Berlin 2024 – scientific programme
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O: Fachverband Oberflächenphysik
O 91: Scanning Probe Microscopy: Light Matter Interaction at Atomic Scales III
O 91.4: Talk
Thursday, March 21, 2024, 16:00–16:15, MA 041
Tip-enhanced Raman spectroscopy in plasmonic nanocavities: enhancement factors and applications — •Borja Cirera1, Martin Wolf2, and Takashi Kumagai3 — 1Material Science Institute of Madrid, Madrid, Spain — 2Fritz Haber Insitute, Berlin, Germany — 3Institute for Molecular Science, Okazaki, Japan
Tip Enhanced Raman Spectroscopy (TERS) in plasmonic nanocavities has reached subnanometer resolution, visualizing chemical heterogeneities and vibrations of adsorbates in the real space. The capabilities of TERS at the atomic scale are a great complement to the existing scanning probe microscopy (SPM) techniques to properly investigate the local physico-chemical properties of the adsorbates. The required Raman sensitivity generally relies on atomically-confined electromagnetic fields in (sub-)nanoscale gaps. Here, the latest results of a single C60 between a silver tip and various metallic and semiconductor substrates are presented. These model systems allow us to discuss the diverse factors contributing to the observed intensity in single molecule junctions, finding a drastic increase in the signal upon molecular point contact (MPC) formation. The resulting exceptionally chemical sensitivity is operative even for weak and non-plasmonic substrates such as Pt(111) and Si(111). These results open the possibility to probe adsorbates on catalytically relevant substrates and a wide range semiconductors, increasing the versatility of TERS beyond coinage metals. The simultaneous access to Stokes and anti-Stokes bands can also be used to investigate heating-cooling processes in non-equilibrium quantum transport systems, of great relevance in molecular electronics.
Keywords: Plasmonic nanocavity; TERS