Plasmon-Induced Conductance Enhancement in Single-Molecule Junctions

The effect of surface plasmons on the conductance of single-molecule junctions is studied using a squeezable break junction setup. We show that the conductance of 2,7-diaminofluorene single-molecule junctions can be enhanced upon laser irradiation. Our experimental approach enables us to show that this enhancement is due to the plasmon-induced oscillating field within the nanoscale metal gap of the junctions. The effective plasmon field enhancement within the gap is calculated to be ∼1000. The experimental procedure presented in this work, which enables one to explore the coupling between plasmons and molecular excitations via transport measurements, could potentially become a valuable tool in the field of plexcitonics.