PLASMON-INDUCED CONDUCTANCE ENHANCEMENT IN SINGLE-MOLECULE JUNCTIONS

The capability to utilize plasmons to squeeze light into nano-scale metal gaps opens exciting possibilities to gate, control and steer the conductance properties of nano-scale and molecular junctions. Here, we were able to exploit the plasmonic field and show for the first time, that upon interaction with single molecule junction its conductivity is doubled.

Our experimental approach enables to couple light into the nanoscale metallic gap of the junctions where the plasmon induced oscillating field enhancement is calculated to be ~1000. Due to this intense field, conductance enhancement of single molecule junctions is observed, and it is explained to take place through the photoassisted process, in which fraction of the tunneling charge is brought into resonance with the molecular levels.

The results shown here are based on statistical analysis of hundreds of single molecule junctions and are obtained using the Squeezable Break Junction (SBJ) technique, a new method which enables efficient coupling of light into junctions as well as sensitive conductance measurements at the single molecule level.