SPP 1134: Transient structures in condensed matter investigated by ultrafast x-ray techniques

优先项目致力于用超快x射线技术研究凝聚态物质的超快结构变化。超短硬x射线脉冲的产生和表征与x射线衍射和吸收的结构变化检测和分析过程相结合。本研究旨在对发生在10fs ~ 10ps时间尺度上的相关非平衡过程及其微观机制有一个基本的认识。这样，所研究的系统的结构和功能之间的关系将得到阐明。光诱导的超快相变，例如，从固体到液相和/或不同晶体结构之间的相变，以及晶格动力学，例如，声子波包或冲击波的传播，在金属，半导体和半导体纳米结构中进行了研究。用时间分辨x射线衍射直接监测原子位置的可逆或不可逆变化。这些实验与微观结构变化的理论模拟相结合。在结晶大分子中，如生物聚合物、染色肽和蛋白质，研究（生物）化学反应的基本步骤，在无序系统中，如液相，在环境影响下的瞬态结构。研究基于激光的超短x射线脉冲紧凑源和x射线目标和光学元件的新概念是这项工作的一个重要方面，这项工作是在参与优先方案的小组密切合作下进行的。

The priority programme is devoted to ultrafast structural changes in condensed matter which are studied by ultrafast x-ray techniques. The generation and characterization of ultrashort hard x-ray pulses are being combined with detecting and analyzing processes of structural change by x-ray diffraction and absorption. This research aims at a basic understanding of the relevant nonequilibrium processes occurring on a time scale between 10 fs and 10 ps and the underlying microsopic mechanisms. In this way, relationships between structure and function of the systems investigated will be elucidated.Photoinduced ultrafast phase transitions, e.g., from the solid to the liquid phase and/or between different crystalline structures, as well as the dynamics of crystal lattices, e.g., the propagation of phonon wave packets or shock waves, are studied in metals, semiconductors, and semiconductor nanostructures. Reversible or irreversible changes of atomic position are directly monitored by time-resolved x-ray diffraction. Such experiments are combined with theoretical simulations of the microscopic structural changes. In crystallized macromolecules, i.e. biopolymers, chromopeptides and proteins, elementary steps of (bio)chemical reactions are studied, in disordered systems, e.g., the liquid phase, transient structures under the influence of the environment. Research on laser based compact sources for ultrashort x-ray pulses and new concepts for x-ray targets and optical components represents an important aspect of this work which is worked on in close collaboration of the groups participating in the priority programme.