Momentum distributions from bichromatic ionization of atoms and molecules

原子和分子双色电离的动量分布

• 批准号: 281146884
• 负责人: Professor Dr. Manfred Lein
• 金额: --
• 依托单位: Institut für Theoretische Physik
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2015
• 资助国家: 德国
• 起止时间: 2014-12-31 至 2019-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/281146884?language=en
• 关键词: Momentum; distributions; bichromatic; ionization; atoms

The response of atoms and molecules to intense laser pulses composed of two colours is investigated theoretically. In one part of the project, both colours are linearly polarized in orthogonal directions in order to probe the ionization dynamics induced by the fundamental field with a weak second harmonic field. In the other part, we choose both colours circularly polarized and counter-rotating in order to exploit the unusual mapping from ionization times to final electron momenta in such bicircular fields. Bircircular fields have recently found remarkable attention in the area of high-harmonic generation, but the photoelectron momentum distributions remained mostly unexplored. The momentum distributions are calculated by numerical solution of the time-dependent Schrödinger equation in order to capture both the direct and the rescattering electron trajectories. Comparisons are made with the strong-field approximation. In atoms, application of bicircular fields for the study of sub-cycle ionization dynamics is envisaged analogous to the attoclock method. In molecules, we analyse the orientation dependence of quantities relevant for strong-field processes such as ionization times and the lateral width of the momentum distributions. In the rescattering electron signal from molecules in bicircular fields, we search for the signature of electron diffraction to perform ultrafast imaging of molecular structure.

从理论上研究了原子和分子对两种颜色组成的强激光脉冲的响应。在该项目的一部分中，两种颜色都在正交方向上线性偏振，以便探测具有弱二次谐波场的基本场引起的电离动力学。在另一部分中，我们选择圆偏振和反向旋转两种颜色，以便利用这种双圆场中从电离时间到最终电子动量的不寻常映射。双圆场最近在高次谐波产生领域引起了广泛关注，但光电子动量分布仍未得到探索。动量分布是通过与时间相关的薛定谔方程的数值求解来计算的，以便捕获直接电子轨迹和再散射电子轨迹。与强场近似进行比较。在原子中，设想应用双环场来研究子循环电离动力学，类似于 attoclock 方法。在分子中，我们分析与强场过程相关的量的方向依赖性，例如电离时间和动量分布的横向宽度。在双环场中分子的再散射电子信号中，我们寻找电子衍射的特征以对分子结构进行超快成像。