Electron Correlation Dynamics in State-Selected Triatomic Molecules Following Double Photoionization

当分子吸收高能光子时，电子可以从分子中射出。这会削弱化学键，导致分子解离成离子碎片。研究小分子中的电离和解离过程对于验证量子理论和理解辐射损伤等实际原因非常重要。本研究研究水分子的双光离，其中一个光子射出两个电子。使用了一种复杂的测量方法，在这种方法中，发射的电子和离子碎片被巧合地检测到，以确定它们是如何共享能量的，以及它们在哪个方向彼此远离。这些测量的细节将帮助理论物理学家完善吸收电离辐射的分子的量子力学模型。一旦基本物理原理被理解并纳入理论模型，计算就可以用来理解辐射如何与大分子和材料相互作用。著名的COLTRIMS技术将用于研究具有57 eV光子的水分子的双光离。光电子和离子碎片的初始动量将被确定。此外，在解离之前，将表征dication分子状态。数据分析方法还将能够将电子的动量投射到解离分子的框架中。因此，可以确定耦合光电子的状态选择，身体固定的微分截面，从而获得迄今为止前所未有的解离分子知识。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Electrons can be ejected from molecules when they absorb energetic photons. This can weaken the bonds and cause the molecule to dissociate into ionic fragments. Studying ionization and dissociation processes in small molecules is important for testing quantum theories and for practical reasons such as understanding radiation damage. This research studies double photoionization of water molecules in which a single photon ejects two electrons. A sophisticated measurement method is used in which the ejected electrons and the ionic fragments are detected in coincidence to determine how they share energy and in which direction they move away from each other. The details of those measurements will help theoretical physicists refine quantum mechanical models of molecules that absorb ionizing radiation. Once the basic physics is understood and included in the theoretical models, the calculations can be used to understand how radiation interacts with larger molecules and materials.The well-known COLTRIMS technique will be used to study double photoionization of water molecules with 57 eV photons. The initial momenta of the photoelectrons and ionic fragments will be determined. In addition, the dication molecular state will be characterized prior to dissociation. The data analysis methods will also be able to project the electrons' momenta into the frame of the dissociated molecule. As a result, state-selected, body-fixed differential cross sections for the coupled photoelectrons can be determined, achieving as-yet unprecedented knowledge of the dissociating molecule.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.