EUV photoionization of pure and doped He nanodroplets and Ne clusters

• Applicant: Professor Dr. Marcel Mudrich
• Subject Area: Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas ; Experimental Condensed Matter Physics ; Physical Chemistry of Molecules, Liquids and Interfaces, Biophysical Chemistry
• Term: from 2015 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 269369328

We propose to conduct a series of experiments on direct and indirect photoionization of helium (He) nanodroplets and on neon (Ne) clusters using EUV radiation at the synchrotron Elettra in Trieste, Italy. The goal is to explore and systematically characterize various aspects of the photodynamics of pure and doped He droplets and Ne clusters initiated by resonant excitation or ionization. He nanodroplets and Ne clusters are particularly suited for investigating fundamental aspects of light-matter interaction in a `bottom-up´ approach, bridging the gap from single atoms up to large droplets with bulk-like behavior. The special focus lies on indirect ionization processes mediated by the transfer of charge and excitation due to electron correlations. In pure He droplets, indirect ionization (autoionization) proceeds upon single excitation into high-lying levels, or upon multiple excitation which occurs for large droplets. In doped He droplets, indirect ionization of the dopant proceeds via charge or excitation transfer from the host to the dopant or vice versa in processes akin to Penning ionization or interatomic Coulombic decay (ICD). The comparison of He droplets with Ne clusters, both pure and doped, will elucidate fundamental aspects of photoionization of clusters associated with their quantum liquid respectively solid states. The employed method - coincidence velocity-map imaging detection of electrons and ions - gives detailed insight into the EUV-induced photodynamics by fragment mass-correlated measurement of the electron and ion energies and angular distributions. These studies will assess the potential of He droplets of serving as a medium for EUV photoelectron spectroscopy of embedded molecules and complexes and of serving as substrates for XUV diffraction imaging studies at free-electron lasers.

• DFG Programme: Research Grants
• International Connection: Denmark