A generalized non-local optical response theory for plasmonic nanostructures.
Metallic nanostructures exhibit a multitude of optical resonances associated with localized surface plasmon excitations. Recent observations of plasmonic phenomena at the sub-nanometre to atomic scale have stimulated the development of various sophisticated theoretical approaches for their description. Here instead we present a comparatively simple semiclassical generalized non-local optical response theory that unifies quantum pressure convection effects and induced charge diffusion kinetics, with a concomitant complex-valued generalized non-local optical response parameter. Our theory explains surprisingly well both the frequency shifts and size-dependent damping in individual metallic nanoparticles as well as the observed broadening of the crossover regime from bonding-dipole plasmons to charge-transfer plasmons in metal nanoparticle dimers, thus unravelling a classical broadening mechanism that even dominates the widely anticipated short circuiting by quantum tunnelling. We anticipate that our theory can be successfully applied in plasmonics to a wide class of conducting media, including doped semiconductors and low-dimensional materials such as graphene.
1] Department of Photonics Engineering, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark [2] Center for Nanostructured Graphene (CNG), Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark.
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Mortensen
1] Department of Photonics Engineering, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark [2] Center for Electron Nanoscopy, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark.
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Raza
1] Department of Photonics Engineering, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark [2] Center for Nanostructured Graphene (CNG), Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark.
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Wubs
Department of Physics and Nanotechnology, Aalborg University, DK-9220 Aalborg, Denmark.
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Søndergaard
Department of Technology and Innovation, University of Southern Denmark, DK-5230 Odense, Denmark.
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Bozhevolnyi