Wang Jing, Li Yafei, Wu Shiwei, Song Peng, Xia Lixin
Department of Chemistry, Liaoning University, Shenyang 110036, People's Republic of China.
J Phys Condens Matter. 2016 Jun 2;28(21):214002. doi: 10.1088/0953-8984/28/21/214002. Epub 2016 May 5.
The intermolecular interaction between fluorenone (FN) and silver surfaces was investigated experimentally and theoretically. The structural, electronic and optical properties of the FN-Ag complex indicate that the carbonyl group O atom in FN molecules is the adsorbed position site to attach the silver substrate through the weak bond O…Ag. The analysis of vibrational modes and Raman activity of the largely enhanced Raman peaks using two FN-Ag4-x (x = l, s) complex models reveals that only the a1 vibrational modes with C 2v symmetry are selectively enhanced, from the point view of the change of dipole moment and polarizability induced by the interaction between FN and Ag4 substrate. Furthermore, the direct visualized evidence of the surface-enhanced Raman scattering (SERS) chemical enhancement mechanism for the FN-Ag complex is presented. The results reveal that only the intermolecular charge transfer with π-π transition characterization between FN and an Ag4 cluster facilitates the resonance Raman process and is directly responsible for chemical enhancement of Raman scattering of the FN-Ag complex.
对芴酮（FN）与银表面之间的分子间相互作用进行了实验和理论研究。FN-Ag复合物的结构、电子和光学性质表明，FN分子中的羰基O原子是通过弱键O…Ag附着在银基底上的吸附位点。使用两个FN-Ag4-x（x = 1，s）复合物模型对大幅增强的拉曼峰的振动模式和拉曼活性进行分析，从FN与Ag4基底相互作用引起的偶极矩和极化率变化的角度来看，发现只有具有C2v对称性的a1振动模式被选择性增强。此外，还给出了FN-Ag复合物表面增强拉曼散射（SERS）化学增强机制的直接可视化证据。结果表明，只有FN与Ag4簇之间具有π-π跃迁特征的分子间电荷转移促进了共振拉曼过程，并直接导致了FN-Ag复合物拉曼散射的化学增强。
