Heavy-element damage seeding in proteins under XFEL illumination

Passmore, S.K.; Sanders, A.L.; Martin, A.V.; Quiney, H.M.

doi:10.1107/S1600577525005934

Figure 7
Evolution of electron-ionization cascades under plasma conditions in a light-atom target. Each plot shows a cascade density initiated by a free electron of energy (a) 0.5 keV, (b) 2 keV and (c) 8.5 keV. Each cascade occurs during a full dynamical simulation of the C₆₁₃N₂₀₃O₁₈₅ target under the 15 fs FWHM 9 keV pulse, in equivalent simulation conditions to Fig. 6

, with the cascade initiated when the pulse first reaches the FWHM intensity (−7.5 fs). The right axis of each plot shows the density of the cascade, normalized to correspond to the number of electrons. Dashed horizontal lines correspond to the intensity-averaged electron count. The 500 eV cascade (oxygen Auger electron) deposits a small amount of energy quickly, while the 8.5 keV cascade (oxygen photoelectron) is largely outrun by the pulse. The 2 keV cascade is the most damaging, depositing its energy over a timescale similar to the 15 fs FWHM of the XFEL pulse. Each cascade was tracked by injecting a negligibly small electron density into the system at t = −7.5 fs. At late times, the cascade densities are reduced by recombination.

JOURNAL OF
SYNCHROTRON
RADIATION

ISSN: 1600-5775

Volume 32| Part 5| September 2025| Pages 1124-1142

https://doi.org/10.1107/S1600577525005934

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