The Physics department colloquia are usually on Friday afternoons at 3 pm in Room 135. Coffee and cookies are served at 2:45 pm in the same room. Anyone is welcome.

Real-time Imaging of Light-induced Reactions: From Strong-field Physics to Ultrafast Photochemistry
Dr. Artem Rudenko, Assistant Professor, Dept. of Physics (James Macdonald Lab), Kansas State University

Over the last thirty years we have witnessed rapid development of intense short-pulsed coherent radiation sources, such as femtosecond optical and infrared lasers, their higher-order harmonics in the extreme ultra-violet (EUV) domain, and EUV/X-ray free-electron lasers. These novel tools opened up a variety of exciting possibilities to visualize structure of matter, and to trace its dynamical evolution of a length and time scales of single atom motion. In particular, significant advances had been made towards tracing photo-induced chemical reactions in real time, defining properties of molecular transition states and imaging nano-scale objects with nearly atomic resolution. Most of these measurements exploit the availability of ultrashort intense light bursts in a broad range of wavelengths, which allows one to initiate different types of dynamics (e.g., create decaying excited states of an atom, prepare a bound or continuum molecular wave packet, etc.), and then to obtain snapshots of the created transient structure faster than the latter evolves (the so-called “pump-probe” scheme). The success of this approach critically depends on our understanding of basic mechanisms of (often non-linear) light-matter interactions, starting from the electronic response of single atoms.

I will present an overview of the experimental program aimed to develop novel schemes of ultrafast time-resolved measurements, and to advance our knowledge on the interaction of atoms, molecules and nano-size particles with intense laser-like radiation of different wavelengths, focusing on the experiments employing coincidence ion and electron imaging techniques for taking snapshots of atomic and molecular structure. Examples will include measurements in optical, EUV and X-ray domains.