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

我们将首次在所谓的x射线光谱的水窗口中进行桌面纳米级成像和水溶液中的电荷迁移研究，这允许在自然环境中研究生物样品。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，使傅里叶变换光谱具有前所未有的精度。将这种时域干涉测量技术与无透镜成像技术相结合，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。这将允许对微米大小的生物物体内部进行元素和化学对比的新见解。桌面实施将促进在生物学研究和医学应用中的广泛应用，例如对癌细胞进行分类，通过其纳米级形态识别细菌和病毒以定制药物，或研究病原体与受感染细胞的相互作用以制定新的治疗策略。氨基酸分子甘氨酸在水溶液中可以作为模型系统来探索非局部弛豫过程在蛋白质与波动水网络界面上辐射诱导的化学反应性中的可能作用。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，电离在液态水的辐射分解中产生了离子和中性自由基的高度反应介质。高能光子驱动这种化学反应，在许多研究课题中起着重要作用，例如水冷核电站的腐蚀过程或辐射引起的生物体DNA损伤。当化学键在水溶液中断裂时，更好地了解量子效应的作用，可能有助于控制、优化和工程电离辐射，用于癌症治疗的放射治疗。在这里，理解分子内和分子间（溶质-溶剂）动力学之间的相互作用，以及电离辐射在电子和离子的量子水平上引起的电子和核动力学之间的相互作用是至关重要的。DFG的研究计划解决了基本的物理化学问题，如：在水合生物分子的自由基形成和衰变过程中，超快电荷和能量重新分配是如何进行的？

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?