金与银电极表面甘氨酸分子吸附作用的SERS光谱研究

SERS study with adsorption of glycine molecules modified on gold or silver electrode surface

本文利用表面增强拉曼光谱(SERS)技术研究了甘氨酸在金与银基底表面的吸附作用特征。研究表明甘氨酸分子以COO-的不对称形式吸附于金电极表面,且NH2也是其可能的吸附位点;而在银电极表面,则主要是通过COO-的对称形式而吸附。在此基础上,进一步研究了电极电位与溶液酸碱性对吸附于粗糙化银电极表面甘氨酸分子吸附作用的影响。研究结果表明,甘氨酸分子中去质子化羧基的吸附作用受电位影响较小,而电位对-NH3+吸附作用的影响程度较大。另一方面,溶液pH值对银电极表面的甘氨酸分子吸附行为的影响也较为显著。随着溶液酸性减小羧基倾向于相对于电极表面平行吸附。这是由于随着溶液碱性增大氨基质子化程度的减小,有利于氨基在银电极表面吸附。这将改变分子的吸附构型使其更接近于电极表面。这些变化主要出现在pH值大于10的条件下。

In this paper,surface enhanced Raman scattering（SERS）technique was used to obtain the information about adsorption configurations of glycine molecules modified on roughened gold or silver electrode surface.The results obtained here reveal that the adsorption configuration of glycine molecules mainly features the asymmetric adsorption of COO-groups on gold and the symmetric adsorption of COO-groups on silver.Furthermore,the SERS spectroscopic technique was used to investigate the impacts of electrode potential as well as solution pH on molecular adsorption of glycine modified on roughened silver electrode surface.It reveals that the impact of electrode potential on the adsorption of COO-groups is small.On the other hand,adsorption of glycine molecules modified on silver is affected by solution pH obviously.The SERS spectra show that with increasing of solution pH,the orientation of COO-groups with respect to the substrate surface tends towards planar chemisorptions.