Towards the investigation of ultrafast dynamics in chiral systems using free-electron lasers

Chiral molecules are life’s building blocks, making the study of their ultrafast processes a pursuit across various fundamental research fields. The results presented in this dissertation contain methodological, technical and scientific advancements that pave the way for future time-resolved, site-specific investigations into chiral photochemistry of randomly orientated molecules, using photoelectron circular dichroism and free-electron lasers. The high-repetitionrate free-electron lasers EuXFEL and FLASH2 will soon deliver undulatorbased circularly polarized pulses, opening new avenues for chiral studies. The EuXFEL’s instrumentation and applicability for chiral studies are presented based on the first performed experiments at the SQS endstation. The ultrafast spectroscopy technique of velocity map imaging and its suitability to measure the angular distribution of photoelectrons and ions in experiments targeting ultrafast dynamics is presented in detail. The double-sided velocity map imaging spectrometer, which was built and commissioned in the frame of this work, is presented, including technical details, and its simulated and experimentally retrieved performance. Inside into a performed study combining free-electron lasers and double-sided velocity map imaging spectroscopy, in the light of chiral perspectives, is given via the performed and here-presented experiment at FLASH1. Here, highly intense XUV pulses 63 eV and 75 eV, addressing the neutral and singly charged iodine 4d edge respectively, were used to probe the optical laser-induced fragmentation of the prototypical chiral molecule 1-iodo-2-methyl-butane (C5H11I) in a pump-probe scheme using 267nm and 800nm pulses. For charged Coulombic interaction of dissociating photofragments, the optical-laser-pump FEL-probe scans revealed that the molecule dissociates significantly slower with an 800nm pump than with a 267nm pump. The results show substantial wavelength and intensity dependence for the dissociation dynamics of this prototypical chiral molecule. In addition, electron-ion partial covariance imaging was demonstrated and enabled isolating the I 4d atomic and molecular levels. The outcomes of this dissertation provide a basis for future time-resolving investigations of chiral systems using free-electron lasers.