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O: Fachverband Oberflächenphysik

O 80: Poster: Scanning Probe Techniques - Method Development

O 80.8: Poster

Mittwoch, 14. März 2018, 18:15–20:30, Poster A

STM with fibre tips : A new approach to probe the local optical response of surfaces — •René Jakob and Niklas Nilius — Institute of Physics, Carl von Ossietzky University, 26111 Oldenburg, Germany

STM is an ideal tool to measure topographic and electronic properties of surfaces at atomic length scales. STM luminesce spectroscopy, which uses the inelastic tunnelling current to stimulate photon emission, enables a local optical characterization in addition. Main drawback is the low coupling strength of electrons and photons in the tip-sample gap, yielding reasonable signal-to-noise ratios only if using plasmonic materials for tip and sample. We have attempted to overcome this difficulty by coupling laser light directly into the STM junction via an optical fibre tip. To activate also the tunnelling channel, the fibre tip is coated with layers of Cr/Ag or Cr/Au. The interaction of incident photons with the surface is measured via a CCD detector in the far-field. The approach allows us to probe the optical response of surfaces covered with molecules, metal particles or oxide colour centres with high spatial resolution.