银电极表面异亮氨酸单分子膜结构和表面性质的表面增强拉曼光谱研究

利用表面增强拉曼光谱(SERS)技术研究了在粗糙化银电极表面吸附的异亮氨酸自组装单层膜结构及其表面性质随溶液酸碱性和电极电位改变的特征.研究结果表明溶液pH值的变化并没有显著改变异亮氨酸分子在银电极表面以去质子化羧基吸附为主的特征.借助于高氯酸根离子这一SERS光谱探针,对异亮氨酸单分子膜的表面酸碱性质进行了表征和分析.而就电位改变对该单分子膜结构的影响而言,在所研究的电位范围内,单分子膜中的异亮氨酸分子是通过去质子化羧基与氨基两个位点而吸附的,且吸附作用随电位负移而呈现有规律的变化.

SERS Study of Structure and Surface Property of Self-assembled Monolayers of Isoleucine at Silver Electrode

A surface-enhanced Raman scattering (SERS) technique was used to obtain the information about the characteristics of conformation and surface property of isoleucine self-assembled monolayers (SAM). SERS spectra of isoleucine SAM modified at electrochemically roughened silver surface were obtained when solution pH value or electrode potential was changed. The results reveal that isoleucine molecules were adsorbed mainly via the deprotonated carboxyl groups at the roughened silver electrode. This feature was not changed significantly with variation of the solution pH value. The surface acid-base property of the SAM was also analyzed and characterized by means of an SERS titration method. Perchlorate ion was used as a spectroscopic probe in the SERS titration. As for the influence of the electrode potential on the SAM, it is revealed that the isoleucine molecules were adsorbed via the deprotonated carboxyl groups and amino groups within the range of electrode potential in this research. Adsorption of these isoleucine molecules on Ag surface was changed obviously with the shift of electrode potential along the negative direction.