Berlin 2012 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 85: Plasmonics and nanooptics V
O 85.1: Vortrag
Freitag, 30. März 2012, 10:30–10:45, MA 005
Spectral near and far field characteristics of single plasmonic nanoantennas in the infrared — •F. Neubrech1, P. Alonso Gonzalez2, P. Albella3, C. Huck1, F. Casanova2, L. E. Hueso2, J. Chen2, F. Golmar2, A. Pucci1, J. Aizpurua3, and R. Hillenbrand2 — 1Kirchhoff-Institut für Physik, Heidelberg, Germany — 2CIC nanoGUNE Consolider, San Sebastian, Spain — 3Center for Materials Physics, San Sebastian, Spain
The optical properties of metal nanoparticles are dominated by plasmonic resonances, which cause a huge field enhancement in the vicinity of the nanoparticles. Such huge near-field enhancements can be exploited for SEIRA or SERS. In both techniques one pre-condition is a good match between the vibrational excitation and the plasmonic one. Instead of near-field characteristics, far-field quantities are used to characterize the tuning, since they are easier to obtain experimentally. However, the use of far-field quantities will present several problems, since there is a shift between the near and far-field peak energies. In order to demonstrate this effect experimentally we carried out microscopic infrared spectroscopy fot the far-field optical, which enables us to record far-field spectra of single antennas. Using IR scattering near-field optical microscopy near-field intensities of the same antennas were recorded at a wavelength of 9.3 microns. Comparing the near and far-field response at the given wavelength for antennas with different lengths, we observed a significant shift of the near field peak intensity to lower energies, which is in perfect agreement with FDTD simulations.