J.R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, Kansas 66506, United States.
Department of Physics, University of Connecticut, Storrs, Connecticut 06269, United States.
J Phys Chem Lett. 2020 Dec 3;11(23):10205-10211. doi: 10.1021/acs.jpclett.0c02959. Epub 2020 Nov 18.
Conformational isomerism plays a crucial role in defining the physical and chemical properties and biological activity of molecules ranging from simple organic compounds to complex biopolymers. However, it is often a significant challenge to differentiate and separate these isomers experimentally as they can easily interconvert due to their low rotational energy barrier. Here, we use the momentum correlation of fragment ions produced after inner-shell photoionization to distinguish conformational isomers of 1,2-dibromoethane (CHBr). We demonstrate that the three-body breakup channel, CH + Br + Br, contains signatures of both sequential and concerted breakup, which are decoupled to distinguish the geometries of two conformational isomers and to quantify their relative abundance. The sensitivity of our method to quantify these yields is established by measuring the relative abundance change with sample temperature, which agrees well with calculations. Our study paves the way for using Coulomb explosion imaging to track subtle molecular structural changes.
构象异构在定义从简单有机化合物到复杂生物聚合物等分子的物理和化学性质以及生物活性方面起着至关重要的作用。然而，由于其低旋转能量壁垒，这些异构体很容易相互转化，因此在实验上区分和分离它们通常是一个重大挑战。在这里，我们使用内壳层光致电离后产生的碎片离子的动量关联来区分 1,2-二溴乙烷 (CHBr) 的构象异构体。我们证明了 CH + Br + Br 的三体断裂通道包含顺序和协同断裂的特征，这些特征可以解耦以区分两种构象异构体的几何形状并量化它们的相对丰度。我们通过测量与样品温度的相对丰度变化来确定定量这些产率的方法的灵敏度，这与计算结果吻合得很好。我们的研究为使用库仑爆炸成像来跟踪微妙的分子结构变化铺平了道路。
