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.