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Physical chemistry, chemical physics 24(44), 27121 - 27127 (2022). doi:10.1039/D2CP02408J special issue: "Ions, electrons, coincidences and dynamics: Festschrift for John H.D. Eland", During the last decade, X-ray free-electron lasers (XFELs) have enabled the study of light–matter interaction under extreme conditions. Atoms which are subject to XFEL radiation are charged by a complex interplay of (several subsequent) photoionization events and electronic decay processes within a few femtoseconds. The interaction with molecules is even more intriguing, since intricate nuclear dynamics occur as the molecules start to dissociate during the charge-up process. Here, we demonstrate that by analyzing photoelectron angular emission distributions and kinetic energy release of charge states of ionic molecular fragments, we can obtain a detailed understanding of the charge-up and fragmentation dynamics. Our novel approach allows for gathering such information without the need of complex ab initio modeling. As an example, we provide a detailed view on the processes happening on a femtosecond time scale in oxygen molecules exposed to intense XFEL pulses., Published by RSC Publ., Cambridge

This contribution presents the laser infrastructure concept of the Soft X-ray Port (SXP) instrument at the European X-ray Free Electron Laser (XFEL) for day one operation. This scientific platform is conceived as an open port complementing the scientific scope of the other two, already operating baseline instruments at the SASE 3 soft x-ray undulator focusing on atomic, molecular and non-linear optical (SQS) as well as condensed matter physics (SCS). The main driving force behind SXP originates from the time-resolved X-ray photo-electron spectroscopy community contemplating key questions in the dynamics of materials science at interfaces. Nonetheless, proposals to investigate high-valent metal intermediates in biological and inorganic catalysts for chemical bond activation by means of fluorescence spectroscopy as well as research on highly charged ions in the light of astrophysics are also pursued. The outstanding capabilities of the European XFEL pave the way for ultrafast pump-probe investigations at the SXP instrument combining intense and tunable soft X-rays with versatile optical laser capabilities, which are provided by two synchronized femtosecond laser systems, whose wavelength ranges can be extended into the infrared as well as extreme ultraviolet region.