论文标题
X射线自由电子激光器的同时明亮和深色场X射线显微镜
Simultaneous Bright- and Dark-Field X-ray Microscopy at X-ray Free Electron Lasers
论文作者
论文摘要
固体材料中的结构,应变场和缺陷分布是众多应用程序的机械和物理特性的基础。许多现代的显微镜显微镜工具表征了映射晶格扭曲或变形所需的晶粒,结构域和缺陷,但仅限于(近)表面的研究。一般而言,这样的工具不能以代表批量行为的方式探测结构动力学。基于同步加速器X射线衍射的成像长期以来一直映射了深层嵌入的结构元素,并且通过增强的分辨率,深色场X射线显微镜(DFXM)现在可以用必要的NM分辨率映射这些特征。但是,由于源和光学的限制,这些技术仍然遭受所需的集成时间。这项工作将DFXM扩展到X射线免费电子激光器,显示在这些来源可用的$ 10^{12} $光子的$ 10^{12} $光子可提供的结构表征下降至100 fs分辨率(比当前同步体图像快的数量级)。我们将XFEL DFXM设置带有同时的明亮场显微镜,以在同一体积内变化。这项工作介绍了我们以两个XFELS构建和测试的多模式超快高分辨率X射线显微镜的综合指南,并显示了初始数据,展示了两种定时策略,以研究相关的可逆或不可逆的晶格动力学。
The structures, strain fields, and defect distributions in solid materials underlie the mechanical and physical properties across numerous applications. Many modern microstructural microscopy tools characterize crystal grains, domains and defects required to map lattice distortions or deformation, but are limited to studies of the (near) surface. Generally speaking, such tools cannot probe the structural dynamics in a way that is representative of bulk behavior. Synchrotron X-ray diffraction based imaging has long mapped the deeply embedded structural elements, and with enhanced resolution, Dark Field X-ray Microscopy (DFXM) can now map those features with the requisite nm-resolution. However, these techniques still suffer from the required integration times due to limitations from the source and optics. This work extends DFXM to X-ray free electron lasers, showing how the $10^{12}$ photons per pulse available at these sources offer structural characterization down to 100 fs resolution (orders of magnitude faster than current synchrotron images). We introduce the XFEL DFXM setup with simultaneous bright field microscopy to probe density changes within the same volume. This work presents a comprehensive guide to the multi-modal ultrafast high-resolution X-ray microscope that we constructed and tested at two XFELs, and shows initial data demonstrating two timing strategies to study associated reversible or irreversible lattice dynamics.