Near-Field Enhancement of Multipole Plasmon Resonances in Ag and Au Nanowires

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

JOURNAL OF PHYSICAL CHEMISTRY A

ACS Publications

Año: 2009 vol. 113 p. 4489 - 4497

1089-5639

In this paper, we investigate theoretically the electromagnetic field enhancement arising from excitation ofsilver and gold nanowires (NWs) of finite length, capable of sustaining surface plasmon resonances of differentmultipole order, using the Discrete Dipole Approximation (DDA). The influence of NW length on the degreeof enhancement and confinement of the electromagnetic field for each surface plasmon mode is analyzed bya 3D mapping of the near field for different planes around the NW as well by calculating its variation withdistance along two different directions, one parallel to and the other perpendicular to the NW axis, outsideof the NW. It was found that the enhancement is still significant at relative large distances from the NW end,its decay being of much longer range than that predicted by a simple dipole approximation, especially atnear-infrared wavelengths.