Mainz 2026 – scientific programme
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MO: Fachverband Molekülphysik
MO 21: Poster – Cluster and Nanoparticles (joint session MO/A)
MO 21.1: Poster
Wednesday, March 4, 2026, 17:00–19:00, Philo 1. OG
Penning ionization and direct photoionization of Mg and Na doped in helium nanodroplets — •Rajni Rajni1, Narcis-Silviu Blaj1, Asbjorn Ornemark Lagdsmand1, Marcel Mudrich1, Ltaief L. Ben2, Niklas Scheel2, and Henrik Pedersen2 — 1Institute of Physics, University of Kassel, D-34132 Kassel, Germany — 2Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark
We investigate the direct photoionization and Penning ionization of alkali (Na) and alkaline-earth metals (Mg) embedded in superfluid helium nanodroplets under irradiation with extreme ultraviolet (XUV) synchrotron radiation that resonantly excites the He droplets. Helium is a well-suited system for studying indirect ionization processes due to the simple electronic structure of He, well-resolved electron spectra, weak interaction with embedded species, efficient pick up of molecules and controlled aggregation inside the nanodroplets. We measured spectra of all electrons and of electrons recorded in coincidence with specific ions for He nanodroplets doped with Mg and Na atoms. For Na, the Penning ionization electron spectrum is well resolved but shifted due to attractive interaction of the Na atom and the excited He* (short-range interatomic Coulombic decay). For Mg, we observe a pronounced enhancement of shake-up ionization where an excited Mg+ ion is produced in the Penning process. Shake-up states are only weakly present in direct photoelectron spectra.
Keywords: Penning ionization; Direct photoionization; Helium nanodroplets; Extreme ultraviolet (XUV) synchrotron radiation; Interatomic Coulombic decay