Abstract: The photoinduced electron transfer processes between zinc oxide and 9 kinds of Paraquats have been studied systematically by means of ESR. The dispersion system of ZnO-Paraquat-Micelle-benzene could give strong ESR signals after being irradiated by UV light, it means that photoinduced electron transfer processes between ZnO solid and Paraquat molecules took place without doubt, and PQ⁺⁺ were reduced to form PQ⁺ radicals. The results also show that the PQ⁺ radicals with conjugation structure might give stronger ESR signals than those without conjugation structure; Micelle could also increase the strength of ESR signals; As oxygen was present in the system, ESR signals of PQ⁺ radicals disappeared, but spin adducts[DMPO-O₂^-]^· and[DMPO-OH]^· were detected. It is sure that the photoinduced electron transfer processes between ZnO and Paraquats can be seriously obstructed by oxygen.

Key words: Zinc oxide, Photoinduced electron transfer, DMPO, Paraquat, ESR