Site Selective Inelastic Electron Tunneling Spectroscopy Probed by Isotope Labeling

We study inelastic scattering in alkanethiol self-assembled monolayers using isotope labeling and unambiguously determine which molecular vibrations are active in the inelastic electron tunneling spectroscopy. The selective deuteration of the molecule also allows us to show that the different pans of the molecule contribute approximately equally to inelastic signal. Our first principles calculations confirm the experimental results and provide insights on electron transport through molecules.