Momentum distributions from bichromatic ionization of atoms and molecules

从理论上研究了原子和分子对双色强激光脉冲的响应。在该项目的一部分中，两种颜色在正交方向上线性偏振，以探测由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，我们选择两种颜色的圆偏振和反向旋转，以利用不寻常的映射从电离时间的最终电子动量在这样的双环领域。双圆场近年来在高次谐波产生领域引起了极大的关注，但光电子动量分布仍然是未知的。动量分布计算的数值解的时间依赖薛定谔方程，以捕捉直接和再散射电子轨迹。与强场近似的比较。在原子中，应用双环场研究亚周期电离动力学的设想类似于阿托时钟方法。在分子中，我们分析了与强场过程相关的量的取向依赖性，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，以实现分子结构的超快成像。

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.