Regensburg 2013 – scientific programme

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O: Fachverband Oberflächenphysik

O 8: Surface Chemical Reactions and Heterogeneous Catalysis I

O 8.9: Talk

Monday, March 11, 2013, 12:30–12:45, H33

Density Analysis of 1-Octadecanethiol (CH3 (CH2)17-SH) and 1-Hexadecanethiol (CH3 (CH2)15-SH) Self-Assembled Monolayers (SAMs) on Gold and Silver by Impedance Spectroscopy — Uddin Md. Jalal, •Nivedita Yumnam, and Veit Wagner — School of Engineering and Science, Jacobs University, Campusring 1, D-28759 Bremen, Germany

Self-assembled monolayers (SAMs) have significantly contributed to the field of interfacial electron transfer, to developing electrodes, to fabricating lipid bilayers on electrodes among others. For applications high quality self-assembled monolayers (SAMs) with low leakage currents and without pinholes are important.

In this study we measured the impedance of 1-Octadecanethiol (CH3 (CH2)17-SH) and 1-Hexadecanethiol (CH3(CH2)15-SH) based SAMs on gold (Au) and silver (Ag) surfaces prepared on polyethylene terephthalate (PET) flexible substrates to assess the quality of the SAM layers. For optimization of the quality of SAM layers on Au and Ag surfaces, the adsorption time of Octadecanethiol (CH3 (CH2)17-SH) and Hexadecanethiol (CH3 (CH2)15-SH) on gold and silver was systematically varied from 30 seconds to 24 hours. Adsorption times beyond 1 hour were found to have negligible difference in layer quality. To be able to sense leakage current for those high quality layers, low noise and low frequency measurement at 1Hz were necessary. The impedance data analyzed using an R-C model reveals that the SAMs of (CH3(CH2)15-SH) have lower leakage current in comparison to the SAMs of (CH3(CH2)17-SH).