Fig. 5: Femtosecond control of core-exciton resonances by Coulomb screening.

a Top panels: time evolution of excited electrons (red circles) and holes (green circles) distributions at 5, 10, 20, and 30 fs following optical pumping with fluence of 21.7 mJ cm⁻². Bottom panel: Corresponding calculated XAS spectra at the Zn K-edge show spectral evolution due to dynamical Coulomb screening. b Computed XTA spectra at  20 fs for various pump fluences from 7.7 to 85.3 mJ cm⁻² (colored curves). The calculated XTA spectrum at 100 ps with an excitation density of 1.5 × 10²⁰ cm⁻³ is shown for reference (shaded gray). c, d Computed excited-state XAS spectra with the probe polarization in (c) (a, b)-plane and d along the c-axis of the ZnO lattice for different pump fluences (same color coding as in b). e Blue shift of the first peak energy in the XAS spectra as a function of pump fluence for different probe polarizations: (a, b)-plane (blue) and c-axis (red).