Raman scattering. We finally show the fields generated by real substrates and compare them to metallic ones.
authors.affiliation: Department of Chemistry, University of Cambridge, Cambridge, UK.
authors.forename: Tanya
authors.initials: T
authors.lastname: Hutter
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Elliott
authors.forename: Sumeet
authors.initials: S
authors.lastname: Mahajan