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Abstract

The observation of strong-field dynamics in atoms and molecules on ultra short timescales has been of high interest for a long time. In recent years the investigation of inner-shell electron dynamics became possible when strong ultrashort lasers in the extreme ultra violet (XUV) became reality in the form of free electron lasers (FEL). They allow for example the observation of charge transfer processes in molecules. In this spirit a measurement campaign was performed at FLASH (DESY), to investigate such phenomena at halogenated hydrocarbon molecules. This thesis describes the required further development of a transient absorption beam line and the new design of essential components with regards to experiments with corrosive targets and an FEL light source. An intensity dependent absorption measurement of a doubly excited state in helium was conducted as well. This can be considered an extension of prior work performed recently with near infrared and visible (VIS) strongfield modification of XUV absorption from lab-based HHG light source. The measurement described in this work investigates XUV strong-field modification of XUV absorption with partially coherent FEL light.