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A: Fachverband Atomphysik

A 34: Poster VII

A 34.3: Poster

Donnerstag, 14. März 2024, 17:00–19:00, Tent B

multiply charged ions from highly-charged helium droplets — •shaimaa Habib — 1Universität Innsbruck, Institut für Ionenphysik und Angewandte Physik, Technikerstr. 25, A-6020 Innsbruck, Austria

Helium droplets have been demonstrated to pick up dopants from the gas phase, and evaporative cooling enables experiments at temperatures below 1 K [1]. Massive doping of neutral droplets leads to the formation of nanoparticles and quantum wires which were studied after deposition with high resolution microscopy [2] and in situ via coherent X-ray diffraction [3]. Recently, we discovered that large helium droplets can become highly-charged [4]. The charge centers self-organize as two-dimensional Wigner crystals at the surface of the droplets and act as seeds for the growth of dopant clusters [5]. Cluster ions and charged nanoparticles of a specific size and composition can be formed by this technique with unprecedented efficiency. Dopant cluster ions can be extracted by collision induced evaporation of the host droplet [6,7] or by splashing of the droplet upon surface impact [8]. Both methods are suitable to form high yields of He tagged ions of both polarities which enables messenger type spectroscopy of all kinds of cold ions. The location of charge centers in multiply charged He droplets close to the surface makes them accessible for subsequent interactions with metastable He atoms which leads to Penning ionization and the formation of cold multiply-charged dopant ions. For many dopant clusters, we obtain critical sizes of di- and trications that are well below the values obtained by conventional techniques.

Keywords: cluster ions; coherent X-ray diffraction; triply-charged charged cluster ions; helium droplets