The HeH+ isotopologues in intense asymmetric waveforms

利用定制激光场研究分子键的动力学及其对电子时间尺度的控制是QUTIF优先项目的中心课题之一。此前，氢分子离子H2+作为强场物理理论发展的模型和研究对象。毫无疑问，这种分子键具有基本的重要性，但它是一种特殊情况，因为它是完全对称的，因此是非极性的键。氢化氦离子（HeH+）作为最简单的极性分子也具有基本的相关性，它是大爆炸后宇宙中形成的第一个分子这一事实已经证明了这一点。研究它的动力学是很重要的，因为所有其他键都位于H2+和HeH+的极端情况之间。一个特别吸引人的特点是实际可用的四种质量比变化很大的同位素。另一方面，氢化氦只有作为离子才稳定。因此，它只能通过离子束装置的大量努力来研究。为了达到足够的事件率，使用了100 kHz脉冲重复率的强大激光器。通过改变载流子包络相位或使用相相干双色场在亚周期时间尺度上操纵激光场，研究解离、单电离和双电离的相位依赖性。该项目的中心目标是通过操纵光学波形来直接控制这些碎片通道。实验伴有两个互补的理论项目。由于分子的许多自由度（振动、旋转、两个电子），该理论也具有挑战性。其中一个理论项目直接基于与时间相关的Schrödinger方程，旨在尽可能准确地求解它。另一个理论项目使用蒙特卡罗模拟来计算经典轨迹。

The dynamics of molecular bonds and their control on the time scale of the electrons using tailored laser fields is one of the central topics in the Priority Program QUTIF. Previously, the hydrogen molecular ion H2+ served as a model and object of study for theory development in strong-field physics. Without doubt, this molecular bond is of fundamental importance, but it is a special case insofar as it is a perfectly symmetric and thus non-polar bond.The helium hydride ion HeH+ as the simplest polar molecule is of fundamental relevance as well, which is shown already by the fact that it is the first molecule formed in the universe after the big bang. The study of its dynamics is important because all other bonds lie between the extreme cases of H2+ and HeH+. A particularly attractive feature is the practical availability of four isotopologues with strongly varying mass ratio.On the other hand, helium hydride is stable only as an ion. Therefore, it can be studied only with the substantial effort of an ion-beam setup. To achieve sufficient event rates, a powerful laser with 100 kHz pulse repetition rate is used. The laser field is manipulated on the sub-cycle time scale by variation of the carrier-envelope phase or by using a phase-coherent two-color field, to study the phase-dependence of dissociation, single- and double ionization. The central goal of this project is direct control of these fragmentation channels relative to each other by manipulating the optical waveform.The experiments are accompanied by two complementary theory projects. Due to the many degrees of freedom of the molecule (vibration, rotation, two electrons), the theory is challenging as well. One of the theory projects is based directly on the time-dependent Schrödinger equation and aims at solving it as accurately as possible. The other theory project uses Monte-Carlo simulations for the calculation of classical trajectories.