Joachim Ullrich

Title

Free-Electron Lasers: New Frontiers in Atomic and Molecular Research... And Beyond

Abstract

Free Electron Lasers (FEL) are innovative, accelerator-driven light sources that now have been demonstrated to deliver, for the first time, intense coherent light in a wavelength regime from tens of nanometers down to even one Ångström. Pulse intensities surpass those of synchrotrons by a factor of one billion and the light flashes, with a duration of less than ten femtoseconds (1 fs = 10-15 s), are more than thousand times shorter than achievable up to now. Thus, FELs penetrate a terra incognita in light-matter interaction opening a new chapter in science throughout all disciplines, in physics, material science, chemistry or biology.

The lecture will highlight the working principles of FELs and the performance of the first machines operational worldwide. Pioneering experiments in atomic, molecular and cluster physics are presented. They explore, for example, the interaction of photons with hot stellar as well as cold interstellar matter, characterize nonlinear processes in atoms or trace ultrafast motion like isomerisation in molecules. At X-ray energies attosecond multiple ionization dynamics in atoms was investigated, the correlated motion of the lattice and electrons in the conduction band of semiconductors was traced and nano-particles, clusters or nano-plasmas were coherently imaged. Finally, if time allows, the rich future possibilities are envisioned.