Surface-Enhanced Raman Scattering Mechanism of Aflatoxin B-2 Molecule Adsorbed on Silver Cluster

The surface-enhanced Raman scattering (SERS) spectrum and pre-resonance Raman spectra of Aflatoxin B-2 (AFB(2)) 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 10(2), 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 AFB(2)-Ag-2 complex were explored at 1144 and 544 nm, which corresponds to charge transfer excitation energy, and its enhancement factor was 10(2). The pre-resonance enhancement factor was 10(4) 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 AFB(2) molecule. Therefore, changing the wavelength of the incident light is more conducive to the trace detection of the strong carcinogen AFB(2).