The simplicity of single-molecule junctions based on direct bonding of a small molecule between two metallic electrodes make them an ideal system for the study of fundamental questions related to molecular electronics. Here we study the conductance p
roperties of six different molecules suspended between Pt electrodes. All the molecular junctions show a typical conductance of about 1G0 which is ascribed to the dominant role of the Pt contacts. However, despite the metallic-like conductivity, the individual molecular signature is well-expressed by the effect of molecular vibrations in the inelastic contribution to the conductance.
Highly conductive molecular junctions were formed by direct binding of benzene molecules between two Pt electrodes. Measurements of conductance, isotopic shift in inelastic spectroscopy and shot noise compared with calculations provide indications fo
r a stable molecular junction where the benzene molecule is preserved intact and bonded to the Pt leads via carbon atoms. The junction has a conductance comparable to that for metallic atomic junctions (around 0.1-1 Go), where the conductance and the number of transmission channels are controlled by the molecules orientation at different inter-electrode distances.
