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在金属电极表面所形成的有机分子的单分子膜或薄膜对于基础研究和实际应用都有着极其重要的意义。以化学吸附形式在金电极表面所形成的半胱胺单分子膜,常常用于蛋白质等生物大分子在金属表面进行吸附的连接层,以避免这些生物大分子在金属表面直接吸附而造成的变性、失活现象的发生。本文报道了我们采用表面增强拉曼散射光谱方法研究在金电极表面吸附的半胱胺单分子膜的结构特征。研究结果表明,在金电极表面所形成的半胱胺单分子膜中,半胱胺分子主要的构型为扭转构型。在与金表面的相互作用中,由于除巯基的结合作用以外,还存在半胱胺分子中端基氨基和金表面较强的亲和性,使得以扭转构型吸附在金表面的半胱胺单分子膜相当稳定。这是金电极表面的半胱胺单分子膜结构的主要行征。当考察外加电势对此单分子膜结构的影响时,可以发现有关扭转构型的特征谱峰其相对强度随着电位负移而减小。这一结构随电位的变化关系可以通过表面电势的变化对氨基氮原子上孤对电子与金属表面间相互作用的影响来加以阐释。
The monomolecular films or films of organic molecules formed on the surface of metal electrodes are of great significance for both basic research and practical application. Chemically adsorbed cysteamine monolayers formed on the surface of gold electrodes are often used in the attachment of biomacromolecules such as proteins to the metal surface to avoid denaturation caused by direct adsorption of these biomacromolecules to the metal surface , The occurrence of inactivation phenomenon. In this paper, we reported the structural characteristics of cysteamine monolayers adsorbed on the gold electrode by surface-enhanced Raman scattering spectroscopy. The results show that in the cysteamine monolayer formed on the surface of gold electrode, the main configuration of cysteamine molecule is a twisted configuration. In interaction with the gold surface, there is also a strong affinity of the terminal amino group in the cysteamine molecule and the gold surface in addition to the mercapto binding, so that the cysteamine adsorbed on the gold surface in a twisted configuration Monolayers are fairly stable. This is the main indication of the cysteamine monolayer structure on the surface of the gold electrode. When examining the influence of applied potential on the structure of the monomolecular film, it can be found that the relative intensity of the characteristic peak of the twisted configuration decreases as the potential is negatively shifted. The change of this structure with potential can be explained by the influence of the change of the surface potential on the interaction between the lone pair of electrons on the amino nitrogen atom and the metal surface.