XUV Frequency Combs for Precision Spectroscopy

这个项目将利用真空-紫外线(VUV)和极端紫外线(XUV)中的精确频率梳光谱来研究原子和分子跃迁，这些跃迁对增进我们对基础物理的理解具有重要价值。一种利用两个相位相干XUV飞秒频率梳的新方法将被研究为在这一难以到达的光谱区域以前所未有的精度实现高分辨率光谱的一条有希望的途径。这个项目要探索的物理将来自两个不同的目标：(1)阐明腔内高次谐波产生的物理基础如何影响XUV飞秒频率梳的转换效率和噪声特性；(2)利用双XUV频率梳方法改进分子氢中高n里德堡态(n~50-60)的测量，从而为这个物理上重要的分子系统的电离和离解能提供更好的值。该计划将为研究生提供一个独特的研究性教育，学习光-物质相互作用的基础知识，先进的激光系统，并利用它们来探测和更好地了解最基本和最常见的分子：分子氢。一些最基本的原子和分子系统在光谱的真空-紫外线部分有它们的第一次共振。这是一个几乎不存在激光光源的地区，这使得精确研究原子和分子结构变得困难，这是测试我们对当前物理模型的理解所需的。该计划将利用最近开发的源和技术来更精确地研究分子氢，并为在这一难以到达的光谱区域进行进一步研究打开大门。这些研究为培养下一代科学家为我们的国家、学术和工业研究实验室服务提供了坚实的基础。

This project will utilize precision frequency comb spectroscopy in the vacuum-ultraviolet (VUV) and extreme ultraviolet (XUV) to investigate atomic and molecular transitions that have significant value in increasing our understanding of fundamental physics. A new method utilizing two phase-coherent XUV femtosecond frequency combs will be investigated as a promising path towards high-resolution spectroscopy with unprecedented accuracy in this difficult to reach spectral region. The physics to be explored in this project will come from two distinct objectives: (1) to elucidate how the physics underlying intracavity high harmonic generation affects the conversion efficiency and noise characteristics of the XUV femtosecond frequency comb, and (2) to utilize the dual-XUV frequency comb approach to provide an improved measurement of high-n Rydberg states (n~50-60) in molecular hydrogen, thereby providing an improved value for the ionization and dissociation energy of this physically important molecular system.This program will provide a unique research-based education for graduate students in the fundamentals of light-matter interaction, advanced laser systems, and their use to probe and better understand the most basic and common molecule: molecular hydrogen. Some of the most basic atomic and molecular systems have their first resonance in the vacuum-ultraviolet portion of the light spectrum. This is a region where few laser sources exist, making it difficult to precisely study the structure of atoms and molecules needed for testing our understanding of current physical models. This program will utilize recently developed sources and techniques to study molecular hydrogen with much greater precision, and open the door to further studies in this difficult to reach spectral region. Such research provides a solid foundation to prepare the next generation of scientists to serve in our national, academic, and industrial research laboratories.