Inter-atomic correlated decay processes in doped helium nanodroplets – probing heterogeneous nanosystems with EUV radiation

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This research project mainly aims at studying inter-atomic correlated decay processes in pure and doped He nanodroplets in the extreme-ultraviolet (EUV) up to the X-ray spectral ranges using synchrotron and ultrashort laser radiation. Novel correlated decay processes will be identified and characterized, which arise from the particular electronic structure of He (two-electron system, high-lying excited states and high ionization energy), the quantum fluid nature of He nanodroplets (high mobility of localized excitations), many-body interactions (two and many-body interatomic energy and charge transfer), and exotic combinations of species in hetero-clusters (He, metals, organic molecules, shells of water molecules, etc.). This quest will lead us toward a deeper understanding of the fundamental aspects of superfluidity on the nanoscale, and elucidate the role of geometric effects (bulk vs. surface) in the photodynamics of heterogeneous nanostructures. In particular, generic photo-physical processes of nanometer-sized doped He nanodroplets such as nanosolvation of neutrals and cations vs. expulsion of excited species and anions will be elucidated. These studies will contribute to the understanding of radiation damage in tailored nano-systems and in organic materials, as well as provide concepts and reference data for interpreting recent and upcoming Free-electron laser (FEL) experiments. These goals will be pursued by systematically investigating various systems (pure and doped He nanodroplets of various sizes and composition, Ne clusters), using different experimental detection techniques such as photoelectron-photoion coincidence detection (PEPICO) technique with velocity-map imaging (VMI) capability and EUV and visible fluorescence detection method. This proposed experimental work will be carried out at various locations, e.g. the AMO beamline of ASTRID2 synchrotron radiation facility at Aarhus University, FEL at FLASH in Hamburg and Fermi@Elettra in Trieste.