Ångstrom and attosecond are the fundamental spatiotemporal scales for electron dynamics in various materials. Although attosecond pulses with wavelengths comparable to the atomic scales are expected to be a key tool in advancing attosecond science, producing high-power hard X-ray attosecond pulses at ångstrom wavelengths remains a formidable challenge. Here, we report the generation of terawatt-scale attosecond hard X-ray pulses using a free-electron laser in a special operation mode. We achieved 9 keV single-spike X-ray pulses with a mean pulse energy of around 180 μJ, exceeding previous reports by more than an order of magnitude, and an estimated average pulse duration of 200 as at full-width at half-maximum. Exploiting the unique capability of the European XFEL, which can deliver ten pulse trains per second with each containing hundreds of pulses at megahertz repetition rates, this study demonstrates the generation of attosecond X-ray pulses at a 2.25 MHz repetition rate. These intense high-repetition-rate attosecond X-ray pulses present transformative prospects for structural and electronic damage-free X-ray measurements and attosecond time-resolved X-ray methodologies, heralding a new era in ultrafast X-ray science.

Ångstrom 和 attosecond 是各种材料中电子动力学的基本时空尺度。尽管具有与原子尺度相当的波长的阿秒脉冲有望成为推进阿秒科学的关键工具，但在 ångstrom 波长下产生高功率硬 X 射线阿秒脉冲仍然是一项艰巨的挑战。在这里，我们报道了在特殊操作模式下使用自由电子激光器产生太瓦级阿秒硬 X 射线脉冲的过程。我们实现了 9 keV 的单尖峰 X 射线脉冲，平均脉冲能量约为 180 μJ，比以前的报告高出一个数量级以上，估计半峰全宽平均脉冲持续时间为 200。利用欧洲 XFEL 的独特功能，每秒可以提供 10 个脉冲序列，每个脉冲序列包含数百个兆赫兹重复率的脉冲，本研究展示了以 2.25 MHz 重复频率产生阿秒 X 射线脉冲。这些强烈的高重复频率阿秒 X 射线脉冲为结构和电子无损伤 X 射线测量以及阿秒时间分辨 X 射线方法带来了变革性的前景，预示着超快 X 射线科学的新时代。