Density functional theory study on surface-enhanced Raman scattering of 4,4′-azopyridine on silver

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• 作者：Zhiping Zhuang ; Xiaohong Shang ; Xu Wang ; Weidong Ruan ; Bing Zhao
• 关键词：4 ; 4′ ; -Azopyridine (AZPY) ; Ag ; Surface-enhanced Raman scattering (SERS) ; Density functional theory (DFT) ; SERS spectra identification
• 刊名：Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy
• 出版年：2009
• 出版时间：June 2009
• 年：2009
• 卷：72
• 期：5
• 页码：954-958
• 全文大小：505 K

文摘

Surface-enhanced Raman scattering (SERS) of 4,4′-azopyridine (AZPY) on silver foil substrate was measured under 1064 nm excitation lines. Density-functional theory (DFT) methods were used to calculate the structure and vibrational spectra of models such as Ag–AZPY, Ag₄–AZPY and Ag₆–AZPY complexes with B3LYP/6-31++G(d,p)(C,H,N)/Lanl2dz(Ag) basis set. The Raman bands of AZPY were identified on the ground of analog computation of potential energy distribution. The calculated spectra of Ag₄–AZPY and Ag₆–AZPY models were much approximated to the experimental results than that of Ag–AZPY model. The DFT results showed that the angles between two pyridyl rings keep 0° from AZPY to Ag–AZPY, Ag₄–AZPY and Ag₆–AZPY model. The energy gaps between the HOMO and LUMO changed from 363 to 1140 nm for AZPY-Ag complexes according to the DFT results. An conclusion was conceived that chemical enhancement mechanism may play an important role in the SERS of AZPY on silver substrate.