TY - JOUR A1 - Jurkovičová, Lucie A1 - Ben Ltaief, Ltaief A1 - Roos, Andreas Hult A1 - Hort, Ondřej A1 - Finke, Ondřej A1 - Albrecht, Martin A1 - Hoque, Ziaul A1 - Klimešová, Eva A1 - Sundaralingam, Akgash A1 - Antipenkov, Roman A1 - Grenfell, Annika A1 - Špaček, Alexandr A1 - Szuba, Wojciech A1 - Krikunova, Maria A1 - Mudrich, Marcel A1 - Nejdl, Jaroslav A1 - Andreasson, Jakob T1 - Bright continuously tunable vacuum ultraviolet source for ultrafast spectroscopy JF - Communications Physics N2 - Ultrafast electron dynamics drive phenomena such as photochemical reactions, catalysis, and light harvesting. To capture such dynamics in real-time, femtosecond to attosecond light sources are extensively used. However, an exact match between the excitation photon energy and a characteristic resonance is crucial. High-harmonic generation sources are advantageous in terms of pulse duration but limited in spectral tunability in the vacuum ultraviolet range. Here, we present a monochromatic femtosecond source continuously tunable around 21eV photon energy utilizing the second harmonic of an optical parametric chirped pulse amplification laser system to drive high-harmonic generation. The unique tunability of the source is verified in an experiment probing the interatomic Coulombic decay in doped He nanodroplets across the He absorption bands. Moreover, we achieved intensities sufficient for driving collective processes in multiply excited helium nanodroplets, which have been previously observed only at free electron lasers. Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-18462 SN - 2399-3650 VL - 7 PB - Nature Publishing Group ER -