  Quantized conductance behavior of gold nano wires was studied under
electrochemical potential control. We fabricated 1 nm long mono atomic wires in
solution at room temperature. Electrochemical potential significantly affected
the stability of the mono atomic wire and fractional conductance peak
occurrence in the conductance histogram. We revealed that the hydrogen
adsorption on gold mono atomic wires was a decisive factor of the fractional
peak, which was originated from the dynamic structural transition between two
bistable states of the mono atomic wire showing the unit and the fractional
values of the conductance. We could tune the stability of these bistable states
to make the fractional conductance state preferable.
