The Photochemical Birth of the Hydrated Electron in Liquid Water

Fuente: arXiv
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Autores principales: Mirón, Gonzalo Díaz, Malosso, Cesare, Di Pino, Solana, Egan, Colin K., Dasgupta, Diganta, Mundy, Christopher J., Hassanali, Ali
Formato: Preprint
Publicado: 2025
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author Mirón, Gonzalo Díaz
Malosso, Cesare
Di Pino, Solana
Egan, Colin K.
Dasgupta, Diganta
Mundy, Christopher J.
Hassanali, Ali
author_facet Mirón, Gonzalo Díaz
Malosso, Cesare
Di Pino, Solana
Egan, Colin K.
Dasgupta, Diganta
Mundy, Christopher J.
Hassanali, Ali
contents The photophysics and photochemistry associated with irradiating UV light in liquid water is central to numerous physical, chemical and biological processes. One of the key events involved in this process is the generation of the hydrated electron. Despite long study from both experimental and theoretical fronts, a unified understanding of the underlying mechanisms associated with the generation of the solvated electron have remained elusive. Here, using excited-state molecular dynamics simulations of condensed phase photoexcited liquid water, we unravel the key sequence of chemical events leading to the creation of the hydrated electron on the excited state. The process begins through the excitation localized mostly on specific topological defects in the hydrogen-bond network of water which is subsequently followed by two main reaction pathways. The first, leads to the creation of a hydrogen atom culminating in non-radiative decay back to the ground-state within 100 femtoseconds. The second involves a proton coupled electron transfer, giving rise to the formation of the hydronium ion, hydroxyl radical and the hydrated excess electron on the excited-state. This process is facilitated by ultrafast coupled rotational and translational motions of water molecules leading to the formation of water mediated ion-radical pairs in the network. These species can survive on the picosecond timescale and ultimately modulate the emission of visible photons. All in all, our findings provide fresh perspectives into the interpretation of several independent time-dependent spectroscopies measured over the last decades, paving the way for new directions on both theoretical and experimental fronts.
format Preprint
id arxiv_https___arxiv_org_abs_2508_19702
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The Photochemical Birth of the Hydrated Electron in Liquid Water
Mirón, Gonzalo Díaz
Malosso, Cesare
Di Pino, Solana
Egan, Colin K.
Dasgupta, Diganta
Mundy, Christopher J.
Hassanali, Ali
Chemical Physics
Soft Condensed Matter
The photophysics and photochemistry associated with irradiating UV light in liquid water is central to numerous physical, chemical and biological processes. One of the key events involved in this process is the generation of the hydrated electron. Despite long study from both experimental and theoretical fronts, a unified understanding of the underlying mechanisms associated with the generation of the solvated electron have remained elusive. Here, using excited-state molecular dynamics simulations of condensed phase photoexcited liquid water, we unravel the key sequence of chemical events leading to the creation of the hydrated electron on the excited state. The process begins through the excitation localized mostly on specific topological defects in the hydrogen-bond network of water which is subsequently followed by two main reaction pathways. The first, leads to the creation of a hydrogen atom culminating in non-radiative decay back to the ground-state within 100 femtoseconds. The second involves a proton coupled electron transfer, giving rise to the formation of the hydronium ion, hydroxyl radical and the hydrated excess electron on the excited-state. This process is facilitated by ultrafast coupled rotational and translational motions of water molecules leading to the formation of water mediated ion-radical pairs in the network. These species can survive on the picosecond timescale and ultimately modulate the emission of visible photons. All in all, our findings provide fresh perspectives into the interpretation of several independent time-dependent spectroscopies measured over the last decades, paving the way for new directions on both theoretical and experimental fronts.
title The Photochemical Birth of the Hydrated Electron in Liquid Water
topic Chemical Physics
Soft Condensed Matter
url https://arxiv.org/abs/2508.19702