SAMOP 2023 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 13: Poster II

MO 13.2: Poster

Mittwoch, 8. März 2023, 16:30–19:00, Empore Lichthof

Merged-beams experiments on molecular ion-neutral reactions for astrochemistry — •Pierre-Michel Hillenbrand¹, Xavier Urbain², and Daniel Wolf Savin³ — ¹Justus-Liebig Universität, Giessen, Germany — ²Université catholique de Louvain, Louvain-la-Neuve, Belgium — ³Columbia University, New York, USA

The gas-phase formation of complex molecules in the interstellar medium proceeds dominantly through barrierless ion-neutral reactions at typical temperatures of 10−100 K. Our merged-beams apparatus at Columbia University in New York City enables us to measure energy-dependent absolute cross sections of molecular formation processes for reactions of singly-charged molecules with neutral atoms and derive temperature-dependent thermal rate coefficients for individual product channels. Focusing on key reactions implemented in astrochemical models as well as on systems of fundamental interest, we have recently studied the reactions

D+H₃⁺→ H₂D⁺ + H [1],

D+H₂D⁺→ D₂H⁺ + H and D+D₂H⁺→ D₃⁺ + H [2],

C+H₂⁺→ CH⁺ + H and C+D₂⁺→ CD⁺ + D [3],

O+H₃⁺→ OH⁺ + H₂ and O+H₃⁺→ H₂O⁺ + H [4].
For example, the branching ratio for the two product channels of the O+H₃⁺ reaction is relevant for accurately modeling the gas-phase formation of water in the diffuse and dense molecular clouds.
[1] Astrophys. J. 877, 38 (2019). [2] J. Chem. Phys. 154, 084307 (2021). [3] Phys. Chem. Chem. Phys. 22, 27364 (2020). [4] Astrophys. J., 927, 47 (2022).