Potential-induced defects in n-alkanethiol self-assembled monolayers monitored by impedance spectroscopy
Potential-induced defects in n-alkanethiol self-assembled monolayers monitored by impedance spectroscopy
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DOI：
10.1021/jp000151o
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发表时间：
2000-09-28
影响因子：
3.3
通讯作者：
Lennox, RB
中科院分区：
文献类型：
--
作者：
Boubour, E;Lennox, RB
在不存在氧化还原活性组分的情况下，用交流阻抗谱研究了烷基乙醇胺自组装膜（SAMs）在金表面的离子渗透性。CH 3（CH 2）（n）S/Au（n = 7-15）SAM表现为离子绝缘体，直到达到或超过临界电势V-c。在比V-C更阴极的电位下，自组装膜不再是离子绝缘体，并且相位角的显著变化与低频区域中的离子渗透相关联。Ve是链长依赖性的，并且在比烷基乙醇胺电解吸电位阳极性大得多的电位（相对于Ag/AgCl为-0.15至-0.35 V）下观察到。trans-SAM离子迁移的弛豫频率（4-100 Hz）可以通过将阻抗数据拟合到适当的等效电路或通过Bode相位图来计算。
The ionic permeability of alkanethiol self-assembled monolayers (SAMs) chemisorbed on gold is studied using ac impedance spectroscopy in the absence of redox active species. CH3(CH2)(n)S/Au (n = 7-15) SAMs behave as ionic insulators until a critical potential, V-c, is reached or exceeded. At potentials more cathodic than V-c, SAMs are no longer ionic insulators and a significant change in the phase angle is associated with ion penetration in the low-frequency region. Ve is chain length dependent and is observed at potentials (-0.15 to -0.35 V vs Ag/AgCl) that are considerably more anodic than the alkanethiol electrodesorption potential. The relaxation frequency of trans-SAM ion migration (4-100 Hz) can be calculated from fitting of the impedance data to an appropriate equivalent circuit or from Bode phase plots.