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Attosecond coupled electron and nuclear dynamics in dissociative ionization of H2


The interaction of an extreme-ultraviolet attosecond pulse with a molecular system suddenly removes electrons, which can lead to significant changes in the chemical bonding and hence to rearrangements of the residual molecular cation. The timescales of the electronic and nuclear dynamics are usually very different, thus supporting separate treatment. However, when light nuclei are involved, as in most organic and biological molecules containing atomic hydrogen, the correlation between electronic and nuclear motion cannot be ignored. Using an advanced attosecond pump–probe spectroscopic method, we show that the coupling between electronic and nuclear motion in H2 leaves a clear trace in the phase of the entangled electron–nuclear wave packet. This requires us to re-evaluate the physical meaning of the measured phase, which depends on the energy distribution between electrons and nuclei. The conclusions are supported by ab initio calculations that explicitly account for the coupling between electronic and nuclear dynamics.

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Fig. 1: H2 dissociative photoionization.
Fig. 2: Cross-section and kinetic energy correlation diagrams.
Fig. 3: 3D nuclear–electron phase–time map.
Fig. 4: Relative molecular phases as a function of the photon energy.


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This work is supported by the European Research Council (ERC) advanced grants ERC-2012-ADG_20120216 and ERC with grant agreement 290853 XCHEM within the Seventh Framework Programme of the European Union. We also acknowledge the financial support from the Ministry of Economy and External Trade (MINECO) projects FIS2013-42002-R and FIS2016-77889-R, and the European COST Action XLIC CM1204, and the computer time from the Centro de Computación Científica-Universidad Autónoma de Madrid (CCC-UAM) and Marenostrum Supercomputer. A.P. acknowledges a Ramón y Cajal contract from the Ministerio de Economiía y Competitividad (Spain). F.M. acknowledges support from the ‘Severo Ochoa’ Programme for Centres of Excellence in R&D (MINECO, Grant SEV-2016-0686) and the ‘María de Maeztu’ Programme for Units of Excellence in R&D (MDM-2014-0377).

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L.C., J.V., L.P. and S.H. performed the experimental measurements. L.C. and J.V. performed the experimental data analysis. R.Y.B., A.P. and F.M. performed the theoretical calculations and analysis. L.C., J.V., M.L., C.C., R.B., A.P., F.M. and U.K. contributed to the data interpretation, scientific discussion and to the manuscript.

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Correspondence to L. Cattaneo.

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Supplementary Information

Supplemenatry Chapters 1–6, Supplementary Figures 1–8

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Cattaneo, L., Vos, J., Bello, R.Y. et al. Attosecond coupled electron and nuclear dynamics in dissociative ionization of H2. Nature Phys 14, 733–738 (2018).

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