[Density functional theory investigations of the spectroscopic characteristics and luminescent mechanisms of dipterex and dichlorvos].

By using G09 program package, the ground-state structures, infrared spectra, NMR spectra, UV-Vis spectra as well as the excited structures and fluorescence/phosphorescence spectra of dipterex and dichlorvos were investigated systematically, and luminescence principles were analyzed with the molecular orbitals to provide the theoretical foundation for the detection of trace dipterex and dichlorvos. Our theoretical model revealed that the IR spectra of dipterex and dichlorvos bear strong absorptions at about 1107 cm(-1), which belong to the P-O stretch modes, but dipterex has strong absorption peaks involving the O-H bond; for UV-Vis spectra, dichlorvos has a strong absorption peak at 182.03 nm, but dipterex has a weak one at 192.42 nm, which are assigned to pipi* and sigmapi* transitions, respectively; the emission spectra of dichlorvos are very weak, and has double fluorescence/phosphorescence characteristics, which may be attributed to the resonance structures of dichlorvos; the fluorescence of dipterex has a unique broad peak at 1849.22 nm, corresponding to the LUMO-->HOMO transition of S1 state.