Probing Multi-Electron Dynamics with Absolute Carrier-Envelope-Phase (CEP) Dependent Strong Field Interaction

摘要：原子是由数量相等的电子和原子核组成的，它们是电荷中性的。因此，它们不应该相互吸引。然而，众所周知，原子可以聚集在一起，形成生命所必需的最复杂的分子，例如蛋白质和dna。这是因为许多电子的相关运动可以把原子粘在一起。这叫做化学键。如果人们能够完全理解和控制这些运动，人们就可以解决许多实际问题，比如制造新的分子来治疗疾病。然而，由于化学键的多电子性质，这个问题非常复杂，很难解决。在这个项目中，李教授和韦恩州立大学的学生将使用一种非常强烈但控制良好的激光从原子和小分子中撕裂一两个电子，并观察它们如何与其他电子和激光相互作用。这是一种研究电子运动的新方法，将提供前所未有的知识，可能导致新的化学反应控制方法。额外的好处包括开发新的激光技术和下一代化学家和物理学家的培训。技术读者摘要：在这个项目中，多电子动力学的一个重要方面——多电子库仑势，它与离开电子的相互作用以及这种相互作用在强场电离过程中的后果——将被研究。主要的实验方法是使用高性能离子-电子重合/协方差技术与近红外激光脉冲（5 fs）相结合。本文将充分表征短周期脉冲的脉冲持续时间、带宽和相位等特性。具体来说，李教授和他的学生们的目标是开发一种新技术，首次在没有理论输入的情况下确定线极化少周期脉冲的绝对载波包络相位（CEP）。这将提供相位相关现象的独立校准。此外，将CEP的绝对依赖数据，如双电离产率、电子动量分布和解离双电离的分支比，与使用和不使用单活性电子近似（SAE）的不同理论模型的结果进行直接比较，以揭示多电子动力学在原子和小分子系统中的重要性。提出的研究利用尖端的实验能力，并将揭示复杂的多电子动力学的新信息。这项研究还将为研究强场动力学提供前所未有的工具。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。

General audience abstract:Atoms are made of equal numbers of electrons and nuclei and they are charge neutral. Therefore, they should not attract each other. However, it is well known that atoms can group together and form the most complex molecules that are indispensable for life, e. g., proteins and DNAs. The reason for this is because the correlated motions of many electrons can glue atoms together. This is called chemical bonding. If one can fully understand and control these motions, one can solve many practical problems such as making new molecules as cures for diseases. However, because the multi-electron nature of chemical bonding, the issue is very complex and challenging to tackle. In this project Professor Li and students at Wayne State University will use a very intense but well-controlled laser to rip one or two electrons from atoms and small molecules and watch how they interact with the rest of the electrons as well as the laser. This is a new way to study electronic motions and will offer unprecedented knowledge that might lead to novel control methods of chemical reactions. Additional benefit includes developing new laser technologies and training of the next generation of chemists and physicists.Technical audience abstract:In this project an important aspect of multi-electron dynamics - the multi-electron Coulomb potential, its interactions with departing electrons and the consequences of such an interaction in strong field ionization process - will be investigated. The major experimental approach is to use high performing ion-electron coincidence/covariance techniques coupled with few-cycle near infrared laser pulses (5 fs). The properties of few-cycle pulses such as pulse duration, bandwidth and phase will be fully characterized. Specifically, Professor Li and his students aim to develop a new technique to determine the absolute carrier envelope phase (CEP) of linearly polarized few-cycle pulses for the first time without theoretical input. This will provide independent calibration of phase-dependent phenomena. Furthermore, the absolute CEP dependent data such as double ionization yields, electron momentum distributions and branching ratios of dissociative double ionization will be compared directly with the results of different theoretical modeling with and without the single active electron approximation (SAE) to reveal the importance of multi-electron dynamics in atomic and small molecular systems. The proposed research leverages cutting-edge experimental capabilities and will uncover new information on complex multi-electron dynamics. The research will also provide unprecedented tools for studying strong field dynamics.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.