Femtosecond Nonadiabatic Confinement of Molecular Dication Yield
Abstract
Doubly charged molecular cations often carry signatures of electronic correlation and electron-nuclear entanglement present in the parent cation. Here, we produce ethylene dications using a combination of an extreme ultraviolet pump and near-infrared probe pulses, observing a peak in the dication yield at a pump-probe delay of approximately 15 fs. Ab-initio calculations, which explicitly take into account coupled electron-nuclear dynamics induced by the pump and the multiphoton nature of the probe-induced ionization step, reproduced the observed delay in the yield. It originates from resonant enhancement of the multiphoton ionization of the electronically excited ethylene cation as the carbon-carbon double bond expands. However, this effect is tempered by rapid nonadiabatic relaxation of the excited ionic states. Our results suggest a general mechanism whereby ultrafast nonadiabatic relaxation of a molecular ion can compete with its strong-field ionization rate, confining the dication yield to a narrow temporal window of a few femtoseconds.
Keywords
Cite
@article{arxiv.2601.22750,
title = {Femtosecond Nonadiabatic Confinement of Molecular Dication Yield},
author = {Carlos Marante and Lina Fransén and Alexie Boyer and Vincent Loriot and Franck Lépine and Luca Argenti and Morgane Vacher and Saikat Nandi},
journal= {arXiv preprint arXiv:2601.22750},
year = {2026}
}