From 8 microns to 8 kiloelectronvolt
Ultrashort light pulses provide unique experimental tools for studying rapidly evolving structure of matter. In the optical domain ultrafast lasers can be efficiently applied to map the time evolution of photo-induced chemical reactions, opening the new field of femtochemistry. The extension of ultrafast light sources towards shorter (XUV and X-ray) wavelengths allowed probing light-induced dynamics with nearly atomic spatial resolution, and enabled targeting a particular site in an extended system by element-specific inner shell excitations. Besides short (femtosecond) pulse duration, many of these applications require a combination of different wavelengths needed to trigger and to map a process of interest, and high light intensities capable of driving non-linear processes.
Here I will present an overview of our ongoing effort to study a broad range of ultrafast and intense light-matter interactions covering a span of wavelengths from the infrared to hard X-ray domain. This activity combines experiments using optical lasers and their high-order harmonics at the J.R. Macdonald Laboratory at KSU with measurements performed at accelerator-based free-electron laser facilities such as LCLS in Stanford and FLASH in Hamburg. Particular examples, which will be considered, include imaging of light-induced wave packets in simple molecules, femtosecond response of small atomic and molecular systems to intense X-ray light, and experiments on isolated gas-phase nanoparticles.