Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Tunable isolated attosecond X-ray pulses with gigawatt peak power from a free-electron laser


The quantum-mechanical motion of electrons in molecules and solids occurs on the sub-femtosecond timescale. Consequently, the study of ultrafast electronic phenomena requires the generation of laser pulses shorter than 1 fs and of sufficient intensity to interact with their target with high probability. Probing these dynamics with atomic-site specificity requires the extension of sub-femtosecond pulses to the soft X-ray spectral region. Here, we report the generation of isolated soft X-ray attosecond pulses with an X-ray free-electron laser. Our source has a pulse energy that is millions of times larger than any other source of isolated attosecond pulses in the soft X-ray spectral region, with a peak power exceeding 100 GW. This unique combination of high intensity, high photon energy and short pulse duration enables the investigation of electron dynamics with X-ray nonlinear spectroscopy and single-particle imaging, unlocking a path towards a new era of attosecond science.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Fig. 1: Diagram of the XLEAP operation.
Fig. 2: Results of the angular streaking measurement.
Fig. 3: Spectral measurements.
Fig. 4: Comparison to state-of-the-art attosecond sources.
Fig. 5: Double-pulse measurements.

Data availability

A subset of the raw data used to produce Figs. 25 is publicly available at figshare ( This repository also contains a copy of the analysis script used to invert the photoelectron momentum distributions. All other data that support the plots within this paper and other findings of this study are available from the corresponding authors on reasonable request.


  1. 1.

    Hentschel, M. et al. Attosecond metrology. Nature 414, 509–513 (2001).

    ADS  Article  Google Scholar 

  2. 2.

    Li, X. F. et al. Multiple-harmonic generation in rare gases at high laser intensity. Phys. Rev. A 39, 5751–5761 (1989).

    ADS  Article  Google Scholar 

  3. 3.

    Corkum, P. B. & Krausz, F. Attosecond science. Nat. Phys. 3, 381–387 (2007).

    Article  Google Scholar 

  4. 4.

    Chang, Z. & Corkum, P. Attosecond photon sources: the first decade and beyond [invited]. J. Opt. Soc. Am. B 27, B9–B17 (2010).

    Article  Google Scholar 

  5. 5.

    Ciappina, M. F. et al. Attosecond physics at the nanoscale. Rep. Prog. Phys. 80, 054401 (2017).

    ADS  Article  Google Scholar 

  6. 6.

    Sekikawa, T., Kosuge, A., Kanai, T. & Watanabe, S. Nonlinear optics in the extreme ultraviolet. Nature 432, 605–608 (2004).

    ADS  Article  Google Scholar 

  7. 7.

    Sansone, G. et al. Isolated single-cycle attosecond pulses. Science 314, 443–446 (2006).

    ADS  Article  Google Scholar 

  8. 8.

    Sola, I. J. et al. Controlling attosecond electron dynamics by phase-stabilized polarization gating. Nat. Phys. 2, 319–322 (2006).

    ADS  Article  Google Scholar 

  9. 9.

    Goulielmakis, E. et al. Single-cycle nonlinear optics. Science 320, 1614–1617 (2008).

    ADS  Article  Google Scholar 

  10. 10.

    Mashiko, H. et al. Double optical gating of high-order harmonic generation with carrier-envelope phase stabilized lasers. Phys. Rev. Lett. 100, 103906 (2008).

    ADS  Article  Google Scholar 

  11. 11.

    Feng, X. et al. Generation of isolated attosecond pulses with 20 to 28 femtosecond lasers. Phys. Rev. Lett. 103, 183901 (2009).

    ADS  Article  Google Scholar 

  12. 12.

    Ferrari, F. et al. High-energy isolated attosecond pulses generated by above-saturation few-cycle fields. Nat. Photon. 4, 875–879 (2010).

    ADS  Article  Google Scholar 

  13. 13.

    Takahashi, E. J., Lan, P., Mcke, O. D., Nabekawa, Y. & Midorikawa, K. Attosecond nonlinear optics using gigawatt-scale isolated attosecond pulses. Nat. Commun. 4, 2691 (2013).

    ADS  Article  Google Scholar 

  14. 14.

    Ossiander, M. et al. Attosecond correlation dynamics. Nat. Phys. 13, 280–285 (2017).

    Article  Google Scholar 

  15. 15.

    Barillot, T. R. et al. Towards XUV pump-probe experiments in the femtosecond to sub-femtosecond regime: new measurement of the helium two-photon ionization cross-section. Chem. Phys. Lett. 683, 38–42 (2017).

    ADS  Article  Google Scholar 

  16. 16.

    Bergues, B. et al. Tabletop nonlinear optics in the 100-eV spectral region. Optica 5, 237–242 (2018).

    ADS  Article  Google Scholar 

  17. 17.

    Jahn, O. et al. Towards intense isolated attosecond pulses from relativistic surface high harmonics. Optica 6, 280–287 (2019).

    ADS  Article  Google Scholar 

  18. 18.

    Teichmann, S. M., Silva, F., Cousin, S. L., Hemmer, M. & Biegert, J. 0.5-keV soft X-ray attosecond continua. Nat. Commun. 7, 11493 (2016).

    ADS  Article  Google Scholar 

  19. 19.

    Gaumnitz, T. et al. Streaking of 43-attosecond soft-X-ray pulses generated by a passively CEP-stable mid-infrared driver. Opt. Express 25, 27506–27518 (2017).

    ADS  Article  Google Scholar 

  20. 20.

    Li, J. et al. 53-attosecond X-ray pulses reach the carbon K-edge. Nat. Commun. 8, 186 (2017).

    ADS  Article  Google Scholar 

  21. 21.

    Johnson, A. S. et al. High-flux soft x-ray harmonic generation from ionization-shaped few-cycle laser pulses. Sci. Adv. 4, eaar3761 (2018).

    ADS  Article  Google Scholar 

  22. 22.

    Wolf, T. J. A. et al. Probing ultrafast ππ*/nπ* internal conversion in organic chromophores via K-edge resonant absorption. Nat. Commun. 8, 29 (2017).

    ADS  Article  Google Scholar 

  23. 23.

    Neville, S. P., Chergui, M., Stolow, A. & Schuurman, M. S. Ultrafast X-ray spectroscopy of conical intersections. Phys. Rev. Lett. 120, 243001 (2018).

    ADS  Article  Google Scholar 

  24. 24.

    Attar, A. R. et al. Femtosecond x-ray spectroscopy of an electrocyclic ring-opening reaction. Science 356, 54–59 (2017).

    ADS  Article  Google Scholar 

  25. 25.

    Schütte, B. et al. Bright attosecond soft X-ray pulse trains by transient phase-matching in two-color high-order harmonic generation. Opt. Express 23, 33947–33955 (2015).

    ADS  Article  Google Scholar 

  26. 26.

    Leone, S. R. et al. What will it take to observe processes in ’real time’? Nat. Photon. 8, 162–166 (2014).

    ADS  Article  Google Scholar 

  27. 27.

    Lépine, F., Ivanov, M. Y. & Vrakking, M. J. J. Attosecond molecular dynamics: fact or fiction? Nat. Photon. 8, 195–204 (2014).

    ADS  Article  Google Scholar 

  28. 28.

    Ackermann, W. et al. Operation of a free-electron laser from the extreme ultraviolet to the water window. Nat. Photon. 1, 336–342 (2007).

    ADS  Article  Google Scholar 

  29. 29.

    Emma, P. et al. First lasing and operation of an ångstrom-wavelength free-electron laser. Nat. Photon. 4, 641–647 (2010).

    ADS  Article  Google Scholar 

  30. 30.

    Allaria, E. et al. Highly coherent and stable pulses from the FERMI seeded free-electron laser in the extreme ultraviolet. Nat. Photon. 6, 699–704 (2012).

    ADS  Article  Google Scholar 

  31. 31.

    Allaria, E. et al. Two-stage seeded soft-X-ray free-electron laser. Nat. Photon. 7, 913–918 (2013).

    ADS  Article  Google Scholar 

  32. 32.

    Ishikawa, T. et al. A compact X-ray free-electron laser emitting in the sub-ångström region. Nat. Photon. 6, 540–544 (2012).

    ADS  Article  Google Scholar 

  33. 33.

    Kang, H.-S. et al. Hard X-ray free-electron laser with femtosecond-scale timing jitter. Nat. Photon. 11, 708–713 (2017).

    ADS  Article  Google Scholar 

  34. 34.

    Altarelli, M. The European X-ray free-electron laser facility in Hamburg. Nuclear Instrum. Methods Phys. Res. Sect. B 269, 2845–2849 (2011).

    ADS  Article  Google Scholar 

  35. 35.

    Bonifacio, R., Pellegrini, C. & Narducci, L. Collective instabilities and high-gain regime in a free-electron laser. Opt. Commun. 50, 373–378 (1984).

    ADS  Article  Google Scholar 

  36. 36.

    Pellegrini, C., Marinelli, A. & Reiche, S. The physics of x-ray free-electron lasers. Rev. Mod. Phys. 88, 015006 (2016).

    ADS  Article  Google Scholar 

  37. 37.

    Huang, Z. & Kim, K.-J. Review of x-ray free-electron laser theory. Phys. Rev. ST Accel. Beams 10, 034801 (2007).

    ADS  Article  Google Scholar 

  38. 38.

    Bonifacio, R., DeSalvo, L., Pierini, P., Piovella, N. & Pellegrini, C. Spectrum, temporal structure, and fluctuations in a high-gain free-electron laser starting from noise. Phys. Rev. Lett. 73, 70–73 (1994).

    ADS  Article  Google Scholar 

  39. 39.

    Huang, S. et al. Generating single-spike hard x-ray pulses with nonlinear bunch compression in free-electron lasers. Phys. Rev. Lett. 119, 154801 (2017).

    ADS  Article  Google Scholar 

  40. 40.

    Marinelli, A. et al. Experimental demonstration of a single-spike hard-X-ray free-electron laser starting from noise. Appl. Phys. Lett. 111, 151101 (2017).

    ADS  Article  Google Scholar 

  41. 41.

    Behrens, C. et al. Few-femtosecond time-resolved measurements of X-ray free-electron lasers. Nat. Commun. 5, 3762 (2014).

    ADS  Article  Google Scholar 

  42. 42.

    Hartmann, N. et al. Attosecond time–energy structure of X-ray free-electron laser pulses. Nat. Photon. 12, 215–220 (2018).

    ADS  Article  Google Scholar 

  43. 43.

    Zholents, A. A. Method of an enhanced self-amplified spontaneous emission for x-ray free electron lasers. Phys. Rev. ST Accel. Beams 8, 040701 (2005).

    ADS  Article  Google Scholar 

  44. 44.

    MacArthur, J. P. et al. Phase-stable self-modulation of an electron beam in a magnetic wiggler. Phys. Rev. Lett. 123, 214801 (2019).

    ADS  Article  Google Scholar 

  45. 45.

    Li, S. et al. A co-axial velocity map imaging spectrometer for electrons. AIP Adv. 8, 115308 (2018).

    ADS  Article  Google Scholar 

  46. 46.

    Kienberger, R. et al. Atomic transient recorder. Nature 427, 817–821 (2004).

    ADS  Article  Google Scholar 

  47. 47.

    Kazansky, A. K., Bozhevolnov, A. V., Sazhina, I. P. & Kabachnik, N. M. Interference effects in angular streaking with a rotating terahertz field. Phys. Rev. A 93, 013407 (2016).

    ADS  Article  Google Scholar 

  48. 48.

    Kazansky, A. K., Sazhina, I. P., Nosik, V. L. & Kabachnik, N. M. Angular streaking and sideband formation in rotating terahertz and far-infrared fields. J. Phys. B 50, 105601 (2017).

    ADS  Article  Google Scholar 

  49. 49.

    Li, S. et al. Characterizing isolated attosecond pulses with angular streaking. Opt. Express 26, 4531–4547 (2018).

    ADS  Article  Google Scholar 

  50. 50.

    Itatani, J. et al. Attosecond streak camera. Phys. Rev. Lett. 88, 173903 (2002).

    ADS  Article  Google Scholar 

  51. 51.

    Glownia, J. M. et al. Time-resolved pump-probe experiments at the LCLS. Opt. Express 18, 17620–17630 (2010).

    ADS  Article  Google Scholar 

  52. 52.

    Zhang, Z., Duris, J., MacArthur, J. P., Huang, Z. & Marinelli, A. Double chirp-taper x-ray free-electron laser for attosecond pump-probe experiments. Phys. Rev. Accel. Beams 22, 050701 (2019).

    ADS  Article  Google Scholar 

  53. 53.

    Ding, Y., Huang, Z., Ratner, D., Bucksbaum, P. & Merdji, H. Generation of attosecond x-ray pulses with a multicycle two-color enhanced self-amplified spontaneous emission scheme. Phys. Rev. ST Accel. Beams 12, 060703 (2009).

    ADS  Article  Google Scholar 

  54. 54.

    Mukamel, S., Healion, D., Zhang, Y. & Biggs, J. D. Multidimensional attosecond resonant X-ray spectroscopy of molecules: lessons from the optical regime. Annu. Rev. Phys. Chem. 64, 101–127 (2013).

    ADS  Article  Google Scholar 

  55. 55.

    Lutman, A. A. et al. Experimental demonstration of femtosecond two-color x-ray free-electron lasers. Phys. Rev. Lett. 110, 134801 (2013).

    ADS  Article  Google Scholar 

  56. 56.

    Schoenlein, R. et al. New Science Opportunities Enabled by LCLS-II X-ray Lasers SLAC Pub. SLAC-R-1053 (SLAC National Accelerator Laboratory, 2015).

  57. 57.

    Marinelli, A. et al. Multicolor operation and spectral control in a gain-modulated X-ray free-electron laser. Phys. Rev. Lett. 111, 134801 (2013).

    ADS  Article  Google Scholar 

  58. 58.

    Schweigert, I. V. & Mukamel, S. Probing valence electronic wave-packet dynamics by all X-ray stimulated Raman spectroscopy: a simulation study. Phys. Rev. A 76, 012504 (2007).

    ADS  Article  Google Scholar 

Download references


We would like to acknowledge T. Gorkhover, C. Bostedt, C. Pellegrini, A. Cavalieri, N. Berrah, L. Young, L. F. DiMauro, H.-D. Nuhn, G. Marcus, T. Maxwell, M. Dunne, M. Minitti and R. Schoenlein for useful discussions and suggestions. We would also like to acknowledge M. Merritt, O. Schmidt, N. Strelnikov and I. Vasserman for their assistance in designing, constructing and installing the XLEAP wiggler. We also acknowledge the SLAC Accelerator Operations and the LCLS operations group, and the Mechanical and Electrical engineering divisions of the SLAC Accelerator Directorate, especially G. Kraft, M. Carrasco, A. Cedillos, K. Luchini, D. Bohler and J. Mock for their invaluable support. This work was supported by US Department of Energy contract nos. DE-AC02-76SF00515, DOE-BES Accelerator and detector research program Field Work Proposal 100317, DOE-BES, Chemical Sciences, Geosciences, and Biosciences Division, and Department of Energy, Laboratory Directed Research and Development program at SLAC National Accelerator Laboratory, under contract DE-AC02-76SF00515. W.H. acknowledges financial support by the BACATEC programme. P.R. and M.F.K. acknowledge additional support by the DFG via KL-1439/10, and the Max Planck Society. G.H. acknowledges the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) Projektnummer 328961117 SFB 1319 ELCH. A.Z. and J.Z.X. acknowledge support by the US Department of Energy contract no. DE-AC02-06CH11357. J.P.Marangos and T.D. acknowledge support by EPSRC programme grant EP/R019509/1.

Author information




A.M. and J.P.C. conceived the experiment, led the experimental team and data analysis and co-wrote the article. J.D. led the electron bunch shaping experimental work and spectral measurement, analysed the spectral data and co-wrote the paper. S.L. designed and built the streaking instrument, participated in the streaking experiment, performed the streaking data analysis and co-wrote the article. T.D. and E.G.C. participated in the streaking experiment, contributed to the streaking data analysis and co-wrote the article. J.P.MacArthur, A.A.L. and Z.Z. participated in the streaking experiment and the electron bunch experimental development, and co-wrote the article. P.R., J.W.A., G.C., J.M.G., G.H., A.K., J.Knurr, J.Krzywinski, M.-F.L., M.N., J.T.O’N., N.S., P.W., A.L.W., T.J.A.W. and M.F.K. participated in the streaking experiment and co-wrote the article. J.Z.X. designed the magnetic wiggler and oversaw the construction of the magnetic wiggler and co-wrote the article. F.-J.D. contributed to the electron bunch shaping development and co-wrote the article. A.Z. helped conceive the experiment and contributed to the design of the magnetic wiggler and co-wrote the article. J.J.W. helped conceive and design the XLEAP beamline and co-wrote the article. Z.H. helped conceive the experiment and design the XLEAP beamline, participated in the electron bunch shaping experiments and co-wrote the article. P.H.B., W.H., A.N. and R.C. helped conceive and participated in the streaking experiment and co-wrote the article. J.P.Marangos helped conceive the experiment and co-wrote the article.

Corresponding authors

Correspondence to James P. Cryan or Agostino Marinelli.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Supplementary Information

Beam dynamics, angular streaking set-up, reconstruction algorithm and pulse properties.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Duris, J., Li, S., Driver, T. et al. Tunable isolated attosecond X-ray pulses with gigawatt peak power from a free-electron laser. Nat. Photonics 14, 30–36 (2020).

Download citation

Further reading


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing