Fig. 4: Theoretical analysis of sulfur displacements as a function of pump probe delay.

a Average distance between sulfur atoms of a S–S bridge as a function of pump-probe time delay in thaumatin, predicted by the XMDYN molecular dynamics simulation. The red, green and blue curves represent the S–S distances for the experimental total nominal fluence (pump and probe combined), Ϝ_max = 7.0 × 10¹² photons µm⁻², Ϝ_med = 4.4 × 10¹² photons µm⁻² (64% of Ϝ_max) and Ϝ_low = 8.8 × 10¹¹ photons µm⁻² (13% of Ϝ_max), respectively, whereas the black curve with error bars represents the experimentally measured S–S separation with delay uncertainty and distance error included (see Supplementary Discussion). b Average distance between sulfur ions in a S–S bridge in lysozyme, as a function of pump-probe time delay, predicted by the hybrid continuum model. For direct comparison between the two models, the variations in the ionic charges in the hybrid model were matched to the corresponding XMDYN results. The good agreement between the two models confirms the importance of plasma electron screening and ion caging effects. The error bars of the experimental values correspond to the standard deviations of the XTCAV-derived time-delay values (x-axis) and give the standard deviation of the distribution (y-axis).