ECAMP 15

In recent years, my group explores intramolecular and intermolecular charge-transfer mechanisms in various ionization and neutralization processes.[1,2] Here, I will present ultrafast EUV pump – EUV probe studies of the $(CO_2)_2^+$ dynamics that we initiated by photoionization of neutral carbon dioxide dimers and probed by Coulomb explosion imaging as a function of the pump-probe time delay.[3] By comparing the experimental data with AIMD simulations we revealed unexpected asymmetric structural rearrangement from the slipped-parallel (C2h) geometry of the neutral $CO_2$ dimer towards a T-shaped (C2v) structure on the ~100 fs timescale. These results are surprising because of the most stable slipped-parallel (C2h) structure of the ionic dimer. I will also show that excited states of the ionized $CO_2$ dimer can exhibit formation of a $CO_3$ moiety in the $C_2O_4^+$ complex that can persist even after a suitably time-delayed second photoionization in a metastable $C_2O_4^{2+}$ dication. Our results suggest that charge asymmetry plays an important role in the ionization-induced dynamics in such dimers that are present in $CO_2$ rich environments, as well as in other symmetric dimer and cluster systems.
References
[1] K. Gope, et al., An “inverse” harpoon mechanism, Science Advances,8, 39 (2022)
[2] A. Bogot, et al., The mutual neutralization of hydronium and hydroxide, Science, 383,285 (2024)
[3] E. Livshits, et al., Symmetry-breaking dynamics of a photoionized carbon dioxide dimer, Nature Communications, 6322 (2024)