飞秒极紫外光场下光电子角分布研究

The character of atomic spatial scale and inherent temporal scale of coherent femtosecond X-ray and extreme ultraviolet light source plays an important role in observing and manipulating atoms, molecules and solid matters, which is of great significance for understanding and controlling light-matter interaction. Among a variety of methods for generating ultrafast XUV light source, high-order harmonic generation (HHG) can provide a table-top tunable coherent light source with a high repetition rate (kHz or MHz), high spatial coherence and femtosecond or even attosecond pulse characteristics, which is available and necessary for detecting electronic quantum state and ultrafast dynamic evolution. The interaction between an intense ultrashort pulsed laser with gaseous atoms or molecules can result in HHG, which generally is a sequence of peaks corresponding to the odd harmonics of the fundamental laser wavelength with an intensity distribution characterized by a plateau. In this project, we will build an experimental setup to investigate ultrafast electronic and structural dynamics in a variety of systems at an energy range and temporal resolution, previously unattainable before. The setup will access a new level on femtosecond or attosecond scale in study atomic and molecular processes. By matching electrical structure in atoms and molecules with XUV light, the pump-probe technique applied with IR pulses will fulfill the measurement of ultrafast dynamics. Compared with other light source, femtosecond XUV pulses will simply the interaction and purified the experimental results. In this study, we build and apply a tunable ultrafast extreme ultraviolet coherent light source based on HHG driving by intense femtosecond laser with Velocity map imaging technique to investigate photoelectron distributions, which is special and obtainable for realizing atomic and molecular dynamics. Evolution of quantum states will be extracted and precisely controlled through this kind of light source.

飞秒极紫外（XUV）光源具有原子级空间分辨和时间分辨的能力，对认识物质世界和控制物理过程具有重要应用。基于超快强场高次谐波产生的桌面化的XUV光源能够在以往不易达到的能量范围和时间分辨率的情况下探测物质的电子结构及动力学性质。本项目计划基于当前发展的高次谐波技术产生超快单波长可调谐极紫外相干光源，结合极紫外光源特性，欲实现飞秒量级的可调协XUV光源对原子分子动力学信息刻画的研究平台。该平台的发展成为在飞秒或阿秒时间分辨尺度上研究或操控原子或分子内电子动力学的新可能。通过结合原子分子量子态结构特征，以超短极紫外单色光源结合近红外光源实现量子态动力学信息的实验研究及演化测量。基于目前发展的桌面化飞秒极紫外光源将成为特色光场调控技术手段，结合速度成像、泵浦探测技术实现该波段的光电子角分布测量，提取量子态动力学演化信息及实现对原子分子内壳层电离过程的精确测控。