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

Structure and surface-enhanced Raman spectra of glycine dimer adsorbed on surface of silver clusters

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.

Using the B3LYP/6 -31＋＋G＊＊ level of DFT theory, we have studied the structures , electronic properties and Raman spectra of glycine dimer and its compounds .The calculated results show that the strong binding position mainly happens at O -Ag bond for Gly2-Ag2 , leading the structure to be stable .The analysis of HOMO-LUMO gap also indicates that the Ag 2 cluster affects the electronic properties of Gly 2 , and rearranges the electronic structure.We compared the Raman spectra of Gly 2 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 re-sults will provide significantly theoretical reference for explaining some experiments and mechanism of surface -enhanced Raman scattering .