Fig. 5. Calculated transient form factors at the resonance.

At 530 eV, resonance-mediated pathways induced by a broadband XFEL pulse lead to one or more cascades of core excitation and Auger decay in oxygen atoms. These processes induce rapid changes in the electronic configurations, as well as scattering amplitudes, since the atomic form factor is sensitive to electronic configurations near resonances. The gray dots indicate the absolute values of the complex form factor in the forward direction, $\mid f\left(Q=0\right)\mid$, at 530 eV. The color of the depicted electronic states corresponds to the color of the calculated form factors.