中文摘要：

用离子速度成像结合共振增强多光子电离技术研究了2一溴丁烷分子在264．775和264．86nm（约265nm）的光解离动力学,从获得的离子速度图像确定了光解产物Br和Br^＊碎片的速度分布和角度分布．其速度分布可以由一个窄的高斯分布拟合得到，它对应于沿着C-Br伸缩模式的直接解离，2-溴丁烷在约265nm的光解离中1^Q1←3^Q0的非绝热跃迁在Br离子碎片的产生中起到非常重要的作用，确定Br（2^P3／2）的相对量子产额为0．621．通过约265和约234nm处2-溴丁烷光解的比较发现，各向异性参数和相对量子产率随着波长增加而下降，3^Q0和1^Q1态势能面交叉几率随着波长增加而降低．

英文摘要：

The photodissociation dynamics of 2-bromobutane has been investigated at 264.77 and 264.86 nm by ion-velocity map imaging technique coupled with resonance-enhanced multi- photon ionization. The speed and angular distributions have been derived from the velocity map images of Br and Br^＊. The speed distributions of Br and Br^＊ atoms in the photodis- sociation of 2-bromobutane at -265 nm can be fitted using only one Gaussian function indicating that bromine fragments were produced via direct dissociation of C-Br bond. The contributions of the excited 3^Q0, 3Q1, and 1^Q1 states to the products （Br and Br^＊） were discussed. It is found that the nonadiabatic 1^Q1←3^Q0 transition plays an important role for Br photofragment in the dissociation of 2-C4HgBr at -265 nm. Relative quantum yield of 0.621 for Br（2P3/2） at -265 nm in the photodissociation of 2-bromobutane is derived. By comparing the photodissociation of 2-C4H9Br at -265 nm and that that at-234 nm, the anisotropy parameter β（Br） and β（Br^＊）, and relative quantum yield Ф（Br） decrease with increasing wavelength, the probability of curve crossing between 3 ^Q0 and 1^Q1 decreases with increasing laser wavelength.