Next Generation Experiment and Theory for Photoelectron Spectroscopy

我们对分子结构和化学键性质的理解是在我们测量控制化学键的外部(价)电子特征的同时发展起来的。在这一发展中的一个关键工具是光电子光谱学，即高能脉冲光从分子中移除一个电子。通过测量出射电子的能量和它行进的方向，我们可以获得关于分子中电子和原子核排列的详细信息。化学是非常动态的，原子和分子处于不断的运动中，化学反应由结构和成键的相关变化来定义。实时测量从反应物到产物的化学动力学是具有挑战性的，需要能够解决负责化学键的价电子排列变化的探测器。使用超短光脉冲，我们可以进行具有足够时间分辨率的光电子能谱测量，以跟踪分子电子结构在反应过程中的动态变化。我们将使用新的光源和先进的理论来提供详细的光诱导化学动力学的测量和分析。这些实验将利用基于高次谐波产生的光源和高强度激光来监测所有在光化学反应中重要的结构。理论发展将把最先进的量子分子动力学模拟与高精度计算光电子光谱的新方法结合起来，使人们能够从实验数据中提取准确的图像，以实现化学反应的详细映射。这项研究将使人们能够更好地了解控制光化学反应结果的驱动力，并允许新的方法来控制、设计和指导化学反应。

Our understanding of the structure of molecules and the nature of the chemical bond has developed in tandem with our ability to measure the characteristics of the outer (valence) electrons that control chemical bonding. A key tool in this development has been photoelectron spectroscopy, whereby a high-energy burst of light removes an electron from the molecule. By measuring the energy of the outgoing electron and the direction in which it travels, we can obtain detailed information on the arrangement of the electrons and the nuclei in the molecule. Chemistry is very dynamic, with atoms and molecules in constant motion and chemical reactions defined by associated changes in structure and bonding. Measuring chemical dynamics in real time, from reactants to products, is challenging and requires probes capable of resolving the changes in the arrangement of the valence electrons responsible for chemical bonding. Using ultrashort pulses of light, we can make photoelectron spectroscopy measurements with sufficient time-resolution to track the dynamic changes in the molecular electronic structure during reactions. We will use new light sources and advanced theory to provide detailed measurements and analysis of light-induced chemical dynamics. The experiments will take advantage of high harmonic generation based light sources and high intensity lasers to monitor all of the structures important during photochemical reactions. The theory developments will combine state-of-the-art simulations of quantum molecular dynamics with new methods to calculate photoelectron spectra with high accuracy, allowing accurate images to be extracted from the experimental data to achieve a detailed mapping of the chemical reactions. This research will enable better understanding of the driving forces that control the outcomes of photochemical reactions and allow new methods to control, design, and direct chemical reactivity.