An electrochemical Coulomb staircase: Detection of single electron- transfer events at nanometer electrodes

Science

Volumn 277, Issue 5333, 1997, Pages 1791-1793

  Fan, Fu Ren F ^a   Bard, Allen J ^a  

^a UNIVERSITY OF TEXAS AT AUSTIN   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

CURRENT VOLTAGE CHARACTERISTICS; ELECTRON TRANSPORT PROPERTIES; ELECTRON TUNNELING; INTERFACES (MATERIALS); IONIC CONDUCTION; MOLECULES; SOLUTIONS;

COULOMB STAIRCASE; ELECTROCHEMICAL CELL; ELECTRON TRANSFER;

ELECTROCHEMICAL ELECTRODES;

ARTICLE; CELL MEMBRANE POTENTIAL; ELECTROCHEMICAL DETECTION; ELECTRODE; ELECTRON TRANSPORT; FLOW MEASUREMENT; NONHUMAN; OXIDATION REDUCTION REACTION; PRIORITY JOURNAL;

EID: 0031578438     PISSN: 00368075     EISSN: None     Source Type: Journal    
DOI: 10.1126/science.277.5333.1791     Document Type: Article

References (19)

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13. All current or voltage measurements were carried out at room temperature (25.0° ± 0.5°C) with a deaerated solution with a Keithley Model 617 electrometer. Current was found from the potential drop across the nominally 200-Tohm internal resistance at the most sensitive voltage setting. The leads were connected in the guard mode with the inner shield connected to the ungrounded electrode lead. The cell was placed inside a grounded Faraday cage.
14. 3. The very end of the tip was then exposed by applying 0.60 V versus saturated calomel electrode on the tip and -0.20 V on a conductive substrate (such as indium tin oxide, ITO) with the SECM operated in the constant current mode (with a reference current of 10 pA). As the well-insulated tip approached the surface of the substrate, the onset of an enhanced current flow caused the z-piezo to retract the tip. This process produced a hole in the tip insulation at the point of closest approach of tip to substrate while leaving most of the tip still insulated.
15. 3. The very end of the tip was then exposed by applying 0.60 V versus saturated calomel electrode on the tip and -0.20 V on a conductive substrate (such as indium tin oxide, ITO) with the SECM operated in the constant current mode (with a reference current of 10 pA). As the well-insulated tip approached the surface of the substrate, the onset of an enhanced current flow caused the z-piezo to retract the tip. This process produced a hole in the tip insulation at the point of closest approach of tip to substrate while leaving most of the tip still insulated.
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18. m.
19. Supported by the Robert A. Welch Foundation and the National Science Foundation.