Vibrationally mediated negative differential resistance in a single molecule

A new mechanism for negative differential resistance (NDR) has been discovered and involves a single molecule in the junction of a scanning tunneling microscope. The NDR was observed at voltages corresponding to the vibrational energies of single pyrrolidine molecules on the (001) surface of copper at 9 K. This vibrationally mediated NDR contrasts with the previously known mechanisms which all involve the electronic states of the conducting media.