X-ray free-electron lasers (XFELs) have brought new ways to probe and manipulate atomic
and molecular dynamics with unprecedented spatial and temporal resolutions. A …

The ultrashort and intense pulses of X-rays produced at X-ray free electron lasers (XFELs)
have enabled unique experiments on the atomic level structure and dynamics of matter, with …

The Small Quantum Systems instrument is one of the six operating instruments of the
European XFEL, dedicated to the atomic, molecular and cluster physics communities. The …

A theoretical model for investigating the radiative transfer of an x-ray free electron laser
(XFEL) pulse is developed based on a one-dimensional radiative transfer equation. The …

Extremely high charge states of atoms and molecules can be created when they are
irradiated by intense x-ray pulses. At certain x-ray photon energies, electron ejection from …

Resonances between core-hole states have been long hypothesized to understand
nonlinear responses of atoms and molecules exposed to intense x-ray free-electron laser …

A set of electron time-of-flight spectrometers for high-resolution angle-resolved spectroscopy
was developed for the Small Quantum Systems (SQS) instrument at the SASE3 soft X-ray …

In hot dense plasmas, orbital delocalization and relocalization considerably influence the
ionization balance, equation of state and radiative properties of matter. A self-consistent …

Theoretical exploration of the population dynamics at fine-structure levels of Ar atoms
interacting with ultrafast ultraintense x-ray free electron laser (XFEL) pulses is conducted. A …

A universal mechanism of ultrafast 2-electron orbital swap is discovered through 2-photon
sequential double ionization of Li. After a 1s electron in Li is ionized by absorbing an …