Skip to main content

Thank you for visiting nature.com. 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.

  • Article
  • Published:

Direct identification of Ac and No molecules with an atom-at-a-time technique

Nature volume 644, pages 376–380 (2025)Cite this article

Subjects

Abstract

The periodic table provides an intuitive framework for understanding chemical properties. However, its traditional patterns may break down for the heaviest elements occupying the bottom of the chart. The large nuclei of actinides (Z > 88) and superheavy elements (Z ≥ 104) give rise to relativistic effects that are expected to substantially alter their chemical behaviours, potentially indicating that we have reached the end of a predictive periodic table1. Relativistic effects have already been cited for the unusual chemistry of the actinides compared with those of their lanthanide counterparts2. Unfortunately, it is difficult to understand the full impact of relativistic effects, as research on the later actinides and superheavy elements is scarce. Beyond fermium (Z = 100), elements need to be produced and studied one atom at a time, using accelerated ion beams and state-of-the-art experimental approaches. So far, no experiments have been capable of directly identifying produced molecular species. Here ions of actinium (Ac, Z = 89) and nobelium (No, Z = 102) were synthesized through nuclear reactions at the 88-Inch Cyclotron facility at Lawrence Berkeley National Laboratory and then exposed to trace amounts of H2O and N2. The produced molecular species were directly identified by measuring their mass-to-charge ratios using FIONA (For the Identification Of Nuclide A)3. These results mark the first, to our knowledge, direct identification of heavy-element molecular species using an atom-at-a-time technique and highlight the importance of such identifications in future superheavy-element chemistry experiments to deepen understanding of their chemical properties.

Access through your institution
Buy or subscribe

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

Access options

Access through your institution

Buy this article

  • Purchase on SpringerLink
  • Instant access to full article PDF
Buy now

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

Fig. 1: Schematic of the BGS and FIONA devices at the LBNL 88-Inch Cyclotron facility.
Fig. 2: FIONA measurements of actinium and nobelium molecules.
Fig. 3: Comparison of actinium and nobelium molecule production.

Similar content being viewed by others

Data availability

The data to support the findings of this study are available on Zenodo (https://zenodo.org/records/14277708)53.

Code availability

The code used to analyse the findings of this study is available on Zenodo (https://zenodo.org/records/14277708)53.

References

  1. Smits, O. R., Düllmann, C. E., Indelicato, P., Nazarewicz, W. & Schwerdtfeger, P. The quest for superheavy elements and the limit of the periodic table. Nat. Rev. Phys. 2, 515–531 (2020).

    Google Scholar 

  2. The Chemistry of the Actinide and Transactinide Elements Vol. 1–5 (Springer, 2006).

  3. Gates, J. M. & Pore, J. L. Studies of heavy and super heavy elements with FIONA: the broad impact of mass-number identifications. Eur. Phys. J. A 58, 196 (2022).

    Article  ADS  CAS  Google Scholar 

  4. Miederer, M., Scheinberg, D. A. & McDevitt, M. R. Realizing the potential of the actinium-225 radionuclide generator in targeted alpha particle therapy applications. Adv. Drug Deliv. Rev. 60, 1371–1382 (2008).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  5. Deblonde, G. J.-P., Zavarin, M. & Kersting, A. B. The coordination properties and ionic radius of actinium: a 120-year-old enigma. Coord. Chem. Rev. 446, 214130 (2021).

    Article  CAS  Google Scholar 

  6. Wacker, J. N. et al. Actinium chelation and crystallization in a macromolecular scaffold. Nat. Commun. 15, 5741 (2024).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  7. Silva, R. J. in The Chemistry of the Actinide and Transactinide Elements (eds Morss, L. R., Edelstein, N. M. & Fuger, J.) 1621–1651 (Springer, 2006).

  8. Sato, T. K. et al. First ionization potentials of Fm, Md, No, and Lr: verification of filling-up of 5f electrons and confirmation of the actinide series. J. Am. Chem. Soc. 140, 14609–14613 (2018).

    Article  CAS  PubMed  Google Scholar 

  9. Laatiaoui, M. et al. Atom-at-a-time laser resonance ionization spectroscopy of nobelium. Nature 538, 495–498 (2016).

    Article  ADS  PubMed  Google Scholar 

  10. Schädel, M. Chemistry of the superheavy elements. Philos. Trans. R. Soc. A Math. Phys. Eng. Sci. 373, 20140191 (2015).

    Article  ADS  Google Scholar 

  11. Gregorich, K. E. Simulation of recoil trajectories in gas-filled magnetic separators. Nucl. Instrum. Methods Phys. Res. A 711, 47–59 (2013).

    Article  ADS  CAS  Google Scholar 

  12. Savard, G. Large radio-frequency gas catchers and the production of radioactive nuclear beams. J. Phys. Conf. Ser. 312, 052004 (2011).

    Article  Google Scholar 

  13. Cooper, K. et al. Extraction of thermalized projectile fragments from a large volume gas cell. Nucl. Instrum. Methods Phys. Res. A 763, 543–546 (2014).

    Article  ADS  CAS  Google Scholar 

  14. Sumithrarachchi, C. S. et al. Beam thermalization in a large gas catcher. Nucl. Instrum. Methods Phys. Res. B 463, 305–309 (2020).

    Article  ADS  CAS  Google Scholar 

  15. Anderson, J. B., Andres, R. P. & Fenn, J. B. in Advances in Chemical Physics: Molecular Beams Vol. 10 (ed. Ross, J.) 275–317 (Interscience, 1966).

  16. Hillenkamp, M., Keinan, S. & Even, U. Condensation limited cooling in supersonic expansions. J. Chem. Phys. 118, 8699–8705 (2003).

    Article  ADS  CAS  Google Scholar 

  17. Northby, J. A. Experimental studies of helium droplets. J. Chem. Phys. 115, 10065–10077 (2001).

    Article  ADS  CAS  Google Scholar 

  18. Searcy, J. Q. & Fenn, J. B. Clustering of water on hydrated protons in a supersonic free jet expansion. J. Chem. Phys. 61, 5282–5288 (1974).

    Article  ADS  CAS  Google Scholar 

  19. Herfurth, F. et al. A linear radiofrequency ion trap for accumulation, bunching, and emittance improvement of radioactive ion beams. Nucl. Instrum. Methods Phys. Res. A 469, 254–275 (2001).

    Article  ADS  CAS  Google Scholar 

  20. Lunney, M. D. & Moore, R. B. Cooling of mass-separated beams using a radiofrequency quadrupole ion guide. Int. J. Mass Spectrom. 190–191, 153–160 (1999).

    Article  Google Scholar 

  21. Mansell, S. M., Farnaby, J. H., Germeroth, A. I. & Arnold, P. L. Thermally stable uranium dinitrogen complex with siloxide supporting ligands. Organometallics 32, 4212–4218 (2013).

    Article  Google Scholar 

  22. Schädel, M. et al. Chemical properties of element 106 (seaborgium). Nature 388, 55–57 (1997).

    Article  ADS  Google Scholar 

  23. Eichler, R. et al. Chemical characterization of bohrium (element 107). Nature 407, 63–65 (2000).

    Article  ADS  CAS  PubMed  Google Scholar 

  24. Düllmann, Ch. E. et al. Chemical investigation of hassium (element 108). Nature 418, 859–862 (2002).

    Article  ADS  PubMed  Google Scholar 

  25. Eichler, R. et al. Chemical characterization of element 112. Nature 447, 72–75 (2007).

    Article  ADS  CAS  PubMed  Google Scholar 

  26. Even, J. et al. Synthesis and detection of a seaborgium carbonyl complex. Science 345, 1491–1493 (2014).

    Article  ADS  CAS  PubMed  Google Scholar 

  27. Eichler, R. et al. Indication for a volatile element 114. Radiochim. Acta 98, 133–139 (2010).

    Article  CAS  Google Scholar 

  28. Yakushev, A. et al. Superheavy element flerovium (element 114) is a volatile metal. Inorg. Chem. 53, 1624–1629 (2014).

    Article  MathSciNet  CAS  PubMed  Google Scholar 

  29. Yakushev, A. et al. On the adsorption and reactivity of element 114, flerovium. Front. Chem. 10, 976635 (2022).

    Article  ADS  CAS  PubMed  PubMed Central  Google Scholar 

  30. Yakushev, A. et al. Manifestation of relativistic effects in the chemical properties of nihonium and moscovium revealed by gas chromatography studies. Front. Chem. 12, 1474820 (2024).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  31. Rutkowski, P. X. et al. Hydration of gas-phase ytterbium ion complexes studied by experiment and theory. Theor. Chem. Acc. 129, 575–592 (2011).

    Article  CAS  Google Scholar 

  32. Cheng, P., Koyanagi, G. K. & Bohme, D. K. Gas-phase reactions of atomic lanthanide cations with D2O: room-temperature kinetics and periodicity in reactivity. ChemPhysChem 7, 1813–1819 (2006).

    Article  CAS  PubMed  Google Scholar 

  33. Cheng, P., Koyanagi, G. K. & Bohme, D. K. Heavy water reactions with atomic transition-metal and main-group cations: gas phase room-temperature kinetics and periodicities in reactivity. J. Phys. Chem. A 111, 8561–8573 (2007).

    Article  CAS  PubMed  Google Scholar 

  34. Gates, J. M. et al. First direct measurements of superheavy-element mass numbers. Phys. Rev. Lett. 121, 222501 (2018).

    Article  ADS  CAS  PubMed  Google Scholar 

  35. Leitner, D. et al. Next generation ECR ion sources: first results of the superconducting 28 GHz ECRIS—VENUS. Nucl. Instrum. Methods Phys. Res. B 235, 486 (2005).

    Article  ADS  CAS  Google Scholar 

  36. Parr, R. G. & Yang, W. Density-Functional Theory of Atoms and Molecules (Oxford Univ. Press, 1989).

  37. Becke, A. D. Density‐functional thermochemistry. III. The role of exact exchange. J. Chem. Phys. 98, 5648–5652 (1993).

    Article  ADS  CAS  Google Scholar 

  38. Lee, C., Yang, W. & Parr, R. G. Development of the Colle-Salvetti correlation-energy formula into a functional of the electron density. Phys. Rev. B 37, 785–789 (1988).

    Article  ADS  CAS  Google Scholar 

  39. Kendall, R. A., Dunning, T. H. Jr & Harrison, R. J. Electron affinities of the first-row atoms revisited. Systematic basis sets and wave functions. J. Chem. Phys. 96, 6796–6806 (1992).

    Article  ADS  CAS  Google Scholar 

  40. Cao, X. & Dolg, M. Segmented contraction scheme for small-core actinide pseudopotential basis sets. J. Mol. Struct. THEOCHEM 673, 203–209 (2004).

    Article  CAS  Google Scholar 

  41. Cao, X., Dolg, M. & Stool, M. Valence basis sets for relativistic energy-consistent small-core actinide pseudopotentials. J. Chem. Phys. 118, 487–496 (2003).

    Article  ADS  CAS  Google Scholar 

  42. Bartlett, R. J. & Musial, M. Coupled-cluster theory in quantum chemistry. Rev. Mod. Phys. 79, 291–352 (2007).

    Article  ADS  CAS  Google Scholar 

  43. Jong, W. A., de Harrison, R. J. & Dixon, D. A. Parallel Douglas–Kroll energy and gradients in NWChem: estimating scalar relativistic effects using Douglas–Kroll contracted basis sets. J. Chem. Phys. 114, 48–53 (2001).

    Article  ADS  Google Scholar 

  44. Feng, R. & Peterson, K. A. Correlation consistent basis sets for actinides. II. The atoms Ac and Np–Lr. J. Chem. Phys. 147, 084108 (2017).

    Article  ADS  PubMed  Google Scholar 

  45. Wolf, A., Reiher, M. & Hess, B. A. The generalized Douglas–Kroll transformation. J. Chem. Phys. 117, 9215–9226 (2002).

    Article  ADS  CAS  Google Scholar 

  46. Knowles, P. J., Hampel, C. & Werner, H.-J. Coupled cluster theory for high spin, open shell reference wave functions. J. Chem. Phys. 99, 5219–5228 (1993).

    Article  ADS  CAS  Google Scholar 

  47. Reed, A. E., Curtiss, L. A. & Weinhold, F. Intermolecular interactions from a natural bond orbital, donor-acceptor viewpoint. Chem. Rev. 88, 899–926 (1988).

    Article  CAS  Google Scholar 

  48. Glendening, E. D., Landis, C. R. & Weinhold, F. NBO 7.0: new vistas in localized and delocalized chemical bonding theory. J. Comput. Chem. 40, 2234–2241 (2019).

    Article  CAS  PubMed  Google Scholar 

  49. Glendening, E. D. et al. NBO 7.0. Theoretical Chemistry Institute, Univ. Wisconsin (2018).

  50. Frisch, M. J. et al. Gaussian 16, revision A.03. Gaussian, Inc. (2016).

  51. Werner, H.-J. et al. The Molpro quantum chemistry package. J. Chem. Phys. 152, 144107 (2020).

    Article  ADS  CAS  PubMed  Google Scholar 

  52. Werner, H.-J. et al. MOLPRO, version 2021, a package of ab initio programs. https://www.molpro.net (2021).

  53. Pore, J. Nobelium and actinium coordination chemistry study with FIONA. Zenodo https://zenodo.org/records/14277708 (2024).

Download references

Acknowledgements

We gratefully acknowledge the operations staff of the 88-Inch Cyclotron. The work of J.L.P., J.M.G., J.A.G. and R.O. was supported in part by the US Department of Energy, Office of Science, Office of Nuclear Physics under contract no. DE-AC02-05CH11231 (LBNL). The work of J.L.P., J.M.G., J.K.G., M.M., Z.S. and D.K.S. was supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Heavy Element Chemistry Program under contract number DE-AC02-05CH11231 (LBNL). The University of Alabama work of D.A.D. and S.S. was supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Heavy Element Chemistry Program through grant no. DE-SC0018921. D.A.D. thanks the Robert Ramsay Fund at the University of Alabama. F.H.G. was supported through a LBNL Laboratory Directed Research and Development programme.

Author information

Author notes

  1. Fatima H. Garcia

    Present address: Department of Chemistry, Simon Fraser University, Burnaby, British Columbia, Canada

Authors and Affiliations

  1. Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA

    Jennifer L. Pore, Jacklyn M. Gates, Fatima H. Garcia, John A. Gooding & Rodney Orford

  2. Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA

    Jennifer L. Pore, Jacklyn M. Gates, John K. Gibson, Mallory McCarthy, Ziad Shafi & David K. Shuh

  3. Department of Chemistry and Biochemistry, The University of Alabama, Tuscaloosa, AL, USA

    David A. Dixon & Sarah Sprouse

  4. Department of Nuclear Engineering, University of California, Berkeley, Berkeley, CA, USA

    John A. Gooding & Mallory McCarthy

  5. Department of Chemistry, University of California, Berkeley, Berkeley, CA, USA

    Ziad Shafi

Authors
  1. Jennifer L. Pore
    View author publications

    Search author on:PubMed Google Scholar

  2. Jacklyn M. Gates
    View author publications

    Search author on:PubMed Google Scholar

  3. David A. Dixon
    View author publications

    Search author on:PubMed Google Scholar

  4. Fatima H. Garcia
    View author publications

    Search author on:PubMed Google Scholar

  5. John K. Gibson
    View author publications

    Search author on:PubMed Google Scholar

  6. John A. Gooding
    View author publications

    Search author on:PubMed Google Scholar

  7. Mallory McCarthy
    View author publications

    Search author on:PubMed Google Scholar

  8. Rodney Orford
    View author publications

    Search author on:PubMed Google Scholar

  9. Ziad Shafi
    View author publications

    Search author on:PubMed Google Scholar

  10. David K. Shuh
    View author publications

    Search author on:PubMed Google Scholar

  11. Sarah Sprouse
    View author publications

    Search author on:PubMed Google Scholar

Contributions

J.L.P., J.M.G., M.M., J.K.G. and D.A.D. conceived the study. J.L.P., J.M.G., F.H.G., M.M. and R.O. prepared the experiment. J.L.P., J.M.G., F.H.G., J.K.G., J.A.G., M.M., R.O., Z.S. and D.K.S. participated in the experimental measurements. J.L.P. analysed the experimental data. D.A.D. and S.S. performed the electronic structure calculations. J.L.P., J.M.G., D.A.D., J.K.G. and D.K.S. were responsible for the interpretation of the experimental results. J.L.P. wrote the paper. J.L.P., D.A.D. and S.S. prepared materials for the Supplementary Information. All authors reviewed and edited the paper.

Corresponding author

Correspondence to Jennifer L. Pore.

Ethics declarations

Competing interests

The authors declare no competing interests.

Peer review

Peer review information

Nature thanks Robert Eichler, Alexander Yakushev and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

Additional information

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

Supplementary information

Supplementary Information

This Supplementary Information file contains the following three sections: S1: Secondary production formation for Ac2+ and No2+ reactions with H2O; S2: Electronic structure calculations; S3: Residual Gas Analyzer Readings. It includes 16 Supplementary Figures, 12 Supplementary Tables, and additional references.

Rights and permissions

Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Pore, J.L., Gates, J.M., Dixon, D.A. et al. Direct identification of Ac and No molecules with an atom-at-a-time technique. Nature 644, 376–380 (2025). https://doi.org/10.1038/s41586-025-09342-y

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue date:

  • DOI: https://doi.org/10.1038/s41586-025-09342-y

Search

Advanced search

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