Refine
Document Type
- Article (1)
Year of publication
- 2023 (1)
Institute
Language
- English (1)
Has Fulltext
- yes (1)
Is part of the Bibliography
- yes (1)
Keywords
- avalanche ionization (1)
- extreme ultraviolet (1)
- helium nanodroplet (1)
- high-harmonic generation (1)
- nanoplasma (1)
- pump–probe spectroscopy (1)
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.