Study of Omethoate by Vibrational and Surface Enhanced Raman Spectroscopy
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.