Conductance of an Au mono atomic contact was investigated under the
electrochemical potential control. The Au contact showed three different
behaviors depending on the potential: 1 G0โ (G0โ = 2e2/h), 0.5
G0โ and not-well defined values below 1 G0โ were shown when the
potential of the contact was kept at -0.6 V (double layer potential), -1.0 V
(hydrogen evolution potential), and 0.8 V (oxide formation potential) versus
Ag/AgCl in 0.1 M Na2โSO4โ solution, respectively. These three
reversible states and their respective conductances could be fully controlled
by the electrochemical potential. These changes in the conductance values are
discussed based on the proposed structure models of hydrogen adsorbed and
oxygen incorporated on an Au mono atomic contact.Comment: 8 pages, 4 figures, to be appeared in Physical Review