离子速度成像方法研究二溴甲烷的紫外光解动力学  

Photodissociation Dynamics Study of CH_2Br_2 in Ultraviolet Region by the Ion-Velocity Imaging Technique

作　　者：姬磊[1] 唐颖[2] 张冰[2] 

机构地区：[1]大庆石油学院化学化工院,大庆163318 [2]中国科学院武汉物理与数学研究所波谱与原子分子物理国家重点实验室,武汉430071

出　　处：《化学学报》2007年第6期501-508,共8页Acta Chimica Sinica

基　　金：国家自然科学基金(No.T022205)资助项目.

摘　　要：利用二维离子速度成像(Ion-Velocity Imaging)方法对二溴甲烷分子在234和267nm附近的光解动力学行为进行了研究.实验中得到了二溴甲烷光解产生的Br*(2P1/2)和Br(2P3/2)在不同波长下的角度和平动能分布.在平动能分布中发现两个高斯分布,推测其中主要是C—Br的快速解离,而高能宽分布则来自于CH2Br自由基的二次解离过程.通过角度分布得到了Br*与Br中来自直接解离和非绝热交叉跃迁两种来源的比例.结果表明Br*原子主要来自于B1态的直接解离,而Br则绝大部分是从B1态向A1的非绝热交叉跃迁得到,并导致了两种解离通道能量分布的差别.The photodissociation dynamics of CH2Br2 was investigated near 234 and 267 nm. A two dimensional photofragment ion-velocity imaging technique coupled with a （2d-1） resonance-enhanced mul- tiphoton （REMPI） ionization scheme was utilized to obtain the angular and translational energy distributions of the nascent Br（^2P3/2） and Br^＊（2p1/2） atoms. The translational energy distributions of Br and Br^＊ were found to consist of two components which should come from the radical channel and secondary dissociation process, respectively. By analyzing the angular distributions, the fractions of the direct and non-adiabatic dissociation in the Br and Br^＊ channels were obtained. It was suggested that Br^＊ come from the direct dissociation of BI state mostly, while Br atom be produced by non-adiabatic transition between the BI and AI states. Consequently, the phenomena of the higher internal energy distribution of Br channel than that of Br^＊ formation channel and the broader translational energy distribution of the former can be explained well.

关 键 词：二溴甲烷 光解动力学 离子速度成像 

分 类 号：O621.2[理学—有机化学]