Plasmonic light scattering from nanoscopic metal tips

Linear light scattering by individual nanoscopic metal wire tips is investigated. Using evanescent-wave excitation, the spectral and polarization dependence of the emission are addressed. Choosing gold and tungsten as representative tip materials, intense scattering and a strongly plasmon-resonant behavior observed for gold contrasts a comparatively weak and spectrally flat response for tungsten. Spectral dependence and local-field enhancement are found to be sensitive to details of the structural parameters and can be described by a simple model. The results provide selection criteria for tips to be used in scattering-type near-field microscopy or photoemission in inelastic tunneling spectroscopy.This revised version was published online in April 2005. The last name of the corresponding author M. B. Raschke was corrected.