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.

The development of XFELs

X-ray free-electron lasers (XFELs) have rapidly developed into unique tools for probing diverse systems of interest to different scientific disciplines with angstrom–femtosecond resolution. Claudio Pellegrini provides an overview of the milestones in the development of XFELs and their unique capabilities.

This is a preview of subscription content, access via your institution

Access options

Rent or buy this article

Get just this article for as long as you need it


Prices may be subject to local taxes which are calculated during checkout


  1. Maiman, T. Stimulated optical radiation in ruby. Nature 187, 493–494 (1960).

    Article  ADS  Google Scholar 

  2. Chapline, G. & Wood, L. X-ray lasers. Phys. Today 28, 40 (1975).

    Article  Google Scholar 

  3. Deacon, D. A. G. et al. First operation of a free-electron laser. Phys. Rev. Lett. 38, 892–894 (1977).

    Article  ADS  Google Scholar 

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

    Article  ADS  Google Scholar 

  5. Pellegrini, C. X-ray free-electron laser: from dreams to reality. Phys. Scr. T169, 014004 (2016).

    Article  ADS  Google Scholar 

  6. Pellegrini, C. A 4 to 0.1 nm FEL based on the SLAC linac. Proc. of the Workshop on 4th Generation Light Sources, (eds Cornacchia, M. and Winick, H.) 341 (Stanford Synchrotron Radiation Laboratory, 1992).

  7. Geloni, G., Huang, Z. & Pellegrini, C. in X-ray Free Electron Lasers, Applications in Materials, Chemistry and Biology Ch. 1 (eds Bergmann, U., Yachandra, V. K. & Yano, J.) (RSC, 2017).

  8. Bostedt, C. et al. Linac Coherent Light Source: the first five years. Rev. Mod. Phys. 88, 015007 (2016).

    Article  ADS  Google Scholar 

  9. Hemsing, E., Stupakov, G., Xiang, D. & Zholents, A. Beam by design: laser manipulation of electrons in modern accelerators. Rev. Mod. Phys. 86, 897 (2014).

    Article  ADS  Google Scholar 

  10. Ibrahim, M. et al. Untangling the sequence of events during the S2 → S3 transition in photosystem II and implications for the water oxidation mechanism. Proc. Natl Acad. Sci. USA (2020).

    Article  Google Scholar 

Download references


The author thanks U. Bergmann, M. Dunne, B. Denham, Z. Huang and C.-C. Kao for many useful comments. Work carried out with the support of the US Department of Energy (Contract No. DE-AC02-76F00515).

Author information

Authors and Affiliations


Corresponding author

Correspondence to Claudio Pellegrini.

Ethics declarations

Competing interests

The authors declare no competing interests.

Rights and permissions

Reprints and Permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Pellegrini, C. The development of XFELs. Nat Rev Phys 2, 330–331 (2020).

Download citation

  • Published:

  • Issue Date:

  • DOI:

This article is cited by


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