Vibrational spectroscopy of single-molecule junctions by direct current measurements

A practical approach based on current-voltage characteristics measurements for detecting inelastic components Delta I of tunneling current flowing through a single-molecule junction was developed. Positive and negative Delta I was obtained for Au single atom contacts and single-molecule tunneling junctions, respectively, the discrepancy of which was attributed to the difference in the total effects of elastic and inelastic processes on the junction conductance. Numerically deduced Delta I spectra were found to allow single-molecule fingerprinting, thereby proving the capability of direct-current inelastic electron tunneling spectroscopy analysis as a simple technique for discriminating current-carrying single-molecules residing in an electrode gap. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4792048]