Atomic memory in molecular charge evolution in deep inner-shell Auger cascades.
6 affiliations
- 1Laboratoire de Chimie Physique-Matière et Rayonnement
- 2L’Orme des Merisiers
- 3Rostov State Transport University
- 4Department of Physics and Astronomy
- 5University of Turku
- 6Institute of Physics, University of Tartu, W. Ostwaldi 1, Tartu, Estonia, EE-50411
Abstract
A single low-keV X-ray photon can strip a molecule of more than ten electrons. Deep inner-shell ionization of heavy atoms, including those incorporated into radiosensitizers in emerging cancer therapies, initiates an Auger cascade that rapidly builds up high charge and can drive extensive fragmentation. How this charge accumulates, not the total energy deposited alone, governs the molecular response to irradiation. Yet cascade-driven charge buildup is neglected in current radiation-damage and dosimetry models because complex Auger cascades remain poorly understood, and tracing how this initially local atomic process develops into an extended molecular response remains challenging. We demonstrate that the total charge produced by an Auger cascade is already encoded in the first Auger decay step, which can be described using existing atomic data. State-selective Auger-electron–ion coincidence measurements on atomic xenon resolve this earliest branching and reveal markedly different final charge distributions, with mean charges ranging from +4 to +11 depending on the first Auger decay channel. In molecules, the later cascade is strongly modified by the surrounding valence-electron environment. Measurements on molecular iodine show substantially enhanced charge buildup, which is captured by an “ideal electron-reservoir model” representing how sustained access to valence electrons increases both the final charge and electron emission. Together, these results connect the intrinsically atomic first Auger decay step to the final molecular charge buildup and provide a route to include cascade-driven charging in predictive descriptions of X-ray damage, from structural biology to emerging Auger therapies.
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BibTeX
@misc{travnikova2026atomic,
title = {{Atomic memory in molecular charge evolution in deep inner-shell Auger cascades.}},
author = {O. Travnikova and A. P. Chaynikov and H. Hartikainen and K.–I. Pusa and M. Berholts and D. Céolin and T. Marchenko and I. Ismail and A.G. Kochur and A.I. Dudenko and M. Simon and E. Kukk and Oksana TRAVNIKOVA},
howpublished = {ChemRxiv},
year = {2026},
month = oct,
doi = {10.26434/chemrxiv.15010098/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15010098/v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Atomic memory in molecular charge evolution in deep inner-shell Auger cascades.
AU - O. Travnikova
AU - A. P. Chaynikov
AU - H. Hartikainen
AU - K.–I. Pusa
AU - M. Berholts
AU - D. Céolin
AU - T. Marchenko
AU - I. Ismail
AU - A.G. Kochur
AU - A.I. Dudenko
AU - M. Simon
AU - E. Kukk
AU - Oksana TRAVNIKOVA
PY - 2026
DA - 2026/10/08
PB - ChemRxiv
DO - 10.26434/chemrxiv.15010098/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15010098/v1
AB - A single low-keV X-ray photon can strip a molecule of more than ten electrons. Deep inner-shell ionization of heavy atoms, including those incorporated into radiosensitizers in emerging cancer therapies, initiates an Auger cascade that rapidly builds up high charge and can drive extensive fragmentation. How this charge accumulates, not the total energy deposited alone, governs the molecular response to irradiation. Yet cascade-driven charge buildup is neglected in current radiation-damage and dosimetry models because complex Auger cascades remain poorly understood, and tracing how this initially local atomic process develops into an extended molecular response remains challenging. We demonstrate that the total charge produced by an Auger cascade is already encoded in the first Auger decay step, which can be described using existing atomic data. State-selective Auger-electron–ion coincidence measurements on atomic xenon resolve this earliest branching and reveal markedly different final charge distributions, with mean charges ranging from +4 to +11 depending on the first Auger decay channel. In molecules, the later cascade is strongly modified by the surrounding valence-electron environment. Measurements on molecular iodine show substantially enhanced charge buildup, which is captured by an “ideal electron-reservoir model” representing how sustained access to valence electrons increases both the final charge and electron emission. Together, these results connect the intrinsically atomic first Auger decay step to the final molecular charge buildup and provide a route to include cascade-driven charging in predictive descriptions of X-ray damage, from structural biology to emerging Auger therapies.
ER -