甘氨酸二聚体在银团簇表面吸附的结构和表面增强拉曼光谱

利用密度泛函理论DFT-B3LYP方法和6-31++G**基组优化了甘氨酸二聚体(Gly2)的结构及其银复合物,并对它们的电子性质和拉曼振动光谱进行了理论研究.计算结果表明,复合物Gly2-Ag2中的O-Ag键表现了较强的吸附键位,致使结构上更为稳定.通过计算的HOMO-LUMO能隙研究也发现,银金属团簇影响了Gly2的电子特性,使得电子结构发生重排.我们对Gly2及其复合物的拉曼光谱特性进行了比较,并对主要振动模式进行了归属,其中一些特征峰位置发生了明显红移;由于银金属表面的诱导,致使复合物中某些特征拉曼峰被增强.这些研究对解释一些实验现象和SERS增强机理提供了理论参考.

Structure and Surface-Enhanced Raman Spectra of Glycine Dimer Adsorbed on Surface of Silver Clusters

Using the DFT-B3LYP/6-31++G** level of theory, we have systematically studied the structures, electronic properties and Raman spectra of glycine dimer and its compounds. The calculated results show that the strong binding position mainly happen at O-Ag bond for Gly2-Ag2, resulting in the structure to be stable. The analysis of HOMO-LUMO gap also indicates that the Ag2 cluster affects the electronic properties of Gly2, and rearranges the electronic structure. We compared the Raman spectra of Gly2 and Gly2-Ag2, and assigned main vibrational contributions for each peak, obviously some peaks appear more red-shifted wavelength. In addition, the Ag2 cluster enhances the Raman intensities of some vibrations because of the inducement of silver metal. These results will provide significantly theoretical reference for explaining some experiments and mechanism of surface-enhanced Raman scattering.