标题： 二象性：从单一衍射图样中获得两帧超快成像 显示英文标题

标题： Dichography: Two-frame Ultrafast Imaging from a Single Diffraction Pattern

摘要： X射线自由电子激光如今可以提供具有可调延迟的不同光子能量的超亮、超短光脉冲对。 当与衍射实验结合时，这些脉冲在不同时间与样品的相互作用可以产生演化系统的两个快照，从而实现纳米物质在太赫兹时间尺度及以上的空间和时间分辨率。 然而，光探测器的速度要慢几个数量级。 来自两个脉冲的衍射信号在记录的数据中重叠，无法使用目前可用的分析方法进行分离。 在这里，我们通过引入Dichography（二象术）来解决这一挑战，这是一种衍射成像技术，可以从叠加的散射信号中恢复出样品的两个独特视图。 我们将Dichography应用于使用接近检测极限强度的时间延迟、双色X射线脉冲成像的孤立氙掺杂超流氦纳米滴的实验衍射图样。 重建的图像提供了氙结构在与第一束脉冲相互作用后750飞秒内仍存在的证据。 通过将该方法应用于第二个实验的数据，进一步探索了Dichography的能力，在该实验中，我们获取了被同一束光脉冲拦截的两个不同银纳米颗粒的图像。 Dichography为在空间和时间上解析超快现象开辟了一类新的实验，向X射线自由电子激光最初承诺的捕捉纳米物质超快电影的目标迈出了重要一步。 显示英文摘要

摘要： X-ray free-electron lasers can nowadays deliver pairs of ultrabright, ultrashort light pulses with controllable delays at different photon energies. When combined with diffraction experiments, the interaction of these pulses with a sample at different times can produce two snapshots of an evolving system, enabling spatial and temporal resolution of ultrafast dynamics in nanomatter at and beyond the terahertz time scale. However, light detectors are orders of magnitude slower. The diffraction signals from the two pulses overlap in the recorded data and cannot be separated using currently available analysis methods. Here, we address this challenge by introducing Dichography, a diffraction imaging technique that restores the two unique views of the sample from superimposed scattering signals. We apply Dichography to experimental diffraction patterns of isolated xenon-doped superfluid helium nanodroplets, imaged using time-delayed, two-color X-ray pulses at intensities near the detection limit. The reconstructed images provide evidence of the survival of the xenon structures up to 750 fs after the interaction with the first shot. The capabilities of Dichography are further explored by applying the method to data from a second experiment, in which we retrieve the images of two distinct silver nanoparticles intercepted by the same light pulse. Dichography enables a new class of experiments for spatially and temporally resolving ultrafast phenomena, making a significant step toward the original promise of X-ray free-electron lasers to capture ultrafast movies of nanomatter.