EXCITATION OF SURFACE PLASMONS IN NANOTUBES

S. SEGUI; J.L. GERVASONI; N.R. ARISTA

Algarve, Portugal

Conferencia; NANOSMAT07: International Conference on Surfaces, Coatings and Nanostructured Materials; 2007

In this work we give a brief description of the theoretical state-of-the-art regarding the excitation of plasmons in nanosystems of cylindrical symmetry. We analyze similarities and differences shown by cylindrical structures (capillaries, wires and tubes) when a charged particle excites surface and bulk plasmons on them. Recent developments are reviewed and put into perspective, with emphasis on fundamental concepts.In particular, surface plasmon excitation is studied in hollow tubules, for which we have developed expressions to evaluate the probability of excitation of the different modes for perpendicular penetrating trajectories. We make use of the equivalence between quantum and classical descriptions of the phenomenon, which allows us to evaluate in a simple manner the integrals along the tra jectory of the projectile.With this formulation, we are able to analyze resonant effects that can take place for trajectories crossing the nanostructure, in analogy with the results obtained for a reflecting trajectory on a planar surface. Due to the characteristics of the branched modes found for a tubule (corresp onding to the coupling of the inner and outer surfaces), the behaviours observed in the excitation of each branch can be explained in terms of symmetry considerations.