1. Femtosecond Symmetry Breaking and Coherent Relaxation of Methane Cations at the Carbon K-Edge
- Author
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Ridente, Enrico, Hait, Diptarka, Haugen, Eric A., Ross, Andrew D., Neumark, Daniel M., Head-Gordon, Martin, and Leone, Stephen R.
- Subjects
Physics - Chemical Physics ,Quantum Physics - Abstract
Understanding the relaxation pathways of photoexcited molecules is essential to gain atomistic level insight into photochemistry. Herein, we perform a time-resolved study of ultrafast molecular symmetry breaking via geometric relaxation (Jahn-Teller distortion) on the methane cation. Attosecond transient absorption spectroscopy with soft X-rays at the carbon K-edge reveals that the distortion occurs within $10\pm 2$ femtoseconds after few-femtosecond strong-field ionization of methane. The distortion activates coherent oscillations in the scissoring vibrational mode of the symmetry broken cation, which are detected in the X-ray signal. These oscillations are damped within $58\pm13$ femtoseconds, as vibrational coherence is lost with the energy redistributing into lower-frequency vibrational modes. This study completely reconstructs the molecular relaxation dynamics of this prototypical example and opens new avenues for exploring complex systems.
- Published
- 2022
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