Soft x-ray time-domain interferometry with attosecond precision: Ultrafast spectroscopy and spectro-microscopy in aqueous solutions

这是第一次，我们将在水溶液中进行桌面纳米级成像和电荷迁移研究，在X射线光谱的所谓水窗口中，这使得研究自然环境中的生物样品成为可能。时域干涉测量将允许充分利用固有的宽带水窗桌面高谐波源的可能性，使傅里叶变换光谱学具有前所未有的精度。将这种时域干涉测量与无透镜成像技术重叠关联相结合，将使纳米级光谱显微镜成为可能，即以纳米级空间分辨率和亚eV光谱分辨率测量生物样品的复杂透射率。这将使我们能够通过元素和化学对比对微米大小的生物物体的内部进行新的了解。桌面实施将促进在生物研究和医学应用中的广泛使用，例如癌细胞的分类，通过其纳米级形态识别细菌和病毒以用于定制药物，或者研究病原体与受感染细胞的相互作用以开发新的治疗策略。在水溶液中的氨基酸分子甘氨酸作为模型系统探索辐射诱导的化学反应在蛋白质和波动的水网络之间的接口的非局部松弛过程中可能发挥的作用。到目前为止，我们对辐射诱导水化学在分子尺度上的量子动力学细节的理解仍处于起步阶段。基本上，电离在液态水的辐解中产生离子和中性自由基物种的高反应性介质。高能光子驱动这种化学反应，这种化学反应在许多研究课题中发挥着重要作用，例如水冷核电站的腐蚀过程或辐射引起的生物体DNA损伤。更好地了解工作中的量子效应，而化学键在水溶液中断裂，可以支持控制，优化和工程电离辐射用于癌症治疗的放射治疗。在这里，分子内和分子间（溶质-溶剂）动力学之间的相互作用，以及电离辐射引起的电子和离子的量子水平上的电子和核动力学之间的理解是至关重要的。DFG的研究提案解决了基本的物理化学问题，例如：在水合生物分子的自由基形成和衰变过程中，超快电荷和能量再分配是如何进行的？

For the first time, we will perform table-top nanoscale imaging and charge-migration studies in aqueous solutions in the so-called water window of the x-ray spectrum, which allows to study biological samples in their natural environment. Time-domain interferometry will allow to fully exploit the possibilities of the inherently broadband water-window table-top high-harmonic sources by enabling Fourier-transform spectroscopy with unprecedented precision. Combining this time-domain interferometry with the lensless imaging technique ptychography will enable nanoscale spectro-microscopy, namely measuring the complex transmissivity of biological samples with nanoscale spatial resolution and sub-eV spectral resolution. This will allow novel insights into the interior of µm-sized biological objects with elemental- and chemical contrast. The table-top implementation will facilitate a widespread use in biological research and medical applications e.g. the classification of cancer cells, the identification of bacteria and viruses by their nanoscale morphology for customized medication or the study of the interaction of pathogens with infected cells for the development of new treatment strategies. The amino acid molecule glycine in aqueous solution serves as model system for exploring the possible role of nonlocal relaxation processes in the radiation-induced chemical reactivity at the interface between a protein and the fluctuating water network. Up to now, our understanding of the quantum dynamical details of radiation-induced water chemistry on the molecular scale is still in its infancy. Basically, ionization creates a highly reactive medium of ionic and neutral radical species in the radiolysis of liquid water. High-energy photons drive this chemical reaction, which plays an important role in many research topics, such as corrosion processes in water-cooled nuclear power plants or radiation-induced DNA damage of living organisms. Better knowledge of the quantum effects at work, while a chemical bond is broken in aqueous solution, may support controlling, optimizing, and engineering ionizing radiation to be used in radiotherapy for cancer treatment. Here, the understanding of the interplay between intra- and intermolecular (solute-solvent) dynamics, as well as between electronic and nuclear dynamics induced by ionizing radiation on the quantum level of electrons and ions is of utmost importance. The DFG research proposal addresses fundamental physico-chemical questions such as: How does ultrafast charge and energy redistribution proceed during radical formation and decay in hydrated biomolecules?