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.

Vibrational excitation through tug-of-war inelastic collisions

Abstract

Vibrationally inelastic scattering is a fundamental collision process that converts some of the kinetic energy of the colliding partners into vibrational excitation1,2. The conventional wisdom is that collisions with high impact parameters (where the partners only ‘graze’ each other) are forward scattered and essentially elastic, whereas collisions with low impact parameters transfer a large amount of energy into vibrations and are mainly back scattered3. Here we report experimental observations of exactly the opposite behaviour for the simplest and most studied of all neutral–neutral collisions: we find that the inelastic scattering process H + D2(v = 0, j = 0, 2) → H + D2(v′ = 3, j′ = 0, 2, 4, 6, 8) leads dominantly to forward scattering (v and j respectively refer to the vibrational and rotational quantum numbers of the D2 molecule). Quasi-classical trajectory calculations show that the vibrational excitation is caused by extension, not compression, of the D–D bond through interaction with the passing H atom. However, the H–D interaction never becomes strong enough for capture of the H atom before it departs with diminished kinetic energy; that is, the inelastic scattering process is essentially a frustrated reaction in which the collision typically excites the outward-going half of the H–D–D symmetric stretch before the H–D2 complex dissociates. We suggest that this ‘tug of war’ between H and D2 is a new mechanism for vibrational excitation that should play a role in all neutral–neutral collisions where strong attraction can develop between the collision partners.

Your institute does not have access to this article

Access options

Buy article

Get time limited or full article access on ReadCube.

$32.00

All prices are NET prices.

Figure 1: Products of inelastic H + D 2 collisions are mostly forward scattered.
Figure 2: Impact parameter is linearly correlated with deflection angle.
Figure 3: Snapshots from a representative forward-scattered trajectory.

References

  1. Faubel, M. Vibrational and rotational excitation in molecular collisions. Adv. At. Mol. Phys. 19, 345–394 (1983)

    CAS  ADS  Article  Google Scholar 

  2. Krajnovich, D. J., Parmenter, C. S. & Catlett, D. L. State-to-state vibrational transfer in atom-molecule collisions. Beams vs. bulbs. Chem. Rev. 87, 237–288 (1987)

    CAS  Article  Google Scholar 

  3. Levine, R. D. Molecular Reaction Dynamics 376 (Cambridge Univ. Press, Cambridge, UK, 2005)

    Book  Google Scholar 

  4. Miller, W. H. The semiclassical nature of atomic and molecular collisions. Acc. Chem. Res. 4, 161–167 (1971)

    CAS  Article  Google Scholar 

  5. McBane, G. C., Kable, S. H., Houston, P. L. & Schatz, G. C. Collisional excitation of CO by 2.3 eV H atoms. J. Chem. Phys. 94, 1141–1149 (1991)

    CAS  ADS  Article  Google Scholar 

  6. Kreutz, T. G. & Flynn, G. W. Analysis of translational, rotational, and vibrational energy transfer in collisions between CO2 and hot hydrogen atoms: The three-dimensional “breathing” ellipsoid model. J. Chem. Phys. 93, 452–465 (1990)

    CAS  ADS  Article  Google Scholar 

  7. Wight, C. A., Donaldson, D. J. & Leone, S. R. A two-laser pulse-and-probe study of T-R, V energy transfer collisions of H + NO at 0.95 and 2.2 eV. J. Chem. Phys. 83, 660–667 (1985)

    CAS  ADS  Article  Google Scholar 

  8. Rapp, D. & Kassal, T. The theory of vibrational energy transfer between simple molecules in nonreactive collisions. Chem. Rev. 69, 61–102 (1969)

    CAS  Article  Google Scholar 

  9. Koszinowski, K., Goldberg, N. T., Pomerantz, A. E. & Zare, R. N. Construction and calibration of an instrument for three-dimensional ion imaging. J. Chem. Phys. 125, –133503 (2006)

    ADS  Article  Google Scholar 

  10. Goldberg, N. T., Koszinowski, K., Pomerantz, A. E. & Zare, R. N. Doppler-free ion imaging of hydrogen molecules produced in bimolecular reactions. Chem. Phys. Lett. 433, 439–443 (2007)

    CAS  ADS  Article  Google Scholar 

  11. Koszinowski, K. et al. Differential cross section for the H+D2→HD(v′ = 1, j′ = 2, 6, 10)+D reaction as a function of collision energy. J. Chem. Phys. 127, –124315 (2007)

    ADS  Article  Google Scholar 

  12. Shafer, N. E., Orr-Ewing, A. J., Simpson, W. R., Xu, H. & Zare, R. N. State-to-state differential cross sections from photoinitiated bulb reactions. Chem. Phys. Lett. 212, 155–162 (1993)

    CAS  ADS  Article  Google Scholar 

  13. Boothroyd, A. I., Keogh, W. J., Martin, P. G. & Peterson, M. R. A refined H3 potential energy surface. J. Chem. Phys. 104, 7139–7152 (1996)

    CAS  ADS  Article  Google Scholar 

  14. Wrede, E. et al. The dynamics of the hydrogen exchange reaction at 2.20 eV collision energy: Comparison of experimental and theoretical differential cross sections. J. Chem. Phys. 110, 9971–9981 (1999)

    CAS  ADS  Article  Google Scholar 

  15. Greaves, S. J., Murdock, D., Wrede, E. & Althorpe, S. C. New, unexpected, and dominant mechanisms in the hydrogen exchange reaction. J. Chem. Phys. 128, 164306 (2008)

    ADS  Article  Google Scholar 

  16. Greaves, S. J., Murdock, D. & Wrede, E. A quasi-classical trajectory study of the time-delayed forward scattering in the hydrogen exchange reaction. J. Chem. Phys. 128, 164307 (2008)

    ADS  Article  Google Scholar 

  17. Fernández-Alonso, F. et al. Evidence for scattering resonances in the H+D2 reaction. Angew. Chem. Int. Ed. 39, 2748–2752 (2000)

    Article  Google Scholar 

  18. Allison, T. C., Friedman, R. S., Kaufman, D. J. & Truhlar, D. G. Analysis of the resonance in H+D2→HD(v′ = 3)+D. Chem. Phys. Lett. 327, 439–445 (2000)

    CAS  ADS  Article  Google Scholar 

  19. Althorpe, S. C. et al. Observation and interpretation of a time-delayed mechanism in the hydrogen exchange reaction. Nature 416, 67–70 (2002)

    CAS  ADS  Article  Google Scholar 

  20. Fernández-Alonso, F. & Zare, R. N. Scattering resonances in the simplest chemical reaction. Annu. Rev. Phys. Chem. 53, 67–99 (2002)

    ADS  Article  Google Scholar 

  21. Ayers, J. D. et al. Measurement of the cross section for H+D2→HD(v′ = 3, j′ = 0)+D as a function of angle and energy. J. Chem. Phys. 119, 4662–4670 (2003)

    CAS  ADS  Article  Google Scholar 

  22. Aoiz, F. J., Bañares, L. & Herrero, V. J. The H + H2 reactive system. Progress in the study of the dynamics of the simplest reaction. Int. Rev. Phys. Chem. 24, 119–190 (2005)

    CAS  Article  Google Scholar 

  23. Monks, P. D. D., Connor, J. N. L. & Althorpe, S. C. Theory of time-dependent reactive scattering: Cumulative time-evolving differential cross sections and nearside-farside analyses of time-dependent scattering amplitudes for the H+D2→HD+D reaction. J. Phys. Chem. A 110, 741–748 (2006)

    CAS  Article  Google Scholar 

  24. Monks, P. D. D., Connor, J. N. L. & Althorpe, S. C. Nearside-farside and local angular momentum analyses of time-independent scattering amplitudes for the H+D2(v i = 0, j i = 0)→HD(v f = 3, j f = 0)+D reaction. J. Phys. Chem. A 111, 10302–10312 (2007)

    CAS  Article  Google Scholar 

  25. Goldberg, N. T., Zhang, J., Miller, D. J. & Zare, R. N. Corroboration of theory for H+D2→D+HD(v′ = 3,j′ = 0) reactive scattering dynamics. J. Phys. Chem. A 10.1021/jp801187p (in the press)

  26. Giese, C. F. & Gentry, W. R. Classical trajectory treatment of inelastic scattering in collisions of H+ with H2, HD, and D2 . Phys. Rev. A 10, 2156–2173 (1974)

    CAS  ADS  Article  Google Scholar 

  27. Hege, U. & Linder, F. Vibrationally inelastic scattering of H- ions from H2, N2, O2 and CO2 . Z. Phys. A 320, 95–104 (1985)

    CAS  ADS  Article  Google Scholar 

  28. Osborn, M. K. & Smith, I. W. M. A quasiclassical trajectory study of vibrational energy transfer in collisions involving intermolecular attraction of moderate strength. Chem. Phys. 91, 13–26 (1984)

    CAS  Article  Google Scholar 

Download references

Acknowledgements

The Stanford team gratefully acknowledges support by the US National Science Foundation under grant NSF CHE 0650414. S.J.G. is supported by the EPSRC LASER Portfolio Partnership grant GR/S71750/01.

Author Contributions N.T.G. designed and performed the experiments with the help of J.Z. and D.J.M., analysed the experimental data, and assisted with the manuscript. S.J.G and E.W. performed quasi-classical trajectory calculations, formulated the mechanism, and prepared figures and movies. R.N.Z. wrote the manuscript. All authors discussed the results and commented on the manuscript.

Author information

Authors and Affiliations

Authors

Corresponding author

Correspondence to Richard N. Zare.

Supplementary information

Supplementary information

The file contains Supplementary Figures 1-7 with Legends. The file includes an overview of the QCT method and the BKMP2 PES, followed by impact-parameter/deflection-angle correlation diagrams indicating those trajectories for which movies are made available in the Supplementary Information. Measured DCSs for the complementary reactive HD(v?=3, j?=0) channel are compared with fully QM calculations. (PDF 631 kb)

Supplementary information

The file contains Supplementary Videos 1-6. The file includes QCT movies for six representative trajectories leading to D2(v?=3, j?=0) products. In each case the D-D bond is not compressed by the incoming H atom; instead, it is extended. In some cases it is pulled out whereas in others it is stabilized at the turning point. (PPT 4558 kb)

Supplementary information

The file contains Supplementary Videos 7-10. The file includes QCT movies for four representative trajectories leading to D2(v?=3, j?=4) products. The same mechanism is operative for this product state: the D-D bond is not compressed by the incoming H atom; instead it is extended. In some cases it is pulled out whereas in others it is stabilized at the turning point. (PPT 4570 kb)

PowerPoint slides

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Greaves, S., Wrede, E., Goldberg, N. et al. Vibrational excitation through tug-of-war inelastic collisions. Nature 454, 88–91 (2008). https://doi.org/10.1038/nature07079

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nature07079

Further reading

Comments

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.

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