In Situ Raman Spectroscopy of Redox Species Confined in Self-Assembled Molecular Films

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• 作者：Nicol&aacute ; s G. Tognalli ; Alejandro Fainstein ; Carolina Vericat ; Marí ; a E. Vela ; Roberto C. Salvarezza
• 刊名：Journal of Physical Chemistry C
• 出版年：2008
• 出版时间：March 13, 2008
• 年：2008
• 卷：112
• 期：10
• 页码：3741 - 3746
• 全文大小：138K
• 年卷期：v.112,no.10(March 13, 2008)
• ISSN：1932-7455

文摘

In situ Raman spectroscopy and electrochemical experiments are used to study different methylene blue (MB)species immobilized in molecular films (sulfur, propanethiol, dodecanethiol, mercaptopropionic acid, andmercaptoundecanoic acid monolayers), self-assembled on SERS-active Au surfaces in aqueous electrolyteunder potential control. The presence of three different MB species along reduction-oxidation cycles is inferred,irrespective of the nature of the molecular film. Residual Raman intensity in the spectroscopically silentleuco methylene blue (LMB) potential range demonstrate a dissimilar degree of connectivity for electrontransfer between MB molecules and substrate depending on the spacer. In addition, the intensity of the Ramansignal depends on the monolayer chemistry where hydrophobic and/or electrostatic interactions tend to stabilizethe MB species against desorption from the molecular film driven by concentration gradients.