%0 Generic
%A Magunia, Alexander
%C Heidelberg
%D 2024
%F heidok:35166
%R 10.11588/heidok.00035166
%T Time-and-Energy–Resolved Electron Dynamics in Atoms  and Molecules with Intense Short-Wavelength Light
%U https://archiv.ub.uni-heidelberg.de/volltextserver/35166/
%X This thesis investigates the interaction of ultrashort, extreme-ultraviolet (XUV) and  soft x-ray laser pulses with atoms and molecules in the gas phase. In total, the  subject is explored from four different perspectives, which are all based on the short-  lived–coherent electronic responses to the laser pulses, and measured with transient  absorption spectroscopy. First, a theoretical study reveals how transient energy shifts  of electronic dressed states in atoms driven by an intense XUV Free-Electron Laser  (FEL) lead to temporal dipole phase shifts and absorption-line changes. Second,  a follow-up study investigates the electronic-population Rabi-cycles corresponding  to the absorption-line changes of the first study. A convolutional neural network  is employed to reconstruct the temporal population dynamics from the simulated  spectral absorption modifications. The inversion from an absorption to an emission  line is described and a potential experimental demonstration in helium is discussed.  Third, dense gas targets enable amplification of the otherwise improbable, non-linear  process of stimulated resonant inelastic x-ray scattering (RIXS), as well as x-ray FEL  propagation-based spatial-spectral reshaping. To this end, a new experimental setup is  built and utilized in an x-ray FEL driven RIXS experiment in dense neon gas. Fourth,  a novel experiment combining XUV pulses from high-order harmonic generation  (HHG) and XUV-FEL pulses is demonstrated by time-resolving a photochemical  reaction in molecular oxygen. An FEL pulse initiates coupled nuclear-electronic  dissociation pathways from molecular oxygen ions, which are time-resolved on femto-  and picosecond time scales by identifying the reaction products in the time-delayed  HHG absorption spectra. A FEL-photon-energy–resolved study of the fragments  is performed to compare findings from absorption spectroscopy with kinetic energy  release spectra recorded in parallel with a reaction microscope.