| The photo-degradation of N-heterocyclic compounds was investigated by the combination of transient and stable technologies with quinoline and isoquinoline as the model compounds. The reactions of quinoline and isoquinoline with HO·, H· eaq-, SO4-·, Br2-·,N3· were investigated by radiolysis. The change of quinoline and isoquinoline under the radiation of UV light was studied by laser flash photolysis. Meanwhile, the degradation of quinoline and isoquinoline in water by the radiation of 185/254nm UV light was also studied with emphasis on the influence factors, reaction process and intermediate products.Pulse radiolysis indicated that both quinoline and isoquinoline could react with HO·, H·, eaq-, SO4-· very rapidly, but neither of them could react with N3·. Isoquinoline could be oxidized by Br2-· while quinoline couldn't. The respective rate constants of the reaction of quinoline and isoquinoline with HO·, H· and eaq- were determined. The respective rate constants of the reaction of quinoline and isoquinoline with eaq- were 7.1 ×109 mol-1dm3·s-1 and 3.4×109 mol-1·dm3·s-1, that with H· being 5.7×109 mol-1·dm3·s-1 and 4.5×109 mol-1·dm3·s-1. The respective rate constants of the reaction of quinoline and isoquinoline with HO· were 7.9×109 mol-1·dm3·s(-1) and 4.9×109mol-1·dm3·s-1 (at pH=3), 7.2×109mol-1·dm3·s(-1) and 5.5× 109 mol-1·dm3·s-1 (at pH=7), 4.4× 109 mol-1·dm3·s-1 and 6.6× 109mol-1·dm3·s-1 (at pH=11). The difference of the rate constants with HO·, H· eaq- between quinoline and isoquinoline were compared and the reason was analyzed. The structure of the transient product of the reaction of quinoline with HO·, H eaq- was more stable than that of quinoline, which result in that quinoline react with HO·, H eaq- more quickly than isoquinoline.Laser flash photolysis showed that both quinoline and isoquinoline could produce their excited state and ionize under the excitation of the laser pulse of 266nm. The respective ionization quantum yields of quinoline and isoquinoline were 3.4×10-4 and 1.58×10-4. The reason of the difference between their ionization quantum yields...
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