苯并咪唑类的密度泛函理论计算及拉曼光谱研究

利用激光显微拉曼光谱仪采集了三种苯并咪唑类农药(多菌灵、噻菌灵和苯菌灵)的拉曼光谱。应用密度泛函理论(DFT)中的B3LYP杂化泛函和6-31G(d, p)基组对三种苯并咪唑类农药分子进行结构优化和拉曼光谱振动频率计算。结果表明，理论计算得到的振动频率值与实验测得值吻合较好。对三种苯并咪唑类农药分子在200～3 500 cm-1范围内的振动模式进行归属，找到了苯并咪唑类分子的3个特征峰，分别位于1 015, 1 265 cm-1和1 595 cm-1附近;对比分析三种农药拉曼光谱的差异性，找到三种农药分子各自不同的特征峰。研究结果可为苯并咪唑类农药的拉曼光谱分析提供理论依据，将促进食品和农产品中苯并咪唑类农药残留的快速检测研究。

DFT and Raman Scattering Studies of Benzimidazole

The Raman spectra of carbendazim, thiabendazole and benomyl were collected by laser Raman spectrometer. The molecules of the three pesticides were optimized and calculated by B3LYP hybrid functional and 6-31G(d,p) basis set. The results showed that the calculated value anastomosed preferably to measure value. Vibrational modes of pesticide molecules were assigned between 200 and 1 600 cm-1range, and found three characteristic peaks of benzimidazole about at 1 015, 1 265 and 1 595 cm-1. The comparative analysis on the differences of normal Raman spectra, found different characteristic peaks in three pesticide molecules. The results can provide theoretical for analysis Raman spectra of benzimidazole pesticide. This work will promote the research of benzimidazole pesticide residue in food and agricultural products based on Raman spectra.