Electron-vibration interaction in single-molecule junctions: from   contact to tunneling regime
  Point contact spectroscopy on a H2O molecule bridging Pt electrodes reveals a clear crossover between enhancement and reduction of the conductance due to electron-vibration interaction. As single channel models predict such a crossover at transmission probability of t=0.5, we used shot noise measurements to analyze the transmission and observed at least two channels across the junction where the dominant channel has t=0.51+/-0.01 transmission probability at the crossover conductance, which is consistent with the predictions for single-channel models. 
O. Tal (1), M. Krieger (1 and 2), B. Leerink (1), and J. M. van   Ruitenbeek (1) ((1) Leiden University, The Netherlands (2)...