AVS 49th International Symposium
    Nanometer Structures Tuesday Sessions
       Session NS-TuP

Paper NS-TuP7
In situ STM Study on Electrochemical Formation and Desorption of Self-assembled Monolayer in Ethanol Solution Containing KOH and Alkylthiol

Tuesday, November 5, 2002, 5:30 pm, Room Exhibit Hall B2

Session: Nanometer Structures A
Presenter: K. Uosaki, Hokkaido University, Japan
Authors: K. Uosaki, Hokkaido University, Japan
H. Wano, Hokkaido University, Japan
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Oxidative formation and reductive desorption of self-assembled monolayer (SAM) of alkylthiol in ethanol solution containing KOH and various concentration of alkylthiol was investigated by in situ STM. Cyclic voltammograms show the formation process is slower than the desorption process. When the concentration of the thiol was very low (~ micro M), no vacancy island (VI) was observed even in positive potential region where SAM formation is expected. As more thiol was added at the positive potential region, the growth of VIs, i.e., SAM, was observed. The VIs disappeared and herringbone structure appeared on the surface as potential became more negative than the certain value, showing the restoration of the reconstructed, i.e., clean, surface. The herringbone structure became clearer with time. When the potential was scanned positively, disappearance of the herringbone structure and the growth of the VIs were observed. Drastic change of step lines reflecting the higher mobility of gold atoms was also observed during the formation and desorption of the SAM.