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Towards jitter-free ultrafast electron diffraction technology


Stroboscopic visualization of nuclear or electron dynamics in atoms, molecules or solids requires ultrafast pump and probe pulses and a close to perfect synchronization between the two. We have developed a 3 MeV ultrafast electron diffraction (UED) probe technology that nominally reduces the electron bunch duration and the arrival time jitter to the subfemtosecond level. This simple configuration uses a radiofrequency photogun and a 90° achromatic bend and is designed to provide effectively jitter-free conditions. Terahertz streaking measurements reveal an electron bunch duration of 25 fs, even for a charge as high as 0.6 pC, and an arrival time jitter of 7.8 fs, the latter limited by only the measurement accuracy. From pump–probe measurements of photoexcited bismuth films, the instrument response function was determined to be 31 fs. This pioneering jitter-free technique paves the way towards UED of attosecond phenomena in atomic, molecular and solid-state dynamics.

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Fig. 1: Schematic of the UED beamline and simulated temporal characteristics of an electron bunch.
Fig. 2: Simulated arrival time jitter of electron beams.
Fig. 3: THz streaking experiment.
Fig. 4: Comparison of the simulated and measured electron bunch duration and jitter.
Fig. 5: Dynamics of the (300) peak intensities of polycrystalline Bi.

Data availability

The data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request.


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This work was supported by the World Class Institute (WCI) Program of the National Research Foundation of Korea (NRF), funded by the Ministry of Science, ICT and Future Planning (NRF grant no. WCI 2011-001), and an internal R&D programme at KAERI funded by the Ministry of Science and ICT (MSIT) of the Republic of Korea (525350-19), and partially supported by the University of Science and Technology (UST) UST Young Scientist Research Program, through the University of Science and Technology (no. 2017-YS-06), and a National Research Council of Science & Technology (NST) grant by the Korea government (MSIT) (no. CAP-18-05-KAERI). T.F. acknowledges funding from the Swiss National Science Foundation (SNSF) under grant no. 200020-178812.

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Authors and Affiliations



H.W.K., N.A.V., K.Y.O., K-H.J., S.H.P., S.P., T.F. and Y.U.J. carried out the UED and THz streaking experiment. I.H.B., M.H.K., Y.C.K., K.L. and F.R. led the THz and optical characterization experiments. J.S. and J.K. carried out the synchronization between the laser and RF signal. S.C. carried out the bismuth sample growth. H.W.K., N.A.V. and K.Y.O. carried out the simulations and performed the data analysis. H.W.K. and Y.U.J. wrote the manuscript, with input from all authors.

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Correspondence to Young Uk Jeong.

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Supplementary Figs. 1 and 2, materials and methods, Table 1 and equations (1)–(6).

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Kim, H.W., Vinokurov, N.A., Baek, I.H. et al. Towards jitter-free ultrafast electron diffraction technology. Nat. Photonics 14, 245–249 (2020).

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