Nanometer sized superfluid helium droplets provide an ideal approach to synthesize and investigate exotic molecules or clusters at temperatures close to absolute zero. Electronic excitation and ionization of particles inside the droplets by the absorption of photons trigger various dynamical processes. In this project single atoms located inside helium droplets will be used to investigate these processes on femto- (10-15 s) and picosecond (10-12 s) time scales.
The questions to be addressed are: 1) Which dynamical processes are initiated by photoexcitation and what are their time scales? 2) How does electronic relaxation after photoexcitation proceed? 3) Are molecules consisting of excited atoms and helium atoms formed? 4) What is the influence of the quantum fluid environment on the generated photoelectrons and photoions?
To answer these questions, femtosecond laser pulses will be used at the Institute of Experimental Physics of Graz University of Technology. A first pulse triggers the dynamics and a second pulse probes the system after a controlled time delay. The detection of photoelectrons and photoions as function of the time-delay between the two pulses will provide information about the dynamics of the system.
The project enables the investigation of dynamics after photoexcitation and -ionization in more complex molecular aggregates solvated in a superfluid environment. In particular, the applicability of helium nanodroplets for the investigation of photoinduced processes in molecules of technological or biological relevance will be explored.