@article{MedinaLagdsmandBenLtaiefetal.2023, author = {Medina, Cristian and L{\ae}gdsmand, Asbj{\o}rn {\O}rnemark and Ben Ltaief, Ltaief and Hoque, Ziaul and Roos, Andreas Hult and Jurkovičov{\´a}, Lucie and Hort, Ondřej and Finke, Ondřej and Albrecht, Martin and Nejdl, Jaroslav and Stienkemeier, Frank and Andreasson, Jakob and Klimešov{\´a}, Eva and Krikunova, Maria and Heidenreich, Andreas and Mudrich, Marcel}, title = {Long-lasting XUV activation of helium nanodroplets for avalanche ionization}, series = {New Journal of Physics}, volume = {25}, journal = {New Journal of Physics}, publisher = {Institute of Physics (IOP)}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-17701}, year = {2023}, abstract = {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 ignition of a nanoplasma at short delay times \${\sim}200\$ 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 appears 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.}, language = {en} }