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.

Multiple ionization of atom clusters by intense soft X-rays from a free-electron laser


Intense radiation from lasers has opened up many new areas of research in physics and chemistry, and has revolutionized optical technology. So far, most work in the field of nonlinear processes has been restricted to infrared, visible and ultraviolet light1, although progress in the development of X-ray lasers has been made recently2. With the advent of a free-electron laser in the soft-X-ray regime below 100 nm wavelength3, a new light source is now available for experiments with intense, short-wavelength radiation that could be used to obtain deeper insights into the structure of matter. Other free-electron sources with even shorter wavelengths are planned for the future. Here we present initial results from a study of the interaction of soft X-ray radiation, generated by a free-electron laser, with Xe atoms and clusters. We find that, whereas Xe atoms become only singly ionized by the absorption of single photons, absorption in clusters is strongly enhanced. On average, each atom in large clusters absorbs up to 400 eV, corresponding to 30 photons. We suggest that the clusters are heated up and electrons are emitted after acquiring sufficient energy. The clusters finally disintegrate completely by Coulomb explosion.

Your institute does not have access to this article

Relevant articles

Open Access articles citing this article.

Access options

Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: Time-of-flight (TOF) mass spectra of ionization products of Xe atoms and clusters.
Figure 2: TOF mass spectra recorded after irradiation of 1,500-atom Xe clusters as a function of power density.
Figure 3: Classical simulations of the electron motion and ionization for Xe13 clusters after irradiation with infrared radiation and soft X-rays.
Figure 4: Schematic illustration of the ionization of Xe clusters and a subsequent Coulomb explosion.


  1. Batani, D., Joachain, C. J., Martellucci, S. & Chester, A. N. Atoms, Solids, and Plasmas in Super-Intense Laser Fields (Kluwer Academic, New York, 2001)

    Book  Google Scholar 

  2. Smith, R. & Key, M. H. X-Ray Lasers 2000 (eds Jamelot, L. G., Möller, C. & Klinsnick, A.) 383–388 (EDP Science, Saint Malo, 2000)

    Google Scholar 

  3. Andruszkow, J. et al. First observation of self-amplified spontaneous emission in a free-electron laser at 109 nm wavelength. Phys. Rev. Lett. 85, 3825–3828 (2000)

    ADS  CAS  Article  Google Scholar 

  4. Ayvazyan, V. et al. Generation of GW radiation pulses from a VUV free-electron laser operating in the femtosecond regime. Phys. Rev. Lett. 88, 104802 (2002)

    ADS  CAS  Article  Google Scholar 

  5. Åberg, T., et al. DESY Report TESLA FEL 95-03 (DESY, Hamburg, 1995)

    Google Scholar 

  6. Materlik, G. & Tschentscher, T. (eds) DESY Report TESLA FEL 2001-05 (DESY, Hamburg, 2001)

  7. Shenoy, G. K. & Stöhr, J. LCLS: The First Experiments (SLAC, Stanford, 2000).

  8. Neutze, R., Wouts, R., van der Spoel, D., Weckert, E. & Haidu, J. Potential for biomolecular imaging with femtoscond X-ray pulses. Nature 406, 752–757 (2000)

    ADS  CAS  Article  Google Scholar 

  9. Russek, M., Lagadec, H. & Blenski, T. Cluster explosion in an intense laser pulse: Thomas-Fermi model. Phys. Rev. A 63, 13203 (2000)

    Article  Google Scholar 

  10. Synder, E. M., Buzza, S. A. & Castleman, A. W. Jr Intense field matter interactions: Multiple ionisation of clusters. Phys. Rev. Lett. 77, 3347–3350 (1996)

    ADS  Article  Google Scholar 

  11. Ditmire, T. et al. High-energy ions produced in explosions of superheated atomic clusters. Nature 386, 54–56 (1997)

    ADS  CAS  Article  Google Scholar 

  12. Ditmire, T., Donnelly, T., Rubenchik, A. M., Falcone, R. W. & Perry, M. D. Interaction of intense pulses with atomic clusters. Phys. Rev. A 53, 3379–3402 (1996)

    ADS  CAS  Article  Google Scholar 

  13. Lezius, M., Dobosz, S., Normand, D. & Schmidt, M. Explosion dynamics of rare gas clusters in strong laser fields. Phys. Rev. Lett. 80, 261–264 (1998)

    ADS  CAS  Article  Google Scholar 

  14. Köller, L. et al. Plasmon-enhanced multi-ionization of small metal clusters in strong femtosecond laser fields. Phys. Rev. Lett. 82, 3783–3786 (1999)

    ADS  Article  Google Scholar 

  15. Shao, Y. L. et al. Multi-keV electron generation in the interaction of intense laser pulses with Xe clusters. Phys. Rev. Lett. 77, 3343–3346 (1996)

    ADS  CAS  Article  Google Scholar 

  16. Rose-Petruck, C., Schafer, K. J., Wilson, K. R. & Barty, C. P. J. Ultrafast electron dynamics and inner-shell ionization in laser driven clusters. Phys. Rev. A 55, 1182–1190 (1996)

    ADS  Article  Google Scholar 

  17. Last, I. & Jortner, J. Quasiresonance ionization of large multicharged clusters in a strong laser field. Phys. Rev. A 60, 2215–2221 (1999)

    ADS  CAS  Article  Google Scholar 

  18. Last, I. & Jortner, J. Dynamics of the Coulomb explosion of large clusters in a strong laser field. Phys. Rev. A 62, 13201 (2000)

    ADS  Article  Google Scholar 

  19. Brewczyk, M., Clark, C. W., Lewenstein, M. & Rzazewski, K. Stepwise explosion of atomic clusters induced by a strong laser field. Phys. Rev. Lett. 80, 1857–1860 (1998)

    ADS  CAS  Article  Google Scholar 

  20. Krainov, V. P. & Roshchupin, A. S. Dynamics of Coulomb explosion of large Xe clusters irradiated by a super-intense ultra-short laser pulse. J. Phys. B 34, L297–L303 (2001)

    ADS  CAS  Article  Google Scholar 

  21. McPherson, A., Thompson, B. D., Borisov, A. B., Boyer, K. & Rhodes, C. K. Multiphoton-induced X-ray emission at 4-5 keV from Xe atoms with multiple core vacancies. Nature 370, 631–634 (1994)

    ADS  CAS  Article  Google Scholar 

  22. Brewczyk, M. & Rzazewski, K. Over-the-barrier ionization of multi electron atoms by intense VUV free-electron laser. J. Phys. B 32, L1–L4 (1999)

    ADS  CAS  Article  Google Scholar 

  23. Delone, N. B. & Krainov, V. P. Multiphoton Process in Atoms (ed. Lambropoulos, P.) 1–3 (Springer, Berlin, 2000)

    Google Scholar 

  24. Samson, J. A. R. New energy levels in xenon and krypton. Phys. Lett. 8, 107–108 (1964)

    ADS  CAS  Article  Google Scholar 

  25. Aust, S., Strickland, D., Meyerhofer, D. D., Chin, S. L. & Eberly, J. H. Tunneling ionization of noble gases in a high-intensity laser field. Phys. Rev. Lett. 63, 2212–2215 (1989)

    ADS  Article  Google Scholar 

  26. Brunel, F. Not-so resonant, resonant absorption. Phys. Rev. Lett. 59, 52–55 (1987)

    ADS  CAS  Article  Google Scholar 

  27. Kostyukov, I. Y. Inverse-bremsstrahlung absorption of an intense laser field in cluster plasma. JETP Lett. 73, 393–397 (2001)

    ADS  CAS  Article  Google Scholar 

  28. Hagena, O. F. Condensation in free jets: Comparison of rare gases and metals. Z. Phys. D 4, 291–299 (1987)

    ADS  CAS  Article  Google Scholar 

  29. Karnbach, R., Joppien, M., Stapelfeldt, J., Wörmer, J. & Möller, T. CLULU: An experimental setup for luminescence measurements on van der Waals clusters with synchrotron radiation. Rev. Sci. Instrum. 64, 2838–2849 (1993)

    ADS  CAS  Article  Google Scholar 

Download references


We thank the TTF team at DESY, especially P. Castro, M. Minty, D. Nölle, H. Schlarb and S. Schreiber, for running the accelerator; we also thank J. R. Schneider for support and discussions. The first group of authors (H.W. to T.M.) built the apparatus for the cluster experiment and performed the experiment; the second group of authors (B.F. to M.Y) worked on the FEL and the diagnostics. We thank K.H. Meiwes-Broer, T. Brabec, C. Rose-Petruck, J. Krzywinski, M. Lezius, I. Kostyukov, J.M. Rost, E. Rühl, U. Saalman, J. Jortner and M. Smirnov and their research groups for discussions and comments, and J. Sutter for critically reading the manuscript. This work was supported by the DFG.

Author information

Authors and Affiliations


Corresponding author

Correspondence to T. Möller.

Ethics declarations

Competing interests

The authors declare that they have no competing financial interests.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Wabnitz, H., Bittner, L., de Castro, A. et al. Multiple ionization of atom clusters by intense soft X-rays from a free-electron laser. Nature 420, 482–485 (2002).

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI:

Further reading


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.


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