Ultrafast dynamics of Double-Core-Hole

This PhD thesis focuses on the ultrafast dynamics of double-core-hole (DCH) states in atoms and molecules using synchrotron radiation and free-electron lasers (XFELs). DCH states, created through single-photon or sequential two-photon ionization, provide enhanced chemical sensitivity and unique insights into electron correlation and ultrafast nuclear dynamics. Using high-resolution electron spectroscopy, this research investigates DCH formation and decay in neon (Ne), water (H₂O), and methyl fluoride (CH₃F). The experimental work was conducted at the SOLEIL synchrotron and the European XFEL, leveraging the advantages of these advanced light sources. The findings contribute to the understanding of electron dynamics, chemical bonding, and potential applications in spectroscopy and radiation damage studies.