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.

Understanding the quantum nature of low-energy C(3Pj) + He inelastic collisions


Inelastic collisions that occur between open-shell atoms and other atoms or molecules, and that promote a spin–orbit transition, involve multiple interaction potentials. They are non-adiabatic by nature and cannot be described within the Born–Oppenheimer approximation; in particular, their theoretical modelling becomes very challenging when the collision energies have values comparable to the spin–orbit splitting. Here we study inelastic collisions between carbon in its ground state C(3Pj=0) and helium atoms—at collision energies in the vicinity of spin–orbit excitation thresholds (~0.2 and 0.5 kJ mol−1)—that result in spin–orbit excitation to C(3Pj=1) and C(3Pj=2). State-to-state integral cross-sections are obtained from crossed-beam experiments with a beam source that provides an almost pure beam of C(3Pj=0) . We observe very good agreement between experimental and theoretical results (acquired using newly calculated potential energy curves), which validates our characterization of the quantum dynamical resonances that are observed. Rate coefficients at very low temperatures suitable for chemical modelling of the interstellar medium are also calculated.

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

Fig. 1: Comparison of experimental and theoretical cross-sections for C(3P0) + He → C(3P1) + He inelastic collisions.
Fig. 2: Comparison of experimental and theoretical cross-sections for C(3P0) + He → C(3P2) + He inelastic collisions.
Fig. 3: Adiabatic bender curves with total angular momentum J = 4 and 5 that correlate with the C(3P1) state.


  1. Phillips, T. G. & Huggins, P. J. Abundances of atomic carbon (C I) in dense interstellar clouds. Astrophys. J. 251, 533–540 (1981).

    Article  CAS  Google Scholar 

  2. Zmuidzinas, J., Betz, A. L., Boreiko, R. T. & Goldhaber, D. M. Neutral atomic carbon in dense molecular clouds. Astrophys. J. 335, 774–785 (1988).

    Article  CAS  Google Scholar 

  3. Herbst, E. & Yates, J. T. Jr Introduction: Astrochemistry. Chem. Rev. 113, 8707–8709 (2013).

    Article  CAS  Google Scholar 

  4. Tanaka, K., Oka, T., Matsumura, S., Nagai, M. & Kamagai, K. High atomic carbon abundance in molecular clouds in the galactic center region. Astrophys. J. Lett. 743, L39 (2011).

    Article  Google Scholar 

  5. Wiese, W. L., Fuhr, J. R. & Deters, T. M. Atomic transition probabilities of carbon, nitrogen and oxygen. A critical data compilation. J. Phys. Chem. Ref. Data, Monograph 7 (1996).

  6. Stark, A. A. et al First detection of 492 GHz [C I] emission from the large Magellanic cloud. Astrophys. J. 480, L59–L62 (1997).

    Article  CAS  Google Scholar 

  7. Geppert, W. D. et al Combined crossed-beam studies of C(3Pj) + C2H4 → C3H3+H reaction dynamics between 0.49 and 30.8 kJ mol–1. J. Chem. Phys. 119, 10607–10617 (2003).

    Article  CAS  Google Scholar 

  8. Kaiser, R. I., Nguyen, T. L., Mebel, A. M. & Lee, Y. T. Stripping dynamics in the reactions of electronically excited carbon atoms, C(1D), with ethylene and propylene—production of propargyl and methylpropargyl radicals. J. Chem. Phys. 116, 1318–1324 (2002).

    Article  CAS  Google Scholar 

  9. Leonori, F. et al Unraveling the dynamics of the C(3P,1D) + C2H2 reactions by the crossed molecular beam scattering technique. J. Phys. Chem. A 112, 1363–1379 (2008).

    Article  CAS  Google Scholar 

  10. Chin, C.-H., Chen, W.-K., Huang, W.-J., Lin, Y.-C. & Lee, S.-H. Exploring the dynamics of reaction C(3P) + C2H4 with crossed beam/photoionization experiments and quantum chemical calculations. J. Phys. Chem. A 116, 7615–7622 (2012).

    Article  CAS  Google Scholar 

  11. Even, U. The Even–Lavie valve as a source for high intensity supersonic beam. EPJ Tech. Instrum. 2, 17 (2015).

    Article  Google Scholar 

  12. Jankunas, J., Reisyan, K. S. & Osterwalder, A. Preparation of state purified beams of He, Ne, C, N, and O atoms. J. Chem. Phys. 142, 104311 (2015).

    Article  Google Scholar 

  13. Le Picard, S. D. et al Experimental and theoretical study of intramultiplet transitions in collisions of C(3P) and Si(3P) with He. J. Chem. Phys. 117, 10109–10120 (2002).

    Article  Google Scholar 

  14. Pouilly, B., Orlikowski, T. & Alexander, M. H. Fully ab initio dynamics of fine-structure-changing transitions in collisions of Mg(3s3p 3P) with He. J. Phys. B18, 1953–1967 (1985).

    Article  CAS  Google Scholar 

  15. Alexander, M. H. et al. HIBRIDON package (College Park, MD: University of Maryland at College Park, 2011).

  16. Gubbels, K. B. et al Resonances in rotationally inelastic scattering of OH(X2Π) with helium and neon. J. Chem. Phys. 136, 144308–144313 (2012).

    Article  Google Scholar 

  17. Colbert, D. T. & Miller, W. H. A novel discrete variable representation for quantum mechanical reactive scattering via the S‐matrix Kohn method. J. Chem. Phys. 96, 1982–1991 (1992).

    Article  CAS  Google Scholar 

  18. Bergeat, A., Onvlee, J., Naulin, C., van der Avoird, A. & Costes, M. Quantum dynamical resonances in low-energy CO(j=0)+He inelastic collisions. Nat. Chem. 7, 349–353 (2015).

    Article  CAS  Google Scholar 

  19. Costes, M. & Naulin, C. Observation of quantum dynamical resonances in near cold inelastic collisions of astrophysical molecules. Chem. Sci. 7, 2462–2469 (2016).

    Article  CAS  Google Scholar 

  20. Pentlehner, D. et al Rapidly pulsed helium droplet source. Rev. Sci. Instrum. 80, 043302 (2009).

    Article  Google Scholar 

  21. Naulin, C. & Costes, M. Experimental search for scattering resonances in near cold molecular collisions. Int. Rev. Phys. Chem. 33, 427–446 (2014).

    Article  CAS  Google Scholar 

  22. Knowles, P. J., Hampel, C. & Werner, H.-J. Coupled cluster theory for high spin, open shell reference wave functions. J. Chem. Phys. 99, 5219–5227 (1993); erratum: 112, 3106–3107 (2000).

    Article  CAS  Google Scholar 

Download references


A.B., M.C., F.L., S.B.M. and C.N. acknowledge financial support from the Programme National ‘Physique et Chimie du Milieu Interstellaire’ (PCMI) of CNRS/INSU with INC/INP, co-funded by CEA and CNES, and the Agence Nationale de la Recherche, contract Hydrides (ANR-12-B505-0011-02). J.K. and F.L. acknowledge financial support from the US National Science Foundation grant no. CHE-1565872. The authors thank N. Lavie for constructing the DBD pulsed valve source, and M. Alexander for support and discussions about the quantum nature of resonances.

Author information

Authors and Affiliations



A.B., S.C., M.C., S.B.M. and C.N. carried out the experimental measurements and data analysis, with the contribution of U.E. for the development of the carbon source. J.K. and F.L. performed the theoretical calculations. All authors discussed the results and contributed to the manuscript.

Corresponding authors

Correspondence to Astrid Bergeat or François Lique.

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

Supplementary Methods, Figures 1–7 and Table 1

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Bergeat, A., Chefdeville, S., Costes, M. et al. Understanding the quantum nature of low-energy C(3Pj) + He inelastic collisions. Nature Chem 10, 519–522 (2018).

Download citation

  • Received:

  • Accepted:

  • 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