基于超短脉冲诱导的高能重散射光电子研究

The study of photons and electrons irradiated by ultra-short and ultra-intense laser pulses with atoms and molecules is an important way for paving atomic and molecular structure information in high resolution. The molecular structures in sub-femtosecond and Angstrom resolution, such as orbital tomography or differential scattering cross sections, are essential understanding for chemical reaction.The tomographic reconstruction of molecular orbtial can be investigated by multi-cycle to few-cycle femtosecond laser pulses, which interact with atoms/molecules through tunelling effect based on the "three-step model" mechanism. In the project, we plan to study the imaging of the rescattering photoelectron generated by the interaction between multi to few-cycle femtosecond laser field with CEP stabilization and atom/molecule.The rescattering photoelectron will provide a direct information about differential scattering cross sections, which shows a temporal scale from femtosecond to sub-femtosecond. And also the characteristic of photoelectreon distribution, which be decided by the rescattering process, would reflect the molecular orbital structure. We can use this to construct orbitals. For different targets, the symmetry of orbitals will affect the imaging. And this way is an effective method for controlling chemcial reations in an ultrafast scale.The development for diatomic and polyatomic molecules is a crucial way for quantum control of chemical reactions.

研究原子分子与超短超强光脉冲相互作用，测量所辐射出的光子或电离出的电子是实现原子分子结构超高精度测量的最重要的技术途径。亚飞秒、埃空间尺度的分子轨道成像或微分散射截面等结构信息是深入理解化学反应本质的基础。所以基于超短脉冲诱导的"三步模型"所产生的相干辐射光场、弹性碰撞散射电子以及非弹性碰撞引起的激发或电离（如库仑爆炸）都是直接分析原子分子结构信息的重要手段。本研究计划,欲利用多周期至少周期载波包络相位稳定的飞秒激光作用于原子及分子，研究其弹性碰撞重散射光电子的分布特性。对高能重散射的光电子成像特征分析,直接体现了研究体系的微分散射截面信息,达到对电子-离子微分散射截面的直接测量。分子 轨道性质决定了重散射电子的分布。分子准直技术的应用,将使得重散射电子的干涉效应等更加突显,实现对分子轨道的精密时空测量。从简单分子到复杂分子的扩展研究为光控化学反应提供关键的量子调控基础。

超快强光场作用原子分子获得光子、电子或离子等产物，产物信息反映强场作用的物理机制。超快光场下的亚飞秒埃尺度分辨的分子轨道或者微分散射截面信息测量是本质上从原子分子层面理解化学反应的重要方面。本项目建立速度成像及结合高次谐波产生装置，实验上测量了反映电离过程中电子符合母体产物来研究散射碰撞信息。高能谐波光谱结构分析,直接体现了研究体系的分子轨道信息。针对不同双原子分子和多原子分子的研究,基于“三步模型”的高次谐波在光场参量调制下体现了双中心干涉效应，以及多轨道动力学量子干涉效应所引起的分布变化。结合分子准直技术,实现对分子轨道的精密时空测量,达到对光化学反应动力学的量子调控。