(a) Surface plasmon polaritons (SPPs) are evanescent propagating electromagnetic surface waves arising from the excitation of a collective oscillation of the free electrons in a thin metal film. (b) Localised surface plasmons (LSPs) are associated with excitations of oscillations in the bound electrons of a metallic nanoparticle.
Reprinted by permission from Macmillan Publishers Ltd: Juan et al., Nature Photon. 5, 349–56, copyright 2011.
Fig. 22.1 — Plasmonic response of metal nanostructures