Mainz 2026 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 29: Cluster and Nanoparticles (joint session MO/A)

MO 29.3: Vortrag

Donnerstag, 5. März 2026, 16:00–16:15, P 105

Measuring the speed of interatomic Coulombic decay in helium nanodroplets — •Asbjørn Ørnemark Laegdsmand¹, Ltaief Ben Ltaief², Eva Klimesova³, Keshav Sishodia³, Martin Albrecht³, and Marcel Mudrich¹ — ¹Institute of Physics, University of Kassel, 34132 Kassel, Germany — ²Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark — ³ELI Beamlines, The Extreme Light Infrastructure ERIC, Za Radnicí 835, 252 41 Dolní Břežany, Czech Republic

Helium nanodroplets are an interesting *test tube* for many types of interatomic reactions. In this work we have looked at both interatomic Coulombic decay (ICD) and laser-assisted electron scattering (LAES). We have measured the rate of ICD in lithium-doped helium nanodroplets by an EUV-pump NIR-probe scheme.

The nanodroplets are resonantly excited into the 1s 2p ¹P state with a 21.6 eV pump pulse and multi-photon ionized with an 1.56 eV probe pulse. ICD and LAES electrons are detected with in a magnetic bottle electron spectrometer. Arrival of the probe pulse ionizes most of the 1s 2p ¹P He, quenching the ICD process. Thus by varying the time delay between pump and probe we measure the speed of the ICD for different droplet sizes.

From the resulting electron spectra we distinguish several ionization pathways, such as ICD, LAES and above threshold ionization. We model the dynamics of the different pathways by rate equations and estimate their contribution to the total electron yield as a function of pump-probe delay time.

Keywords: interatomic Coulombic decay; helium nanodroplet; pump–probe spectroscopy; high-harmonic generation