氧化乐果的振动光谱及其表面增强拉曼散射研究

Study of Omethoate by Vibrational and Surface Enhanced Raman Spectroscopy

采用ATR-FTIR、FT-拉曼表征了氧化乐果在酸、碱、中性条件下的振动光谱,获得了氧化乐果分子较为全面的结构振动信息;以金/银核-壳粒子为基底,获得了不同浓度及其酸碱条件下氧化乐果的表面增强拉曼散射(SERS)光谱,考察了其分子在该基底表面的吸附状态及其酸碱影响,推测了氧化乐果的SERS机理;结果表明:νas(NH),νas(CH3),AmideⅠ,ν(POC),ν(PO),ν(C-S)为氧化乐果分子特征振动;中性条件下,氧化乐果浓度低于2.0×10-2mol/L已无明显SERS,酸、碱条件下,在2.0×10-10mol/L氧化乐果分子与基底的作用仍显著,尤其酸性的SERS更强;氧化乐果主要以磷酸酯结构与基底表面作用,探讨了酸碱条件下的不同水解历程对该作用的影响,为研究有机磷农药的形态变化提供了参考。

The vibrational structure of omethoate,and its changing features under different acid and base conditions were characterized by attenuated total reflection （ATR）-FTIR,FT-Raman spectroscopy,and the comprehensive information about omethoate structure vibrational characteristics was obtained. The surface enhanced Raman scattering （SERS） spectra of omethoate at different concentrations with different acid and base conditions,adsorbed on the substrate of core-shell Au/Ag nanoparticles,were also presented. The adsorption states of omethoate on the substrate′s surface and effects by the different acid,base conditions were investigated,with speculation of the SERS mechanism. From the results,νas（NH）,νas（CH3）,amide Ⅰ,ν（POC）,ν（PO） ,ν（C-S） are the characteristic peaks inner omethoate structure′s vibrations; below 2.0×10^-2 mol/L,omethoate had no obvious SERS at neutral condition,but there are still interactions between omethoate and the substrate in acidic and basic conditions even at 1.0×10^-10mol/L,especially in acidic condition. Interactions of omethoate with the substrate′s surface are mainly through its phosphate ester′s structure,to which the effects from different hydrolysis courses at acidic and basic conditions were revealed. This could be a reference for the other organophosphorus pesticides′ transform characterization in environment.