Ultrafast Extreme Ultraviolet Laser Science

This research project aims at the first application of extreme ultraviolet (EUV) femtosecond (fs) spectroscopy to doped superfluid helium nanodroplets (HeN). Experiments, which will investigate processes with fs time resolution in an ultarcold (0.4 K) and superfluid environment, are planned to be accomplished at the Institute of Experimental Physics of Graz University of Technology. In order to acquire expertise in the sophisticated fields of ultrafast laser physics and high photon-energy spectroscopy by means of high harmonic generation (HHG), the applicant plans to spend a one-year research period at the Stanford University PULSE Institute (headed by Philip Bucksbaum), in the group of Markus Gühr. The collaboration is aiming at novel time-resolved investigations of photo-induced reaction dynamics. Femtosecond UV-pump/EUV-probe techniques will be used to investigate non-Born-Oppenheimer and catalytical processes in organometallic molecules, both in gas phase and isolated in a quantum cryogenic matrix. The novelty lies in the use of core electrons instead of valence electrons to study molecular dynamics. The research program in Stanford will provide the applicant with the necessary know-how in order to apply fs-EUV spectroscopy to cold aggregates and clusters produced and isolated in superfluid HeN. Upon his return to Graz the applicant will establish a new ultrafast laser system with HHG. He plans to build his habilitation at TUG on this new research branch. Continuing collaboration with Stanford will provide exchange of knowledge. Femtosecond laser spectroscopy is a powerful technique to study real-time dynamics in atoms, molecules, and clusters, as well as the dynamics of chemical reactions. The possibility of HHG expands the excitation wavelength to the vacuum UV and EUV and thus provides direct access to much deeper electron levels. These inner valence and core electrons essentially expand the experimenter's scope because they often contain structural, magnetic, or chemical information, which is supplemental to that obtained from valence electron spectroscopy. HeN are attracting significant interest from many scientific communities due to their unique properties. Acting as a cold, superfluid bath, providing confinement for single particle isolation, and very easy and versatile doping feasibilities make them ideal and least perturbing hosts for spectroscopic investigations. Helium nanodroplet isolation spectroscopy has therefore hugely expanded within the last two decades. Although both techniques have been exploited extensively, no fs-HHG experiment has been performed with doped HeN up to now. This project thus aims at a substantial expansion of spectroscopic techniques for dynamic investigations at ultralow temperatures.