Strong field molecular spectroscopy and dynamics

本计画是继建立并实验验证双原子分子中强共振多光子耦合理论的后续工作。 该项目的目标是利用分子氢离子中的这种现象来填充以前从未研究过的振动束缚激发态。 这一努力可能会导致在约9 eV的跃迁上产生粒子数反转。 该项目还将研究强场电离的动力学，以评估强场物理学中通常作出的一个重要假设，即最小束缚电子被强激光场电离。 很难确定哪个电子被移除，或者等价地，分子离子留在哪个电子状态。 强激光场产生的分子离子的终态将通过泵浦-探测光谱测量其独特的振动运动特征来确定。 这种振动运动还可以揭示以前没有研究过的分子的电子态信息。在特定的研究领域之外，分子系统中的强多光子耦合可能导致在真空紫外光谱区产生放大的新的和可能有效的方式，它也可能导致亚稳态氢原子的新来源。 经过多年的研究，关于双原子分子在强激光场中的行为的基本问题仍然存在，特别是振动和电子激发的程度。 在这些问题得到解答之前，诸如量子层析成像和高次谐波产生之类的应用将无法得到精确的理解。 在解决这些问题的同时，该项目将确定有关分子离子电子结构的新信息，这对物理化学很重要。 最后，这些实验需要最先进的激光系统，让学生动手经验建设和完善最新的激光和光学技术，为各种研究为基础的学术或高科技职业道路做好准备。

This project will follow up work that established and experimentally verified a theory of strong resonance multiphoton coupling in diatomic molecules. The goals of the project are to use this phenomenon in molecular hydrogen ions to populate vibrationally-bound excited states that have never before been studied. This effort will likely lead to the creation of population inversions on transitions around 9 eV. The project will also involve a study of the dynamics of strong-field ionization to evaluate an important assumption that is typically made in strong field physics, namely, the least bound electron is ionized by the strong laser field. It has been difficult to determine which electron is removed, or equivalently, in which electronic state the molecular ion is left. The final state of molecular ions produced by strong laser fields will be determined by measuring their unique vibrational motion's signature through pump-probe spectroscopy. This vibrational motion can also reveal information about electronic states of molecules that have not been studied before.Beyond the specific field of study, strong multiphoton coupling in molecular systems may lead to a novel and possibly efficient way of producing amplification in the vacuum ultraviolet spectral region and it may also lead to a new source of metastable hydrogen atoms. After many years of research, basic questions about the behavior of diatomic molecules in strong laser fields remain, especially the extent of vibrational and electronic excitation. Until these questions are answered applications such as quantum tomography and high-harmonic generation will not be precisely understood. While addressing these questions, the project will determine new information about the electronic structure of molecular ions, which is important for physical chemistry. Finally, these experiments require state-of-the-art laser systems, giving students hands on experience building and refining the latest laser and optical technologies, preparing them for a variety of research-based academic or high-tech career paths.