Photodissociation Dynamics of Small Molecules: Collisionless and Collisional Processes

在化学部实验物理化学计划的这个项目中，赖斯勒将研究单分子和双分子相互作用中的基本状态到状态过程，特别是正在经历单分子分解的系统。最终目标是了解如何操纵和指导化学反应。原型分子HNCO的分解将使用顺序激发和成像技术进行研究。当解离太快而不能有效地与内部振动能量重新分配(IVR)竞争时，NCO、NH和CO产物态分布(PSD)中的特征将揭示动态偏置的存在。还提出了一些实验，目的是诱导选择性和考察几种势能面(PESS)对反应的控制。碰撞研究将扩展到涉及两条路径的系统，特别是在碰撞诱导自旋禁忌路径的情况下。将使用几种复杂的实验技术，如多共振激发和交叉脉冲分子束。来自哥廷根的莱因哈德·辛克教授将继续进行理论工作。在这个项目中，赖斯勒教授将研究分子的拉伸和弯曲运动对光引发的分子解离成碎片的最终结果的影响。这项研究中探讨的问题包括形成的产物的身份和各种形式的内能最终分配到碎片粒子中。这种化学键断裂动力学的基础研究在许多领域都有应用，例如对大气化学和燃烧过程的理解。

In this project in the Experimental Physical Chemistry Program of the Chemistry Division, Reisler will examine fundamental state-to-state processes in unimolecular and bimolecular interactions, particularly systems undergoing unimolecular decomposition. The ultimate goal is to understand how to manipulate and direct chemical reactivity. The decomposition of the prototype molecule HNCO will be examined using sequential excitation and imaging techniques. When dissociation is too rapid to compete effectively with internal vibrational energy redistribution (IVR), signatures in NCO, NH, and CO product state distributions (PSDs) will reveal the presence of dynamical biases. Experiments are also proposed which are aimed at inducing selectivity and examining control of reactivity by several kinds of potential energy surfaces (PESs). Collisional studies will be extended to systems that involve two pathways, especially where spin-forbidden pathways are induced by collisions. Several sophisticated experimental techniques will be used, such as multiple resonance excitation and crossed pulsed molecular beams. Theoretical work will continue with Prof. Reinhard Schinke from Goettingen. In this project Prof. Reisler will study the influence of the stretching and bending motions of a molecule on the final outcome of the light-initiated dissociation of the molecule into fragments. The issues explored in this study include the identity of products formed and the final distribution of the various forms of internal energy into the fragment particles. Such fundamental examinations of the dynamics of chemical bond breaking have applications in many areas, such as an understanding of atmospheric chemistry and combustion processes.