Bonn 2025 – scientific programme
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MO: Fachverband Molekülphysik
MO 20: Poster – Molecular Spectroscopy and Dynamics
MO 20.2: Poster
Wednesday, March 12, 2025, 17:00–19:00, Tent
Towards laser spectroscopy of highly excited states of H3+ — •Marleen Maxton, Lukas Berger, Florian Grussie, Oldřich Novotný, Viviane C. Schmidt, Aigars Znotins, and Holger Kreckel — Max-Planck-Institut für Kernphysik, Heidelberg
The H3+ ion is the simplest polyatomic molecule. Apart from being an important benchmark for theoretical calculations, H3+ is one of the main drivers of astrochemistry in dilute interstellar clouds. Despite the structural simplicity of H3+, its spectrum at higher excitation remains largely unexplored, with the highest reported transition occuring at around 16 500 cm−1 with respect to the ground state, less than halfway from the dissociation energy of 35 000 cm−1. To extend the reach of laser spectroscopy beyond previous limits, a concept for a multi-color spectroscopy scheme was proposed [1]. In this approach, highly excited states are populated from the lowest ground states via long-lived metastable intermediates in a two-step laser excitation process, followed by UV photodissociation. For such studies, the Cryogenic Storage Ring (CSR) at the Max-Planck-Institut für Kernphysik provides an ideal platform, combining long storage times for intermediate state population with highly sensitive detection of the dissociation products in an almost background free cryogenic environment. A rotationally cold molecular ion beam is produced by a supersonic expansion source, stored in the CSR and probed for extended periods of time. Currently, the first excitation step is being implemented at the CSR, with plans to realize the full spectroscopy scheme in the future.
[1] Znotins et al., J. Mol. Spectrosc. 378, 111476 (2021)
Keywords: Triatomic hydrogen; Molecular ions; Laser spectroscopy; Storage ring