Bayer Tim, Wollenhaupt Matthias
Ultrafast Dynamics Group, Institut für Physik, Carl von Ossietzky Universität Oldenburg, Oldenburg, Germany.
Front Chem. 2022 Jun 2;10:899461. doi: 10.3389/fchem.2022.899461. eCollection 2022.
Atomic and molecular free electron vortices (FEVs), characterized by their spiral-shaped momentum distribution, have recently attracted a great deal of attention due to their varied shapes and their unusual topological properties. Shortly after their theoretical prediction by the single-photon ionization (SPI) of He atoms using pairs of counterrotating circularly polarized attosecond pulses, FEVs have been demonstrated experimentally by the multiphoton ionization (MPI) of alkali atoms using single-color and bichromatic circularly polarized femtosecond pulse sequences. Recently, we reported on the analysis of the experimental results employing a numerical model based on the solution of the time-dependent Schrödinger equation (TDSE) for a two-dimensional (2D) atom interacting with a polarization-shaped ultrashort laser field. Here, we apply the 2D TDSE model to study molecular FEVs created by SPI and MPI of a diatomic molecule using polarization-tailored single-color and bichromatic femtosecond pulse sequences. We investigate the influence of the coupled electron-nuclear dynamics on the vortex formation dynamics and discuss the effect of CEP- and rotational averaging on the photoelectron momentum distribution. By analyzing how the molecular structure and dynamics is imprinted in the photoelectron spirals, we explore the potential of molecular FEVs for ultrafast spectroscopy.
原子和分子自由电子涡旋（FEV），其特征在于螺旋形的动量分布，由于其多样的形状和独特的拓扑性质，最近引起了广泛关注。在用一对反向旋转的圆偏振阿秒脉冲对氦原子进行单光子电离（SPI）对其进行理论预测后不久，通过使用单色和双色圆偏振飞秒脉冲序列对碱金属原子进行多光子电离（MPI），FEV已在实验中得到证实。最近，我们报道了基于二维（2D）原子与偏振形状的超短激光场相互作用的含时薛定谔方程（TDSE）解的数值模型对实验结果的分析。在此，我们应用二维TDSE模型来研究使用偏振定制的单色和双色飞秒脉冲序列通过双原子分子的SPI和MPI产生的分子FEV。我们研究了电子 - 核耦合动力学对涡旋形成动力学的影响，并讨论了载波包相位（CEP）和旋转平均对光电子动量分布的影响。通过分析分子结构和动力学如何印刻在光电子螺旋中，我们探索了分子FEV在超快光谱学中的潜力。
