Direct Visualization of the Chemical Mechanism in SERRS of 4-Aminothiophenol/Metal Complexes and Metal/4-Aminothiophenol/Metal Junctions
Direct Visualization of the Chemical Mechanism in SERRS of 4-Aminothiophenol/Metal Complexes and Metal/4-Aminothiophenol/Metal Junctions
复制标题
4-氨基苯硫酚/金属配合物和金属/4-氨基苯硫酚/金属结的 SERRS 化学机理的直接可视化
DOI：
10.1002/cphc.200800596
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发表时间：
2009-02-02
期刊：
影响因子：
2.9
通讯作者：
Xu, Hongxing
中科院分区：
文献类型：
--
作者：
Sun, Mengtao;Xu, Hongxing
从理论上研究了对氨基硫酚（PATP）/金属配合物和金属/PATP/金属结的表面增强共振拉曼散射（SERRS）的化学增强机理。用电荷差密度方法研究了PATP与金属离子共振跃迁过程中的团簇内激发和电荷转移。发现SERRS谱中B（2）模的选择性增强不仅是由Albrecht的A项引起的（Frank-Condon术语），也来自Herzberg-Teller术语（Albrecht的B机制）对于金属/PATP/金属结，计算结果表明，Roman谱具有SERRS性质，非完全对称的B（2）当Au和Ag纳米颗粒分别为第一层和第二层时，在1064 nm的入射波长处，主要的增强机制是通过隧穿电荷转移（从Ag团簇到Au团簇的价间电子转移）的化学增强中的Herzberg-Teller项。当第一层和第二层反转时（即Ag和Au纳米颗粒分别是第一层和第二层），在1064 nm的入射波长处的罗马光谱是由于正常罗马散射，并且非完全对称的B（2）模式没有被强烈增强。我们的理论结果不仅支持了实验结果，而且提供了一个明确的物理解释。
We theoretically investigate the mechanism of chemical enhancement of surface-enhanced resonance Roman scattering (SERRS) of para-aminothiophenol (PATP)/metal complexes and metal/PATP/metal junctions. The method of charge difference density is used to visualize intracluster excitation and charge transfer (CT) between PATP and metal during the process of resonant electronic transitions. It is found that the selective enhancement of the b(2) mode in SERRS spectra result not only from Albrecht's A term (the Frank-Condon term), but also from the Herzberg-Teller term (Albrecht's B mechanism) via resonant CT For the metal/PATP/metal junctions, the calculated results reveal that the Roman spectrum is of SERRS nature and the nontotally symmetric b(2) mode is strongly enhanced at the incident wavelength of 1064 nm when Au and Ag nanoparticles are the first and second layer, respectively, and the dominant enhancement mechanism is the Herzberg-Teller term in chemical enhancement via tunneling charge transfer (intervalence electron transfer from the Ag cluster to the Au cluster). When the first and second layers were inverted (i.e. the Ag and Au nanoparticles are the first and second layers, respectively), the Roman spectrum at on incident wavelength of 1064 nm is due to normal Roman scattering, and the nontotally symmetric b(2) mode is not strongly enhanced. Our theoretical results not only support the experimental findings, but also provide a clear physical interpretation.