Surface-enhanced Raman spectroscopy (SERS): nonlocal limitations

Abstract

Giant field enhancement and field singularities are a natural consequence of the commonly employed local-response framework. We show that a more general nonlocal treatment of the plasmonic response leads to new and possibly fundamental limitations on field enhancement with important consequences for our understanding of SERS. The intrinsic length scale of the electron gas serves to smear out assumed field singularities, leaving the SERS enhancement factor finite even for geometries with infinitely sharp features. For silver nano-groove structures, mimicked by periodic arrays of half-cylinders (up to 120 nm in radius), we find no enhancement factors exceeding ten orders of magnitude (10^10).

3 pages, including 4 figures. Accepted for Opt. Lett

References in corpus (4)

• Theory of surface plasmons and surface-plasmon polaritons
• Plasmons in nearly touching metallic nanoparticles: singular response in the limit of touching dimers
• Channel plasmon-polaritons: modal shape, dispersion, and losses
• Nanostructure design for surface-enhanced Raman spectroscopy - prospects and limits

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• Nonlocal effects: relevance for the spontaneous emission rates of quantum emitters coupled to plasmonic structures
• Quantum Plasmonics: Nonlocal effects in coupled nanowire dimer