SAMOP 2023 – wissenschaftliches Programm

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SYHD: Symposium Molecules in Helium Droplets

SYHD 1: Molecules in Helium Droplets

SYHD 1.4: Hauptvortrag

Mittwoch, 8. März 2023, 12:30–13:00, E415

Messenger spectroscopy of molecular ions -- Development of a new experimental setup — •Elisabeth Gruber — Institute of Ion Physics and Applied Physics, Universität Innsbruck, A-6020 Innsbruck, Austria

Helium nanodroplets (HNDs) provide an inert matrix with outstanding properties to isolate diverse molecular ions, to grow complexes and clusters at sub-Kelvin temperature and to study the latter spectroscopically. Here, we present a newly developed experimental setup, which allows the formation of mass-selected and helium-tagged molecular ions, perfectly suitable for messenger-spectroscopy, by using HNDs instead of the commonly used RF-multipole trap technique. The setup combines an in-house-assembled helium nanocluster source with a commercially available quadrupole time-of-flight mass spectrometer. In the first step, HNDs are highly ionized by electron impact and afterwards doped with the molecules of interest. A gentle shrinking of the helium matrix of the doped HNDs by collisions with helium gas delivers helium-tagged molecular ions, detached from the helium droplets due to Coulomb repulsion. A subsequent quadrupole mass filter allows the selection of a specific dopant-helium-complex, which is then analysed spectroscopically. In contrast to previous studies, where the absorption spectra are predominantly obtained from the precursor ion depletion, the new setup enables the detection of the photoproduct from virtually zero background signal. This enables high quality spectra even for weak absorption lines at reduced data acquisition times. Recent results obtained with the new setup will be presented.