2-丁烷光解的矢量成像：通过六极态选择定向
Vectorial Imaging of the Photodissociation of 2-Bromobutane Oriented via Hexapolar State Selection
AI总结：
通过六极态选择定向2-丁烷，研究光解过程中光碎片反冲速度、跃迁电偶极矩和永久电偶极矩的矢量相关性，揭示其空间排列特征。
摘要：
分子定向技术正被用于研究基本化学过程，以突出那些被随机旋转运动掩盖的结构和动力学性质。最近，异形双极分子和手性分子的成功定向已远超以往。在本工作中，我们报告并讨论了在六极定向的2-丁烷光解实验中，光碎片反冲速度v、跃迁电偶极矩μ和永久电偶极矩d之间的相关性。通过(2+1)共振增强多光子电离技术，在234.0和254.1 nm分别获取Br* (2P1/2)和Br (2P3/2)光碎片的切片离子图像。在激光极化倾斜角45°下获得的切片离子图像详细分析提供了三个矢量的相关信息，这些矢量被两个极角α、\c{hi}和一个方位角ϕμd所限制。在254.1 nm下，从手性异构体中单独消除Br碎片得到的不对称因子接近于零；因此，光碎片的角度分布没有显著差异。在234.0 nm下消除Br*碎片主要与平行跃迁相关，导致较大的各向异性参数1.85，因此可视为单态激发。所得到的反冲框架角度被优化为α和\c{hi}分别为163.8°和164.1°，而ϕμd接近0°。由于这三个矢量仅有轻微的空间排列，两种对映体的光碎片角度分布没有显著差异。
英文摘要：
Molecular orientation techniques are becoming available in the study of elementary chemical processes, in order to highlight those structural and dynamical properties that would be concealed by random rotational motions. Recently successful orientation was achieved for asymmetric-top and chiral molecules of much larger complexity than hitherto. In this work, we report and discuss the correlation between the vectors photofragment recoil velocity v, transition dipole moment μ, and permanent dipole moment d in a dissociation experiment on hexapole oriented 2-bromobutane, photoinitiated by a linearly polarized laser. The sliced ion images of the Br* (2P1/2) and Br (2P3/2) photofragment were acquired at 234.0 and 254.1 nm, respectively, by (2+1) resonance-enhanced multiphoton ionization technique. A detailed analysis of the sliced ion images obtained at a tilting angle 45o of the laser polarization provides the information on correlation of the three vectors, which are confined by two polar angles α, \c{hi} and one azimuthal angle ϕμd in the recoil frame. The sliced ion images of Br fragments eliminated individually from the enantiomers at 254.1 nm yield the asymmetric factor close to zero; for this reason the photofragment angular distributions do not show significant differences. The elimination of Br* fragment at 234.0 nm is mainly correlated with a parallel transition, giving rise to a large anisotropy parameter of 1.85, and thus can be considered as a single state excitation. The resulting recoil frame angles are optimized to 163.8° and 164.1° for α and \c{hi}, respectively, whereas ϕμd approaches close to 0o for the best fit. Since in the present case, the three vectors have an only slight spatial arrangement, the photofragment angular distributions of the two enantiomers do not show appreciable differences...
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