Fig. 2.

IET spectra of an anthracene thiol junction. Experimental (black) and computed spectra (red) of the anthracene (1) junction. Labels refer to the normal modes of the molecule computed in the absence of metal and numbered from the lowest energy vibration. Further computational details are given in ref. 13 and supporting information (SI) Tables 1 and 2. The observed normal modes belong to two groups: out-of-plane modes that favor the intercommunication between the σ and π tunneling channels and in-plane CC stretches that modulate the main π-type tunneling channel. The molecules couple to the electrode through the s orbital of the hydrogen and the p_z orbital of the carbon. However, in the first case, only if the CH bond bends out of plane can the electron follow the most favorable tunneling path across the molecule.