Department of Physics and Astronomy, Northwestern University
Free-electron lasers are a new class of x-ray sources that deliver extremely intense, coherent x-ray flashes with femtosecond pulse length. The unprecedented brightness of these x-ray lasers opens the door for imaging transient states of matter and non-linear spectroscopy approaches for core-level states. After a short introduction to free-electron lasers, I will present selected science examples enabled by these sources. First, I will present opportunities in AMO and nanoscale physics arising from ultrafast imaging approaches. Single-shot imaging of individual superfluid helium nanodroplets allows the unambiguous identification of quantum vortices. Ultrafast scattering of highly excited nanoplasmas carries information about their transient electronic states. The combination of optical with x-ray lasers allows the investigation of dynamically evolving systems with femtosecond time and nanometer spatial resolution. I will finish my talk with current developments in the Argonne AMO group on multi-color and time-resolved x-ray spectroscopy approaches. I will conclude with some thoughts about where I see the field heading in the next years and what exciting opportunities can be envisioned.