We present a theoretical study of the electron and nuclear dynamics that would arise in an attosecond two-color XUV-pump/XUV-probe experiment in glycine. In this scheme, the broadband pump pulse suddenly ionizes the molecule and creates an electronic wave packet that subsequently evolves under the influence of the nuclear motion until it is finally probed by the second XUV pulse. To describe the different steps of such an experiment, we have combined a multi-reference static-exchange scattering method with a trajectory surface hopping approach. We show that by changing the central frequency of the pump pulse, i.e., by engineering the initial electronic wave packet with the pump pulse, one can drive the cation dynamics into a specific fragmentation pathway. Reminiscence of this early electron dynamics can be observed in specific fragmentation channels (not all of them) as a function of the pump–probe delay and in time-resolved photoelectron spectra at specific photoelectron energies. The optimum conditions to visualize the initial electronic coherence in photoelectron and photo-ion spectra depend very much on the characteristics of the pump pulse as well as on the electronic structure of the molecule under study.

中文翻译：

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分子断裂是揭示阿秒脉冲引起的早期电子动力学的一种方式

我们介绍了在甘氨酸中一个阿秒双色XUV泵/ XUV探针实验中产生的电子和核动力学的理论研究。在此方案中，宽带泵浦脉冲突然使分子离子化，并形成一个电子波包，随后该波包在核运动的影响下演化，直到最终被第二个XUV脉冲探测到为止。为了描述这种实验的不同步骤，我们将多参考静态交换散射方法与轨迹表面跳变方法相结合。我们证明了通过改变泵浦脉冲的中心频率，即，通过用泵浦脉冲设计初始电子波包，可以将阳离子动力学驱动到特定的碎裂路径中。可以在特定的碎片化通道（不是全部碎片化通道）中观察到这种早期电子动力学的回忆，这些碎片化通道是泵浦-探针延迟的函数以及特定光电子能量下时间分辨的光电子能谱。可视化光电子和光子光谱中初始电子相干性的最佳条件在很大程度上取决于泵浦脉冲的特性以及所研究分子的电子结构。