Plasmonic scanning probe tips
In this project we investigate the fundamental processes which determine the optical response of individual metal tips used for tip-enhanced and -scattering spectroscopy. Simple analytical models allow for a description of the spectral response and underlying dephasing based on the Drude dielectric response:
Studies of the intrinsic tip luminescence provide the experimental insight into the tip plasmon as well as the plasmonic coupling between the tip and a metal substrate that leads to large field-enhancement factors. In the following figure, spectra are acquired with the tip at the indicated distance from the substrate. We can clearly see an increase in the overall emission intensity accompanied by a red-shift of the resonance peak as well as a narrowing of the spectral lineshape in accordance with theory.