Gold atomic contact: Electron conduction in the presence of interfacial charge transfer

•Conductance of Au atomic contact (AC) is studied under interfacial charge transfer.•Conductance of Au AC changes from quantization to random distribution•Transient oxidation and structural relaxation of Au AC are proposed.

This paper presents a work on hitherto unreported conductance alteration of gold atomic contact by electrochemical reduction of redox species at the contact. The interfacial charge transfer current due to reduction of Ru(NH3)63 + at Au atomic contacts can cause paradigm change of electron transport through the contacts: Conductance quantization is altered to random distribution with substantially reduced length of conductance plateau on the conductance traces. Transient oxidation of the Au atomic contact upon reduction of Ru(NH3)63 +, which relaxes atomic contact structures and hence the conductance, is proposed together with DFT calculation. The observations in the present work also disclose possible mechanistic information that might be generalized to electrochemical reduction at atomic scale.