Bertold Krässig

TL;DR: The nature of the electronic response in a free atom to unprecedented high-intensity, short-wavelength, high-fluence radiation is revealed and successful modelling of X-ray/atom interactions using a straightforward rate equation approach augurs favourably for extension to complex systems.

TL;DR: The nonlinear absorption mechanisms of neon atoms to intense, femtosecond kilovolt x rays are investigated and the nonlinear direct two-photon ionization cross section is orders of magnitude higher than expected from previous calculations.

TL;DR: This work demonstrates the propensity of high-fluence, femtosecond x-ray pulses to alter the target within a single pulse, i.e., to unveil hidden resonances, by cracking open inner shells energetically inaccessible via single-photon absorption, and to consequently trigger damaging electron cascades at unexpectedly low photon energies.

TL;DR: The use of high repetition rate, short pulse lasers as pump sources will dramatically enhance the duty cycle and efficiency in data acquisition and hence capabilities for laser-pump/x-ray probe studies of ultrafast structural dynamics at synchrotron sources.

TL;DR: The measured asymmetries are in excellent agreement with theoretical calculations, which include interference between the electric-dipole and electric-quadrupole photoionization amplitudes.