Coherence of the electron dynamics during generation of high-order harmonics in molecules

强激光脉冲下分子高次谐波的产生是了解分子结构和动力学的重要诊断工具。高次谐波的产生发生在电离、新兴电子和离子的动力学以及重新组合到初始状态的序列中。如果电离步骤在离子中制备了相干波包，则可以通过将光子能量映射到电子偏移时间范围来从观察到的光谱中提取波包动力学。然而，如果离子和电子的状态是纠缠的，那么波包动力学不是完全相干的，可能是不可观察的。在汉诺威和z<e:1>里奇研究组的合作下，将研究从分子性质计算相干度的方法。目的是制定一个理论，不像以前的模型，描述高次谐波产生部分相干波包动力学的一般情况。这一理论将与苏黎世联邦理工学院现有的和计划中的实验联系起来。在这种情况下，分子轨道在电离过程中的弛豫也应加以研究。

The generation of high-order harmonics from molecules in strong laser pulses is an important diagnostic tool to gain insight into structure and dynamics of the molecules. High-order harmonic generation takes place as a sequence of ionisation, dynamics of the emerging electron and ion and recombination into the initial state. If the ionisation step prepares a coherent wavepacket in the ion, the wavepacket dynamics can be extracted from the observed spectrum by mapping the photon energies to a range of electron excursion times. If, however, the state of ion and electron is entangled, then the wavepacket dynamics is not fully coherent and possibly not observable. In cooperation of the groups in Hannover and Zürich, the calculation of the degree of coherence from molecular propoerties is to be investigated. The aim is the formulation of a theory that, unlike previous models, describes the general case of partially coherent wavepacket dynamics in high-order harmonic generation. This theory will be connected with existing and planned experiments at the ETH Zürich. In this context, the relaxation of molecular orbitals in the course of ionisation shall be investigated as well.