The role of vibrations in single-molecule charge transport: A case study of oligoynes with pyridine anchor groups

We report on measurements on molecular wires in single-molecule junctions. The target is to identify vibrational signatures in the differential conductance spectra, which cannot be resolved for most molecular wires in the resonant transport regime. For the given molecules, we find indeed vibrational sidepeaks, which can be assigned to the longitudinal modes of the string-like central motif of the molecule by comparison with density functional theory. These data corroborate that oligoyne wires are ideally suited for characterizing vibrational sidepeaks. A current increase as a consequence of vibrational decoherence observed for thiols is, however, not found due to the pyridine anchor group chosen in the present molecules.