Nichols B, Chadwick H, Gordon S D S, Eyles C J, Hornung B, Brouard M, Alexander M H, Aoiz F J, Gijsbertsen A, Stolte S
The Department of Chemistry , University of Oxford , The Physical and Theoretical Chemistry Laboratory , South Parks Road , Oxford , OX1 3QZ , United Kingdom . Email:
Department of Chemistry and Biochemistry and Institute of Physical Science and Technology , University of Maryland , College Park , MD 20742 , USA . Email:
Chem Sci. 2015 Apr 16;6(4):2202-2210. doi: 10.1039/c4sc03842h. Epub 2015 Feb 3.
Rotationally inelastic collisions of NO(X) with Ar are investigated in unprecedented detail using state-to-state, crossed molecular beam experiments. The NO(X) molecules are selected in the = 0.5, = 0.5, state and then oriented such that either the 'N' or 'O' end of the molecule is directed towards the incoming Ar atom. Velocity map ion imaging is then used to probe the scattered NO molecules in well-defined quantum states. We show that the fully quantum state-resolved differential steric asymmetry, which quantifies how the relative efficiency for scattering off the 'O' and the 'N' ends of the molecule varies with scattering angle, is strongly affected by quantum interference. Significant changes in both integral and differential cross sections are found depending on whether collisions occur with the N or O ends of the molecule. The results are well accounted for by rigorous quantum mechanical calculations, in contrast to both classical trajectory calculations and more simplistic models that provide, at best, an incomplete picture of the dynamics.
利用态-态交叉分子束实验，以前所未有的详细程度研究了NO(X)与Ar的转动非弹性碰撞。选择处于 = 0.5， = 0.5状态的NO(X)分子，然后进行取向，使分子的“N”端或“O”端指向入射的Ar原子。然后使用速度映射离子成像来探测处于明确量子态的散射NO分子。我们表明，完全量子态分辨的微分空间不对称性量化了分子从“O”端和“N”端散射的相对效率如何随散射角变化，它受到量子干涉的强烈影响。根据碰撞发生在分子的N端还是O端，发现积分截面和微分截面都有显著变化。与经典轨迹计算和更简单的模型相比，严格的量子力学计算很好地解释了这些结果，后两者最多只能提供动力学的不完整图像。
