Helium nanodroplets provide a highly versatile and unique environment for trapping and cooling dopant species to ultralow temperatures. In particular, highly charged helium droplets open exciting new avenues for investigating fundamental physical and chemical processes. In recent studies, we are examining how charges are distributed within individual droplets and how these charges can act as nucleation sites for the formation of molecular and cluster ions, as well as larger nanoparticles, all within a single droplet.

In this talk, I will focus on the use of highly charged helium droplets for the efficient formation of helium-tagged molecular ions, which enables high-resolution electronic and vibrational spectroscopy of cold molecular ions [1]. This approach allows us to obtain precise absorption spectra of astrochemical relevant ions, with a particular emphasis on carbonaceous species such as linear and cyclic carbon chains, fullerenes, and polycyclic aromatic hydrocarbons [2–4].

By comparing our laboratory spectra with astronomical observations, we aim to identify new molecular ion species present in the interstellar medium [5]. Furthermore, I will discuss how the unique low-temperature environment of helium nanodroplets can be exploited to study chemical reactions under cryogenic conditions. To extend these studies to longer timescales, up to several seconds or even minutes, we have recently developed a novel setup for trapping charged helium droplets in an electrostatic ion trap. I will present first results from these experiments and provide an outlook on future directions in this research field.

[1] S. Bergmeister et al., Rev. Sci. Instrum. 94, 055105 (2023)
[2] L. Ganner et al., Phys. Rev. Lett. 133, 023001 (2024)
[3] L. Ganner et al., Astrophys. J. 993, 47 (2025)
[4] L. Ganner et al., ACS Earth Space Chem. (2025)
[5] S. A. Krasnokutski et al., Astrophys. J. 982, 34 (2025)

Elisabeth Gruber studied Technical Physics at TU Wien, where she completed her PhD in 2017. Following her doctoral studies, she conducted postdoctoral research at Aarhus University in Denmark. Since 2020, she has been researching and teaching at the Department of Ion Physics and Applied Physics at the University of Innsbruck. There, she established her own research group in cold molecular ion physics with support from an FWF Hertha-Firnberg Fellowship and an FWF Elise-Richter Grant. In 2025, she was awarded the FWF ASTRA Prize to further advance her research program.