Charge transfer through interfacial water inside an STM junction

• Published in: Electrochimica acta Vol. 50; no. 21; pp. 4230 - 4233
• Main Authors: Yoon, Jae-Seok, Bae, Sang-Eun, Yoon, Jung-Hyun, Song, Moon-Bong, Lee, Chi-Woo J.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Oxford Elsevier Ltd 01.08.2005; Elsevier
• Subjects: Charge transfer; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Interfacial water; Other topics in structure, and nonelectronic properties of surfaces and interfaces; thin films and whiskers; Physics; Pt/Ir; STM; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Pt/Ir; Au; Charge transfer; Interfacial water; STM; Scanning tunneling microscopy; Tip surface interactions; Transport processes; Pt/lr; Electrical characteristic
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2005.03.074

Charge transfer through thin layers of water between an STM tip and an Au surface has been investigated by using a scanning tunneling microscopy (STM) technique at a relative humidity of 95%. The plateau currents were found to appear at separations larger than several Å where the current decay stops. The polarity dependence of the electrochemical currents was not observed with STM junction between an Au tip and an Au surface, which was observed with STM junction between a Pt/Ir tip and an Au surface. The plateau currents at H 2O saturation were measured to be 10–20% higher than those at D 2O saturation at bias voltages above |0.4| V. The results were rationalized in terms of the electrochemical currents originating mostly from the processes of OH − (OD −) or H 2O (D 2O) on the positive surface with different conductivity between H 2O and D 2O.