SAMOP 2023 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 6: Poster I
MO 6.14: Poster
Dienstag, 7. März 2023, 16:30–19:00, Empore Lichthof
Long-lasting XUV-induced ignition of avalanche ionization of helium nanodroplets — •C. Media1, A. Ø. Laegdsmand2, L. Ben Ltaief2, Z Hoque3, A. H. Roos3, M. Jurkovic3, O. Hort3, O. Finke3, M. Albrecht3, J. Nejdl3, F. Stienkemeier1, E. Klimesova3, M. Krikunova3, A. Heidenreich4, and M. Mudrich2 — 1Institute of Physics, University of Freiburg, Freiburg, Germany — 2Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark — 3ELI Beamlines Centre, FZU- Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, 182 21 Prague, Czechia — 4IKERBASQUE, Basque Foundation for Science, 48011 Bilbao, Spain
We study the dynamics of avalanche ionization of pure helium nanodroplets activated by a weak extreme-ultraviolet (XUV) pulse and driven by an intense near-infrared (NIR) pulse. In addition to a transient enhancement of the droplet ignition probability at short delay times $\sim200$~fs, long-term activation of the nanodroplets lasting up to a few nanoseconds is observed. Molecular dynamics simulations suggest that the short-term activation is caused by the injection of seed electrons into the droplets by XUV photoemission. Long-term activation is due to electrons remaining loosely bound to photoions which form stable `snowball' structures in the droplets. Thus, we show that XUV irradiation can induce long-lasting changes of the strong-field optical properties of nanoparticles, potentially opening new routes to controlling avalanche-ionization phenomena in nanostructures and condensed-phase systems.