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。 这可以削弱键，并导致分子解离成离子碎片。 研究小分子的电离和解离过程对于检验量子理论和理解辐射损伤等实际原因都很重要。 本文研究了水分子的双光电离，其中一个光子激发两个电子。 使用了一种复杂的测量方法，在这种方法中，喷射的电子和离子碎片被同时检测到，以确定它们如何共享能量以及它们彼此远离的方向。 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。 一旦理解了基本物理并将其纳入理论模型，计算就可以用来理解辐射如何与更大的分子和材料相互作用。众所周知的COLTRIMS技术将用于研究具有57 eV光子的水分子的双光电离。光电子和离子碎片的初始动量将被确定。 此外，在解离之前表征双阳离子分子状态。 数据分析方法也将能够将电子的动量投影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，体固定微分截面，实现解离分子的前所未有的知识。该奖项反映了NSF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.