对巯基苯甲酸的表面增强拉曼光谱

应用表面增强拉曼光谱研究了吸附于粗糙银电极表面的对巯基苯甲酸。对巯基苯甲酸以去质子的形式通过巯基端进行吸附，表面Ag-S键的形成及羧基的结构改变直接影响苯环的电子结构。羧基的振动谱峰均对其质子化较为敏感，其峰强度随pH值的变化表明吸附态对巯基苯甲酸的pKa约为5．9。铜离子可与吸附对巯基苯甲酸形成表面络合物，配位反应与羧基的质子化反应密切相关。

Surface-enhanced Raman Spectroscopy of 4-Mercaptobenzoic Acid

Surface enhanced Raman spectroscopy of 4 mercaptobenzoic acid was investigated on electrochemically roughened silver electrodes. 4 Mercaptobenzoic acid was adsorbed on the electrode surface via its thiol substituent, the formation of surface Ag S bond and the structural change of carboxylic acid group have large effect on the electronic structure of benzene ring. The vibrations of carboxylic acid group are sensitive to its protonation, the p K a value of the adsorbed 4 mercaptobenzoic acid was estimated ca. 5.9 from the variation of the intensities of these vibrations with the pH of solution. Copper ion can be coordinated to the adsorbed 4 mercaptobenzate to form surface complex, however, the complexation is dependent on the protonation of the carboxylate group.