黄曲霉素B2分子吸附在银团簇的表面增强拉曼散射机理

采用密度泛函理论（DFT）B3LYP方法,6-311G（d,p）（C,H,O）/LANL2DZ（Ag）基组,计算了黄曲霉素B₂（AFB₂）分子吸附在Ag₂团簇的表面增强拉曼散射（SERS）光谱和预共振拉曼光谱,并与实验结果比较. 结果显示：AFB₂分子在基态Ag₂团簇表面吸附时,增强因子最大达到10²,对应吡喃（pyrane）环C=O伸缩振动,主要是由AFB₂分子周围化学环境改变而引起的基态静极化率改变导致的化学增强. 不同激发波长下的AFB₂分子预共振拉曼光谱的增强强度不同：电荷转移态激发波长为1144 和544 nm时拉曼信号增强了10²倍,而选择电荷转移预共振波长432和410 nm作为入射光时,其拉曼信号增强了10⁴倍,增强机理为银团簇和黄曲霉素分子之间的电荷转移共振增强. 因此通过改变入射光波长,选择电荷转移共振激发波长,更有利于强致癌物AFB₂分子的痕量检测.

Surface-Enhanced Raman Scattering Mechanism of Aflatoxin B2 Molecule Adsorbed on Silver Cluster

The surface-enhanced Raman scattering (SERS) spectrum and pre-resonance Raman spectra of Aflatoxin B₂ (AFB₂) adsorbed on silver cluster were calculated by density functional theory (DFT) methods with the B3LYP/6-311G (d,p)(C, H, O)/LanL2DZ(Ag) basis set. The results show that the SERS enhancement factors were 10², and this belongs to the C=O stretching vibration of the pyrane ring because of the larger static polarizability of the complex. The pre-resonance Raman spectra of the AFB₂-Ag₂ complex were explored at 1144 and 544 nm, which corresponds to charge transfer excitation energy, and its enhancement factor was 10². The pre-resonance enhancement factor was 10⁴ when incident light charge transfer pre-resonant wavelengths of 432 and 410 nm were selected. These come from a charge transfer resonance enhancement between the silver cluster and the AFB₂ molecule. Therefore, changing the wavelength of the incident light is more conducive to the trace detection of the strong carcinogen AFB₂.