AI 中文总结
本研究针对XFEL应用于无机和小分子晶体学及固体电荷密度研究时的电子损伤问题，提出用阿秒硬X射线脉冲成像，模拟显示其可降低电子激发，为XFEL衍射成像开辟新前景。
AI 中文摘要
迄今为止，利用X射线自由电子激光（XFEL）脉冲进行最先进结构测定的研究重点一直是大分子晶体学，该方法在求解尺寸小于几微米的微晶结构方面取得了显著成功，这类微晶难以用常规同步辐射光源进行研究。然而，由于无机和小分子晶体样品中会发生快速电子激发，XFEL在这些领域的成功应用受到限制，这一问题也阻碍了XFEL在固体电荷密度研究中的使用。本研究提出利用硬X射线脉冲（阿秒级持续时间）对有机和无机体系进行电荷密度的X射线成像。对受辐照金刚石和硅的模拟结果显示，在固定光子能量和脉冲注量条件下，阿秒X射线脉冲可持续降低电子激发；在相同条件下，提高X射线光子能量可进一步减少瞬态电子损伤。这些理论预测为可视化价电子分布提供了强大且有充分依据的策略，为XFEL的衍射成像研究开辟了新前景。
英文摘要
So far, the focus of state-of-the-art structure determination using x-ray free-electron laser (XFEL) pulses has been on macromolecular crystallography. This approach has achieved remarkable success in solving the structure of microcrystals smaller than a few micrometres, which are difficult to investigate using conventional synchrotron sources. However, successful applications of XFELs to inorganic and small-molecule crystallography have been limited due to rapid electron excitation in these samples. This same issue has also prevented the use of XFELs in charge-density studies of solids. In this study, we propose using hard x-ray pulses with an attosecond duration for x-ray imaging of charge density in organic and inorganic systems. Simulations of irradiated diamond and silicon showed that attosecond x-ray pulses consistently reduce the electronic excitation for a fixed photon energy and pulse fluence. Further reduction of transient electronic damage can be achieved by increasing the x-ray photon energy under these conditions. These theoretical predictions demonstrate a powerful and well-founded strategy for visualizing valence-electron distribution, opening up new prospects for diffraction imaging studies with XFELs.
Comments7 pages, 3 figures, 2 tables
