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大气臭氧层破坏越来越严重,卤代烷烃在太阳紫外线辐射下解离生成破坏臭氧的游离态卤素原子,是主要元凶之一.本文选用碘甲烷作为校准分子,利用离子速度成像技术和共振增强多光子电离技术测得碘甲烷在266 nm紫外光解离下产生的基态碘原子I(~2P_(3/2))在不同聚焦电压下的离子速度影像,得到离子速度成像系统的放大系数N=1.13.并利用该系统研究了1,4-氯溴丁烷在～234 nm紫外辐射下的解离动力学,分析讨论了解离产生的基态Br(~2P_(3/2))和激发态Br~*(~2P_(1/2))的速度和角度分布信息,揭示了1,4-氯溴丁烷在～234 nm紫外光解离产生基态Br原子和激发态Br~*原子的通道都是源于C-Br键排斥势能面上的快速解离.文中通过计算碎片影像角度分布的各项异性参数β值,得到了生成基态Br(~2P_(3/2))和激发态Br~*(~2P_(1/2))两个解离通道中的平行跃迁和垂直跃迁比例.另外,本文还对氯溴甲烷,1,2-氯溴乙烷,1,3-氯溴丙烷和1,4-氯溴丁烷在～234 nm下的光解动力学进行比较,分析得到双卤代烷烃分子解离机理对烷基支链长度的依赖关系.
Atmospheric ozone layer damage more and more serious, halogenated alkane in the solar ultraviolet radiation to dissociate to generate ozone-free free-state halogen atoms is one of the main culprits.This paper selects methyl iodide as a calibration molecule, the use of ion velocity imaging and resonance enhanced multiphoton ionization The ion velocity imaging of I (~ 2P_ (3/2)) ions generated by methyl iodide dissociation at 266 nm by methyl iodide under different focal voltages was measured. The amplification factor N = 1.13 of the ion velocity imaging system was obtained. The dissociation kinetics of 1,4-bromobutyl bromide at ~ 234 nm under UV radiation was studied. The ground state Br (~ 2P_ (3/2)) and excited state Br ~ * (~ 2P_ (1/2)) velocity and angle distribution information revealed that the channel of 1,4-bromobutyl bromide dissociating at ~ 234 nm UV to generate ground state Br atoms and excited state Br ~ * atoms are all sources Br-* (2P_ (3/2)) and excited state Br ~ * (3 2) were obtained by calculating the β values of the anisotropy parameters of the angular distribution of the fragment image. ~ 2P_ (1/2)) two parallel dissociation channels in the parallel transition and vertical transition ratio.In addition, this article also chloromethyl bromide , Photolysis kinetics of 1,2-chlorobromoethane, 1,3-chloropropane and 1,4-chloro-bromobutane at ~ 234 nm were compared to find out the molecular dissociation mechanism of bis-halogenated alkane to alkane The dependence of the length of the branch.