NEAR FIELD OF MULTIPOLAR PLASMONS IN NOBLE METAL NANORODS

EZEQUIEL R. ENCINA; EDUARDO M. PERASSI; EDUARDO A. CORONADO

Buenos Aires

Congreso; 10th International Conference of Near-Field Optics, Nanophotonics and Related Techniques; 2008

Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires.

Long noble metal nanorods (NRs) are able to support, depending on their length, spectrally well separated multipole plasmon modes of excitation, which can be tuned from the visible to near infrared wavelengths by changing NR geometry. Recently, it has been demonstrated by SERS experiments that these plasmonic nanostructures are able to produce strong electromagnetic field enhancements when excited on resonance at a given plasmon mode.In this work we examine, by means of DDA simulations, the magnitude and the distribution pattern of the enhanced electric field near Ag and Au NRs surfaces when illuminated at the different resonance wavelengths corresponding to each plasmon mode. The effect of NR length, noble metal nature and dielectric environment on the field enhancement is also analyzed. The distribution patterns of the electric field around the NR are determined by the multipole order of each resonance mode, while the magnitude of the enhancement depends on the NR length and decreases exponentially with the distance to the NR surface with a decay constant controlled mainly by the plasmon mode order.