We demonstrate a noninvasive time-sorting method for ultrafast electron diffraction (UED) experiments with radio frequency (rf)-compressed electron beams. We show that electron beam energy and arrival time at the sample after the rf compression are strongly correlated, such that the arrival time jitter may be corrected through the measurement of the beam energy. The method requires minimal change to the infrastructure of most of the UED machines and is applicable to both keV and MeV UED. In our experiment with ∼3 MeV beam, the timing jitter after the rf compression is corrected with a 35-fs root mean square (rms) accuracy, limited by the $3\times {10}^{-4}$ energy stability. For keV UED with a high energy stability, sub-10 fs accuracy in time-sorting should be readily achievable. This time-sorting technique allows us to retrieve the 2.5 THz oscillation related to coherent A_1g phonon in the laser-excited Bismuth film and extends the temporal resolution of UED to a regime far beyond the 100–200 fs rms jitter limitation.

中文翻译：

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射频压缩超快电子衍射中的无创时间分选

我们展示了一种使用射频 (rf) 压缩电子束进行超快电子衍射 (UED) 实验的无创时间排序方法。我们表明，射频压缩后电子束能量和到达样品的时间密切相关，因此可以通过测量束能量来校正到达时间抖动。该方法需要对大多数 UED 机器的基础设施进行最少的更改，并且适用于 keV 和 MeV UED。在我们使用~3 MeV 光束的实验中，射频压缩后的定时抖动以 35-fs 的均方根 (rms) 精度进行校正，受$3\times {10}^{-4}$能量稳定性。对于具有高能量稳定性的 keV UED，时间排序的亚 10 fs 精度应该很容易实现。这种时间排序技术使我们能够在激光激发的铋膜中检索与相干 A _{1 g}声子相关的 2.5 THz 振荡，并将 UED 的时间分辨率扩展到远远超出 100-200 fs rms 抖动限制的范围。