Photoelectron and photoion imaging spectroscopy of metal-doped nanodroplets and rare gas clusters

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The goal of this project is to study the energetics and dynamics of excited states of single metal atoms attached to ultracold helium nanodroplets and to rare gas clusters. These conceptionally simple benchmark systems establish the link between gas-phase quantum dynamics and condensed-phase photophysics. Depending on the level of excitation of the solute atom, on the nature of the host cluster, and on the coupling strength between guest and host a rich spectrum of dynamical phenomena is initiated by laser excitation that proceed on different time scales. These processes include photo-induced desorption, partial or complete solvation, cluster-induced relaxation, complex formation, as well as the formation of unusual Rydberg states of the whole cluster.In a combined spectroscopic and time-resolved study we aim at disentangling various elementary processes, at determining their dynamics and kinematics, and at classifying the systems according to the degree of guest-host coupling and to the nature of their photophysical response. Specific dynamical effects induced by the quantum nature of the helium solvent will by identified. The velocity-map imaging (VMI) technique is applied to obtaining angle-resolved photoelectron and photoion spectra and combined with tunable narrowband nanosecond lasers and femtosecond lasers for pump-probe photoionization. Two-color resonant ionization will allow to perform ZEKE and MATI spectroscopy of excited states of metal atom-cluster complexes that are limited in resolution only by the bandwidth of the laser (~ 0.1 cm-1). These studies will have implications for the photodynamics and photochemistry of metals at surfaces and in condensed phase environments.