Coherent Control of a Binary Reaction: Mg + H2

大约三十年前，相干控制被设想为一种利用激光场来决定化学反应命运的方法。对于破坏性的单分子过程，如破碎或解离，它已经非常成功，但控制反向的双分子键形成过程仍然是一个未解决的难题。在这个项目中，我们试图首次证明一个完整的气相二元反应的相干控制。这包括新化学键的可控形成（或光缔合），中间配合物通过锥形相交的可控动力学，另一个化学键的可控裂解以及反应产物的稳定。我们考虑一个三原子反应，它提供了最简单的非平凡模型，其中所有这些步骤都可以进行检验。这项工作的实验部分将在热管中进行，使用强的、成形的近红外飞秒激光脉冲。理论上，反应将从第一性原理出发，结合从头算电子结构和分子量子动力学计算进行研究。该项目建立在我们早期的工作基础上，展示了镁二聚体的飞秒多光子结合及其相干控制，并将其推广到具有稳定反应产物的三原子系统。

About thirty years ago, coherent control was conceived as a method to determine the fate of chemical reactions using laser fields. It has been extremely successful for destructive unimolecular processessuch as fragmention or dissociation but controlling the reverse, bimolecular process of bond formation still remains an unresolved puzzle. Within this project, we seek to demonstrate for the first time the coherent control of a complete gas-phase binary reaction. This includes the controlled formation (or photoassociation) of a new chemical bond, the controlled dynamics of the intermediate complex through a conical intersection, the controlled cleavage of another chemical bond as well as the stabilization of the reaction product. We consider a triatomic reaction which provides the simplest non-trivial model in which all these steps can be examined. The experimental part of the work will be carried out in a heat pipe, using strong, shaped near-infrared femtosecond laser pulses. Theoretically, the reaction will be studied from first principles, combining ab initio electronic structure and molecular quantum dynamics calculations. The project builds on our earlier work demonstrating femtosecond multi-photonphotoassociation of magnesium dimers and its coherent control, generalizing it to a triatomic system with stable reaction products.