SAMOP 2023 – scientific programme
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A: Fachverband Atomphysik
A 25: Cluster and Experimental Techniques (joint session MO/A)
A 25.1: Talk
Thursday, March 9, 2023, 14:30–14:45, F142
Characterization of a simple supersonic expansion source for small molecular ions — •Lukas Berger1, Aigars Znotins1, Florian Grussie1, Damian Müll1, Felix Nuesslein1, Arnaud Dochain2, Joffrey Fréreux2, Xavier Urbain2, and Holger Kreckel1 — 1Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany — 2Institute of Condensed Matter and Nanosciences, Université Catholique de Louvain, Louvain-la-Neuve, B-1348 Belgium
The Cryogenic Storage Ring (CSR) [1] at the MPI for Nuclear Physics allows for the storage of molecular ions of almost arbitrary mass at extreme vacuum (residual gas densities on the order of 1000 cm-3) and at low temperature (T < 5K). In this environment, small infrared-active molecular ions will cool to their lowest rotational states within minutes. However, some astrophysically relevant molecular ions lack a permanent dipole moment (e.g.: H2+, H3+, H3 O+) and have to be produced in cold ion sources prior to injection, as they do not cool on experimentally accessible time scales.
Here we present the design of a simple supersonic expansion source based on a commercial pulsed valve and an electric discharge. It allows for the production of intense pulses of small molecular ions. We use high-resolution photodissociation spectroscopy of N2 O+, employing the STARGATE setup [2] at the Université Catholique de Louvain, to characterize the internal excitation of the molecular ions and extract their rotational temperature.
[1] Von Hahn et al., Rev. Sci. Instrum. 87, 063115 (2016)
[2] Bejjani et al., Rev. Sci. Instrum. 92, 033307 (2021)