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Surface-enhanced Raman Scattering of Aflatoxin B1 on Silver by DFT Method
Si-min Gao, Hong-yan Wang*, Yue-xia Lin
School of Physical Science and Technology, Southwest Jiao tong University, Chengdu 610031, China
Abstract:
The structure, electrostatic properties, and Raman spectra of aflatoxin B1 (AFB1) and AFB1-Ag complex are studied by density functional theory with B3LYP/6-311G(d,p)/Lanl2dz basis set. The results show that the surface-enhanced Raman scattering (SERS) and pre-resonance Raman spectra of AFB1-Ag complex strongly depend on the adsorption site and the excitation wavelength of the incident light. The SERS factors are found to enhance 102-103 order compared to normal Raman spectrum of AFB1 molecule due to the larger static polarizabilities of the AFB1-Ag complex, which directly results in the stronger chemical enhancement in SERS spectra. The pre-resonance Raman spectra of AFB1-Ag complex are explored at 266, 482, 785, and 1064 nm incident light wavelength, in which the enhancement factors are about 102-104, mainly caused by the charge-transfer ex-citation resonance. The vibrational modes are analyzed to explain the relationship between the vibrational direction and the enhanced Raman intensities.
Key words:  Aflatoxin B1, Surface-enhanced Raman scattering spectrum, Pre-resonance Raman spectra, Density functional theory
FundProject:
密度泛函理论研究黄曲霉素B1的表面增强拉曼散射效应
高思敏, 王红艳*, 林月霞
西南交通大学物理科学与技术学院,成都610031
摘要:
用密度泛函理论B3LYP方法和6-311G(d,p)/Lanl2DZ优化得到黄曲霉素B1(AFB1)分子及其复合物AFB1-Ag的稳定结构,并计算了复合物的表面增强拉曼光谱和预共振拉曼光谱. 结果表明,AFB1分子的拉曼光谱很大程度依赖于吸附位点以及入射光的激发波长. 与分子的常规拉曼光谱相比,复合物表面增强拉曼光谱中C=O伸缩振动模的增强因子约为102~103复合物的极化率增强而导致的静态化学增强,并分析了振动模式的振动方向与其拉曼强度的关系.选择复合物最大吸收峰附近激发光266和482 nm以及远离共振吸收波长785和1064 nm作为入射光,计算得到不同入射光激发下复合物的预共振拉曼光谱.结果表明其增强因子最大达到104量级,主要是由电荷转移产生的共振增强引起的.
关键词:  黄曲霉素B1,密度泛函理论,表面增强拉曼散射,预共振拉曼光谱
DOI:10.1063/1674-0068/27/02/131-136
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