Surface plasmon modes of a single silver nanorod: an electron energy   loss study
  We present an electron energy loss study using energy filtered TEM of spatially resolved surface plasmon excitations on a silver nanorod of aspect ratio 14.2 resting on a 30 nm thick silicon nitride membrane. Our results show that the excitation is quantized as resonant modes whose intensity maxima vary along the nanorod's length and whose wavelength becomes compressed towards the ends of the nanorod. Theoretical calculations modelling the surface plasmon response of the silver nanorod-silicon nitride system show the importance of including retardation and substrate effects in order to describe accurately the energy dispersion of the resonant modes. 
Olivia Nicoletti, Martijn Wubs, N. Asger Mortensen, Wilfried Sigle,   Peter A. van Aken, Paul A. Midgley
physics.optics cond-mat.mes-hall